Spatiotemporal expression of Ezh2 in the developing mouse cochlear sensory epithelium.

PubMed

Chen, Yan; Li, Wenyan; Li, Wen; Chai, Renjie; Li, Huawei

2016-09-01

The enhancer of zeste 2 polycomb repressive complex 2 subunit (Ezh2) is a histone-lysine Nmethyltransferase enzyme that participates in DNA methylation. Ezh2 has also been reported to play crucial roles in stem cell proliferation and differentiation. However, the detailed expression profile of Ezh2 during mouse cochlear development has not been investigated. Here, we examined the spatiotemporal expression of Ezh2 in the cochlea during embryonic and postnatal development. Ezh2 expression began to be observed in the whole otocyst nuclei at embryonic day 9.5 (E9.5). At E12.5, Ezh2 was expressed in the nuclei of the cochlear prosensory epithelium. At E13.5 and E15.5, Ezh2 was expressed from the apical to the basal turns in the nuclei of the differentiating cochlear epithelium. At postnatal day (P) 0 and 7, the Ezh2 expression was located in the nuclei of the cochlear epithelium in all three turns and could be clearly seen in outer and inner hair cells, supporting cells, the stria vascularis, and spiral ganglion cells. Ezh2 continued to be expressed in the cochlear epithelium of adult mice. Our results provide the basic Ezh2 expression pattern and might be useful for further investigating the detailed role of Ezh2 during cochlear development.

Predicting the location of missing outer hair cells using the electrical signal recorded at the round window

PubMed Central

Chertoff, Mark E.; Earl, Brian R.; Diaz, Francisco J.; Sorensen, Janna L.; Thomas, Megan L. A.; Kamerer, Aryn M.; Peppi, Marcello

2014-01-01

The electrical signal recorded at the round window was used to estimate the location of missing outer hair cells. The cochlear response was recorded to a low frequency tone embedded in high-pass filtered noise conditions. Cochlear damage was created by either overexposure to frequency-specific tones or laser light. In animals with continuous damage along the partition, the amplitude of the cochlear response increased as the high-pass cutoff frequency increased, eventually reaching a plateau. The cochlear distance at the onset of the plateau correlated with the anatomical onset of outer hair cell loss. A mathematical model replicated the physiologic data but was limited to cases with continuous hair cell loss in the middle and basal turns. The neural contribution to the cochlear response was determined by recording the response before and after application of Ouabain. Application of Ouabain eliminated or reduced auditory neural activity from approximately two turns of the cochlea. The amplitude of the cochlear response was reduced for moderate signal levels with a limited effect at higher levels, indicating that the cochlear response was dominated by outer hair cell currents at high signal levels and neural potentials at low to moderate signal levels. PMID:25190395

Topography of neurovascular structures in relation to round window and how it relates to cochlear implantation.

PubMed

Singla, Anjali; Gupta, Tulika; Sahni, Daisy; Gupta, Ashok Kumar; Aggarwal, Anjali

2017-12-01

The purpose of this investigation was to evaluate the distances and angles on basal turn of cochlea in relation to round window at which the jugular bulb, internal carotid artery and facial nerve are at maximal risk and their implications in cochlear implantation (CI). Fifty-four cadaveric temporal bones were microdissected to expose the basal turn of cochlea, the carotid canal, the facial canal and the jugular fossa. The points were marked on the basal turn of cochlea, where there was minimum distance of basal turn of cochlea from the roof of the jugular fossa (point a), carotid canal (point b) and facial canal (point c). The distances and angles of these points from the round window were measured. The points a, b and c were at mean (range) distances of 2.8 mm (1.3-4.1 mm), 8.4 mm (6.5-10.4 mm) and 16.4 mm (12.5-20.5 mm) and at mean angles of 30° (15°-45°), 111° (71°-136°) and 284° (255°-315°), respectively, from the round window. This study highlights that 2.8 ± 0.5 mm (30 ± 5.40), 8.4 ± 1 mm (111 ± 12.70) and 16.4 ± 1.7 mm (284 ± 13.5) from the round window are the high-risk points on the basal turn of the cochlea for the jugular bulb, internal carotid artery and facial nerve, respectively. A wide range found for each parameter indicates that it is mandatory to evaluate these distances in each CI patient on preoperative radiographs to avoid intraoperative injury to these vital structures.

Application of Curved MPR Algorithm to High Resolution 3 Dimensional T2 Weighted CISS Images for Virtual Uncoiling of Membranous Cochlea as an Aid for Cochlear Morphometry.

PubMed

Kumar, Joish Upendra; Kavitha, Y

2017-02-01

With the use of various surgical techniques, types of implants, the preoperative assessment of cochlear dimensions is becoming increasingly relevant prior to cochlear implantation. High resolution CISS protocol MRI gives a better assessment of membranous cochlea, cochlear nerve, and membranous labyrinth. Curved Multiplanar Reconstruction (MPR) algorithm provides better images that can be used for measuring dimensions of membranous cochlea. To ascertain the value of curved multiplanar reconstruction algorithm in high resolution 3-Dimensional T2 Weighted Gradient Echo Constructive Interference Steady State (3D T2W GRE CISS) imaging for accurate morphometry of membranous cochlea. Fourteen children underwent MRI for inner ear assessment. High resolution 3D T2W GRE CISS sequence was used to obtain images of cochlea. Curved MPR reconstruction algorithm was used to virtually uncoil the membranous cochlea on the volume images and cochlear measurements were done. Virtually uncoiled images of membranous cochlea of appropriate resolution were obtained from the volume data obtained from the high resolution 3D T2W GRE CISS images, after using curved MPR reconstruction algorithm mean membranous cochlear length in the children was 27.52 mm. Maximum apical turn diameter of membranous cochlea was 1.13 mm, mid turn diameter was 1.38 mm, basal turn diameter was 1.81 mm. Curved MPR reconstruction algorithm applied to CISS protocol images facilitates in getting appropriate quality images of membranous cochlea for accurate measurements.

[Cochlear implantation through the middle fossa approach].

PubMed

Szyfter, W; Colletti, V; Pruszewicz, A; Kopeć, T; Szymiec, E; Kawczyński, M; Karlik, M

2001-01-01

The inner part of cochlear implant is inserted into inner ear during surgery through mastoid and middle ear. It is a classical method, used in the majority cochlear centers in the world. This is not a suitable method in case of chronic otitis media and middle ear malformation. In these cases Colletti proposed the middle fossa approach and cochlear implant insertion omitting middle ear structures. In patient with bilateral chronic otitis media underwent a few ears operations without obtaining dry postoperative cavity. Cochlear implantation through the middle fossa approach was performed in this patient. The bone fenster was cut, temporal lobe was bent and petrosus pyramid upper surface was exposed. When the superficial petrosal greater nerve, facial nerve and arcuate eminence were localised, the cochlear was open in the basal turn and electrode were inserted. The patient achieves good results in the postoperative speech rehabilitation. It confirmed Colletti tesis that deeper electrode insertion in the cochlear implantation through the middle fossa approach enable use of low and middle frequencies, which are very important in speech understanding.

Cochlear implants and ex vivo BDNF gene therapy protect spiral ganglion neurons.

PubMed

Rejali, Darius; Lee, Valerie A; Abrashkin, Karen A; Humayun, Nousheen; Swiderski, Donald L; Raphael, Yehoash

2007-06-01

Spiral ganglion neurons often degenerate in the deaf ear, compromising the function of cochlear implants. Cochlear implant function can be improved by good preservation of the spiral ganglion neurons, which are the target of electrical stimulation by the implant. Brain derived neurotrophic factor (BDNF) has previously been shown to enhance spiral ganglion survival in experimentally deafened ears. Providing enhanced levels of BDNF in human ears may be accomplished by one of several different methods. The goal of these experiments was to test a modified design of the cochlear implant electrode that includes a coating of fibroblast cells transduced by a viral vector with a BDNF gene insert. To accomplish this type of ex vivo gene transfer, we transduced guinea pig fibroblasts with an adenovirus with a BDNF gene cassette insert, and determined that these cells secreted BDNF. We then attached BDNF-secreting cells to the cochlear implant electrode via an agarose gel, and implanted the electrode in the scala tympani. We determined that the BDNF expressing electrodes were able to preserve significantly more spiral ganglion neurons in the basal turns of the cochlea after 48 days of implantation when compared to control electrodes. This protective effect decreased in the higher cochlear turns. The data demonstrate the feasibility of combining cochlear implant therapy with ex vivo gene transfer for enhancing spiral ganglion neuron survival.

Cadaveric feasibility study of da Vinci Si-assisted cochlear implant with augmented visual navigation for otologic surgery.

PubMed

Liu, Wen P; Azizian, Mahdi; Sorger, Jonathan; Taylor, Russell H; Reilly, Brian K; Cleary, Kevin; Preciado, Diego

2014-03-01

To our knowledge, this is the first reported cadaveric feasibility study of a master-slave-assisted cochlear implant procedure in the otolaryngology-head and neck surgery field using the da Vinci Si system (da Vinci Surgical System; Intuitive Surgical, Inc). We describe the surgical workflow adaptations using a minimally invasive system and image guidance integrating intraoperative cone beam computed tomography through augmented reality. To test the feasibility of da Vinci Si-assisted cochlear implant surgery with augmented reality, with visualization of critical structures and facilitation with precise cochleostomy for electrode insertion. Cadaveric case study of bilateral cochlear implant approaches conducted at Intuitive Surgical Inc, Sunnyvale, California. Bilateral cadaveric mastoidectomies, posterior tympanostomies, and cochleostomies were performed using the da Vinci Si system on a single adult human donor cadaveric specimen. Radiographic confirmation of successful cochleostomies, placement of a phantom cochlear implant wire, and visual confirmation of critical anatomic structures (facial nerve, cochlea, and round window) in augmented stereoendoscopy. With a surgical mean time of 160 minutes per side, complete bilateral cochlear implant procedures were successfully performed with no violation of critical structures, notably the facial nerve, chorda tympani, sigmoid sinus, dura, or ossicles. Augmented reality image overlay of the facial nerve, round window position, and basal turn of the cochlea was precise. Postoperative cone beam computed tomography scans confirmed successful placement of the phantom implant electrode array into the basal turn of the cochlea. To our knowledge, this is the first study in the otolaryngology-head and neck surgery literature examining the use of master-slave-assisted cochleostomy with augmented reality for cochlear implants using the da Vinci Si system. The described system for cochleostomy has the potential to improve the surgeon's confidence, as well as surgical safety, efficiency, and precision by filtering tremor. The integration of augmented reality may be valuable for surgeons dealing with complex cases of congenital anatomic abnormality, for revision cochlear implant with distorted anatomy and poorly pneumatized mastoids, and as a method of interactive teaching. Further research into the cost-benefit ratio of da Vinci Si-assisted otologic surgery, as well as refinements of the proposed workflow, are required before considering clinical studies.

Fabrication and evaluation of an improved polymer-based cochlear electrode array for atraumatic insertion.

PubMed

Gwon, Tae Mok; Min, Kyou Sik; Kim, Jin Ho; Oh, Seung Ha; Lee, Ho Sun; Park, Min-Hyun; Kim, Sung June

2015-04-01

An atraumatic cochlear electrode array has become indispensable to high-performance cochlear implants such as electric acoustic stimulation (EAS), wherein the preservation of residual hearing is significant. For an atraumatic implantation, we propose and demonstrate a new improved design of a cochlear electrode array based on liquid crystal polymer (LCP), which can be fabricated by precise batch processes and a thermal lamination process, in contrast to conventional wire-based cochlear electrode arrays. Using a thin-film process of LCP-film-mounted silicon wafer and thermal press lamination, we devise a multi-layered structure with variable layers of LCP films to achieve a sufficient degree of basal rigidity and a flexible tip. A peripheral blind via and self-aligned silicone elastomer molding process can reduce the width of the array. Measuring the insertion and extraction forces in a human scala tympani model, we investigate five human temporal bone insertion trials and record electrically evoked auditory brainstem responses (EABR) acutely in a guinea pig model. The diameters of the finalized electrode arrays are 0.3 mm (tip) and 0.75 mm (base). The insertion force with a displacement of 8 mm from a round window and the maximum extraction force are 2.4 mN and 34.0 mN, respectively. The electrode arrays can be inserted from 360° to 630° without trauma at the basal turn. The EABR data confirm the efficacy of the array. A new design of LCP-based cochlear electrode array for atraumatic implantation is fabricated. Verification indicates that foretells the development of an atraumatic cochlear electrode array and clinical implant.

Cochlear pathology following reimplantation of a multichannel scala tympani electrode array in the macaque.

PubMed

Shepherd, R K; Clark, G M; Xu, S A; Pyman, B C

1995-03-01

The histopathologic consequence of removing and reimplanting intracochlear electrode arrays on residual auditory nerve fibers is an important issue when evaluating the safety of cochlear prostheses. The authors have examined this issue by implanting multichannel intracochlear electrodes in macaque monkeys. Macaques were selected because of the similarity of the surgical technique used to insert electrodes into the cochlea compared to that in humans, in particular the ability to insert the arrays into the upper basal turn. Five macaques were bilaterally implanted with the Melbourne/Cochlear banded electrode array. Following a minimum implant period of 5 months, the electrode array on one side of each animal was removed and another immediately implanted. The animals were sacrificed a minimum of 5 months following the reinsertion procedure, and the cochleas prepared for histopathologic analysis. Long-term implantation of the electrode resulted in a relatively mild tissue response within the cochlea. Results also showed that inner and outer hair cell survival, although significantly reduced adjacent to the array, was normal in 8 of the 10 cochleas apicalward. Moreover, the electrode reinsertion procedure did not appear to adversely affect this apical hair cell population. Significant new bone formation was frequently observed in both control and reimplanted cochleas close to the electrode fenestration site and was associated with trauma to the endosteum and/or the introduction of bone chips into the cochlea at the time of surgery. Electrode insertion trauma, involving the osseous spiral lamina or basilar membrane, was more commonly observed in reimplanted cochleas. This damage was usually restricted to the lower basal turn and resulted in a more extensive ganglion cell loss. Finally, in a number of cochleas part of the electrode array was located within the scala media or scala vestibuli. These electrodes did not appear to evoke a more extensive tissue response or result in more extensive neural degeneration compared with electrodes located within the scala tympani. In conclusion, the present study has shown that the reimplantation of a multichannel scala, tympani electrode array can be achieved with minimal damage to the majority of cochlear structures. Increased insertion trauma, resulting in new bone formation and spiral ganglion cell loss, can occur in the lower basal turn in cases where the electrode entry point is difficult to identify due to proliferation of granulation and fibrous tissue.

Intracochlear Position of Cochlear Implants Determined Using CT Scanning versus Fitting Levels: Higher Threshold Levels at Basal Turn.

PubMed

van der Beek, Feddo B; Briaire, Jeroen J; van der Marel, Kim S; Verbist, Berit M; Frijns, Johan H M

2016-01-01

In this study, the effects of the intracochlear position of cochlear implants on the clinical fitting levels were analyzed. A total of 130 adult subjects who used a CII/HiRes 90K cochlear implant with a HiFocus 1/1J electrode were included in the study. The insertion angle and the distance to the modiolus of each electrode contact were determined using high-resolution CT scanning. The threshold levels (T-levels) and maximum comfort levels (M-levels) at 1 year of follow-up were determined. The degree of speech perception of the subjects was evaluated during routine clinical follow-up. The depths of insertion of all the electrode contacts were determined. The distance to the modiolus was significantly smaller at the basal and apical cochlear parts compared with that at the middle of the cochlea (p < 0.05). The T-levels increased toward the basal end of the cochlea (3.4 dB). Additionally, the M-levels, which were fitted in our clinic using a standard profile, also increased toward the basal end, although with a lower amplitude (1.3 dB). Accordingly, the dynamic range decreased toward the basal end (2.1 dB). No correlation was found between the distance to the modiolus and the T-level or the M-level. Furthermore, the correlation between the insertion depth and stimulation levels was not affected by the duration of deafness, age at implantation or the time since implantation. Additionally, the T-levels showed a significant correlation with the speech perception scores (p < 0.05). The stimulation levels of the cochlear implants were affected by the intracochlear position of the electrode contacts, which were determined using postoperative CT scanning. Interestingly, these levels depended on the insertion depth, whereas the distance to the modiolus did not affect the stimulation levels. The T-levels increased toward the basal end of the cochlea. The level profiles were independent of the overall stimulation levels and were not affected by the biographical data of the patients, such as the duration of deafness, age at implantation or time since implantation. Further research is required to elucidate how fitting using level profiles with an increase toward the basal end of the cochlea benefits speech perception. Future investigations may elucidate an explanation for the effects of the intracochlear electrode position on the stimulation levels and might facilitate future improvements in electrode design. © 2016 S. Karger AG, Basel.

Generalized arteriosclerosis and changes of the cochlea in young adults.

PubMed

Nomiya, Rie; Nomiya, Shigenobu; Kariya, Shin; Okano, Mitsuhiro; Morita, Norimasa; Cureoglu, Sebahattin; Schachern, Patricia A; Nishizaki, Kazunori; Paparella, Michael M

2008-12-01

To disclose the histopathologic findings of the cochlea in young adults with generalized arteriosclerosis. It is well known that arteriosclerosis begins and progresses during childhood. Although the relationship between arteriosclerosis and auditory function in elderly people was examined in many reports, the histopathologic effect of arteriosclerosis on the cochlea in young adults has not been studied. This study involved quantitative analysis, including the number of spiral ganglion cells, the loss of cochlear outer hair cells, and the areas of stria vascularis and spiral ligament. It included 10 temporal bones from 6 subjects with generalized arteriosclerosis and 10 age-matched normal control temporal bones from 7 subjects. The mean number of spiral ganglion cells in the cochlea with generalized arteriosclerosis was significantly lower than that in normal controls in the basal turn. The mean loss of outer hair cells in the cochlea with generalized arteriosclerosis was significantly greater than that of normal controls in the basal and apical turns. The stria vascularis and spiral ligament were severely atrophic, with generalized arteriosclerosis in the basal turn. There was no significant difference in the thickness of the spiral modiolar artery between generalized arteriosclerosis and normal controls. Degeneration of the cochlea, especially in the basal turn, was already apparent in young adults with generalized arteriosclerosis.

In vivo observation of dynamic perilymph formation using 4.7 T MRI with gadolinium as a tracer.

PubMed

Zou, Jing; Pyykkö, Ilmari; Counter, S Allen; Klason, Tomas; Bretlau, Poul; Bjelke, Börje

2003-10-01

To investigate the pharmacokinetics of gadolinium in the perilymphatic fluid spaces of the cochlea in vivo using high-resolution MRI to obtain information concerning perilymph formation. A Bruker Biospec Avance 47/40 experimental MRI system with a magnetic field strength of 4.7 T was used. Anesthetized pigmented guinea pigs were injected with the contrast agent Gd-diethylenetriaminepentaacetic acid-bismethylamide and placed in the magnet. The signal intensity of Gd in the tissues was used as a biomarker for dynamic changes in the perilymphatic fluid. The most rapid uptake of Gd in the perilymphatic fluid spaces occurred in the lower part of the modiolus, followed by the second turn of the scala tympani. Within the scala tympani, the distribution of Gd in the basal turn was significantly lower than that in the other turns. Destruction of the cochlear aqueduct was followed by an increase in Gd uptake in the perilymph instead of a reduction. These findings offer further evidence that the pervasive perilymphatic fluid derives from the cochlear blood supply via the cochlear glomeruli, which are in close proximity to the scala tympani within the modiolus, and the capillary in the spiral ligament. Cerebrospinal fluid communicates with perilymph via the cochlear aqueduct but is not the main source of perilymph. These findings are of relevance to the treatment of inner ear diseases, as well as to our understanding of the flow and source of perilymphatic fluid.

Stria vascularis and cochlear hair cell changes in syphilis: A human temporal bone study.

PubMed

Hızlı, Ömer; Kaya, Serdar; Hızlı, Pelin; Paparella, Michael M; Cureoglu, Sebahattin

2016-12-01

To observe any changes in stria vascularis and cochlear hair cells in patients with syphilis. We examined 13 human temporal bone samples from 8 patients with syphilis (our syphilis group), as well as 12 histopathologically normal samples from 9 age-matched patients without syphilis (our control group). We compared, between the two groups, the mean area of the stria vascularis (measured with conventional light microscopy connected to a personal computer) and the mean percentage of cochlear hair cell loss (obtained from cytocochleograms). In our syphilis group, only 1 (7.7%) of the 13 samples had precipitate in the endolymphatic or perilymphatic spaces; 8 (61.5%) of the samples revealed the presence of endolymphatic hydrops (4 cochlear, 4 saccular). The mean area of the stria vascularis did not significantly differ, in any turn of the cochlea, between the 2 groups (P>0.1). However, we did find significant differences between the 2 groups in the mean percentage of outer hair cells in the apical turn (P<0.026) and in the mean percentage of inner hair cells in the basal (P=0.001), middle (P=0.004), and apical (P=0.018) turns. In 7 samples in our syphilis group, we observed either complete loss of the organ of Corti or a flattened organ of Corti without any cells in addition to the absence of both outer and inner hair cells. In this study, syphilis led either to complete loss of the organ of Corti or to significant loss of cochlear hair cells, in addition to cochleosaccular hydrops. But the area of the stria vascularis did not change. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Stria Vascularis and Cochlear Hair Cell Changes in Syphilis: A Human Temporal Bone Study

PubMed Central

Hızlı, Ömer; Kaya, Serdar; Hızlı, Pelin; Paparella, Michael M.; Cureoglu, Sebahattin

2016-01-01

Objective To observe any changes in stria vascularis and cochlear hair cells in patients with syphilis Materials and Methods We examined 13 human temporal bone samples from 8 patients with syphilis (our syphilis group), as well as 12 histopathologically normal samples from 9 age-matched patients without syphilis (our control group). We compared, between the 2 groups, the mean area of the stria vascularis (measured with conventional light microscopy connected to a personal computer) and the mean percentage of cochlear hair cell loss (obtained from cytocochleograms). Results In our syphilis group, only 1 (7.7%) of the 13 samples had precipitate in the endolymphatic or perilymphatic spaces; 8 (61.5%) of the samples revealed the presence of endolymphatic hydrops (4 cochlear, 4 saccular). The mean area of the stria vascularis area did not significantly differ, in any turn of the cochlea, between the 2 groups (P > 0.1). However, we did find significant differences between the 2 groups in the mean percentage of outer hair cells in the apical turn (P < 0.026) and in the mean percentage of inner hair cells in the basal (P = 0.001), middle (P = 0.004), and apical (P = 0.018) turns. In 7 samples in our syphilis group, we observed either complete loss of the organ of Corti or a flattened organ of Corti without any cells in addition to the absence of both outer and inner hair cells. Conclusion In this study, syphilis led either to complete loss of the organ of Corti or to significant loss of cochlear hair cells, in addition to cochleosaccular hydrops. But the area of the stria vascularis did not change. PMID:26860231

3D optical coherence tomography image registration for guiding cochlear implant insertion

NASA Astrophysics Data System (ADS)

Cheon, Gyeong-Woo; Jeong, Hyun-Woo; Chalasani, Preetham; Chien, Wade W.; Iordachita, Iulian; Taylor, Russell; Niparko, John; Kang, Jin U.

2014-03-01

In cochlear implant surgery, an electrode array is inserted into the cochlear canal to restore hearing to a person who is profoundly deaf or significantly hearing impaired. One critical part of the procedure is the insertion of the electrode array, which looks like a thin wire, into the cochlear canal. Although X-ray or computed tomography (CT) could be used as a reference to evaluate the pathway of the whole electrode array, there is no way to depict the intra-cochlear canal and basal turn intra-operatively to help guide insertion of the electrode array. Optical coherent tomography (OCT) is a highly effective way of visualizing internal structures of cochlea. Swept source OCT (SSOCT) having center wavelength of 1.3 micron and 2D Galvonometer mirrors was used to achieve 7-mm depth 3-D imaging. Graphics processing unit (GPU), OpenGL, C++ and C# were integrated for real-time volumetric rendering simultaneously. The 3D volume images taken by the OCT system were assembled and registered which could be used to guide a cochlear implant. We performed a feasibility study using both dry and wet temporal bones and the result is presented.

The Pattern and Degree of Capsular Fibrous Sheaths Surrounding Cochlear Electrode Arrays

PubMed Central

Ishai, Reuven; Herrmann, Barbara S.; Nadol, Joseph B.; Quesnel, Alicia M.

2017-01-01

An inflammatory tissue reaction around the electrode array of a cochlear implant (CI) is common, in particular at the electrode insertion region (cochleostomy) where mechanical trauma often occurs. However, the factors determining the amount and causes of fibrous reaction surrounding the stimulating electrode, especially medially near the perimodiolar location, are unclear. Temporal bone (TB) specimens from patients who had undergone cochlear implantation during life with either Advanced Bionics (AB) Clarion TM or HiRes90KTM (Sylmar, CA, USA) or Cochlear TM Nucleus (Sydney, Australia) devices were evaluated. The thickness of the fibrous tissue surrounding the electrode array of both types of CI devices at both the lower (LB) and upper (UB) basal turns of the cochlea was quantified at three locations: the medial, inferior, and superior aspects of the sheath. Fracture of the osseous spiral lamina and/or marked displacement of the basilar membrane were interpreted as evidence of intracochlear trauma. In addition, post-operative word recognition scores, duration of implantation, and post-operative programming data were evaluated. Seven TBs from six patients implanted with AB devices and five TBs from five patients implanted with Nucleus devices were included. A fibrous capsule around the stimulating electrode array was present in all twelve specimens. TBs implanted with AB device had a significantly thicker fibrous capsule at the medial aspect than at the inferior or superior aspects at both locations (LB and UB) of the cochlea (Wilcoxon signed-ranks test, p<0.01). TBs implanted with a Nucleus device had no difference in the thickness of the fibrous capsule surrounding the track of the electrode array (Wilcoxon signed-ranks test, p>0.05). Nine of fourteen (64%) basal turns of the cochlea (LB and UB of seven TBs) implanted with AB devices demonstrated intracochlear trauma compared to two of ten (20%) basal turns of the cochlea (LB and UB of five TBs) with Nucleus devices, (Fisher exact test, p<0.05). There was no significant correlation between the thickness of the fibrous tissue and the duration of implantation or the word recognition scores (Spearman rho, p=0.06, p=0.4 respectively). Our outcomes demonstrated the development of a robust fibrous tissue sheath medially closest to the site of electric stimulation in cases implanted with the AB device electrode, but not in cases implanted with the Nucleus device. The cause of the asymmetric fibrous sheath may be multifactorial including insertional trauma, a foreign body response, and/or asymmetric current flow. PMID:28216124

Characterization of neuronal cell death in the spiral ganglia of a mouse model of endolymphatic hydrops.

PubMed

Semaan, Maroun T; Zheng, Qing Y; Han, Fengchan; Zheng, Yuxi; Yu, Heping; Heaphy, John C; Megerian, Cliff A

2013-04-01

Spiral ganglion neurons (SGN) in the Phex male mouse, a murine model of postnatal endolymphatic hydrops (ELH) undergo progressive deterioration reminiscent of human and other animal models of ELH with features suggesting apoptosis as an important mechanism. Histologic analysis of the mutant's cochlea demonstrates ELH by postnatal Day (P) 21 and SGN loss by P90. The SGN loss seems to occur in a consistent topographic pattern beginning at the cochlear apex. SGN were counted at P60, P90, and P120. Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), quantitative PCR, and immunohistochemical analyses of activated caspase-3, caspase-8, and caspase-9 were performed on cochlear sections obtained from mutants and controls. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling assay (TUNEL) was carried out on 2 mutants and 2 controls. Corrected SGN counts in control mice were greater in the apical turn of the cochleae at P90 and P120, respectively (p < 0.01). Increased expression of activated caspase-3, caspase-8, and caspase-9 was seen in the mutant. At later time points, activated caspase expression gradually declined in the apical turns and increased in basal turns of the cochlea. Quantitative and semiquantitative PCR analysis confirmed increased expression of caspase-3, caspase-8, and caspase-9 at P21 and P40. TUNEL staining demonstrated apoptosis at P90 in the apical and basal turns of the mutant cochleae. SGN degeneration in the Phex /Y mouse seems to mimic patterns observed in other animals with ELH. Apoptosis plays an important role in the degeneration of the SGN in the Phex male mouse.

Effects of perilymphatic pressure, sodium nitroprusside, and bupivacaine on cochlear fluid pH of guinea pigs.

PubMed

Suzuki, Masaaki; Kotani, Ryosuke

2015-01-01

Hydrostatic positive pressure and vasoconstrictor acidified the cochlear fluids, whereas the vasodilator made the fluids alkaline. CBF might play a role in regulating cochlea fluid pH. Cochlea fluid pH is highly dependent on the HCO3(-)/CO2 buffer system. Cochlear blood flow (CBF) supplies O2 and removes CO2. It is speculated that cochlear blood flow changes might affect the balance of the HCO3(-)/CO2 buffer system in the cochlea. It is known that the elevation of inner ear pressure decreases the CBF, and local application of vasodilating or vasoconstricting agents directly to the cochlea changes the CBF. The purpose of this study was to elucidate the effect of positive hydrostatic inner ear pressure and application of a vasodilator and vasoconstrictor of cochlear vessels on the pH of the endolymph and perilymph. The authors performed animal physiological experiments on 30 guinea pigs. Hydrostatic positive pressure was infused through a glass capillary tube inserted into the scala tympani of the basal turn. The vasodilator, nitric oxide donor (sodium nitroprusside; SNP), and the vasoconstrictor, bupivacaine, were placed topically onto the round window of the guinea pig cochlea. Endolymph pH (pHe) and endocochlear potential (EP) were monitored by double-barreled ion-selective microelectrodes in the second turn of the guinea pig cochlea. During the topical application study, scala vestibuli perilymph pH (pHv) was also measured simultaneously in the second turn. The application of hydrostatic positive pressure caused a decrease in pHe and EP. Positive perilymphatic pressure caused the endolymph to become acidic pressure-dependently. Application of 3.0% SNP evoked an increase in both the pHe and pHv, following by a gradual recovery to baseline levels. On the other hand, 0.5% bupivacaine caused a decrease in both the pHe and pHv. The EP during topical application showed slight, non-significant changes.

The pattern and degree of capsular fibrous sheaths surrounding cochlear electrode arrays.

PubMed

Ishai, Reuven; Herrmann, Barbara S; Nadol, Joseph B; Quesnel, Alicia M

2017-05-01

An inflammatory tissue reaction around the electrode array of a cochlear implant (CI) is common, in particular at the electrode insertion region (cochleostomy) where mechanical trauma often occurs. However, the factors determining the amount and causes of fibrous reaction surrounding the stimulating electrode, especially medially near the perimodiolar location, are unclear. Temporal bone (TB) specimens from patients who had undergone cochlear implantation during life with either Advanced Bionics (AB) Clarion ™ or HiRes90K™ (Sylmar, CA, USA) devices that have a half-band and a pre-curved electrode, or Cochlear ™ Nucleus (Sydney, Australia) device that have a full-band and a straight electrode were evaluated. The thickness of the fibrous tissue surrounding the electrode array of both types of CI devices at both the lower (LB) and upper (UB) basal turns of the cochlea was quantified at three locations: the medial, inferior, and superior aspects of the sheath. Fracture of the osseous spiral lamina and/or marked displacement of the basilar membrane were interpreted as evidence of intracochlear trauma. In addition, post-operative word recognition scores, duration of implantation, and post-operative programming data were evaluated. Seven TBs from six patients implanted with AB devices and five TBs from five patients implanted with Nucleus devices were included. A fibrous capsule around the stimulating electrode array was present in all twelve specimens. TBs implanted with AB device had a significantly thicker fibrous capsule at the medial aspect than at the inferior or superior aspects at both locations (LB and UB) of the cochlea (Wilcoxon signed-ranks test, p < 0.01). TBs implanted with a Nucleus device had no difference in the thickness of the fibrous capsule surrounding the track of the electrode array (Wilcoxon signed-ranks test, p > 0.05). Nine of fourteen (64%) basal turns of the cochlea (LB and UB of seven TBs) implanted with AB devices demonstrated intracochlear trauma compared to two of ten (20%) basal turns of the cochlea (LB and UB of five TBs) with Nucleus devices, (Fisher exact test, p < 0.05). There was no significant correlation between the thickness of the fibrous tissue and the duration of implantation or the word recognition scores (Spearman rho, p = 0.06, p = 0.4 respectively). Our outcomes demonstrated the development of a robust fibrous tissue sheath medially closest to the site of electric stimulation in cases implanted with the AB device electrode, but not in cases implanted with the Nucleus device. The cause of the asymmetric fibrous sheath may be multifactorial including insertional trauma, a foreign body response, and/or asymmetric current flow. Copyright © 2017 Elsevier B.V. All rights reserved.

Acoustic schwannoma with intracochlear extension and primary intracochlear schwannoma: removal through translabyrinthine approach with facial bridge cochleostomy and transcanal approach.

PubMed

Mazzoni, A; Zanoletti, E; Faccioli, C; Martini, A

2017-05-01

Intracochlear schwannomas can occur either as an extension of a larger tumor from the internal auditory canal, or as a solitary labyrinthine tumor. They are currently removed via a translabyrinthine approach extended to the basal turn, adding a transotic approach for tumors lying beyond the basal turn. Facial bridge cochleostomy may be associated with the translabyrinthine approach to enable the whole cochlea to be approached without sacrificing the external auditory canal and tympanum. We describe seven cases, five of which underwent cochlear schwannoma resection with facial bridge cochleostomy, one case with the same procedure for a suspect tumor and one, previously subjected to radical tympanomastoidectomy, who underwent schwannoma resection via a transotic approach. Facial bridge cochleostomy involved removing the bone between the labyrinthine and tympanic portions of the fallopian canal, and exposing the cochlea from the basal to the apical turn. Patients' recovery was uneventful, and long-term magnetic resonance imaging showed no residual tumor. Facial bridge cochleostomy can be a flexible extension of the translabyrinthine approach for tumors extending from the internal auditory canal to the cochlea. The transcanal approach is suitable for the primary exclusive intralabyrinthine tumor. The indications for the different approaches are discussed.

Perilymph sampling from the cochlear apex: a reliable method to obtain higher purity perilymph samples from scala tympani.

PubMed

Salt, Alec N; Hale, Shane A; Plonkte, Stefan K R

2006-05-15

Measurements of drug levels in the fluids of the inner ear are required to establish kinetic parameters and to determine the influence of specific local delivery protocols. For most substances, this requires cochlear fluids samples to be obtained for analysis. When auditory function is of primary interest, the drug level in the perilymph of scala tympani (ST) is most relevant, since drug in this scala has ready access to the auditory sensory cells. In many prior studies, ST perilymph samples have been obtained from the basal turn, either by aspiration through the round window membrane (RWM) or through an opening in the bony wall. A number of studies have demonstrated that such samples are likely to be contaminated with cerebrospinal fluid (CSF). CSF enters the basal turn of ST through the cochlear aqueduct when the bony capsule is perforated or when fluid is aspirated. The degree of sample contamination has, however, not been widely appreciated. Recent studies have shown that perilymph samples taken through the round window membrane are highly contaminated with CSF, with samples greater than 2microL in volume containing more CSF than perilymph. In spite of this knowledge, many groups continue to sample from the base of the cochlea, as it is a well-established method. We have developed an alternative, technically simple method to increase the proportion of ST perilymph in a fluid sample. The sample is taken from the apex of the cochlea, a site that is distant from the cochlear aqueduct. A previous problem with sampling through a perforation in the bone was that the native perilymph rapidly leaked out driven by CSF pressure and was lost to the middle ear space. We therefore developed a procedure to collect all the fluid that emerged from the perforated apex after perforation. We evaluated the method using a marker ion trimethylphenylammonium (TMPA). TMPA was applied to the perilymph of guinea pigs either by RW irrigation or by microinjection into the apical turn. The TMPA concentration of the fluid sample was compared with that measured in perilymph prior to taking the sample using a TMPA-selective microelectrode sealed into ST. Data were interpreted with a finite element model of the cochlear fluids that was used to simulate each aspect of the experiment. The correction of sample concentration back to the perilymph concentration prior to sampling can be performed based on the known ST volume (4.7microL in the guinea pig) and the sample volume. A more precise correction requires some knowledge of the profile of drug distribution along the cochlear prior to sampling. This method of sampling from the apex is technically simple and provides a larger sample volume with a greater proportion of perilymph compared to sampling through the RW.

Perilymph Sampling from the Cochlear Apex: A Reliable Method to Obtain Higher Purity Perilymph Samples from Scala Tympani

PubMed Central

Salt, Alec N.; Hale, Shane A.; Plontke, Stefan K. R.

2006-01-01

Measurements of drug levels in the fluids of the inner ear are required to establish kinetic parameters and to determine the influence of specific local delivery protocols. For most substances, this requires cochlear fluids samples to be obtained for analysis. When auditory function is of primary interest, the drug level in the perilymph of scala tympani (ST) is most relevant, since drug in this scala has ready access to the auditory sensory cells. In many prior studies, ST perilymph samples have been obtained from the basal turn, either by aspiration through the round window membrane (RWM) or through an opening in the bony wall. A number of studies have demonstrated that such samples are likely to be contaminated with cerebrospinal fluid (CSF). CSF enters the basal turn of ST through the cochlear aqueduct when the bony capsule is perforated or when fluid is aspirated. The degree of sample contamination has, however, not been widely appreciated. Recent studies have shown that perilymph samples taken through the round window membrane are highly contaminated with CSF, with samples greater than 2 μL in volume containing more CSF than perilymph. In spite of this knowledge, many groups continue to sample from the base of the cochlea, as it is a well-established method. We have developed an alternative, technically simple method to increase the proportion of ST perilymph in a fluid sample. The sample is taken from the apex of the cochlea, a site that is distant from the cochlear aqueduct. A previous problem with sampling through a perforation in the bone was that the native perilymph rapidly leaked out driven by CSF pressure and was lost to the middle ear space. We therefore developed a procedure to collect all the fluid that emerged from the perforated apex after perforation. We evaluated the method using a marker ion trimethylphenylammonium (TMPA). TMPA was applied to the perilymph of guinea pigs either by RW irrigation or by microinjection into the apical turn. The TMPA concentration of the fluid sample was compared with that measured in perilymph prior to taking the sample using a TMPA-selective microelectrode sealed into ST. Data were interpreted with a finite element model of the cochlear fluids that was used to simulate each aspect of the experiment. The correction of sample concentration back to the perilymph concentration prior to sampling can be performed based on the known ST volume (4.7 μL in the guinea pig) and the sample volume. A more precise correction requires some knowledge of the profile of drug distribution along the cochlear prior to sampling. This method of sampling from the apex is technically simple and provides a larger sample volume with a greater proportion of perilymph compared to sampling through the RW. PMID:16310856

In vivo imaging of mammalian cochlear blood flow using fluorescence microendoscopy.

PubMed

Monfared, Ashkan; Blevins, Nikolas H; Cheung, Eunice L M; Jung, Juergen C; Popelka, Gerald; Schnitzer, Mark J

2006-02-01

We sought to develop techniques for visualizing cochlear blood flow in live mammalian subjects using fluorescence microendoscopy. Inner ear microcirculation appears to be intimately involved in cochlear function. Blood velocity measurements suggest that intense sounds can alter cochlear blood flow. Disruption of cochlear blood flow may be a significant cause of hearing impairment, including sudden sensorineural hearing loss. However, inability to image cochlear blood flow in a nondestructive manner has limited investigation of the role of inner ear microcirculation in hearing function. Present techniques for imaging cochlear microcirculation using intravital light microscopy involve extensive perturbations to cochlear structure, precluding application in human patients. The few previous endoscopy studies of the cochlea have suffered from optical resolution insufficient for visualizing cochlear microvasculature. Fluorescence microendoscopy is an emerging minimally invasive imaging modality that provides micron-scale resolution in tissues inaccessible to light microscopy. In this article, we describe the use of fluorescence microendoscopy in live guinea pigs to image capillary blood flow and movements of individual red blood cells within the basal turn of the cochlea. We anesthetized eight adult guinea pigs and accessed the inner ear through the mastoid bulla. After intravenous injection of fluorescein dye, we made a limited cochleostomy and introduced a compound doublet gradient refractive index endoscope probe 1 mm in diameter into the inner ear. We then imaged cochlear blood flow within individual vessels in an epifluorescence configuration using one-photon fluorescence microendoscopy. We observed single red blood cells passing through individual capillaries in several cochlear structures, including the round window membrane, spiral ligament, osseous spiral lamina, and basilar membrane. Blood flow velocities within inner ear capillaries varied widely, with observed speeds reaching up to approximately 500 microm/s. Fluorescence microendoscopy permits visualization of cochlear microcirculation with micron-scale optical resolution and determination of blood flow velocities through analysis of video sequences.

Auditory brainstem activity and development evoked by apical versus basal cochlear implant electrode stimulation in children.

PubMed

Gordon, K A; Papsin, B C; Harrison, R V

2007-08-01

The role of apical versus basal cochlear implant electrode stimulation on central auditory development was examined. We hypothesized that, in children with early onset deafness, auditory development evoked by basal electrode stimulation would differ from that evoked more apically. Responses of the auditory nerve and brainstem, evoked by an apical and a basal implant electrode, were measured over the first year of cochlear implant use in 50 children with early onset severe to profound deafness who used hearing aids prior to implantation. Responses at initial stimulation were of larger amplitude and shorter latency when evoked by the apical electrode. No significant effects of residual hearing or age were found on initial response amplitudes or latencies. With implant use, responses evoked by both electrodes showed decreases in wave and interwave latencies reflecting decreased neural conduction time through the brainstem. Apical versus basal differences persisted with implant experience with one exception; eIII-eV interlatency differences decreased with implant use. Acute stimulation shows prolongation of basally versus apically evoked auditory nerve and brainstem responses in children with severe to profound deafness. Interwave latencies reflecting neural conduction along the caudal and rostral portions of the brainstem decreased over the first year of implant use. Differences in neural conduction times evoked by apical versus basal electrode stimulation persisted in the caudal but not rostral brainstem. Activity-dependent changes of the auditory brainstem occur in response to both apical and basal cochlear implant electrode stimulation.

Scala tympani measurement.

PubMed

Walby, A P

1985-01-01

The length and cross-sectional height of the scala tympani are relevant to the design of cochlear implants. The lengths and heights of the scalae tympani in ten pairs of serially sectioned temporal bones were measured by an adaptation of the serial section method of cochlear reconstruction. The study found the middle segments of individual pairs of scalae tympani to be very similar in height, but each pair varied slightly from other pairs. The height decreased overall from the base to the apex, but there was a small expansion at the junction of the basal and middle turns where the interscalar septum originated. The theoretical relationships of different diameter electrodes to the organ of Corti were plotted for one cochlea. The size of the electrode and the path it followed were shown in theory to alter considerably its position in relation to the organ of Corti.

Motion of organ of Corti structures in the gerbil cochlear apex, measured with a commercial optical coherence tomography (OCT) system

NASA Astrophysics Data System (ADS)

Ravicz, Michael E.; Cho, Nam-Hyun; Maftoon, Nima; Puria, Sunil

2018-05-01

Recent developments in Optical Coherence Tomography (OCT) allow measurements of cochlear motions through the bony cochlear wall without holes at spatial resolutions approaching about 10 µm. Measurements to date have been made with custom OCT systems with long development times. We present measurements made with a commercial OCT system driven by custom software (VibOCT) that facilitates near real-time frequency response measurements. The 905-nm wavelength laser and high-speed (100 kHz) camera provide higher axial resolution (3 µm in air) and temporal resolution than previous studies and a sub-nanometer noise floor in air. We gathered anatomical images of the gerbil cochlear apex in vivo at higher resolution than available previously, sufficient to resolve individual outer hair cells, pillar cells, tunnel of Corti and inner sulcus regions. Images from the 3rd apical turn show a bulging of Reissners membrane in vivo that flattened post-mortem with a concomitant reduction in the distance between the Henson cell border and the stria vascularis wall. Vibrometry of the organ of Corti shows a low-pass characteristic in-vivo and post-mortem with a traveling wave-like phase delay similar to a recent study rather than the sharp tuning seen more basally. This system can provide valuable information on cochlear function, which is also useful for the development of detailed cochlear models of the passive and active gerbil apex.

Intracochlear pressure measurements in scala media inform models of cochlear mechanics

NASA Astrophysics Data System (ADS)

Kale, Sushrut; Olson, Elizabeth S.

2015-12-01

In the classic view of cochlear mechanics, the cochlea is comprised of two identical fluid chambers separated by the cochlear partition (CP). In this view the traveling wave pressures in the two chambers mirror each other; they are equal in magnitude and opposite in phase. A fast pressure mode adds approximately uniformly. More recent models of cochlear mechanics take into account the structural complexity of the CP and the resulting additional mechanical modes would lead to distinct (non-symmetric) patterns of pressure and motion on the two sides of the CP. However, there was little to no physiological data that explored these predictions. To this aim, we measured intracochlear fluid pressure in scala media (SM), including measurements close to the sensory tissue, using miniaturized pressure sensors (˜ 80 μm outer diameter). Measurements were made in-vivo from the basal cochlear turn in gerbils. SM pressure was measured at two longitudinal locations in different preparations. In a subset of the experiments SM and ST (scala tympani) pressures were measured at the same longitudinal location. Traveling wave pressures were observed in both SM and ST, and showed the relative phase predicted by the classical theory. In addition, SM pressure showed spatial variations that had not been observed in ST, which points to a relatively complex CP motion on the SM side. These data both underscore the first-order validity of the classic cochlear traveling wave model, and open a new view to CP mechanics.

Gentamicin concentration gradients in scala tympani perilymph following systemic applications.

PubMed

Hahn, Hartmut; Salt, Alec N; Schumacher, Ulrike; Plontke, Stefan K

2013-01-01

It has been shown in prior studies that round window membrane (RWM) application of gentamicin produced a robust basal-apical concentration gradient in the perilymph of scala tympani (ST) with peak concentrations in the basal turn of ST. These gradients potentially contribute to the clinical efficacy and safety of intratympanic gentamicin applications for the treatment of Ménière's disease. The present study aimed to establish the distribution of gentamicin along ST perilymph after systemic applications. Gentamicin sulfate was applied intravenously in the amounts of 100, 300 and 600 mg/kg body weight (BW) over a period of 3 h or as a 300 mg/kg BW subcutaneous bolus injection. At 3 and 5 h after the start of the application perilymph of ST was aspirated from the cochlea apex of the right and left cochlea, respectively, and 10 sequential 1-µl perilymph samples from the apex of each cochlea were quantitatively analyzed using a fluorescence polarization immunoassay. In contrast to local RWM delivery, systemic application of gentamicin resulted in the highest perilymph levels in the apex of the cochlea with decreasing concentrations towards the basal regions of ST. The absolute gentamicin concentrations increased with the amount of drug applied and time before sampling. While it is likely that the basal-apical gradient measured after local drug applications to the round window niche is the result of the direct uptake of drugs into the perilymph of the ST, distribution by diffusion and a very low perilymph flow towards the cochlear apex, computer simulations suggested that the apical-basal gradient observed with these systemic applications can be explained by higher entry rates of gentamicin in the apex compared to the basal turns of the cochlea. It is also possible that gentamicin enters perilymph indirectly from the blood via the endolymph. In this case the faster kinetics in apical turns could be due to the smaller cross-sectional area of ST relative to endolymph in the apical turns. © 2013 S. Karger AG, Basel.

Anatomical evidence for low frequency sensitivity in an archaeocete whale: comparison of the inner ear of Zygorhiza kochii with that of crown Mysticeti.

PubMed

Ekdale, Eric G; Racicot, Rachel A

2015-01-01

The evolution of hearing in cetaceans is a matter of current interest given that odontocetes (toothed whales) are sensitive to high frequency sounds and mysticetes (baleen whales) are sensitive to low and potentially infrasonic noises. Earlier diverging stem cetaceans (archaeocetes) were hypothesized to have had either low or high frequency sensitivity. Through CT scanning, the morphology of the bony labyrinth of the basilosaurid archaeocete Zygorhiza kochii is described and compared to novel information from the inner ears of mysticetes, which are less known than the inner ears of odontocetes. Further comparisons are made with published information for other cetaceans. The anatomy of the cochlea of Zygorhiza is in line with mysticetes and supports the hypothesis that Zygorhiza was sensitive to low frequency noises. Morphological features that support the low frequency hypothesis and are shared by Zygorhiza and mysticetes include a long cochlear canal with a high number of turns, steeply graded curvature of the cochlear spiral in which the apical turn is coiled tighter than the basal turn, thin walls separating successive turns that overlap in vestibular view, and reduction of the secondary bony lamina. Additional morphology of the vestibular system indicates that Zygorhiza was more sensitive to head rotations than extant mysticetes are, which likely indicates higher agility in the ancestral taxon. © 2014 Anatomical Society.

Anatomical evidence for low frequency sensitivity in an archaeocete whale: comparison of the inner ear of Zygorhiza kochii with that of crown Mysticeti

PubMed Central

Ekdale, Eric G; Racicot, Rachel A

2015-01-01

The evolution of hearing in cetaceans is a matter of current interest given that odontocetes (toothed whales) are sensitive to high frequency sounds and mysticetes (baleen whales) are sensitive to low and potentially infrasonic noises. Earlier diverging stem cetaceans (archaeocetes) were hypothesized to have had either low or high frequency sensitivity. Through CT scanning, the morphology of the bony labyrinth of the basilosaurid archaeocete Zygorhiza kochii is described and compared to novel information from the inner ears of mysticetes, which are less known than the inner ears of odontocetes. Further comparisons are made with published information for other cetaceans. The anatomy of the cochlea of Zygorhiza is in line with mysticetes and supports the hypothesis that Zygorhiza was sensitive to low frequency noises. Morphological features that support the low frequency hypothesis and are shared by Zygorhiza and mysticetes include a long cochlear canal with a high number of turns, steeply graded curvature of the cochlear spiral in which the apical turn is coiled tighter than the basal turn, thin walls separating successive turns that overlap in vestibular view, and reduction of the secondary bony lamina. Additional morphology of the vestibular system indicates that Zygorhiza was more sensitive to head rotations than extant mysticetes are, which likely indicates higher agility in the ancestral taxon. PMID:25400023

Clustering is a feature of the spiral ganglion in the basal turn.

PubMed

Gacek, Richard R

2012-01-01

To demonstrate the organization of the spiral ganglion in the mammalian species. Temporal bone (TB) specimens from man (n = 2), monkey (n = 2), lion (n = 2) and cat (n = 20) were stained, decalcified and dissected according to the Sudan black B method of Rasmussen. These TB specimens were examined under a Zeiss operating microscope and photographed with a Canon 100 camera interfaced with the microscope. Spiral ganglion cells occurred in clusters within Rosenthal's canal in all four species. The location of the clusters was marked by the interface between axon and dendritic bundles as well as groups of ganglion cells. In monkey and man the clusters were more separated than in lion and cat. These observations indicate that the spiral ganglion forms clusters of neurons within Rosenthal's canal at the basal cochlear turn in the mammals investigated here. The formation of clusters may be related to the principles of neurogenesis. Copyright © 2011 S. Karger AG, Basel.

The cochlear size of bats and rodents derived from MRI images and histology.

PubMed

Hsiao, Chun Jen; Jen, Philip Hung-Sun; Wu, Chung Hsin

2015-05-27

From the evolutionary perspective, the ear of each animal species is built for effective processing of the biologically relevant signals used for communication and acoustically guided orientation. Because the sound pulses used by echolocating bats for orientation and rodents for communication are quite different, the basic design of the mammalian auditory system commonly shared by echolocating bats must be specialized in some manner to effectively process their species-specific sounds. The present study examines the difference in the cochlea of these animal species using MRI images and histological techniques. We report here that, although all these animal species share a similar cochlear structure, they vary in their cochlear size and turns. Bats using constant frequency-frequency-modulated pulses (CF-FM bats) and frequency-modulated pulses (FM bats) for echolocation have a larger cochlear size and more cochlear turns than rodents (mice and rats). However, CF-FM bats have the largest cochlear size and most cochlear turns. This difference in cochlear size and turns of these animal species is discussed in relation to their biologically relevant sounds and acoustic behavior.

[The effect of nimodipine on cochlear blood flow in the guinea pig].

PubMed

Meyer, P; Werner, E; Schmidt, R; Grützmacher, W; Gehrig, W; Seuter, F

1994-10-01

The influence of nimodipine (Nimotop, CAS 66085-59-4), a selectively cerebrovascularly acting 1,4-dihydropyridine calcium antagonist, on the cochlear blood flow (CBF) was studied in 19 guinea pigs (6 controls). The hydrogen clearance measurements were carried out under alpha-chloralose-ethylurethane anaesthesia, artificial respiration with simultaneous control of electrocardiogram, blood pressure, body temperature and arterial pH (hourly). The indirect measurement of CBF was carried out by means of hydrogen clearance in the perilymphatic space (basal turn) before and after intravenous application of 1 microgram nimodipine/kg/min. The mean arterial blood pressure remained within the +/- 5% range of the initial value during the experiment. Under treatment with nimodipine the CBF showed a non-significant average increase of 4.69% and under placebo (20% ethanol, 17% polyethylenglycol 400, citrate buffer), a non-significant average decrease of 6.16%. The influence of nimodipine on CBF was underlined by the overcompensation of the placebo effect.

Factors influencing the efficacy of round window dexamethasone protection of residual hearing post-cochlear implant surgery.

PubMed

Chang, Andrew; Eastwood, Hayden; Sly, David; James, David; Richardson, Rachael; O'Leary, Stephen

2009-09-01

To protect hearing in an experimental model of cochlear implantation by the application of dexamethasone to the round window prior to surgery. The present study examined the dosage and timing relationships required to optimise the hearing protection. Dexamethasone or saline (control) was absorbed into a pledget of the carboxymethylcellulose and hyaluronic acid and applied to the round window of the guinea pig prior to cochlear implantation. The treatment groups were 2% w/v dexamethasone for 30, 60 and 120min; 20% dexamethasone applied for 30min. Auditory sensitivity was determined pre-operatively, and at 1 week after surgery, with pure-tone auditory brainstem response audiometry (2-32kHz). Cochlear implantation was performed via a cochleostomy drilled into the basal turn of the cochlea, into which a miniature cochlear implant dummy electrode was inserted using soft-surgery techniques. ABR thresholds were elevated after cochlear implantation, maximally at 32kHz and to a lesser extent at lower frequencies. Thresholds were less elevated after dexamethasone treatment, and the hearing protection improved when 2% dexamethasone was applied to the round window for longer periods of time prior to implantation. The time that dexamethasone need be applied to achieve hearing protection could be reduced by increasing the concentration of steroid, with a 20% application for 30min achieving similar levels of protection to a 60min application of 2% dexamethasone. Hearing protection is improved by increasing the time that dexamethasone is applied to the round window prior to cochlear implantation, and the waiting time can be reduced by increasing the steroid concentration. These results suggest that the diffusion dexamethasone through the cochlea is the prime determinant of the extent of hearing protection.

Gentamicin concentration gradients in scala tympani perilymph following systemic applications

PubMed Central

Hahn, Hartmut; Salt, Alec N.; Schumacher, Ulrike; Plontke, Stefan K.

2013-01-01

In prior studies it was shown that round window membrane (RWM) application of gentamicin produced a robust baso-apical concentration gradient in the perilymph of scala tympani (ST) with peak concentrations in the basal turn of ST. These gradients potentially contribute to the clinical efficacy and safety of intratympanic gentamicin applications for the treatment of Meniere’s disease. The present study aimed to establish the distribution of gentamicin along ST perilymph after systemic applications. Gentamicin sulfate was applied intravenously in the amounts of 100, 300 and 600 mg/kg/bw over a period of three hours or as a 300 mg/kg/bw subcutaneous bolus injection. Three and five hours after the start of the application perilymph of ST was aspirated from the cochlea apex of the right and left cochlea, respectively. Ten sequential 1 μL-perilymph samples from the apex of each cochlea were quantitatively analyzed using a fluorescence polarization immunoassay. In contrast to local RWM delivery, systemic application of gentamicin resulted in highest perilymph levels in the apex of the cochlea with decreasing concentrations towards the basal regions of ST. The absolute gentamicin concentrations increased with amount of drug applied and time before sampling. While the basal-apical gradient measured after local drug applications to the RW niche is likely the result of the direct uptake of drugs into the perilymph of the ST, distribution by diffusion and a very low perilymph flow towards the cochlear apex, computer simulations suggested that the apical-basal gradient observed with these systemic applications can be explained by higher entry rates of gentamicin in the apex compared to the basal turns of the cochlea. It is also possible that gentamicin enters perilymph indirectly from blood via the endolymph. In this case the faster kinetics in apical turns could be due to the smaller cross-sectional area of scala tympani relative to endolymph in the apical turns. PMID:24192668

The Effect of Scala Tympani Morphology on Basilar Membrane Contact With a Straight Electrode Array: A Human Temporal Bone Study.

PubMed

Verberne, Juul; Risi, Frank; Campbell, Luke; Chambers, Scott; O'Leary, Stephen

2017-01-01

Scala tympani morphology influences the insertion dynamics and intra-scalar position of straight electrode arrays. Hearing preservation is the goal of cochlear implantation with current thin straight electrode arrays. These hug the lateral wall, facilitating full, atraumatic insertions. However, most studies still report some postoperative hearing loss. This study explores the influence of scala tympani morphology on array position relative to the basilar membrane and its possible contribution to postoperative hearing loss. Twenty-six fresh-frozen human temporal bones implanted with a straight electrode array were three-dimensionally reconstructed from micro-photographic histological sections. Insertion depth and the proximity between the array and basilar membrane were recorded. Lateral wall shape was quantified as a curvature ratio. Insertion depths ranged from 233 to 470 degrees. The mean first point of contact between the array and basilar membrane was 185 degrees; arrays tended to remain in contact with the membrane after first contacting it. Eighty-nine and 93% of arrays that reached the upper basal (>240-360 degrees) and second (>360-720 degrees) turns respectively contacted the basilar membrane in these regions. Scalar wall curvature ratio decreased significantly (the wall became steeper) from the basal to second turns. This shift correlated with a reduced distance between the array and basilar membrane. Scala tympani morphology influences the insertion dynamics and intra-scalar position of a straight electrode array. In addition to gross trauma of cochlear structures, contact between the array and basilar membrane and how this impacts membrane function should be considered in hearing preservation cases.

Cytomegalovirus (CMV) Infection Causes Degeneration of Cochlear Vasculature and Hearing Loss in a Mouse Model.

PubMed

Carraro, Mattia; Almishaal, Ali; Hillas, Elaine; Firpo, Matthew; Park, Albert; Harrison, Robert V

2017-04-01

Cytomegalovirus (CMV) infection is one of the most common causes of congenital hearing loss in children. We have used a murine model of CMV infection to reveal functional and structural cochlear pathogenesis. The cerebral cortex of Balb/c mice (Mus musculus) was inoculated with 2000 pfu (plaque forming units) of murine CMV on postnatal day 3. At 6 weeks of age, cochlear function was monitored using auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) measures. Histological assessment of cochlear vasculature using a corrosion cast technique was made at 8 weeks. Vascular casts of mCMV-damaged cochleas, and those of untreated control animals, were examined using scanning electron microscopy. We find very large variations in the degree of vascular damage in animals given identical viral injections (2000 pfu). The primary lesion caused by CMV infection is to the stria vascularis and to the adjacent spiral limbus capillary network. Capillary beds of the spiral ligament are generally less affected. The initial vascular damage is found in the mid-apical turn and appears to progress to more basal cochlear regions. After viral migration to the inner ear, the stria vascularis is the primary affected structure. We suggest that initial auditory threshold losses may relate to the poor development or maintenance of the endocochlear potential caused by strial dysfunction. Our increased understanding of the pathogenesis of CMV-related hearing loss is important for defining methods for early detection and treatment.

A new computed tomography method to identify meningitis-related cochlear ossification and fibrosis before cochlear implantation.

PubMed

Ichikawa, Kazunori; Kashio, Akinori; Mori, Harushi; Ochi, Atushi; Karino, Shotaro; Sakamoto, Takashi; Kakigi, Akinobu; Yamasoba, Tatsuya

2014-04-01

To develop a new method to determine the presence of intracochlear ossification and/or fibrosis in cochlear implantation candidates with bilateral profound deafness following meningitis. Diagnostic test assessment. A university hospital. This study involved 15 ears from 13 patients with profound deafness following meningitis who underwent cochlear implantation. These ears showed normal structures, soft tissue, partial bony occlusion, and complete bony occlusion in 4, 3, 2, and 6 ears, respectively. We measured radiodensity in Hounsfield units (HU) using 0.5-mm-thick axial high-resolution computed tomography image slices at 3 different levels in the basal turn, the fenestration, and inferior and ascending segment sites, located along the electrode-insertion path. Pixel-level analysis on the DICOM viewer yielded actual computed tomography values of intracochlear soft tissues by eliminating the partial volume effect. The values were compared with the intraoperative findings. Values for ossification (n = 12) ranged from +547 HU to +1137 HU; for fibrosis (n = 11), from +154 HU to +574 HU; and for fluid (n = 22), from -49 HU to +255 HU. From these values, we developed 2 presets of window width (WW) and window level (WL): (1) WW: 1800, WL: 1100 (200 HU to 2000 HU) and (2) WW: 1500, WL: 1250 (500 HU to 2000 HU). The results using these 2 presets corresponded well to the intraoperative findings. Our new method is easy and feasible for preoperative determination of the presence of cochlear ossification and/or fibrosis that develops following meningitis.

Defining the Hook Region Anatomy of the Guinea Pig Cochlea for Modeling of Inner Ear Surgery.

PubMed

Lo, Jonathon; Sale, Phillip; Wijewickrema, Sudanthi; Campbell, Luke; Eastwood, Hayden; O'leary, Stephen John

2017-07-01

The aim of this study was to describe the hook region anatomy of the guinea pig cochlea to identify the optimal surgical approach for cochlear implantation and to determine what anatomical structures are at risk. Animal studies investigating hearing loss after cochlear implantation surgery are currently constrained by the lack of a reproducible implantation model. Guinea pig cochleae were imaged using thin-sheet laser imaging microscopy. Images were stitched, reconstructed, and segmented for analysis. Insertion vectors were determined by tracing their paths to the outer wall and converting to Cartesian coordinates. Spherical surface and multiplane views were generated to analyze outer wall and radial forces of the insertion vector. Thin-sheet laser imaging microscopy enabled quantitative, whole specimen analysis of the soft and bony tissue relationships of the complex cochlear hook region in any desired plane without loss of image quality. Round window or cochleostomy approaches in the anteroinferior plane avoided direct damage to cochlear structures. Cochleostomy approach had large interindividual variability of angular depth and outer wall forces but predictable radial force. The guinea pig hook region and lower basal turn have similar structural relationships to humans. Careful cochleostomy placement is essentially for minimizing cochlear trauma and for ensuring a straight insertion vector that successfully advances around the outer wall. Experiments with guinea pigs that control for the surgical approach are likely to provide useful insights into the aetiology and the development of therapies directed at postimplantation hearing loss.

Bacterial invasion of the inner ear in association with pneumococcal meningitis.

PubMed

Møller, Martin Nue; Brandt, Christian; Østergaard, Christian; Caye-Thomasen, Per

2014-06-01

To examine the pathways of bacterial invasion and subsequent spreading in the inner ear during pneumococcal meningitis. A well-established adult rat model of Streptococcus pneumoniae meningitis was used. Thirty rats were inoculated intrathecally with S. pneumoniae serotype 1, 3 or 9 V and received no additional treatment. The rats were sacrificed when reaching terminal illness or on Day 7 and then prepared for serial sectioning and PAS-Alcian blue staining for light microscopy. During the first few days after inoculation, bacteria invade the inner ear through the cochlear aqueduct, into the scala tympani of the cochlea (perilymphatic space). From here, bacteria spreads apically toward the helicotrema and subsequently basally through the scala vestibuli, toward the vestibule and the vestibular system. When the bacteria after 5 to 6 days had reached scala vestibuli of the basal turn of the cochlea, hematogenous spreading occurred to the spiral ligament and into the cochlear endolymph, subsequently to the vestibular endolymph. We found no evidence of alternative routes for bacterial invasion in the inner ear. Several internal barriers to bacterial spreading were found within the inner ear. Bacterial elimination was evidenced by engulfment by macrophages within the inner ear. From the meninges, pneumococci invade the inner ear through the cochlear aqueduct during the first days of infection, whereas hematogenous invasion via the spiral ligament capillary bed occur at later stages. Although internal barriers exist within the inner ear, the spreading of bacteria occurs via the natural pathways of the fluid compartments. Bacterial elimination occurs by local macrophage engulfment.

Spread of cochlear excitation during stimulation with pulsed infrared radiation: inferior colliculus measurements

NASA Astrophysics Data System (ADS)

Richter, C.-P.; Rajguru, S. M.; Matic, A. I.; Moreno, E. L.; Fishman, A. J.; Robinson, A. M.; Suh, E.; Walsh, J. T., Jr.

2011-10-01

Infrared neural stimulation (INS) has received considerable attention over the last few years. It provides an alternative method to artificially stimulate neurons without electrical current or the introduction of exogenous chromophores. One of the primary benefits of INS could be the improved spatial selectivity when compared with electrical stimulation. In the present study, we have evaluated the spatial selectivity of INS in the acutely damaged cochlea of guinea pigs and compared it to stimulation with acoustic tone pips in normal-hearing animals. The radiation was delivered via a 200 µm diameter optical fiber, which was inserted through a cochleostomy into the scala tympani of the basal cochlear turn. The stimulated section along the cochlear spiral ganglion was estimated from the neural responses recorded from the central nucleus of the inferior colliculus (ICC). ICC responses were recorded in response to cochlear INS using a multichannel penetrating electrode array. Spatial tuning curves (STCs) were constructed from the responses. For INS, approximately 55% of the activation profiles showed a single maximum, ~22% had two maxima and ~13% had multiple maxima. The remaining 10% of the profiles occurred at the limits of the electrode array and could not be classified. The majority of ICC STCs indicated that the spread of activation evoked by optical stimuli is comparable to that produced by acoustic tone pips.

Auditory Cortex Basal Activity Modulates Cochlear Responses in Chinchillas

PubMed Central

León, Alex; Elgueda, Diego; Silva, María A.; Hamamé, Carlos M.; Delano, Paul H.

2012-01-01

Background The auditory efferent system has unique neuroanatomical pathways that connect the cerebral cortex with sensory receptor cells. Pyramidal neurons located in layers V and VI of the primary auditory cortex constitute descending projections to the thalamus, inferior colliculus, and even directly to the superior olivary complex and to the cochlear nucleus. Efferent pathways are connected to the cochlear receptor by the olivocochlear system, which innervates outer hair cells and auditory nerve fibers. The functional role of the cortico-olivocochlear efferent system remains debated. We hypothesized that auditory cortex basal activity modulates cochlear and auditory-nerve afferent responses through the efferent system. Methodology/Principal Findings Cochlear microphonics (CM), auditory-nerve compound action potentials (CAP) and auditory cortex evoked potentials (ACEP) were recorded in twenty anesthetized chinchillas, before, during and after auditory cortex deactivation by two methods: lidocaine microinjections or cortical cooling with cryoloops. Auditory cortex deactivation induced a transient reduction in ACEP amplitudes in fifteen animals (deactivation experiments) and a permanent reduction in five chinchillas (lesion experiments). We found significant changes in the amplitude of CM in both types of experiments, being the most common effect a CM decrease found in fifteen animals. Concomitantly to CM amplitude changes, we found CAP increases in seven chinchillas and CAP reductions in thirteen animals. Although ACEP amplitudes were completely recovered after ninety minutes in deactivation experiments, only partial recovery was observed in the magnitudes of cochlear responses. Conclusions/Significance These results show that blocking ongoing auditory cortex activity modulates CM and CAP responses, demonstrating that cortico-olivocochlear circuits regulate auditory nerve and cochlear responses through a basal efferent tone. The diversity of the obtained effects suggests that there are at least two functional pathways from the auditory cortex to the cochlea. PMID:22558383

Effects of sustained release dexamethasone hydrogels in hearing preservation cochlear implantation.

PubMed

Honeder, Clemens; Zhu, Chengjing; Schöpper, Hanna; Gausterer, Julia Clara; Walter, Manuel; Landegger, Lukas David; Saidov, Nodir; Riss, Dominik; Plasenzotti, Roberto; Gabor, Franz; Arnoldner, Christoph

2016-11-01

It has been shown that glucocorticoids reduce the hearing threshold shifts associated with cochlear implantation. Previous studies evaluated the administration of glucocorticoids immediately before surgery or the repeated pre- or perioperative systemic application of glucocorticoids. The aim of this study was to evaluate the effects of a sustained release dexamethasone hydrogel in hearing preservation cochlear implantation. To address this issue, a guinea pig model of cochlear implantation was used. 30 normal hearing pigmented guinea pigs were randomized into a group receiving a single dose of a dexamethasone/poloxamer407 hydrogel one day prior to surgery, a second group receiving the hydrogel seven days prior to surgery and a control group. A silicone cochlear implant electrode designed for the use in guinea pigs was inserted to a depth of 5 mm through a cochleostomy. Compound action potentials of the auditory nerve (frequency range 0.5-32 kHz) were measured preoperatively, directly postoperatively and on postoperative days 3, 7, 14, 21 and 28. Following the last audiometry, temporal bones were harvested and histologically evaluated. Dexamethasone hydrogel application one day prior to surgery resulted in significantly reduced hearing threshold shifts at low, middle and high frequencies measured at postoperative day 28 (p < 0.05). Application of the hydrogel seven days prior to surgery did not show such an effect. Dexamethasone application one day prior to surgery resulted in increased outer hair cell counts in the cochlear apex and in reduced spiral ganglion cell counts in the basal and middle turn of the cochlea, a finding that was associated with a higher rate of electrode translocation in this group. In this study, we were able to demonstrate functional benefits of a single preoperative intratympanic application of a sustained release dexamethasone hydrogel in a guinea pig model of cochlear implantation. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

The consequences of neural degeneration regarding optimal cochlear implant position in scala tympani: a model approach.

PubMed

Briaire, Jeroen J; Frijns, Johan H M

2006-04-01

Cochlear implant research endeavors to optimize the spatial selectivity, threshold and dynamic range with the objective of improving the speech perception performance of the implant user. One of the ways to achieve some of these goals is by electrode design. New cochlear implant electrode designs strive to bring the electrode contacts into close proximity to the nerve fibers in the modiolus: this is done by placing the contacts on the medial side of the array and positioning the implant against the medial wall of scala tympani. The question remains whether this is the optimal position for a cochlea with intact neural fibers and, if so, whether it is also true for a cochlea with degenerated neural fibers. In this study a computational model of the implanted human cochlea is used to investigate the optimal position of the array with respect to threshold, dynamic range and spatial selectivity for a cochlea with intact nerve fibers and for degenerated nerve fibers. In addition, the model is used to evaluate the predictive value of eCAP measurements for obtaining peri-operative information on the neural status. The model predicts improved threshold, dynamic range and spatial selectivity for the peri-modiolar position at the basal end of the cochlea, with minimal influence of neural degeneration. At the apical end of the array (1.5 cochlear turns), the dynamic range and the spatial selectivity are limited due to the occurrence of cross-turn stimulation, with the exception of the condition without neural degeneration and with the electrode array along the lateral wall of scala tympani. The eCAP simulations indicate that a large P(0) peak occurs before the N(1)P(1) complex when the fibers are not degenerated. The absence of this peak might be used as an indicator for neural degeneration.

Evaluation of a new mid-scala cochlear implant electrode using microcomputed tomography.

PubMed

Frisch, Christopher D; Carlson, Matthew L; Lane, John I; Driscoll, Colin L W

2015-12-01

To investigate electrode position, depth of insertion, and electrode contact using an electrode array with a mid-scala design following round window (RW) and cochleostomy insertion. Eight fresh-frozen cadaveric bones were implanted; half via a RW approach and half through an anteroinferior cochleostomy using a styleted mid-scala electrode design. Microcomputed tomography was used to acquire oblique coronal and oblique axial reformations. Individual electrode positions along each array, insertional depth, and electrode contact were determined using National Institutes of Health Image J software. All electrodes were inserted without significant resistance. The average angular depth of insertion was 436.5° for the RW group and 422.7° for the cochleostomy group. All electrodes acquired a perimodiolar position in the proximal segment and a lateral wall position at the basal turn, regardless of approach. Electrodes distal to the basal turn demonstrated a variable location, with 78% mid scala. One cochleostomy array fractured through the interscalar partition (ISP), acquiring a scala vestibuli position. The odds ratio for either abutting the modiolus, ISP, lateral wall or floor, or fracturing through the ISP were 2.7 times more likely following a cochleostomy insertion (P = .032). The styleted mid-scala electrode design acquires a proximal perimodiolar position, a lateral wall location, as it traverses the basal turn, and most commonly a mid-scala position in the distal array. Interscalar excursion occurred in one of the cochleostomy insertions. Cochleostomy insertion is more likely to result in ultimate final electrode position adjacent to critical intracochlear structures. NA. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

Temporal bone borehole accuracy for cochlear implantation influenced by drilling strategy: an in vitro study.

PubMed

Kobler, Jan-Philipp; Schoppe, Michael; Lexow, G Jakob; Rau, Thomas S; Majdani, Omid; Kahrs, Lüder A; Ortmaier, Tobias

2014-11-01

Minimally invasive cochlear implantation is a surgical technique which requires drilling a canal from the mastoid surface toward the basal turn of the cochlea. The choice of an appropriate drilling strategy is hypothesized to have significant influence on the achievable targeting accuracy. Therefore, a method is presented to analyze the contribution of the drilling process and drilling tool to the targeting error isolated from other error sources. The experimental setup to evaluate the borehole accuracy comprises a drill handpiece attached to a linear slide as well as a highly accurate coordinate measuring machine (CMM). Based on the specific requirements of the minimally invasive cochlear access, three drilling strategies, mainly characterized by different drill tools, are derived. The strategies are evaluated by drilling into synthetic temporal bone substitutes containing air-filled cavities to simulate mastoid cells. Deviations from the desired drill trajectories are determined based on measurements using the CMM. Using the experimental setup, a total of 144 holes were drilled for accuracy evaluation. Errors resulting from the drilling process depend on the specific geometry of the tool as well as the angle at which the drill contacts the bone surface. Furthermore, there is a risk of the drill bit deflecting due to synthetic mastoid cells. A single-flute gun drill combined with a pilot drill of the same diameter provided the best results for simulated minimally invasive cochlear implantation, based on an experimental method that may be used for testing further drilling process improvements.

Surgical anatomy of the round window-Implications for cochlear implantation.

PubMed

Luers, J C; Hüttenbrink, K B; Beutner, D

2018-04-01

The round window is an important portal for the application of active hearing aids and cochlear implants. The anatomical and topographical knowledge about the round window region is a prerequisite for successful insertion for a cochlear implant electrode. To sum up current knowledge about the round window anatomy and to give advice to the cochlear implant surgeon for optimal placement of an electrode. Systematic Medline search. Search term "round window[Title]" with no date restriction. Only publications in the English Language were included. All abstracts were screened for relevance, that is a focus on surgical anatomy of the round window. The search results were supplemented with hand searching of selected reviews and reference lists from included studies. Subjective assessment. There is substantial variability in size and shape of the round window. The round window is regarded as the most reliable surgical landmark to safely locate the scala tympani. Factors affecting the optimal trajectory line for atraumatic electrode insertion are anatomy of the round window, the anatomy of the intracochlear hook region and the variable orientation and size of the cochlea's basal turn. The very close relation to the sensitive inner ear structures necessitates a thorough anatomic knowledge and careful insertion technique, especially when implanting patients with residual hearing. In order to avoid electrode migration between the scalae and to achieve protect the modiolus and the basilar membrane, it is recommended to aim for an electrode insertion vector from postero-superior to antero-inferior. © 2017 John Wiley & Sons Ltd.

Cochlear transducer operating point adaptation.

PubMed

Zou, Yuan; Zheng, Jiefu; Ren, Tianying; Nuttall, Alfred

2006-04-01

The operating point (OP) of outer hair cell (OHC) mechanotransduction can be defined as any shift away from the center position on the transduction function. It is a dc offset that can be described by percentage of the maximum transduction current or as an equivalent dc pressure in the ear canal. The change of OP can be determined from the changes of the second and third harmonics of the cochlear microphonic (CM) following a calibration of its initial value. We found that the initial OP was dependent on sound level and cochlear sensitivity. From CM generated by a lower sound level at 74 dB SPL to avoid saturation and suppression of basal turn cochlear amplification, the OHC OP was at constant 57% of the maximum transduction current (an ear canal pressure of -0.1 Pa). To perturb the OP, a constant force was applied to the bony shell of the cochlea at the 18 kHz best frequency location using a blunt probe. The force applied over the scala tympani induced an OP change as if the organ of Corti moved toward the scala vestibuli (SV) direction. During an application of the constant force, the second harmonic of the CM partially recovered toward the initial level, which could be described by two time constants. Removing the force induced recovery of the second harmonic to its normal level described by a single time constant. The force applied over the SV caused an opposite result. These data indicate an active mechanism for OHC transduction OP.

Displacements of the organ of Corti by gel injections into the cochlear apex

PubMed Central

Salt, Alec N.; Brown, Daniel J.; Hartsock, Jared J.; Plontke, Stefan K.

2009-01-01

In order to transduce sounds efficiently, the stereocilia of hair cells in the organ of Corti must be positioned optimally. Mechanical displacements, such as pressure differentials across the organ caused by endolymphatic hydrops, may impair sensitivity. Studying this phenomenon has been limited by the technical difficulty of inducing sustained displacements of stereocilia in vivo. We have found that small injections (0.5 to 2 μL) of Healon gel into the cochlear apex of guinea pigs produced sustained changes of endocochlear potential (EP), summating potential (SP) and transducer operating point (OP) in a manner consistent with a mechanically-induced position change of the organ of Corti in the basal turn. Induced changes immediately recovered when injection ceased. In addition, effects of low-frequency bias tones on EP, SP and OP were enhanced during the injection of gel and remained hypersensitive after injection ceased. This is thought to result from the viscous gel mechanically limiting pressure shunting through the helicotrema. Cochlear microphonics measured as frequency was varied showed enhancement below 100 Hz but most notably in the sub-auditory range. Sensitivity to low-frequency biasing was also enhanced in animals with surgically-induced endolymphatic hydrops, suggesting that obstruction of the perilymphatic space by hydrops could contribute to the pathophysiology of this condition. PMID:19217935

A novel perfusion-based method for cochlear implant electrode insertion.

PubMed

Kale, Sushrut; Cervantes, Vanessa M; Wu, Mailing R; Pisano, Dominic V; Sheth, Nakul; Olson, Elizabeth S

2014-08-01

A cochlear implant (CI) restores partial hearing to profoundly deaf individuals. CI electrodes are inserted manually in the cochlea and surgeons rely on tactile feedback from the implant to determine when to stop the insertion. This manual insertion method results in a large degree of variability in surgical outcomes and intra-cochlear trauma. Additionally, implants often span only the basal turn. In the present study we report on the development of a new method to assist CI electrode insertion. The design objectives are (1) an automated and standardized insertion technique across patients with (2) more apical insertion than is possible by the contemporary methods, while (3) minimizing insertion trauma. The method relies on a viscous fluid flow through the cochlea to carry the electrode array with it. A small cochleostomy (∼100-150 um in diameter) is made in scala vestibuli (SV) and the round window (RW) membrane is opened. A flow of diluted Sodium Hyaluronate (also known as Hyaluronic Acid, (HA)) is set up from the RW to the SV opening using a perfusion pump that sets up a unidirectional flow. Once the flow is established an implant is dropped into the ongoing flow. Here we present a proof-of-concept study where we used this technique to insert silicone implants all the way to the cochlear apex in rats and gerbils. In light-microscopic histology, the implantation occurred without cochlear trauma. To further assess the ototoxicity of the HA perfusion, we measured compound action potential (CAP) thresholds following the perfusion of HA, and found that the CAP thresholds were substantially elevated. Thus, at this point the method is promising, and requires further development to become clinically viable. Copyright © 2014 Elsevier B.V. All rights reserved.

Streptococcus pneumoniae-induced ototoxicity in organ of Corti explant cultures.

PubMed

Perny, Michael; Solyga, Magdalena; Grandgirard, Denis; Roccio, Marta; Leib, Stephen L; Senn, Pascal

2017-07-01

Hearing loss remains the most common long-term complication of pneumococcal meningitis (PM) reported in up to 30% of survivors. Streptococcus pneumoniae have been shown to possess different ototoxic properties. Here we present a novel ex vivo experimental setup to examine in detail the pattern of hair cell loss upon exposure to different S. pneumoniae strains, therefore recapitulating pathogen derived aspects of PM-induced hearing loss. Our results show a higher susceptibility towards S. pneumoniae-induced cochlear damage for outer hair cells (OHC) compared to inner hair cells (IHC), which is consistent with in vivo data. S. pneumoniae-induced hair cell loss was both time and dose-dependent. Moreover, we have found significant differences in the level of cell damage between tissue from the basal and the apical turns. This shows that the higher vulnerability of hair cells located at high frequency regions observed in vivo cannot be explained solely by the spatial organisation and bacterial infiltration from the basal portion of the cochlea. Using a wild type D39 strain and a mutant defective for the pneumolysin (PLY) gene, we also have shown that the toxin PLY is an important factor involved in ototoxic damages. The obtained results indicate that PLY can cause both IHC and OHC loss. Finally, we are reporting here for the first time a higher vulnerability of HC located at the basal and middle cochlear region to pneumolysin-induced damage. The detailed description of the susceptibility of hair cells to Streptococcus pneumoniae provided in this report can in the future determine the choice and the development of novel otoprotective therapies during pneumococcal meningitis. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Basilar membrane vibration is not involved in the reverse propagation of otoacoustic emissions

PubMed Central

He, W.; Ren, T.

2013-01-01

To understand how the inner ear-generated sound, i.e., otoacoustic emission, exits the cochlea, we created a sound source electrically in the second turn and measured basilar membrane vibrations at two longitudinal locations in the first turn in living gerbil cochleae using a laser interferometer. For a given longitudinal location, electrically evoked basilar membrane vibrations showed the same tuning and phase lag as those induced by sounds. For a given frequency, the phase measured at a basal location led that at a more apical location, indicating that either an electrical or an acoustical stimulus evoked a forward travelling wave. Under postmortem conditions, the electrically evoked emissions showed no significant change while the basilar membrane vibration nearly disappeared. The current data indicate that basilar membrane vibration was not involved in the backward propagation of otoacoustic emissions and that sounds exit the cochlea probably through alternative media, such as cochlear fluids. PMID:23695199

Development of a phase-sensitive Fourier domain optical coherence tomography system to measure mouse organ of Corti vibrations in two cochlear turns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramamoorthy, Sripriya; Zhang, Yuan; Jacques, Steven

In this study, we have developed a phase-sensitive Fourier-domain optical coherence tomography system to simultaneously measure the in vivo inner ear vibrations in the hook area and second turn of the mouse cochlea. This technical development will enable measurement of intra-cochlear distortion products at ideal locations such as the distortion product generation site and reflection site. This information is necessary to un-mix the complex mixture of intra-cochlear waves comprising the DPOAE and thus leads to the non-invasive identification of the local region of cochlear damage.

Perceptually aligning apical frequency regions leads to more binaural fusion of speech in a cochlear implant simulation.

PubMed

Staisloff, Hannah E; Lee, Daniel H; Aronoff, Justin M

2016-07-01

For bilateral cochlear implant users, the left and right arrays are typically not physically aligned, resulting in a degradation of binaural fusion, which can be detrimental to binaural abilities. Perceptually aligning the two arrays can be accomplished by disabling electrodes in one ear that do not have a perceptually corresponding electrode in the other side. However, disabling electrodes at the edges of the array will cause compression of the input frequency range into a smaller cochlear extent, which may result in reduced spectral resolution. An alternative approach to overcome this mismatch would be to only align one edge of the array. By aligning either only the apical or basal end of the arrays, fewer electrodes would be disabled, potentially causing less reduction in spectral resolution. The goal of this study was to determine the relative effect of aligning either the basal or apical end of the electrode with regards to binaural fusion. A vocoder was used to simulate cochlear implant listening conditions in normal hearing listeners. Speech signals were vocoded such that the two ears were either predominantly aligned at only the basal or apical end of the simulated arrays. The experiment was then repeated with a spectrally inverted vocoder to determine whether the detrimental effects on fusion were related to the spectral-temporal characteristics of the stimuli or the location in the cochlea where the misalignment occurred. In Experiment 1, aligning the basal portion of the simulated arrays led to significantly less binaural fusion than aligning the apical portions of the simulated array. However, when the input was spectrally inverted, aligning the apical portion of the simulated array led to significantly less binaural fusion than aligning the basal portions of the simulated arrays. These results suggest that, for speech, with its predominantly low frequency spectral-temporal modulations, it is more important to perceptually align the apical portion of the array to better preserve binaural fusion. By partially aligning these arrays, cochlear implant users could potentially increase their ability to fuse speech sounds presented to the two ears while maximizing spectral resolution. Copyright © 2016 Elsevier B.V. All rights reserved.

Evidence for basal distortion-product otoacoustic emission components.

PubMed

Martin, Glen K; Stagner, Barden B; Lonsbury-Martin, Brenda L

2010-05-01

Distortion-product otoacoustic emissions (DPOAEs) were measured with traditional DP-grams and level/phase (L/P) maps in rabbits with either normal cochlear function or unique sound-induced cochlear losses that were characterized as either low-frequency or notched configurations. To demonstrate that emission generators distributed basal to the f(2) primary-tone contribute, in general, to DPOAE levels and phases, a high-frequency interference tone (IT) was presented at 1/3 of an octave (oct) above the f(2) primary-tone, and DPOAEs were re-measured as "augmented" DP-grams (ADP-grams) and L/P maps. The vector difference between the control and augmented functions was then computed to derive residual DP-grams (RDP-grams) and L/P maps. The resulting RDP-grams and L/P maps, which described the DPOAEs removed by the IT, supported the notion that basal DPOAE components routinely contribute to the generation of standard measures of DPOAEs. Separate experiments demonstrated that these components could not be attributed to the effects of the 1/3-oct IT on f(2), or DPOAEs generated by the addition of a third interfering tone. These basal components can "fill in" the lesion estimated by the commonly employed DP-gram. Thus, ADP-grams more accurately reveal the pattern of cochlear damage and may eventually lead to an improved DP-gram procedure.

Listening to the ear

NASA Astrophysics Data System (ADS)

Shera, Christopher A.

Otoacoustic emissions demonstrate that the ear creates sound while listening to sound, offering a promising acoustic window on the mechanics of hearing in awake, listening human beings. That window is clouded, however, by an incomplete knowledge of wave reflection and transmission, both forth and back within the cochlea and through the middle ear. This thesis "does windows," addressing wave propagation and scattering on both sides of the middle ear. A summary of highlights follows. Measurements of the cochlear input impedance in cat are used to identify a new symmetry in cochlear mechanics-termed "tapering symmetry" after its geometric interpretation in simple models-that guarantees that the wavelength of the traveling wave changes slowly with position near the stapes. Waves therefore propagate without reflection through the basal turns of the cochlea. Analytic methods for solving the cochlear wave equations using a perturbative scattering series are given and used to demonstrate that, contrary to common belief, conventional cochlear models exhibit negligible internal reflection whether or not they accurately represent the tapering symmetries of the inner ear. Frameworks for the systematic "deconstruction" of eardrum and middle-ear transduction characteristics are developed and applied to the analysis of noninvasive measurements of middle-ear and cochlear mechanics. A simple phenomenological model of inner-ear compressibility that correctly predicts hearing thresholds in patients with missing or disarticulated middle-ear ossicles is developed and used to establish an upper bound on cochlear compressibility several orders of magnitude smaller than that provided by direct measurements. Accurate measurements of stimulus frequency evoked otoacoustic emissions are performed and used to determine the form and frequency variation of the cochlear traveling-wave ratio noninvasively. Those measurements are inverted to obtain the spatial distribution of mechanical inhomogeneities responsible for evoked emission. Although current models require that the periodicities found in emission spectra and threshold hearing curves originate in a corresponding corrugation in the mechanics of the cochlea, it is shown that the observed spectral periodicities can arise spontaneously through the dynamics of wave propagation and reflection and that the organ of Corti, as suggested by the anatomy, need manifest no particular translational symmetries.

Listening to the Ear

NASA Astrophysics Data System (ADS)

Shera, Christopher Alan

Otoacoustic emissions demonstrate that the ear creates sound while listening to sound, offering a promising acoustic window on the mechanics of hearing in awake, listening human beings. That window is clouded, however, by an incomplete knowledge of wave reflection and transmission, both forth and back within the cochlea and through the middle ear. This thesis "does windows," addressing wave propagation and scattering on both sides of the middle ear. A summary of highlights follows. Measurements of the cochlear input impedance in cat are used to identify a new symmetry in cochlear mechanics--termed "tapering symmetry" after its geometric interpretation in simple models--that guarantees that the wavelength of the traveling wave changes slowly with position near the stapes. Waves therefore propagate without reflection through the basal turns of the cochlea. Analytic methods for solving the cochlear wave equations using a perturbative scattering series are given and used to demonstrate that, contrary to common belief, conventional cochlear models exhibit negligible internal reflection whether or not they accurately represent the tapering symmetries of the inner ear. Frameworks for the systematic "deconstruction" of eardrum and middle-ear transduction characteristics are developed and applied to the analysis of noninvasive measurements of middle-ear and cochlear mechanics. A simple phenomenological model of inner-ear compressibility that correctly predicts hearing thresholds in patients with missing or disarticulated middle-ear ossicles is developed and used to establish an upper bound on cochlear compressibility several orders of magnitude smaller than that provided by direct measurements. Accurate measurements of stimulus -frequency evoked otoacoustic emissions are performed and used to determine the form and frequency variation of the cochlear traveling-wave ratio noninvasively. Those measurements are inverted to obtain the spatial distribution of mechanical inhomogeneities responsible for evoked emission. Although current models require that the periodicities found in emission spectra and threshold hearing curves originate in a corresponding corrugation in the mechanics of the cochlea, it is shown that the observed spectral periodicities can arise spontaneously through the dynamics of wave propagation and reflection and that the organ of Corti, as suggested by the anatomy, need manifest no particular translational symmetries.

Determination of drill paths for percutaneous cochlear access accounting for target positioning error

NASA Astrophysics Data System (ADS)

Noble, Jack H.; Warren, Frank M.; Labadie, Robert F.; Dawant, Benoit; Fitzpatrick, J. Michael

2007-03-01

In cochlear implant surgery an electrode array is permanently implanted to stimulate the auditory nerve and allow deaf people to hear. Current surgical techniques require wide excavation of the mastoid region of the temporal bone and one to three hours time to avoid damage to vital structures. Recently a far less invasive approach has been proposed-percutaneous cochlear access, in which a single hole is drilled from skull surface to the cochlea. The drill path is determined by attaching a fiducial system to the patient's skull and then choosing, on a pre-operative CT, an entry point and a target point. The drill is advanced to the target, the electrodes placed through the hole, and a stimulator implanted at the surface of the skull. The major challenge is the determination of a safe and effective drill path, which with high probability avoids specific vital structures-the facial nerve, the ossicles, and the external ear canal-and arrives at the basal turn of the cochlea. These four features lie within a few millimeters of each other, the drill is one millimeter in diameter, and errors in the determination of the target position are on the order of 0.5mm root-mean square. Thus, path selection is both difficult and critical to the success of the surgery. This paper presents a method for finding optimally safe and effective paths while accounting for target positioning error.

Measurement of cochlear length using the 'A' value for cochlea basal diameter: A feasibility study.

PubMed

Deep, Nicholas L; Howard, Brittany E; Holbert, Sarah O; Hoxworth, Joseph M; Barrs, David M

2017-07-01

To determine whether the cochlea basal diameter (A value) measurement can be consistently and precisely obtained from high-resolution temporal bone imaging for use in cochlear length estimation. A feasibility study at a tertiary referral center was performed using the temporal bone CTs of 40 consecutive patients. The distance from the round window to the lateral wall was measured for each cochlea by two independent reviewers, a neuroradiologist and an otolaryngologist. The interrater reliability was calculated using the intraclass correlation coefficient (ICC) and the Bland-Altman plot. Forty patients (19 males, 21 females) for a total of 80 cochleae were included. Interrater reliability on the same ear had a high level of agreement by both the ICC and the Bland-Altman plot. ICCs were 0.90 (95% CI: 0.82, 0.94) for the left ear and 0.96 (95% CI: 0.92, 0.98) for the right ear. Bland-Altman plot confirmed interrater reliability with all 96% of measurements falling within the 95% limits of agreement. Measurement between the round window and lateral cochlear wall can be consistently and reliably obtained from high-resolution temporal bone CT scans. Thus, it is feasible to utilize this method to estimate the cochlear length of patients undergoing cochlear implantation.

Perilymph pharmacokinetics of marker applied through a cochlear implant in guinea pigs

PubMed Central

Hartsock, Jared; Gill, Ruth; Smyth, Daniel; Kirk, Jonathon; Verhoeven, Kristien

2017-01-01

Patients undergoing cochlear implantation could benefit from a simultaneous application of drugs into the ear, helping preserve residual low-frequency hearing and afferent nerve fiber populations. One way to apply drugs is to incorporate a cannula into the implant, through which drug solution is driven. For such an approach, perilymph concentrations achieved and the distribution in the ear over time have not previously been documented. We used FITC-labeled dextran as a marker, delivering it into perilymph of guinea pigs at 10 or 100 nL/min though a cannula incorporated into a cochlear implant with the outlet in the mid basal turn. After injections of varying duration (2 hours, 1 day or 7 days) perilymph was collected from the cochlear apex using a sequential sampling technique, allowing dextran levels and gradients along scala tympani to be quantified. Data were interpreted quantitatively using computer simulations of the experiments. For injections of 2 hours duration, dextran levels were critically influenced by the presence or absence of fluid leakage at the cochleostomy site. When the cochleostomy was fluid-tight, substantially higher perilymph levels were achieved at the injection site, with concentration declining along scala tympani towards the apex. Contrary to expectations, large dextran gradients along scala tympani persisted after 24 hours of sustained injection and were still present in some animals after 7 days injection. Functional changes associated with implantation and dextran delivery, and the histological state of the implant and cannula were also documented. The persistent longitudinal gradients of dextan along the ear were not readily explained by computer simulations of the experiments based on prior pharmacokinetic data. One explanation is that inner ear pharmacokinetics are altered in the period after cochlear implantation, possibly by a permeabilization of the blood-labyrinth barrier as part of the immune response to the implant. PMID:28817653

Cochlear microphonic responses to acoustic clicks in guinea pig and their relation with microphonic responses to pure tones.

PubMed

Echeverría, E L; Robles, L W

1983-02-01

Cochlear microphonic (CM) responses to acoustic transient stimuli were studied at the three more basal turns of the cochlea in the guinea pig. The responses to rarefaction and condensation pressure pulses of less than 100-mus duration were recorded using the differential electrode technique. In some animals the CM response to pure tones was recorded at the same position at which the transient response was obtained. The transient responses recorded at the three turns of the cochlea displayed a damped oscillation at a frequency consistent with the values of cutoff frequency already known for the electrode positions. Some of the responses were significantly less damped than click responses previously reported. There was a good correlation between the cutoff frequency in the frequency response curve and the frequency of oscillation in the transient response for recordings obtained at the same position in the cochlea. A nonlinear effect was observed for changes in stimulus intensity. There was a less than proportional decrease in amplitude of the initial part of the damped oscillation for a decrease of the stimulus intensity, while the late part of the response behaved almost linearly. This nonlinearity observed in the CM transient response could not be explained by a nonlinear characteristic of the sort reported in the basilar membrane of the squirrel monkey by Robles et al. [J. Acoust. Soc. Am. 59, 926-939 (1976)]; rather it seems to be a saturation nonlinearity similar to the one known for sinusoidal stimulation.

Enzymes of acetylcholine metabolism in the rat cochlea.

PubMed

Godfrey, D A; Ross, C D

1985-01-01

The distributions within the rat cochlea of choline acetyltransferase and acetylcholinesterase activities were measured to evaluate the prominence of cholinergic mechanisms in cochlear function. Samples obtained by microdissection of freeze-dried bony labyrinths were assayed radiometrically. Activities of both enzymes were highest in regions containing olivocochlear fibers and terminals, especially the organ of Corti and spiral ganglion. Within the organ of Corti, activities of both enzymes were consistently higher in the vicinity of the inner hair cells than in that of the outer hair cells and were much lower in the apical turn than in middle or basal turns. Surgical cuts in the brain stem transecting the olivocochlear pathway on one side led within seven days to total loss of choline acetyltransferase activity in the ipsilateral organ of Corti. It is concluded that all cholinergic structures in the rat organ of Corti derive from the brain stem and that synapses on or near both inner and outer hair cells are cholinergic.

Electrically evoked compound action potentials are different depending on the site of cochlear stimulation.

PubMed

van de Heyning, Paul; Arauz, Santiago L; Atlas, Marcus; Baumgartner, Wolf-Dieter; Caversaccio, Marco; Chester-Browne, Ronel; Estienne, Patricia; Gavilan, Javier; Godey, Benoit; Gstöttner, Wolfgang; Han, Demin; Hagen, Rudolph; Kompis, Martin; Kuzovkov, Vlad; Lassaletta, Luis; Lefevre, Franc; Li, Yongxin; Müller, Joachim; Parnes, Lorne; Kleine Punte, Andrea; Raine, Christopher; Rajan, Gunesh; Rivas, Adriana; Rivas, José Antonio; Royle, Nicola; Sprinzl, Georg; Stephan, Kurt; Walkowiak, Adam; Yanov, Yuri; Zimmermann, Kim; Zorowka, Patrick; Skarzynski, Henryk

2016-11-01

One of the many parameters that can affect cochlear implant (CI) users' performance is the site of presentation of electrical stimulation, from the CI, to the auditory nerve. Evoked compound action potential (ECAP) measurements are commonly used to verify nerve function by stimulating one electrode contact in the cochlea and recording the resulting action potentials on the other contacts of the electrode array. The present study aimed to determine if the ECAP amplitude differs between the apical, middle, and basal region of the cochlea, if double peak potentials were more likely in the apex than the basal region of the cochlea, and if there were differences in the ECAP threshold and recovery function across the cochlea. ECAP measurements were performed in the apical, middle, and basal region of the cochlea at fixed sites of stimulation with varying recording electrodes. One hundred and forty one adult subjects with severe to profound sensorineural hearing loss fitted with a Standard or FLEX SOFT electrode were included in this study. ECAP responses were captured using MAESTRO System Software (MED-EL). The ECAP amplitude, threshold, and slope were determined using amplitude growth sequences. The 50% recovery rate was assessed using independent single sequences that have two stimulation pulses (a masker and a probe pulse) separated by a variable inter-pulse interval. For all recordings, ECAP peaks were annotated semi-automatically. ECAP amplitudes were greater upon stimulation of the apical region compared to the basal region of the cochlea. ECAP slopes were steeper in the apical region compared to the basal region of the cochlea and ECAP thresholds were lower in the middle region compared to the basal region of the cochlea. The incidence of double peaks was greater upon stimulation of the apical region compared to the basal region of the cochlea. This data indicates that the site and intensity of cochlear stimulation affect ECAP properties.

Cytotoxic effects of dimethyl sulphoxide (DMSO) on cochlear organotypic cultures

PubMed Central

Qi, Weidong; Ding, Dalian; Salvi*, Richard J.

2008-01-01

The amphipathic molecule dimethyl sulphoxide (DMSO) is a solvent often used to dissolve compounds applied to the inner ear; however, little is known about its potential cytotoxic side effects. To address this question, we applied 0.1 to 6% DMSO for 24 h to cochlear organotypic cultures from postnatal day 3 rats and examined its cytotoxic effects. DMSO concentrations of 0.1% and 0.25% caused little or no damage. However, concentrations between 0.5 and 6% resulted in stereocilia damage, hair cell swelling and a dose-dependent loss of hair cells. Hair cell damage began in the basal turn of the cochlea and spread towards the apex with increasing concentration. Surprisingly, DMSO-induced damage was greater for inner hair cells than outer hair cell whereas nearby supporting cells were largely unaffected. Most hair cell death was associated with nuclear shrinkage and fragmentation, morphological features consistent with apoptosis. DMSO treatment induced TUNEL positive staining in many hair cells and activated both initiator caspase-9 and caspase-8 and executioner caspase-3; this suggests that apoptosis is initiated by both intrinsic mitochondrial and extrinsic membrane cell death signaling pathways. PMID:18207679

Round-window delivery of neurotrophin 3 regenerates cochlear synapses after acoustic overexposure.

PubMed

Suzuki, Jun; Corfas, Gabriel; Liberman, M Charles

2016-04-25

In acquired sensorineural hearing loss, such as that produced by noise or aging, there can be massive loss of the synaptic connections between cochlear sensory cells and primary sensory neurons, without loss of the sensory cells themselves. Because the cell bodies and central projections of these cochlear neurons survive for months to years, there is a long therapeutic window in which to re-establish functional connections and improve hearing ability. Here we show in noise-exposed mice that local delivery of neurotrophin-3 (NT-3) to the round window niche, 24 hours after an exposure that causes an immediate loss of up to 50% loss of synapses in the cochlear basal region, can regenerate pre- and post-synaptic elements at the hair cell / cochlear nerve interface. This synaptic regeneration, as documented by confocal microscopy of immunostained cochlear sensory epithelia, was coupled with a corresponding functional recovery, as seen in the suprathreshold amplitude of auditory brainstem response Wave 1. Cochlear delivery of neurotrophins in humans is likely achievable as an office procedure via transtympanic injection, making our results highly significant in a translational context.

[Topographic anatomy of the hook region and its significance for the choice of the surgical technique for the cochlear implantation].

PubMed

Yanov, Yu K; Kuzovkov, V E; Lilenko, A S; Kostevich, I V; Sugarova, S B; Amonov, A Sh

The mode of the introduction of the active electrode of a cochlear implant into the cochlea remains a key issue as far as cochlear implantation is concerned. Especially much attention has recently been given to the relationship between the anatomical features of the basal region of the cochlea (the so-called 'fish hook') and the possibility to approach it. We have undertaken the attempt to optimize the approach to the tympanic canal (scala tympanica) of the cochlea with a view to reducing to a minimum the risk of an injury to the cochlear structures in the course of cochlear implantation. A total of 35 cadaveric temporal bones were examined to measure the fine structures of the hook region and evaluate the risk of their damages associated with various approaches to the tympanic canal.

Longitudinal flow of endolymph measured by distribution of tetraethylammonium and choline in scala media.

PubMed

Syková, E; Syka, J; Johnstone, B M; Yates, G K

1987-01-01

Longitudinal endolymph flow rate in the guinea pig cochlea was measured by determining the rate of migration of extrinsic ions, tetraethylammonium chloride (TEA) or choline, with a potassium sensitive ion-selective microelectrode (ISM). Low concentrations of iontophoretically injected TEA were detected with the ISM at various distances from the injection electrode. The results were variable when the ISM was used to record spread of TEA from turn II to turn I and vice versa. However, consistent data were obtained when the TEA spread was measured at different electrode separations (0.2, 0.5, 0.7 mm) within turn II. Electrode locations were systematically exchanged without changing their distance, i.e. the ISM electrode was placed basally or apically with respect to the TEA electrode. Comparison of data with a model, which combines the bulk diffusion of TEA and the flow of endolymph, is consistent with a rate of endolymph flow in turn II of about 0.2 mm/min, apex to base. A similar value was also obtained with the iontophoretic injection of choline. The endolymph flow rate may be different in turn I as indicated by measurements of compound action potential (CAP) changes. However, the results of experiments when TEA spread is measured at large distances must be interpreted cautiously because TEA may enter cellular walls of the cochlear duct and alternative routes of transport may be involved.

The inner ear of Diacodexis, the oldest artiodactyl mammal

PubMed Central

Orliac, M J; Benoit, J; O'Leary, M A

2012-01-01

We provide the first detailed description of the inner ear of the oldest artiodactyl, Diacodexis, based on a three-dimensional reconstruction extracted from computed tomography imagery of a skull of Diacodexis ilicis of earliest Wasatchian age (ca. 55 Ma). This description provides new anatomical data for the earliest artiodactyls, and reveals that the bony labyrinth of Diacodexis differs greatly from that of modern artiodactyls described so far. The bony labyrinth of Diacodexis presents a weakly coiled cochlea (720 °), a secondary common crus, a dorsal extension of the anterior semicircular canal more pronounced than that of the posterior one, and a small angle between the basal turn of the bony cochlear canal and the lateral semicircular canal. This suite of characters also occurs in basal eutherian mammals. Diacodexis strongly resembles small living tragulid ruminants in its overall body shape and hindlimb proportions. Comparison of the bony labyrinth of Diacodexis to that of the tragulid Moschiola meminna (Indian mouse deer) reveals great morphological difference in cochlear shape and semicircular canal disposition. The shape of the cochlea suggests that Diacodexis was a high-frequency hearing specialist, with a high low-frequency hearing limit (543 Hz at 60 dB). By comparison, the estimated low-frequency limit of Moschiola meminna is much lower (186.0 Hz at 60 dB). We also assess the locomotor agility of Diacodexis based on measurements of the semicircular canals. Locomotor agility estimates for Diacodexis range between 3.62 and 3.93, and suggest a degree of agility compatible with a nimble, fast running to jumping animal. These results are congruent with the postcranial functional analysis for this extinct taxon. PMID:22938073

Damage to cochlear efferents following AF64A intoxication.

PubMed

Smith, D W; Mount, R J

1993-07-01

Damage to cochlear efferents in chinchillas was assessed using transmission electron microscopy following unilateral treatment with the cholinotoxin ethylcholine mustard aziridinium ion (AF64A). AF64A was diluted in artificial perilymph to concentrations ranging from 0.5 to 100 microM. Survival times ranged from 1 to 12 weeks. At concentrations above 10 microM, widespread damage was noted to efferent fibers within the inner spiral bundle (ISB), tunnel spiral bundle (TSB), tunnel radial fibers (TRF) and efferent terminals at the base of OHCs. This damage included degeneration of fibers and terminals, delamination of mitochondria, vacuolization, and loss of cell membrane. However, at high concentrations, non-specific damage was also noted as thinnings or discontinuities of the membrane of OHCs and afferent fibers. At concentrations between 3 and 10 microM, selective damage was observed to efferent fibers within the ISB, TSB, TRF, and to terminals at the base of the OHCs, with all other structures appearing normal. At concentrations of 0.5 and 1 microM, damage was limited to efferent fibers within the TSB and ISB below the inner hair cells. In general, insult was greatest to middle- and basal-turn efferents, and longer survival times did not produce greater damage to, or loss of, efferents. These data suggest that at low concentrations, AF64A produces a partial yet selective degeneration of cochlear efferents within both the medial and lateral tracts, and that at the lowest concentrations used in these studies, AF64A produces a preferential insult on lateral olivocochlear efferents.

Dexamethasone concentration gradients along scala tympani after application to the round window membrane.

PubMed

Plontke, Stefan K; Biegner, Thorsten; Kammerer, Bernd; Delabar, Ursular; Salt, Alec N

2008-04-01

Local application of dexamethasone-21-dihydrogen-phosphate (Dex-P) to the round window (RW) membrane of guinea pigs produces a substantial basal-apical concentration gradient in scala tympani (ST) perilymph. In recent years, intratympanically applied glucocorticoids are increasingly being used for the treatment of inner ear disease. Although measurements of intracochlear concentrations after RW application exist, there is limited information on the distribution of these drugs in the inner ear fluids. It has been predicted from computer simulations that substantial concentration gradients will occur after RW application, with lower concentrations expected in apical turns. Concentration gradients of other substances along the cochlea have recently been confirmed using a sequential apical sampling method to obtain perilymph. Dexamethasone-21-dihydrogen-phosphate (10 mg/ml) was administered to the RW membrane of guinea pigs (n = 9) in vivo for 2 to 3 hours. Perilymph was then collected using a protocol in which 10 samples, each of approximately 1 mul, were taken sequentially from the cochlear apex into capillary tubes. Dexamethasone-21-dihydrogen-phosphate concentration of the samples was analyzed by high-performance liquid chromatography. Interpretation of sample data using a finite element model allowed the longitudinal gradients of Dex-P in ST to be quantified. The Dex-P content of the first sample in each experiment (dominated by perilymph from apical regions) was substantially lower than that of the third and fourth sample (dominated by basal turn perilymph). These findings qualitatively demonstrated the existence of a concentration gradient along ST. After detailed analysis of the measured sample concentrations using an established finite element computer model, the mean basal-apical concentration gradient was estimated to be 17,000. Both absolute concentrations of Dex-P in ST and the basal-apical gradients were found to vary substantially. The existence of substantial basal-apical concentration gradients of Dex-P in ST perilymph were demonstrated experimentally. If the variability in peak concentration and gradient is also present under clinical conditions, this may contribute to the heterogeneity of outcome that is observed after intratympanic application of glucocorticoids for various inner ear diseases.

Dexamethasone concentration gradients along scala tympani after application to the round window membrane

PubMed Central

Salt, Alec N

2008-01-01

Hypothesis Local application of dexamethasone-21-dihydrogene-phosphate (Dex-P) to the round window membrane (RWM) of guinea pigs produces a substantial basal-apical concentration gradient in scala tympani (ST) perilymph. Background In recent years, intratympanically-applied glucocorticoids are increasingly being used for the treatment of inner ear disease. Although measurements of intracochlear concentrations after round window (RW) application exist, there is limited information on the distribution of these drugs in the inner ear fluids. It has been predicted from computer simulations that substantial concentration gradients will occur with lower concentrations expected in apical turns after RW application. Concentration gradients of other substances along the cochlea have recently been confirmed using a sequential apical sampling method to obtain perilymph. Methods Dex-P (10mg/ml) was administered to the RWM of guinea pigs (n=9) in vivo for 2 to 3 hours. Perilymph was then collected using a protocol in which ten samples, each of approximately 1μl, were taken sequentially from the cochlear apex into capillary tubes. Dex-P concentration of the samples was determined by HPLC. Interpretation of sample data using a finite element model allowed the longitudinal gradients of Dex-P in scala tympani to be quantified. Results The Dex-P content of the first sample in each experiment (dominated by perilymph from apical regions) was substantially lower than that of the third and fourth sample (dominated by basal turn perilymph). These findings qualitatively demonstrated the existence of a concentration gradient along scala tympani (ST). After detailed analysis of the measured sample concentrations using an established finite element computer model, the mean basal-apical concentration gradient was estimated to be 17•103. Both absolute concentrations of Dex-P in ST and the basal-apical gradients were found to vary substantially. Conclusion The existence of substantial basal-apical concentration gradients of Dex-P in ST perilymph was demonstrated experimentally. If the variability in peak concentration and gradient is also present under clinical conditions this may contribute to the heterogeneity of outcome that is observed after intratympanic application of glucocorticoids for various inner ear diseases. PMID:18277312

Response of cochlear blood flow to prostaglandin E1 applied topically to the round window.

PubMed

Tominaga, Mitsuo; Yamamoto, Hiroshi; Sone, Michihiko; Teranishi, Masa-aki; Nakashima, Tsutomu

2006-03-01

The increase in cochlear blood flow (CBF) after administration of prostaglandin E1 (PGE1) to the round window depends on increased blood flow through the anterior inferior cerebellar artery (AICA). To evaluate the response of CBF to PGE1 applied topically to the round window, and to investigate the origin of blood flow changes after this topical application. The response of CBF to topically applied PGE1 was measured by placing the tip of a laser Doppler probe on the bony wall of the basal turn of the cochlea after the middle ear mucosa over the cochlea had been removed in guinea pigs and rats. In rats, the CBF response to PGE1 administration was investigated after occlusion of the AICA or stapedial artery. CBF increased following PGE1 administration in both guinea pigs and rats. In rats, CBF increased from 100% to 132%+/-10% (mean+/-SD) after the topical application of 0.5 microl of a 0.014% PGE1 solution. CBF decreased after occlusion of the AICA or stapedial artery but did not increase after PGE1 administration during occlusion of the AICA. The CBF response to PGE1 administration was similar before and after occlusion of the stapedial artery.

Acute hyperfibrinogenemia impairs cochlear blood flow and hearing function in guinea pigs in vivo.

PubMed

Ihler, Fritz; Strieth, Sebastian; Pieri, Nicos; Göhring, Peter; Canis, Martin

2012-03-01

Impairment of microcirculation is a possible cause of sudden sensorineural hearing loss (SSNHL). Fibrinogen is known as a risk factor for both microvascular dysfunction and SSNHL. Therefore, the aim of this study was to investigate the effect of elevated serum levels of fibrinogen on cochlear blood flow and hearing function in vivo. One group of guinea pigs received two consecutive injections of 100 mg fibrinogen while a control group received equimolar doses of albumin. Measurements of cochlear microcirculation by intravital microscopy and of hearing thresholds by auditory brainstem response (ABR) recordings were carried out before, after first and after second injection. Ten healthy guinea pigs were randomly assigned to a treatment group or a control group of five animals each. Serum fibrinogen levels were elevated after the first and second injections of fibrinogen compared to basal values and control group respectively. Increasing levels of fibrinogen were paralleled by decreasing cochlear blood flow as well as increasing hearing thresholds. Hearing threshold correlated negatively with cochlear blood flow. The effect of microcirculatory impairment on hearing function could be explained by a malfunction of the cochlear amplifier. Further investigation is needed to quantify cochlear potentials under elevated serum fibrinogen levels.

Robot-assisted three-dimensional registration for cochlear implant surgery using a common-path swept-source optical coherence tomography probe

NASA Astrophysics Data System (ADS)

Gurbani, Saumya S.; Wilkening, Paul; Zhao, Mingtao; Gonenc, Berk; Cheon, Gyeong Woo; Iordachita, Iulian I.; Chien, Wade; Taylor, Russell H.; Niparko, John K.; Kang, Jin U.

2014-05-01

Cochlear implantation offers the potential to restore sensitive hearing in patients with severe to profound deafness. However, surgical placement of the electrode array within the cochlea can produce trauma to sensorineural components, particularly if the initial turn of the cochlea is not successfully navigated as the array is advanced. In this work, we present a robot-mounted common-path swept-source optical coherence tomography endoscopic platform for three-dimensional (3-D) optical coherence tomography (OCT) registration and preoperative surgical planning for cochlear implant surgery. The platform is composed of a common-path 600-μm diameter fiber optic rotary probe attached to a five degrees of freedom robot capable of 1 μm precision movement. The system is tested on a dry fixed ex vivo human temporal bone, and we demonstrate the feasibility of a 3-D OCT registration of the cochlea to accurately describe the spatial and angular profiles of the canal formed by the scala tympani into the first cochlear turn.

The influence of cochlear shape on low-frequency hearing.

PubMed

Manoussaki, Daphne; Chadwick, Richard S; Ketten, Darlene R; Arruda, Julie; Dimitriadis, Emilios K; O'Malley, Jen T

2008-04-22

The conventional theory about the snail shell shape of the mammalian cochlea is that it evolved essentially and perhaps solely to conserve space inside the skull. Recently, a theory proposed that the spiral's graded curvature enhances the cochlea's mechanical response to low frequencies. This article provides a multispecies analysis of cochlear shape to test this theory and demonstrates that the ratio of the radii of curvature from the outermost and innermost turns of the cochlear spiral is a significant cochlear feature that correlates strongly with low-frequency hearing limits. The ratio, which is a measure of curvature gradient, is a reflection of the ability of cochlear curvature to focus acoustic energy at the outer wall of the cochlear canal as the wave propagates toward the apex of the cochlea.

[Applied anatomy of scala tympani inlet related to cochlear implantation].

PubMed

Zou, Tuanming; Guo, Menghe; Zhang, Hongzheng; Shu, Fan; Xie, Nanping

2012-06-01

To investigate the related parameters of the temporal bone structure for determining the position of implanting electrode into the scala tympani in cochlear implantation surgery through the facial recess and epitympanum approach. In a surgical simulation experiment, 20 human temporal bones were studied and measured to determine the related parameters of the temporal bone structure. The distance 5.91∓0.29 mm between the short process of the incus and the round window niche, 2.11∓0.18 mm between the stapes and the round window niche, 6.70∓0.19 mm between the facial nerve in the perpendicular paragraph and the round window niche, 2.22∓0.21 mm from the pyramidal eminence to the round window, and 2.16∓0.14 mm between the stapes and the round window. The minimal distance between the implanting electrode and the vestibular window was 2.12∓0.19 mm. The distance between the cochleariform process and the round window niche was 3.79∓0.17 mm. The position of the cochlear electrode array insertion into the second cochlear turn was 2.25∓0.13 mm under the stapes. The location of the cochlear electrode array insertion into the second cochlear turn was 2.28∓0.20 mm inferior to the pyramidal eminence. These parameters provide a reference value to determine the different positions of cochlear electrode array insertion into the scale tympani in different patients.

Characteristics and pathogenesis of facial nerve stimulation after cochlear implant surgeries: A single-center retrospective analysis from 1,151 patients.

PubMed

Kim, Y R; Yoo, M H; Lee, J Y; Yang, C J; Park, J W; Kang, B C; Kang, W S; Ahn, J H; Chung, J W; Park, H J

2018-05-29

Incidence of facial nerve stimulation (FNS) was 2.8% (32 out of 1151) and higher in ears with cochlear anomaly (6.4%, 25 out of 391) than without cochlear anomaly (0.9%, 7 out of 760). FNS occurred at various current levels and locations of electrodes by different mechanisms related to incomplete insertion of electrodes, cochleo-facial dehiscence, and types of cochlear anomalies. FNS at apical electrodes related to cochleo-facial dehiscence with low current levels, and FNS at basal electrodes with high current levels and partial insertion of electrodes. FNS at most electrodes with high current levels was the most common type in patients with a common cavity or narrowing of the bony cochlear nerve canal. Understanding the mechanisms of FNS might provide insight for preventing FNS when performing CI surgeries. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Prevalence of Extracochlear Electrodes: Computerized Tomography Scans, Cochlear Implant Maps, and Operative Reports.

PubMed

Holder, Jourdan T; Kessler, David M; Noble, Jack H; Gifford, René H; Labadie, Robert F

2018-06-01

To quantify and compare the number of cochlear implant (CI) electrodes found to be extracochlear on postoperative computerized tomography (CT) scans, the number of basal electrodes deactivated during standard CI mapping (without knowledge of the postoperative CT scan), and the extent of electrode insertion noted by the surgeon. Retrospective. Academic Medical Center. Two hundred sixty-two patients underwent standard cochlear implantation and postoperative temporal bone CT scanning. Scans were analyzed to determine the number of extracochlear electrodes. Standard CI programming had been completed without knowledge of the extracochlear electrodes identified on the CT. These standard CI maps were reviewed to record the number of deactivated basal electrodes. Lastly, each operative report was reviewed to record the extent of reported electrode insertion. 13.4% (n = 35) of CIs were found to have at least one electrode outside of the cochlea on the CT scan. Review of CI mapping indicated that audiologists had deactivated extracochlear electrodes in 60% (21) of these cases. Review of operative reports revealed that surgeons correctly indicated the number of extracochlear electrodes in 6% (2) of these cases. Extracochlear electrodes were correctly identified audiologically in 60% of cases and in surgical reports in 6% of cases; however, it is possible that at least a portion of these cases involved postoperative electrode migration. Given these findings, postoperative CT scans can provide information regarding basal electrode location, which could help improve programming accuracy, associated frequency allocation, and audibility with appropriate deactivation of extracochlear electrodes.

Noise-induced cochlear synaptopathy in rhesus monkeys (Macaca mulatta).

PubMed

Valero, M D; Burton, J A; Hauser, S N; Hackett, T A; Ramachandran, R; Liberman, M C

2017-09-01

Cochlear synaptopathy can result from various insults, including acoustic trauma, aging, ototoxicity, or chronic conductive hearing loss. For example, moderate noise exposure in mice can destroy up to ∼50% of synapses between auditory nerve fibers (ANFs) and inner hair cells (IHCs) without affecting outer hair cells (OHCs) or thresholds, because the synaptopathy occurs first in high-threshold ANFs. However, the fiber loss likely impairs temporal processing and hearing-in-noise, a classic complaint of those with sensorineural hearing loss. Non-human primates appear to be less vulnerable to noise-induced hair-cell loss than rodents, but their susceptibility to synaptopathy has not been studied. Because establishing a non-human primate model may be important in the development of diagnostics and therapeutics, we examined cochlear innervation and the damaging effects of acoustic overexposure in young adult rhesus macaques. Anesthetized animals were exposed bilaterally to narrow-band noise centered at 2 kHz at various sound-pressure levels for 4 h. Cochlear function was assayed for up to 8 weeks following exposure via auditory brainstem responses (ABRs) and otoacoustic emissions (OAEs). A moderate loss of synaptic connections (mean of 12-27% in the basal half of the cochlea) followed temporary threshold shifts (TTS), despite minimal hair-cell loss. A dramatic loss of synapses (mean of 50-75% in the basal half of the cochlea) was seen on IHCs surviving noise exposures that produced permanent threshold shifts (PTS) and widespread hair-cell loss. Higher noise levels were required to produce PTS in macaques compared to rodents, suggesting that primates are less vulnerable to hair-cell loss. However, the phenomenon of noise-induced cochlear synaptopathy in primates is similar to that seen in rodents. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of systemic lipoic acid on hearing preservation after cochlear implantation via the round window approach: A guinea pig model.

PubMed

Chang, Mun Young; Gwon, Tae Mok; Lee, Ho Sun; Lee, Jun Ho; Oh, Seung Ha; Kim, Sung June; Park, Min-Hyun

2017-03-15

The present study aimed to evaluate the effects of systemic lipoic acid on hearing preservation after cochlear implantation. Twelve Dunkin-Hartley guinea pigs were randomly divided into two groups: the control group and the lipoic acid group. Animals in the lipoic acid group received lipoic acid intraperitoneally for 4 weeks. A sterilised silicone electrode-dummy was inserted through the round window to a depth of approximately 5 mm. The hearing level was measured using auditory brainstem responses (ABRs) prior to electrode-dummy insertion, and at 4 days and 1, 2, 3 and 4 weeks after electrode-dummy insertion. The threshold shift was defined as the difference between the pre-operative threshold and each of the post-operative thresholds. The cochleae were examined histologically 4 weeks after electrode-dummy insertion. Threshold shifts changed with frequency but not time. At 2kHz, ABR threshold shifts were statistically significantly lower in the lipoic acid group than the control group. At 8, 16 and 32kHz, there was no significant difference in the ABR threshold shift between the two groups. Histologic review revealed less intracochlear fibrosis along the electrode-dummy insertion site in the lipoic acid group than in the control group. The spiral ganglion cell densities of the basal, middle and apical turns were significantly higher in the lipoic acid group compared with the control group. Therefore, systemic lipoic acid administration appears to effectively preserve hearing at low frequencies in patients undergoing cochlear implantation. These effects may be attributed to the protection of spiral ganglion cells and prevention of intracochlear fibrosis. Copyright © 2017 Elsevier B.V. All rights reserved.

How do the medial olivocochlear efferents influence the biomechanics of the outer hair cells and thereby the cochlear amplifier? Simulation results

NASA Astrophysics Data System (ADS)

Saremi, Amin; Stenfelt, Stefan; Verhulst, Sarah

2015-12-01

The bottom-up signal pathway, which starts from the outer ear and leads to the brain cortices, gives the classic image of the human sound perception. However, there have been growing evidences in the last six decades for existence of a functional descending network whereby the central auditory system can modulate the early auditory processing, in a top-down manner. The medial olivocochlear efferent fibers project from the superior olivary complex at the brainstem into the inner ear. They are linked to the basal poles of the hair cells by forming synaptic cisterns. This descending network can activate nicotinic cholinergic receptors (nAChR) that increase the membrane conductance of the outer hair cells and thereby modify the magnitude of the active force generated inside the cochlea. The aim of the presented work is to quantitatively investigate how the changes in the biomechanics of the outer hair cells, caused by the efferent activation, manipulate the cochlear responses. This is done by means of a frequency-domain biophysical model of the cochlea [12] where the parameters of the model convey physiological interpretations of the human cochlear structures. The simulations manifest that a doubling of the outer hair cell conductance, due to efferent activation, leads to a frequency-dependent gain reduction along the cochlear duct with its highest effect at frequencies between 1 kHz and 3.5 kHz and a maximum of approximately 10 dB gain reduction at 2 kHz. This amount of the gain inhibition and its frequency dependence reasonably agrees with the experimental data recorded from guinea pig, cat and human cochleae where the medial olivococlear efferents had been elicited by broad-band stimuli. The simulations also indicate that the efferent-induced increase of the outer hair cell conductance increases the best frequency of the cochlear responses, in the basal region. The presented simulations quantitatively confirm that activation of the medial olivocochlear efferents can biomechanically manipulate the cochlear responses, in a top-down manner, by inhibiting the gain of the cochlear amplifier as well as altering the frequency-position map (tuning pattern) of the cochlea.

Evaluating cochlear implant trauma to the scala vestibuli.

PubMed

Adunka, O; Kiefer, J; Unkelbach, M H; Radeloff, A; Gstoettner, W

2005-04-01

Placement of cochlear implant electrodes into the scala vestibuli may be intentional, e.g. in case of blocked scala tympani or unintentional as a result of trauma to the basilar membrane or erroneous location of the cochieostomy. The aim of this study was to evaluate the morphological consequences and cochlear trauma after implantation of different cochlear implant electrode arrays in the scala vestibuli. Human temporal bone study with histological and radiological evaluation. Twelve human cadaver temporal bones were implanted with different cochlear implant electrodes. Implanted bones were processed using a special method to section undecalcified bone. Cochlear trauma and intracochlear positions. All implanted electrodes were implanted into the scala vestibuli using a special approach that allows direct scala vestibuli insertions. Fractures of the osseous spiral lamina were evaluated in some bones in the basal cochlear regions. In most electrodes, delicate structures of the organ of Corti were left intact, however, Reissner's membrane was destroyed in all specimens and the electrode lay upon the tectorial membrane. In some bones the organ of Corti was destroyed. Scala vestibuli insertions did not cause severe trauma to osseous or neural structures, thus preserving the basis for electrostimulation of the cochlea. However, destruction of Reissner's membrane and impact on the Organ of Corti can be assumed to destroy residual hearing.

Choline acetyltransferase, glutamate decarboxylase and tyrosine hydroxylase in the cochlea and cochlear nucleus of the guinea pig.

PubMed

Fex, J; Wenthold, R J

1976-06-18

Activities of choline acetyltransferase (ChAC), glutamate decarboxylase (GAD) and tyrosine hydroxylase (TH), enzymes catalyzing the synthesis of acetylcholine (ACh), gamma-aminobutyric acid (GABA) and catecholamines, respectively, were measured in the cochlea and cochlear nucleus of the guinea pig. ChAc activity in the organ of Corti, third turn, was 1270 pmole ACh formed/min/mg protein (ChAc, 1270) and was higher than in turn 4 (ChAc, 543). ChAc activity was higher when the preparation included the inner hair cell region than when not. GAD activity in samples of turn 3 and 4 combined was low, 0.17 nmole GABA formed/min/mg protein (GAD, 0.17). All 3 enzymes were low in auditory nerve: ChAc, 1.7, GAD, 0.10 and TH, 1.0 pmole DOPA formed/min/mg protein. In the cochlear nucleus, the values were: ChAc, 129, GAD, 1.70 and TH, 2.7. The findings on the distribution of ChAc activity in the organ of Corti fit the hypothesis that the olivocochlear nerve fibers are cholinergic. Because of low GAD in the cochlea, GABA is unlikely to be transmitter in the organ of Corti. Similarly, it is unlikely that ACh, GABA or a catecholamine is a transmitter between the auditory nerve and the cochlear nucleus.

Resistance of Gerbil Auditory Function to Reversible Decrease in Cochlear Blood Flow.

PubMed

El Afia, Fahd; Giraudet, Fabrice; Gilain, Laurent; Mom, Thierry; Avan, Paul

2017-01-01

The objective was to design in gerbils a model of reversible decrease in cochlear blood flow (CBF) and analyze its influence on cochlear function. In Mongolian gerbils injected with ferromagnetic microbeads, a magnet placed near the porus acusticus allowed CBF to be manipulated. The cochlear microphonic potential (CM) from the basal cochlea was monitored by a round-window electrode. In 13 of the 20 successfully injected gerbils, stable CBF reduction was obtained for 11.5 min on average. The CM was affected only when CBF fell to less than 60% of its baseline, yet remained >40% of its initial level in about 2/3 of such cases. After CBF restoration, CM recovery was fast and usually complete. Reduced CM came with a 35- to 45-dB threshold elevation of neural responses determined by compound action potentials. This method allowing reversible changes of CBF confirms the robustness of cochlear function to decreased CBF. It can be used to study whether a hypovascularized cochlea is abnormally sensitive to stress. © 2017 S. Karger AG, Basel.

Effect of infrasound on cochlear damage from exposure to a 4 kHz octave band of noise.

PubMed

Harding, Gary W; Bohne, Barbara A; Lee, Steve C; Salt, Alec N

2007-03-01

Infrasound (i.e., <20 Hz for humans; <100 Hz for chinchillas) is not audible, but exposure to high-levels of infrasound will produce large movements of cochlear fluids. We speculated that high-level infrasound might bias the basilar membrane and perhaps be able to minimize noise-induced hearing loss. Chinchillas were simultaneously exposed to a 30 Hz tone at 100 dB SPL and a 4 kHz OBN at either 108 dB SPL for 1.75 h or 86 dB SPL for 24h. For each animal, the tympanic membrane (TM) in one ear was perforated ( approximately 1 mm(2)) prior to exposure to attenuate infrasound transmission to that cochlea by about 50 dB SPL. Controls included animals that were exposed to the infrasound only or the 4 kHz OBN only. ABR threshold shifts (TSs) and DPOAE level shifts (LSs) were determined pre- and post-TM-perforation and immediately post-exposure, just before cochlear fixation. The cochleae were dehydrated, embedded in plastic, and dissected into flat preparations of the organ of Corti (OC). Each dissected segment was evaluated for losses of inner hair cells (IHCs) and outer hair cells (OHCs). For each chinchilla, the magnitude and pattern of functional and hair cell losses were compared between their right and left cochleae. The TM perforation produced no ABR TS across frequency but did produce a 10-21 dB DPOAE LS from 0.6 to 2 kHz. The infrasound exposure alone resulted in a 10-20 dB ABR TS at and below 2 kHz, no DPOAE LS and no IHC or OHC losses. Exposure to the 4 kHz OBN alone at 108 dB produced a 10-50 dB ABR TS for 0.5-12 kHz, a 10-60 dB DPOAE LS for 0.6-16 kHz and severe OHC loss in the middle of the first turn. When infrasound was present during exposure to the 4 kHz OBN at 108 dB, the functional losses and OHC losses extended much further toward the apical and basal tips of the OC than in cochleae exposed to the 4 kHz OBN alone. Exposure to only the 4 kHz OBN at 86 dB produces a 10-40 dB ABR TS for 3-12 kHz and 10-30 dB DPOAE LS for 3-8 kHz but little or no OHC loss in the middle of the first turn. No differences were found in the functional and hair-cell losses from exposure to the 4 kHz OBN at 86 dB in the presence or absence of infrasound. We hypothesize that exposure to infrasound and an intense 4 kHz OBN increases cochlear damage because the large fluid movements from infrasound cause more intermixing of cochlear fluids through the damaged reticular lamina. Simultaneous infrasound and a moderate 4 kHz OBN did not increase cochlear damage because the reticular lamina rarely breaks down during this moderate level exposure.

Effect of infrasound on cochlear damage from exposure to a 4-kHz octave band of noise

PubMed Central

Harding, Gary W.; Bohne, Barbara A.; Lee, Steve C.; Salt, Alec N.

2008-01-01

Infrasound (i.e., < 20 Hz for humans; < 100 Hz for chinchillas) is not audible, but exposure to high levels of infrasound will produce large movements of cochlear fluids. We speculated that high-level infrasound might bias the basilar membrane and perhaps be able to minimize noise-induced hearing loss. Chinchillas were simultaneously exposed to a 30 Hz tone at 100 dB SPL and a 4-kHz OBN at either 108 dB SPL for 1.75 h or 86 dB SPL for 24 h. For each animal, the tympanic membrane (TM) in one ear was perforated (~1 mm2) prior to exposure to attenuate infrasound transmission to that cochlea by about 50 dB SPL. Controls included animals that were exposed to the infrasound only or the 4-kHz OBN only. ABR threshold shifts (TSs) and DPOAE level shifts (LSs) were determined pre- and post-TM-perforation and immediately post-exposure, just before cochlear fixation. The cochleae were dehydrated, embedded in plastic, and dissected into flat preparations of the organ of Corti (OC). Each dissected segment was evaluated for losses of inner hair cells (IHCs) and outer hair cells (OHCs). For each chinchilla, the magnitude and pattern of functional and hair cell losses were compared between their right and left cochleae. The TM perforation produced no ABR TS across frequency but did produce a 10–21 dB DPOAE LS from 0.6–2 kHz. The infrasound exposure alone resulted in a 10–20 dB ABR TS at and below 2 kHz, no DPOAE LS and no IHC or OHC losses. Exposure to the 4-kHz OBN alone at 108 dB produced a 10–50 dB ABR TS for 0.5–12 kHz, a 10–60 dB DPOAE LS for 0.6–16 kHz and severe OHC loss in the middle of the first turn. When infrasound was present during exposure to the 4-kHz OBN at 108 dB, the functional losses and OHC losses extended much further toward the apical and basal tips of the OC than in cochleae exposed to the 4-kHz OBN alone. Exposure to only the 4-kHz OBN at 86 dB produces a 10–40 dB ABR TS for 3–12 kHz and 10–30 dB DPOAE LS for 3–8 kHz but little or no OHC loss in the middle of the first turn. No differences were found in the functional and hair-cell losses from exposure to the 4-kHz OBN at 86 dB in the presence or absence of infrasound. We hypothesize that exposure to infrasound and an intense 4-kHz OBN increases cochlear damage because the large fluid movements from infrasound cause more intermixing of cochlear fluids through the damaged reticular lamina. Simultaneous infrasound and a moderate 4-kHz OBN did not increase cochlear damage because the reticular lamina rarely breaks down during this moderate level exposure. PMID:17300889

The cochlea in skull base surgery: an anatomy study.

PubMed

Wang, Jian; Yoshioka, Fumitaka; Joo, Wonil; Komune, Noritaka; Quilis-Quesada, Vicent; Rhoton, Albert L

2016-11-01

OBJECTIVE The object of this study was to examine the relationships of the cochlea as a guide for avoiding both cochlear damage with loss of hearing in middle fossa approaches and injury to adjacent structures in approaches directed through the cochlea. METHODS Twenty adult cadaveric middle fossae were examined using magnifications of ×3 to ×40. RESULTS The cochlea sits below the floor of the middle fossa in the area between and below the labyrinthine segment of the facial nerve and greater petrosal nerve (GPN) and adjacent to the lateral genu of the petrous carotid. Approximately one-third of the cochlea extends below the medial edge of the labyrinthine segment of the facial nerve, geniculate ganglion, and proximal part of the GPN. The medial part of the basal and middle turns are the parts at greatest risk in drilling the floor of the middle fossa to expose the nerves in middle fossa approaches to the internal acoustic meatus and in anterior petrosectomy approaches. Resection of the cochlea is used selectively in extending approaches through the mastoid toward the lateral edge of the clivus and front of the brainstem. CONCLUSIONS An understanding of the location and relationships of the cochlea will reduce the likelihood of cochlear damage with hearing loss in approaches directed through the middle fossa and reduce the incidence of injury to adjacent structures in approaches directed through the cochlea.

Steroid intracochlear distribution differs by administration method: Systemic versus intratympanic injection.

PubMed

Lee, Jong Joo; Jang, Jeong Hun; Choo, Oak-Sung; Lim, Hye Jin; Choung, Yun-Hoon

2018-01-01

Steroids have been widely used to treat inner-ear diseases such as sudden sensorineural hearing loss, tinnitus, and Meniere's disease. They can be given via either systemic or intratympanic (IT) injection. The purpose of the present study was to explore differences in intracochlear steroid distribution by the administration method employed (systemic vs. IT injection). Animal study. Twenty-three Sprague-Dawley rats were given fluorescein isothiocyanate-labeled dexamethasone (FITC-DEX) three times (on successive days) via intraperitoneal (IP) or IT injection. Cochlear uptake of FITC-DEX was evaluated via immunohistochemistry and flow cytometry at 6 hours, and 3 and 7 days after the final injection. FITC-DEX uptake was evident in spiral ganglion cells (SGs), the organ of Corti (OC), and the lateral walls (LWs), the basal turns of which were stained relatively prominently in both groups. Animals receiving IP injections exhibited higher FITC-DEX uptakes by the SGs and OC, whereas IT injection triggered higher-level FITC-DEX accumulation by the OC and LWs. Flow cytometry revealed that intracochlear FITC-DEX uptake by IT-injected animals was higher and more prolonged than in animals subjected to IP injections. We thus describe differences in cochlear steroid distributions after systemic and IT injections. This finding could help our understanding of the pharmacokinetics of steroids in the cochlea. NA. Laryngoscope, 128:189-194, 2018. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

Imaging cochlear soft tissue displacement with coherent x-rays

NASA Astrophysics Data System (ADS)

Rau, Christoph; Richter, Claus-Peter

2015-10-01

At present, imaging of cochlear mechanics at mid-cochlear turns has not been accomplished. Although challenging, this appears possible with partially coherent hard x-rays. The present study shows results from stroboscopic x-ray imaging of a test object at audio frequencies. The vibration amplitudes were quantified. In a different set of experiments, an intact and calcified gerbil temporal bone was used to determine displacements of the reticular lamina, tectorial membrane, and Reissner’s membrane with the Lucas and Kanade video flow algorithm. The experiments validated high frequency x-ray imaging and imaging in a calcified cochlea. The present work is key for future imaging of cochlear micromechanics at a high spatial resolution.

Effects of nitric oxide synthase inhibitor on cochlear blood flow.

PubMed

Hoshijima, Hideaki; Makimoto, Kazuo; Noi, Osamu; Ohinata, Yoshimitsu; Takenaka, Hiroshi

2002-09-01

We observed in rats the changes in cochlear blood flow (CoBF) and cutaneous blood flow of the abdominal wall (AbBF) after the administration of the NO synthase inhibitor, N-nitro-L-arginine-methyl ester (L-NAME). Ten minutes after i.v. infusion of L-NAME (0.2, 1, 5, 10 mg/kg), L-arginine, which is a substrate of NO, was infused (100 mg/kg) i.v. Employing a laser Doppler flowmeter, the changes in blood flow were recorded from the basal turn of the right cochlea or the abdominal wall and blood pressure (BP) was recorded from the left femoral artery simultaneously. Vascular conductance (VC) was calculated from CoBF/mean BP (cochlear VC) or AbBF/mean BP (abdominal VC). The findings in rats generally agreed with those in guinea pigs [Brechtelsbauer et al., Hear. Res. 77 (1994) 38-42]. Intravenous infusion of L-NAME produced a dose-dependent depression of cochlear VC at 0.2 mg/kg (-18.9), 1 mg/kg (-37.9%), 5 mg/kg (-45.8%) and 10 mg/kg (-48.3%). AbBF also decreased after infusion of L-NAME (5 mg/kg) but to a lesser degree (-41.1% in VC) with no significance compared to CoBF (5 mg/kg). Infusion of L-arginine partially reversed the CoBF decrease caused by L-NAME. The group of 0.2 mg/kg infusion of L-NAME showed the largest degree of recovery with L-arginine, while the 10 mg/kg group showed the smallest. The decrease in AbBF did not recover substantially with L-arginine, the degree being less than that of each group in the CoBF experiment. It was suggested that the NO/soluble guanylate cyclase/cGMP system is more active in the cochlear microcirculation. With the round window (RW) application of 1% L-NAME (2 microl), cochlear VC was decreased by 21.6%, which was closest to that of the 0.2 mg/kg group of L-NAME i.v. infusion. The cochlear VC depression after local application of L-NAME did not show any recovery (-0.3%) by RW application of 5% L-arginine (2 microl) 25 min after L-NAME application; a slight gradual increase was observed when a higher concentration (20%) of L-arginine was applied to the RW. We propose that i.v. infusions of L-NAME and L-arginine primarily affect the precapillary arteriole of the spiral modiolar artery which effectively regulates microcirculation as a resistance vessel, and that RW application affects the vessels of the lateral wall, not the spiral modiolar artery because of the difficulty of substance diffusion.

Gain and frequency tuning within the mouse cochlear apex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oghalai, John S.; Raphael, Patrick D.; Gao, Simon

Normal mammalian hearing requires cochlear outer hair cell active processes that amplify the traveling wave with high gain and sharp tuning, termed cochlear amplification. We have used optical coherence tomography to study cochlear amplification within the apical turn of the mouse cochlea. We measured not only classical basilar membrane vibratory tuning curves but also vibratory responses from the rest of the tissues that compose the organ of Corti. Basilar membrane tuning was sharp in live mice and broad in dead mice, whereas other regions of the organ of Corti demonstrated phase shifts consistent with additional filtering beyond that provided bymore » basilar membrane mechanics. We use these experimental data to support a conceptual framework of how cochlear amplification is tuned within the mouse cochlear apex. We will also study transgenic mice with targeted mutations that affect different biomechanical aspects of the organ of Corti in an effort to localize the underlying processes that produce this additional filtering.« less

An automated A-value measurement tool for accurate cochlear duct length estimation.

PubMed

Iyaniwura, John E; Elfarnawany, Mai; Ladak, Hanif M; Agrawal, Sumit K

2018-01-22

There has been renewed interest in the cochlear duct length (CDL) for preoperative cochlear implant electrode selection and postoperative generation of patient-specific frequency maps. The CDL can be estimated by measuring the A-value, which is defined as the length between the round window and the furthest point on the basal turn. Unfortunately, there is significant intra- and inter-observer variability when these measurements are made clinically. The objective of this study was to develop an automated A-value measurement algorithm to improve accuracy and eliminate observer variability. Clinical and micro-CT images of 20 cadaveric cochleae specimens were acquired. The micro-CT of one sample was chosen as the atlas, and A-value fiducials were placed onto that image. Image registration (rigid affine and non-rigid B-spline) was applied between the atlas and the 19 remaining clinical CT images. The registration transform was applied to the A-value fiducials, and the A-value was then automatically calculated for each specimen. High resolution micro-CT images of the same 19 specimens were used to measure the gold standard A-values for comparison against the manual and automated methods. The registration algorithm had excellent qualitative overlap between the atlas and target images. The automated method eliminated the observer variability and the systematic underestimation by experts. Manual measurement of the A-value on clinical CT had a mean error of 9.5 ± 4.3% compared to micro-CT, and this improved to an error of 2.7 ± 2.1% using the automated algorithm. Both the automated and manual methods correlated significantly with the gold standard micro-CT A-values (r = 0.70, p < 0.01 and r = 0.69, p < 0.01, respectively). An automated A-value measurement tool using atlas-based registration methods was successfully developed and validated. The automated method eliminated the observer variability and improved accuracy as compared to manual measurements by experts. This open-source tool has the potential to benefit cochlear implant recipients in the future.

Coupling Active Hair Bundle Mechanics, Fast Adaptation, and Somatic Motility in a Cochlear Model

PubMed Central

Meaud, Julien; Grosh, Karl

2011-01-01

One of the central questions in the biophysics of the mammalian cochlea is determining the contributions of the two active processes, prestin-based somatic motility and hair bundle (HB) motility, to cochlear amplification. HB force generation is linked to fast adaptation of the transduction current via a calcium-dependent process and somatic force generation is driven by the depolarization caused by the transduction current. In this article, we construct a global mechanical-electrical-acoustical mathematical model of the cochlea based on a three-dimensional fluid representation. The global cochlear model is coupled to linearizations of nonlinear somatic motility and HB activity as well as to the micromechanics of the passive structural and electrical elements of the cochlea. We find that the active HB force alone is not sufficient to power high frequency cochlear amplification. However, somatic motility can overcome resistor-capacitor filtering by the basolateral membrane and deliver sufficient mechanical energy for amplification at basal locations. The results suggest a new theory for high frequency active cochlear mechanics, in which fast adaptation controls the transduction channel sensitivity and thereby the magnitude of the energy delivered by somatic motility. PMID:21641302

Coupling active hair bundle mechanics, fast adaptation, and somatic motility in a cochlear model.

PubMed

Meaud, Julien; Grosh, Karl

2011-06-08

One of the central questions in the biophysics of the mammalian cochlea is determining the contributions of the two active processes, prestin-based somatic motility and hair bundle (HB) motility, to cochlear amplification. HB force generation is linked to fast adaptation of the transduction current via a calcium-dependent process and somatic force generation is driven by the depolarization caused by the transduction current. In this article, we construct a global mechanical-electrical-acoustical mathematical model of the cochlea based on a three-dimensional fluid representation. The global cochlear model is coupled to linearizations of nonlinear somatic motility and HB activity as well as to the micromechanics of the passive structural and electrical elements of the cochlea. We find that the active HB force alone is not sufficient to power high frequency cochlear amplification. However, somatic motility can overcome resistor-capacitor filtering by the basolateral membrane and deliver sufficient mechanical energy for amplification at basal locations. The results suggest a new theory for high frequency active cochlear mechanics, in which fast adaptation controls the transduction channel sensitivity and thereby the magnitude of the energy delivered by somatic motility. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells

PubMed Central

Johnson, Stuart L.; Eckrich, Tobias; Kuhn, Stephanie; Zampini, Valeria; Franz, Christoph; Ranatunga, Kishani M.; Roberts, Terri P.; Masetto, Sergio; Knipper, Marlies; Kros, Corné J.; Marcotti, Walter

2011-01-01

Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion cells and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials are intrinsically generated by immature IHCs of altricial rodents and that apical IHCs exhibit bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter ACh, by fine-tuning the IHC’s resting membrane potential (Vm), is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the Vm of apical and basal IHCs by activating SK2 channels. We hypothesize that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway. PMID:21572434

Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells.

PubMed

Johnson, Stuart L; Eckrich, Tobias; Kuhn, Stephanie; Zampini, Valeria; Franz, Christoph; Ranatunga, Kishani M; Roberts, Terri P; Masetto, Sergio; Knipper, Marlies; Kros, Corné J; Marcotti, Walter

2011-06-01

Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials were intrinsically generated by immature IHCs of altricial rodents and that apical IHCs showed bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter acetylcholine fine-tunes the IHC's resting membrane potential (V(m)), and as such is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the V(m) of apical and basal IHCs by triggering small-conductance Ca(2+)-activated K(+) (SK2) channels. We propose that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway.

Cochlear pharmacokinetics with local inner ear drug delivery using a three-dimensional finite-element computer model.

PubMed

Plontke, Stefan K; Siedow, Norbert; Wegener, Raimund; Zenner, Hans-Peter; Salt, Alec N

2007-01-01

Cochlear fluid pharmacokinetics can be better represented by three-dimensional (3D) finite-element simulations of drug dispersal. Local drug deliveries to the round window membrane are increasingly being used to treat inner ear disorders. Crucial to the development of safe therapies is knowledge of drug distribution in the inner ear with different delivery methods. Computer simulations allow application protocols and drug delivery systems to be evaluated, and may permit animal studies to be extrapolated to the larger cochlea of the human. A finite-element 3D model of the cochlea was constructed based on geometric dimensions of the guinea pig cochlea. Drug propagation along and between compartments was described by passive diffusion. To demonstrate the potential value of the model, methylprednisolone distribution in the cochlea was calculated for two clinically relevant application protocols using pharmacokinetic parameters derived from a prior one-dimensional (1D) model. In addition, a simplified geometry was used to compare results from 3D with 1D simulations. For the simplified geometry, calculated concentration profiles with distance were in excellent agreement between the 1D and the 3D models. Different drug delivery strategies produce very different concentration time courses, peak concentrations and basal-apical concentration gradients of drug. In addition, 3D computations demonstrate the existence of substantial gradients across the scalae in the basal turn. The 3D model clearly shows the presence of drug gradients across the basal scalae of guinea pigs, demonstrating the necessity of a 3D approach to predict drug movements across and between scalae with larger cross-sectional areas, such as the human, with accuracy. This is the first model to incorporate the volume of the spiral ligament and to calculate diffusion through this structure. Further development of the 3D model will have to incorporate a more accurate geometry of the entire inner ear and incorporate more of the specific processes that contribute to drug removal from the inner ear fluids. Appropriate computer models may assist in both drug and drug delivery system design and can thus accelerate the development of a rationale-based local drug delivery to the inner ear and its successful establishment in clinical practice. Copyright 2007 S. Karger AG, Basel.

Cochlear Pharmacokinetics with Local Inner Ear Drug Delivery Using a Three-Dimensional Finite-Element Computer Model

PubMed Central

Plontke, Stefan K.; Siedow, Norbert; Wegener, Raimund; Zenner, Hans-Peter; Salt, Alec N.

2006-01-01

Hypothesis: Cochlear fluid pharmacokinetics can be better represented by three-dimensional (3D) finite-element simulations of drug dispersal. Background: Local drug deliveries to the round window membrane are increasingly being used to treat inner ear disorders. Crucial to the development of safe therapies is knowledge of drug distribution in the inner ear with different delivery methods. Computer simulations allow application protocols and drug delivery systems to be evaluated, and may permit animal studies to be extrapolated to the larger cochlea of the human. Methods: A finite-element 3D model of the cochlea was constructed based on geometric dimensions of the guinea pig cochlea. Drug propagation along and between compartments was described by passive diffusion. To demonstrate the potential value of the model, methylprednisolone distribution in the cochlea was calculated for two clinically relevant application protocols using pharmacokinetic parameters derived from a prior one-dimensional (1D) model. In addition, a simplified geometry was used to compare results from 3D with 1D simulations. Results: For the simplified geometry, calculated concentration profiles with distance were in excellent agreement between the 1D and the 3D models. Different drug delivery strategies produce very different concentration time courses, peak concentrations and basal-apical concentration gradients of drug. In addition, 3D computations demonstrate the existence of substantial gradients across the scalae in the basal turn. Conclusion: The 3D model clearly shows the presence of drug gradients across the basal scalae of guinea pigs, demonstrating the necessity of a 3D approach to predict drug movements across and between scalae with larger cross-sectional areas, such as the human, with accuracy. This is the first model to incorporate the volume of the spiral ligament and to calculate diffusion through this structure. Further development of the 3D model will have to incorporate a more accurate geometry of the entire inner ear and incorporate more of the specific processes that contribute to drug removal from the inner ear fluids. Appropriate computer models may assist in both drug and drug delivery system design and can thus accelerate the development of a rationale-based local drug delivery to the inner ear and its successful establishment in clinical practice. PMID:17119332

Configuration optimization and experimental accuracy evaluation of a bone-attached, parallel robot for skull surgery.

PubMed

Kobler, Jan-Philipp; Nuelle, Kathrin; Lexow, G Jakob; Rau, Thomas S; Majdani, Omid; Kahrs, Lueder A; Kotlarski, Jens; Ortmaier, Tobias

2016-03-01

Minimally invasive cochlear implantation is a novel surgical technique which requires highly accurate guidance of a drilling tool along a trajectory from the mastoid surface toward the basal turn of the cochlea. The authors propose a passive, reconfigurable, parallel robot which can be directly attached to bone anchors implanted in a patient's skull, avoiding the need for surgical tracking systems. Prior to clinical trials, methods are necessary to patient specifically optimize the configuration of the mechanism with respect to accuracy and stability. Furthermore, the achievable accuracy has to be determined experimentally. A comprehensive error model of the proposed mechanism is established, taking into account all relevant error sources identified in previous studies. Two optimization criteria to exploit the given task redundancy and reconfigurability of the passive robot are derived from the model. The achievable accuracy of the optimized robot configurations is first estimated with the help of a Monte Carlo simulation approach and finally evaluated in drilling experiments using synthetic temporal bone specimen. Experimental results demonstrate that the bone-attached mechanism exhibits a mean targeting accuracy of [Formula: see text] mm under realistic conditions. A systematic targeting error is observed, which indicates that accurate identification of the passive robot's kinematic parameters could further reduce deviations from planned drill trajectories. The accuracy of the proposed mechanism demonstrates its suitability for minimally invasive cochlear implantation. Future work will focus on further evaluation experiments on temporal bone specimen.

Mechanisms of Hearing Loss after Blast Injury to the Ear

PubMed Central

Cho, Sung-Il; Gao, Simon S.; Xia, Anping; Wang, Rosalie; Salles, Felipe T.; Raphael, Patrick D.; Abaya, Homer; Wachtel, Jacqueline; Baek, Jongmin; Jacobs, David; Rasband, Matthew N.; Oghalai, John S.

2013-01-01

Given the frequent use of improvised explosive devices (IEDs) around the world, the study of traumatic blast injuries is of increasing interest. The ear is the most common organ affected by blast injury because it is the body’s most sensitive pressure transducer. We fabricated a blast chamber to re-create blast profiles similar to that of IEDs and used it to develop a reproducible mouse model to study blast-induced hearing loss. The tympanic membrane was perforated in all mice after blast exposure and found to heal spontaneously. Micro-computed tomography demonstrated no evidence for middle ear or otic capsule injuries; however, the healed tympanic membrane was thickened. Auditory brainstem response and distortion product otoacoustic emission threshold shifts were found to be correlated with blast intensity. As well, these threshold shifts were larger than those found in control mice that underwent surgical perforation of their tympanic membranes, indicating cochlear trauma. Histological studies one week and three months after the blast demonstrated no disruption or damage to the intra-cochlear membranes. However, there was loss of outer hair cells (OHCs) within the basal turn of the cochlea and decreased spiral ganglion neurons (SGNs) and afferent nerve synapses. Using our mouse model that recapitulates human IED exposure, our results identify that the mechanisms underlying blast-induced hearing loss does not include gross membranous rupture as is commonly believed. Instead, there is both OHC and SGN loss that produce auditory dysfunction. PMID:23840874

[Site of prelingual cochlear stimulation and its effect on electrically evoked compound action potentials and refractory using the Nucleus 24 standard].

PubMed

Ma, R Y; Li, W; Jiang, X J

2016-12-01

Objective: To investigate the correlation between the site of prelingual cochlear stimulation and its effect on electrically evoked compound action potentials. Method: Recordings of auditory nerve responses were conducted in 32 prelingual subjects to demonstrate the feasibility of ECAP recordings using the nerve response telemetry(NRT) feature of the Nucleus CI24R(CA) system software. These recordings were then analyzed based on the site of cochlear stimulation defined as basal, middle and apical to determine if the amplitude, threshold and slope of the amplitude growth function and the refractory time differs depending on the region of stimulation. Result: Findings of our prelingual children showed significant differences in the ECAP recordings depending on the stimulation site. Comparing the apical with the basal region, on average higher amplitudes, lower thresholds and steeper slopes of the amplitude growth function hadbeen observed. The refractory time showed an overall dependence on cochlear region; however post-hoc tests showed no significant effect between individual regions. Conclusion: Obtaining ECAP recordings is also possible in the most apical region of the cochlea. However, differences can be observed depending on the region of the cochlea stimulated. Specifically, significant higher ECAP amplitude, lower thresholds and steeper amplitude growth function slopes have been observed in the apical region. These differences between prelingual children and adults could be explained by the location of the stimulating electrode with respect to the neural tissue in the cochlea, a higher density, or an increased neural survival rate of neural tissue in the apex. Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.

Music activities and responses of young cochlear implant recipients.

PubMed

van Besouw, Rachel M; Grasmeder, Mary L; Hamilton, Mary E; Baumann, Sarah E

2011-05-01

The development of auditory receptive skills and spoken language is often delayed in children who use cochlear implants, which may affect their appreciation of and responses to music. This in turn may be interpreted as disinterest in music. A questionnaire was developed to determine whether differences in exposure and responses to music exist between young cochlear implant recipients and their normally hearing peers. The questionnaire was developed by a multidisciplinary team and distributed to parents of preschool children with normal hearing and to parents of preschool children who had been implanted at least one year prior. The cochlear implant group comprised 23 children and was gender and age matched (within ±2 months) to a group of children with normal hearing. Young cochlear implant recipients receive similar exposure to audiovisual music media, parental singing and musical instruments at home. However, the data suggest that they receive less exposure to children's music presented without visual stimuli. Parents also reported less sophisticated responses to music for this group. The findings of this study have important implications concerning the provision of age-appropriate music habilitation materials and activities for young cochlear implant recipients.

Development of HEATHER for cochlear implant stimulation using a new modeling workflow.

PubMed

Tran, Phillip; Sue, Andrian; Wong, Paul; Li, Qing; Carter, Paul

2015-02-01

The current conduction pathways resulting from monopolar stimulation of the cochlear implant were studied by developing a human electroanatomical total head reconstruction (namely, HEATHER). HEATHER was created from serially sectioned images of the female Visible Human Project dataset to encompass a total of 12 different tissues, and included computer-aided design geometries of the cochlear implant. Since existing methods were unable to generate the required complexity for HEATHER, a new modeling workflow was proposed. The results of the finite-element analysis agree with the literature, showing that the injected current exits the cochlea via the modiolus (14%), the basal end of the cochlea (22%), and through the cochlear walls (64%). It was also found that, once leaving the cochlea, the current travels to the implant body via the cranial cavity or scalp. The modeling workflow proved to be robust and flexible, allowing for meshes to be generated with substantial user control. Furthermore, the workflow could easily be employed to create realistic anatomical models of the human head for different bioelectric applications, such as deep brain stimulation, electroencephalography, and other biophysical phenomena.

Effects of carbogen on cochlear blood flow and hearing function following acute acoustic trauma in guinea pigs.

PubMed

Zhao, Jing; Sun, Jianjun; Liu, Yang

2012-10-01

Disturbances of microcirculation and hemorheological changes in the inner ear are the results of noise-induced hearing loss (NIHL). Both the disturbances of microcirculation and hemorheological changes are the etiologies of NIHL development, but they are also the results. Although previous reports that inhalation of high concentration of CO(2) may increase cochlear blood flow (CoBF), the effects of carbogen on the cochlear microcirculation and NIHL remain unclear. Changes induced by noise, carbogen and pure oxygen within the cochlear lateral wall microvasculature and in hearing thresholds were observed in guinea pigs using intravital microscopy and the auditory brainstem response. At the same time, arterial oxygen saturation and morphologic changes of cochlear hair cells were observed. Carbogen inhalation increased vessel diameters and blood flow velocities. Hearing thresholds elevation in the carbogen group was smaller than those in the control and oxygen group (p <0.05). Carbogen inhalation produced a trend toward less threshold shift after noise exposure, which reached statistical significance after day 3 (p <0.01). Respiratory acidosis was not found in our study. The segmented basal membranes of Corti in three groups indicated that no losses or discorders of hair cells were found. Carbogen inhalation can preserve hearing in animal models after acute acoustic trauma. Copyright © 2012 IMSS. All rights reserved.

Intracochlear administration of steroids with a catheter during human cochlear implantation: a safety and feasibility study.

PubMed

Prenzler, Nils K; Salcher, Rolf; Timm, Max; Gaertner, Lutz; Lenarz, Thomas; Warnecke, Athanasia

2018-05-14

Suppression of foreign body reaction, improvement of electrode-nerve interaction, and preservation of residual hearing are essential research topics in cochlear implantation. Intracochlear pharmaco- or cell-based therapies can open new horizons in this field. Local drug delivery strategies are desirable as higher local concentrations of agents can be realized and side effects can be minimized compared to systemic administrations. When administered locally at accessible, basal parts of the cochlea, drugs reach apical regions later and in much lower concentrations due to poor diffusion patterns in cochlear fluids. Therefore, new devices are needed to warrant rapid distribution of agents into all parts of the cochlea. Five patients received a deep intracochlear injection of triamcinolone with a specifically designed cochlear catheter during cochlear implantation right before inserting a cochlear implant electrode. As a measure for formation of fibrous tissue around the electrode, electrical impedances were measured in the operation room and over 4 months thereafter. No adverse events were observed peri- and postoperatively. The handling of the device was easy. Severe damage to the microstructure of the cochlea was excluded as far as possible by cone beam computed tomography and vestibular testing. A delayed rise of the impedances was seen in the catheter group compared to controls over all regions of the cochlea. A statistical significance, however, was only obtained at the midregion of the cochlea. Consequently, the cochlear catheter is a safe and feasible device for local drug delivery of pharmaceutical agents into deeper regions of the cochlea.

A Histological Study of Scala Communis with Radiological Implications

PubMed Central

Makary, Chadi; Shin, Jennifer; Caruso, Paul; Curtin, Hugh; Merchant, Saumil

2010-01-01

Objectives Scala communis or interscalar septum (IS) defect is a developmental abnormality of the inner ear characterized by a dehiscence in the partition separating the turns of the cochlea. The goals of the present study were to (1) study this anomaly and describe its characteristics compared to control ears using a histological analysis of temporal bones, (2) discuss radiological implications regarding its diagnosis, and (3) describe its embryological derivation. Methods Out of 1775 temporal bones assessed, 22 specimens were found to have scala communis in cochleae containing all 3 turns (basal, middle and apical). These 22 ears were studied in detail by qualitative and quantitative methods using light microscopy. Results Scala communis occurred as an isolated inner ear anomaly, or in association with other congenital cochlear and/or vestibular anomalies. The defect occurred most often between the middle and apical turns of the cochlea. Compared to control ears, scala communis ears were found to have a smaller modiolar area (p < 0.0001) and flattening of the interscalar ridge (point of attachment of the IS to the inner lumen of the cochlea; p < 0.0001). Scala communis was compatible with normal hearing. Conclusions Flattening of the interscalar ridge has the potential to improve the diagnosis of scala communis in patients using CT scanning. The anomaly may result from a mesodermal defect such as excessive resorption of mesenchyme during the formation of the scalae, an error in the formation of bone, or both. PMID:20389062

A histological study of scala communis with radiological implications.

PubMed

Makary, Chadi; Shin, Jennifer; Caruso, Paul; Curtin, Hugh; Merchant, Saumil

2010-01-01

Scala communis or interscalar septum (IS) defect is a developmental abnormality of the inner ear characterized by a dehiscence in the partition separating the turns of the cochlea. The goals of the present study were to (1) study this anomaly and describe its characteristics compared to control ears using a histological analysis of temporal bones, (2) discuss radiological implications regarding its diagnosis, and (3) describe its embryological derivation. Out of 1775 temporal bones assessed, 22 specimens were found to have scala communis in cochleae containing all 3 turns (basal, middle and apical). These 22 ears were studied in detail by qualitative and quantitative methods using light microscopy. Scala communis occurred as an isolated inner ear anomaly, or in association with other congenital cochlear and/or vestibular anomalies. The defect occurred most often between the middle and apical turns of the cochlea. Compared to control ears, scala communis ears were found to have a smaller modiolar area (p < 0.0001) and flattening of the interscalar ridge (point of attachment of the IS to the inner lumen of the cochlea; p < 0.0001). Scala communis was compatible with normal hearing. Flattening of the interscalar ridge has the potential to improve the diagnosis of scala communis in patients using CT scanning. The anomaly may result from a mesodermal defect such as excessive resorption of mesenchyme during the formation of the scalae, an error in the formation of bone, or both. Copyright © 2010 S. Karger AG, Basel.

Cochlear dysfunction in hyperuricemia: otoacoustic emission analysis.

PubMed

Hamed, Sherifa A; El-Attar, Amal M

2010-01-01

The objective of this study is to provide evidence that primary hyperuricemia is associated with cochlear dysfunction as other metabolic diseases that interfere with cell metabolism. Cochlear function was evaluated in 25 subjects with asymptomatic hyperuricemia using routine diagnostic audiometry along with transient evoked and distortion product otoacoustic emissions (TEOAE and DPOAE, respectively). To support the notion that vascular compromise was a significant underlying factor for such cochlear dysfunction, we assessed vascular anatomical and functional states through measuring the common carotid artery intima-media thickness and flow velocity of the basal intracranial vessels. Compared with control subjects, reduced response levels of TEOAEs (P < .01) and amplitudes of DPOAEs (P < .001) were detected at higher frequencies. The reduced DPOAE levels at 5 kHz and TEOAEs at 4 kHz correlated significantly with uric acid (P < .05; P < .01), patients' age (P < .06; P < .05), duration since diagnosis of hyperuricemia (P < .05; P < .001), common carotid artery intima-media thickness (P < .05), mean flow velocities of middle cerebral arteries (P < .05), and vertebral arteries (P < .01). Multivariate analysis showed that the abnormalities at higher frequencies were significantly correlated with the duration and degree of hyperuricemia. These data suggest that subclinical changes in cochlear function are associated with hyperuricemia. They support the usefulness of otoacoustic emissions in early detection of cochlear dysfunction. It is possible that hyperuricemia could be accompanied by increased stiffness and/or compromise of blood supply of the outer hair cells, which will impair their electromotile response. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Preliminary Mathematical Model for Jet Fuel Exacerbated Noise-Induced Hearing Loss

DTIC Science & Technology

2013-01-01

and blood vessel damage (stria vascularis) with reductions in cochlear blood flow , which in turn mediates further damage as a result of reductions in...2006. The role of oxidative stress in noise-induced hearing loss. Ear Hear. 27:1-19. Hillerdal, M. 1987. Cochlear blood flow in the rat. A...OF TABLES Table 1. Bodyweight and combined cochlea weight and fractions from F344 rat kinetic study ....7 Table 2. Blood flow values for rat

Improved Auditory Nerve Survival with Nanoengineered Supraparticles for Neurotrophin Delivery into the Deafened Cochlea

PubMed Central

Tan, Justin; Wang, Yajun; Caruso, Frank; Shepherd, Robert K.

2016-01-01

Cochlear implants electrically stimulate spiral ganglion neurons (SGNs) in order to provide speech cues to severe-profoundly deaf patients. In normal hearing cochleae the SGNs depend on endogenous neurotrophins secreted by sensory cells in the organ of Corti for survival. SGNs gradually degenerate following deafness and consequently there is considerable interest in developing clinically relevant strategies to provide exogenous neurotrophins to preserve SGN survival. The present study investigated the safety and efficacy of a drug delivery system for the cochlea using nanoengineered silica supraparticles. In the present study we delivered Brain-derived neurotrophic factor (BDNF) over a period of four weeks and evaluated SGN survival as a measure of efficacy. Supraparticles were bilaterally implanted into the basal turn of cochleae in profoundly deafened guinea pigs. One ear received BDNF-loaded supraparticles and the other ear control (unloaded) supraparticles. After one month of treatment the cochleae were examined histologically. There was significantly greater survival of SGNs in cochleae that received BDNF supraparticles compared to the contralateral control cochleae (repeated measures ANOVA, p = 0.009). SGN survival was observed over a wide extent of the cochlea. The supraparticles were well tolerated within the cochlea with a tissue response that was localised to the site of implantation in the cochlear base. Although mild, the tissue response was significantly greater in cochleae treated with BDNF supraparticles compared to the controls (repeated measures ANOVA, p = 0.003). These data support the clinical potential of this technology particularly as the supraparticles can be loaded with a variety of therapeutic drugs. PMID:27788219

Distribution of Vesicular Glutamate Transporter 2 and Ionotropic Glutamate Receptors in the Auditory Ganglion and Cochlear Nuclei of Pigeons (Columba livia).

PubMed

Karim, M R; Atoji, Y

2016-02-01

Glutamate is a principal excitatory neurotransmitter in the auditory system. Our previous studies revealed localization of glutamate receptor mRNAs in the pigeon cochlear nuclei, suggesting the existence of glutamatergic input from the auditory nerve to the brainstem. This study demonstrated localization of mRNAs for vesicular glutamate transporter 2 (vGluT2) and ionotropic glutamate receptors (AMPA, kainate and NMDA) in the auditory ganglion (AG) and cochlear nuclei (magnocellular, angular and laminar nuclei). VGluT2 mRNA was intensely expressed in AG and intensely or moderately in the cochlear nuclei. The AG and cochlear nuclei showed intense-to-moderate mRNA signals for GluA2, GluA3, GluA4, GluK4 and GluN1. These results suggest that the pigeon AG neurons receives glutamatergic input from hair cells and in turn projects to the magnocellular and angular nuclei. Glutamate may play a pivotal role in the excitatory synapse transmission in the peripheral auditory pathway of birds. © 2015 Blackwell Verlag GmbH.

Progressive age-dependence and frequency difference in the effect of gap junctions on active cochlear amplification and hearing.

PubMed

Zong, Liang; Chen, Jin; Zhu, Yan; Zhao, Hong-Bo

2017-07-22

Mutations of Connexin 26 (Cx26, GJB2), which is a predominant gap junction isoform in the cochlea, can induce high incidence of nonsyndromic hearing loss. We previously found that targeted-deletion of Cx26 in supporting Deiters cells and outer pillar cells in the cochlea can influence outer hair cell (OHC) electromotility and reduce active cochlear amplification leading to hearing loss, even though there are no gap junction connexin expressions in the auditory sensory hair cells. Here, we further report that hearing loss and the reduction of active amplification in the Cx26 targeted-deletion mice are progressive and different at high and low frequency regions, first occurring in the high frequency region and then progressively extending to the middle and low frequency regions with mouse age increased. The speed of hearing loss extending was fast in the basal high frequency region and slow in the apical low frequency region, showing a logarithmic function with mouse age. Before postnatal day 25, there were no significant hearing loss and the reduction of active cochlear amplification in the low frequency region. Hearing loss and the reduction of active cochlear amplification also had frequency difference, severe and large in the high frequency regions. These new data indicate that the effect of gap junction on active cochlear amplification is progressive, but, consistent with our previous report, exists in both high and low frequency regions in adulthood. These new data also suggest that cochlear gap junctions may have an important role in age-related hearing loss. Copyright © 2017 Elsevier Inc. All rights reserved.

Neurotrophin gene therapy for sustained neural preservation after deafness.

PubMed

Atkinson, Patrick J; Wise, Andrew K; Flynn, Brianna O; Nayagam, Bryony A; Hume, Clifford R; O'Leary, Stephen J; Shepherd, Robert K; Richardson, Rachael T

2012-01-01

The cochlear implant provides auditory cues to profoundly deaf patients by electrically stimulating the residual spiral ganglion neurons. These neurons, however, undergo progressive degeneration after hearing loss, marked initially by peripheral fibre retraction and ultimately culminating in cell death. This research aims to use gene therapy techniques to both hold and reverse this degeneration by providing a sustained and localised source of neurotrophins to the deafened cochlea. Adenoviral vectors containing green fluorescent protein, with or without neurotrophin-3 and brain derived neurotrophic factor, were injected into the lower basal turn of scala media of guinea pigs ototoxically deafened one week prior to intervention. This single injection resulted in localised and sustained gene expression, principally in the supporting cells within the organ of Corti. Guinea pigs treated with adenoviral neurotrophin-gene therapy had greater neuronal survival compared to contralateral non-treated cochleae when examined at 7 and 11 weeks post injection. Moreover; there was evidence of directed peripheral fibre regrowth towards cells expressing neurotrophin genes after both treatment periods. These data suggest that neurotrophin-gene therapy can provide sustained protection of spiral ganglion neurons and peripheral fibres after hearing loss.

Development of a Microfluidics-Based Intracochlear Drug Delivery Device

PubMed Central

Sewell, William F.; Borenstein, Jeffrey T.; Chen, Zhiqiang; Fiering, Jason; Handzel, Ophir; Holmboe, Maria; Kim, Ernest S.; Kujawa, Sharon G.; McKenna, Michael J.; Mescher, Mark M.; Murphy, Brian; Leary Swan, Erin E.; Peppi, Marcello; Tao, Sarah

2009-01-01

Background Direct delivery of drugs and other agents into the inner ear will be important for many emerging therapies, including the treatment of degenerative disorders and guiding regeneration. Methods We have taken a microfluidics/MEMS (MicroElectroMechanical Systems) technology approach to develop a fully implantable reciprocating inner-ear drug-delivery system capable of timed and sequenced delivery of agents directly into perilymph of the cochlea. Iterations of the device were tested in guinea pigs to determine the flow characteristics required for safe and effective delivery. For these tests, we used the glutamate receptor blocker DNQX, which alters auditory nerve responses but not cochlear distortion product otoacoustic emissions. Results We have demonstrated safe and effective delivery of agents into the scala tympani. Equilibration of the drug in the basal turn occurs rapidly (within tens of minutes) and is dependent on reciprocating flow parameters. Conclusion We have described a prototype system for the direct delivery of drugs to the inner ear that has the potential to be a fully implantable means for safe and effective treatment of hearing loss and other diseases. PMID:19923811

Neurotrophins and electrical stimulation for protection and repair of spiral ganglion neurons following sensorineural hearing loss

PubMed Central

Shepherd, Robert K.; Coco, Anne; Epp, Stephanie B.

2008-01-01

Exogenous neurotrophins (NTs) have been shown to rescue spiral ganglion neurons (SGNs) from degeneration following a sensorineural hearing loss (SNHL). Furthermore, chronic electrical stimulation (ES) has been shown to retard SGN degeneration in some studies but not others. Since there is evidence of even greater SGN rescue when NT administration is combined with ES, we examined whether chronic ES can maintain SGN survival long after cessation of NT delivery. Young adult guinea pigs were profoundly deafened using ototoxic drugs; five days later they were unilaterally implanted with an electrode array and drug delivery system. Brain derived neurotrophic factor (BDNF) was continuously delivered to the scala tympani over a four week period while the animal simultaneously received ES via bipolar electrodes in the basal turn (i.e. turn 1) scala tympani. One cohort (n=5) received ES for six weeks (i.e. including a two week period after the cessation of BDNF delivery; ES6); a second cohort (n=5) received ES for 10 weeks (i.e. a six week period following cessation of BDNF delivery; ES10). The cochleae were harvested for histology and SGN density determined for each cochlear turn for comparison with normal hearing controls (n=4). The withdrawal of BDNF resulted in a rapid loss of SGNs in turns 2–4 of the deafened/BDNF-treated cochleae; this was significant as early as two weeks following removal of the NT when compared with normal controls (p<0.05). Importantly, there was not a significant reduction in SGNs in turn 1 (i.e. adjacent to the electrode array) two and six weeks after NT removal, as compared with normal controls. This result suggests that chronic ES can prevent the rapid loss of SGNs that occurs after the withdrawal of exogenous NTs. Implications for the clinical delivery of NTs are discussed. PMID:18243608

ACF7 is a hair-bundle antecedent, positioned to integrate cuticular plate actin and somatic tubulin.

PubMed

Antonellis, Patrick J; Pollock, Lana M; Chou, Shih-Wei; Hassan, Ahmed; Geng, Ruishuang; Chen, Xi; Fuchs, Elaine; Alagramam, Kumar N; Auer, Manfred; McDermott, Brian M

2014-01-01

The precise morphology of the mechanosensitive hair bundle requires seamless integration of actin and microtubule networks. Here, we identify Acf7a (actin crosslinking family protein 7a) as a protein positioned to bridge these distinct cytoskeletal networks in hair cells. By imaging Acf7a-Citrine fusion protein in zebrafish and immunolabeling of vestibular and cochlear mouse hair cells, we show that Acf7a and ACF7 circumscribe, underlie, and are interwoven into the cuticular plate (CP), and they also encircle the basal body of the kinocilium. In cochlear hair cells, ACF7 localization is graded, with the highest concentration near each fonticulus--an area free of F-actin in the region of the CP that contains the basal body. During hair-cell development and regeneration, Acf7a precedes formation of the hair bundle and CP. Finally, electron tomography demonstrates that the ends of microtubules insert into the CP and are decorated with filamentous linkers connecting microtubules to the CP. These observations are consistent with ACF7 being a linker protein, which may shape the cytoskeleton of the hair cell early during hair-bundle genesis.

ACF7 Is a Hair-Bundle Antecedent, Positioned to Integrate Cuticular Plate Actin and Somatic Tubulin

PubMed Central

Antonellis, Patrick J.; Pollock, Lana M.; Chou, Shih-Wei; Hassan, Ahmed; Geng, Ruishuang; Chen, Xi; Fuchs, Elaine; Alagramam, Kumar N.; Auer, Manfred

2014-01-01

The precise morphology of the mechanosensitive hair bundle requires seamless integration of actin and microtubule networks. Here, we identify Acf7a (actin crosslinking family protein 7a) as a protein positioned to bridge these distinct cytoskeletal networks in hair cells. By imaging Acf7a–Citrine fusion protein in zebrafish and immunolabeling of vestibular and cochlear mouse hair cells, we show that Acf7a and ACF7 circumscribe, underlie, and are interwoven into the cuticular plate (CP), and they also encircle the basal body of the kinocilium. In cochlear hair cells, ACF7 localization is graded, with the highest concentration near each fonticulus—an area free of F-actin in the region of the CP that contains the basal body. During hair-cell development and regeneration, Acf7a precedes formation of the hair bundle and CP. Finally, electron tomography demonstrates that the ends of microtubules insert into the CP and are decorated with filamentous linkers connecting microtubules to the CP. These observations are consistent with ACF7 being a linker protein, which may shape the cytoskeleton of the hair cell early during hair-bundle genesis. PMID:24381291

Fitting prelingually deafened adult cochlear implant users based on electrode discrimination performance.

PubMed

Debruyne, Joke A; Francart, Tom; Janssen, A Miranda L; Douma, Kim; Brokx, Jan P L

2017-03-01

This study investigated the hypotheses that (1) prelingually deafened CI users do not have perfect electrode discrimination ability and (2) the deactivation of non-discriminable electrodes can improve auditory performance. Electrode discrimination difference limens were determined for all electrodes of the array. The subjects' basic map was subsequently compared to an experimental map, which contained only discriminable electrodes, with respect to speech understanding in quiet and in noise, listening effort, spectral ripple discrimination and subjective appreciation. Subjects were six prelingually deafened, late implanted adults using the Nucleus cochlear implant. Electrode discrimination difference limens across all subjects and electrodes ranged from 0.5 to 7.125, with significantly larger limens for basal electrodes. No significant differences were found between the basic map and the experimental map on auditory tests. Subjective appreciation was found to be significantly poorer for the experimental map. Prelingually deafened CI users were unable to discriminate between all adjacent electrodes. There was no difference in auditory performance between the basic and experimental map. Potential factors contributing to the absence of improvement with the experimental map include the reduced number of maxima, incomplete adaptation to the new frequency allocation, and the mainly basal location of deactivated electrodes.

Differences in perilymphatic space enhancement and adverse inflammatory reaction after intratympanic injection of two different gadolinium agents: A 9.4-T magnetic resonance imaging study.

PubMed

Park, Mina; Lee, Ho Sun; Kim, Hyeonjin; Oh, Seung Ha; Lee, Jun Ho; Suh, Myung-Whan

2016-03-01

To compare the inner ear enhancement after intratympanic injection of two widely used gadolinium (Gd) agents by 9.4 T micro-magnetic resonance imaging (MRI) and to investigate the effects of Gd on the inner ear. Twelve ears of six rats received intratympanic administration of 1/5 diluted Gd agents: gadoterate meglumine (Gd-DTPA) for the left ear and gadodiamide (Gd-DTPA-BMA) for the right ear. MRI was performed every 30 min from 1 to 4 h after administration. The normalized signal intensity was evaluated by quantitative analysis at each cochlear fluid compartment. Eight, six, and seven ears treated with Gd-DTPA, Gd-DPTA-BMA, and nothing as controls, respectively, were processed for histological evaluation after MRI. After hematoxylin & eosin staining, adverse inflammatory reactions were evaluated for turbid aggregation and lymphocytes. The perilymphatic enhancement of Gd-DTPA was superior to that of Gd-DTPA-BMA regardless of cochlear turn, compartment, and time point. Inflammatory reactions were found in 4/8 (50.0%) and 4/6 (66.6%) ears administered Gd-DTPA and Gd-DTPA-BMA, respectively. Regardless of the contrast agent used, inflammatory reactions were most definite in the scala tympani of the basal turn, i.e., near the round window. Slightly greater inflammatory reactions were observed in ears injected with Gd-DTPA-BMA compared to Gd-DTPA although the difference was not statistically significant. No inflammatory reaction was observed in any of the seven controls. The auditory brainstem response threshold was 11.8 ± 2.5 dB SPL before IT Gd injection and it did not change for up to 5 days (15.4 ± 6.6 dB SPL) post-injection. Gd-DTPA was superior to Gd-DTPA-BMA for visualization of the inner ear. Administration of diluted Gd agents intratympanically may induce considerable inflammatory reactions in the inner ear. Copyright © 2015 Elsevier B.V. All rights reserved.

Interrelated striated elements in vestibular hair cells of the rat

NASA Technical Reports Server (NTRS)

Ross, M. D.; Bourne, C.

1983-01-01

A series of interrelated striated organelles in types I and II vestibular hair cells of the rat which appear to be less developed in cochlear hair cells have been revealed by unusual fixation procedures, suggesting that contractile elements may play a role in sensory transduction in the inner ear, especially in the vestibular system. Included in the series of interrelated striated elements are the cuticular plate and its basal attachments to the hair cell margins, the connections of the strut array of the kinociliary basal body to the cuticular plate, and striated organelles associated with the plasma membrane and extending below the apical junctional complexes.

Psychophysical Map Stability in Bilateral Sequential Cochlear Implantation: Comparing Current Audiology Methods to a New Statistical Definition.

PubMed

Domville-Lewis, Chloe; Santa Maria, Peter L; Upson, Gemma; Chester-Browne, Ronel; Atlas, Marcus D

2015-01-01

The purpose of this study was to establish a statistical definition for stability in cochlear implant maps. Once defined, this study aimed to compare the duration taken to achieve a stable map in first and second implants in patients who underwent sequential bilateral cochlear implantation. This article also sought to evaluate a number of factors that potentially affect map stability. A retrospective cohort study of 33 patients with sensorineural hearing loss who received sequential bilateral cochlear implantation (Cochlear, Sydney, Australia), performed by the senior author. Psychophysical parameters of hearing threshold scores, comfort scores, and the dynamic range were measured for the apical, medial, and basal portions of the cochlear implant electrode at a range of intervals postimplantation. Stability was defined statistically as a less than 10% difference in threshold, comfort, and dynamic range scores over three consecutive mapping sessions. A senior cochlear implant audiologist, blinded to implant order and the statistical results, separately analyzed these psychophysical map parameters using current assessment methods. First and second implants were compared for duration to achieve stability, age, gender, the duration of deafness, etiology of deafness, time between the insertion of the first and second implant, and the presence or absence of preoperative hearing aids were evaluated and its relationship to stability. Statistical analysis included performing a two-tailed Student's t tests and least squares regression analysis, with a statistical significance set at p ≤ 0.05. There was a significant positive correlation between the devised statistical definition and the current audiology methods for assessing stability, with a Pearson correlation coefficient r = 0.36 and a least squares regression slope (b) of 0.41, df(58), 95% confidence interval 0.07 to 0.55 (p = 0.004). The average duration from device switch on to stability in the first implant was 87 days using current audiology methods and 81 days using the statistical definition, with no statistically significant difference between assessment methods (p = 0.2). The duration to achieve stability in the second implant was 51 days using current audiology methods and 60 days using the statistical method, and again no difference between the two assessment methods (p = 0.13). There was a significant reduction in the time to achieve stability in second implants for both audiology and statistical methods (p < 0.001 and p = 0.02, respectively). There was a difference in duration to achieve stability based on electrode array region, with basal portions taking longer to stabilize than apical in the first implant (p = 0.02) and both apical and medial segments in second implants (p = 0.004 and p = 0.01, respectively). No factors that were evaluated in this study, including gender, age, etiology of deafness, duration of deafness, time between implant insertion, and the preoperative hearing aid status, were correlated with stability duration in either stability assessment method. Our statistical definition can accurately predict cochlear implant map stability when compared with current audiology practices. Cochlear implants that are implanted second tend to stabilize sooner than the first, which has a significant impact on counseling before a second implant. No factors evaluated affected the duration required to achieve stability in this study.

Auditory Performance and Electrical Stimulation Measures in Cochlear Implant Recipients With Auditory Neuropathy Compared With Severe to Profound Sensorineural Hearing Loss.

PubMed

Attias, Joseph; Greenstein, Tally; Peled, Miriam; Ulanovski, David; Wohlgelernter, Jay; Raveh, Eyal

The aim of the study was to compare auditory and speech outcomes and electrical parameters on average 8 years after cochlear implantation between children with isolated auditory neuropathy (AN) and children with sensorineural hearing loss (SNHL). The study was conducted at a tertiary, university-affiliated pediatric medical center. The cohort included 16 patients with isolated AN with current age of 5 to 12.2 years who had been using a cochlear implant for at least 3.4 years and 16 control patients with SNHL matched for duration of deafness, age at implantation, type of implant, and unilateral/bilateral implant placement. All participants had had extensive auditory rehabilitation before and after implantation, including the use of conventional hearing aids. Most patients received Cochlear Nucleus devices, and the remainder either Med-El or Advanced Bionics devices. Unaided pure-tone audiograms were evaluated before and after implantation. Implantation outcomes were assessed by auditory and speech recognition tests in quiet and in noise. Data were also collected on the educational setting at 1 year after implantation and at school age. The electrical stimulation measures were evaluated only in the Cochlear Nucleus implant recipients in the two groups. Similar mapping and electrical measurement techniques were used in the two groups. Electrical thresholds, comfortable level, dynamic range, and objective neural response telemetry threshold were measured across the 22-electrode array in each patient. Main outcome measures were between-group differences in the following parameters: (1) Auditory and speech tests. (2) Residual hearing. (3) Electrical stimulation parameters. (4) Correlations of residual hearing at low frequencies with electrical thresholds at the basal, middle, and apical electrodes. The children with isolated AN performed equally well to the children with SNHL on auditory and speech recognition tests in both quiet and noise. More children in the AN group than the SNHL group were attending mainstream educational settings at school age, but the difference was not statistically significant. Significant between-group differences were noted in electrical measurements: the AN group was characterized by a lower current charge to reach subjective electrical thresholds, lower comfortable level and dynamic range, and lower telemetric neural response threshold. Based on pure-tone audiograms, the children with AN also had more residual hearing before and after implantation. Highly positive coefficients were found on correlation analysis between T levels across the basal and midcochlear electrodes and low-frequency acoustic thresholds. Prelingual children with isolated AN who fail to show expected oral and auditory progress after extensive rehabilitation with conventional hearing aids should be considered for cochlear implantation. Children with isolated AN had similar pattern as children with SNHL on auditory performance tests after cochlear implantation. The lower current charge required to evoke subjective and objective electrical thresholds in children with AN compared with children with SNHL may be attributed to the contribution to electrophonic hearing from the remaining neurons and hair cells. In addition, it is also possible that mechanical stimulation of the basilar membrane, as in acoustic stimulation, is added to the electrical stimulation of the cochlear implant.

Consequences of Location-Dependent Organ of Corti Micro-Mechanics

PubMed Central

Liu, Yanju; Gracewski, Sheryl M.; Nam, Jong-Hoon

2015-01-01

The cochlea performs frequency analysis and amplification of sounds. The graded stiffness of the basilar membrane along the cochlear length underlies the frequency-location relationship of the mammalian cochlea. The somatic motility of outer hair cell is central for cochlear amplification. Despite two to three orders of magnitude change in the basilar membrane stiffness, the force capacity of the outer hair cell’s somatic motility, is nearly invariant over the cochlear length. It is puzzling how actuators with a constant force capacity can operate under such a wide stiffness range. We hypothesize that the organ of Corti sets the mechanical conditions so that the outer hair cell’s somatic motility effectively interacts with the media of traveling waves—the basilar membrane and the tectorial membrane. To test this hypothesis, a computational model of the gerbil cochlea was developed that incorporates organ of Corti structural mechanics, cochlear fluid dynamics, and hair cell electro-physiology. The model simulations showed that the micro-mechanical responses of the organ of Corti are different along the cochlear length. For example, the top surface of the organ of Corti vibrated more than the bottom surface at the basal (high frequency) location, but the amplitude ratio was reversed at the apical (low frequency) location. Unlike the basilar membrane stiffness varying by a factor of 1700 along the cochlear length, the stiffness of the organ of Corti complex felt by the outer hair cell remained between 1.5 and 0.4 times the outer hair cell stiffness. The Y-shaped structure in the organ of Corti formed by outer hair cell, Deiters cell and its phalange was the primary determinant of the elastic reactance imposed on the outer hair cells. The stiffness and geometry of the Deiters cell and its phalange affected cochlear amplification differently depending on the location. PMID:26317521

Effects of neuroactive steroids on cochlear hair cell death induced by gentamicin.

PubMed

Nakamagoe, Mariko; Tabuchi, Keiji; Nishimura, Bungo; Hara, Akira

2011-12-11

As neuroactive steroids, sex steroid hormones have non-reproductive effects. We previously reported that 17β-estradiol (βE2) had protective effects against gentamicin (GM) ototoxicity in the cochlea. In the present study, we examined whether the protective action of βE2 on GM ototoxicity is mediated by the estrogen receptor (ER) and whether other estrogens (17α-estradiol (αE2), estrone (E1), and estriol (E3)) and other neuroactive steroids, dehydroepiandrosterone (DHEA) and progesterone (P), have similar protective effects. The basal turn of the organ of Corti was dissected from Sprague-Dawley rats and cultured in a medium containing 100 μM GM for 48h. The effects of βE2 and ICI 182,780, a selective ER antagonist, were examined. In addition, the effects of other estrogens, DHEA and P were tested using this culture system. Loss of outer hair cells induced by GM exposure was compared among groups. βE2 exhibited a protective effect against GM ototoxicity, but its protective effect was antagonized by ICI 182,780. αE2, E1, and E3 also protected hair cells against gentamicin ototoxicity. DHEA showed a protective effect; however, the addition of ICI 182,780 did not affect hair cell loss. P did not have any effect on GM-induced outer hair cell death. The present findings suggest that estrogens and DHEA are protective agents against GM ototoxicity. The results of the ER antagonist study also suggest that the protective action of βE2 is mediated via ER but that of DHEA is not related to its conversion to estrogen and binding to ER. Further studies on neuroactive steroids may lead to new insights regarding cochlear protection. Copyright © 2011 Elsevier Inc. All rights reserved.

Human cochlear hydrodynamics: A high-resolution μCT-based finite element study.

PubMed

De Paolis, Annalisa; Watanabe, Hirobumi; Nelson, Jeremy T; Bikson, Marom; Packer, Mark; Cardoso, Luis

2017-01-04

Measurements of perilymph hydrodynamics in the human cochlea are scarce, being mostly limited to the fluid pressure at the basal or apical turn of the scalae vestibuli and tympani. Indeed, measurements of fluid pressure or volumetric flow rate have only been reported in animal models. In this study we imaged the human ear at 6.7 and 3-µm resolution using µCT scanning to produce highly accurate 3D models of the entire ear and particularly the cochlea scalae. We used a contrast agent to better distinguish soft from hard tissues, including the auditory canal, tympanic membrane, malleus, incus, stapes, ligaments, oval and round window, scalae vestibule and tympani. Using a Computational Fluid Dynamics (CFD) approach and this anatomically correct 3D model of the human cochlea, we examined the pressure and perilymph flow velocity as a function of location, time and frequency within the auditory range. Perimeter, surface, hydraulic diameter, Womersley and Reynolds numbers were computed every 45° of rotation around the central axis of the cochlear spiral. CFD results showed both spatial and temporal pressure gradients along the cochlea. Small Reynolds number and large Womersley values indicate that the perilymph fluid flow at auditory frequencies is laminar and its velocity profile is plug-like. The pressure was found 102-106° out of phase with the fluid flow velocity at the scalae vestibule and tympani, respectively. The average flow velocity was found in the sub-µm/s to nm/s range at 20-100Hz, and below the nm/s range at 1-20kHz. Copyright © 2016 Elsevier Ltd. All rights reserved.

Prickle1 regulates neurite outgrowth of apical spiral ganglion neurons but not hair cell polarity in the murine cochlea

PubMed Central

Kersigo, Jennifer; Wu, Shu; Fritzsch, Bernd; Bassuk, Alexander G.

2017-01-01

In the mammalian organ of Corti (OC), the stereocilia on the apical surface of hair cells (HCs) are uniformly organized in a neural to abneural axis (or medial-laterally). This organization is regulated by planar cell polarity (PCP) signaling. Mutations of PCP genes, such as Vangl2, Dvl1/2, Celsr1, and Fzd3/6, affect the formation of HC orientation to varying degrees. Prickle1 is a PCP signaling gene that belongs to the prickle / espinas / testin family. Prickle1 protein is shown to be asymmetrically localized in the HCs of the OC, and this asymmetric localization is associated with loss of PCP in Smurf mutants, implying that Prickle1 is involved in HC PCP development in the OC. A follow-up study found no PCP polarity defects after loss of Prickle1 (Prickle1-/-) in the cochlea. We show here strong Prickle1 mRNA expression in the spiral ganglion by in situ hybridization and β-Gal staining, and weak expression in the OC by β-Gal staining. Consistent with this limited expression in the OC, cochlear HC PCP is unaffected in either Prickle1C251X/C251X mice or Prickle1f/f; Pax2-cre conditional null mice. Meanwhile, type II afferents of apical spiral ganglion neurons (SGN) innervating outer hair cells (OHC) have unusual neurite growth. In addition, afferents from the apex show unusual collaterals in the cochlear nuclei that overlap with basal turn afferents. Our findings argue against the role of Prickle1 in regulating hair cell polarity in the cochlea. Instead, Prickle1 regulates the polarity-related growth of distal and central processes of apical SGNs. PMID:28837644

No effect of prolonged pulsed high frequency ultrasound imaging of the basilar membrane on cochlear function or hair cell survival found in an initial study.

PubMed

Landry, Thomas G; Bance, Manohar L; Adamson, Robert B; Brown, Jeremy A

2018-06-01

Miniature high frequency ultrasound devices show promise as tools for clinical middle ear and basal cochlea imaging and vibrometry. However, before clinical use it is important to verify that the ultrasound exposure does not damage the cochlea. In this initial study, electrophysiological responses of the cochlea were measured for a range of stimulus frequencies in both ears of anesthetized chinchillas, before and after exposing the organ of Corti region of one ear to pulsed focused ultrasound for 30 min. Measurements were again taken after an 11 day survival period. Cochlear tissue was examined with a confocal microscope for signs of damage to the cochlear hair cells. No significant change in response thresholds due to exposure was found, and no signs of ultrasound-induced tissue damage were observed, although one animal (out of ten) did have a region of extensive tissue damage in the exposed cochlea. However, after further analysis this was concluded to be not likely a result of the ultrasound exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of hypoxia on cochlear blood flow in mice evaluated using Doppler optical microangiography.

PubMed

Dziennis, Suzan; Reif, Roberto; Zhi, Zhongwei; Nuttall, Alfred L; Wang, Ruikang K

2012-10-01

Reduced cochlear blood flow (CoBF) is a main contributor to hearing loss. Studying CoBF has remained a challenge due to the lack of available tools. Doppler optical microangiography (DOMAG), a method to quantify single-vessel absolute blood flow, and laser Doppler flowmetry (LDF), a method for measuring the relative blood flow within a large volume of tissue, were used for determining the changes in CoBF due to systemic hypoxia in mice. DOMAG determined the change in blood flow in the apical turn (AT) with single-vessel resolution, while LDF averaged the change in the blood flow within a large volume of the cochlea (hemisphere with ∼1 to 1.5 mm radius). Hypoxia was induced by decreasing the concentration of oxygen-inspired gas, so that the oxygen saturation was reduced from >95% to ∼80%. DOMAG determined that during hypoxia the blood flow in two areas of the AT near and far from the helicotrema were increased and decreased, respectively. The LDF detected a decrease in blood flow within a larger volume of the cochlea (several turns averaged together). Therefore, the use of DOMAG as a tool for studying cochlear blood flow due to its ability to determine absolute flow values with single-vessel resolution was proposed.

Effects of hypoxia on cochlear blood flow in mice evaluated using Doppler optical microangiography

NASA Astrophysics Data System (ADS)

Dziennis, Suzan; Reif, Roberto; Zhi, Zhongwei; Nuttall, Alfred L.; Wang, Ruikang K.

2012-10-01

Reduced cochlear blood flow (CoBF) is a main contributor to hearing loss. Studying CoBF has remained a challenge due to the lack of available tools. Doppler optical microangiography (DOMAG), a method to quantify single-vessel absolute blood flow, and laser Doppler flowmetry (LDF), a method for measuring the relative blood flow within a large volume of tissue, were used for determining the changes in CoBF due to systemic hypoxia in mice. DOMAG determined the change in blood flow in the apical turn (AT) with single-vessel resolution, while LDF averaged the change in the blood flow within a large volume of the cochlea (hemisphere with ˜1 to 1.5 mm radius). Hypoxia was induced by decreasing the concentration of oxygen-inspired gas, so that the oxygen saturation was reduced from >95% to ˜80%. DOMAG determined that during hypoxia the blood flow in two areas of the AT near and far from the helicotrema were increased and decreased, respectively. The LDF detected a decrease in blood flow within a larger volume of the cochlea (several turns averaged together). Therefore, the use of DOMAG as a tool for studying cochlear blood flow due to its ability to determine absolute flow values with single-vessel resolution was proposed.

Changes in the inner ear structures in cystic fibrosis patients.

PubMed

Pauna, Henrique F; Monsanto, Rafael C; Kurata, Natsuko; Paparella, Michael M; Cureoglu, Sebahattin

2017-01-01

Although prolonged use of antibiotics is very common in cystic fibrosis (CF) patients, no studies have assessed the changes in both cochlear and peripheral vestibular systems in this population. We used human temporal bones to analyze the density of vestibular dark, transitional, and hair cells in specimens from CF patients who were exposed to several types of antibiotics, as compared with specimens from an age-matched control group with no history of ear disease or antibiotic use. Additionally, we analyzed the changes in the elements of the cochlea (hair cells, spiral ganglion neurons, and the area of the stria vascularis). Data was gathered using differential interference contrast microscopy and light microscopy. In the CF group, 83% of patients were exposed to some ototoxic drugs, such as aminoglycosides. As compared with the control group, the density of both type I and type II vestibular hair cells was significantly lower in all structures analyzed; the number of dark cells was significantly lower in the lateral and posterior semicircular canals. We noted a trend toward a lower number of both inner and outer cochlear hair cells at all turns of the cochlea. The number of spiral ganglion neurons in Rosenthal's canal at the apical turn of the cochlea was significantly lower; furthermore, the area of the stria vascularis at the apical turn of the cochlea was significantly smaller. Deterioration of cochlear and vestibular structures in CF patients might be related to their exposure to ototoxic antibiotics. Well-designed case-control studies are necessary to rule out the effect of CF itself. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Changes in the Inner Ear Structures in Cystic Fibrosis Patients

PubMed Central

Pauna, Henrique F.; Monsanto, Rafael C.; Kurata, Natsuko; Paparella, Michael M.; Cureoglu, Sebahattin

2016-01-01

Objective Although prolonged use of antibiotics is very common in cystic fibrosis (CF) patients, no studies have assessed the changes in both cochlear and peripheral vestibular systems in this population. Methods We used human temporal bones to analyze the density of vestibular dark, transitional, and hair cells in specimens from CF patients who were exposed to several types of antibiotics, as compared with specimens from an age-matched control group with no history of ear disease or antibiotic use. Additionally, we analyzed the changes in the elements of the cochlea (hair cells, spiral ganglion neurons, and the area of the stria vascularis). Data was gathered using differential interference contrast microscopy and light microscopy. Results In the CF group, 83% of patients were exposed to some ototoxic drugs, such as aminoglycosides. As compared with the control group, the density of both type I and type II vestibular hair cells was significantly lower in all structures analyzed; the number of dark cells was significantly lower in the lateral and posterior semicircular canals. We noted a trend toward a lower number of both inner and outer cochlear hair cells at all turns of the cochlea. The number of spiral ganglion neurons in Rosenthal’s canal at the apical turn of the cochlea was significantly lower; furthermore, the area of the stria vascularis at the apical turn of the cochlea was significantly smaller. Conclusions Deterioration of cochlear and vestibular structures in CF patients might be related to their exposure to ototoxic antibiotics. Well-designed case-control studies are necessary to rule out the effect of CF itself. PMID:28012509

Regional up-regulation of NOX2 contributes to the differential vulnerability of outer hair cells to neomycin.

PubMed

Qi, Meihao; Qiu, Yang; Zhou, Xueying; Tian, Keyong; Zhou, Ke; Sun, Fei; Yue, Bo; Chen, Fuquan; Zha, Dingjun; Qiu, Jianhua

2018-06-02

In hearing loss induced by aminoglycoside antibiotics, the outer hair cells (OHCs) in the basal turn are always more susceptible than OHCs in the apical turn, while the underlying mechanisms remain unknown. In this study, we reported that NAPDH oxidase 2 (NOX2) played an important role in the OHCs damage preferentially in the basal turn. Normally, NOX2 was evenly expressed in OHCs among different turns, at a relatively low level. However, after neomycin treatment, NOX2 was dominantly induced in OHCs in the basal turn. In vivo and in vitro studies demonstrated that inhibition of NOX2 significantly alleviated neomycin-induced OHCs damages, as seen from both the cleaved caspase-3 and TUNEL staining. Moreover, gp91 ds-tat delivery and DHE staining results showed that NOX2-derived ROS was responsible for neomycin ototoxicity. Taken together, our study shows that regional up-expression of NOX2 and subsequent increase of ROS in OHCs of the basal turn is an important factor contributing to the vulnerability of OHCs there, which should shed light on the prevention of hearing loss induced by aminoglycoside antibiotics. Copyright © 2018 Elsevier Inc. All rights reserved.

Persistence, Distribution, and Impact of Distinctly Segmented Microparticles on Cochlear Health following In Vivo Infusion3*

PubMed Central

Ross, Astin M.; Rahmani, Sahar; Prieskorn, Diane M.; Dishman, Acacia F; Miller, Josef M.; Lahann, Joerg; Altschuler, Richard A.

2016-01-01

Delivery of pharmaceuticals to the cochleae of patients with auditory dysfunction could potentially have many benefits from enhancing auditory nerve survival to protecting remaining sensory cells and their neuronal connections. Treatment would require platforms to enable drug delivery directly to the cochlea and increase the potential efficacy of intervention. Cochlear implant recipients are a specific patient subset that could benefit from local drug delivery as more candidates have residual hearing; and since residual hearing directly contributes to post-implantation hearing outcomes, it requires protection from implant insertion-induced trauma. This study assessed the feasibility of utilizing microparticles for drug delivery into cochlear fluids, testing persistence, distribution, biocompatibility, and drug release characteristics. To allow for delivery of multiple therapeutics, particles were composed of two distinct compartments; one containing polylactide-co-glycolide (PLGA), and one composed of acetal-modified dextran and PLGA. Following in vivo infusion, image analysis revealed microparticle persistence in the cochlea for at least 7 days post-infusion, primarily in the first and second turns. The majority of subjects maintained or had only slight elevation in auditory brainstem response thresholds at 7 days post-infusion compared to pre-infusion baselines. There was only minor to limited loss of cochlear hair cells and negligible immune response based on CD45+ immunolabling. When Piribedil-loaded microparticles were infused, Piribedil was detectable within the cochlear fluids at 7 days post-infusion. These results indicate that segmented microparticles are relatively inert, can persist, release their contents, and be functionally and biologically compatible with cochlear function and therefore are promising vehicles for cochlear drug delivery. PMID:26841263

Spatiotemporal loss of K+ transport proteins in the developing cochlear lateral wall of guinea pigs with hereditary deafness.

PubMed

Jin, Zhe; Ulfendahl, Mats; Järlebark, Leif

2008-01-01

Genetic deafness is one of the most common human genetic birth defects. To understand the molecular mechanisms underlying human hereditary deafness, deaf animal strains have proved to be invaluable models. The German waltzing guinea pig is a new strain of animals with unidentified gene mutation(s), displaying recessively inherited cochleovestibular impairment. Histological investigations of the homozygous animals (gw/gw) revealed a collapse of the endolymphatic compartment and malformation of stria vascularis. RT-PCR showed a significant reduction in expression of the strial intermediate cell-specific gene Dct and the tight-junction gene Cldn11 in the embryonic day (E)40 and adult gw/gw cochlear lateral wall. Immunohistochemical analysis of the gw/gw cochlea showed loss of the tight junction protein CLDN11 in strial basal cells from E40, loss of the potassium channel subunit KCNJ10 in strial intermediate cells from E50, and loss of the Na-K-Cl cotransporter SLC12A2 in strial marginal cells from E50. In addition, a temporary loss of the gap junction protein GJB2 (connexin 26) between fibrocytes in the spiral ligament of the E50 gw/gw cochlea was observed. The barrier composed of tight junctions between strial basal cells was disrupted in the gw/gw cochlea as indicated by a biotin tracer permeability assay. In conclusion, spatiotemporal loss of K+ transport proteins in the cochlear lateral wall is caused by malformation of the stria vascularis in the developing German waltzing guinea pig inner ear. This new animal strain may serve as a good model for studying human genetic deafness due to disruption of inner ear ion homeostasis.

Intraoperative Cochlear Implant Device Testing Utilizing an Automated Remote System: A Prospective Pilot Study.

PubMed

Lohmann, Amanda R; Carlson, Matthew L; Sladen, Douglas P

2018-03-01

Intraoperative cochlear implant device testing provides valuable information regarding device integrity, electrode position, and may assist with determining initial stimulation settings. Manual intraoperative device testing during cochlear implantation requires the time and expertise of a trained audiologist. The purpose of the current study is to investigate the feasibility of using automated remote intraoperative cochlear implant reverse telemetry testing as an alternative to standard testing. Prospective pilot study evaluating intraoperative remote automated impedance and Automatic Neural Response Telemetry (AutoNRT) testing in 34 consecutive cochlear implant surgeries using the Intraoperative Remote Assistant (Cochlear Nucleus CR120). In all cases, remote intraoperative device testing was performed by trained operating room staff. A comparison was made to the "gold standard" of manual testing by an experienced cochlear implant audiologist. Electrode position and absence of tip fold-over was confirmed using plain film x-ray. Automated remote reverse telemetry testing was successfully completed in all patients. Intraoperative x-ray demonstrated normal electrode position without tip fold-over. Average impedance values were significantly higher using standard testing versus CR120 remote testing (standard mean 10.7 kΩ, SD 1.2 vs. CR120 mean 7.5 kΩ, SD 0.7, p < 0.001). There was strong agreement between standard manual testing and remote automated testing with regard to the presence of open or short circuits along the array. There were, however, two cases in which standard testing identified an open circuit, when CR120 testing showed the circuit to be closed. Neural responses were successfully obtained in all patients using both systems. There was no difference in basal electrode responses (standard mean 195.0 μV, SD 14.10 vs. CR120 194.5 μV, SD 14.23; p = 0.7814); however, more favorable (lower μV amplitude) results were obtained with the remote automated system in the apical 10 electrodes (standard 185.4 μV, SD 11.69 vs. CR120 177.0 μV, SD 11.57; p value < 0.001). These preliminary data demonstrate that intraoperative cochlear implant device testing using a remote automated system is feasible. This system may be useful for cochlear implant programs with limited audiology support or for programs looking to streamline intraoperative device testing protocols. Future studies with larger patient enrollment are required to validate these promising, but preliminary, findings.

Tissue resistivities determine the current flow in the cochlea.

PubMed

Micco, Alan Gerard; Richter, Claus-Peter

2006-10-01

In individuals with severe to profound hearing loss, cochlear implants bypass normal inner ear function by applying electrical current directly into the cochlea, thereby stimulating cochlear nerve fibers. Stimulating discrete populations of spiral ganglion cells in cochlear implant users' ears is similar to the encoding of small acoustic frequency bands in a normal-hearing person's ear. Thus, spiral ganglion cells stimulated by an electrode convey the information contained by a small acoustic frequency band. Problems that refer to the current spread and subsequent nonselective stimulation of spiral ganglion cells in the cochlea are reviewed. Cochlear anatomy and tissue properties determine the current path in the cochlea. Current spreads largely via scala tympani and across turns. While most of the current leaves the cochlea via the modiolus, the facial canal and the round window constitute additional natural escape paths for the current from the cochlea. Moreover, degenerative processes change tissue resistivities and thus may affect current spread in the cochlea. Electrode design and coding strategies may result in more spatial stimulation of spiral ganglion cells, resulting in a better performance of the electrode-tissue interface.

Sensorineural hearing loss and ischemic injury: Development of animal models to assess vascular and oxidative effects.

PubMed

Olivetto, E; Simoni, E; Guaran, V; Astolfi, L; Martini, A

2015-09-01

Hearing loss may be genetic, associated with aging or exposure to noise or ototoxic substances. Its aetiology can be attributed to vascular injury, trauma, tumours, infections or autoimmune response. All these factors could be related to alterations in cochlear microcirculation resulting in hypoxia, which in turn may damage cochlear hair cells and neurons, leading to deafness. Hypoxia could underlie the aetiology of deafness, but very few data about it are presently available. The aim of this work is to develop animal models of hypoxia and ischemia suitable for study of cochlear vascular damage, characterizing them by electrophysiology and gene/protein expression analyses. The effects of hypoxia in infarction were mimicked in rat by partial permanent occlusion of the left coronary artery, and those of ischemia in thrombosis by complete temporary carotid occlusion. In our models both hypoxia and ischemia caused a small but significant hearing loss, localized at the cochlear apex. A slight induction of the coagulation cascade and of oxidative stress pathways was detected as cell survival mechanism, and cell damages were found on the cuticular plate of outer hair cells only after carotid ischemia. Based on these data, the two developed models appear suitable for in vivo studies of cochlear vascular damage. Copyright © 2015 Elsevier B.V. All rights reserved.

Pharmacokinetic Properties of Adenosine Amine Congener in Cochlear Perilymph after Systemic Administration.

PubMed

Chang, Hao; Telang, Ravindra S; Sreebhavan, Sreevalsan; Tingle, Malcolm; Thorne, Peter R; Vlajkovic, Srdjan M

2017-01-01

Noise-induced hearing loss (NIHL) is a global health problem affecting over 5% of the population worldwide. We have shown previously that acute noise-induced cochlear injury can be ameliorated by administration of drugs acting on adenosine receptors in the inner ear, and a selective A 1 adenosine receptor agonist adenosine amine congener (ADAC) has emerged as a potentially effective treatment for cochlear injury and resulting hearing loss. This study investigated pharmacokinetic properties of ADAC in rat perilymph after systemic (intravenous) administration using a newly developed liquid chromatography-tandem mass spectrometry detection method. The method was developed and validated in accordance with the USA FDA guidelines including accuracy, precision, specificity, and linearity. Perilymph was sampled from the apical turn of the cochlea to prevent contamination with the cerebrospinal fluid. ADAC was detected in cochlear perilymph within two minutes following intravenous administration and remained in perilymph above its minimal effective concentration for at least two hours. The pharmacokinetic pattern of ADAC was significantly altered by exposure to noise, suggesting transient changes in permeability of the blood-labyrinth barrier and/or cochlear blood flow. This study supports ADAC development as a potential clinical otological treatment for acute sensorineural hearing loss caused by exposure to traumatic noise.

Pharmacokinetic Properties of Adenosine Amine Congener in Cochlear Perilymph after Systemic Administration

PubMed Central

Sreebhavan, Sreevalsan; Thorne, Peter R.

2017-01-01

Noise-induced hearing loss (NIHL) is a global health problem affecting over 5% of the population worldwide. We have shown previously that acute noise-induced cochlear injury can be ameliorated by administration of drugs acting on adenosine receptors in the inner ear, and a selective A1 adenosine receptor agonist adenosine amine congener (ADAC) has emerged as a potentially effective treatment for cochlear injury and resulting hearing loss. This study investigated pharmacokinetic properties of ADAC in rat perilymph after systemic (intravenous) administration using a newly developed liquid chromatography-tandem mass spectrometry detection method. The method was developed and validated in accordance with the USA FDA guidelines including accuracy, precision, specificity, and linearity. Perilymph was sampled from the apical turn of the cochlea to prevent contamination with the cerebrospinal fluid. ADAC was detected in cochlear perilymph within two minutes following intravenous administration and remained in perilymph above its minimal effective concentration for at least two hours. The pharmacokinetic pattern of ADAC was significantly altered by exposure to noise, suggesting transient changes in permeability of the blood-labyrinth barrier and/or cochlear blood flow. This study supports ADAC development as a potential clinical otological treatment for acute sensorineural hearing loss caused by exposure to traumatic noise. PMID:28194422

Distortion-product otoacoustic emission reflection-component delays and cochlear tuning: estimates from across the human lifespan.

PubMed

Abdala, Carolina; Guérit, François; Luo, Ping; Shera, Christopher A

2014-04-01

A consistent relationship between reflection-emission delay and cochlear tuning has been demonstrated in a variety of mammalian species, as predicted by filter theory and models of otoacoustic emission (OAE) generation. As a step toward the goal of studying cochlear tuning throughout the human lifespan, this paper exploits the relationship and explores two strategies for estimating delay trends-energy weighting and peak picking-both of which emphasize data at the peaks of the magnitude fine structure. Distortion product otoacoustic emissions (DPOAEs) at 2f1-f2 were recorded, and their reflection components were extracted in 184 subjects ranging in age from prematurely born neonates to elderly adults. DPOAEs were measured from 0.5-4 kHz in all age groups and extended to 8 kHz in young adults. Delay trends were effectively estimated using either energy weighting or peak picking, with the former method yielding slightly shorter delays and the latter somewhat smaller confidence intervals. Delay and tuning estimates from young adults roughly match those obtained from SFOAEs. Although the match is imperfect, reflection-component delays showed the expected bend (apical-basal transition) near 1 kHz, consistent with a break in cochlear scaling. Consistent with other measures of tuning, the term newborn group showed the longest delays and sharpest tuning over much of the frequency range.

Pituitary adenylyl cyclase-activating polypeptide (PACAP) and its receptor (PAC1-R) are positioned to modulate afferent signaling in the cochlea.

PubMed

Drescher, M J; Drescher, D G; Khan, K M; Hatfield, J S; Ramakrishnan, N A; Abu-Hamdan, M D; Lemonnier, L A

2006-09-29

Pituitary adenylyl cyclase-activating polypeptide (PACAP), via its specific receptor pituitary adenylyl cyclase-activating polypeptide receptor 1 (PAC1-R), is known to have roles in neuromodulation and neuroprotection associated with glutamatergic and cholinergic neurotransmission, which, respectively, are believed to form the primary basis for afferent and efferent signaling in the organ of Corti. Previously, we identified transcripts for PACAP preprotein and multiple splice variants of its receptor, PAC1-R, in microdissected cochlear subfractions. In the present work, neural localizations of PACAP and PAC1-R within the organ of Corti and spiral ganglion were examined, defining sites of PACAP action. Immunolocalization of PACAP and PAC1-R in the organ of Corti and spiral ganglion was compared with immunolocalization of choline acetyltransferase (ChAT) and synaptophysin as efferent neuronal markers, and glutamate receptor 2/3 (GluR2/3) and neurofilament 200 as afferent neuronal markers, for each of the three cochlear turns. Brightfield microscopy giving morphological detail for individual immunolocalizations was followed by immunofluorescence detection of co-localizations. PACAP was found to be co-localized with ChAT in nerve fibers of the intraganglionic spiral bundle and beneath the inner and outer hair cells within the organ of Corti. Further, evidence was obtained that PACAP is expressed in type I afferent axons leaving the spiral ganglion en route to the auditory nerve, potentially serving as a neuromodulator in axonal terminals. In contrast to the efferent localization of PACAP within the organ of Corti, PAC1-R immunoreactivity was co-localized with afferent dendritic neuronal marker GluR2/3 in nerve fibers passing beneath and lateral to the inner hair cell and in fibers at supranuclear and basal sites on outer hair cells. Given the known association of PACAP with catecholaminergic neurotransmission in sympathoadrenal function, we also re-examined the issue of whether the organ of Corti receives adrenergic innervation. We now demonstrate the existence of nerve fibers within the organ of Corti which are immunoreactive for the adrenergic marker dopamine beta-hydroxylase (DBH). DBH immunoreactivity was particularly prominent in nerve fibers both at the base and near the cuticular plate of outer hair cells of the apical turn, extending to the non-sensory Hensen's cell region. Evidence was obtained for limited co-localization of DBH with PAC1-R and PACAP. In the process of this investigation, we obtained evidence that efferent and afferent nerve fibers, in addition to adrenergic nerve fibers, are present at supranuclear sites on outer hair cells and distributed within the non-sensory epithelium of the apical cochlear turn for rat, based upon immunoreactivity for the corresponding neuronal markers. Overall, PACAP is hypothesized to act within the organ of Corti as an efferent neuromodulator of afferent signaling via PAC1-R that is present on type I afferent dendrites, in position to afford protection from excitotoxicity. Additionally, PACAP/PAC1-R may modulate secretion of catecholamines from adrenergic terminals within the organ of Corti.

Peer relationships of deaf children with cochlear implants: predictors of peer entry and peer interaction success.

PubMed

Martin, Daniela; Bat-Chava, Yael; Lalwani, Anil; Waltzman, Susan B

2011-01-01

This study investigated factors that affect the development of positive peer relationships among deaf children with cochlear implants. Ten 5- to 6-year-old deaf children with implants were observed under conditions varying peer context difficulty in a Peer Entry task. Results revealed better outcomes for deaf children interacting in one-on-one situations compared to interactions including two other hearing children and better performance among girls than boys. In addition, longer duration of implant use and higher self-esteem were associated with better performance on the Peer Task, which was in turn related to parental reports of children's social functioning outside the experimental situation. These findings contribute to the growing literature describing the benefits of cochlear implantation in the areas of communication and socialization, while pointing to interventions that may enhance deaf children's social competence.

The effect of short-term auditory deprivation on the control of intraoral pressure in pediatric cochlear implant users.

PubMed

Jones, David L; Gao, Sujuan; Svirsky, Mario A

2003-06-01

The purpose of this study was to determine whether 2 speech measures (peak intraoral air pressure [IOP] and IOP duration) obtained during the production of intervocalic stops would be altered as a function of the presence or absence of auditory stimulation provided by a cochlear implant (CI). Five pediatric CI users were required to produce repetitions of the words puppy and baby with their CIs turned on. The CIs were then turned off for 1 hr, at which time the speech sample was repeated with the CI still turned off. Seven children with normal hearing formed a comparison group. They were also tested twice, with a 1-hr intermediate interval. IOP and IOP duration were measured for the medial consonant in both auditory conditions. The results show that auditory condition affected peak IOP more so than IOP duration. Peak IOP was greater for /p/ than /b/ with the CI off, but some participants reduced or reversed this contrast when the CI was on. The findings suggest that different speakers with CIs may use different speech production strategies as they learn to use the auditory signal for speech.

Effect of low-level laser treatment on cochlea hair-cell recovery after ototoxic hearing loss

NASA Astrophysics Data System (ADS)

Rhee, Chung-Ku; He, Peijie; Jung, Jae Yun; Ahn, Jin-Chul; Chung, Phil-Sang; Lee, Min Young; Suh, Myung-Whan

2013-12-01

The primary cause of hearing loss includes damage to cochlear hair cells. Low-level laser therapy (LLLT) has become a popular treatment for damaged nervous systems. Based on the idea that cochlea hair cells and neural cells are from same developmental origin, the effect of LLLT on hearing loss in animal models is evaluated. Hearing loss animal models were established, and the animals were irradiated by 830-nm diode laser once a day for 10 days. Power density of the laser treatment was 900 mW/cm2, and the fluence was 162 to 194 J. The tympanic membrane was evaluated after LLLT. Thresholds of auditory brainstem responses were evaluated before treatment, after gentamicin, and after 10 days of LLLT. Quantitative scanning electron microscopic (SEM) observations were done by counting remaining hair cells. Tympanic membranes were intact at the end of the experiment. No adverse tissue reaction was found. On SEM images, LLLT significantly increased the number of hair cells in middle and basal turns. Hearing was significantly improved by laser irradiation. After LLLT treatment, both the hearing threshold and hair-cell count significantly improved.

Round window electrode insertion potentiates retention in the scala tympani.

PubMed

Connor, Stephen E J; Holland, N Julian; Agger, Andreas; Leong, Annabelle C; Varghese, Re Ajay; Jiang, Dan; Fitzgerald O'Connor, Alec

2012-09-01

The round window membrane (RWM)-intentioned approach is superior to the traditional bony cochleostomy (BC) approach in obtaining electrode placement within the scala tympani (ST). Cochlear implant outcome is influenced by several factors, including optimal placement and retention of the electrode array within the ST. The present study aimed to assess whether the RWM route is superior to a traditional BC for placement and retention of the electrode array in the ST. This was a prospective consecutive non-randomized comparison study. All patients were implanted with the Advanced Bionics 1J electrode array. The RWM approach (n = 32) was compared with a traditional BC group (n = 33). The outcome measure was the electrode position as judged within the scalar chambers at four points along the basal turn using postoperative computed tomography (CT). When the mean position scores were compared, the RWM-intentioned group had significantly more electrodes directed towards the ST compartment than the BC group (p < 0.001). The RWM electrodes achieved 94% ST retention compared with 64% for the BC group (p < 0.05). All electrodes stayed in the ST in the RWM group, whereas in the BC group 9% crossed from the ST to the scala vestibuli.

Electrode spanning with partial tripolar stimulation mode in cochlear implants.

PubMed

Wu, Ching-Chih; Luo, Xin

2014-12-01

The perceptual effects of electrode spanning (i.e., the use of nonadjacent return electrodes) in partial tripolar (pTP) mode were tested on a main electrode EL8 in five cochlear implant (CI) users. Current focusing was controlled by σ (the ratio of current returned within the cochlea), and current steering was controlled by α (the ratio of current returned to the basal electrode). Experiment 1 tested whether asymmetric spanning with α = 0.5 can create additional channels around standard pTP stimuli. It was found that in general, apical spanning (i.e., returning current to EL6 rather than EL7) elicited a pitch between those of standard pTP stimuli on main electrodes EL8 and EL9, while basal spanning (i.e., returning current to EL10 rather than EL9) elicited a pitch between those of standard pTP stimuli on main electrodes EL7 and EL8. The pitch increase caused by apical spanning was more salient than the pitch decrease caused by basal spanning. To replace the standard pTP channel on the main electrode EL8 when EL7 or EL9 is defective, experiment 2 tested asymmetrically spanned pTP stimuli with various α, and experiment 3 tested symmetrically spanned pTP stimuli with various σ. The results showed that pitch increased with decreasing α in asymmetric spanning, or with increasing σ in symmetric spanning. Apical spanning with α around 0.69 and basal spanning with α around 0.38 may both elicit a similar pitch as the standard pTP stimulus. With the same σ, the symmetrically spanned pTP stimulus was higher in pitch than the standard pTP stimulus. A smaller σ was thus required for symmetric spanning to match the pitch of the standard pTP stimulus. In summary, electrode spanning is an effective field-shaping technique that is useful for adding spectral channels and handling defective electrodes with CIs.

The intensity-pitch relation revisited: monopolar versus bipolar cochlear stimulation.

PubMed

Arnoldner, Christoph; Riss, Dominik; Kaider, Alexandra; Mair, Alois; Wagenblast, Jens; Baumgartner, Wolf-Dieter; Gstöttner, Wolfgang; Hamzavi, Jafar-Sasan

2008-09-01

The very high speech perception scores now being achieved with cochlear implants have led to demands for similar levels of achievement in music perception and perception in noisy environments. One of the crucial factors in these fields is pitch perception. The aim of the present study was to investigate the extent to which pitch perception is influenced by the intensity of the stimulus, through the use of different stimulation modes (monopolar, bipolar) and different electrodes (lateral and perimodiolar). Sixteen postlingually deafened patients with an average implant use of 3.1 years were included in this study. All patients were using a Cochlear (CI24M, CI24R, CI24RE) cochlear implant. Subjects were asked to compare the pitch of an intensity-constant reference tone with the pitch of a test tone of varying intensity. The test was repeated for apical, mediocochlear, and basal channel locations, and also for monopolar and bipolar stimulation. It was found that in monopolar stimulation 87.5% and in bipolar stimulation 85.7% of the patients perceived a clear pitch change with changing intensity of the stimulus (Spearman correlation coefficients r < -0.3 or r > 0.3, respectively). A total of 73.1% of these patients perceived lower pitches with increasing intensity, 26.9% reported the opposite effect. No statistically significant difference in the intensity-pitch correlation could be found between mono- and bipolar stimulation. Neither the mean dynamic range nor the type of electrode used was found to be related to the correlation coefficient. Although the majority of today's cochlear implant recipients perform well and the intensity-pitch relation in cochlear implant recipients is still poorly understood, rising demands on speech-coding strategies may soon make a compensation of the pitch shifts desirable. Although the results of our study tend to argue against a peripheral mechanism, the exact origin of this phenomenon remains unclear.

The subcellular distribution of aquaporin 5 in the cochlea reveals a water shunt at the perilymph-endolymph barrier.

PubMed

Hirt, B; Penkova, Z H; Eckhard, A; Liu, W; Rask-Andersen, H; Müller, M; Löwenheim, H

2010-07-28

Aquaporins are membrane water channel proteins that have also been identified in the cochlea. Auditory function critically depends on the homeostasis of the cochlear fluids perilymph and endolymph. In particular, the ion and water regulation of the endolymph is essential for sensory transduction. Within the cochlear duct the lateral wall epithelium has been proposed to secrete endolymph by an aquaporin-mediated flow of water across its epithelial tight junction barrier. This study identifies interspecies differences in the cellular distribution of aquaporin 5 (AQP5) in the cochlear lateral wall of mice, rats, gerbils and guinea pigs. In addition the cellular expression pattern of AQP5 is described in the human cochlea. Developmental changes in rats demonstrate longitudinal and radial gradients along the cochlear duct. During early postnatal development a pancochlear expression is detected. However a regression to the apical quadrant and limitation to outer sulcus cells (OSCs) is observed in the adult. This developmental loss of AQP5 expression in the basal cochlear segments coincides with a morphological loss of contact between OSCs and the endolymph. At the subcellular level, AQP5 exhibits polarized expression in the apical plasma membrane of the OSCs. Complementary, the basolateral membrane in the root processes of the OSCs exhibits AQP4 expression. This differential localization of AQP5 and AQP4 in the apical and basolateral membranes of the same epithelial cell type suggests a direct aquaporin-mediated transcellular water shunt between the perilymph and endolymph in the OSCs of the cochlear lateral wall. In the human cochlea these findings may have pathophysiological implications attributed to a dysfunctional water regulation by AQP5 such as endolymphatic hydrops (i.e. in Meniere's disease) or sensorineural hearing loss (i.e. in Sjögren's syndrome). Copyright (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Channel interaction limits melodic pitch perception in simulated cochlear implants

PubMed Central

Crew, Joseph D.; Galvin, John J.; Fu, Qian-Jie

2012-01-01

In cochlear implants (CIs), melodic pitch perception is limited by the spectral resolution, which in turn is limited by the number of spectral channels as well as interactions between adjacent channels. This study investigated the effect of channel interaction on melodic contour identification (MCI) in normal-hearing subjects listening to novel 16-channel sinewave vocoders that simulated channel interaction in CI signal processing. MCI performance worsened as the degree of channel interaction increased. Although greater numbers of spectral channels may be beneficial to melodic pitch perception, the present data suggest that it is also important to improve independence among spectral channels. PMID:23145706

Micromechanics in the Gerbil Hemicochlea

NASA Astrophysics Data System (ADS)

Richter, C.-P.; Dallos, P.

2003-02-01

Micromechanical events in the cochlea represent the combined motions of all elements that convey vibrations from the basilar membrane (BM) to the stereocilia bundles of the inner hair cells, the sensory receptors of the mammalian cochlea. Because of the difficulty of visualizing the organ of Corti (OC), experimental data on micromechanics are extremely limited. Available results represent motions viewed either from one focal plane or from the surface of a cochlear preparation. The present experiments examine cochlear micromechanics at audio frequencies by using the hemicochlea that permits the viewing of all structures in a cochlear cross-section. Stroboscopic illumination and video-flow techniques have been used to quantify the motion of selected elements. The movements at different locations revealed a tuned response across frequencies with the best frequency increasing from more basal to more apical locations. Furthermore, the vibrations showed rotational components, such as rotations around a pivot point: the inner pillar foot. Inner and outer pillar cells, inner and outer hair cells, Deiters' cells and parts of the BM move together and form a so-called "rotating wedge". The movements of Hensen's cells represent a mode of vibration different from that of the rest of the OC.

Noise Stress Induces an Epidermal Growth Factor Receptor/Xeroderma Pigmentosum-A Response in the Auditory Nerve.

PubMed

Guthrie, O'neil W

2017-03-01

In response to toxic stressors, cancer cells defend themselves by mobilizing one or more epidermal growth factor receptor (EGFR) cascades that employ xeroderma pigmentosum-A (XPA) to repair damaged genes. Recent experiments discovered that neurons within the auditory nerve exhibit basal levels of EGFR+XPA co-expression. This finding implied that auditory neurons in particular or neurons in general have the capacity to mobilize an EGFR+XPA defense. Therefore, the current study tested the hypothesis that noise stress would alter the expression pattern of EGFR/XPA within the auditory nerve. Design-based stereology was used to quantify the proportion of neurons that expressed EGFR, XPA, and EGFR+XPA with and without noise stress. The results revealed an intricate neuronal response that is suggestive of alterations to both co-expression and individual expression of EGFR and XPA. In both the apical and middle cochlear coils, the noise stress depleted EGFR+XPA expression. Furthermore, there was a reduction in the proportion of neurons that expressed XPA-alone in the middle coils. However, the noise stress caused a significant increase in the proportion of neurons that expressed EGFR-alone in the middle coils. The basal cochlear coils failed to mobilize a significant response to the noise stress. These results suggest that EGFR and XPA might be part of the molecular defense repertoire of the auditory nerve.

Noise Stress Induces an Epidermal Growth Factor Receptor/Xeroderma Pigmentosum–A Response in the Auditory Nerve

PubMed Central

Guthrie, O’neil W.

2017-01-01

In response to toxic stressors, cancer cells defend themselves by mobilizing one or more epidermal growth factor receptor (EGFR) cascades that employ xeroderma pigmentosum–A (XPA) to repair damaged genes. Recent experiments discovered that neurons within the auditory nerve exhibit basal levels of EGFR+XPA co-expression. This finding implied that auditory neurons in particular or neurons in general have the capacity to mobilize an EGFR+XPA defense. Therefore, the current study tested the hypothesis that noise stress would alter the expression pattern of EGFR/XPA within the auditory nerve. Design-based stereology was used to quantify the proportion of neurons that expressed EGFR, XPA, and EGFR+XPA with and without noise stress. The results revealed an intricate neuronal response that is suggestive of alterations to both co-expression and individual expression of EGFR and XPA. In both the apical and middle cochlear coils, the noise stress depleted EGFR+XPA expression. Furthermore, there was a reduction in the proportion of neurons that expressed XPA-alone in the middle coils. However, the noise stress caused a significant increase in the proportion of neurons that expressed EGFR-alone in the middle coils. The basal cochlear coils failed to mobilize a significant response to the noise stress. These results suggest that EGFR and XPA might be part of the molecular defense repertoire of the auditory nerve. PMID:28056182

Noise exposure alters cyclooxygenase 1 (COX-1) and 5-lipoxygenase (5-LO) expression in the guinea pig cochlea.

PubMed

Heinrich, Ulf-Rüdiger; Selivanova, Oxana; Schmidtmann, Irene; Feltens, Ralph; Brieger, Jürgen; Mann, Wolf J

2010-03-01

Changes in the metabolism of arachidonic acid (AA) might be part of a noise-induced compensatory mechanism with regional specificity. The released imbalance of prostaglandins and leukotrienes, both AA metabolites, might result in altered blood flow regulation in the inner ear and probably contributes to noise-induced hearing loss. The aim of this study was to gain further information about noise-dependent changes in AA metabolism in the mammalian cochlea. In this prospective animal study, 10 male guinea pigs were exposed to tone bursts for 1 h at 70 dB sound pressure level (SPL) (n = 5) or 90 dB SPL (n = 5). Five animals were used as controls. Alterations in cyclooxygenase 1 (COX-1) and 5-lipoxygenase (5-LO) expression were determined by quantitative immunohistochemical analysis in 11 cochlear regions. COX-1 expression was decreased after both 70 dB SPL and 90 dB SPL exposure in most cell types of the organ of Corti and increased in the nerve fibers of the osseous spiral lamina. 5-LO was lowered after 90 dB SPL exposure, preferentially in the third cochlear turn in the organ of Corti, in the first and second turn in spiral ganglion cells, and in all turns in the stria vascularis.

The potential use of low-frequency tones to locate regions of outer hair cell loss.

PubMed

Kamerer, Aryn M; Diaz, Francisco J; Peppi, Marcello; Chertoff, Mark E

2016-12-01

Current methods used to diagnose cochlear hearing loss are limited in their ability to determine the location and extent of anatomical damage to various cochlear structures. In previous experiments, we have used the electrical potential recorded at the round window -the cochlear response (CR) -to predict the location of damage to outer hair cells in the gerbil. In a follow-up experiment, we applied 10 mM ouabain to the round window niche to reduce neural activity in order to quantify the neural contribution to the CR. We concluded that a significant proportion of the CR to a 762 Hz tone originated from phase-locking activity of basal auditory nerve fibers, which could have contaminated our conclusions regarding outer hair cell health. However, at such high concentrations, ouabain may have also affected the responses from outer hair cells, exaggerating the effect we attributed to the auditory nerve. In this study, we lowered the concentration of ouabain to 1 mM and determined the physiologic effects on outer hair cells using distortion-product otoacoustic emissions. As well as quantifying the effects of 1 mM ouabain on the auditory nerve and outer hair cells, we attempted to reduce the neural contribution to the CR by using near-infrasonic stimulus frequencies of 45 and 85 Hz, and hypothesized that these low-frequency stimuli would generate a cumulative amplitude function (CAF) that could reflect damage to hair cells in the apex more accurately than the 762 stimuli. One hour after application of 1 mM ouabain, CR amplitudes significantly increased, but remained unchanged in the presence of high-pass filtered noise conditions, suggesting that basal auditory nerve fibers have a limited contribution to the CR at such low frequencies. Published by Elsevier B.V.

Current steering with partial tripolar stimulation mode in cochlear implants.

PubMed

Wu, Ching-Chih; Luo, Xin

2013-04-01

The large spread of excitation is a major cause of poor spectral resolution for cochlear implant (CI) users. Partial tripolar (pTP) mode has been proposed to reduce current spread by returning an equally distributed fraction (0.5 × σ) of current to two flanking electrodes and the rest to an extra-cochlear ground. This study tested the efficacy of incorporating current steering into pTP mode to add spectral channels. Different proportions of current [α × σ and (1 - α) × σ] were returned to the basal and apical flanking electrodes respectively to shape the electric field. Loudness and pitch perception with α from 0 to 1 in steps of 0.1 was simulated with a computational model of CI stimulation and tested on the apical, middle, and basal electrodes of six CI subjects. The highest σ allowing for full loudness growth within the implant compliance limit was chosen for each main electrode. Pitch ranking was measured between pairs of loudness-balanced steered pTP stimuli with an α interval of 0.1 at the most comfortable level. Results demonstrated that steered pTP stimuli with α around 0.5 required more current to achieve equal loudness than those with α around 0 or 1, maybe due to more focused excitation patterns. Subjects usually perceived decreasing pitches as α increased from 0 to 1, somewhat consistent with the apical shift of the center of gravity of excitation pattern in the model. Pitch discrimination was not better with α around 0.5 than with α around 0 or 1, except for some subjects and electrodes. For three subjects with better pitch discrimination, about half of the pitch ranges of two adjacent main electrodes overlapped with each other in steered pTP mode. These results suggest that current steering with focused pTP mode may improve spectral resolution and pitch perception with CIs.

The rat cochlea in the absence of circulating adrenal hormones: an electrophysiological and morphological study.

PubMed

Lohuis, P J; Börjesson, P K; Klis, S F; Smoorenburg, G F

2000-05-01

Circulating adrenal hormones affect strial function. Removal of endogenous levels of adrenal steroids by bilateral adrenalectomy (ADX) in rats causes a decrease of Na(+)/K(+)-ATPase activity in the cochlear lateral wall [Rarey et al., 1989. Arch. Otolaryngol. Head Neck Surg. 115, 817-821] and a decrease of the volume of the marginal cells in the stria vascularis [Lohuis et al., 1990. Acta Otolaryngol. (Stockh.) 110, 348-356]. To study further the effect of absence of circulating adrenocorticosteroids on cochlear function, 18 male Long Evans rats underwent either an ADX or a SHAM operation. Electrocochleography was performed 1 week after surgery for tone bursts in a frequency range of 1-16 kHz. Thereafter, the cochleas were harvested and examined histologically. No significant changes in the amplitude growth curves of the summating potential (SP), the compound action potential (CAP) and the cochlear microphonics (CM) were detected after ADX. However, visually, there appeared to be a decrease of endolymphatic volume (tentatively called imdrops). Reissner's membrane (RM) extended less into scala vestibuli in ADX animals than in SHAM-operated animals. The ratio between the length of RM and the straight distance between the medial and lateral attachment points of RM were used as an objective measure to quantify this effect in each sub-apical half turn of the cochlea. The decrease in length of RM was statistically significant. Thus, circulating adrenal hormones appear to be necessary for normal cochlear fluid homeostasis. Absence of one or more of these hormones leads to shrinkage of the scala media (imdrops). However, the absence of adrenal hormones does not affect the gross cochlear potentials. Apparently, the cochlea is capable of compensating for the absence of circulating adrenal hormones to sustain the conditions necessary for proper cochlear transduction.

Type 2 iodothyronine deiodinase expression in the cochlea before the onset of hearing

PubMed Central

Campos-Barros, Angel; Amma, Lori L.; Faris, Jonathan S.; Shailam, Ranu; Kelley, Matthew W.; Forrest, Douglas

2000-01-01

Thyroid hormone signaling during a postnatal period in the mouse is essential for cochlear development and the subsequent onset of hearing. To study the control of this temporal dependency, we investigated the role of iodothyronine deiodinases, which in target tissues convert the prohormone thyroxine into triiodothyronine (T3), the active ligand for the thyroid hormone receptor (TR). Type 2 5′-deiodinase (D2) activity rose dramatically in the mouse cochlea to peak around postnatal day 7 (P7), after which activity declined by P10. This activity peak a few days before the onset of hearing suggests a role for D2 in amplifying local T3 levels at a critical stage of cochlear development. A mouse cochlear D2 cDNA was isolated and demonstrated near identity to rat D2. In situ hybridization localized D2 mRNA in periosteal connective tissue in the modiolus, the cochlear outer capsule and the septal divisions between the turns of the cochlea. Surprisingly, D2 expression in these regions that give rise to the bony labyrinth was complementary to TR expression in the sensory epithelium. Thus, the connective tissue may control deiodination of thyroxine and release of T3 to confer a paracrine-like control of TR activation. These results suggest that temporal and spatial control of ligand availability conferred by D2 provides an unexpectedly important level of regulation of the TR pathways required for cochlear maturation. PMID:10655523

Cochlear compression: perceptual measures and implications for normal and impaired hearing.

PubMed

Oxenham, Andrew J; Bacon, Sid P

2003-10-01

This article provides a review of recent developments in our understanding of how cochlear nonlinearity affects sound perception and how a loss of the nonlinearity associated with cochlear hearing impairment changes the way sounds are perceived. The response of the healthy mammalian basilar membrane (BM) to sound is sharply tuned, highly nonlinear, and compressive. Damage to the outer hair cells (OHCs) results in changes to all three attributes: in the case of total OHC loss, the response of the BM becomes broadly tuned and linear. Many of the differences in auditory perception and performance between normal-hearing and hearing-impaired listeners can be explained in terms of these changes in BM response. Effects that can be accounted for in this way include poorer audiometric thresholds, loudness recruitment, reduced frequency selectivity, and changes in apparent temporal processing. All these effects can influence the ability of hearing-impaired listeners to perceive speech, especially in complex acoustic backgrounds. A number of behavioral methods have been proposed to estimate cochlear nonlinearity in individual listeners. By separating the effects of cochlear nonlinearity from other aspects of hearing impairment, such methods may contribute towards identifying the different physiological mechanisms responsible for hearing loss in individual patients. This in turn may lead to more accurate diagnoses and more effective hearing-aid fitting for individual patients. A remaining challenge is to devise a behavioral measure that is sufficiently accurate and efficient to be used in a clinical setting.

Quantification of solute entry into cochlear perilymph through the round window membrane.

PubMed

Salt, A N; Ma, Y

2001-04-01

The administration of drugs to the inner ear via the round window membrane is becoming more widely used for both clinical and experimental purposes. The actual drug levels achieved in different regions of the inner ear by this method have not been established. The present study has made use of simulations of solute movements in the cochlear fluids to describe the distribution of a marker solute in the guinea pig cochlear fluid spaces. Simulation parameters were derived from experimental measurements using a marker ion, trimethylphenylammonium (TMPA). The distribution of this ion in the cochlea was monitored without volume disturbance using TMPA-selective microelectrodes sealed into the first and second turns of scala tympani (ST). TMPA was applied to perilymph by irrigation of the intact round window membrane with 2 mM solution. At the end of a 90 min application period, TMPA in the first turn, 1.4 mm from the base of ST, reached an average concentration of 330 microM (standard deviation (S.D.) 147 microM, n = 8). TMPA in the second turn, 7.5 mm from the base of ST reached a concentration of 15 microM (S.D. 33 microM, n = 5). The measured time courses of TMPA concentration change were interpreted using the Washington University Cochlear Fluids Simulator (V 1.4), a public-domain program available on the internet at http ://oto.wustl.edu/cochlea/. Simulations with parameters producing concentration time courses comparable to those measured were: (1) round window permeability: 1.9 x 10(-80 cm/s; (2) ST clearance half-time: 60 min; (3) longitudinal perilymph flow rate: 4.4 nl/min, directed from base to apex. Solute concentrations in apical regions of the cochlea were found to be determined primarily by the rate at which the solute diffuses, balanced by the rate of clearance of the solute from perilymph. Longitudinal perilymph flow was not an important factor in solute distribution unless the bony otic capsule was perforated, which rapidly caused substantial changes to solute distribution. This study demonstrates the basic processes by which substances are distributed in the cochlea and provides a foundation to understand how other applied substances will be distributed in the ear.

Modeling OAE responses to short tones

NASA Astrophysics Data System (ADS)

Duifhuis, Hendrikus; Siegel, Jonathan

2015-12-01

In 1999 Shera and Guinan postulated that otoacoustic emissions evoked by low-level transient stimuli are generated by coherent linear reflection (CRF or CLR). This hypothesis was tested experimentally, e.g., by Siegel and Charaziak[10] by measuring emissions evoked by short (1 ms) tone pips in chinchilla. Using techniques in which supplied level and recorded spectral information were used Siegel and Charaziak concluded that much of the emission was generated by a mechanism in a region extending basally from the peak of the traveling wave and that the action of the suppressor is to remove emission generators evoked by the tone-pip and not to generate nonlinear artifacts in regions basal to the peak region. The original formulation of the CRF theory does not account for these results This study addresses relevant cochlear model predictions.

Outer Hair Cell Electromotility in vivo

NASA Astrophysics Data System (ADS)

Ramamoorthy, Sripriya; Nuttall, Alfred L.

2011-11-01

The effectiveness of outer hair cell (OHC) electro-motility in vivo has been challenged by the expected low-pass filtering of the transmembrane potential due to the cell's own capacitance. The OHC electromotility is characterized here by an electromechanical ratio defined as the ratio of the OHC contraction to the transmembrane potential. This ratio has been measured in isolated cells to be approximately 26 nm/mV. We estimate the OHC electromechanical ratio in vivo from the recently measured displacements of the reticular lamina and the basilar membrane near the 19 kHz characteristic frequency in the basal region of guinea pig cochlea. Our analysis strongly suggests OHC electromotility process is effective for cochlear amplification in vivo at least around the characteristic frequency of the basal location in spite of the low-pass filtering.

Audiological follow-up of 24 patients affected by Williams syndrome.

PubMed

Barozzi, Stefania; Soi, Daniela; Spreafico, Emanuela; Borghi, Anna; Comiotto, Elisabetta; Gagliardi, Chiara; Selicorni, Angelo; Forti, Stella; Cesarani, Antonio; Brambilla, Daniele

2013-09-01

Williams syndrome is a neurodevelopmental disorder associated with cardiovascular problems, facial abnormalities and several behavioural and neurological disabilities. It is also characterized by some typical audiological features including abnormal sensitivity to sounds, cochlear impairment related to the outer hair cells of the basal turn of the cochlea, and sensorineural or mixed hearing loss, predominantly in the high frequency range. The aim of this report is to describe a follow-up study of auditory function in a cohort of children affected by this syndrome. 24 patients, aged 5-14 years, were tested by means of air/bone conduction pure-tone audiometry, immittance test and transient evoked otoacoustic emissions. They were evaluated again 5 years after the first assessment, and 10 of them underwent a second follow-up examination after a further 5 years. The audiometric results showed hearing loss, defined by a pure tone average >15 dB HL, in 12.5% of the participants. The incidence of hearing loss did not change over the 5-year period and increased to 30% in the patients who underwent the 10-year follow-up. Progressive sensorineural hearing loss was detected in 20% of the patients. A remarkable finding of our study regarded sensorineural hearing impairment in the high frequency range, which increased significantly from 25% to 50% of the participants over the 5-year period. The increase became even more significant in the group of patients who underwent the 10-year follow-up, by which time the majority of them (80%) had developed sensorineural hearing loss. Otoacoustic emissions were found to be absent in a high percentage of patients, thus confirming the cochlear fragility of individuals with Williams syndrome. Our study verified that most of the young Williams syndrome patients had normal hearing sensitivity within the low-middle frequency range, but showed a weakness regarding the high frequencies, the threshold of which worsened significantly over time in most patients. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Prestin Regulation and Function in Residual Outer Hair Cells after Noise-Induced Hearing Loss

PubMed Central

Xia, Anping; Song, Yohan; Wang, Rosalie; Gao, Simon S.; Clifton, Will; Raphael, Patrick; Chao, Sung-il; Pereira, Fred A.; Groves, Andrew K.; Oghalai, John S.

2013-01-01

The outer hair cell (OHC) motor protein prestin is necessary for electromotility, which drives cochlear amplification and produces exquisitely sharp frequency tuning. TectaC1509G transgenic mice have hearing loss, and surprisingly have increased OHC prestin levels. We hypothesized, therefore, that prestin up-regulation may represent a generalized response to compensate for a state of hearing loss. In the present study, we sought to determine the effects of noise-induced hearing loss on prestin expression. After noise exposure, we performed cytocochleograms and observed OHC loss only in the basal region of the cochlea. Next, we patch clamped OHCs from the apical turn (9–12 kHz region), where no OHCs were lost, in noise-exposed and age-matched control mice. The non-linear capacitance was significantly higher in noise-exposed mice, consistent with higher functional prestin levels. We then measured prestin protein and mRNA levels in whole-cochlea specimens. Both Western blot and qPCR studies demonstrated increased prestin expression after noise exposure. Finally, we examined the effect of the prestin increase in vivo following noise damage. Immediately after noise exposure, ABR and DPOAE thresholds were elevated by 30–40 dB. While most of the temporary threshold shifts recovered within 3 days, there were additional improvements over the next month. However, DPOAE magnitudes, basilar membrane vibration, and CAP tuning curve measurements from the 9–12 kHz cochlear region demonstrated no differences between noise-exposed mice and control mice. Taken together, these data indicate that prestin is up-regulated by 32–58% in residual OHCs after noise exposure and that the prestin is functional. These findings are consistent with the notion that prestin increases in an attempt to partially compensate for reduced force production because of missing OHCs. However, in regions where there is no OHC loss, the cochlea is able to compensate for the excess prestin in order to maintain stable auditory thresholds and frequency discrimination. PMID:24376553

Improvement of the insertion axis for cochlear implantation with a robot-based system.

PubMed

Torres, Renato; Kazmitcheff, Guillaume; De Seta, Daniele; Ferrary, Evelyne; Sterkers, Olivier; Nguyen, Yann

2017-02-01

It has previously reported that alignment of the insertion axis along the basal turn of the cochlea was depending on surgeon' experience. In this experimental study, we assessed technological assistances, such as navigation or a robot-based system, to improve the insertion axis during cochlear implantation. A preoperative cone beam CT and a mastoidectomy with a posterior tympanotomy were performed on four temporal bones. The optimal insertion axis was defined as the closest axis to the scala tympani centerline avoiding the facial nerve. A neuronavigation system, a robot assistance prototype, and software allowing a semi-automated alignment of the robot were used to align an insertion tool with an optimal insertion axis. Four procedures were performed and repeated three times in each temporal bone: manual, manual navigation-assisted, robot-based navigation-assisted, and robot-based semi-automated. The angle between the optimal and the insertion tool axis was measured in the four procedures. The error was 8.3° ± 2.82° for the manual procedure (n = 24), 8.6° ± 2.83° for the manual navigation-assisted procedure (n = 24), 5.4° ± 3.91° for the robot-based navigation-assisted procedure (n = 24), and 3.4° ± 1.56° for the robot-based semi-automated procedure (n = 12). A higher accuracy was observed with the semi-automated robot-based technique than manual and manual navigation-assisted (p < 0.01). Combination of a navigation system and a manual insertion does not improve the alignment accuracy due to the lack of friendly user interface. On the contrary, a semi-automated robot-based system reduces both the error and the variability of the alignment with a defined optimal axis.

Pitch ranking, electrode discrimination, and physiological spread-of-excitation using Cochlear's dual-electrode mode.

PubMed

Goehring, Jenny L; Neff, Donna L; Baudhuin, Jacquelyn L; Hughes, Michelle L

2014-08-01

This study compared pitch ranking, electrode discrimination, and electrically evoked compound action potential (ECAP) spatial excitation patterns for adjacent physical electrodes (PEs) and the corresponding dual electrodes (DEs) for newer-generation Cochlear devices (Cochlear Ltd., Macquarie, New South Wales, Australia). The first goal was to determine whether pitch ranking and electrode discrimination yield similar outcomes for PEs and DEs. The second goal was to determine if the amount of spatial separation among ECAP excitation patterns (separation index, Σ) between adjacent PEs and the PE-DE pairs can predict performance on the psychophysical tasks. Using non-adaptive procedures, 13 subjects completed pitch ranking and electrode discrimination for adjacent PEs and the corresponding PE-DE pairs (DE versus each flanking PE) from the basal, middle, and apical electrode regions. Analysis of d' scores indicated that pitch-ranking and electrode-discrimination scores were not significantly different, but rather produced similar levels of performance. As expected, accuracy was significantly better for the PE-PE comparison than either PE-DE comparison. Correlations of the psychophysical versus ECAP Σ measures were positive; however, not all test/region correlations were significant across the array. Thus, the ECAP separation index is not sensitive enough to predict performance on behavioral tasks of pitch ranking or electrode discrimination for adjacent PEs or corresponding DEs.

Rate discrimination at low pulse rates in normal-hearing and cochlear implant listeners: Influence of intracochlear stimulation site.

PubMed

Stahl, Pierre; Macherey, Olivier; Meunier, Sabine; Roman, Stéphane

2016-04-01

Temporal pitch perception in cochlear implantees remains weaker than in normal hearing listeners and is usually limited to rates below about 300 pulses per second (pps). Recent studies have suggested that stimulating the apical part of the cochlea may improve the temporal coding of pitch by cochlear implants (CIs), compared to stimulating other sites. The present study focuses on rate discrimination at low pulse rates (ranging from 20 to 104 pps). Two experiments measured and compared pulse rate difference limens (DLs) at four fundamental frequencies (ranging from 20 to 104 Hz) in both CI and normal-hearing (NH) listeners. Experiment 1 measured DLs in users of the (Med-El CI, Innsbruck, Austria) device for two electrodes (one apical and one basal). In experiment 2, DLs for NH listeners were compared for unresolved harmonic complex tones filtered in two frequency regions (lower cut-off frequencies of 1200 and 3600 Hz, respectively) and for different bandwidths. Pulse rate discrimination performance was significantly better when stimulation was provided by the apical electrode in CI users and by the lower-frequency tone complexes in NH listeners. This set of data appears consistent with better temporal coding when stimulation originates from apical regions of the cochlea.

Pitch ranking, electrode discrimination, and physiological spread-of-excitation using Cochlear's dual-electrode mode

PubMed Central

Goehring, Jenny L.; Neff, Donna L.; Baudhuin, Jacquelyn L.; Hughes, Michelle L.

2014-01-01

This study compared pitch ranking, electrode discrimination, and electrically evoked compound action potential (ECAP) spatial excitation patterns for adjacent physical electrodes (PEs) and the corresponding dual electrodes (DEs) for newer-generation Cochlear devices (Cochlear Ltd., Macquarie, New South Wales, Australia). The first goal was to determine whether pitch ranking and electrode discrimination yield similar outcomes for PEs and DEs. The second goal was to determine if the amount of spatial separation among ECAP excitation patterns (separation index, Σ) between adjacent PEs and the PE-DE pairs can predict performance on the psychophysical tasks. Using non-adaptive procedures, 13 subjects completed pitch ranking and electrode discrimination for adjacent PEs and the corresponding PE-DE pairs (DE versus each flanking PE) from the basal, middle, and apical electrode regions. Analysis of d′ scores indicated that pitch-ranking and electrode-discrimination scores were not significantly different, but rather produced similar levels of performance. As expected, accuracy was significantly better for the PE-PE comparison than either PE-DE comparison. Correlations of the psychophysical versus ECAP Σ measures were positive; however, not all test/region correlations were significant across the array. Thus, the ECAP separation index is not sensitive enough to predict performance on behavioral tasks of pitch ranking or electrode discrimination for adjacent PEs or corresponding DEs. PMID:25096106

Single-unit labeling of medial olivocochlear neurons: the cochlear frequency map for efferent axons.

PubMed

Brown, M Christian

2014-06-01

Medial olivocochlear (MOC) neurons are efferent neurons that project axons from the brain to the cochlea. Their action on outer hair cells reduces the gain of the "cochlear amplifier," which shifts the dynamic range of hearing and reduces the effects of noise masking. The MOC effects in one ear can be elicited by sound in that ipsilateral ear or by sound in the contralateral ear. To study how MOC neurons project onto the cochlea to mediate these effects, single-unit labeling in guinea pigs was used to study the mapping of MOC neurons for neurons responsive to ipsilateral sound vs. those responsive to contralateral sound. MOC neurons were sharply tuned to sound frequency with a well-defined characteristic frequency (CF). However, their labeled termination spans in the organ of Corti ranged from narrow to broad, innervating between 14 and 69 outer hair cells per axon in a "patchy" pattern. For units responsive to ipsilateral sound, the midpoint of innervation was mapped according to CF in a relationship generally similar to, but with more variability than, that of auditory-nerve fibers. Thus, based on CF mappings, most of the MOC terminations miss outer hair cells involved in the cochlear amplifier for their CF, which are located more basally. Compared with ipsilaterally responsive neurons, contralaterally responsive neurons had an apical offset in termination and a larger span of innervation (an average of 10.41% cochlear distance), suggesting that when contralateral sound activates the MOC reflex, the actions are different than those for ipsilateral sound. Copyright © 2014 the American Physiological Society.

Single-unit labeling of medial olivocochlear neurons: the cochlear frequency map for efferent axons

PubMed Central

2014-01-01

Medial olivocochlear (MOC) neurons are efferent neurons that project axons from the brain to the cochlea. Their action on outer hair cells reduces the gain of the “cochlear amplifier,” which shifts the dynamic range of hearing and reduces the effects of noise masking. The MOC effects in one ear can be elicited by sound in that ipsilateral ear or by sound in the contralateral ear. To study how MOC neurons project onto the cochlea to mediate these effects, single-unit labeling in guinea pigs was used to study the mapping of MOC neurons for neurons responsive to ipsilateral sound vs. those responsive to contralateral sound. MOC neurons were sharply tuned to sound frequency with a well-defined characteristic frequency (CF). However, their labeled termination spans in the organ of Corti ranged from narrow to broad, innervating between 14 and 69 outer hair cells per axon in a “patchy” pattern. For units responsive to ipsilateral sound, the midpoint of innervation was mapped according to CF in a relationship generally similar to, but with more variability than, that of auditory-nerve fibers. Thus, based on CF mappings, most of the MOC terminations miss outer hair cells involved in the cochlear amplifier for their CF, which are located more basally. Compared with ipsilaterally responsive neurons, contralaterally responsive neurons had an apical offset in termination and a larger span of innervation (an average of 10.41% cochlear distance), suggesting that when contralateral sound activates the MOC reflex, the actions are different than those for ipsilateral sound. PMID:24598524

Measurement of in vivo basal-turn vibrations of the organ of Corti using phase-sensitive Fourier domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Ramamoorthy, Sripriya; Zhang, Yuan; Petrie, Tracy; Chen, Fangyi; Subhash, Hrebesh M.; Choudhury, Niloy; Wang, Ruikang; Jacques, Steven L.; Nuttall, Alfred L.

2013-03-01

A major reason we can perceive faint sounds and communicate in noisy environments is that the outer hair cells of the organ of Corti enhance the sound-evoked motions inside the cochlea. To understand how the organ of Corti works, we have built and tested the phase-sensitive Fourier domain optical coherence tomography (PSFDOCT) system. This system has key advantages over our previous time domain OCT system [1]. The PSFDOCT system has better signal to noise and simultaneously acquires vibration data from all points along the optical-axis [2]. Feasibility of this system to measure in vitro cochlear vibrations in the apex was demonstrated earlier [3]. In this study, we measure the in vivo vibrations of the organ of Corti via round window in live anaesthetized guinea pigs using PSFDOCT. This region of the guinea pig cochlea responds to very high frequencies (10 - 40 kHz). The current vibration noise floor for native organ of Corti tissue is 0.03 nm in this frequency range. Sound-induced vibrations of the stapes, which delivers input to the cochlea, are also measured. The measured vibrations of the organ of Corti demonstrate non-linear compression and active amplification characteristic of sensitive mammalian cochlea.

Internalized elevation perception of simple stimuli in cochlear-implant and normal-hearing listeners

PubMed Central

Thakkar, Tanvi; Goupell, Matthew J.

2014-01-01

In normal-hearing (NH) listeners, elevation perception is produced by the spectral cues imposed by the pinna, head, and torso. Elevation perception in cochlear-implant (CI) listeners appears to be non-existent; this may be a result of poorly encoded spectral cues. In this study, an analog of elevation perception was investigated by having 15 CI and 8 NH listeners report the intracranial location of spectrally simple signals (single-electrode or bandlimited acoustic stimuli, respectively) in both horizontal and vertical dimensions. Thirteen CI listeners and all of the NH listeners showed an association between place of stimulation (i.e., stimulus frequency) and perceived elevation, generally responding with higher elevations for more basal stimulation. This association persisted in the presence of a randomized temporal pitch, suggesting that listeners were not associating pitch with elevation. These data provide evidence that CI listeners might perceive changes in elevation if they were presented stimuli with sufficiently salient elevation cues. PMID:25096117

Speech production in experienced cochlear implant users undergoing short-term auditory deprivation

NASA Astrophysics Data System (ADS)

Greenman, Geoffrey; Tjaden, Kris; Kozak, Alexa T.

2005-09-01

This study examined the effect of short-term auditory deprivation on the speech production of five postlingually deafened women, all of whom were experienced cochlear implant users. Each cochlear implant user, as well as age and gender matched control speakers, produced CVC target words embedded in a reading passage. Speech samples for the deafened adults were collected on two separate occasions. First, the speakers were recorded after wearing their speech processor consistently for at least two to three hours prior to recording (implant ``ON''). The second recording occurred when the speakers had their speech processors turned off for approximately ten to twelve hours prior to recording (implant ``OFF''). Acoustic measures, including fundamental frequency (F0), the first (F1) and second (F2) formants of the vowels, vowel space area, vowel duration, spectral moments of the consonants, as well as utterance duration and sound pressure level (SPL) across the entire utterance were analyzed in both speaking conditions. For each implant speaker, acoustic measures will be compared across implant ``ON'' and implant ``OFF'' speaking conditions, and will also be compared to data obtained from normal hearing speakers.

Malformation of stria vascularis in the developing inner ear of the German waltzing guinea pig.

PubMed

Jin, Zhe; Mannström, Paula; Järlebark, Leif; Ulfendahl, Mats

2007-05-01

Auditory function and cochlear morphology have previously been described in the postnatal German waltzing guinea pig, a strain with recessive deafness. In the present study, cochlear histopathology was further investigated in the inner ear of the developing German waltzing guinea pig (gw/gw). The lumen of the cochlear duct diminished progressively from embryonic day (E) 35 to E45 and was absent at E50 because of the complete collapse of Reissner's membrane onto the hearing organ. The embryonic stria vascularis, consisting of a simple epithelium, failed to transform into the complex trilaminar tissue seen in normal animals and displayed signs of degeneration. Subsequent degeneration of the sensory epithelium was observed from E50 and onwards. Defective and insufficient numbers of melanocytes were observed in the developing gw/gw stria vascularis. A gene involved in cochlear melanocyte development, Pax3, was markedly reduced in lateral wall tissue of the cochlea of both E40 and adult gw/gw individuals, whereas its expression was normal in the skin and diaphragm muscle of adult gw/gw animals. The Pax3 gene may thus be involved in the pathological process but is unlikely to be the primary mutated gene in the German waltzing guinea pig. TUNEL assay showed no signs of apoptotic cell death in the developing stria vascularis of this type of guinea pig. Thus, malformation of the stria vascularis appears to be the primary defect in the inner ear of the German waltzing guinea pig. Defective and insufficient numbers of melanocytes might migrate to the developing stria vascularis but fail to provide the proper support for the subsequent development of marginal and basal cells, thereby leading to stria vascularis malformation and dysfunction in the inner ear of the German waltzing guinea pig.

Origin and function of short-latency inputs to the neural substrates underlying the acoustic startle reflex

PubMed Central

Gómez-Nieto, Ricardo; Horta-Júnior, José de Anchieta C.; Castellano, Orlando; Millian-Morell, Lymarie; Rubio, Maria E.; López, Dolores E.

2014-01-01

The acoustic startle reflex (ASR) is a survival mechanism of alarm, which rapidly alerts the organism to a sudden loud auditory stimulus. In rats, the primary ASR circuit encompasses three serially connected structures: cochlear root neurons (CRNs), neurons in the caudal pontine reticular nucleus (PnC), and motoneurons in the medulla and spinal cord. It is well-established that both CRNs and PnC neurons receive short-latency auditory inputs to mediate the ASR. Here, we investigated the anatomical origin and functional role of these inputs using a multidisciplinary approach that combines morphological, electrophysiological and behavioral techniques. Anterograde tracer injections into the cochlea suggest that CRNs somata and dendrites receive inputs depending, respectively, on their basal or apical cochlear origin. Confocal colocalization experiments demonstrated that these cochlear inputs are immunopositive for the vesicular glutamate transporter 1 (VGLUT1). Using extracellular recordings in vivo followed by subsequent tracer injections, we investigated the response of PnC neurons after contra-, ipsi-, and bilateral acoustic stimulation and identified the source of their auditory afferents. Our results showed that the binaural firing rate of PnC neurons was higher than the monaural, exhibiting higher spike discharges with contralateral than ipsilateral acoustic stimulations. Our histological analysis confirmed the CRNs as the principal source of short-latency acoustic inputs, and indicated that other areas of the cochlear nucleus complex are not likely to innervate PnC. Behaviorally, we observed a strong reduction of ASR amplitude in monaural earplugged rats that corresponds with the binaural summation process shown in our electrophysiological findings. Our study contributes to understand better the role of neuronal mechanisms in auditory alerting behaviors and provides strong evidence that the CRNs-PnC pathway mediates fast neurotransmission and binaural summation of the ASR. PMID:25120419

Qualities of Single Electrode Stimulation as a Function of Rate and Place of Stimulation with a Cochlear Implant

PubMed Central

Landsberger, David M.; Vermeire, Katrien; Claes, Annes; Van Rompaey, Vincent; Van de Heyning, Paul

2015-01-01

Objectives Although it has been previously shown that changes in temporal coding produce changes in pitch in all cochlear regions, research has suggested that temporal coding might be best encoded in relatively apical locations. We hypothesized that although temporal coding may provide useable information at any cochlear location, low rates of stimulation might provide better sound quality in apical regions that are more likely to encode temporal information in the normal ear. In the present study, sound qualities of single electrode pulse trains were scaled to provide insight into the combined effects of cochlear location and stimulation rate on sound quality. Design Ten long term users of MED-EL cochlear implants with 31 mm electrode arrays (Standard or FLEXSOFT) were asked to scale the sound quality of single electrode pulse trains in terms of how “Clean”, “Noisy”, “High”, and “Annoying” they sounded. Pulse trains were presented on most electrodes between 1 and 12 representing the entire range of the long electrode array at stimulation rates of 100, 150, 200, 400, or 1500 pulses per second. Results While high rates of stimulation are scaled as having a “Clean” sound quality across the entire array, only the most apical electrodes (typically 1 through 3) were considered “Clean” at low rates. Low rates on electrodes 6 through 12 were not rated as “Clean” while the low rate quality of electrodes 4 and 5 were typically in between. Scaling of “Noisy” responses provided an approximately inverse pattern as “Clean” responses. “High” responses show the trade-off between rate and place of stimulation on pitch. Because “High” responses did not correlate with “Clean” responses, subjects were not rating sound quality based on pitch. Conclusions If explicit temporal coding is to be provided in a cochlear implant, it is likely to sound better when provided apically. Additionally, the finding that low rates sound clean only at apical places of stimulation is consistent with previous findings that a change in rate of stimulation corresponds to an equivalent change in perceived pitch at apical locations. Collectively, the data strongly suggests that temporal coding with a cochlear implant is optimally provided by electrodes placed well into the second cochlear turn. PMID:26583480

The Summating Potential Is a Reliable Marker of Electrode Position in Electrocochleography: Cochlear Implant as a Theragnostic Probe.

PubMed

Helmstaedter, Victor; Lenarz, Thomas; Erfurt, Peter; Kral, Andrej; Baumhoff, Peter

2017-12-14

For the increasing number of cochlear implantations in subjects with residual hearing, hearing preservation, and thus the prevention of implantation trauma, is crucial. A method for monitoring the intracochlear position of a cochlear implant (CI) and early indication of imminent cochlear trauma would help to assist the surgeon to achieve this goal. The aim of this study was to evaluate the reliability of the different electric components recorded by an intracochlear electrocochleography (ECochG) as markers for the cochleotopic position of a CI. The measurements were made directly from the CI, combining intrasurgical diagnostics with the therapeutical use of the CI, thus, turning the CI into a "theragnostic probe." Intracochlear ECochGs were measured in 10 Dunkin Hartley guinea pigs of either sex, with normal auditory brainstem response thresholds. All subjects were fully implanted (4 to 5 mm) with a custom six contact CI. The ECochG was recorded simultaneously from all six contacts with monopolar configuration (retroauricular reference electrode). The gross ECochG signal was filtered off-line to separate three of its main components: compound action potential, cochlear microphonic, and summating potential (SP). Additionally, five cochleae were harvested and histologically processed to access the spatial position of the CI contacts. Both ECochG data and histological reconstructions of the electrode position were fitted with the Greenwood function to verify the reliability of the deduced cochleotopic position of the CI. SPs could be used as suitable markers for the frequency position of the recording electrode with an accuracy of ±1/4 octave in the functioning cochlea, verified by histology. Cochlear microphonics showed a dependency on electrode position but were less reliable as positional markers. Compound action potentials were not suitable for CI position information but were sensitive to "cochlear health" (e.g., insertion trauma). SPs directly recorded from the contacts of a CI during surgery can be used to access the intracochlear frequency position of the CI. Using SP monitoring, implantation may be stopped before penetrating functioning cochlear regions. If the technique was similarly effective in humans, it could prevent implantation trauma and increase hearing preservation during CI surgery. Diagnostic hardware and software for recording biological signals with a CI without filter limitations might be a valuable add-on to the portfolios of CI manufacturers.

Hypoxia Induces a Metabolic Shift and Enhances the Stemness and Expansion of Cochlear Spiral Ganglion Stem/Progenitor Cells

PubMed Central

Chao, Ting-Ting; Sytwu, Huey-Kang; Li, Shiue-Li; Fang, Mei-Cho; Chen, Hang-Kang; Lin, Yi-Chun; Kuo, Chao-Yin

2015-01-01

Previously, we demonstrated that hypoxia (1% O2) enhances stemness markers and expands the cell numbers of cochlear stem/progenitor cells (SPCs). In this study, we further investigated the long-term effect of hypoxia on stemness and the bioenergetic status of cochlear spiral ganglion SPCs cultured at low oxygen tensions. Spiral ganglion SPCs were obtained from postnatal day 1 CBA/CaJ mouse pups. The measurement of oxygen consumption rate, extracellular acidification rate (ECAR), and intracellular adenosine triphosphate levels corresponding to 20% and 5% oxygen concentrations was determined using a Seahorse XF extracellular flux analyzer. After low oxygen tension cultivation for 21 days, the mean size of the hypoxia-expanded neurospheres was significantly increased at 5% O2; this correlated with high-level expression of hypoxia-inducible factor-1 alpha (Hif-1α), proliferating cell nuclear antigen (PCNA), cyclin D1, Abcg2, nestin, and Nanog proteins but downregulated expression of p27 compared to that in a normoxic condition. Low oxygen tension cultivation tended to increase the side population fraction, with a significant difference found at 5% O2 compared to that at 20% O2. In addition, hypoxia induced a metabolic energy shift of SPCs toward higher basal ECARs and higher maximum mitochondrial respiratory capacity but lower proton leak than under normoxia, where the SPC metabolism was switched toward glycolysis in long-term hypoxic cultivation. PMID:26236724

Cochlear anatomy using micro computed tomography (μCT) imaging

NASA Astrophysics Data System (ADS)

Kim, Namkeun; Yoon, Yongjin; Steele, Charles; Puria, Sunil

2008-02-01

A novel micro computed tomography (μCT) image processing method was implemented to measure anatomical features of the gerbil and chinchilla cochleas, taking into account the bent modailosis axis. Measurements were made of the scala vestibule (SV) area, the scala tympani (SV) area, and the basilar membrane (BM) width using prepared cadaveric temporal bones. 3-D cochlear structures were obtained from the scanned images using a process described in this study. It was necessary to consider the sharp curvature of mododailosis axis near the basal region. The SV and ST areas were calculated from the μCT reconstructions and compared with existing data obtained by Magnetic Resonance Microscopy (MRM), showing both qualitative and quantitative agreement. In addition to this, the width of the BM, which is the distance between the primary and secondary osseous spiral laminae, is calculated for the two animals and compared with previous data from the MRM method. For the gerbil cochlea, which does not have much cartilage in the osseous spiral lamina, the μCT-based BM width measurements show good agreement with previous data. The chinchilla BM, which contains more cartilage in the osseous spiral lamina than the gerbil, shows a large difference in the BM widths between the μCT and MRM methods. The SV area, ST area, and BM width measurements from this study can be used in building an anatomically based mathematical cochlear model.

The secondary spiral lamina and its relevance in cochlear implant surgery.

PubMed

Agrawal, Sumit; Schart-Morén, Nadine; Liu, Wei; Ladak, Hanif M; Rask-Andersen, Helge; Li, Hao

2018-03-01

We used synchrotron radiation phase contrast imaging (SR-PCI) to study the 3D microanatomy of the basilar membrane (BM) and its attachment to the spiral ligament (SL) (with a conceivable secondary spiral lamina [SSL] or secondary spiral plate) at the round window membrane (RWM) in the human cochlea. The conception of this complex anatomy may be essential for accomplishing structural preservation at cochlear implant surgery. Sixteen freshly fixed human temporal bones were used to reproduce the BM, SL, primary and secondary osseous spiral laminae (OSL), and RWM using volume-rendering software. Confocal microscopy immunohistochemistry (IHC) was performed to analyze the molecular constituents. SR-PCI reproduced the soft tissues including the RWM, Reissner's membrane (RM), and the BM attachment to the lateral wall (LW) in three dimensions. A variable SR-PCI contrast enhancement was recognized in the caudal part of the SL facing the scala tympani (ST). It seemed to represent a SSL allied to the basilar crest (BC). The SSL extended along the postero-superior margin of the round window (RW) and immunohistochemically expressed type II collagen. Unlike in several mammalian species, the human SSL is restricted to the most basal portion of the cochlea around the RW. It anchors the BM and may influence its hydro-mechanical properties. It could also help to shield the BM from the RW. The microanatomy should be considered at cochlear implant surgery.

Response to a pure tone in a nonlinear mechanical-electrical-acoustical model of the cochlea.

PubMed

Meaud, Julien; Grosh, Karl

2012-03-21

In this article, a nonlinear mathematical model is developed based on the physiology of the cochlea of the guinea pig. The three-dimensional intracochlear fluid dynamics are coupled to a micromechanical model of the organ of Corti and to electrical potentials in the cochlear ducts and outer hair cells (OHC). OHC somatic electromotility is modeled by linearized piezoelectric relations whereas the OHC hair-bundle mechanoelectrical transduction current is modeled as a nonlinear function of the hair-bundle deflection. The steady-state response of the cochlea to a single tone is simulated in the frequency domain using an alternating frequency time scheme. Compressive nonlinearity, harmonic distortion, and DC shift on the basilar membrane (BM), tectorial membrane (TM), and OHC potentials are predicted using a single set of parameters. The predictions of the model are verified by comparing simulations to available in vivo experimental data for basal cochlear mechanics. In particular, the model predicts more amplification on the reticular lamina (RL) side of the cochlear partition than on the BM, which replicates recent measurements. Moreover, small harmonic distortion and DC shifts are predicted on the BM, whereas more significant harmonic distortion and DC shifts are predicted in the RL and TM displacements and in the OHC potentials. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

ATP-gamma-S shifts the operating point of outer hair cell transduction towards scala tympani.

PubMed

Bobbin, Richard P; Salt, Alec N

2005-07-01

ATP receptor agonists and antagonists alter cochlear mechanics as measured by changes in distortion product otoacoustic emissions (DPOAE). Some of the effects on DPOAEs are consistent with the hypothesis that ATP affects mechano-electrical transduction and the operating point of the outer hair cells (OHCs). This hypothesis was tested by monitoring the effect of ATP-gamma-S on the operating point of the OHCs. Guinea pigs anesthetized with urethane and with sectioned middle ear muscles were used. The cochlear microphonic (CM) was recorded differentially (scala vestibuli referenced to scala tympani) across the basal turn before and after perfusion (20 min) of the perilymph compartment with artificial perilymph (AP) and ATP-gamma-S dissolved in AP. The operating point was derived from the cochlear microphonics (CM) recorded in response low frequency (200 Hz) tones at high level (106, 112 and 118 dB SPL). The analysis procedure used a Boltzmann function to simulate the CM waveform and the Boltzmann parameters were adjusted to best-fit the calculated waveform to the CM. Compared to the initial perfusion with AP, ATP-gamma-S (333 microM) enhanced peak clipping of the positive peak of the CM (that occurs during organ of Corti displacements towards scala tympani), which was in keeping with ATP-induced displacement of the transducer towards scala tympani. CM waveform analysis quantified the degree of displacement and showed that the changes were consistent with the stimulus being centered on a different region of the transducer curve. The change of operating point meant that the stimulus was applied to a region of the transducer curve where there was greater saturation of the output on excursions towards scala tympani and less saturation towards scala vestibuli. A significant degree of recovery of the operating point was observed after washing with AP. Dose response curves generated by perfusing ATP-gamma-S (333 microM) in a cumulative manner yielded an EC(50) of 19.8 microM. The ATP antagonist PPADS (0.1 mM) failed to block the effect of ATP-gamma-S on operating point, suggesting the response was due to activation of metabotropic and not ionotropic ATP receptors. Multiple perfusions of AP had no significant effect (118 and 112 dB) or moved the operating point slightly (106 dB) in the direction opposite of ATP-gamma-S. Results are consistent with an ATP-gamma-S induced transducer change comparable to a static movement of the organ of Corti or reticular lamina towards scala tympani.

Cochlear perfusion with a viscous fluid.

PubMed

Wang, Yi; Olson, Elizabeth S

2016-07-01

The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawn from basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner's membrane (RM), while in cochleae perfused with 0.125% and 0.25% HA RM was torn. Thus, the CAP threshold elevation was likely due to the broken RM, likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed, perhaps due to the presence and then clearance of viscous fluid within the cochlea, or to a temporary position shift of the Organ of Corti. After 0.5% HA perfusion, a short latency positive peak (P0) appeared in the CAP waveform. This P0 might be due to a change in the cochlea's traveling-wave pattern, or distortion in the cochlear microphonic. Copyright © 2016 Elsevier B.V. All rights reserved.

Cochlear perfusion with a viscous fluid

PubMed Central

Wang, Yi; Olson, Elizabeth S.

2016-01-01

The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawnfrom basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner’s membrane, while in cochleae perfused with 0.125% and 0.25% HA Reissner’s membrane (RM) was torn. Thus, the CAP threshold elevation was likely due to the broken of RM, which likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed, perhaps due to the presence and then clearance of viscous fluid within the cochlea, or to a temporary position shift of the Organ of Corti. After 0.5% HA perfusion, a short latency positive peak (P0) appeared in the CAP wavefrom. This P0 might be due to a change in the cochlea’s traveling-wave pattern, or distortion in the cochlear microphonic. PMID:27220484

Auditory training improves auditory performance in cochlear implanted children.

PubMed

Roman, Stephane; Rochette, Françoise; Triglia, Jean-Michel; Schön, Daniele; Bigand, Emmanuel

2016-07-01

While the positive benefits of pediatric cochlear implantation on language perception skills are now proven, the heterogeneity of outcomes remains high. The understanding of this heterogeneity and possible strategies to minimize it is of utmost importance. Our scope here is to test the effects of an auditory training strategy, "sound in Hands", using playful tasks grounded on the theoretical and empirical findings of cognitive sciences. Indeed, several basic auditory operations, such as auditory scene analysis (ASA) are not trained in the usual therapeutic interventions in deaf children. However, as they constitute a fundamental basis in auditory cognition, their development should imply general benefit in auditory processing and in turn enhance speech perception. The purpose of the present study was to determine whether cochlear implanted children could improve auditory performances in trained tasks and whether they could develop a transfer of learning to a phonetic discrimination test. Nineteen prelingually unilateral cochlear implanted children without additional handicap (4-10 year-olds) were recruited. The four main auditory cognitive processing (identification, discrimination, ASA and auditory memory) were stimulated and trained in the Experimental Group (EG) using Sound in Hands. The EG followed 20 training weekly sessions of 30 min and the untrained group was the control group (CG). Two measures were taken for both groups: before training (T1) and after training (T2). EG showed a significant improvement in the identification, discrimination and auditory memory tasks. The improvement in the ASA task did not reach significance. CG did not show any significant improvement in any of the tasks assessed. Most importantly, improvement was visible in the phonetic discrimination test for EG only. Moreover, younger children benefited more from the auditory training program to develop their phonetic abilities compared to older children, supporting the idea that rehabilitative care is most efficient when it takes place early on during childhood. These results are important to pinpoint the auditory deficits in CI children, to gather a better understanding of the links between basic auditory skills and speech perception which will in turn allow more efficient rehabilitative programs. Copyright © 2016 Elsevier B.V. All rights reserved.

[Personalized molecular medicine: new paradigms in the treatment of cochlear implant and cancer patients].

PubMed

Zenner, H P; Pfister, M; Friese, N; Zrenner, E; Röcken, M

2014-07-01

To evaluate present options for the indication of cochlear implants (CI) and new forms of treatment for head and neck cancer, melanomas and basal cell carcinomas, with emphasis on future perspectives. A literature search was performed in the PubMed database. Search parameters were "personalized medicine", "individualized medicine" and "molecular medicine". Personalized medicine based on molecular-genetic evaluation of functional proteins such as otoferlin, connexin 26 and KCNQ4 or the Usher gene is becoming increasingly important for the indication of CI in the context of infant deafness. Determination of HER2/EGFR mutations in the epithelial growth factor receptor (EGFR) gene may be an important prognostic parameter for therapeutic decisions in head and neck cancer patients. In basal cell carcinoma therapy, mutations in the Hedgehog (PCTH1) and Smoothened (SMO) pathways strongly influence the indication of therapeutic Hedgehog inhibition, e.g. using small molecules. Analyses of c-Kit receptor, BRAF-600E and NRAS mutations are required for specific molecular therapy of metastasizing melanomas. The significant advances in the field of specific molecular therapy are best illustrated by the availability of the first gene therapeutic procedures for treatment of RPE65-induced infantile retinal degradation. The aim of personalized molecular medicine is to identify patients who will respond particularly positively or negatively (e.g. in terms of adverse side effects) to a therapy using the methods of molecular medicine. This should allow a specific therapy to be successfully applied or preclude its indication in order to avoid serious adverse side effects. This approach serves to stratify patients for adequate treatment.

Intracochlear electrical stimulation suppresses apoptotic signaling in rat spiral ganglion neurons after deafening in vivo.

PubMed

Kopelovich, Jonathan C; Cagaanan, Alain P; Miller, Charles A; Abbas, Paul J; Green, Steven H

2013-11-01

To establish the intracellular consequences of electrical stimulation to spiral ganglion neurons after deafferentation. Here we use a rat model to determine the effect of both low and high pulse rate acute electrical stimulation on activation of the proapoptotic transcription factor Jun in deafferented spiral ganglion neurons in vivo. Experimental animal study. Hearing research laboratories of the University of Iowa Departments of Biology and Otolaryngology. A single electrode was implanted through the round window of kanamycin-deafened rats at either postnatal day 32 (P32, n = 24) or P60 (n = 22) for 4 hours of stimulation (monopolar, biphasic pulses, amplitude twice electrically evoked auditory brainstem response [eABR] threshold) at either 100 or 5000 Hz. Jun phosphorylation was assayed by immunofluorescence to quantitatively assess the effect of electrical stimulation on proapoptotic signaling. Jun phosphorylation was reliably suppressed by 100 Hz stimuli in deafened cochleae of P32 but not P60 rats. This effect was not significant in the basal cochlear turns. Stimulation frequency may be consequential: 100 Hz was significantly more effective than was 5 kHz stimulation in suppressing phospho-Jun. Suppression of Jun phosphorylation occurs in deafferented spiral ganglion neurons after only 4 hours of electrical stimulation. This finding is consistent with the hypothesis that electrical stimulation can decrease spiral ganglion neuron death after deafferentation.

Prediction of the characteristics of two types of pressure waves in the cochlea: Theoretical considerations

NASA Astrophysics Data System (ADS)

Andoh, Masayoshi; Wada, Hiroshi

2004-07-01

The aim of this study was to predict the characteristics of two types of cochlear pressure waves, so-called fast and slow waves. A two-dimensional finite-element model of the organ of Corti (OC), including fluid-structure interaction with the surrounding lymph fluid, was constructed. The geometry of the OC at the basal turn was determined from morphological measurements of others in the gerbil hemicochlea. As far as mechanical properties of the materials within the OC are concerned, previously determined mechanical properties of portions within the OC were adopted, and unknown mechanical features were determined from the published measurements of static stiffness. Time advance of the fluid-structure scheme was achieved by a staggered approach. Using the model, the magnitude and phase of the fast and slow waves were predicted so as to fit the numerically obtained pressure distribution in the scala tympani with what is known about intracochlear pressure measurement. When the predicted pressure waves were applied to the model, the numerical result of the velocity of the basilar membrane showed good agreement with the experimentally obtained velocity of the basilar membrane documented by others. Thus, the predicted pressure waves appeared to be reliable. Moreover, it was found that the fluid-structure interaction considerably influences the dynamic behavior of the OC at frequencies near the characteristic frequency.

Cochlear excitation by the near-field component during stimulation through the partially occluded round window

NASA Astrophysics Data System (ADS)

Weddell, Thomas D.; Yarin, Yury M.; Drexl, Markus; Russell, Ian J.; Elliott, Stephen J.; Lukashkin, Andrei N.

2015-12-01

The round window membrane (RW) provides pressure relief when the cochlea is excited by sound. While normal function of the RW is important for effective stimulation of the cochlea through the conventional oval window route, the cochlea can be stimulated successfully in non-conventional ways (e.g. through bone conduction, through the RW, and through perforations in the cochlea's apical turn). We report measurements of cochlear function from guinea pigs when the cochlea was stimulated at acoustic frequencies by movements of a miniature magnet which partially occluded the RW. Neural response latencies to acoustic and RW stimulation were similar and taken to indicate that both means of stimulation resulted in the generation of conventional travelling waves along the cochlear partition. It was concluded that the relatively high impedance of the ossicles, as seen from the cochlea, enabled the region of the RW not occluded by the magnet, to act as a pressure shunt during RW stimulation. We propose that travelling waves, similar to those due to acoustic far-field pressure changes, are driven by a jet-like, near-field component of a complex fluid-pressure field, which is generated by the magnetically vibrated RW.

Basilar membrane vibration after targeted removal of the third row of OHCs and Deiters cells

NASA Astrophysics Data System (ADS)

Xia, Anping; Udagawa, Tomokatsu; Raphael, Patrick D.; Cheng, Alan G.; Steele, Charles R.; Applegate, Brian E.; Oghalai, John S.

2018-05-01

The mammalian cochlea has three rows of outer hair cells (OHCs) that amplify the basilar membrane (BM) traveling wave with high gain and exquisite sharpness. However, it is unclear why three rows of OHCs are needed to achieve this. We used a novel transgenic mouse with the diphtheria toxin receptor in Lgr5-positive cells (Lgr5DTR-EGFP/+ mouse) that allowed us to ablate the third row of OHCs and Deiters cells (D) in adulthood via DT injection, after normal cochlear function had developed. We then used volumetric optical coherence tomography (VOCTV) to investigate the impacts of this manipulation of cochlear amplification in the apical turn. As expected, Lgr5DTR-EGFP/+ control mice had sharply-tuned vibratory responses. However, Lgr5DTR-EGFP/+ mice had broad tuning with a 20 dB increase in vibratory thresholds. The Q10dB was ˜1 in Lgr5DTR-EGFP/+ mice, whereas it was ˜3 in control mice. The characteristic frequency was lower in Lgr5DTR-EGFP/+ mice compared to controls (7.5 vs. 9.0 kHz). The gain of cochlear amplification was substantially lower in Lgr5DTR-EGFP/+ mice compared to controls (22 vs. 50). In the post-mortem period, the vibratory responses in Lgr5DTR-EGFP/+ mice were identical to controls. Together, these results demonstrate the substantial importance of the third row of OHCs and Deiters cells to normal cochlear amplification.

Radiologic and functional evaluation of electrode dislocation from the scala tympani to the scala vestibuli in patients with cochlear implants.

PubMed

Fischer, N; Pinggera, L; Weichbold, V; Dejaco, D; Schmutzhard, J; Widmann, G

2015-02-01

Localization of the electrode after cochlear implantation seems to have an impact on auditory outcome, and conebeam CT has emerged as a reliable method for visualizing the electrode array position within the cochlea. The aim of this retrospective study was to evaluate the frequency and clinical impact of scalar dislocation of various electrodes and surgical approaches and to evaluate its influence on auditory outcome. This retrospective single-center study analyzed a consecutive series of 63 cochlear implantations with various straight electrodes. The placement of the electrode array was evaluated by using multiplanar reconstructed conebeam CT images. For the auditory outcome, we compared the aided hearing thresholds and the charge units of maximum comfortable loudness level at weeks 6, 12, and 24 after implantation. In 7.9% of the cases, the electrode array showed scalar dislocation. In all cases, the electrode array penetrated the basal membrane within 45° of the electrode insertion. All 3 cases of cochleostomy were dislocated in the first 45° segment. No hearing differences were noted, but the charge units of maximum comfortable loudness level seemed to increase with time in patients with dislocations. The intracochlear dislocation rate of various straight electrodes detected by conebeam CT images is relatively low. Scalar dislocation may not negatively influence the hearing threshold but may require an increase of the necessary stimulus charge and should be reported by the radiologist. © 2015 by American Journal of Neuroradiology.

Electric-acoustic pitch comparisons in single-sided-deaf cochlear implant users: frequency-place functions and rate pitch.

PubMed

Schatzer, Reinhold; Vermeire, Katrien; Visser, Daniel; Krenmayr, Andreas; Kals, Mathias; Voormolen, Maurits; Van de Heyning, Paul; Zierhofer, Clemens

2014-03-01

Eight cochlear implant users with near-normal hearing in their non-implanted ear compared pitch percepts for pulsatile electric and acoustic pure-tone stimuli presented to the two ears. Six subjects were implanted with a 31-mm MED-EL FLEX(SOFT) electrode, and two with a 24-mm medium (M) electrode, with insertion angles of the most apical contacts ranging from 565° to 758°. In the first experiment, frequency-place functions were derived from pure-tone matches to 1500-pps unmodulated pulse trains presented to individual electrodes and compared to Greenwood's frequency position map along the organ of Corti. While the overall median downward shift of the obtained frequency-place functions (-0.16 octaves re. Greenwood) and the mean shifts in the basal (<240°; -0.33 octaves) and middle (-0.35 octaves) regions were statistically significant, the shift in the apical region (>480°; 0.26 octaves) was not. Standard deviations of frequency-place functions were approximately half an octave at electrode insertion angles below 480°, increasing to an octave at higher angular locations while individual functions were gradually leveling off. In a second experiment, subjects matched the rates of unmodulated pulse trains presented to individual electrodes in the apical half of the array to low-frequency pure tones between 100 Hz and 450 Hz. The aim was to investigate the influence of electrode place on the salience of temporal pitch cues, for coding strategies that present temporal fine structure information via rate modulations on select apical channels. Most subjects achieved reliable matches to tone frequencies from 100 Hz to 300 Hz only on electrodes at angular insertion depths beyond 360°, while rate-matches to 450-Hz tones were primarily achieved on electrodes at shallower insertion angles. Only for electrodes in the second turn the average slopes of rate-pitch functions did not differ significantly from the pure-tone references, suggesting their use for the encoding of within-channel fine frequency information via rate modulations in temporal fine structure stimulation strategies. Copyright © 2013 Elsevier B.V. All rights reserved.

Large endolymphatic potentials from low-frequency and infrasonic tones in the guinea pig.

PubMed

Salt, Alec N; Lichtenhan, Jeffery T; Gill, Ruth M; Hartsock, Jared J

2013-03-01

Responses of the ear to low-frequency and infrasonic sounds have not been extensively studied. Understanding how the ear responds to low frequencies is increasingly important as environmental infrasounds are becoming more pervasive from sources such as wind turbines. This study shows endolymphatic potentials in the third cochlear turn from acoustic infrasound (5 Hz) are larger than from tones in the audible range (e.g., 50 and 500 Hz), in some cases with peak-to-peak amplitude greater than 20 mV. These large potentials were suppressed by higher-frequency tones and were rapidly abolished by perilymphatic injection of KCl at the cochlear apex, demonstrating their third-turn origins. Endolymphatic iso-potentials from 5 to 500 Hz were enhanced relative to perilymphatic potentials as frequency was lowered. Probe and infrasonic bias tones were used to study the origin of the enhanced potentials. Potentials were best explained as a saturating response summed with a sinusoidal voltage (Vo), that was phase delayed by an average of 60° relative to the biasing effects of the infrasound. Vo is thought to arise indirectly from hair cell activity, such as from strial potential changes caused by sustained current changes through the hair cells in each half cycle of the infrasound.

High frequency bone conduction auditory evoked potentials in the guinea pig: Assessing cochlear injury after ossicular chain manipulation.

PubMed

Bergin, M J; Bird, P A; Vlajkovic, S M; Thorne, P R

2015-12-01

Permanent high frequency (>4 kHz) sensorineural hearing loss following middle ear surgery occurs in up to 25% of patients. The aetiology of this loss is poorly understood and may involve transmission of supra-physiological forces down the ossicular chain to the cochlea. Investigating the mechanisms of this injury using animal models is challenging, as evaluating cochlear function with evoked potentials is confounded when ossicular manipulation disrupts the normal air conduction (AC) pathway. Bone conduction (BC) using clinical bone vibrators in small animals is limited by poor transducer output at high frequencies sensitive to trauma. The objectives of the present study were firstly to evaluate a novel high frequency bone conduction transducer with evoked auditory potentials in a guinea pig model, and secondly to use this model to investigate the impact of middle ear surgical manipulation on cochlear function. We modified a magnetostrictive device as a high frequency BC transducer and evaluated its performance by comparison with a calibrated AC transducer at frequencies up to 32 kHz using the auditory brainstem response (ABR), compound action potential (CAP) and summating potential (SP). To mimic a middle ear traumatising stimulus, a rotating bur was brought in to contact with the incudomalleal complex and the effect on evoked cochlear potentials was observed. BC-evoked potentials followed the same input-output function pattern as AC potentials for all ABR frequencies. Deterioration in CAP and SP thresholds was observed after ossicular manipulation. It is possible to use high frequency BC to evoke responses from the injury sensitive basal region of the cochlea and so not rely on AC with the potential confounder of conductive hearing loss. Ongoing research explores how these findings evolve over time, and ways in which injury may be reduced and the cochlea protected during middle ear surgery. Copyright © 2015 Elsevier B.V. All rights reserved.

A cool approach to reducing electrode-induced trauma: Localized therapeutic hypothermia conserves residual hearing in cochlear implantation.

PubMed

Tamames, Ilmar; King, Curtis; Bas, Esperanza; Dietrich, W Dalton; Telischi, Fred; Rajguru, Suhrud M

2016-09-01

The trauma caused during cochlear implant insertion can lead to cell death and a loss of residual hair cells in the cochlea. Various therapeutic approaches have been studied to prevent cochlear implant-induced residual hearing loss with limited success. In the present study, we show the efficacy of mild to moderate therapeutic hypothermia of 4 to 6 °C applied to the cochlea in reducing residual hearing loss associated with the electrode insertion trauma. Rats were randomly distributed in three groups: control contralateral cochleae, normothermic implanted cochleae and hypothermic implanted cochleae. Localized hypothermia was delivered to the middle turn of the cochlea for 20 min before and after implantation using a custom-designed probe perfused with cooled fluorocarbon. Auditory brainstem responses (ABRs) were recorded to assess the hearing function prior to and post-cochlear implantation at various time points up to 30 days. At the conclusion of the trials, inner ears were harvested for histology and cell count. The approach was extended to cadaver temporal bones to study the potential surgical approach and efficacy of our device. In this case, the hypothermia probe was placed next to the round window niche via the facial recess or a myringotomy. A significant loss of residual hearing was observed in the normothermic implant group. Comparatively, the residual hearing in the cochleae receiving therapeutic hypothermia was significantly conserved. Histology confirmed a significant loss of outer hair cells in normothermic cochleae receiving the surgical trauma when compared to the hypothermia treated group. In human temporal bones, a controlled and effective cooling of the cochlea was achieved using our approach. Collectively, these results suggest that therapeutic hypothermia during cochlear implantation may reduce traumatic effects of electrode insertion and improve conservation of residual hearing. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Perceptual consequences of normal and abnormal peripheral compression: Potential links between psychoacoustics and speech perception

NASA Astrophysics Data System (ADS)

Oxenham, Andrew J.; Rosengard, Peninah S.; Braida, Louis D.

2004-05-01

Cochlear damage can lead to a reduction in the overall amount of peripheral auditory compression, presumably due to outer hair cell (OHC) loss or dysfunction. The perceptual consequences of functional OHC loss include loudness recruitment and reduced dynamic range, poorer frequency selectivity, and poorer effective temporal resolution. These in turn may lead to a reduced ability to make use of spectral and temporal fluctuations in background noise when listening to a target sound, such as speech. We tested the effect of OHC function on speech reception in hearing-impaired listeners by comparing psychoacoustic measures of cochlear compression and sentence recognition in a variety of noise backgrounds. In line with earlier studies, we found weak (nonsignificant) correlations between the psychoacoustic tasks and speech reception thresholds in quiet or in steady-state noise. However, when spectral and temporal fluctuations were introduced in the masker, speech reception improved to an extent that was well predicted by the psychoacoustic measures. Thus, our initial results suggest a strong relationship between measures of cochlear compression and the ability of listeners to take advantage of spectral and temporal masker fluctuations in recognizing speech. [Work supported by NIH Grants Nos. R01DC03909, T32DC00038, and R01DC00117.

Noise alters guinea pig's blood-labyrinth barrier ultrastructure and permeability along with a decrease of cochlear Claudin-5 and Occludin.

PubMed

Wu, Yong-Xiang; Zhu, Guo-Xia; Liu, Xin-Qin; Sun, Fei; Zhou, Ke; Wang, Shuang; Wang, Chun-Mei; Jia, Jin-Wen; Song, Jian-Tao; Lu, Lian-Jun

2014-12-24

Noise exposure (NE) is a severe modern health hazard that induces hearing impairment. However, the noise-induced ultrastructural changes of blood-labyrinth barrier (BLB) and the potential involvements of tight junction proteins (TJP) remain inconclusive. We investigated the effects of NE on not only the ultrastructure of cochlea and permeability of BLB but also the expression of TJP within the guinea pig cochlea. Male albino guinea pigs were exposed to white noise for 4 h or 2 consecutive days (115 dB sound pressure level, 6 hours per day) and the hearing impairments and light microscopic change of BLB were evaluated with auditory brainstem responses (ABR) and the cochlear sensory epithelia surface preparation, respectively. The cochlear ultrastructure and BLB permeability after NE 2d were revealed with transmission electron microscope (TEM) and lanthanum nitrate-tracing techniques, respectively. The potential alterations of TJPs Claudin-5 and Occludin were quantified with immunohistochemistry and western blot. NE induced significant hearing impairment and NE 2d contributed to significant outer hair cell (OHC) loss that is most severe in the first row of outer hair cells. Furthermore, the loosen TJ and an obvious leakage of lanthanum nitrate particles beneath the basal lamina were revealed with TEM. Moreover, a dose-dependent decrease of Claudin-5 and Occludin was observed in the cochlea after NE. All these findings suggest that both decrease of Claudin-5 and Occludin and increased BLB permeability are involved in the pathologic process of noise-induced hearing impairment; however, the causal relationship and underlying mechanisms should be further investigated.

Does cochlear implantation and electrical stimulation affect residual hair cells and spiral ganglion neurons?

PubMed Central

Coco, Anne; Epp, Stephanie B.; Fallon, James B.; Xu, Jin; Millard, Rodney E.; Shepherd, Robert K.

2007-01-01

Increasing numbers of cochlear implant subjects have some level of residual hearing at the time of implantation. The present study examined whether (i) hair cells that have survived one pathological insult (aminoglycoside deafening), can survive and function following long-term cochlear implantation and electrical stimulation (ES); and (ii) chronic ES in these cochleae results in greater trophic support of spiral ganglion neurons (SGNs) compared with cochleae devoid of hair cells. Eight cats, with either partial (n=4) or severe (n=4) sensorineural hearing loss, were bilaterally implanted with scala tympani electrode arrays 2 months after deafening, and received unilateral ES using charge balanced biphasic current pulses for periods of up to 235 days. Frequency-specific compound action potentials and click-evoked auditory brainstem responses (ABRs) were recorded periodically to monitor the residual acoustic hearing. Electrically-evoked ABRs (EABRs) were recorded to confirm the stimulus levels were 3-6 dB above the EABR threshold. On completion of the ES program the cochleae were examined histologically. Partially deafened animals showed no significant increase in acoustic thresholds over the implantation period. Moreover, chronic ES of an electrode array located in the base of the cochlea did not adversely affect hair cells in the middle or apical turns. There was evidence of a small but statistically significant rescue of SGNs in the middle and apical turns of stimulated cochleae in animals with partial hearing. Chronic ES did not, however, prevent a reduction in SGN density for the severely deaf cohort, although SGNs adjacent to the stimulating electrodes did exhibit a significant increase in soma area (p<0.01). In sum, chronic ES in partial hearing animals does not adversely affect functioning residual hair cells apical to the electrode array. Moreover, while there is an increase in the soma area of SGNs close to the stimulating electrodes in severely deaf cochleae, this trophic effect does not result in increased SGN survival. PMID:17258411

Spatial channel interactions in cochlear implants

NASA Astrophysics Data System (ADS)

Tang, Qing; Benítez, Raul; Zeng, Fan-Gang

2011-08-01

The modern multi-channel cochlear implant is widely considered to be the most successful neural prosthesis owing to its ability to restore partial hearing to post-lingually deafened adults and to allow essentially normal language development in pre-lingually deafened children. However, the implant performance varies greatly in individuals and is still limited in background noise, tonal language understanding, and music perception. One main cause for the individual variability and the limited performance in cochlear implants is spatial channel interaction from the stimulating electrodes to the auditory nerve and brain. Here we systematically examined spatial channel interactions at the physical, physiological, and perceptual levels in the same five modern cochlear implant subjects. The physical interaction was examined using an electric field imaging technique, which measured the voltage distribution as a function of the electrode position in the cochlea in response to the stimulation of a single electrode. The physiological interaction was examined by recording electrically evoked compound action potentials as a function of the electrode position in response to the stimulation of the same single electrode position. The perceptual interactions were characterized by changes in detection threshold as well as loudness summation in response to in-phase or out-of-phase dual-electrode stimulation. To minimize potentially confounding effects of temporal factors on spatial channel interactions, stimulus rates were limited to 100 Hz or less in all measurements. Several quantitative channel interaction indexes were developed to define and compare the width, slope and symmetry of the spatial excitation patterns derived from these physical, physiological and perceptual measures. The electric field imaging data revealed a broad but uniformly asymmetrical intracochlear electric field pattern, with the apical side producing a wider half-width and shallower slope than the basal side. In contrast, the evoked compound action potential and perceptual channel interaction data showed much greater individual variability. It is likely that actual reduction in neural and higher level interactions, instead of simple sharpening of the electric current field, would be the key to predicting and hopefully improving the variable cochlear implant performance. The present results are obtained with auditory prostheses but can be applied to other neural prostheses, in which independent spatial channels, rather than a high stimulation rate, are critical to their performance.

Scala tympani cochleostomy II: topography and histology.

PubMed

Adunka, Oliver F; Radeloff, Andreas; Gstoettner, Wolfgang K; Pillsbury, Harold C; Buchman, Craig A

2007-12-01

To assess intracochlear trauma using two different round window-related cochleostomy techniques in human temporal bones. Twenty-eight human temporal bones were included in this study. In 21 specimens, cochleostomies were initiated inferior to the round window (RW) annulus. In seven bones, cochleostomies were drilled anterior-inferior to the RW annulus. Limited cochlear implant electrode insertions were performed in 19 bones. In each specimen, promontory anatomy and cochleostomy drilling were photographically documented. Basal cochlear damage was assessed histologically and electrode insertion properties were documented in implanted bones. All implanted specimens showed clear scala tympani electrode placements regardless of cochleostomy technique. All 21 inferior cochleostomies were atraumatic. Anterior-inferior cochleostomies resulted in various degrees of intracochlear trauma in all seven bones. For atraumatic opening of the scala tympani using a cochleostomy approach, initiation of drilling should proceed from inferior to the round window annulus, with gradual progression toward the undersurface of the lumen. While cochleostomies initiated anterior-inferior to the round window annulus resulted in scala tympani opening, many of these bones displayed varying degrees of intracochlear trauma that may result in hearing loss. When intracochlear drilling is avoided, the anterior bony margin of the cochleostomy remains a significant intracochlear impediment to in-line electrode insertion.

Migration of cochlear lateral wall cells.

PubMed

Dunaway, George; Mhaskar, Yashanad; Armour, Gary; Whitworth, Craig; Rybak, Leonard

2003-03-01

The role of apoptosis and proliferation in maintenance of cochlear lateral wall cells was examined. The methods employed for detection of apoptosis were the Hoechst fluorescence stain and TUNEL (TdT-mediated dUTP-biotin nick-end-labeling) assay, and proliferations were 5-bromo-2'-deoxyuridine (BrdU) incorporation and presence of the proliferating cell nuclear antigen. The incidence of apoptosis in the strial marginal cell was 50% greater (32.9+/-3.7%) than strial intermediate and basal cells but similar to spiral ligament cells. Although division of marginal strial cells was rarely detected, a significant number of proliferating cells in the remaining stria vascularis and spiral ligament were observed. These data implied that replacement of marginal cells arose elsewhere and could be followed by a BrdU-deoxythymidine pulse-chase study. At 2 h post injection, nuclear BrdU in marginal cells was not detected; however, by 24 h post injection, 20-25% of marginal cell nuclei were BrdU-positive. These observations are consistent with the hypothesis that marginal cells were replaced by underlying cells. Cell migration appears to be an important mechanism for preserving the function and structure of the stria vascularis.

Intensity coding in electric hearing: effects of electrode configurations and stimulation waveforms.

PubMed

Chua, Tiffany Elise H; Bachman, Mark; Zeng, Fan-Gang

2011-01-01

Current cochlear implants typically stimulate the auditory nerve with biphasic pulses and monopolar electrode configurations. Tripolar stimulation can increase spatial selectivity and potentially improve place pitch related perception but requires higher current levels to elicit the same loudness as monopolar stimulation. The present study combined delayed pseudomonophonasic pulses, which produce lower thresholds, with tripolar stimulation in an attempt to solve the power-performance tradeoff problem. The present study systematically measured thresholds, dynamic range, loudness growth, and intensity discrimination using either biphasic or delayed pseudomonophonasic pulses under both monopolar and tripolar stimulation. Participants were five Clarion cochlear implant users. For each subject, data from apical, middle, and basal electrode positions were collected when possible. Compared with biphasic pulses, delayed pseudomonophonasic pulses increased the dynamic range by lowering thresholds while maintaining comparable maximum allowable levels under both electrode configurations. However, delayed pseudomonophonasic pulses did not change the shape of loudness growth function and actually increased intensity discrimination limens, especially at lower current levels. The present results indicate that delayed pseudomonophonasic pulses coupled with tripolar stimulation cannot provide significant power savings nor can it increase the functional dynamic range. Whether this combined stimulation could improve functional spectral resolution remains to be seen.

Pitch ranking, electrode discrimination, and physiological spread of excitation using current steering in cochlear implants

PubMed Central

Goehring, Jenny L.; Neff, Donna L.; Baudhuin, Jacquelyn L.; Hughes, Michelle L.

2014-01-01

The first objective of this study was to determine whether adaptive pitch-ranking and electrode-discrimination tasks with cochlear-implant (CI) recipients produce similar results for perceiving intermediate “virtual-channel” pitch percepts using current steering. Previous studies have not examined both behavioral tasks in the same subjects with current steering. A second objective was to determine whether a physiological metric of spatial separation using the electrically evoked compound action potential spread-of-excitation (ECAP SOE) function could predict performance in the behavioral tasks. The metric was the separation index (Σ), defined as the difference in normalized amplitudes between two adjacent ECAP SOE functions, summed across all masker electrodes. Eleven CII or 90 K Advanced Bionics (Valencia, CA) recipients were tested using pairs of electrodes from the basal, middle, and apical portions of the electrode array. The behavioral results, expressed as d′, showed no significant differences across tasks. There was also no significant effect of electrode region for either task. ECAP Σ was not significantly correlated with pitch ranking or electrode discrimination for any of the electrode regions. Therefore, the ECAP separation index is not sensitive enough to predict perceptual resolution of virtual channels. PMID:25480063

The BEACH protein LRBA is required for hair bundle maintenance in cochlear hair cells and for hearing.

PubMed

Vogl, Christian; Butola, Tanvi; Haag, Natja; Hausrat, Torben J; Leitner, Michael G; Moutschen, Michel; Lefèbvre, Philippe P; Speckmann, Carsten; Garrett, Lillian; Becker, Lore; Fuchs, Helmut; Hrabe de Angelis, Martin; Nietzsche, Sandor; Kessels, Michael M; Oliver, Dominik; Kneussel, Matthias; Kilimann, Manfred W; Strenzke, Nicola

2017-11-01

Lipopolysaccharide-responsive beige-like anchor protein (LRBA) belongs to the enigmatic class of BEACH domain-containing proteins, which have been attributed various cellular functions, typically involving intracellular protein and membrane transport processes. Here, we show that LRBA deficiency in mice leads to progressive sensorineural hearing loss. In LRBA knockout mice, inner and outer hair cell stereociliary bundles initially develop normally, but then partially degenerate during the second postnatal week. LRBA deficiency is associated with a reduced abundance of radixin and Nherf2, two adaptor proteins, which are important for the mechanical stability of the basal taper region of stereocilia. Our data suggest that due to the loss of structural integrity of the central parts of the hair bundle, the hair cell receptor potential is reduced, resulting in a loss of cochlear sensitivity and functional loss of the fraction of spiral ganglion neurons with low spontaneous firing rates. Clinical data obtained from two human patients with protein-truncating nonsense or frameshift mutations suggest that LRBA deficiency may likewise cause syndromic sensorineural hearing impairment in humans, albeit less severe than in our mouse model. © 2017 The Authors.

A Stem Cell-Seeded Nanofibrous Scaffold for Auditory Nerve Replacement

DTIC Science & Technology

2013-10-01

the brightest GFP+ cells by flow cytometry and compared these with GFP- cells (Figure 1A-C). The transfected cells showed robust GFP expression even...al., 2011), but no normative data were provided on SGN loss by cochlear turn and, in contrast to our results, those authors reported no impact on...A) Flow cytometry analysis to identify GFP+ and GFP- cells. The large cluster of cells on the left represent the GFP- cells and exhibited similar

Cell polarity proteins and spermatogenesis.

PubMed

Gao, Ying; Xiao, Xiang; Lui, Wing-Yee; Lee, Will M; Mruk, Dolores; Cheng, C Yan

2016-11-01

When the cross-section of a seminiferous tubule from an adult rat testes is examined microscopically, Sertoli cells and germ cells in the seminiferous epithelium are notably polarized cells. For instance, Sertoli cell nuclei are found near the basement membrane. On the other hand, tight junction (TJ), basal ectoplasmic specialization (basal ES, a testis-specific actin-rich anchoring junction), gap junction (GJ) and desmosome that constitute the blood-testis barrier (BTB) are also located near the basement membrane. The BTB, in turn, divides the epithelium into the basal and the adluminal (apical) compartments. Within the epithelium, undifferentiated spermatogonia and preleptotene spermatocytes restrictively reside in the basal compartment whereas spermatocytes and post-meiotic spermatids reside in the adluminal compartment. Furthermore, the heads of elongating/elongated spermatids point toward the basement membrane with their elongating tails toward the tubule lumen. However, the involvement of polarity proteins in this unique cellular organization, in particular the underlying molecular mechanism(s) by which polarity proteins confer cellular polarity in the seminiferous epithelium is virtually unknown until recent years. Herein, we discuss latest findings regarding the role of different polarity protein complexes or modules and how these protein complexes are working in concert to modulate Sertoli cell and spermatid polarity. These findings also illustrate polarity proteins exert their effects through the actin-based cytoskeleton mediated by actin binding and regulatory proteins, which in turn modulate adhesion protein complexes at the cell-cell interface since TJ, basal ES and GJ utilize F-actin for attachment. We also propose a hypothetical model which illustrates the antagonistic effects of these polarity proteins. This in turn provides a unique mechanism to modulate junction remodeling in the testis to support germ cell transport across the epithelium in particular the BTB during the epithelial cycle of spermatogenesis. Copyright © 2016 Elsevier Ltd. All rights reserved.

[The Heidelberg CI database module : Quality control in hearing restoration with cochlear implants].

PubMed

Herisanu, I T; Hoth, S; Praetorius, M

2016-12-01

Cochlear implants (CI) have been established as the therapy of choice for functional deafness. The number of CI-rehabilitated patients is continuously growing. The resulting data can provide important information for physicians, health insurance companies, and scientists. Assessment and structuring of data becomes more feasible with the application of modern database systems. In collaboration with Innoforce Est., Liechtenstein, the authors developed a database module for the specific needs of CI patients. Data of 100 patients were included and evaluated. The main features of the module and an example data analysis are presented. Analysis of data from these 100 patients reveals 50 men and 50 women aged between 1 and 87 years, with a maximum value in the 51-60-years age group. More than 50% of the patients were also severely hearing impaired in the contralateral ear and fitted the CI indication criteria. Functional deafness in the ear subsequently fitted with CI in most of the patients had arisen more than 20 years previously. Preoperative diagnostic electrical stimulation of the cochlear nerve was positive in 67 patients. All 100 patients perceived auditory sensations with the CI. The presented patient cohort is representative of patients at the Department of Otorhinolaryngology, University of Heidelberg Medical Center, Germany, and the demographic distribution is in accordance with the literature. The state of the contralateral ear, often also fitting the CI indication, is not surprising, as cochlear implantation is a comparatively new procedure. Preoperative electrical stimulation turned out not to be significant by itself. The hearing results and overview of complications were easy to calculate in comparison to a pure data storage system such as i.s.h.med.

Cortical activation patterns correlate with speech understanding after cochlear implantation

PubMed Central

Olds, Cristen; Pollonini, Luca; Abaya, Homer; Larky, Jannine; Loy, Megan; Bortfeld, Heather; Beauchamp, Michael S.; Oghalai, John S.

2015-01-01

Objectives Cochlear implants are a standard therapy for deafness, yet the ability of implanted patients to understand speech varies widely. To better understand this variability in outcomes, we used functional near-infrared spectroscopy (fNIRS) to image activity within regions of the auditory cortex and compare the results to behavioral measures of speech perception. Design We studied 32 deaf adults hearing through cochlear implants and 35 normal-hearing controls. We used fNIRS to measure responses within the lateral temporal lobe and the superior temporal gyrus to speech stimuli of varying intelligibility. The speech stimuli included normal speech, channelized speech (vocoded into 20 frequency bands), and scrambled speech (the 20 frequency bands were shuffled in random order). We also used environmental sounds as a control stimulus. Behavioral measures consisted of the Speech Reception Threshold, CNC words, and AzBio Sentence tests measured in quiet. Results Both control and implanted participants with good speech perception exhibited greater cortical activations to natural speech than to unintelligible speech. In contrast, implanted participants with poor speech perception had large, indistinguishable cortical activations to all stimuli. The ratio of cortical activation to normal speech to that of scrambled speech directly correlated with the CNC Words and AzBio Sentences scores. This pattern of cortical activation was not correlated with auditory threshold, age, side of implantation, or time after implantation. Turning off the implant reduced cortical activations in all implanted participants. Conclusions Together, these data indicate that the responses we measured within the lateral temporal lobe and the superior temporal gyrus correlate with behavioral measures of speech perception, demonstrating a neural basis for the variability in speech understanding outcomes after cochlear implantation. PMID:26709749

Selective damage to cochlear efferents by the choline neurotoxin ethylcholine mustard aziridinium ion (AF64A) in the chinchilla.

PubMed

Smith, D W; Mount, R J; Callahan, J W

1989-10-01

The cholinotoxin ethylcholine mustard aziridinium ion (AF64A) was diluted in artificial perilymph to concentrations ranging from 10-100 microM, injected unilaterally into the bulla of chinchillas, and allowed to passively diffuse across the round window membrane. Following 21-day survival, the animals were sacrificed and ears removed and embedded in epoxy for histological evaluation under both light and transmission electron microscopy. At 10 microM concentration, selective degeneration of efferent fibers was observed in the efferent terminals on outer hair cells (OHC), tunnel radial fibers, tunnel spiral bundle, and the inner spiral bundle. Serial sections of the middle turn of an animal at 10 microM concentrations showed normal efferent terminals on approximately 50% of OHCs. At the higher concentrations non-specific damage was seen in OHCs, afferents, and some supporting cells. These data suggest that low doses AF64A produces selective damage to cochlear efferent terminals and fibers in the chinchilla.

Promoting lexical learning in the speech and language therapy of children with cochlear implants.

PubMed

Ronkainen, Riitta; Laakso, Minna; Lonka, Eila; Tykkyläinen, Tuula

2017-01-01

This study examines lexical intervention sessions in speech and language therapy for children with cochlear implants (CIs). Particular focus is on the therapist's professional practices in doing the therapy. The participants in this study are three congenitally deaf children with CIs together with their speech and language therapist. The video recorded therapy sessions of these children are studied using conversation analysis. The analysis reveals the ways in which the speech and language therapist formulates her speaking turns to support the children's lexical learning in task interaction. The therapist's multimodal practices, for example linguistic and acoustic highlighting, focus both on the lexical meaning and the phonological form of the words. Using these means, the therapist expands the child's lexical networks, specifies and corrects the meaning of the target words, and models the correct phonological form of the words. The findings of this study are useful in providing information for clinicians and speech and language therapy students working with children who have CIs as well as for the children's parents.

Photochemically induced focal cochlear lesions in the guinea pig: II. A transmission electron microscope study.

PubMed

Miyashita, H; Iwasaki, S; Hoshino, T

1998-05-15

Photochemically induced focal lesions in guinea pig cochleas were studied by light microscopy and transmission electron microscopy. The lesions were induced in the second cochlear turns of 35 adult guinea pigs by illumination for 10 minutes with a focused green light immediately after a rose bengal solution was injected into the jugular vein. The cochlear lateral wall and organ of Corti were examined 5, 10, 20, 30, and 90 minutes, 12 and 24 hours, and 3, 7, and 30 days after the procedure. Aggregations of platelets and red blood cells were found in strial capillaries at 5 minutes after illumination. After 30 minutes, marginal cell surfaces protruded into the endolymphatic space; surface membranes were ruptured and the cytoplasm was expelled into the space. In outer hair cells, disruption of the cellular membrane was found near the cuticular plate 12 hours after the procedure. All cellular elements of the lateral wall and organ of Corti were markedly degenerated in the 30-day specimens. Histological changes found in the stria vascularis were consistent with cell damage caused by active oxygen species. It is likely that the stria vascularis is more sensitive to the photochemical reaction than other parts of the cochlea. Cell damage in other parts of the cochlea seemed to have been caused by local microvascular ischemia in addition to the action of active oxygen species induced by the photochemical reaction.

Infection-Mediated Vasoactive Peptides Modulate Cochlear Uptake of Fluorescent Gentamicin

PubMed Central

Koo, Ja-Won; Wang, Qi; Steyger, Peter S.

2011-01-01

Inflammatory mediators released during bacterial infection include vasoactive peptides such as histamine and serotonin, and their serum levels are frequently elevated. These peptides also modulate the vascular permeability of endothelial cells lining the blood-brain and blood-labyrinth barriers (BLB). These peptides may also modulate the permeability of the BLB to ototoxic aminoglycoside antibiotics prescribed to resolve bacterial sepsis. To test this hypothesis, we compared the effect of histamine and serotonin on the cochlear distribution of fluorescently conjugated gentamicin (GTTR) in control animals at 0.5, 1 and 3 h after injection of GTTR. The intensity of GTTR fluorescence was attenuated at 1 h in the histamine group compared to control mice, and more intense 3 h after injection (p < 0.05). In the serotonin group, the intensity of GTTR fluorescence was attenuated at 0.5 and 1 h (p < 0.05) and was increased at 3 h compared to control animals, where GTTR intensities peaked at 1 h and then plateaued or was slightly decreased at 3 h. This biphasic pattern of modulation was statistically significant in the apical turn of the cochlea. No difference in the intensity of GTTR fluorescence was observed in kidney proximal tubules. Systemic increases in serum levels of vasoactive peptides can modulate cochlear uptake of gentamicin, likely via permeability changes in the BLB. Conditions that influence serum levels of vasoactive peptides may potentiate aminoglycoside ototoxicity. PMID:21196726

Masking of sounds by a background noise--cochlear mechanical correlates.

PubMed

Recio-Spinoso, Alberto; Cooper, Nigel P

2013-05-15

In the search for cochlear correlates of auditory masking by noise stimuli, we recorded basilar membrane (BM) vibrations evoked by either tone or click signals in the presence of varying levels of background noise. The BM vibrations were recorded from basal regions in healthy cochleae of anaesthetized chinchilla and gerbil. Non-linear interactions that could underpin various aspects of psychophysical masking data, including both compression and suppression at the BM level, were observed. The suppression effects, whereby the amplitude of the responses to each stimulus component could be reduced, depended on the relative intensities of the noise and the tones or clicks. Only stimulus components whose frequencies fell inside the non-linear region of the recording site, i.e. around its characteristic frequency (CF), were affected by presentation of the 'suppressing' stimulus (which could be either the tone or the noise). Mutual suppression, the simultaneous reduction of the responses to both tones and noise components, was observed under some conditions, but overall reductions of BM vibration were rarely observed. Moderate- to high-intensity tones suppressed BM responses to low-intensity Gaussian stimuli, including both broadband and narrowband noise. Suppression effects were larger for spectral components of the noise response that were closer to the CF. In this regime, the tone and noise stimuli became the suppressor and probe signals, respectively. This study provides the first detailed observations of cochlear mechanical correlates of the masking effects of noise. Mechanical detection thresholds for tone signals, which were arbitrarily defined using three criteria, are shown to increase in almost direct proportion to the noise level for low and moderately high noise levels, in a manner that resembles the findings of numerous psychophysical observations.

Masking of sounds by a background noise – cochlear mechanical correlates

PubMed Central

Recio-Spinoso, Alberto; Cooper, Nigel P

2013-01-01

In the search for cochlear correlates of auditory masking by noise stimuli, we recorded basilar membrane (BM) vibrations evoked by either tone or click signals in the presence of varying levels of background noise. The BM vibrations were recorded from basal regions in healthy cochleae of anaesthetized chinchilla and gerbil. Non-linear interactions that could underpin various aspects of psychophysical masking data, including both compression and suppression at the BM level, were observed. The suppression effects, whereby the amplitude of the responses to each stimulus component could be reduced, depended on the relative intensities of the noise and the tones or clicks. Only stimulus components whose frequencies fell inside the non-linear region of the recording site, i.e. around its characteristic frequency (CF), were affected by presentation of the ‘suppressing’ stimulus (which could be either the tone or the noise). Mutual suppression, the simultaneous reduction of the responses to both tones and noise components, was observed under some conditions, but overall reductions of BM vibration were rarely observed. Moderate- to high-intensity tones suppressed BM responses to low-intensity Gaussian stimuli, including both broadband and narrowband noise. Suppression effects were larger for spectral components of the noise response that were closer to the CF. In this regime, the tone and noise stimuli became the suppressor and probe signals, respectively. This study provides the first detailed observations of cochlear mechanical correlates of the masking effects of noise. Mechanical detection thresholds for tone signals, which were arbitrarily defined using three criteria, are shown to increase in almost direct proportion to the noise level for low and moderately high noise levels, in a manner that resembles the findings of numerous psychophysical observations. PMID:23478137

Cell-type specific short-term plasticity at auditory nerve synapses controls feed-forward inhibition in the dorsal cochlear nucleus.

PubMed

Sedlacek, Miloslav; Brenowitz, Stephan D

2014-01-01

Feed-forward inhibition (FFI) represents a powerful mechanism by which control of the timing and fidelity of action potentials in local synaptic circuits of various brain regions is achieved. In the cochlear nucleus, the auditory nerve provides excitation to both principal neurons and inhibitory interneurons. Here, we investigated the synaptic circuit associated with fusiform cells (FCs), principal neurons of the dorsal cochlear nucleus (DCN) that receive excitation from auditory nerve fibers and inhibition from tuberculoventral cells (TVCs) on their basal dendrites in the deep layer of DCN. Despite the importance of these inputs in regulating fusiform cell firing behavior, the mechanisms determining the balance of excitation and FFI in this circuit are not well understood. Therefore, we examined the timing and plasticity of auditory nerve driven FFI onto FCs. We find that in some FCs, excitatory and inhibitory components of FFI had the same stimulation thresholds indicating they could be triggered by activation of the same fibers. In other FCs, excitation and inhibition exhibit different stimulus thresholds, suggesting FCs and TVCs might be activated by different sets of fibers. In addition, we find that during repetitive activation, synapses formed by the auditory nerve onto TVCs and FCs exhibit distinct modes of short-term plasticity. Feed-forward inhibitory post-synaptic currents (IPSCs) in FCs exhibit short-term depression because of prominent synaptic depression at the auditory nerve-TVC synapse. Depression of this feedforward inhibitory input causes a shift in the balance of fusiform cell synaptic input towards greater excitation and suggests that fusiform cell spike output will be enhanced by physiological patterns of auditory nerve activity.

Clinical investigation of the Nucleus Slim Modiolar Electrode.

PubMed

Aschendorff, Antje; Briggs, Robert; Brademann, Goetz; Helbig, Silke; Hornung, Joachim; Lenarz, Thomas; Marx, Mathieu; Ramos, Angel; Stöver, Timo; Escudé, Bernard; James, Chris J

2017-01-01

The Nucleus CI532 cochlear implant incorporates a new precurved electrode array, i.e., the Slim Modiolar electrode (SME), which is designed to bring electrode contacts close to the medial wall of the cochlea while avoiding trauma due to scalar dislocation or contact with the lateral wall during insertion. The primary aim of this prospective study was to determine the final position of the electrode array in clinical cases as evaluated using flat-panel volume computed tomography. Forty-five adult candidates for unilateral cochlear implantation were recruited from 8 centers. Eleven surgeons attended a temporal bone workshop and received further training with a transparent plastic cochlear model just prior to the first surgery. Feedback on the surgical approach and use of the SME was collected via a questionnaire for each case. Computed tomography of the temporal bone was performed postoperatively using flat-panel digital volume tomography or cone beam systems. The primary measure was the final scalar position of the SME (completely in scala tympani or not). Secondly, medial-lateral position and insertion depth were evaluated. Forty-four subjects received a CI532. The SME was located completely in scala tympani for all subjects. Pure round window (44% of the cases), extended round window (22%), and inferior and/or anterior cochleostomy (34%) approaches were successful across surgeons and cases. The SME was generally positioned close to the modiolus. Overinsertion of the array past the first marker tended to push the basal contacts towards the lateral wall and served only to increase the insertion depth of the first electrode contact without increasing the insertion depth of the most apical electrode. Complications were limited to tip fold-overs encountered in 2 subjects; both were attributed to surgical error, with both reimplanted successfully. The new Nucleus CI532 cochlear implant with SME achieved the design goal of producing little or no trauma as indicated by consistent scala tympani placement. Surgeons should be carefully trained to use the new deployment method such that tip fold-overs and over insertion may be avoided. © 2017 S. Karger AG, Basel.

A physiological frequency-position map of the chinchilla cochlea.

PubMed

Müller, Marcus; Hoidis, Silvi; Smolders, Jean W T

2010-09-01

Accumulating evidence indicates that mammalian cochlear frequency-position maps (location of maximum vibration of the basilar membrane as a function of frequency) depend on the physiological condition of the inner ear. Cochlear damage desensitizes the ear, after the damage the original location of maximum vibration is tuned to a lower sound frequency. This suggests that frequency-position maps, derived from such desensitized ears, are shifted to lower frequencies, corresponding to a shift of the basilar membrane vibration pattern towards the base for a given stimulus frequency. To test this hypothesis, we re-mapped the cochlear frequency-position map in the chinchilla. We collected frequency-position data from chinchillas in normal physiological condition ("physiological map") and compared these to data previously established from sound overexposed ears ("anatomical map"). The characteristic frequency (CF) of neurons in the cochlear nucleus was determined. Horse-radish peroxidase (HRP) or biocytin (BCT) were injected iontophoretically to trace auditory nerve fibers towards their innervation site in the organ of Corti. The relationship between distance from the base (d, percent) and frequency (f, kHz) was described best by a simple exponential function: d = 61.2 - 42.2 x log(f). The slope of the function was 2.55 mm/octave. Compared to the "anatomical map", the "physiological map" was shifted by about 0.3 octaves to higher frequencies corresponding to a shift of the basilar membrane vibration pattern of 0.8 mm towards the apex for a given stimulus frequency. Our findings affirm that frequency-position maps in the mammalian cochlea depend on the condition of the inner ear. Damage-induced desensitization in mammalian inner ears results in similar shifts of CF (about 0.5 octaves) but different shifts of the maximum of the vibration pattern towards the base at given frequencies, dependent on the mapping constant of the species, longer basilar membranes showing a larger basal shift. Furthermore, the results substantiate the notion that "crowding" at lower frequencies appears to be a specialization rather than a general feature. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Cochlear microdialysis for quantification of dexamethasone and fluorescein entry into scala tympani during round window administration.

PubMed

Hahn, Hartmut; Kammerer, Bernd; DiMauro, Andre; Salt, Alec N; Plontke, Stefan K

2006-02-01

Before new drugs for the treatment of inner ear disorders can be studied in controlled clinical trials, it is important that their pharmacokinetics be established in inner ear fluids. Microdialysis allows drug levels to be measured in perilymph without the volume disturbances and potential cerebrospinal fluid contamination associated with fluid sampling. The aims of this study were to show: (i) that despite low recovery rates from miniature dialysis probes, significant amounts of drug are removed from small fluid compartments, (ii) that dialysis sampling artifacts can be accounted for using computer simulations and (iii) that microdialysis allows quantification of the entry rates through the round window membrane (RWM) into scala tympani (ST). Initial experiments used microdialysis probes in small compartments in vitro containing sodium fluorescein. Stable concentrations were observed in large compartments (1000 microl) but significant concentration declines were observed in smaller compartments (100, 10 and 5.6 microl) comparable to the size of the inner ear. Computer simulations of these experiments closely approximated the experimental data. In in vivo experiments, sodium fluorescein 10 mg/ml and dexamethasone-dihydrogen-phosphate disodium salt 8 mg/ml were simultaneously applied to the RWM of guinea pigs. Perilymph concentration in the basal turn of ST was monitored using microdialysis. The fluorescein concentration reached after 200 min application (585+/-527 microg/ml) was approximately twice that of dexamethasone phosphate (291+/-369 microg/ml). Substantial variation in concentrations was found between animals by approximately a factor of 34 for fluorescein and at least 41 for dexamethasone phosphate. This is, to a large extent, thought to be the result of the RWM permeability varying in different animals. It was not caused by substance analysis variations, because two different analytic methods were used and the concentration ratio between the two substances remained nearly constant across the experiments and because differences were apparent for the repeated samples obtained in each animal. Interpretation of the results using computer simulations allowed RWM permeability to be quantified. It also demonstrated, however, that cochlear clearance values could not be reliably obtained with microdialysis because of the significant contribution of dialysis to clearance. The observed interanimal variation, e.g., in RWM permeability, is likely to be clinically relevant to the local application of drugs in patients.

Cochlear Microdialysis for Quantification of Dexamethasone and Fluorescein Entry into Scala Tympani During Round Window Administration

PubMed Central

Hahn, Hartmut; Kammerer, Bernd; DiMauro, Andre; Salt, Alec N.; Plontke, Stefan K.

2006-01-01

Before new drugs for the treatment of inner ear disorders can be studied in controlled clinical trials, it is important that their pharmacokinetics be established in inner ear fluids. Microdialysis allows drug levels to be measured in perilymph without the volume disturbances and potential cerebrospinal fluid contamination associated with fluid sampling. The aims of this study were to show: (i) that despite low recovery rates from miniature dialysis probes, significant amounts of drug are removed from small fluid compartments, (ii) that dialysis sampling artifacts can be accounted for using computer simulations and (iii) that microdialysis allows quantification of the entry rates through the round window membrane (RWM) into scala tympani (ST). Initial experiments used microdialysis probes in small compartments in vitro containing sodium fluorescein. Stable concentrations were observed in large compartments (1000 μl) but significant concentration declines were observed in smaller compartments (100, 10 and 5.6 μl) comparable to the size of the inner ear. Computer simulations of these experiments closely approximated the experimental data. In in vivo experiments, sodium fluorescein 10 mg/ml and dexamethasone-dihydrogen-phosphate disodium salt 8 mg/ml were simultaneously applied to the RWM of guinea pigs. Perilymph concentration in the basal turn of ST was monitored using microdialysis. The fluorescein concentration reached after 200 min application (585 ± 527 μg/ml) was approximately twice that of dexamethasone phosphate (291 ± 369 μg/ml). Substantial variation in concentrations was found between animals by approximately a factor of 34 for fluorescein and at least 41 for dexamethasone phosphate. This is, to a large extent, thought to be the result of the RWM permeability varying in different animals. It was not caused by substance analysis variations, because two different analytic methods were used and the concentration ratio between the two substances remained nearly constant across the experiments and because differences were apparent for the repeated samples obtained in each animal. Interpretation of the results using computer simulations allowed RWM permeability to be quantified. It also demonstrated, however, that cochlear clearance values could not be reliably obtained with microdialysis because of the significant contribution of dialysis to clearance. The observed interanimal variation, e.g., in RWM permeability, is likely to be clinically relevant to the local application of drugs in patients. PMID:16442251

Visualization and functional testing of acetylcholine receptor-like molecules in cochlear outer hair cells.

PubMed

Plinkert, P K; Gitter, A H; Zimmermann, U; Kirchner, T; Tzartos, S; Zenner, H P

1990-02-01

The efferent nerve endings at outer hair cells (OHCs) have been suggested to regulate active mechanical processes in the cochlea. The discovery of acetylcholine (ACh)-producing and -degrading enzymes in these synapses gave rise to the speculation that ACh might be one of the efferent transmitters. However, there has as yet been no identification and characterization of any corresponding receptor in OHCs which is required for further clarification of this question. In the present paper existence, location and first characterization of acetylcholine receptors (AChRs) in OHCs are reported. Using two anti-AChR monoclonal antibodies, AChR epitopes were found forming a cup at the basal end of the OHCs opposite to the efferent nerve endings. Furthermore, the studied molecules could be shown to extend through the cell membrane. In addition, the denervated OHC AChR-epitopes seem to move by lateral diffusion. Application of Carbachol and ACh to the basal pole of OHCs induced a weak, reversible cell contraction. Pharmacological controls revealed, that hte motile responses were mediated by the AChRs.

The bony labyrinth of the middle Pleistocene Sima de los Huesos hominins (Sierra de Atapuerca, Spain).

PubMed

Quam, Rolf; Lorenzo, Carlos; Martínez, Ignacio; Gracia-Téllez, Ana; Arsuaga, Juan Luis

2016-01-01

We performed 3D virtual reconstructions based on CT scans to study the bony labyrinth morphology in 14 individuals from the large middle Pleistocene hominin sample from the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca in northern Spain. The Atapuerca (SH) hominins represent early members of the Neandertal clade and provide an opportunity to compare the data with the later in time Neandertals, as well as Pleistocene and recent humans more broadly. The Atapuerca (SH) hominins do not differ from the Neandertals in any of the variables related to the absolute and relative sizes and shape of the semicircular canals. Indeed, the entire Neandertal clade seems to be characterized by a derived pattern of canal proportions, including a relatively small posterior canal and a relatively large lateral canal. In contrast, one of the most distinctive features observed in Neandertals, the low placement of the posterior canal (i.e., high sagittal labyrinthine index), is generally not present in the Atapuerca (SH) hominins. This low placement is considered a derived feature in Neandertals and is correlated with a more vertical orientation of the ampullar line (LSCm < APA), posterior surface of the petrous pyramid (LSCm > PPp), and third part of the facial canal (LSCm < FC3). Some variation is present within the Atapuerca (SH) sample, however, with a few individuals approaching the Neandertal condition more closely. In addition, the cochlear shape index in the Atapuerca (SH) hominins is low, indicating a reduction in the height of the cochlea. Although the phylogenetic polarity of this feature is less clear, the low shape index in the Atapuerca (SH) hominins may be a derived feature. Regardless, cochlear height subsequently increased in Neandertals. In contrast to previous suggestions, the expanded data in the present study indicate no difference across the genus Homo in the angle of inclination of the cochlear basal turn (COs < LSCm). Principal components analysis largely confirms these observations. While not fully resolved, the low placement of the posterior canal in Neandertals may be related to some combination of absolutely large brain size, a wide cranial base, and an archaic pattern of brain allometry. This more general explanation would not necessarily follow taxonomic lines, even though this morphology of the bony labyrinth occurs at high frequencies among Neandertals. While a functional interpretation of the relatively small vertical canals in the Neandertal clade remains elusive, the relative proportions of the semicircular canals is one of several derived Neandertal features in the Atapuerca (SH) crania. Examination of additional European middle Pleistocene specimens suggests that the full suite of Neandertal features in the bony labyrinth did not emerge in Europe until perhaps <200 kya. Copyright © 2015 Elsevier Ltd. All rights reserved.

Place specificity of monopolar and tripolar stimuli in cochlear implants: the influence of residual masking.

PubMed

Fielden, Claire A; Kluk, Karolina; McKay, Colette M

2013-06-01

This experiment investigated whether place specificity of neural activity evoked by cochlear implant stimulation is improved in tripolar compared to monopolar mode using a forward masking protocol addressing some limitations of previous methods of measurement and analysis. The amount of residual masking (masking remaining at long masker-probe delays) was also measured, and its potential influence on the specificity measures was evaluated. The masker stimulus comprised equally loud interleaved mono- or tripolar stimulation on two electrodes equidistant from a central probe electrode in an apical and basal direction, reducing the influence of off-site listening. The effect of masker-probe distance on the threshold shift of the tripolar probe was analyzed to derive a measure of place specificity. On average, tripolar maskers were more place specific than monopolar maskers, although the mean effect was small. There was no significant effect of masker level on specificity or on the differences observed between modes. The mean influence of residual masking on normalized masking functions was similar for the two modes and, therefore, did not influence the comparison of specificity between the modes. However, variability in amount of residual masking was observed between subjects, and therefore should be considered in forward masking studies that compare place specificity across subjects.

Effects of stimulation configurations on place pitch discrimination in cochlear implants.

PubMed

Kwon, Bomjun J; Perry, Trevor T; Olmstead, Vauna L

2011-06-01

The present study aimed to examine the effect of electrode configuration, specifically monopolar (MP) or bipolar (BP) stimulation, on place pitch discrimination in cochlear implants (CIs). Twelve subjects implanted with the Nucleus Freedom device were presented with various pairs of stimulation across the electrode array, with varying degrees of distance between stimulation sites, and asked to judge the higher of the two in pitch. Each pair was presented either in the same mode or in different modes of stimulation for the within-mode or across-mode condition, respectively, at least 20 times. The result of the within-mode condition revealed that subjects, on average, were able to discriminate pitches significantly better in MP than in BP, with the sensitivity index (d') for adjacent channels of 1.2 for MP and 0.8 for BP. The result of the across-mode condition revealed that while individual variability existed, there was a strong tendency for CI subjects to perceive a higher pitch in BP stimulation than in MP for a similar site of stimulation. In other words, an MP channel needed to be shifted in a basal direction by as much as two electrodes on average to elicit a pitch comparable to that of a BP channel. © 2011 Acoustical Society of America

Effects of cochlear-implant pulse rate and inter-channel timing on channel interactions and thresholds

NASA Astrophysics Data System (ADS)

Middlebrooks, John C.

2004-07-01

Interactions among the multiple channels of a cochlear prosthesis limit the number of channels of information that can be transmitted to the brain. This study explored the influence on channel interactions of electrical pulse rates and temporal offsets between channels. Anesthetized guinea pigs were implanted with 2-channel scala-tympani electrode arrays, and spike activity was recorded from the auditory cortex. Channel interactions were quantified as the reduction of the threshold for pulse-train stimulation of the apical channel by sub-threshold stimulation of the basal channel. Pulse rates were 254 or 4069 pulses per second (pps) per channel. Maximum threshold reductions averaged 9.6 dB when channels were stimulated simultaneously. Among nonsimultaneous conditions, threshold reductions at the 254-pps rate were entirely eliminated by a 1966-μs inter-channel offset. When offsets were only 41 to 123 μs, however, maximum threshold shifts averaged 3.1 dB, which was comparable to the dynamic ranges of cortical neurons in this experimental preparation. Threshold reductions at 4069 pps averaged up to 1.3 dB greater than at 254 pps, which raises some concern in regard to high-pulse-rate speech processors. Thresholds for various paired-pulse stimuli, pulse rates, and pulse-train durations were measured to test possible mechanisms of temporal integration.

Intensity coding in electric hearing: Effects of electrode configurations and stimulation waveforms

PubMed Central

Chua, Tiffany Elise H.; Bachman, Mark; Zeng, Fan-Gang

2011-01-01

Objectives Current cochlear implants typically stimulate the auditory nerve with biphasic pulses and monopolar electrode configurations. Tripolar stimulation can increase spatial selectivity and potentially improve place pitch related perception, but requires higher current levels to elicit the same loudness as monopolar stimulation. The present study combined delayed pseudomonophonasic pulses, which produce lower thresholds, with tripolar stimulation in an attempt to solve the power-performance tradeoff problem. Design The present study systematically measured thresholds, dynamic range, loudness growth, and intensity discrimination using either biphasic or delayed pseudomonophonasic pulses under both monopolar and tripolar stimulation. Participants were 5 Clarion cochlear implant users. For each subject, data from apical, middle and basal electrode positions were collected when possible. Results Compared with biphasic pulses, delayed pseudomonophonasic pulses increased the dynamic range by lowering thresholds while maintaining comparable maximum allowable levels under both electrode configurations. However, delayed pseudomonophonasic pulses did not change the shape of loudness growth function and actually increased intensity discrimination limens, especially at lower current levels. Conclusions The present results indicate that delayed pseudomonophonasic pulses coupled with tripolar stimulation cannot provide significant power savings, nor can it increase the functional dynamic range. Whether this combined stimulation could improve functional spectral resolution remains to be seen. PMID:21610498

Ultrastructure of the Odontocete organ of Corti: scanning and transmission electron microscopy.

PubMed

Morell, Maria; Lenoir, Marc; Shadwick, Robert E; Jauniaux, Thierry; Dabin, Willy; Begeman, Lineke; Ferreira, Marisa; Maestre, Iranzu; Degollada, Eduard; Hernandez-Milian, Gema; Cazevieille, Chantal; Fortuño, José-Manuel; Vogl, Wayne; Puel, Jean-Luc; André, Michel

2015-02-15

The morphological study of the Odontocete organ of Corti, together with possible alterations associated with damage from sound exposure, represents a key conservation approach to assess the effects of acoustic pollution on marine ecosystems. By collaborating with stranding networks from several European countries, 150 ears from 13 species of Odontocetes were collected and analyzed by scanning (SEM) and transmission (TEM) electron microscopy. Based on our analyses, we first describe and compare Odontocete cochlear structures and then propose a diagnostic method to identify inner ear alterations in stranded individuals. The two species analyzed by TEM (Phocoena phocoena and Stenella coeruleoalba) showed morphological characteristics in the lower basal turn of high-frequency hearing species. Among other striking features, outer hair cell bodies were extremely small and were strongly attached to Deiters cells. Such morphological characteristics, shared with horseshoe bats, suggest that there has been convergent evolution of sound reception mechanisms among echolocating species. Despite possible autolytic artifacts due to technical and experimental constraints, the SEM analysis allowed us to detect the presence of scarring processes resulting from the disappearance of outer hair cells from the epithelium. In addition, in contrast to the rapid decomposition process of the sensory epithelium after death (especially of the inner hair cells), the tectorial membrane appeared to be more resistant to postmortem autolysis effects. Analysis of the stereocilia imprint pattern at the undersurface of the tectorial membrane may provide a way to detect possible ultrastructural alterations of the hair cell stereocilia by mirroring them on the tectorial membrane. © 2014 Wiley Periodicals, Inc.

The spatial and temporal representation of a tone on the guinea pig basilar membrane

NASA Astrophysics Data System (ADS)

Nilsen, K. E.; Russell, I. J.

2000-10-01

School of Biological Sciences, University of Sussex, Falmer Brighton, BN1 9QG, United Kingdom In the mammalian cochlea, the basilar membrane's (BM) mechanical responses are amplified, and frequency tuning is sharpened through active feedback from the electromotile outer hair cells (OHCs). To be effective, OHC feedback must be delivered to the correct region of the BM and introduced at the appropriate time in each cycle of BM displacement. To investigate when OHCs contribute to cochlear amplification, a laser-diode interferometer was used to measure tone-evoked BM displacements in the basal turn of the guinea pig cochlea. Measurements were made at multiple sites acrossthe width of the BM, which are tuned to the same characteristic frequency (CF). In response to CF tones, the largest displacements occur in the OHC region and phase lead those measured beneath the outer pillar cells and adjacent to the spiral ligament by about 90°. Postmortem, responses beneath the OHCs are reduced by up to 65 dB, and all regions across the width of the BM move in unison. We suggest that OHCs amplify BM responses to CF tones when the BM is moving at maximum velocity. In regions of the BM where OHCs contribute to its motion, the responses are compressive and nonlinear. We measured the distribution of nonlinear compressive vibrations along the length of the BM in response to a single frequency tone and estimated that OHC amplification is restricted to a 1.25- to 1.40-mm length of BM centered on the CF place.

Relationship Between Peripheral and Psychophysical Measures of Amplitude Modulation Detection in Cochlear Implant Users.

PubMed

Tejani, Viral D; Abbas, Paul J; Brown, Carolyn J

This study investigates the relationship between electrophysiological and psychophysical measures of amplitude modulation (AM) detection. Prior studies have reported both measures of AM detection recorded separately from cochlear implant (CI) users and acutely deafened animals, but no study has made both measures in the same CI users. Animal studies suggest a progressive loss of high-frequency encoding as one ascends the auditory pathway from the auditory nerve to the cortex. Because the CI speech processor uses the envelope of an ongoing acoustic signal to modulate pulse trains that are subsequently delivered to the intracochlear electrodes, it is of interest to explore auditory nerve responses to modulated stimuli. In addition, psychophysical AM detection abilities have been correlated with speech perception outcomes. Thus, the goal was to explore how the auditory nerve responds to AM stimuli and to relate those physiologic measures to perception. Eight patients using Cochlear Ltd. Implants participated in this study. Electrically evoked compound action potentials (ECAPs) were recorded using a 4000 pps pulse train that was sinusoidally amplitude modulated at 125, 250, 500, and 1000 Hz rates. Responses were measured for each pulse over at least one modulation cycle for an apical, medial, and basal electrode. Psychophysical modulation detection thresholds (MDTs) were also measured via a three-alternative forced choice, two-down, one-up adaptive procedure using the same modulation frequencies and electrodes. ECAPs were recorded from individual pulses in the AM pulse train. ECAP amplitudes varied sinusoidally, reflecting the sinusoidal variation in the stimulus. A modulated response amplitude (MRA) metric was calculated as the difference in the maximal and minimum ECAP amplitudes over the modulation cycles. MRA increased as modulation frequency increased, with no apparent cutoff (up to 1000 Hz). In contrast, MDTs increased as the modulation frequency increased. This trend is inconsistent with the physiologic measures. For a fixed modulation frequency, correlations were observed between MDTs and MRAs; this trend was evident at all frequencies except 1000 Hz (although only statistically significant for 250 and 500 Hz AM rates), possibly an indication of central limitations in processing of high modulation frequencies. Finally, peripheral responses were larger and psychophysical thresholds were lower in the apical electrodes relative to basal and medial electrodes, which may reflect better cochlear health and neural survival evidenced by lower preoperative low-frequency audiometric thresholds and steeper growth of neural responses in ECAP amplitude growth functions for apical electrodes. Robust ECAPs were recorded for all modulation frequencies tested. ECAP amplitudes varied sinusoidally, reflecting the periodicity of the modulated stimuli. MRAs increased as the modulation frequency increased, a trend we attribute to neural adaptation. For low modulation frequencies, there are multiple current steps between the peak and valley of the modulation cycle, which means successive stimuli are more similar to one another and neural responses are more likely to adapt. Higher MRAs were correlated with lower psychophysical thresholds at low modulation frequencies but not at 1000 Hz, implying a central limitation to processing of modulated stimuli.

Prosody perception and musical pitch discrimination in adults using cochlear implants.

PubMed

Kalathottukaren, Rose Thomas; Purdy, Suzanne C; Ballard, Elaine

2015-07-01

This study investigated prosodic perception and musical pitch discrimination in adults using cochlear implants (CI), and examined the relationship between prosody perception scores and non-linguistic auditory measures, demographic variables, and speech recognition scores. Participants were given four subtests of the PEPS-C (profiling elements of prosody in speech-communication), the adult paralanguage subtest of the DANVA 2 (diagnostic analysis of non verbal accuracy 2), and the contour and interval subtests of the MBEA (Montreal battery of evaluation of amusia). Twelve CI users aged 25;5 to 78;0 years participated. CI participants performed significantly more poorly than normative values for New Zealand adults for PEPS-C turn-end, affect, and contrastive stress reception subtests, but were not different from the norm for the chunking reception subtest. Performance on the DANVA 2 adult paralanguage subtest was lower than the normative mean reported by Saindon (2010) . Most of the CI participants performed at chance level on both MBEA subtests. CI users have difficulty perceiving prosodic information accurately. Difficulty in understanding different aspects of prosody and music may be associated with reduced pitch perception ability.

Effects of surgical lesions on choline acetyltransferase activity in the cat cochlea.

PubMed

Frilling, Mark J; Wiet, Gregory J; Godfrey, Donald A; Parli, Judy A; Dunn, Jon D; Ross, C David

2017-12-01

Although it is well established that the choline acetyltransferase (ChAT, the enzyme for acetylcholine synthesis) in the mammalian cochlea is associated with its olivocochlear innervation, the distribution of this innervation in the cochlea varies somewhat among mammalian species. The quantitative distribution of ChAT activity in the cochlea has been reported for guinea pigs and rats. The present study reports the distribution of ChAT activity within the organ of Corti among the three turns of the cat cochlea and the effects of removing olivocochlear innervation either by a lateral cut aimed to totally transect the left olivocochlear bundle or a more medial cut additionally damaging the superior olivary complex on the same side. Similarly to results for guinea pig and rat, the distribution of ChAT activity in the cat outer hair cell region showed a decrease from base to apex, but, unlike in the guinea pig and rat, the cat inner hair cell region did not. As in the rat, little ChAT activity was measured in the outer supporting cell region. As previously reported for whole cat cochlea and for rat cochlear regions, transection of the olivocochlear bundle resulted in almost total loss of ChAT activity in the hair cell regions of the cat cochlea. Lesions of the superior olivary complex resulted in loss of ChAT activity in the inner hair cell region of all cochlear turns only on the lesion side but bilateral losses in the outer hair cell region of all turns. The results are consistent with previous evidence that virtually all cholinergic synapses in the mammalian cochlea are associated with its olivocochlear innervation, that the olivocochlear innervation to the inner hair cell region is predominantly ipsilateral, and that the olivocochlear innervation to the outer hair cells is bilateral. Copyright © 2017 Elsevier B.V. All rights reserved.

New Criteria of Indication and Selection of Patients to Cochlear Implant

PubMed Central

Sampaio, André L. L.; Araújo, Mercêdes F. S.; Oliveira, Carlos A. C. P.

2011-01-01

Numerous changes continue to occur in cochlear implant candidacy. In general, these have been accompanied by concomitant and satisfactory changes in surgical techniques. Together, this has advanced the utility and safety of cochlear implantation. Most devices are now approved for use in patients with severe to profound unilateral hearing loss rather then the prior requirement of a bilateral profound loss. Furthermore, studies have begun utilizing short electrode arrays for shallow insertion in patients with considerable low-frequency residual hearing. This technique will allow the recipient to continue to use acoustically amplified hearing for the low frequencies simultaneously with a cochlear implant for the high frequencies. The advances in design of, and indications for, cochlear implants have been matched by improvements in surgical techniques and decrease in complications. The resulting improvements in safety and efficacy have further encouraged the use of these devices. This paper will review the new concepts in the candidacy of cochlear implant. Medline data base was used to search articles dealing with the following topics: cochlear implant in younger children, cochlear implant and hearing preservation, cochlear implant for unilateral deafness and tinnitus, genetic hearing loss and cochlear implant, bilateral cochlear implant, neuropathy and cochlear implant and neural plasticity, and the selection of patients for cochlear implant. PMID:22013448

Cochlear Implants.

ERIC Educational Resources Information Center

Clark, Catherine; Scott, Larry

This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

Reduction of eddy current losses in inductive transmission systems with ferrite sheets.

PubMed

Maaß, Matthias; Griessner, Andreas; Steixner, Viktor; Zierhofer, Clemens

2017-01-05

Improvements in eddy current suppression are necessary to meet the demand for increasing miniaturization of inductively driven transmission systems in industrial and biomedical applications. The high magnetic permeability and the simultaneously low electrical conductivity of ferrite materials make them ideal candidates for shielding metallic surfaces. For systems like cochlear implants the transmission of data as well as energy over an inductive link is conducted within a well-defined parameter set. For these systems, the shielding can be of particular importance if the properties of the link can be preserved. In this work, we investigate the effect of single and double-layered substrates consisting of ferrite and/or copper on the inductance and coupling of planar spiral coils. The examined link systems represent realistic configurations for active implantable systems such as cochlear implants. Experimental measurements are complemented with analytical calculations and finite element simulations, which are in good agreement for all measured parameters. The results are then used to study the transfer efficiency of an inductive link in a series-parallel resonant topology as a function of substrate size, the number of coil turns and coil separation. We find that ferrite sheets can be used to shield the system from unwanted metallic surfaces and to retain the inductive link parameters of the unperturbed system, particularly its transfer efficiency. The required size of the ferrite plates is comparable to the size of the coils, which makes the setup suitable for practical implementations. Since the sizes and geometries chosen for the studied inductive links are comparable to those of cochlear implants, our conclusions apply in particular to these systems.

Ipsilateral masking between acoustic and electric stimulations.

PubMed

Lin, Payton; Turner, Christopher W; Gantz, Bruce J; Djalilian, Hamid R; Zeng, Fan-Gang

2011-08-01

Residual acoustic hearing can be preserved in the same ear following cochlear implantation with minimally traumatic surgical techniques and short-electrode arrays. The combined electric-acoustic stimulation significantly improves cochlear implant performance, particularly speech recognition in noise. The present study measures simultaneous masking by electric pulses on acoustic pure tones, or vice versa, to investigate electric-acoustic interactions and their underlying psychophysical mechanisms. Six subjects, with acoustic hearing preserved at low frequencies in their implanted ear, participated in the study. One subject had a fully inserted 24 mm Nucleus Freedom array and five subjects had Iowa/Nucleus hybrid implants that were only 10 mm in length. Electric masking data of the long-electrode subject showed that stimulation from the most apical electrodes produced threshold elevations over 10 dB for 500, 625, and 750 Hz probe tones, but no elevation for 125 and 250 Hz tones. On the contrary, electric stimulation did not produce any electric masking in the short-electrode subjects. In the acoustic masking experiment, 125-750 Hz pure tones were used to acoustically mask electric stimulation. The acoustic masking results showed that, independent of pure tone frequency, both long- and short-electrode subjects showed threshold elevations at apical and basal electrodes. The present results can be interpreted in terms of underlying physiological mechanisms related to either place-dependent peripheral masking or place-independent central masking.

Localization of the calcium channel subunits Cav1.2 (alpha1C) and Cav2.3 (alpha1E) in the mouse organ of Corti.

PubMed

Waka, N; Knipper, M; Engel, J

2003-10-01

Voltage-activated Ca2+ channels play an important role in synaptic transmission, signal processing and development. The immunohistochemical localization of Cav1.2 (alpha1C) and Cav2.3 (alpha1E) Ca2+ channels was studied in the developing and adult mouse organ of Corti using subunit-specific antibodies and fluorescent secondary antibodies with cochlear cryosections. Cav1.2 immunoreactivity has been detected from postnatal day 14 (P14) onwards at the synapses between cholinergic medial efferents and outer hair cells as revealed by co-staining with anti-synaptophysin and anti-choline acetyltransferase. Most likely the Cav1.2 immunoreactivity was located presynaptically at the site of contact of the efferent bouton with the outer hair cell which suggests a role for class C L-type Ca2+ channels in synaptic transmission of the medial efferent system. The localization of the second Ca2+ channel tested, Cav2.3, showed a pronounced change during cochlear development. From P2 until P10, Cav2.3 immunoreactivity was found in the outer spiral bundle followed by the inner spiral bundle, efferent endings and by medial efferent fibers. Around P14, Cav2.3 immunoreactivity disappeared from these structures and from P19 onwards it was observed in the basal poles of the outer hair cell membranes.

Auditory hair cell centrioles undergo confined Brownian motion throughout the developmental migration of the kinocilium.

PubMed

Lepelletier, Léa; de Monvel, Jacques Boutet; Buisson, Johanna; Desdouets, Chantal; Petit, Christine

2013-07-02

Planar polarization of the forming hair bundle, the mechanosensory antenna of auditory hair cells, depends on the poorly characterized center-to-edge displacement of a primary cilium, the kinocilium, at their apical surface. Taking advantage of the gradient of hair cell differentiation along the cochlea, we reconstituted a map of the kinocilia displacements in the mouse embryonic cochlea. We then developed a cochlear organotypic culture and video-microscopy approach to monitor the movements of the kinocilium basal body (mother centriole) and its daughter centriole, which we analyzed using particle tracking and modeling. We found that both hair cell centrioles undergo confined Brownian movements around their equilibrium positions, under the apparent constraint of a radial restoring force of ∼0.1 pN. This magnitude depended little on centriole position, suggesting nonlinear interactions with constraining, presumably cytoskeletal elements. The only dynamic change observed during the period of kinocilium migration was a doubling of the centrioles' confinement area taking place early in the process. It emerges from these static and dynamic observations that kinocilia migrate gradually in parallel with the organization of hair cells into rows during cochlear neuroepithelium extension. Analysis of the confined motion of hair cell centrioles under normal and pathological conditions should help determine which structures contribute to the restoring force exerting on them. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

The role of N-methyl-D-aspartate receptors and nitric oxide in cochlear dopamine release.

PubMed

Halmos, G; Horváth, T; Polony, G; Fekete, A; Kittel, A; Vizi, E S; van der Laan, B F A M; Zelles, T; Lendvai, B

2008-06-23

Dopamine (DA) released from lateral olivocochlear (LOC) terminals may have a neuroprotective effect in the cochlea. To explore the role of N-methyl-d-aspartate (NMDA) receptors and nitric oxide (NO) in the modulation of a cochlear DA release, we measured the release of [3H]DA from isolated mouse cochlea in response to the application of NMDA. NMDA at 100 muM significantly increased the electrical-field stimulation-evoked and resting release of DA from the cochlea. The NO donor sodium nitroprusside enhanced the basal outflow of DA but failed to influence the evoked release. The administration of the nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) alone was ineffective, but it significantly inhibited the initial phase of the NMDA-induced elevation of DA outflow, which suggested the role of NO in the NMDA-induced DA release. The DA uptake inhibitor nomifensine increased the electrically evoked release of DA. Nomifensine failed to change the effect of NMDA on the resting or electrically-evoked DA release, which suggested that the uptake mechanism does not play a role in NMDA-evoked and NO-mediated DA release. In summary, we provide evidence that NO can modulate the release of DA from the cochlea following NMDA receptor activation, but does not affect the uptake of DA.

Auditory Hair Cell Centrioles Undergo Confined Brownian Motion Throughout the Developmental Migration of the Kinocilium

PubMed Central

Lepelletier, Léa; de Monvel, Jacques Boutet; Buisson, Johanna; Desdouets, Chantal; Petit, Christine

2013-01-01

Planar polarization of the forming hair bundle, the mechanosensory antenna of auditory hair cells, depends on the poorly characterized center-to-edge displacement of a primary cilium, the kinocilium, at their apical surface. Taking advantage of the gradient of hair cell differentiation along the cochlea, we reconstituted a map of the kinocilia displacements in the mouse embryonic cochlea. We then developed a cochlear organotypic culture and video-microscopy approach to monitor the movements of the kinocilium basal body (mother centriole) and its daughter centriole, which we analyzed using particle tracking and modeling. We found that both hair cell centrioles undergo confined Brownian movements around their equilibrium positions, under the apparent constraint of a radial restoring force of ∼0.1 pN. This magnitude depended little on centriole position, suggesting nonlinear interactions with constraining, presumably cytoskeletal elements. The only dynamic change observed during the period of kinocilium migration was a doubling of the centrioles’ confinement area taking place early in the process. It emerges from these static and dynamic observations that kinocilia migrate gradually in parallel with the organization of hair cells into rows during cochlear neuroepithelium extension. Analysis of the confined motion of hair cell centrioles under normal and pathological conditions should help determine which structures contribute to the restoring force exerting on them. PMID:23823223

Two dimensional vibrations of the guinea pig apex organ of Corti measured in vivo using phase sensitive Fourier domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Ramamoorthy, Sripriya; Zhang, Yuan; Petrie, Tracy; Fridberger, Anders; Ren, Tianying; Wang, Ruikang; Jacques, Steven L.; Nuttall, Alfred L.

2015-02-01

In this study, we measure the in vivo apical-turn vibrations of the guinea pig organ of Corti in both axial and radial directions using phase-sensitive Fourier domain optical coherence tomography. The apical turn in guinea pig cochlea has best frequencies around 100 - 500 Hz which are relevant for human speech. Prior measurements of vibrations in the guinea pig apex involved opening the otic capsule, which has been questioned on the basis of the resulting changes to cochlear hydrodynamics. Here this limitation is overcome by measuring the vibrations through bone without opening the otic capsule. Furthermore, we have significantly reduced the surgery needed to access the guinea pig apex in the axial direction by introducing a miniature mirror inside the bulla. The method and preliminary data are discussed in this article.

The Effect of Superior Semicircular Canal Dehiscence on Intracochlear Sound Pressures

PubMed Central

Pisano, Dominic V.; Niesten, Marlien E.F.; Merchant, Saumil N.; Nakajima, Hideko Heidi

2013-01-01

Semicircular canal dehiscence (SCD) is a pathological opening in the bony wall of the inner ear that can result in conductive hearing loss. The hearing loss is variable across patients, and the precise mechanism and source of variability are not fully understood. Simultaneous measurements of basal intracochlear sound pressures in scala vestibuli (SV) and scala tympani (ST) enable quantification of the differential pressure across the cochlear partition, the stimulus that excites the cochlear partition. We used intracochlear sound pressure measurements in cadaveric preparations to study the effects of SCD size. Sound-induced pressures in SV and ST, as well as stapes velocity and ear-canal pressure were measured simultaneously for various sizes of SCD followed by SCD patching. Our results showed that at low frequencies (<600 Hz), SCD decreased the pressure in both SV and ST, as well as differential pressure, and these effects became more pronounced as dehiscence size was increased. Near 100 Hz, SV decreased about 10 dB for a 0.5 mm dehiscence and 20 dB for a 2 mm dehiscence, while ST decreased about 8 dB for a 0.5 mm dehiscence and 18 dB for a 2mm dehiscence. Differential pressure decreased about 10 dB for a 0.5 mm dehiscence and about 20 dB for a 2 mm dehiscense at 100 Hz. In some ears, for frequencies above 1 kHz, the smallest pinpoint dehiscence had bigger effects on the differential pressure (10 dB decrease) than larger dehiscenses (less than 10 dB decrease), suggesting larger hearing losses in this frequency range. These effects due to SCD were reversible by patching the dehiscence. We also showed that under certain circumstances such as SCD, stapes velocity is not related to how the ear can transduce sound across the cochlear partition because it is not directly related to the differential pressure, emphasizing that certain pathologies cannot be fully assessed by measurements such as stapes velocity. PMID:22814034

Plasticity after pediatric cochlear implantation: Implication from changes in peripheral plasma level of BDNF and auditory nerve responses.

PubMed

Alemi, Razieh; Motassadi Zarandy, Masoud; Joghataei, Mohammad Taghi; Eftekharian, Ali; Zarrindast, Mohammad Reza; Vousooghi, Nasim

2018-02-01

Sensory neural hearing loss could lead to some structural and physiological changes in the auditory pathways, such as alteration in the expression of neurotrophins. These factors, especially Brain-Derived Neurotrophic Factor (BDNF), play an important role in synaptic functions and experience-related plasticity. Restoring cochlear function after hearing loss is possible through cochlear implantation (CI). Evaluation of the blood concentration changes of neurotrophins as prerequisites of plasticity could help scientists to determine the prognosis of CI as in the candidacy procedure or enhancing prosthesis function by adding the exact needed amount of BDNF to the electrode array. Here we have studied the plasma BDNF concentration before CI surgery and 6 months after using CI device in 15 pediatric CI recipients and compared this level with changes of BDNF concentration in 10 children who were using hearing aid (H.A). In addition, we searched for a possible correlation between post-surgery plasma BDNF concentration and electrical compound action potential (ECAP) and comfort-level (C-level) thresholds. Plasma BDNF concentration in children with CI increased significantly after CI surgery, while this difference in H.A group was not significant. Analysis of repeated measures of ECAP and C-level thresholds in CI group showed that there were some kinds of steadiness during follow- up sessions for ECAP thresholds in basal and E16 of middle electrodes, whereas C-level thresholds for all selected electrodes increased significantly up to six months follow-up. Interestingly, we did not find any significant correlation between post-surgery plasma BDNF concentration and ECAP or C-level threshold changes. It is concluded that changes in C-level threshold and steady state of ECAP thresholds and significant changes in BDNF concentration could be regarded as an indicator of experienced-related plasticity after CI stimulation. Copyright © 2017 Elsevier B.V. All rights reserved.

[Inspecting the cochlear scala tympanic with flexible and semi-flexible micro-endoscope].

PubMed

Zhang, Daoxcing; Zhang, Yankun

2006-02-01

Flexible and semi-flexible micro-endoscopes were used in cochlear scala tympani inspection , to explore their application in inner ear examination. Fifteen profound hearing loss patients preparing for cochlear implant were included in this study. During the operation, micro-endoscopy was performed after opening the cochlear scala tympani. And 1 mm diameter semi-flexible micro-endoscope could go as deep as 9 mm into the cochlear scala tympani, while 0. 5 mm diameter flexible micro-endoscope could go as deep as 25 mm. The inspecting results were compared with video recording. Using 0.5 mm flexible micro-endoscope, we canould check cochlear scala tympani with depth range of 15-25 mm, but the video imaging was not clear enough to examine the microstructure in the cochlear. With 1 mm diameter semi-flexible micro-endoscope, we could reach 9 mm deep into the cochlear. During the examination, we found 3 cases with calcification deposit in osseous spiral lamina, l case with granulation tissue in the lateral wall of scala tympani, no abnormal findings in the other 11 cases. Inspecting the cochlear scala tympani with 0.5 mm flexible micro-endoscope, even though we can reach the second circuit of the cochlear, it is difficult to find the pathology in the cochlear because of the poor video imaging. With 1 mm semi-flexible micro-endoscope, we can identify the microstructure of the cochlear clearly and find the pathologic changes, but the inserting depth was limited to 9 mm with limitation to examine the whole cochlear.

What Does Music Sound Like for a Cochlear Implant User?

PubMed

Jiam, Nicole T; Caldwell, Meredith T; Limb, Charles J

2017-09-01

Cochlear implant research and product development over the past 40 years have been heavily focused on speech comprehension with little emphasis on music listening and enjoyment. The relatively little understanding of how music sounds in a cochlear implant user stands in stark contrast to the overall degree of importance the public places on music and quality of life. The purpose of this article is to describe what music sounds like to cochlear implant users, using a combination of existing research studies and listener descriptions. We examined the published literature on music perception in cochlear implant users, particularly postlingual cochlear implant users, with an emphasis on the primary elements of music and recorded music. Additionally, we administered an informal survey to cochlear implant users to gather first-hand descriptions of music listening experience and satisfaction from the cochlear implant population. Limitations in cochlear implant technology lead to a music listening experience that is significantly distorted compared with that of normal hearing listeners. On the basis of many studies and sources, we describe how music is frequently perceived as out-of-tune, dissonant, indistinct, emotionless, and weak in bass frequencies, especially for postlingual cochlear implant users-which may in part explain why music enjoyment and participation levels are lower after implantation. Additionally, cochlear implant users report difficulty in specific musical contexts based on factors including but not limited to genre, presence of lyrics, timbres (woodwinds, brass, instrument families), and complexity of the perceived music. Future research and cochlear implant development should target these areas as parameters for improvement in cochlear implant-mediated music perception.

Progress in Cochlear Physiology after Békésy

PubMed Central

Guinan, John J.; Salt, Alec; Cheatham, Mary Ann

2012-01-01

In the fifty years since Békésy was awarded the Nobel Prize, cochlear physiology has blossomed. Many topics that are now current are things Békésy could not have imagined. In this review we start by describing progress in understanding the origin of cochlear gross potentials, particularly the cochlear microphonic, an area in which Békésy had extensive experience. We then review progress in areas of cochlear physiology that were mostly unknown to Békésy, including: (1) stereocilia mechano-electrical transduction, force production, and response amplification, (2) outer hair cell (OHC) somatic motility and its molecular basis in prestin, (3) cochlear amplification and related micromechanics, including the evidence that prestin is the main motor for cochlear amplification, (4) the influence of the tectorial membrane, (5) cochlear micromechanics and the mechanical drives to inner hair cell stereocilia, (6) otoacoustic emissions, and (7) olivocochlear efferents and their influence on cochlear physiology. We then return to a subject that Békésy knew well: cochlear fluids and standing currents, as well as our present understanding of energy dependence on the lateral wall of the cochlea. Finally, we touch on cochlear pathologies including noise damage and aging, with an emphasis on where the field might go in the future. PMID:22633944

Dynamic expression of Lgr6 in the developing and mature mouse cochlea

PubMed Central

Zhang, Yanping; Chen, Yan; Ni, Wenli; Guo, Luo; Lu, Xiaoling; Liu, Liman; Li, Wen; Sun, Shan; Wang, Lei; Li, Huawei

2015-01-01

The Wnt/β-catenin signaling pathway plays important roles in mammalian inner ear development. Lgr5, one of the downstream target genes of the Wnt/β-catenin signaling pathway, has been reported to be a marker for inner ear hair cell progenitors. Lgr6 shares approximately 50% sequence homology with Lgr5 and has been identified as a stem cell marker in several organs. However, the detailed expression profiles of Lgr6 have not yet been investigated in the mouse inner ear. Here, we first used Lgr6-EGFP-Ires-CreERT2 mice to examine the spatiotemporal expression of Lgr6 protein in the cochlear duct during embryonic and postnatal development. Lgr6-EGFP was first observed in one row of prosensory cells in the middle and basal turn at embryonic day 15.5 (E15.5). From E18.5 to postnatal day 3 (P3), the expression of Lgr6-EGFP was restricted to the inner pillar cells (IPCs). From P7 to P15, the Lgr6-EGFP expression level gradually decreased in the IPCs and gradually increased in the inner border cells (IBCs). At P20, Lgr6-EGFP was only expressed in the IBCs, and by P30 Lgr6-EGFP expression had completely disappeared. Next, we demonstrated that Wnt/β-catenin signaling is required to maintain the Lgr6-EGFP expression in vitro. Finally, we demonstrated that the Lgr6-EGFP-positive cells isolated by flow cytometry could differentiate into myosin 7a-positive hair cells after 10 days in-culture, and this suggests that the Lgr6-positive cells might serve as the hair cell progenitor cells in the cochlea. PMID:26029045

Effects of extremely low frequency electromagnetic fields on distortion product otoacoustic emissions in rabbits.

PubMed

Budak, Bilgehan; Budak, Gürer G; Oztürk, Göknur Güler; Muluk, Nuray Bayar; Apan, Alpaslan; Seyhan, Nesrin

2009-06-01

Humans are continuously exposed to extremely low frequency (ELF), electromagnetic fields (EMF), transmitted from the common sources like power stations, electric transmission lines, communication and radio-television signal transmission units. The present study aimed to assess the effects of 50 Hz ELF-EMF of 5.068 and 10.182 kV/m electric fields, which refer to the lower and upper intensity limits beyond which hazardous effects can be observed, on the auditory functions of rabbits via Distortion Product Otoacoustic Emission (DPOAE) recordings. The study was performed on 20 healthy adult female New Zealand White rabbits randomly divided into two groups and applied 50 Hz ELF-EMF with either 5.068 kV/m (Group 1) or 10.182 kV/m (Group 2) of electric field for 3h/day during 14 days. DPOAE responses recorded on the 0th day before exposure (B-EMF) and on the 6th (A-EMF-6th) and 14th (A-EMF-14th) days after exposure (AE). Mean stimulus intensity and emission amplitudes at 1.0-8.0 kHz were analyzed. In Group 2 rabbits, on 6th and 14th days, the DPOAE amplitudes were observed as increased at 1.5-4.0 kHz (at 2.0 and 4.0 kHz significantly) than B-EMF values. At 6.0 kHz, A-EMF-14th amplitudes were significantly lower than A-EMF values. These results suggest that ELF EMFs might affect hearing functions by frequency dependent manner. Higher ELF EMFs exposure caused increase of cochlear activity. Ototoxic effect of 10.182 kV/m ELF EMFs may begin at the basal turn of the cochlea by reducing DPOAEs at high frequencies.

Perilymph pharmacokinetics of markers and dexamethasone applied and sampled at the lateral semi-circular canal.

PubMed

Salt, Alec N; Hartsock, Jared J; Gill, Ruth M; Piu, Fabrice; Plontke, Stefan K

2012-12-01

Perilymph pharmacokinetics was investigated by a novel approach, in which solutions containing drug or marker were injected from a pipette sealed into the perilymphatic space of the lateral semi-circular canal (LSCC). The cochlear aqueduct provides the outlet for fluid flow so this procedure allows almost the entire perilymph to be exchanged. After wait times of up to 4 h the injection pipette was removed and multiple, sequential samples of perilymph were collected from the LSCC. Fluid efflux at this site results from cerebrospinal fluid (CSF) entry into the basal turn of scala tympani (ST) so the samples allow drug levels from different locations in the ear to be defined. This method allows the rate of elimination of substances from the inner ear to be determined more reliably than with other delivery methods in which drug may only be applied to part of the ear. Results were compared for the markers trimethylphenylammonium (TMPA) and fluorescein and for the drug dexamethasone (Dex). For each substance, the concentration in fluid samples showed a progressive decrease as the delay time between injection and sampling was increased. This is consistent with the elimination of substance from the ear with time. The decline with time was slowest for fluorescein, was fastest for Dex, with TMPA at an intermediate rate. Simulations of the experiments showed that elimination occurred more rapidly from scala tympani (ST) than from scala vestibuli (SV). Calculated elimination half-times from ST averaged 54.1, 24.5 and 22.5 min for fluorescein, TMPA and Dex respectively and from SV 1730, 229 and 111 min respectively. The elimination of Dex from ST occurred considerably faster than previously appreciated. These pharmacokinetic parameters provide an important foundation for understanding of drug treatments of the inner ear.

Effect of cochlear nerve electrocautery on the adult cochlear nucleus.

PubMed

Iseli, Claire E; Merwin, William H; Klatt-Cromwell, Cristine; Hutson, Kendall A; Ewend, Matthew G; Adunka, Oliver F; Fitzpatrick, Douglas C; Buchman, Craig A

2015-04-01

Electrocauterization and subsequent transection of the cochlear nerve induce greater injury to the cochlear nucleus than sharp transection alone. Some studies show that neurofibromatosis Type 2 (NF2) patients fit with auditory brainstem implants (ABIs) fail to achieve speech perception abilities similar to ABI recipients without NF2. Reasons for these differences remain speculative. One hypothesis posits poorer performance to surgically induced trauma to the cochlear nucleus from electrocautery. Sustained electrosurgical depolarization of the cochlear nerve may cause excitotoxic-induced postsynaptic nuclear injury. Equally plausible is that cautery in the vicinity of the cochlear nucleus induces necrosis. The cochlear nerve was transected in anesthetized adult gerbils sharply with or without bipolar electrocautery at varying intensities. Gerbils were perfused at 1, 3, 5, and 7 days postoperatively; their brainstem and cochleas were embedded in paraffin and sectioned at 10 μm. Alternate sections were stained with flourescent markers for neuronal injury or Nissl substance. In additional experiments, anterograde tracers were applied directly to a sectioned eighth nerve to verify that fluorescent-labeled profiles seen were terminating auditory nerve fibers. Cochlear nerve injury was observed from 72 hours postoperatively and was identical across cases regardless of surgical technique. Postsynaptic cochlear nucleus injury was not seen after distal transection of the nerve. By contrast, proximal transection was associated with trauma to the cochlear nucleus. Distal application of bipolar electrocautery seems safe for the cochlear nucleus. Application near the root entry zone must be used cautiously because this may compromise nuclear viability needed to support ABI stimulation.

Music Perception of Cochlear Implant Recipients with Implications for Music Instruction: A Review of Literature

PubMed Central

Hsiao, Feilin; Gfeller, Kate

2013-01-01

This review of literature presents a systematic analysis of the capabilities and limitations of cochlear implant recipients regarding music perception. Specifically, it a) analyzes individual components of music (e.g., rhythm, timbre, and pitch) as they interface with the technical characteristics of cochlear implants and the perceptual abilities of cochlear implant recipients; and b) describes accommodations for music instruction that support successful participation of children with cochlear implants. This article consolidates research studies from various disciplines (audiology, hearing science, speech-language pathology, cochlear implants, and music therapy) to provide practical recommendations for educators in fostering the musical growth of children with cochlear implants. PMID:23469365

Outcomes of cochlear implantation in deaf children of deaf parents: comparative study.

PubMed

Hassanzadeh, S

2012-10-01

This retrospective study compared the cochlear implantation outcomes of first- and second-generation deaf children. The study group consisted of seven deaf, cochlear-implanted children with deaf parents. An equal number of deaf children with normal-hearing parents were selected by matched sampling as a reference group. Participants were matched based on onset and severity of deafness, duration of deafness, age at cochlear implantation, duration of cochlear implantation, gender, and cochlear implant model. We used the Persian Auditory Perception Test for the Hearing Impaired, the Speech Intelligibility Rating scale, and the Sentence Imitation Test, in order to measure participants' speech perception, speech production and language development, respectively. Both groups of children showed auditory and speech development. However, the second-generation deaf children (i.e. deaf children of deaf parents) exceeded the cochlear implantation performance of the deaf children with hearing parents. This study confirms that second-generation deaf children exceed deaf children of hearing parents in terms of cochlear implantation performance. Encouraging deaf children to communicate in sign language from a very early age, before cochlear implantation, appears to improve their ability to learn spoken language after cochlear implantation.

Cochlear implant revision surgeries in children.

PubMed

Amaral, Maria Stella Arantes do; Reis, Ana Cláudia Mirândola B; Massuda, Eduardo T; Hyppolito, Miguel Angelo

2018-02-16

The surgery during which the cochlear implant internal device is implanted is not entirely free of risks and may produce problems that will require revision surgeries. To verify the indications for cochlear implantation revision surgery for the cochlear implant internal device, its effectiveness and its correlation with certain variables related to language and hearing. A retrospective study of patients under 18 years submitted to cochlear implant Surgery from 2004 to 2015 in a public hospital in Brazil. Data collected were: age at the time of implantation, gender, etiology of the hearing loss, audiological and oral language characteristics of each patient before and after Cochlear Implant surgery and any need for surgical revision and the reason for it. Two hundred and sixty-five surgeries were performed in 236 patients. Eight patients received a bilateral cochlear implant and 10 patients required revision surgery. Thirty-two surgeries were necessary for these 10 children (1 bilateral cochlear implant), of which 21 were revision surgeries. In 2 children, cochlear implant removal was necessary, without reimplantation, one with cochlear malformation due to incomplete partition type I and another due to trauma. With respect to the cause for revision surgery, of the 8 children who were successfully reimplanted, four had cochlear calcification following meningitis, one followed trauma, one exhibited a facial nerve malformation, one experienced a failure of the cochlear implant internal device and one revision surgery was necessary because the electrode was twisted. The incidence of the cochlear implant revision surgery was 4.23%. The period following the revision surgeries revealed an improvement in the subject's hearing and language performance, indicating that these surgeries are valid in most cases. Copyright © 2018 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Structural centrosome aberrations sensitize polarized epithelia to basal cell extrusion.

PubMed

Ganier, Olivier; Schnerch, Dominik; Nigg, Erich A

2018-06-01

Centrosome aberrations disrupt tissue architecture and may confer invasive properties to cancer cells. Here we show that structural centrosome aberrations, induced by overexpression of either Ninein-like protein (NLP) or CEP131/AZI1, sensitize polarized mammalian epithelia to basal cell extrusion. While unperturbed epithelia typically dispose of damaged cells through apical dissemination into luminal cavities, certain oncogenic mutations cause a switch in directionality towards basal cell extrusion, raising the potential for metastatic cell dissemination. Here we report that NLP-induced centrosome aberrations trigger the preferential extrusion of damaged cells towards the basal surface of epithelial monolayers. This switch in directionality from apical to basal dissemination coincides with a profound reorganization of the microtubule cytoskeleton, which in turn prevents the contractile ring repositioning that is required to support extrusion towards the apical surface. While the basal extrusion of cells harbouring NLP-induced centrosome aberrations requires exogenously induced cell damage, structural centrosome aberrations induced by excess CEP131 trigger the spontaneous dissemination of dying cells towards the basal surface from MDCK cysts. Thus, similar to oncogenic mutations, structural centrosome aberrations can favour basal extrusion of damaged cells from polarized epithelia. Assuming that additional mutations may promote cell survival, this process could sensitize epithelia to disseminate potentially metastatic cells. © 2018 The Authors.

Parental expectations and outcomes of pediatric cochlear implantation.

PubMed

Piazza, Elizabeth; Kandathil, Cherian; Carron, Jeffrey D

2009-10-01

Cochlear implants have been used with increasing frequency over the past twenty years, including very young patients. To determine if parents are satisfied with their children's performance after cochlear implantation. Survey mailed to parents of children receiving cochlear implants. 31 questionnaires were returned out of 69 mailed (45 %). The vast majority of responding parents felt that their children benefited substantially from cochlear implant surgery. Cochlear implantation is effective in helping children develop auditory-oral communication skills. Access to auditory/oral communication programs in this state remains an obstacle in postoperative habilitation.

Evolutionary origins of ultrasonic hearing and laryngeal echolocation in bats inferred from morphological analyses of the inner ear

PubMed Central

2013-01-01

Introduction Many mammals have evolved highly adapted hearing associated with ecological specialisation. Of these, bats possess the widest frequency range of vocalisations and associated hearing sensitivities, with frequencies of above 200 kHz in some lineages that use laryngeal echolocation. High frequency hearing in bats appears to have evolved via structural modifications of the inner ear, however, studying these minute features presents considerable challenges and hitherto few such attempts have been made. To understand these adaptations more fully, as well as gain insights into the evolutionary origins of ultrasonic hearing and echolocation in bats, we undertook micro-computed tomography (μCT) scans of the cochleae of representative bat species from 16 families, encompassing their broad range of ecological diversity. To characterise cochlear gross morphology, we measured the relative basilar membrane length and number of turns, and compared these values between echolocating and non-echolocating bats, as well as other mammals. Results We found that hearing and echolocation call frequencies in bats correlated with both measures of cochlear morphology. In particular, relative basilar membrane length was typically longer in echolocating species, and also correlated positively with the number of cochlear turns. Ancestral reconstructions of these parameters suggested that the common ancestor of all extant bats was probably capable of ultrasonic hearing; however, we also found evidence of a significant decrease in the rate of morphological evolution of the basilar membrane in multiple ancestral branches within the Yangochiroptera suborder. Within the echolocating Yinpterochiroptera, there was some evidence of an increase in the rate of basilar membrane evolution in some tips of the tree, possibly associated with reported shifts in call frequency associated with recent speciation events. Conclusions The two main groups of echolocating bat were found to display highly variable inner ear morphologies. Ancestral reconstructions and rate shift analyses of ear morphology point to a complex evolutionary history, with the former supporting ultrasonic hearing in the common bat ancestor but the latter suggesting that morphological changes associated with echolocation might have occurred later. These findings are consistent with theories that sophisticated laryngeal echolocation, as seen in modern lineages, evolved following the divergence of the two main suborders. PMID:23360746

Drug delivery into the cochlear apex: Improved control to sequentially affect finely spaced regions along the entire length of the cochlear spiral.

PubMed

Lichtenhan, J T; Hartsock, J; Dornhoffer, J R; Donovan, K M; Salt, A N

2016-11-01

Administering pharmaceuticals to the scala tympani of the inner ear is a common approach to study cochlear physiology and mechanics. We present here a novel method for in vivo drug delivery in a controlled manner to sealed ears. Injections of ototoxic solutions were applied from a pipette sealed into a fenestra in the cochlear apex, progressively driving solutions along the length of scala tympani toward the cochlear aqueduct at the base. Drugs can be delivered rapidly or slowly. In this report we focus on slow delivery in which the injection rate is automatically adjusted to account for varying cross sectional area of the scala tympani, therefore driving a solution front at uniform rate. Objective measurements originating from finely spaced, low- to high-characteristic cochlear frequency places were sequentially affected. Comparison with existing methods(s): Controlled administration of pharmaceuticals into the cochlear apex overcomes a number of serious limitations of previously established methods such as cochlear perfusions with an injection pipette in the cochlear base: The drug concentration achieved is more precisely controlled, drug concentrations remain in scala tympani and are not rapidly washed out by cerebrospinal fluid flow, and the entire length of the cochlear spiral can be treated quickly or slowly with time. Controlled administration of solutions into the cochlear apex can be a powerful approach to sequentially effect objective measurements originating from finely spaced cochlear regions and allows, for the first time, the spatial origin of CAPs to be objectively defined. Copyright © 2016 Elsevier B.V. All rights reserved.

Drug delivery into the cochlear apex: Improved control to sequentially affect finely spaced regions along the entire length of the cochlear spiral

PubMed Central

Lichtenhan, JT; Hartsock, J; Dornhoffer, JR; Donovan, KM; Salt, AN

2016-01-01

Background Administering pharmaceuticals to the scala tympani of the inner ear is a common approach to study cochlear physiology and mechanics. We present here a novel method for in vivo drug delivery in a controlled manner to sealed ears. New method Injections of ototoxic solutions were applied from a pipette sealed into a fenestra in the cochlear apex, progressively driving solutions along the length of scala tympani toward the cochlear aqueduct at the base. Drugs can be delivered rapidly or slowly. In this report we focus on slow delivery in which the injection rate is automatically adjusted to account for varying cross sectional area of the scala tympani, therefore driving a solution front at uniform rate. Results Objective measurements originating from finely spaced, low- to high-characteristic cochlear frequency places were sequentially affected. Comparison with existing methods(s): Controlled administration of pharmaceuticals into the cochlear apex overcomes a number of serious limitations of previously established methods such as cochlear perfusions with an injection pipette in the cochlear base: The drug concentration achieved is more precisely controlled, drug concentrations remain in scala tympani and are not rapidly washed out by cerebrospinal fluid flow, and the entire length of the cochlear spiral can be treated quickly or slowly with time. Conclusions Controlled administration of solutions into the cochlear apex can be a powerful approach to sequentially effect objective measurements originating from finely spaced cochlear regions and allows, for the first time, the spatial origin of CAPs to be objectively defined. PMID:27506463

Serotonin projection patterns to the cochlear nucleus.

PubMed

Thompson, A M; Thompson, G C

2001-07-13

The cochlear nucleus is well known as an obligatory relay center for primary auditory nerve fibers. Perhaps not so well known is the neural input to the cochlear nucleus from cells containing serotonin that reside near the midline in the midbrain raphe region. Although the specific locations of the main, if not sole, sources of serotonin within the dorsal cochlear nucleus subdivision are known to be the dorsal and median raphe nuclei, sources of serotonin located within other cochlear nucleus subdivisions are not currently known. Anterograde tract tracing was used to label fibers originating from the dorsal and median raphe nuclei while fluorescence immunohistochemistry was used to simultaneously label specific serotonin fibers in cat. Biotinylated dextran amine was injected into the dorsal and median raphe nuclei and was visualized with Texas Red, while serotonin was visualized with fluorescein. Thus, double-labeled fibers were unequivocally identified as serotoninergic and originating from one of the labeled neurons within the dorsal and median raphe nuclei. Double-labeled fiber segments, typically of fine caliber with oval varicosities, were observed in many areas of the cochlear nucleus. They were found in the molecular layer of the dorsal cochlear nucleus, in the small cell cap region, and in the granule cell and external regions of the cochlear nuclei, bilaterally, of all cats. However, the density of these double-labeled fiber segments varied considerably depending upon the exact region in which they were found. Fiber segments were most dense in the dorsal cochlear nucleus (especially in the molecular layer) and the large spherical cell area of the anteroventral cochlear nucleus; they were moderately dense in the small cell cap region; and fiber segments were least dense in the octopus and multipolar cell regions of the posteroventral cochlear nucleus. Because of the presence of labeled fiber segments in subdivisions of the cochlear nucleus other than the dorsal cochlear nucleus, we concluded that the serotoninergic projection pattern to the cochlear nucleus is divergent and non-specific. Double-labeled fiber segments were also present, but sparse, in the superior olive, localized mainly in periolivary regions; this indicated that the divergence of dorsal and median raphe neurons that extends throughout regions of the cochlear nucleus also extended well beyond the cochlear nucleus to include at least the superior olivary complex as well.

In vivo imaging and vibration measurement of Guinea pig cochlea

NASA Astrophysics Data System (ADS)

Choudhury, Niloy; Chen, Fangyi; Zheng, Jiefu; Nuttall, Alfred L.; Jacques, Steven L.

2008-02-01

An optical coherence tomography (OCT) system was built to acquire in vivo, both images and vibration measurements of the organ of Corti of the guinea pig. The organ of Corti was viewed through a ~500-μm diameter hole in the bony wall of the scala tympani of the first cochlear turn. In imaging mode, the image was acquired as reflectance R(x,z). In vibration mode, the basilar membrane (BM) or reticular lamina (RL) was selected based on the image. Under software control, the system would move the scanning mirrors to bring the sensing volume of the measurement to the desired tissue location. To address the gain stability problem of the homodyne OCT system, arising from the system moving in and out of the quadrature point and also to resolve the 180 degree ambiguity in the phase measurement using an interferometer, a vibration calibration method is developed by adding a vibrating source to the reference arm to monitor the operating point of the interferometric system. Amplitude gain and phase of various cochlear membranes was measured for different sound pressure level (SPL) varying from 65dB SPL to 93 dB SPL.

Cochlear implantation in patients with bilateral cochlear trauma.

PubMed

Serin, Gediz Murat; Derinsu, Ufuk; Sari, Murat; Gergin, Ozgül; Ciprut, Ayça; Akdaş, Ferda; Batman, Cağlar

2010-01-01

Temporal bone fracture, which involves the otic capsule, can lead to complete loss of auditory and vestibular functions, whereas the patients without fractures may experience profound sensorineural hearing loss due to cochlear concussion. Cochlear implant is indicated in profound sensorineural hearing loss due to cochlear trauma but who still have an intact auditory nerve. This is a retrospective review study. We report 5 cases of postlingually deafened patients caused by cochlear trauma, who underwent cochlear implantation. Preoperative and postoperative hearing performance will be presented. These patients are cochlear implanted after the cochlear trauma in our department between 2001 and 2006. All patients performed very well with their implants, obtained open-set speech understanding. They all became good telephone users after implantation. Their performance in speech understanding was comparable to standard postlingual adult patients implanted. Cochlear implantation is an effective aural rehabilitation in profound sensorineural hearing loss caused by temporal bone trauma. Preoperative temporal bone computed tomography, magnetic resonance imaging, and promontorium stimulation testing are necessary to make decision for the surgery and to determine the side to be implanted. Surgery could be challenging and complicated because of anatomical irregularity. Moreover, fibrosis and partial or total ossification within the cochlea must be expected. Copyright 2010. Published by Elsevier Inc.

Analysis of the cochlear amplifier fluid pump hypothesis.

PubMed

Zagadou, Brissi Franck; Mountain, David C

2012-04-01

We use analysis of a realistic three-dimensional finite-element model of the tunnel of Corti (ToC) in the middle turn of the gerbil cochlea tuned to the characteristic frequency (CF) of 4 kHz to show that the anatomical structure of the organ of Corti (OC) is consistent with the hypothesis that the cochlear amplifier functions as a fluid pump. The experimental evidence for the fluid pump is that outer hair cell (OHC) contraction and expansion induce oscillatory flow in the ToC. We show that this oscillatory flow can produce a fluid wave traveling in the ToC and that the outer pillar cells (OPC) do not present a significant barrier to fluid flow into the ToC. The wavelength of the resulting fluid wave launched into the tunnel at the CF is 1.5 mm, which is somewhat longer than the wavelength estimated for the classical traveling wave. This fluid wave propagates at least one wavelength before being significantly attenuated. We also investigated the effect of OPC spacing on fluid flow into the ToC and found that, for physiologically relevant spacing between the OPCs, the impedance estimate is similar to that of the underlying basilar membrane. We conclude that the row of OPCs does not significantly impede fluid exchange between ToC and the space between the row of OPC and the first row of OHC-Dieter's cells complex, and hence does not lead to excessive power loss. The BM displacement resulting from the fluid pumped into the ToC is significant for motion amplification. Our results support the hypothesis that there is an additional source of longitudinal coupling, provided by the ToC, as required in many non-classical models of the cochlear amplifier.

Bilateral Changes of Spontaneous Activity Within the Central Auditory Pathway Upon Chronic Unilateral Intracochlear Electrical Stimulation.

PubMed

Basta, Dietmar; Götze, Romy; Gröschel, Moritz; Jansen, Sebastian; Janke, Oliver; Tzschentke, Barbara; Boyle, Patrick; Ernst, Arne

2015-12-01

In recent years, cochlear implants have been applied successfully for the treatment of unilateral hearing loss with quite surprising benefit. One reason for this successful treatment, including the relief from tinnitus, could be the normalization of spontaneous activity in the central auditory pathway because of the electrical stimulation. The present study, therefore, investigated at a cellular level, the effect of a unilateral chronic intracochlear stimulation on key structures of the central auditory pathway. Normal-hearing guinea pigs were mechanically single-sided deafened through a standard HiFocus1j electrode array (on a HiRes 90k cochlear implant) being inserted into the first turn of the cochlea. Four to five electrode contacts could be used for the stimulation. Six weeks after surgery, the speech processor (Auria) was fitted, based on tNRI values and mounted on the animal's back. The two experimental groups were stimulated 16 hours per day for 90 days, using a HiRes strategy based on different stimulation rates (low rate (275 pps/ch), high rate (5000 pps/ch)). The results were compared with those of unilateral deafened controls (implanted but not stimulated), as well as between the treatment groups. All animals experienced a standardized free field auditory environment. The low-rate group showed a significantly lower average spontaneous activity bilaterally in the dorsal cochlear nucleus and the medial geniculate body than the controls. However, there was no difference in the inferior colliculus and the primary auditory cortex. Spontaneous activity of the high-rate group was also reduced bilaterally in the dorsal cochlear nucleus and in the primary auditory cortex. No differences could be observed between the high-rate group and the controls in the contra-lateral inferior colliculus and medial geniculate body. The high-rate group showed bilaterally a higher activity in the CN and the MGB compared with the low-rate group, whereas in the IC and in the AC a trend for an opposite effect could be determined. Unilateral intracochlear electrical stimulation seems to facilitate the homeostasis of the network activity, since it decreases the spontaneous activity that is usually elevated upon deafferentiation. The electrical stimulation per se seems to be responsible for the bilateral changes described above, rather than the particular nature of the electrical stimulation (e.g., rate). The normalization effects of electrical stimulation found in the present study are of particular importance in cochlear implant recipients with single-sided deafness.

Cochlear implant in Hong Kong Cantonese.

PubMed

Tang, S O; Luk, W S; Lau, C C; So, K W; Wong, C M; Yiu, M L; Kwok, C L

1990-11-01

Cochlear implant surgery was performed in four Cantonese-speaking postlingually deaf Chinese adults, using the House/3M single channel device. This article outlines the methodology, including preoperative assessment and postoperative rehabilitation; and explains the necessary modifications in speech and audiologic work-up in Cantonese-speaking patients. Salient features of Cantonese phonetics, especially its tonal characteristics, are described. The findings of the study are presented. The results of the cochlear implant would suggest a performance superior to that of the hearing aid. Furthermore, the cochlear implant is able to detect tonal cues. This quality of the cochlear implant may prove to be a valuable asset to a tonal language-speaking cochlear implantee.

Visualization and contractile activity of cochlear pericytes in the capillaries of the spiral ligament.

PubMed

Dai, Min; Nuttall, Alfred; Yang, Yue; Shi, Xiaorui

2009-08-01

Pericytes, mural cells located on microvessels, are considered to play an important role in the formation of the vasculature and the regulation of local blood flow in some organs. Little is known about the physiology of cochlear pericytes. In order to investigate the function of cochlear pericytes, we developed a method to visualize cochlear pericytes using diaminofluorescein-2 diacetate (DAF-2DA) and intravital fluorescence microscopy. This method can permit the study of the effect of vasoactive agents on pericytes under the in vivo and normal physiological condition. The specificity of the labeling method was verified by the immunofluorescence labeling of pericyte maker proteins such as desmin, neural proteoglycan (NG2), and thymocyte differentiation antigen 1 (Thy-1). Superfused K(+) and Ca(2+) to the cochlear lateral wall resulted in localized constriction of capillaries at pericyte locations both in vivo and in vitro, while there was no obvious change in cochlear capillary diameters with application of the adrenergic neurotransmitter noradrenaline. The method could be an effective way to visualize cochlear pericytes and microvessels and study lateral wall vascular physiology. Moreover, we demonstrate for the first time that cochlear pericytes have contractility, which may be important for regulation of cochlear blood flow.

Cochlear implants: system design, integration, and evaluation.

PubMed

Zeng, Fan-Gang; Rebscher, Stephen; Harrison, William; Sun, Xiaoan; Feng, Haihong

2008-01-01

As the most successful neural prosthesis, cochlear implants have provided partial hearing to more than 120000 persons worldwide; half of which being pediatric users who are able to develop nearly normal language. Biomedical engineers have played a central role in the design, integration and evaluation of the cochlear implant system, but the overall success is a result of collaborative work with physiologists, psychologists, physicians, educators, and entrepreneurs. This review presents broad yet in-depth academic and industrial perspectives on the underlying research and ongoing development of cochlear implants. The introduction accounts for major events and advances in cochlear implants, including dynamic interplays among engineers, scientists, physicians, and policy makers. The review takes a system approach to address critical issues in cochlear implant research and development. First, the cochlear implant system design and specifications are laid out. Second, the design goals, principles, and methods of the subsystem components are identified from the external speech processor and radio frequency transmission link to the internal receiver, stimulator and electrode arrays. Third, system integration and functional evaluation are presented with respect to safety, reliability, and challenges facing the present and future cochlear implant designers and users. Finally, issues beyond cochlear implants are discussed to address treatment options for the entire spectrum of hearing impairment as well as to use the cochlear implant as a model to design and evaluate other similar neural prostheses such as vestibular and retinal implants.

Sound-direction identification with bilateral cochlear implants.

PubMed

Neuman, Arlene C; Haravon, Anita; Sislian, Nicole; Waltzman, Susan B

2007-02-01

The purpose of this study was to compare the accuracy of sound-direction identification in the horizontal plane by bilateral cochlear implant users when localization was measured with pink noise and with speech stimuli. Eight adults who were bilateral users of Nucleus 24 Contour devices participated in the study. All had received implants in both ears in a single surgery. Sound-direction identification was measured in a large classroom by using a nine-loudspeaker array. Localization was tested in three listening conditions (bilateral cochlear implants, left cochlear implant, and right cochlear implant), using two different stimuli (a speech stimulus and pink noise bursts) in a repeated-measures design. Sound-direction identification accuracy was significantly better when using two implants than when using a single implant. The mean root-mean-square error was 29 degrees for the bilateral condition, 54 degrees for the left cochlear implant, and 46.5 degrees for the right cochlear implant condition. Unilateral accuracy was similar for right cochlear implant and left cochlear implant performance. Sound-direction identification performance was similar for speech and pink noise stimuli. The data obtained in this study add to the growing body of evidence that sound-direction identification with bilateral cochlear implants is better than with a single implant. The similarity in localization performance obtained with the speech and pink noise supports the use of either stimulus for measuring sound-direction identification.

Cochlear Implants Special Issue Article: Vocal Emotion Recognition by Normal-Hearing Listeners and Cochlear Implant Users

PubMed Central

Luo, Xin; Fu, Qian-Jie; Galvin, John J.

2007-01-01

The present study investigated the ability of normal-hearing listeners and cochlear implant users to recognize vocal emotions. Sentences were produced by 1 male and 1 female talker according to 5 target emotions: angry, anxious, happy, sad, and neutral. Overall amplitude differences between the stimuli were either preserved or normalized. In experiment 1, vocal emotion recognition was measured in normal-hearing and cochlear implant listeners; cochlear implant subjects were tested using their clinically assigned processors. When overall amplitude cues were preserved, normal-hearing listeners achieved near-perfect performance, whereas listeners with cochlear implant recognized less than half of the target emotions. Removing the overall amplitude cues significantly worsened mean normal-hearing and cochlear implant performance. In experiment 2, vocal emotion recognition was measured in listeners with cochlear implant as a function of the number of channels (from 1 to 8) and envelope filter cutoff frequency (50 vs 400 Hz) in experimental speech processors. In experiment 3, vocal emotion recognition was measured in normal-hearing listeners as a function of the number of channels (from 1 to 16) and envelope filter cutoff frequency (50 vs 500 Hz) in acoustic cochlear implant simulations. Results from experiments 2 and 3 showed that both cochlear implant and normal-hearing performance significantly improved as the number of channels or the envelope filter cutoff frequency was increased. The results suggest that spectral, temporal, and overall amplitude cues each contribute to vocal emotion recognition. The poorer cochlear implant performance is most likely attributable to the lack of salient pitch cues and the limited functional spectral resolution. PMID:18003871

Visualization of spiral ganglion neurites within the scala tympani with a cochlear implant in situ

PubMed Central

Chikar, Jennifer A.; Batts, Shelley A.; Pfingst, Bryan E.; Raphael, Yehoash

2009-01-01

Current cochlear histology methods do not allow in situ processing of cochlear implants. The metal components of the implant preclude standard embedding and mid-modiolar sectioning, and whole mounts do not have the spatial resolution needed to view the implant within the scala tympani. One focus of recent auditory research is the regeneration of structures within the cochlea, particularly the ganglion cells and their processes, and there are multiple potential benefits to cochlear implant users from this work. To facilitate experimental investigations of auditory nerve regeneration performed in conjunction with cochlear implantation, it is critical to visualize the cochlear tissue and the implant together to determine if the nerve has made contact with the implant. This paper presents a novel histological technique that enables simultaneous visualization of the in situ cochlear implant and neurofilament – labeled nerve processes within the scala tympani, and the spatial relationship between them. PMID:19428528

Visualization of spiral ganglion neurites within the scala tympani with a cochlear implant in situ.

PubMed

Chikar, Jennifer A; Batts, Shelley A; Pfingst, Bryan E; Raphael, Yehoash

2009-05-15

Current cochlear histology methods do not allow in situ processing of cochlear implants. The metal components of the implant preclude standard embedding and mid-modiolar sectioning, and whole mounts do not have the spatial resolution needed to view the implant within the scala tympani. One focus of recent auditory research is the regeneration of structures within the cochlea, particularly the ganglion cells and their processes, and there are multiple potential benefits to cochlear implant users from this work. To facilitate experimental investigations of auditory nerve regeneration performed in conjunction with cochlear implantation, it is critical to visualize the cochlear tissue and the implant together to determine if the nerve has made contact with the implant. This paper presents a novel histological technique that enables simultaneous visualization of the in situ cochlear implant and neurofilament-labeled nerve processes within the scala tympani, and the spatial relationship between them.

[Emotional response to music by postlingually-deafened adult cochlear implant users].

PubMed

Wang, Shuo; Dong, Ruijuan; Zhou, Yun; Li, Jing; Qi, Beier; Liu, Bo

2012-10-01

To assess the emotional response to music by postlingually-deafened adult cochlear implant users. Munich music questionnaire (MUMU) was used to match the music experience and the motivation of use of music between 12 normal-hearing and 12 cochlear implant subjects. Emotion rating test in Musical Sounds in Cochlear Implants (MuSIC) test battery was used to assess the emotion perception ability for both normal-hearing and cochlear implant subjects. A total of 15 pieces of music phases were used. Responses were given by selecting the rating scales from 1 to 10. "1" represents "very sad" feeling, and "10" represents "very happy feeling. In comparison with normal-hearing subjects, 12 cochlear implant subjects made less active use of music for emotional purpose. The emotion ratings for cochlear implant subjects were similar to normal-hearing subjects, but with large variability. Post-lingually deafened cochlear implant subjects on average performed similarly in emotion rating tasks relative to normal-hearing subjects, but their active use of music for emotional purpose was obviously less than normal-hearing subjects.

Guideline on cochlear implants.

PubMed

Manrique, Manuel; Ramos, Ángel; de Paula Vernetta, Carlos; Gil-Carcedo, Elisa; Lassaleta, Luis; Sanchez-Cuadrado, Isabel; Espinosa, Juan Manuel; Batuecas, Ángel; Cenjor, Carlos; Lavilla, María José; Núñez, Faustino; Cavalle, Laura; Huarte, Alicia

2018-03-26

In the last decade numerous hospitals have started to work with patients who are candidates for a cochlear implant (CI) and there have been numerous and relevant advances in the treatment of sensorineural hearing loss that extended the indications for cochlear implants. To provide a guideline on cochlear implants to specialists in otorhinolaryngology, other medical specialities, health authorities and society in general. The Scientific Committees of Otology, Otoneurology and Audiology from the Spanish Society of Otolaryngology and Head and Neck Surgery (SEORL-CCC), in a coordinated and agreed way, performed a review of the current state of CI based on the existing regulations and in the scientific publications referenced in the bibliography of the document drafted. The clinical guideline on cochlear implants provides information on: a) Definition and description of Cochlear Implant; b) Indications for cochlear implants; c) Organizational requirements for a cochlear implant programme. A clinical guideline on cochlear implants has been developed by a Committee of Experts of the SEORL-CCC, to help and guide all the health professionals involved in this field of CI in decision-making to treathearing impairment. Copyright © 2018 Sociedad Española de Otorrinolaringología y Cirugía de Cabeza y Cuello. Publicado por Elsevier España, S.L.U. All rights reserved.

The intralaminar thalamus—an expressway linking visual stimuli to circuits determining agency and action selection

PubMed Central

Fisher, Simon D.; Reynolds, John N. J.

2014-01-01

Anatomical investigations have revealed connections between the intralaminar thalamic nuclei and areas such as the superior colliculus (SC) that receive short latency input from visual and auditory primary sensory areas. The intralaminar nuclei in turn project to the major input nucleus of the basal ganglia, the striatum, providing this nucleus with a source of subcortical excitatory input. Together with a converging input from the cerebral cortex, and a neuromodulatory dopaminergic input from the midbrain, the components previously found necessary for reinforcement learning in the basal ganglia are present. With this intralaminar sensory input, the basal ganglia are thought to play a primary role in determining what aspect of an organism’s own behavior has caused salient environmental changes. Additionally, subcortical loops through thalamic and basal ganglia nuclei are proposed to play a critical role in action selection. In this mini review we will consider the anatomical and physiological evidence underlying the existence of these circuits. We will propose how the circuits interact to modulate basal ganglia output and solve common behavioral learning problems of agency determination and action selection. PMID:24765070

Cochlear implants in children implanted in Jordan: A parental overview.

PubMed

Alkhamra, Rana A

2015-07-01

Exploring the perspective of parents on the cochlear implant process in Jordan. Sixty parents of deaf children were surveyed on the information gathering process prior to cochlear implant surgery, and their implant outcome expectations post-surgery. Whether child or parent characteristics may impact parents' post-surgical expectations was explored. Although parents used a variety of information sources when considering a cochlear implant, the ear, nose and throat doctor comprised their major source of information (60%). Parents received a range of information prior to cochlear implant but agreed (93.3%) on the need for a multidisciplinary team approach. Post-surgically, parents' expected major developments in the areas of spoken language (97%), and auditory skills (100%). Receiving education in mainstream schools (92%) was expected too. Parents perceived the cochlear implant decision as the best decision they can make for their child (98.3%). A significant correlation was found between parents contentment with the cochlear implant decision and expecting developments in the area of reading and writing (r=0.7). Child's age at implantation and age at hearing loss diagnosis significantly affected parents' post-implant outcome expectations (p<0.05). Despite the general satisfaction from the information quantity and quality prior to cochlear implant, parents agree on the need for a comprehensive multidisciplinary team approach during the different stages of the cochlear implant process. Parents' education about cochlear implants prior to the surgery can affect their post-surgical outcome expectations. The parental perspective presented in this study can help professionals develop better understanding of parents' needs and expectations and henceforth improve their services and support during the different stages of the cochlear implant process. Copyright © 2015. Published by Elsevier Ireland Ltd.

Bilateral cochlear implantation in a patient with bilateral temporal bone fractures.

PubMed

Chung, Jae Ho; Shin, Myung Chul; Min, Hyun Jung; Park, Chul Won; Lee, Seung Hwan

2011-01-01

With the emphasis on bilateral hearing nowadays, bilateral cochlear implantation has been tried out for bilateral aural rehabilitation. Bilateral sensorineural hearing loss caused by head trauma can get help from cochlear implantation. We present the case of a 44-year-old man with bilateral otic capsule violating temporal bone fractures due to head trauma. The patient demonstrated much improved audiometric and psychoacoustic performance after bilateral cochlear implantation. We believe bilateral cochlear implantation in such patient can be a very effective tool for rehabilitation. Copyright © 2011 Elsevier Inc. All rights reserved.

Processing of speech temporal and spectral information by users of auditory brainstem implants and cochlear implants.

PubMed

Azadpour, Mahan; McKay, Colette M

2014-01-01

Auditory brainstem implants (ABI) use the same processing strategy as was developed for cochlear implants (CI). However, the cochlear nucleus (CN), the stimulation site of ABIs, is anatomically and physiologically more complex than the auditory nerve and consists of neurons with differing roles in auditory processing. The aim of this study was to evaluate the hypotheses that ABI users are less able than CI users to access speech spectro-temporal information delivered by the existing strategies and that the sites stimulated by different locations of CI and ABI electrode arrays differ in encoding of temporal patterns in the stimulation. Six CI users and four ABI users of Nucleus implants with ACE processing strategy participated in this study. Closed-set perception of aCa syllables (16 consonants) and bVd words (11 vowels) was evaluated via experimental processing strategies that activated one, two, or four of the electrodes of the array in a CIS manner as well as subjects' clinical strategies. Three single-channel strategies presented the overall temporal envelope variations of the signal on a single-implant electrode located at the high-, medium-, and low-frequency regions of the array. Implantees' ability to discriminate within electrode temporal patterns of stimulation for phoneme perception and their ability to make use of spectral information presented by increased number of active electrodes were assessed in the single- and multiple-channel strategies, respectively. Overall percentages and information transmission of phonetic features were obtained for each experimental program. Phoneme perception performance of three ABI users was within the range of CI users in most of the experimental strategies and improved as the number of active electrodes increased. One ABI user performed close to chance with all the single and multiple electrode strategies. There was no significant difference between apical, basal, and middle CI electrodes in transmitting speech temporal information, except a trend that the voicing feature was the least transmitted by the basal electrode. A similar electrode-location pattern could be observed in most ABI subjects. Although the number of tested ABI subjects was small, their wide range of phoneme perception performance was consistent with previous reports of overall speech perception in ABI patients. The better-performing ABI user participants had access to speech temporal and spectral information that was comparable to that of average CI user. The poor-performing ABI user did not have access to within-channel speech temporal information and did not benefit from an increased number of spectral channels. The within-subject variability between different ABI electrodes was less than the variability across users in transmission of speech temporal information. The difference in the performance of ABI users could be related to the location of their electrode array on the CN, anatomy, and physiology of their CN or the damage to their auditory brainstem due to tumor or surgery.

Close-field electroporation gene delivery using the cochlear implant electrode array enhances the bionic ear.

PubMed

Pinyon, Jeremy L; Tadros, Sherif F; Froud, Kristina E; Y Wong, Ann C; Tompson, Isabella T; Crawford, Edward N; Ko, Myungseo; Morris, Renée; Klugmann, Matthias; Housley, Gary D

2014-04-23

The cochlear implant is the most successful bionic prosthesis and has transformed the lives of people with profound hearing loss. However, the performance of the "bionic ear" is still largely constrained by the neural interface itself. Current spread inherent to broad monopolar stimulation of the spiral ganglion neuron somata obviates the intrinsic tonotopic mapping of the cochlear nerve. We show in the guinea pig that neurotrophin gene therapy integrated into the cochlear implant improves its performance by stimulating spiral ganglion neurite regeneration. We used the cochlear implant electrode array for novel "close-field" electroporation to transduce mesenchymal cells lining the cochlear perilymphatic canals with a naked complementary DNA gene construct driving expression of brain-derived neurotrophic factor (BDNF) and a green fluorescent protein (GFP) reporter. The focusing of electric fields by particular cochlear implant electrode configurations led to surprisingly efficient gene delivery to adjacent mesenchymal cells. The resulting BDNF expression stimulated regeneration of spiral ganglion neurites, which had atrophied 2 weeks after ototoxic treatment, in a bilateral sensorineural deafness model. In this model, delivery of a control GFP-only vector failed to restore neuron structure, with atrophied neurons indistinguishable from unimplanted cochleae. With BDNF therapy, the regenerated spiral ganglion neurites extended close to the cochlear implant electrodes, with localized ectopic branching. This neural remodeling enabled bipolar stimulation via the cochlear implant array, with low stimulus thresholds and expanded dynamic range of the cochlear nerve, determined via electrically evoked auditory brainstem responses. This development may broadly improve neural interfaces and extend molecular medicine applications.

Predicting social functioning in children with a cochlear implant and in normal-hearing children: the role of emotion regulation.

PubMed

Wiefferink, Carin H; Rieffe, Carolien; Ketelaar, Lizet; Frijns, Johan H M

2012-06-01

The purpose of the present study was to compare children with a cochlear implant and normal hearing children on aspects of emotion regulation (emotion expression and coping strategies) and social functioning (social competence and externalizing behaviors) and the relation between emotion regulation and social functioning. Participants were 69 children with cochlear implants (CI children) and 67 normal hearing children (NH children) aged 1.5-5 years. Parents answered questionnaires about their children's language skills, social functioning, and emotion regulation. Children also completed simple tasks to measure their emotion regulation abilities. Cochlear implant children had fewer adequate emotion regulation strategies and were less socially competent than normal hearing children. The parents of cochlear implant children did not report fewer externalizing behaviors than those of normal hearing children. While social competence in normal hearing children was strongly related to emotion regulation, cochlear implant children regulated their emotions in ways that were unrelated with social competence. On the other hand, emotion regulation explained externalizing behaviors better in cochlear implant children than in normal hearing children. While better language skills were related to higher social competence in both groups, they were related to fewer externalizing behaviors only in cochlear implant children. Our results indicate that cochlear implant children have less adequate emotion-regulation strategies and less social competence than normal hearing children. Since they received their implants relatively recently, they might eventually catch up with their hearing peers. Longitudinal studies should further explore the development of emotion regulation and social functioning in cochlear implant children. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

[The development of musicality in children after cochlear implantation].

PubMed

Zheng, Yan; Liu, Bo; Dong, Ruijuan; Xu, Tianqiu; Chen, Jing; Chen, Xuejing; Zhong, Yan; Meng, Chao; Wang, Hong; Chen, Xueqing

2014-08-01

The purpose of this study is to analyze the development of musicality in children after cochlear implantation, and provide a clinical database for the evaluation of their musicality. Twenty-six children with cochlear implants (CI group) participated in this research. They received cochlear implants at the age of 11 to 68 months with a mean of 35.6 months. Seventy-six infants as a control group aged from 1 to 24 months with a mean of 6.1 months participated in this study, whose hearing were considered normal by passing the case history collection, high-risk registers for hearing loss and hearing screening using DPOAE. The music and young children with CIs: Musicality Rating Scale was used to evaluate their musicality. The evaluation was performed before cochlear implantation and 1, 3, 6, 9, 12, 24 months after cochlear implantation for children with cochlear implants. The evaluation was also performed at 1, 3, 6, 9, 12, 24 months for children with normal hearing. The mean scores of musicality showed significant improvements with time of CI use for CI group (P<0.05). The mean scores of musicality also showed significant improvements with time for control group (P<0.05). There were no significant differences in mean scores between CI group and control group at 1, 3, 6, 9, 12 months of hearing age by rank sum test (P>0.05). Significant difference was noted between the two groups at 24 months (P<0.05). The musicality of children with cochlear implants improved significantly with time after cochlear implantation. The most rapid growth was found in the first year after cochlear implantation.

Cochlear Implants:System Design, Integration and Evaluation

PubMed Central

Rebscher, Stephen; Harrison, William V.; Sun, Xiaoan; Feng, Haihong

2009-01-01

As the most successful neural prosthesis, cochlear implants have provided partial hearing to more than 120,000 persons worldwide; half of which being pediatric users who are able to develop nearly normal language. Biomedical engineers have played a central role in the design, integration and evaluation of the cochlear implant system, but the overall success is a result of collaborative work with physiologists, psychologists, physicians, educators, and entrepreneurs. This review presents broad yet in-depth academic and industrial perspectives on the underlying research and ongoing development of cochlear implants. The introduction accounts for major events and advances in cochlear implants, including dynamic interplays among engineers, scientists, physicians, and policy makers. The review takes a system approach to address critical issues from design and specifications to integration and evaluation. First, the cochlear implant system design and specifications are laid out. Second, the design goals, principles, and methods of the subsystem components are identified from the external speech processor and radio frequency transmission link to the internal receiver, stimulator and electrode arrays. Third, system integration and functional evaluation are presented with respect to safety, reliability, and challenges facing the present and future cochlear implant designers and users. Finally, issues beyond cochlear implants are discussed to address treatment options for the entire spectrum of hearing impairment as well as to use the cochlear implant as a model to design and evaluate other similar neural prostheses such as vestibular and retinal implants. PMID:19946565

Remote programming of cochlear implants: a telecommunications model.

PubMed

McElveen, John T; Blackburn, Erin L; Green, J Douglas; McLear, Patrick W; Thimsen, Donald J; Wilson, Blake S

2010-09-01

Evaluate the effectiveness of remote programming for cochlear implants. Retrospective review of the cochlear implant performance for patients who had undergone mapping and programming of their cochlear implant via remote connection through the Internet. Postoperative Hearing in Noise Test and Consonant/Nucleus/Consonant word scores for 7 patients who had undergone remote mapping and programming of their cochlear implant were compared with the mean scores of 7 patients who had been programmed by the same audiologist over a 12-month period. Times required for remote and direct programming were also compared. The quality of the Internet connection was assessed using standardized measures. Remote programming was performed via a virtual private network with a separate software program used for video and audio linkage. All 7 patients were programmed successfully via remote connectivity. No untoward patient experiences were encountered. No statistically significant differences could be found in comparing postoperative Hearing in Noise Test and Consonant/Nucleus/Consonant word scores for patients who had undergone remote programming versus a similar group of patients who had their cochlear implant programmed directly. Remote programming did not require a significantly longer programming time for the audiologist with these 7 patients. Remote programming of a cochlear implant can be performed safely without any deterioration in the quality of the programming. This ability to remotely program cochlear implant patients gives the potential to extend cochlear implantation to underserved areas in the United States and elsewhere.

Protective role of hydrogen sulfide against noise-induced cochlear damage: a chronic intracochlear infusion model.

PubMed

Li, Xu; Mao, Xiao-Bo; Hei, Ren-Yi; Zhang, Zhi-Bin; Wen, Li-Ting; Zhang, Peng-Zhi; Qiu, Jian-Hua; Qiao, Li

2011-01-01

A reduction in cochlear blood flow plays an essential role in noise-induced hearing loss (NIHL). The timely regulation of cochlear perfusion determines the progression and prognosis of NIHL. Hydrogen sulfide (H(2)S) has attracted increasing interest as a vasodilator in cardiovascular systems. This study identified the role of H(2)S in cochlear blood flow regulation and noise protection. The gene and protein expression of the H(2)S synthetase cystathionine-γ-lyase (CSE) in the rat cochlea was examined using immunofluorescence and real-time PCR. Cochlear CSE mRNA levels varied according to the duration of noise exposure. A chronic intracochlear infusion model was built and artificial perilymph (AP), NaHS or DL-propargylglycine (PPG) were locally administered. Local sodium hydrosulfide (NaHS) significantly increased cochlear perfusion post-noise exposure. Cochlear morphological damage and hearing loss were alleviated in the NaHS group as measured by conventional auditory brainstem response (ABR), cochlear scanning electron microscope (SEM) and outer hair cell (OHC) count. The highest percentage of OHC loss occurred in the PPG group. Our results suggest that H(2)S plays an important role in the regulation of cochlear blood flow and the protection against noise. Further studies may identify a new preventive and therapeutic perspective on NIHL and other blood supply-related inner ear diseases.

Cochlear Patency After Transmastoid Labyrinthectomy for Ménière's Syndrome.

PubMed

Sargent, Eric W; Liao, Eric; Gonda, Roger L

2016-08-01

Labyrinthectomy is considered the "gold standard" in the treatment of intractable vertigo attacks because of Ménière's Disease (MD) but sacrifices all residual hearing. Interest in auditory rehabilitation has lead to cochlear implantation in some patients. Concern remains that the cochlear lumen may fill with tissue or bone after surgery. This study sought to determine the incidence of obliteration of the cochlea after transmastoid labyrinthectomy. Retrospective observational study. Tertiary referral center. Eighteen patients with intractable vertigo from MD who underwent surgery. Transmastoid labyrinthectomy between 2008 and 2013. Cochleas were imaged with unenhanced, heavily T2-weighted magnetic resonance imaging (MRI). Presence of symmetrical cochlear fluid signals on MRI. There was no loss of fluid signal in the cochleas of operated ear compared with the contralateral, unoperated ear in any subject an average of 3 years (standard deviation [SD]: 1.2) after surgery. Five of 18 patients had the vestibule blocked with bone wax at the time of surgery. Blocking the vestibule with bone wax did not change the cochlear fluid signal. The risk of cochlear obstruction after labyrinthectomy for MD is very low. The significance of this finding is that patients with MD who undergo labyrinthectomy will likely remain candidates for cochlear implantation in the labyrinthectomized ear long after surgery if this becomes needed. Immediate cochlear implantation or placement of a cochlear lumen keeper during labyrinthectomy for MD is probably not necessary.

Music mixing preferences of cochlear implant recipients: a pilot study.

PubMed

Buyens, Wim; van Dijk, Bas; Moonen, Marc; Wouters, Jan

2014-05-01

Music perception and appraisal are generally poor in cochlear implant recipients. Simple musical structures, lyrics that are easy to follow, and clear rhythm/beat have been reported among the top factors to enhance music enjoyment. The present study investigated the preference for modified relative instrument levels in music with normal-hearing and cochlear implant subjects. In experiment 1, test subjects were given a mixing console and multi-track recordings to determine their most enjoyable audio mix. In experiment 2, a preference rating experiment based on the preferred relative level settings in experiment 1 was performed. Experiment 1 was performed with four postlingually deafened cochlear implant subjects, experiment 2 with ten normal-hearing and ten cochlear implant subjects. A significant difference in preference rating was found between normal-hearing and cochlear implant subjects. The latter preferred an audio mix with larger vocals-to-instruments ratio. In addition, given an audio mix with clear vocals and attenuated instruments, cochlear implant subjects preferred the bass/drum track to be louder than the other instrument tracks. The original audio mix in real-world music might not be suitable for cochlear implant recipients. Modifying the relative instrument level settings potentially improves music enjoyment.

Betahistine metabolites, aminoethylpyridine, and hydroxyethylpyridine increase cochlear blood flow in guinea pigs in vivo.

PubMed

Bertlich, Mattis; Ihler, Fritz; Sharaf, Kariem; Weiss, Bernhard G; Strupp, Michael; Canis, Martin

2014-10-01

Betahistine is a histamine-like drug that is used in the treatment of Ménière's disease. It is commonly believed that betahistine increases cochlear blood flow and thus decreases the endolymphatic hydrops that is the cause of Ménière's. Despite common clinical use, there is little understanding of the kinetics or effects of its metabolites. This study investigated the effect of the betahistine metabolites aminoethylpyridine, hydroxyethylpyridine, and pyridylacetic acid on cochlear microcirculation. Guinea pigs were randomly assigned to one of the groups: placebo, betahistine, or equimolar amounts of aminoethylpyridine, hydroxyethylpyridine, or pyridylacetic acid. Cochlear blood flow and mean arterial pressure were recorded for three minutes before and 15 minutes after treatment. Thirty Dunkin-Hartley guinea pigs assigned to one of five groups with six guinea pigs per group. Betahistine, aminoethylpyridine, and hydroxyethylpyridine caused a significant increase in cochlear blood flow in comparison to placebo. The effect seen under aminoethylpyridin was greatest. The group treated with pyridylacetic acid showed no significant effect on cochlear blood flow. Aminoethylpyridine and hydroxyethylpyridine are, like betahistine, able to increase cochlear blood flow significantly. The effect of aminoethylpyridine was greatest. Pyridylacetic acid had no effect on cochlear microcirculation.

Histaminergic H3-Heteroreceptors as a Potential Mediator of Betahistine-Induced Increase in Cochlear Blood Flow.

PubMed

Bertlich, Mattis; Ihler, Friedrich; Freytag, Saskia; Weiss, Bernhard G; Strupp, Michael; Canis, Martin

2015-01-01

Betahistine is a histamine-like drug that is considered beneficial in Ménière's disease by increasing cochlear blood flow. Acting as an agonist at the histamine H1-receptor and as an inverse agonist at the H3-receptor, these receptors as well as the adrenergic α2-receptor were investigated for betahistine effects on cochlear blood flow. A total of 54 Dunkin-Hartley guinea pigs were randomly assigned to one of nine groups treated with a selection of H1-, H3- or α2-selective agonists and antagonists together with betahistine. Cochlear blood flow and mean arterial pressure were recorded for 3 min before and 15 min after infusion. Blockage of the H3- or α2-receptors caused a suppression of betahistine-mediated typical changes in cochlear blood flow or blood pressure. Activation of H3-receptors caused a drop in cochlear blood flow and blood pressure. H1-receptors showed no involvement in betahistine-mediated changes of cochlear blood flow. Betahistine most likely affects cochlear blood flow through histaminergic H3-heteroreceptors. © 2015 S. Karger AG, Basel.

Fingolimod (FTY-720) is Capable of Reversing Tumor Necrosis Factor Induced Decreases in Cochlear Blood Flow.

PubMed

Bertlich, Mattis; Ihler, Friedrich; Weiss, Bernhard G; Freytag, Saskia; Jakob, Mark; Strupp, Michael; Pellkofer, Hannah; Canis, Martin

2017-09-01

The potential of Fingolimod (FTY-720), a sphingosine-1-phosphate analogue, to revoke the changes in cochlear blood flow induced by tumor necrosis factor (TNF) was investigated. Impairment of cochlear blood flow has often been considered as the common final pathway of various inner ear pathologies. TNF, an ubiquitous cytokine, plays a major role in these pathologies, reducing cochlear blood flow via sphingosine-1-phosphate-signaling. Fifteen Dunkin-Hartley guinea pigs were randomly assigned to one of three groups (placebo/placebo, TNF/placebo, TNF/FTY-720). Cochlear microcirculation was quantified over 60 minutes by in vivo fluorescence microscopy before and after topical application of placebo or TNF (5 ng/ml) and after subsequent application of placebo or FTY-720 (200 μg/ml). Treatment with TNF led to a significant decrease of cochlear blood flow.Following this, application of placebo caused no significant changes while application of FTY-720 caused a significant rise in cochlear blood flow. FTY-720 is capable of reversing changes in cochlear blood flow induced by application of TNF. This makes FTY-720 a valid candidate for potential treatment of numerous inner ear pathologies.

[Cochlear implantation in patients with Waardenburg syndrome type II].

PubMed

Wan, Liangcai; Guo, Menghe; Chen, Shuaijun; Liu, Shuangriu; Chen, Hao; Gong, Jian

2010-05-01

To describe the multi-channel cochlear implantation in patients with Waardenburg syndrome including surgeries, pre and postoperative hearing assessments as well as outcomes of speech recognition. Multi-channel cochlear implantation surgeries have been performed in 12 cases with Waardenburg syndrome type II in our department from 2000 to 2008. All the patients received multi-channel cochlear implantation through transmastoid facial recess approach. The postoperative outcomes of 12 cases were compared with 12 cases with no inner ear malformation as a control group. The electrodes were totally inserted into the cochlear successfully, there was no facial paralysis and cerebrospinal fluid leakage occurred after operation. The hearing threshold in this series were similar to that of the normal cochlear implantation. After more than half a year of speech rehabilitation, the abilities of speech discrimination and spoken language of all the patients were improved compared with that of preoperation. Multi-channel cochlear implantation could be performed in the cases with Waardenburg syndrome, preoperative hearing and images assessments should be done.

United Kingdom national paediatric bilateral cochlear implant audit: preliminary results.

PubMed

Cullington, Helen; Bele, Devyanee; Brinton, Julie; Lutman, Mark

2013-11-01

Prior to 2009, United Kingdom (UK) public funding was mainly only available for children to receive unilateral cochlear implants. In 2009, the National Institute for Health and Care Excellence published guidance for cochlear implantation following their review. According to these guidelines, all suitable children are eligible to have simultaneous bilateral cochlear implants or a sequential bilateral cochlear implant if they had received the first before the guidelines were published. Fifteen UK cochlear implant centres formed a consortium to carry out a multi-centre audit. The audit involves collecting data from simultaneously and sequentially implanted children at four intervals: before bilateral cochlear implants or before the sequential implant, 1, 2, and 3 years after bilateral implants. The measures include localization, speech recognition in quiet and background noise, speech production, listening, vocabulary, parental perception, quality of life, and surgical data including complications. The audit has now passed the 2-year point, and data have been received on 850 children. This article provides a first view of some data received up until March 2012.

Ischemia-reperfusion injury of the cochlea: pharmacological strategies for cochlear protection and implications of glutamate and reactive oxygen species.

PubMed

Tabuchi, Keiji; Nishimura, Bungo; Tanaka, Shuho; Hayashi, Kentaro; Hirose, Yuki; Hara, Akira

2010-06-01

A large amount of energy produced by active aerobic metabolism is necessary for the cochlea to maintain its function. This makes the cochlea vulnerable to blockade of cochlear blood flow and interruption of the oxygen supply. Although certain forms of human idiopathic sudden sensorineural hearing loss reportedly arise from ischemic injury, the pathological mechanism of cochlear ischemia-reperfusion injury has not been fully elucidated. Recent animal studies have shed light on the mechanisms of cochlear ischemia-reperfusion injury. It will help in the understanding of the pathology of cochlear ischemia-reperfusion injury to classify this injury into ischemic injury and reperfusion injury. Excitotoxicity, mainly observed during the ischemic period, aggravates the injury of primary auditory neurons. On the other hand, oxidative damage induced by hydroxyl radicals and nitric oxide enhances cochlear reperfusion injury. This article briefly summarizes the generation mechanisms of cochlear ischemia-reperfusion injury and potential therapeutic targets that could be developed for the effective management of this injury type.

Musical ear syndrome in adult cochlear implant patients.

PubMed

Low, W-K; Tham, C A; D'Souza, V-D; Teng, S-W

2013-09-01

Except for a single case report, musical ear syndrome in cochlear implantees has not been studied. We aimed to study the prevalence and nature of musical ear syndrome among adult cochlear implant patients, as well as the effect on their emotional well-being. STUDY DESIGN, PATIENTS AND INTERVENTION: A cross-sectional survey of patients aged 18 years and above who had received cochlear implants for profound hearing loss between 1997 and 2010. Of the 82 patients studied, 18 (22 per cent) were found to have experienced musical ear syndrome. Seven and 11 patients had musical ear syndrome prior to and after cochlear implantation, respectively. The character of musical ear syndrome symptoms was described as instrumental music (n = 2), singing (6) or both (10). Fourteen patients reported an adverse emotional effect, with three expressing ‘intolerance’. In this study, 22 per cent of cochlear implantees experienced musical ear syndrome. These symptoms affected patients’ emotional state, but most coped well. Musical ear syndrome can occur prior to and after cochlear implantation.

Importance of cochlear health for implant function.

PubMed

Pfingst, Bryan E; Zhou, Ning; Colesa, Deborah J; Watts, Melissa M; Strahl, Stefan B; Garadat, Soha N; Schvartz-Leyzac, Kara C; Budenz, Cameron L; Raphael, Yehoash; Zwolan, Teresa A

2015-04-01

Amazing progress has been made in providing useful hearing to hearing-impaired individuals using cochlear implants, but challenges remain. One such challenge is understanding the effects of partial degeneration of the auditory nerve, the target of cochlear implant stimulation. Here we review studies from our human and animal laboratories aimed at characterizing the health of the implanted cochlea and the auditory nerve. We use the data on cochlear and neural health to guide rehabilitation strategies. The data also motivate the development of tissue-engineering procedures to preserve or build a healthy cochlea and improve performance obtained by cochlear implant recipients or eventually replace the need for a cochlear implant. This article is part of a Special Issue entitled . Copyright © 2014 Elsevier B.V. All rights reserved.

Physiopathology of the cochlear microcirculation.

PubMed

Shi, Xiaorui

2011-12-01

Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature. Published by Elsevier B.V.

Physiopathology of the Cochlear Microcirculation

PubMed Central

Shi, Xiaorui

2011-01-01

Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature. PMID:21875658

Interactions of speaking condition and auditory feedback on vowel production in postlingually deaf adults with cochlear implants.

PubMed

Ménard, Lucie; Polak, Marek; Denny, Margaret; Burton, Ellen; Lane, Harlan; Matthies, Melanie L; Marrone, Nicole; Perkell, Joseph S; Tiede, Mark; Vick, Jennell

2007-06-01

This study investigates the effects of speaking condition and auditory feedback on vowel production by postlingually deafened adults. Thirteen cochlear implant users produced repetitions of nine American English vowels prior to implantation, and at one month and one year after implantation. There were three speaking conditions (clear, normal, and fast), and two feedback conditions after implantation (implant processor turned on and off). Ten normal-hearing controls were also recorded once. Vowel contrasts in the formant space (expressed in mels) were larger in the clear than in the fast condition, both for controls and for implant users at all three time samples. Implant users also produced differences in duration between clear and fast conditions that were in the range of those obtained from the controls. In agreement with prior work, the implant users had contrast values lower than did the controls. The implant users' contrasts were larger with hearing on than off and improved from one month to one year postimplant. Because the controls and implant users responded similarly to a change in speaking condition, it is inferred that auditory feedback, although demonstrably important for maintaining normative values of vowel contrasts, is not needed to maintain the distinctiveness of those contrasts in different speaking conditions.

Working memory in Farsi-speaking children with normal development and cochlear implant.

PubMed

Soleymani, Zahra; Amidfar, Meysam; Dadgar, Hooshang; Jalaie, Shohre

2014-04-01

Working memory has an important role in language acquisition and development of cognition skills. The ability of encoding, storage and retrieval of phonological codes, as activities of working memory, acquired by audition sense. Children with cochlear implant experience a period that they are not able to perceive sounds. In order to assess the effect of hearing on working memory, we investigated working memory as a cognition skill in children with normal development and cochlear implant. Fifty students with normal hearing and 50 students with cochlear implant aged 5-7 years participated in this study. Children educated in the preschool, the first and second grades. Children with normal development were matched based on age, gender, and grade of education with cochlear implant. Two components of working memory including phonological loop and central executive were compared between two groups. Phonological loop assessed by nonword repetition task and forward digit span. To assess central executive component backward digit span was used. The developmental trend was studied in children with normal development and cochlear implant as well. The effect of age at implantation in children with cochlear implants on components of working memory was investigated. There are significant differences between children with normal development and cochlear implant in all tasks that assess working memory (p < 0.001). The children's age at implantation was negatively correlated with all tasks (p < 0.001). In contrast, duration of usage of cochlear implant set was positively correlated with all tasks (p < 0.001). The comparison of working memory between different grades showed significant differences both in children with normal development and in children with cochlear implant (p < 0.05). These results implied that children with cochlear implant may experience difficulties in working memory. Therefore, these children have problems in encoding, practicing, and repeating phonological units. The results also suggested working memory develops when the child grows up. In cochlear implant children, with decreasing age at implantation and increasing their experience in perceiving sound, working memory skills improved. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Lack of financial barriers to pediatric cochlear implantation: impact of socioeconomic status on access and outcomes.

PubMed

Chang, David T; Ko, Alvin B; Murray, Gail S; Arnold, James E; Megerian, Cliff A

2010-07-01

(1) To analyze if socioeconomic status influences access to cochlear implantation in an environment with adequate Medicaid reimbursement. (2) To determine the impact of socioeconomic status on outcomes after unilateral cochlear implantation. Retrospective cohort study. University Hospitals Case Medical Center and Rainbow Babies and Children's Hospital (tertiary referral center), Cleveland, Ohio. Pediatric patients (age range, newborn to 18 years) who received unilateral cochlear implantation during the period 1996 to 2008. Access to cochlear implantation after referral to a cochlear implant center, postoperative complications, compliance with follow-up appointments, and access to sequential bilateral cochlear implantation. A total of 133 pediatric patients were included in this study; 64 were Medicaid-insured patients and 69 were privately insured patients. There was no statistical difference in the odds of initial cochlear implantation, age at referral, or age at implantation between the 2 groups. The odds of prelingual Medicaid-insured patients receiving sequential bilateral cochlear implantation was less than half that of the privately insured group (odds ratio [OR], 0.43; P = .03). The odds of complications in Medicaid-insured children were almost 5-fold greater than the odds for privately insured children (OR, 4.6; P = .03). There were 10 complications in 51 Medicaid-insured patients (19.6%) as opposed to 3 in 61 privately insured patients (4.9%). Medicaid-insured patients missed substantially more follow-up appointments overall (35% vs 23%) and more consecutive visits (1.9 vs 1.1) compared with privately insured patients. In an environment with adequate Medicaid reimbursement, eligible children have equal access to cochlear implantation, regardless of socioeconomic background. However, lower socioeconomic background is associated with higher rates of postoperative complications, worse follow-up compliance, and lower rates of sequential bilateral implantation, observed herein in Medicaid-insured patients. These findings present opportunities for cochlear implant centers to create programs to address such downstream disparities.

Benefit and predictive factors for speech perception outcomes in pediatric bilateral cochlear implant recipients.

PubMed

Chang, Young-Soo; Hong, Sung Hwa; Kim, Eun Yeon; Choi, Ji Eun; Chung, Won-Ho; Cho, Yang-Sun; Moon, Il Joon

2018-05-18

Despite recent advancement in the prediction of cochlear implant outcome, the benefit of bilateral procedures compared to bimodal stimulation and how we predict speech perception outcomes of sequential bilateral cochlear implant based on bimodal auditory performance in children remain unclear. This investigation was performed: (1) to determine the benefit of sequential bilateral cochlear implant and (2) to identify the associated factors for the outcome of sequential bilateral cochlear implant. Observational and retrospective study. We retrospectively analyzed 29 patients with sequential cochlear implant following bimodal-fitting condition. Audiological evaluations were performed; the categories of auditory performance scores, speech perception with monosyllable and disyllables words, and the Korean version of Ling. Audiological evaluations were performed before sequential cochlear implant with the bimodal fitting condition (CI1+HA) and one year after the sequential cochlear implant with bilateral cochlear implant condition (CI1+CI2). The good Performance Group (GP) was defined as follows; 90% or higher in monosyllable and bisyllable tests with auditory-only condition or 20% or higher improvement of the scores with CI1+CI2. Age at first implantation, inter-implant interval, categories of auditory performance score, and various comorbidities were analyzed by logistic regression analysis. Compared to the CI1+HA, CI1+CI2 provided significant benefit in categories of auditory performance, speech perception, and Korean version of Ling results. Preoperative categories of auditory performance scores were the only associated factor for being GP (odds ratio=4.38, 95% confidence interval - 95%=1.07-17.93, p=0.04). The children with limited language development in bimodal condition should be considered as the sequential bilateral cochlear implant and preoperative categories of auditory performance score could be used as the predictor in speech perception after sequential cochlear implant. Copyright © 2018 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

A comparison of speech intonation production and perception abilities of Farsi speaking cochlear implanted and normal hearing children.

PubMed

Moein, Narges; Khoddami, Seyyedeh Maryam; Shahbodaghi, Mohammad Rahim

2017-10-01

Cochlear implant prosthesis facilitates spoken language development and speech comprehension in children with severe-profound hearing loss. However, this prosthesis is limited in encoding information about fundamental frequency and pitch that are essentially for recognition of speech prosody. The purpose of the present study is to investigate the perception and production of intonation in cochlear implant children and comparison with normal hearing children. This study carried out on 25 cochlear implanted children and 50 children with normal hearing. First, using 10 action pictures statements and questions sentences were extracted. Fundamental frequency and pitch changes were identified using Praat software. Then, these sentences were judged by 7 adult listeners. In second stage 20 sentences were played for child and he/she determined whether it was in a question form or statement one. Performance of cochlear implanted children in perception and production of intonation was significantly lower than children with normal hearing. The difference between fundamental frequency and pitch changes in cochlear implanted children and children with normal hearing was significant (P < 0/05). Cochlear implanted children performance in perception and production of intonation has significant correlation with child's age surgery and duration of prosthesis use (P < 0/05). The findings of the current study show that cochlear prostheses have limited application in facilitating the perception and production of intonation in cochlear implanted children. It should be noted that the child's age at the surgery and duration of prosthesis's use is important in reduction of this limitation. According to these findings, speech and language pathologists should consider intervention of intonation in treatment program of cochlear implanted children. Copyright © 2017 Elsevier B.V. All rights reserved.

The Role of MRI in Diagnosing Neurovascular Compression of the Cochlear Nerve Resulting in Typewriter Tinnitus.

PubMed

Bae, Y J; Jeon, Y J; Choi, B S; Koo, J-W; Song, J-J

2017-06-01

Typewriter tinnitus, a symptom characterized by paroxysmal attacks of staccato sounds, has been thought to be caused by neurovascular compression of the cochlear nerve, but the correlation between radiologic evidence of neurovascular compression of the cochlear nerve and symptom presentation has not been thoroughly investigated. The purpose of this study was to examine whether radiologic evidence of neurovascular compression of the cochlear nerve is pathognomonic in typewriter tinnitus. Fifteen carbamazepine-responding patients with typewriter tinnitus and 8 control subjects were evaluated with a 3D T2-weighted volume isotropic turbo spin-echo acquisition sequence. Groups 1 (16 symptomatic sides), 2 (14 asymptomatic sides), and 3 (16 control sides) were compared with regard to the anatomic relation between the vascular loop and the internal auditory canal and the presence of neurovascular compression of the cochlear nerve with/without angulation/indentation. The anatomic location of the vascular loop was not significantly different among the 3 groups (all, P > .05). Meanwhile, neurovascular compression of the cochlear nerve on MR imaging was significantly higher in group 1 than in group 3 ( P = .032). However, considerable false-positive (no symptoms with neurovascular compression of the cochlear nerve on MR imaging) and false-negative (typewriter tinnitus without demonstrable neurovascular compression of the cochlear nerve) findings were also observed. Neurovascular compression of the cochlear nerve was more frequently detected on the symptomatic side of patients with typewriter tinnitus compared with the asymptomatic side of these patients or on both sides of control subjects on MR imaging. However, considering false-positive and false-negative findings, meticulous history-taking and the response to the initial carbamazepine trial should be regarded as more reliable diagnostic clues than radiologic evidence of neurovascular compression of the cochlear nerve. © 2017 by American Journal of Neuroradiology.

Visualizing Cochlear Mechanics Using Confocal Microscopy

NASA Astrophysics Data System (ADS)

Ulfendahl, M.; Boutet de Monvel, J.; Fridberger, A.

2003-02-01

The sound-evoked vibration pattern of the hearing organ is based on complex mechanical interactions between different cellular structures. To explore the structural changes occurring within the organ of Corti during basilar-membrane motion, stepwise alterations of the scala tympani pressure were applied in an in vitro preparation of the guinea-pig temporal bone. Confocal images were acquired at each pressure level. In this way, the motion of several structures could be simultaneously observed with high resolution in a nearly intact system. Images were analyzed using a novel wavelet-based optical-flow estimation algorithm. Under the present experimental conditions, the reticular lamina moved as a stiff plate with a center of rotation in the region of the inner hair cells. The outer hair cells appeared non-rigid and the basal, synaptic regions of these cells displayed significant radial motion indicative of cellular bending and internal shearing.

Trends in cochlear implants.

PubMed

Zeng, Fan-Gang

2004-01-01

More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic aspects of cochlear implants, focusing on their psychophysical, speech, music, and cognitive performance. This report also forecasts clinical and research trends related to presurgical evaluation, fitting protocols, signal processing, and postsurgical rehabilitation in cochlear implants. Finally, a future landscape in amplification is presented that requires a unique, yet complementary, contribution from hearing aids, middle ear implants, and cochlear implants to achieve a total solution to the entire spectrum of hearing loss treatment and management.

Response Properties of Cochlear Nucleus Neurons in Monkeys

PubMed Central

Roth, G. Linn; Recio, A.

2009-01-01

Much of what is known about how the cochlear nuclei participate in mammalian hearing comes from studies of non-primate mammalian species. To determine to what extent the cochlear nuclei of primates resemble those of other mammalian orders, we have recorded responses to sound in three primate species: marmosets, Cynomolgus macaques, and squirrel monkeys. These recordings show that the same types of temporal firing patterns are found in primates that have been described in other mammals. Responses to tones of neurons in the ventral cochlear nucleus have similar tuning, latencies, post-stimulus time and interspike interval histograms as those recorded in non-primate cochlear nucleus neurons. In the dorsal cochlear nucleus, too, responses were similar. From these results it is evident that insights gained from non-primate studies can be applied to the peripheral auditory system of primates. PMID:19531377

Comparison of Social Interaction between Cochlear-Implanted Children with Normal Intelligence Undergoing Auditory Verbal Therapy and Normal-Hearing Children: A Pilot Study.

PubMed

Monshizadeh, Leila; Vameghi, Roshanak; Sajedi, Firoozeh; Yadegari, Fariba; Hashemi, Seyed Basir; Kirchem, Petra; Kasbi, Fatemeh

2018-04-01

A cochlear implant is a device that helps hearing-impaired children by transmitting sound signals to the brain and helping them improve their speech, language, and social interaction. Although various studies have investigated the different aspects of speech perception and language acquisition in cochlear-implanted children, little is known about their social skills, particularly Persian-speaking cochlear-implanted children. Considering the growing number of cochlear implants being performed in Iran and the increasing importance of developing near-normal social skills as one of the ultimate goals of cochlear implantation, this study was performed to compare the social interaction between Iranian cochlear-implanted children who have undergone rehabilitation (auditory verbal therapy) after surgery and normal-hearing children. This descriptive-analytical study compared the social interaction level of 30 children with normal hearing and 30 with cochlear implants who were conveniently selected. The Raven test was administered to the both groups to ensure normal intelligence quotient. The social interaction status of both groups was evaluated using the Vineland Adaptive Behavior Scale, and statistical analysis was performed using Statistical Package for Social Sciences (SPSS) version 21. After controlling age as a covariate variable, no significant difference was observed between the social interaction scores of both the groups (p > 0.05). In addition, social interaction had no correlation with sex in either group. Cochlear implantation followed by auditory verbal rehabilitation helps children with sensorineural hearing loss to have normal social interactions, regardless of their sex.

Effects of residual hearing on cochlear implant outcomes in children: A systematic-review.

PubMed

Chiossi, Julia Santos Costa; Hyppolito, Miguel Angelo

2017-09-01

to investigate if preoperative residual hearing in prelingually deafened children can interfere on cochlear implant indication and outcomes. a systematic-review was conducted in five international databases up to November-2016, to locate articles that evaluated cochlear implantation in children with some degree of preoperative residual hearing. Outcomes were auditory, language and cognition performances after cochlear implant. The quality of the studies was assessed and classified according to the Oxford Levels of Evidence table - 2011. Risk of biases were also described. From the 30 articles reviewed, two types of questions were identified: (a) what are the benefits of cochlear implantation in children with residual hearing? (b) is the preoperative residual hearing a predictor of cochlear implant outcome? Studies ranged from 04 to 188 subjects, evaluating populations between 1.8 and 10.3 years old. The definition of residual hearing varied between studies. The majority of articles (n = 22) evaluated speech perception as the outcome and 14 also assessed language and speech production. There is evidence that cochlear implant is beneficial to children with residual hearing. Preoperative residual hearing seems to be valuable to predict speech perception outcomes after cochlear implantation, even though the mechanism of how it happens is not clear. More extensive researches must be conducted in order to make recommendations and to set prognosis for cochlear implants based on children preoperative residual hearing. Copyright © 2017 Elsevier B.V. All rights reserved.

REGULATED VESICULAR TRAFFICKING OF SPECIFIC PCDH15 AND VLGR1 VARIANTS IN AUDITORY HAIR CELLS

PubMed Central

Zallocchi, Marisa; Delimont, Duane; Meehan, Daniel T.; Cosgrove, Dominic

2012-01-01

Usher syndrome is a genetically heterogeneous disorder characterized by hearing and balance dysfunction and progressive retinitis pigmentosa. Mouse models carrying mutations for the nine Usher-associated genes have splayed stereocilia and some show delayed maturation of ribbon synapses suggesting these proteins may play different roles in terminal differentiation of auditory hair cells. The presence of the Usher proteins at the basal and apical aspects of the neurosensory epithelia suggests the existence of regulated trafficking through specific transport proteins and routes. Immature mouse cochleae and UB/OC-1 cells were used in this work to address whether specific variants of PCDH15 and VLGR1 are being selectively transported to opposite poles of the hair cells. Confocal co-localization studies between apical and basal vesicular markers and the different PCDH15 and VLGR1 variants along with sucrose density gradients and the use of vesicle trafficking inhibitors show the existence of Usher protein complexes in at least two vesicular sub-pools. The apically trafficked pool co-localized with the early endosomal vesicle marker, rab5, while the basally trafficked pool associates with membrane microdomains and SNAP25. Moreover, co-immunoprecipitation experiments between SNAP25 and VLGR1 show a physical interaction of these two proteins in organ of Corti and brain. Collectively, these findings establish the existence of a differential vesicular trafficking mechanism for specific Usher protein variants in mouse cochlear hair cells, with the apical variants playing a potential role in endosomal recycling and stereocilia development/maintenance and the basolateral variants involved in vesicle docking and/or fusion through SNAP25-mediated interactions. PMID:23035094

Use of suprathreshold stochastic resonance in cochlear implant coding

NASA Astrophysics Data System (ADS)

Allingham, David; Stocks, Nigel G.; Morse, Robert P.

2003-05-01

In this article we discuss the possible use of a novel form of stochastic resonance, termed suprathreshold stochastic resonance (SSR), to improve signal encoding/transmission in cochlear implants. A model, based on the leaky-integrate-and-fire (LIF) neuron, has been developed from physiological data and use to model information flow in a population of cochlear nerve fibers. It is demonstrated that information flow can, in principle, be enhanced by the SSR effect. Furthermore, SSR was found to enhance information transmission for signal parameters that are commonly encountered in cochlear implants. This, therefore, gives hope that SSR may be implemented in cochlear implants to improve speech comprehension.

Prevention of Noise Damage to Cochlear Synapses

DTIC Science & Technology

2015-10-01

AWARD NUMBER: W81XWH-14-1-0494 TITLE: Prevention of Noise Damage to Cochlear Synapses PRINCIPAL INVESTIGATOR: Steven Green CONTRACTING...to Cochlear Synapses 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-14-1-0494 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Steven Green 5d. PROJECT...ABSTRACT Noise-induced synaptopathy is the result of excitotoxic trauma to cochlear synapses due to glutamate released from the hair cells. Excitotoxic

Preventing Ototoxic Synergy of Prior Noise Trauma During Aminoglycoside Therapy

DTIC Science & Technology

2015-12-01

cochlear blood flow . Hearing Research 313, 38-46 (2014). 12. Koo, J.-W. et al. Endotoxemia-mediated inflammation potentiates cochlear uptake of...event in response to a need for higher cochlear blood flow . A 3.7% dilation was adequate for a 20% increase of blood flow 10. On the contrary...summation of the two insults. We have found that prior sound exposure enhances cochlear uptake of aminoglycosides, providing a mechanistic basis for the

Hearing rehabilitation with a binaural cochlear implant in a patient with Erdheim-Chester disease.

PubMed

Querat, Charlotte; Thai-Van, Hung; Durand, Denis Vital; Cotton, François; Gallego, Stéphane; Truy, Eric

2015-09-01

Erdheim-Chester disease (ECD) is a rare non-Langerhans form of histiocytosis. This paper reports an exceptional case of bilateral neural involvement, responsible for profound hearing loss. Bilateral cochlear implantation was performed. We present a 57-year-old man affected by ECD with profound bilateral hearing loss. The patient underwent cochlear implantation with a binaural Digisonic(®) cochlear implant, 7 years after the initial diagnosis. Speech intelligibility rose to a plateau after about 6 months of cochlear implant use. The average outcome of speech intelligibility over time was 55% for dissyllabic words without lip reading, and 70% for sentences. Perception score decreased before the patient died from ECD. A description of the ECD and its otological manifestations is presented. This paper reports the effective hearing rehabilitation of profound bilateral hearing loss by the means of a binaural Digisonic(®) cochlear implant.

Spiral Form of the Human Cochlea Results from Spatial Constraints.

PubMed

Pietsch, M; Aguirre Dávila, L; Erfurt, P; Avci, E; Lenarz, T; Kral, A

2017-08-08

The human inner ear has an intricate spiral shape often compared to shells of mollusks, particularly to the nautilus shell. It has inspired many functional hearing theories. The reasons for this complex geometry remain unresolved. We digitized 138 human cochleae at microscopic resolution and observed an astonishing interindividual variability in the shape. A 3D analytical cochlear model was developed that fits the analyzed data with high precision. The cochlear geometry neither matched a proposed function, namely sound focusing similar to a whispering gallery, nor did it have the form of a nautilus. Instead, the innate cochlear blueprint and its actual ontogenetic variants were determined by spatial constraints and resulted from an efficient packing of the cochlear duct within the petrous bone. The analytical model predicts well the individual 3D cochlear geometry from few clinical measures and represents a clinical tool for an individualized approach to neurosensory restoration with cochlear implants.

Trends in Cochlear Implants

PubMed Central

Zeng, Fan-Gang

2004-01-01

More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic aspects of cochlear implants, focusing on their psychophysical, speech, music, and cognitive performance. This report also forecasts clinical and research trends related to presurgical evaluation, fitting protocols, signal processing, and postsurgical rehabilitation in cochlear implants. Finally, a future landscape in amplification is presented that requires a unique, yet complementary, contribution from hearing aids, middle ear implants, and cochlear implants to achieve a total solution to the entire spectrum of hearing loss treatment and management. PMID:15247993

Ion flow in cochlear hair cells and the regulation of hearing sensitivity.

PubMed

Patuzzi, Robert

2011-10-01

This paper discusses how ion transport proteins in the hair cells of the mammalian cochlea work to produce a sensitive but stable hearing organ. The transport proteins in the inner and outer hair cells are summarized (including their current voltage characteristics), and the roles of these proteins in determining intracellular Ca(2+), membrane potential, and ultimately cochlear sensitivity are discussed. The paper also discusses the role of the Ca(2+) sequestration sacs in outer hair cells in the autoregulation of hair cell membrane potential and cochlear gain, and how the underdamped control of Ca(2+) within these sacs may produce the observed slow oscillations in cochlear sensitivity and otoacoustic emissions after cochlear perturbations, including perilymphatic perfusions and prolonged low-frequency tones. The relative insensitivity of cochlear gain to short-term changes in the endocochlear potential is also discussed. Copyright © 2011 Elsevier B.V. All rights reserved.

The Hearing Outcomes of Cochlear Implantation in Waardenburg Syndrome.

PubMed

Koyama, Hajime; Kashio, Akinori; Sakata, Aki; Tsutsumiuchi, Katsuhiro; Matsumoto, Yu; Karino, Shotaro; Kakigi, Akinobu; Iwasaki, Shinichi; Yamasoba, Tatsuya

2016-01-01

Objectives. This study aimed to determine the feasibility of cochlear implantation for sensorineural hearing loss in patients with Waardenburg syndrome. Method. A retrospective chart review was performed on patients who underwent cochlear implantation at the University of Tokyo Hospital. Clinical classification, genetic mutation, clinical course, preoperative hearing threshold, high-resolution computed tomography of the temporal bone, and postoperative hearing outcome were assessed. Result. Five children with Waardenburg syndrome underwent cochlear implantation. The average age at implantation was 2 years 11 months (ranging from 1 year 9 months to 6 years 3 months). Four patients had congenital profound hearing loss and one patient had progressive hearing loss. Two patients had an inner ear malformation of cochlear incomplete partition type 2. No surgical complication or difficulty was seen in any patient. All patients showed good hearing outcome postoperatively. Conclusion. Cochlear implantation could be a good treatment option for Waardenburg syndrome.

The Hearing Outcomes of Cochlear Implantation in Waardenburg Syndrome

PubMed Central

Koyama, Hajime; Kashio, Akinori; Sakata, Aki; Tsutsumiuchi, Katsuhiro; Matsumoto, Yu; Karino, Shotaro; Kakigi, Akinobu; Iwasaki, Shinichi; Yamasoba, Tatsuya

2016-01-01

Objectives. This study aimed to determine the feasibility of cochlear implantation for sensorineural hearing loss in patients with Waardenburg syndrome. Method. A retrospective chart review was performed on patients who underwent cochlear implantation at the University of Tokyo Hospital. Clinical classification, genetic mutation, clinical course, preoperative hearing threshold, high-resolution computed tomography of the temporal bone, and postoperative hearing outcome were assessed. Result. Five children with Waardenburg syndrome underwent cochlear implantation. The average age at implantation was 2 years 11 months (ranging from 1 year 9 months to 6 years 3 months). Four patients had congenital profound hearing loss and one patient had progressive hearing loss. Two patients had an inner ear malformation of cochlear incomplete partition type 2. No surgical complication or difficulty was seen in any patient. All patients showed good hearing outcome postoperatively. Conclusion. Cochlear implantation could be a good treatment option for Waardenburg syndrome. PMID:27376080

Should children who use cochlear implants wear hearing aids in the opposite ear?

PubMed

Ching, T Y; Psarros, C; Hill, M; Dillon, H; Incerti, P

2001-10-01

The aim of this study was to investigate 1) whether a hearing aid needs to be adjusted differently depending on whether a child wears a cochlear implant or another hearing aid in the contralateral ear; 2) whether the use of a hearing aid and a cochlear implant in opposite ears leads to binaural interference; and 3) whether the use of a hearing aid and a cochlear implant in opposite ears leads to binaural benefits in speech perception, localization, and communicative functioning in real life. Sixteen children participated in this study. All children used a Nucleus 22 or Nucleus 24 cochlear implant system programmed with the SPEAK strategy in one ear. The hearing aid amplification requirements in the nonimplanted ear of these children were determined using two procedures. A paired comparison technique was used to identify the frequency response that was best for speech intelligibility in quiet, and a loudness balancing technique was used to match the loudness of speech in the ear with a hearing aid to that with a cochlear implant. Eleven of the 16 children participated in the investigation of binaural effects. Performance in speech perception, localization, and communicative functioning was assessed under four aided conditions: cochlear implant with hearing aid as worn, cochlear implant alone, hearing aid alone, and cochlear implant with hearing aid adjusted according to individual requirements. Fifteen of the 16 children whose amplification requirements were determined preferred a hearing aid frequency response that was within +/-6 dB/octave of the NAL-RP prescription. On average, the children required 6 dB more gain than prescribed to balance the loudness of the implanted ear for a speech signal presented at 65 dB SPL. For all 11 children whose performance was evaluated for investigating binaural effects, there was no indication of significantly poorer performance under bilaterally aided conditions compared with unilaterally aided conditions. On average, there were significant benefits in speech perception, localization, and aural/oral function when the children used cochlear implants with adjusted hearing aids than when they used cochlear implants alone. All individuals showed benefits in at least one of the measures. Hearing aids for children who also use cochlear implants can be selected using the NAL-RP prescription. Adjustment of hearing aid gain to match loudness in the implanted ear can facilitate integration of signals from both ears, leading to better speech perception. Given that there are binaural advantages from using cochlear implants with hearing aids in opposite ears, clinicians should advise parents and other professionals about these potential advantages, and facilitate bilateral amplification by adjusting hearing aids after stable cochlear implant MAPs are established.

An Antioxidant Screen Identifies Candidates for Protection of Cochlear Hair Cells from Gentamicin Toxicity

PubMed Central

Noack, Volker; Pak, Kwang; Jalota, Rahul; Kurabi, Arwa; Ryan, Allen F.

2017-01-01

Reactive oxygen species are important elements in ototoxic damage to hair cells (HCs), appearing early in the damage process. Higher levels of natural antioxidants are positively correlated with resistance to ototoxins and many studies have shown that exogenous antioxidants can protect HCs from damage. While a very wide variety of antioxidants with different characteristics and intracellular targets exist, most ototoxicity studies have focused upon one or a few well-characterized compounds. Relatively little research has attempted to determine the comparative efficacy of large variety of different antioxidants. This has been in part due to the lack of translation between cell culture and in vivo measures of efficacy. To circumvent this limitation, we used an in vitro assay based on micro-explants from the basal and middle turns of the neonatal mouse organ of Corti to screen a commercial redox library of diverse antioxidant compounds for their ability to protect mammalian HCs from a high dose of the ototoxic antibiotic gentamicin. The library included several antioxidants that have previously been studied as potential treatments for HC damage, as well as many antioxidants that have never been applied to ototoxicity. The micro-explants were treated with 200 μM gentamicin alone, gentamicin plus one of three dosages of a redox compound, the highest dosage of compound alone, or were untreated. HC counts were determined before the gentamicin insult and at 1, 2, and 3 days afterward to evaluate the HC survival. From a total of 81 antioxidant compounds, 13 exhibited significant protection of HCs. These included members of a variety of antioxidant classes with several novel antioxidants, not previously tested on HCs, appearing to alleviate the damaging gentamicin effect. Some compounds previously shown to be protective of HCs were correspondingly protective in this in vitro screen, while others were not. Finally, one of the three pro-oxidant compounds included in the library as well as six antioxidants exhibited evidence of toxicity in the absence of gentamicin. The results demonstrate the wide variability in the ability of antioxidants to protect HCs from high-dose gentamicin damage, and identify promising candidate leads for further study as potential drug targets. Highlights • A medium-throughput assay based on micro-explants of the organ of Corti was developed to screen mammalian cochlear hair cells for protection from damage by ototoxins. • Eighty one antioxidants and 3 pro-oxidants were evaluated for hair cell protection from high-dose gentamicin. • Thirteen antioxidants were significantly protective, while 6 proved to be damaging. • The use of a common assay permitted an evaluation of the relative capacity of different antioxidants for the protection of hair cells. PMID:28867994

Effects of central nervous system residua on cochlear implant results in children deafened by meningitis.

PubMed

Francis, Howard W; Pulsifer, Margaret B; Chinnici, Jill; Nutt, Robert; Venick, Holly S; Yeagle, Jennifer D; Niparko, John K

2004-05-01

This study explored factors associated with speech recognition outcomes in postmeningitic deafness (PMD). The results of cochlear implantation may vary in children with PMD because of sequelae that extend beyond the auditory periphery. To determine which factors might be most determinative of outcome of cochlear implantation in children with PMD. Retrospective chart review. A referral center for pediatric cochlear implantation and rehabilitation. Thirty children with cochlear implants who were deafened by meningitis were matched with subjects who were deafened by other causes based on the age at diagnosis, age at cochlear implantation, age at which hearing aids were first used, and method of communication used at home or in the classroom. Speech perception performance within the first 2 years after cochlear implantation and its relationship with presurgical cognitive measures and medical history. There was no difference in the overall cognitive or postoperative speech perception performance between the children with PMD and those deafened by other causes. The presence of postmeningitic hydrocephalus, however, posed greater challenges to the rehabilitation process, as indicated by significantly smaller gains in speech perception and a predilection for behavioral problems. By comparison, cochlear scarring and incomplete electrode insertion had no impact on speech perception results. Although the results demonstrated no significant delay in cognitive or speech perception performance in the PMD group, central nervous system residua, when present, can impede the acquisition of speech perception with a cochlear implant. Central effects associated with PMD may thus impact language learning potential; cognitive and behavioral therapy should be considered in rehabilitative planning and in establishing expectations of outcome.

A Preliminary Investigation of the Air-Bone Gap: Changes in Intracochlear Sound Pressure With Air- and Bone-conducted Stimuli After Cochlear Implantation.

PubMed

Banakis Hartl, Renee M; Mattingly, Jameson K; Greene, Nathaniel T; Jenkins, Herman A; Cass, Stephen P; Tollin, Daniel J

2016-10-01

A cochlear implant electrode within the cochlea contributes to the air-bone gap (ABG) component of postoperative changes in residual hearing after electrode insertion. Preservation of residual hearing after cochlear implantation has gained importance as simultaneous electric-acoustic stimulation allows for improved speech outcomes. Postoperative loss of residual hearing has previously been attributed to sensorineural changes; however, presence of increased postoperative ABG remains unexplained and could result in part from altered cochlear mechanics. Here, we sought to investigate changes to these mechanics via intracochlear pressure measurements before and after electrode implantation to quantify the contribution to postoperative ABG. Human cadaveric heads were implanted with titanium fixtures for bone conduction transducers. Velocities of stapes capitulum and cochlear promontory between the two windows were measured using single-axis laser Doppler vibrometry and fiber-optic sensors measured intracochlear pressures in scala vestibuli and tympani for air- and bone-conducted stimuli before and after cochlear implant electrode insertion through the round window. Intracochlear pressures revealed only slightly reduced responses to air-conducted stimuli consistent with previous literature. No significant changes were noted to bone-conducted stimuli after implantation. Velocities of the stapes capitulum and the cochlear promontory to both stimuli were stable after electrode placement. Presence of a cochlear implant electrode causes alterations in intracochlear sound pressure levels to air, but not bone, conducted stimuli and helps to explain changes in residual hearing noted clinically. These results suggest the possibility of a cochlear conductive component to postoperative changes in hearing sensitivity.

Organ of Corti explants direct tonotopically graded morphology of spiral ganglion neurons in vitro.

PubMed

Smith, Felicia L; Davis, Robin L

2016-08-01

The spiral ganglion is a compelling model system to examine how morphological form contributes to sensory function. While the ganglion is composed mainly of a single class of type I neurons that make simple one-to-one connections with inner hair cell sensory receptors, it has an elaborate overall morphological design. Specific features, such as soma size and axon outgrowth, are graded along the spiral contour of the cochlea. To begin to understand the interplay between different regulators of neuronal morphology, we cocultured neuron explants with peripheral target tissues removed from distinct cochlear locations. Interestingly, these "hair cell microisolates" were capable of both increasing and decreasing neuronal somata size, without adversely affecting survival. Moreover, axon characteristics elaborated de novo by the primary afferents in culture were systematically regulated by the sensory endorgan. Apparent peripheral nervous system (PNS)-like and central nervous system (CNS)-like axonal profiles were established in our cocultures allowing an analysis of putative PNS/CNS axon length ratios. As predicted from the in vivo organization, PNS-like axon bundles elaborated by apical cocultures were longer than their basal counterparts and this phenotype was methodically altered when neuron explants were cocultured with microisolates from disparate cochlear regions. Thus, location-dependent signals within the organ of Corti may set the "address" of neurons within the spiral ganglion, allowing them to elaborate the appropriate tonotopically associated morphological features in order to carry out their signaling function. J. Comp. Neurol. 524:2182-2207, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

The tonotopic map in the embryonic chicken cochlea.

PubMed

Jones, S M; Jones, T A

1995-02-01

The purpose of the present study was to determine the tonotopic map in the chicken cochlea at 19 days of incubation (E19) by obtaining characteristic frequencies (CFs) for primary afferents, labeling the characterized neurons, and documenting their projections to the papilla. The lowest and highest CFs recorded were 188 and 1623 Hz respectively. The embryonic tonotopic map coincided with maps reported for post-hatch chicks. There were no evidence that neurons selective to low frequencies project inappropriately to more basal locations of the embryonic papilla. Linear regression was used to estimate the frequency gradient (b = 0.037 +/- 0.012 In Hz/% [b +/- SEb]) and intercept (In C, where C = 111 Hz) of the semilog plot of frequency versus cochlear position (in % distance from apex). From these estimates the octave distribution was calculated to be 18.7%/octave or 0.58 mm/octave. These quantities were not significantly different from those found in post hatch chickens. We conclude that the tonotopic map of the avian cochlea for CFs between 100 and 1700 Hz is stable and relatively mature from age E19 to post-hatch day 21 (P21). The most striking sign of immaturity in the E19 embryo is the limited range of high CFs. We offer the hypothesis that, between the ages of E19 and P21, improvements in middle ear admittance alone or in combination with functional maturation of the cochlear base may be the principal factors responsible for the appearance of adult-like high CF limits and not an apically shifting tonotopic map.

Symmetric Electrode Spanning Narrows the Excitation Patterns of Partial Tripolar Stimuli in Cochlear Implants.

PubMed

Luo, Xin; Wu, Ching-Chih

2016-12-01

In cochlear implants (CIs), standard partial tripolar (pTP) mode reduces current spread by returning a fraction of the current to two adjacent flanking electrodes within the cochlea. Symmetric electrode spanning (i.e., separating both the apical and basal return electrodes from the main electrode by one electrode) has been shown to increase the pitch of pTP stimuli, when the ratio of intracochlear return current was fixed. To explain the pitch increase caused by symmetric spanning in pTP mode, this study measured the electrical potentials of both standard and symmetrically spanned pTP stimuli on a main electrode EL8 in five CI ears using electrical field imaging (EFI). In addition, the spatial profiles of evoked compound action potentials (ECAP) and the psychophysical forward masking (PFM) patterns were also measured for both stimuli. The EFI, ECAP, and PFM patterns of a given stimulus differed in shape details, reflecting the different levels of auditory processing and different ratios of intracochlear return current across the measurement methods. Compared to the standard pTP stimuli, the symmetrically spanned pTP stimuli significantly reduced the areas under the curves of the normalized EFI and PFM patterns, without shifting the pattern peaks and centroids (both around EL8). The more focused excitation patterns with symmetric spanning may have caused the previously reported pitch increase, due to an interaction between pitch and timbre perception. Being able to reduce the spread of excitation, pTP mode symmetric spanning is a promising stimulation strategy that may further increase spectral resolution and frequency selectivity with CIs.

Effects of the intensity of masking noise on ear canal recorded low-frequency cochlear microphonic waveforms in normal hearing subjects.

PubMed

Zhang, Ming

2014-07-01

Compared to auditory brainstem responses (ABRs), cochlear microphonics (CMs) may be more appropriate to serve as a supplement to the test of otoacoustic emissions (OAEs). Researchers have shown that low-frequency CMs from the apical cochlea are measurable at the tympanic membrane using high-pass masking noise. Our objective is to study the effect of such noise at different intensities on low-frequency CMs recorded at the ear canal, which is not completely known. Six components were involved in this CM measurement including an ear canal electrode (1), a relatively long and low-frequency toneburst (2), and high-pass masking noise at different intensities (3). The rest components include statistical analysis based on multiple human subjects (4), curve modeling based on amplitudes of CM waveforms (CMWs) and noise intensity (5), and a technique based on electrocochleography (ECochG or ECoG) (6). Results show that low-frequency CMWs appeared clearly. The CMW amplitude decreased with an increase in noise level. It decreased first slowly, then faster, and finally slowly again. In conclusion, when masked with high-pass noise, the low-frequency CMs are measurable at the human ear canal. Such noise reduces the low-frequency CM amplitude. The reduction is noise-intensity dependent but not completely linear. The reduction may be caused by the excited basal cochlea which the low-frequency has to travel and pass through. Although not completely clear, six mechanisms related to such reduction are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Facial nerve stimulation associated with cochlear implant use following temporal bone fractures.

PubMed

Espahbodi, Mana; Sweeney, Alex D; Lennon, Kristen J; Wanna, George B

2015-01-01

To describe the incidence and management of patients with facial nerve stimulation (FNS) associated with cochlear implant (CI) use in the setting of a prior temporal bone fracture. One adult CI recipient is reported who experienced implant associated FNS with a history of a temporal bone fracture. Additionally, a literature search was performed to identify similar patients from previous descriptions of CI related FNS. Presence of FNS after implantation and ability to modify implant programming to avoid FNS. The patient in the present report experienced FNS for middle and basal electrodes during intraoperative neural response telemetry (NRT) in the absence of any surgical exposure or manipulation of the facial nerve. FNS was absent during device activation, but it recurred during follow-up programming sessions. However, additional programming has prevented further FNS during regular implant use. Four other patients with FNS after temporal bone fracture were identified from the literature, and the present case represents the one of two cases in which reprogramming allowed for implant use without FNS. CI associated FNS is uncommon in patients with a history of a temporal bone fracture, but it is likely that fracture lines provide a lower impedance pathway to the adjacent facial nerve and thus reduce the threshold for FNS. The present report suggests that, in the setting of a prior temporal bone fracture, NRT is not always a reliable predictor of FNS during implant use, and programming changes can help to mitigate FNS when it occurs. Copyright © 2015 Elsevier Inc. All rights reserved.

The tonotopic map in the embryonic chicken cochlea

NASA Technical Reports Server (NTRS)

Jones, S. M.; Jones, T. A.

1995-01-01

The purpose of the present study was to determine the tonotopic map in the chicken cochlea at 19 days of incubation (E19) by obtaining characteristic frequencies (CFs) for primary afferents, labeling the characterized neurons, and documenting their projections to the papilla. The lowest and highest CFs recorded were 188 and 1623 Hz respectively. The embryonic tonotopic map coincided with maps reported for post-hatch chicks. There were no evidence that neurons selective to low frequencies project inappropriately to more basal locations of the embryonic papilla. Linear regression was used to estimate the frequency gradient (b = 0.037 +/- 0.012 In Hz/% [b +/- SEb]) and intercept (In C, where C = 111 Hz) of the semilog plot of frequency versus cochlear position (in % distance from apex). From these estimates the octave distribution was calculated to be 18.7%/octave or 0.58 mm/octave. These quantities were not significantly different from those found in post hatch chickens. We conclude that the tonotopic map of the avian cochlea for CFs between 100 and 1700 Hz is stable and relatively mature from age E19 to post-hatch day 21 (P21). The most striking sign of immaturity in the E19 embryo is the limited range of high CFs. We offer the hypothesis that, between the ages of E19 and P21, improvements in middle ear admittance alone or in combination with functional maturation of the cochlear base may be the principal factors responsible for the appearance of adult-like high CF limits and not an apically shifting tonotopic map.

The very large G-protein-coupled receptor VLGR1: a component of the ankle link complex required for the normal development of auditory hair bundles.

PubMed

McGee, Joann; Goodyear, Richard J; McMillan, D Randy; Stauffer, Eric A; Holt, Jeffrey R; Locke, Kirsten G; Birch, David G; Legan, P Kevin; White, Perrin C; Walsh, Edward J; Richardson, Guy P

2006-06-14

Sensory hair bundles in the inner ear are composed of stereocilia that can be interconnected by a variety of different link types, including tip links, horizontal top connectors, shaft connectors, and ankle links. The ankle link antigen is an epitope specifically associated with ankle links and the calycal processes of photoreceptors in chicks. Mass spectrometry and immunoblotting were used to identify this antigen as the avian ortholog of the very large G-protein-coupled receptor VLGR1, the product of the Usher syndrome USH2C (Mass1) locus. Like ankle links, Vlgr1 is expressed transiently around the base of developing hair bundles in mice. Ankle links fail to form in the cochleae of mice carrying a targeted mutation in Vlgr1 (Vlgr1/del7TM), and the bundles become disorganized just after birth. FM1-43 [N-(3-triethylammonium)propyl)-4-(4-(dibutylamino)styryl) pyridinium dibromide] dye loading and whole-cell recordings indicate mechanotransduction is impaired in cochlear, but not vestibular, hair cells of early postnatal Vlgr1/del7TM mutant mice. Auditory brainstem recordings and distortion product measurements indicate that these mice are severely deaf by the third week of life. Hair cells from the basal half of the cochlea are lost in 2-month-old Vlgr1/del7TM mice, and retinal function is mildly abnormal in aged mutants. Our results indicate that Vlgr1 is required for formation of the ankle link complex and the normal development of cochlear hair bundles.

Cockayne syndrome and xeroderma pigmentosum

PubMed Central

Rapin, I.; Lindenbaum, Y.; Dickson, D.W.; Kraemer, K.H.; Robbins, J.H.

2015-01-01

Objectives To review genetic variants of Cockayne syndrome (CS) and xeroderma pigmentosum (XP), autosomal recessive disorders of DNA repair that affect the nervous system, and to illustrate them by the first case of xeroderma pigmentosum–Cockayne syndrome (XP-CS) complex to undergo neuropathologic examination. Methods Published reports of clinical, pathologic, and molecular studies of CS, XP neurologic disease, and the XP-CS complex were reviewed, and a ninth case of XP-CS is summarized. Results CS is a multisystem disorder that causes both profound growth failure of the soma and brain and progressive cachexia, retinal, cochlear, and neurologic degeneration, with a leukodystrophy and demyelinating neuropathy without an increase in cancer. XP presents as extreme photosensitivity of the skin and eyes with a 1000-fold increased frequency of cutaneous basal and squamous cell carcinomas and melanomas and a small increase in nervous system neoplasms. Some 20% of patients with XP incur progressive degeneration of previously normally developed neurons resulting in cortical, basal ganglia, cerebellar, and spinal atrophy, cochlear degeneration, and a mixed distal axonal neuropathy. Cultured cells from patients with CS or XP are hypersensitive to killing by ultraviolet (UV) radiation. Both CS and most XP cells have defective DNA nucleotide excision repair of actively transcribing genes; in addition, XP cells have defective repair of the global genome. There are two complementation groups in CS and seven in XP. Patients with the XP-CS complex fall into three XP complementation groups. Despite their XP genotype, six of nine individuals with the XP-CS complex, including the boy we followed up to his death at age 6, had the typical clinically and pathologically severe CS phenotype. Cultured skin and blood cells had extreme sensitivity to killing by UV radiation, DNA repair was severely deficient, post-UV unscheduled DNA synthesis was reduced to less than 5%, and post-UV plasmid mutation frequency was increased. Conclusions The paradoxical lack of parallelism of phenotype to genotype is unexplained in these disorders. Perhaps diverse mutations responsible for UV sensitivity and deficient DNA repair may also produce profound failure of brain and somatic growth, progressive cachexia and premature aging, and tissue-selective neurologic deterioration by their roles in regulation of transcription and repair of endogenous oxidative DNA damage. PMID:11185579

Cochlear implants in Waardenburg syndrome.

PubMed

Cullen, Robert D; Zdanski, Carlton; Roush, Patricia; Brown, Carolyn; Teagle, Holly; Pillsbury, Harold C; Buchman, Craig

2006-07-01

Waardenburg syndrome is an autosomal-dominant syndrome characterized by dystopia canthorum, hyperplasia of the eyebrows, heterochromia irides, a white forelock, and sensorineural hearing loss in 20% to 55% of patients. This patient population accounts for approximately 2% of congenitally deaf children. The purpose of this retrospective case review was to describe the outcomes for those children with Waardenburg syndrome who have undergone cochlear implantation. Pediatric cochlear implant recipients with documented evidence of Waardenburg syndrome underwent retrospective case review. All patients received their cochlear implants at the study institution followed by outpatient auditory habilitation. Charts were reviewed for etiology and duration of deafness, age at time of cochlear implantation, perioperative complications, duration of use, and performance outcomes. Results of standard tests batteries for speech perception and production administered as a part of the patients' auditory habilitation were reviewed. Seven patients with Waardenburg syndrome and cochlear implants were identified. The average age at implantation was 37 months (range, 18-64 months) and the average duration of use was 69 months (range, 12-143 months). All of these patients are active users of their devices and perform very well after implantation. There were no major complications in this small group of patients. Children with congenital sensorineural hearing loss without other comorbidities (e.g., developmental delay, inner ear malformations) perform well when they receive cochlear implantation and auditory habilitation. Patients with Waardenburg syndrome can be expected to have above-average performance after cochlear implantation.

Efficacy of Human Adipose Tissue-Derived Stem Cells on Neonatal Bilirubin Encephalopathy in Rats.

PubMed

Amini, Naser; Vousooghi, Nasim; Hadjighassem, Mahmoudreza; Bakhtiyari, Mehrdad; Mousavi, Neda; Safakheil, Hosein; Jafari, Leila; Sarveazad, Arash; Yari, Abazar; Ramezani, Sara; Faghihi, Faezeh; Joghataei, Mohammad Taghi

2016-05-01

Kernicterus is a neurological syndrome associated with indirect bilirubin accumulation and damages to the basal ganglia, cerebellum and brain stem nuclei particularly the cochlear nucleus. To mimic haemolysis in a rat model such that it was similar to what is observed in a preterm human, we injected phenylhydrazine in 7-day-old rats to induce haemolysis and then infused sulfisoxazole into the same rats at day 9 to block bilirubin binding sites in the albumin. We have investigated the effectiveness of human adiposity-derived stem cells as a therapeutic paradigm for perinatal neuronal repair in a kernicterus animal model. The level of total bilirubin, indirect bilirubin, brain bilirubin and brain iron was significantly increased in the modelling group. There was a significant decreased in all severity levels of the auditory brainstem response test in the two modelling group. Akinesia, bradykinesia and slip were significantly declined in the experience group. Apoptosis in basal ganglia and cerebellum were significantly decreased in the stem cell-treated group in comparison to the vehicle group. All severity levels of the auditory brainstem response tests were significantly decreased in 2-month-old rats. Transplantation results in the substantial alleviation of walking impairment, apoptosis and auditory dysfunction. This study provides important information for the development of therapeutic strategies using human adiposity-derived stem cells in prenatal brain damage to reduce potential sensori motor deficit.

Surgical Management of the Pediatric Cochlear Implant Patient.

ERIC Educational Resources Information Center

Cohen, Seth M.; Haynes, David S.

2003-01-01

This article discusses the surgical management of children receiving cochlear implants. It identifies preoperative considerations to select patients likely to benefit, contraindications, some new surgical techniques, complications, special considerations (otitis media, meningitis, head growth, inner ear malformations, and cochlear obstruction).…

Benefits of Localization and Speech Perception with Multiple Noise Sources in Listeners with a Short-electrode Cochlear Implant

PubMed Central

Dunn, Camille C.; Perreau, Ann; Gantz, Bruce; Tyler, Richard

2009-01-01

Background Research suggests that for individuals with significant low-frequency hearing, implantation of a short-electrode cochlear implant may provide benefits of improved speech perception abilities. Because this strategy combines acoustic and electrical hearing within the same ear while at the same time preserving low-frequency residual acoustic hearing in both ears, localization abilities may also be improved. However, very little research has focused on the localization and spatial hearing abilities of users with a short-electrode cochlear implant. Purpose The purpose of this study was to evaluate localization abilities for listeners with a short-electrode cochlear implant who continue to wear hearing aids in both ears. A secondary purpose was to document speech perception abilities using a speech in noise test with spatially-separate noise sources. Research Design Eleven subjects that utilized a short-electrode cochlear implant and bilateral hearing aids were tested on localization and speech perception with multiple noise locations using an eight-loudspeaker array. Performance was assessed across four listening conditions using various combinations of cochlear implant and/or hearing aid use. Results Results for localization showed no significant difference between using bilateral hearing aids and bilateral hearing aids plus the cochlear implant. However, there was a significant difference between the bilateral hearing aid condition and the implant plus use of a contralateral hearing aid for all eleven subjects. Results for speech perception showed a significant benefit when using bilateral hearing aids plus the cochlear implant over use of the implant plus only one hearing aid. Conclusion Combined use of both hearing aids and the cochlear implant show significant benefits for both localization and speech perception in noise for users with a short-electrode cochlear implant. These results emphasize the importance of low-frequency information in two ears for the purpose of localization and speech perception in noise. PMID:20085199

Benefits of localization and speech perception with multiple noise sources in listeners with a short-electrode cochlear implant.

PubMed

Dunn, Camille C; Perreau, Ann; Gantz, Bruce; Tyler, Richard S

2010-01-01

Research suggests that for individuals with significant low-frequency hearing, implantation of a short-electrode cochlear implant may provide benefits of improved speech perception abilities. Because this strategy combines acoustic and electrical hearing within the same ear while at the same time preserving low-frequency residual acoustic hearing in both ears, localization abilities may also be improved. However, very little research has focused on the localization and spatial hearing abilities of users with a short-electrode cochlear implant. The purpose of this study was to evaluate localization abilities for listeners with a short-electrode cochlear implant who continue to wear hearing aids in both ears. A secondary purpose was to document speech perception abilities using a speech-in-noise test with spatially separate noise sources. Eleven subjects that utilized a short-electrode cochlear implant and bilateral hearing aids were tested on localization and speech perception with multiple noise locations using an eight-loudspeaker array. Performance was assessed across four listening conditions using various combinations of cochlear implant and/or hearing aid use. Results for localization showed no significant difference between using bilateral hearing aids and bilateral hearing aids plus the cochlear implant. However, there was a significant difference between the bilateral hearing aid condition and the implant plus use of a contralateral hearing aid for all 11 subjects. Results for speech perception showed a significant benefit when using bilateral hearing aids plus the cochlear implant over use of the implant plus only one hearing aid. Combined use of both hearing aids and the cochlear implant show significant benefits for both localization and speech perception in noise for users with a short-electrode cochlear implant. These results emphasize the importance of low-frequency information in two ears for the purpose of localization and speech perception in noise.

Quantitative polarized light microscopy of unstained mammalian cochlear sections

NASA Astrophysics Data System (ADS)

Kalwani, Neil M.; Ong, Cheng Ai; Lysaght, Andrew C.; Haward, Simon J.; McKinley, Gareth H.; Stankovic, Konstantina M.

2013-02-01

Hearing loss is the most common sensory deficit in the world, and most frequently it originates in the inner ear. Yet, the inner ear has been difficult to access for diagnosis because of its small size, delicate nature, complex three-dimensional anatomy, and encasement in the densest bone in the body. Evolving optical methods are promising to afford cellular diagnosis of pathologic changes in the inner ear. To appropriately interpret results from these emerging technologies, it is important to characterize optical properties of cochlear tissues. Here, we focus on that characterization using quantitative polarized light microscopy (qPLM) applied to unstained cochlear sections of the mouse, a common animal model of human hearing loss. We find that the most birefringent cochlear materials are collagen fibrils and myelin. Retardance of the otic capsule, the spiral ligament, and the basilar membrane are substantially higher than that of other cochlear structures. Retardance of the spiral ligament and the basilar membrane decrease from the cochlear base to the apex, compared with the more uniform retardance of other structures. The intricate structural details revealed by qPLM of unstained cochlear sections ex vivo strongly motivate future application of polarization-sensitive optical coherence tomography to human cochlea in vivo.

Quantitative polarized light microscopy of unstained mammalian cochlear sections

PubMed Central

Kalwani, Neil M.; Ong, Cheng Ai; Lysaght, Andrew C.; Haward, Simon J.; McKinley, Gareth H.

2013-01-01

Abstract. Hearing loss is the most common sensory deficit in the world, and most frequently it originates in the inner ear. Yet, the inner ear has been difficult to access for diagnosis because of its small size, delicate nature, complex three-dimensional anatomy, and encasement in the densest bone in the body. Evolving optical methods are promising to afford cellular diagnosis of pathologic changes in the inner ear. To appropriately interpret results from these emerging technologies, it is important to characterize optical properties of cochlear tissues. Here, we focus on that characterization using quantitative polarized light microscopy (qPLM) applied to unstained cochlear sections of the mouse, a common animal model of human hearing loss. We find that the most birefringent cochlear materials are collagen fibrils and myelin. Retardance of the otic capsule, the spiral ligament, and the basilar membrane are substantially higher than that of other cochlear structures. Retardance of the spiral ligament and the basilar membrane decrease from the cochlear base to the apex, compared with the more uniform retardance of other structures. The intricate structural details revealed by qPLM of unstained cochlear sections ex vivo strongly motivate future application of polarization-sensitive optical coherence tomography to human cochlea in vivo. PMID:23407909

Glutamate co-transmission from developing medial nucleus of the trapezoid body - Lateral superior olive synapses is cochlear dependent in kanamycin-treated rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jae Ho; Pradhan, Jonu; Maskey, Dhiraj

Research highlights: {yields} Glutamate co-transmission is enhanced in kanamycin-treated rats. {yields} VGLUT3 expression is increased in kanamycin-treated rats. {yields} GlyR expression is decreased in kanamycin-treated rats. {yields} GlyR, VGLUT3 expression patterns are asymmetric in unilaterally cochlear ablated rat. -- Abstract: Cochlear dependency of glutamate co-transmission at the medial nucleus of the trapezoid body (MNTB) - the lateral superior olive (LSO) synapses was investigated using developing rats treated with high dose kanamycin. Rats were treated with kanamycin from postnatal day (P) 3 to P8. A scanning electron microscopic study on P9 demonstrated partial cochlear hair cell damage. A whole cell voltagemore » clamp experiment demonstrated the increased glutamatergic portion of postsynaptic currents (PSCs) elicited by MNTB stimulation in P9-P11 kanamycin-treated rats. The enhanced VGLUT3 immunoreactivities (IRs) in kanamycin-treated rats and asymmetric VGLUT3 IRs in the LSO of unilaterally cochlear ablated rats supported the electrophysiologic data. Taken together, it is concluded that glutamate co-transmission is cochlear-dependent and enhanced glutamate co-transmission in kanamycin-treated rats is induced by partial cochlear damage.« less

Meningitis following cochlear implantation: pathomechanisms, clinical symptoms, conservative and surgical treatments.

PubMed

Arnold, W; Bredberg, G; Gstöttner, W; Helms, J; Hildmann, H; Kiratzidis, T; Müller, J; Ramsden, R T; Roland, P; Walterspiel, J N

2002-01-01

Pneumococcal otogenic meningitis is a rare postsurgical complication that can develop following stapedectomy or after cochlear implantation. The bacterial infection can be fatal in some instances. A recent increase in the incidence of otogenic meningitis among cochlear implant wearers is of concern. The majority of meningitis cases are associated with a 2-component electrode manufactured by one cochlear implant company. The device with the added 'positioner' component has been withdrawn from the market (FDA Public Health Web Notification: Cochlear Implant Recipients may be at Greater Risk for Meningitis, Updated: August 29, 2002, www.fda.gov/cdrh/safety/cochlear.html). Not all cases have been subsequent to otitis media and symptoms have developed from less than 24 h up to a few years after implantation. The purpose of this paper is to review and discuss the pathogenesis, pathology/bacteriology and to elaborate on some clinical features of otogenic meningitis in implanted children and adults. Essential aspects of surgery, electrode design, and cochleostomy seal are discussed. Conclusions are drawn from the available data and recommendations are made for good practice in cochlear implantation and follow-up. Copyright 2002 S. Karger AG, Basel

The development of the Nucleus Freedom Cochlear implant system.

PubMed

Patrick, James F; Busby, Peter A; Gibson, Peter J

2006-12-01

Cochlear Limited (Cochlear) released the fourth-generation cochlear implant system, Nucleus Freedom, in 2005. Freedom is based on 25 years of experience in cochlear implant research and development and incorporates advances in medicine, implantable materials, electronic technology, and sound coding. This article presents the development of Cochlear's implant systems, with an overview of the first 3 generations, and details of the Freedom system: the CI24RE receiver-stimulator, the Contour Advance electrode, the modular Freedom processor, the available speech coding strategies, the input processing options of Smart Sound to improve the signal before coding as electrical signals, and the programming software. Preliminary results from multicenter studies with the Freedom system are reported, demonstrating better levels of performance compared with the previous systems. The final section presents the most recent implant reliability data, with the early findings at 18 months showing improved reliability of the Freedom implant compared with the earlier Nucleus 3 System. Also reported are some of the findings of Cochlear's collaborative research programs to improve recipient outcomes. Included are studies showing the benefits from bilateral implants, electroacoustic stimulation using an ipsilateral and/or contralateral hearing aid, advanced speech coding, and streamlined speech processor programming.

Use of a gentamicin-impregnated collagen sheet (Collatamp(®)) in the management of major soft tissue complications in pediatric cochlear implants.

PubMed

Benito-González, Fernando; Benito, Jose; Sánchez, Luis Alberto Guardado; Estevez Alonso, Santiago; Muñoz Herrera, Angel; Batuecas-Caletrio, Angel

2014-09-01

The objective was to report the effectiveness of salvage treatment in soft tissue infection around cochlear implants with an absorbable gentamicin collagen sheet and a periosteum and skin rotation flaps. Three patients with cochlear implant and persistent surrounding soft tissue infection are included. All of them underwent antibiotic treatment prior to surgery without any response. In this study preoperative and postoperative audiograms were practiced. Surgical excision of infectious skin and a periosteum and skin rotation flaps were performed. The cochlear implant was refixed in the temporal bone and a gentamicin-impregnated collagen sheet was located covering the cochlear implant. headings In all patients with soft tissue infection around the cochlear implant, infection was completely resolved. It was not necessary to remove the device in any case. The use of an absorbable gentamicin-impregnated collagen sheet is not described for the management of soft tissue complications in pediatric cochlear implant patients. The local application of high concentrations of antibiotic administered by this sheet may be effective against resistant bacteria and, in conjunction with surgery, may resolve this type of complications.

Cochlear Implantation after Bilateral Transverse Temporal Bone Fractures

PubMed Central

Shin, Jong-Heon; Park, SooChan; Baek, Sam-Hyun

2008-01-01

Patients deafened by a severe head injury are rarely encountered. We report a case of a 65-yr-old man with bilateral transverse temporal bone fractures due to head injury. He underwent cochlear implant and achieved a satisfactory auditory rehabilitation. Imaging studies of temporal bone before performing a cochlear implantation provide important information on a patient with bilateral temporal bone fractures. Cochlear implantations with careful planning in such a patient may be a very effective method for aural rehabilitation. PMID:19434252

The contribution of short-term memory capacity to reading ability in adolescents with cochlear implants.

PubMed

Edwards, Lindsey; Aitkenhead, Lynne; Langdon, Dawn

2016-11-01

This study aimed to establish the relationship between short-term memory capacity and reading skills in adolescents with cochlear implants. A between-groups design compared a group of young people with cochlear implants with a group of hearing peers on measures of reading, and auditory and visual short-term memory capacity. The groups were matched for non-verbal IQ and age. The adolescents with cochlear implants were recruited from the Cochlear Implant Programme at a specialist children's hospital. The hearing participants were recruited from the same schools as those attended by the implanted adolescents. Participants were 18 cochlear implant users and 14 hearing controls, aged between 12 and 18 years. All used English as their main language and had no significant learning disability or neuro-developmental disorder. Short-term memory capacity was assessed in the auditory modality using Forward and Reverse Digit Span from the WISC IV UK, and visually using Forward and Reverse Memory from the Leiter-R. Individual word reading, reading comprehension and pseudoword decoding were assessed using the WIAT II UK. A series of ANOVAs revealed that the adolescents with cochlear implants had significantly poorer auditory short-term memory capacity and reading skills (on all measures) compared with their hearing peers. However, when Forward Digit Span was entered into the analyses as a covariate, none of the differences remained statistically significant. Deficits in immediate auditory memory persist into adolescence in deaf children with cochlear implants. Short-term auditory memory capacity is an important neurocognitive process in the development of reading skills after cochlear implantation in childhood that remains evident in later adolescence. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

A preliminary investigation of the air-bone gap: Changes in intracochlear sound pressure with air- and bone-conducted stimuli after cochlear implantation

PubMed Central

Banakis Hartl, Renee M.; Mattingly, Jameson K.; Greene, Nathaniel T.; Jenkins, Herman A.; Cass, Stephen P.; Tollin, Daniel J.

2016-01-01

Hypothesis A cochlear implant electrode within the cochlea contributes to the air-bone gap (ABG) component of postoperative changes in residual hearing after electrode insertion. Background Preservation of residual hearing after cochlear implantation has gained importance as simultaneous electric-acoustic stimulation allows for improved speech outcomes. Postoperative loss of residual hearing has previously been attributed to sensorineural changes; however, presence of increased postoperative air-bone gap remains unexplained and could result in part from altered cochlear mechanics. Here, we sought to investigate changes to these mechanics via intracochlear pressure measurements before and after electrode implantation to quantify the contribution to postoperative air-bone gap. Methods Human cadaveric heads were implanted with titanium fixtures for bone conduction transducers. Velocities of stapes capitulum and cochlear promontory between the two windows were measured using single-axis laser Doppler vibrometry and fiber-optic sensors measured intracochlear pressures in scala vestibuli and tympani for air- and bone-conducted stimuli before and after cochlear implant electrode insertion through the round window. Results Intracochlear pressures revealed only slightly reduced responses to air-conducted stimuli consistent with prior literature. No significant changes were noted to bone-conducted stimuli after implantation. Velocities of the stapes capitulum and the cochlear promontory to both stimuli were stable following electrode placement. Conclusion Presence of a cochlear implant electrode causes alterations in intracochlear sound pressure levels to air, but not bone, conducted stimuli and helps to explain changes in residual hearing noted clinically. These results suggest the possibility of a cochlear conductive component to postoperative changes in hearing sensitivity. PMID:27579835

Recognition and localization of speech by adult cochlear implant recipients wearing a digital hearing aid in the nonimplanted ear (bimodal hearing).

PubMed

Potts, Lisa G; Skinner, Margaret W; Litovsky, Ruth A; Strube, Michael J; Kuk, Francis

2009-06-01

The use of bilateral amplification is now common clinical practice for hearing aid users but not for cochlear implant recipients. In the past, most cochlear implant recipients were implanted in one ear and wore only a monaural cochlear implant processor. There has been recent interest in benefits arising from bilateral stimulation that may be present for cochlear implant recipients. One option for bilateral stimulation is the use of a cochlear implant in one ear and a hearing aid in the opposite nonimplanted ear (bimodal hearing). This study evaluated the effect of wearing a cochlear implant in one ear and a digital hearing aid in the opposite ear on speech recognition and localization. A repeated-measures correlational study was completed. Nineteen adult Cochlear Nucleus 24 implant recipients participated in the study. The participants were fit with a Widex Senso Vita 38 hearing aid to achieve maximum audibility and comfort within their dynamic range. Soundfield thresholds, loudness growth, speech recognition, localization, and subjective questionnaires were obtained six-eight weeks after the hearing aid fitting. Testing was completed in three conditions: hearing aid only, cochlear implant only, and cochlear implant and hearing aid (bimodal). All tests were repeated four weeks after the first test session. Repeated-measures analysis of variance was used to analyze the data. Significant effects were further examined using pairwise comparison of means or in the case of continuous moderators, regression analyses. The speech-recognition and localization tasks were unique, in that a speech stimulus presented from a variety of roaming azimuths (140 degree loudspeaker array) was used. Performance in the bimodal condition was significantly better for speech recognition and localization compared to the cochlear implant-only and hearing aid-only conditions. Performance was also different between these conditions when the location (i.e., side of the loudspeaker array that presented the word) was analyzed. In the bimodal condition, the speech-recognition and localization tasks were equal regardless of which side of the loudspeaker array presented the word, while performance was significantly poorer for the monaural conditions (hearing aid only and cochlear implant only) when the words were presented on the side with no stimulation. Binaural loudness summation of 1-3 dB was seen in soundfield thresholds and loudness growth in the bimodal condition. Measures of the audibility of sound with the hearing aid, including unaided thresholds, soundfield thresholds, and the Speech Intelligibility Index, were significant moderators of speech recognition and localization. Based on the questionnaire responses, participants showed a strong preference for bimodal stimulation. These findings suggest that a well-fit digital hearing aid worn in conjunction with a cochlear implant is beneficial to speech recognition and localization. The dynamic test procedures used in this study illustrate the importance of bilateral hearing for locating, identifying, and switching attention between multiple speakers. It is recommended that unilateral cochlear implant recipients, with measurable unaided hearing thresholds, be fit with a hearing aid.

Relationships among Professionals' Knowledge, Experience, and Expectations Regarding Cochlear Implants

ERIC Educational Resources Information Center

Ben-Itzhak, D.; Most, T.; Weisel, A.

2005-01-01

The present study examined the relationships between teachers' and communication clinicians' self-reported knowledge on cochlear implants and their expectations of CIs. The authors also explored these professionals' views regarding the child's communication mode, educational setting, and social options following cochlear implantation. The…

The Relationship between Cochlear Implants and Deaf Identity

ERIC Educational Resources Information Center

Chapman, Madeline; Dammeyer, Jesper

2017-01-01

The degree to which individuals with cochlear implants (CIs) experience communication difficulties has implications for social participation and identity development. However, few studies have examined the relationship between cochlear implantation, identity, and social participation. Using data from a Danish national survey of deaf adults, the…

Changing patterns of peanut agglutinin labelling in the dorsal cochlear nucleus correspond to axonal ingrowth.

PubMed Central

Riggs, G H; Schweitzer, L

1994-01-01

Various studies have suggested that glycoconjugates may influence connectivity and lamination in the developing central nervous system and may function as barriers to neuritic extension. It has been proposed that the peanut agglutinin lectin labels a glycoconjugate subserving a barrier function. We chose to investigate the distribution of this peanut-agglutinin-labelled glycoconjugate in the dorsal cochlear nucleus of the developing hamster since the development of the dorsal cochlear nucleus is well characterised and its axons obey laminar boundaries. The distribution of peanut agglutinin label throughout the cochlear nucleus delineated zones that cochlear axons fail to invade. In the dorsal cochlear nucleus, laminar differences were reduced on postnatal d 13 and virtually disappearing by postnatal d 23. Label in the molecular layer dissipated as axons and dendrites grew into this layer. These patterns of peanut agglutinin binding correspond to axonal ingrowth and are consistent with a barrier function for glycoconjugates in the molecular layer. Images Fig. 1 Fig. 2 Fig. 4 PMID:7961144

Modulation of Mcl-1 expression reduces age-related cochlear degeneration

PubMed Central

Yang, Wei Ping; Xu, Yang; Guo, Wei Wei; Liu, Hui Zhan; Hu, Bo Hua

2013-01-01

Mcl-1 is an anti-apoptotic member of the Bcl-2 family that modulates apoptosis-related signaling pathways and promotes cell survival. We have previously demonstrated a reduction of Mcl-1 expression in aging cochleae. To investigate whether restoring Mcl-1 expression would reduce aging-related cochlear degeneration, we developed a rat model of Mcl-1 overexpression. A plasmid encoding human Mcl-1/enhanced green fluorescent protein was applied to the round window of the cochlea. This in vivo treatment transfected both the sensory and supporting cells of the cochlear sensory epithelium and enhanced Mcl-1 expression at both the mRNA and the protein level. The upregulation of Mcl-1 expression reduced the progression of age-related cochlear dysfunction and sensory cell death. Furthermore, the transfection of Mcl-1 exerted its protective effect by suppressing cochlear apoptosis at the mitochondrial level. This study demonstrates that the genetic modulation of Mcl-1 expression reduces the progression of age-related cochlear degeneration. PMID:23790646

Evidence of across-channel processing for spectral-ripple discrimination in cochlear implant listeners.

PubMed

Won, Jong Ho; Jones, Gary L; Drennan, Ward R; Jameyson, Elyse M; Rubinstein, Jay T

2011-10-01

Spectral-ripple discrimination has been used widely for psychoacoustical studies in normal-hearing, hearing-impaired, and cochlear implant listeners. The present study investigated the perceptual mechanism for spectral-ripple discrimination in cochlear implant listeners. The main goal of this study was to determine whether cochlear implant listeners use a local intensity cue or global spectral shape for spectral-ripple discrimination. The effect of electrode separation on spectral-ripple discrimination was also evaluated. Results showed that it is highly unlikely that cochlear implant listeners depend on a local intensity cue for spectral-ripple discrimination. A phenomenological model of spectral-ripple discrimination, as an "ideal observer," showed that a perceptual mechanism based on discrimination of a single intensity difference cannot account for performance of cochlear implant listeners. Spectral modulation depth and electrode separation were found to significantly affect spectral-ripple discrimination. The evidence supports the hypothesis that spectral-ripple discrimination involves integrating information from multiple channels. © 2011 Acoustical Society of America

Evidence of across-channel processing for spectral-ripple discrimination in cochlear implant listeners a

PubMed Central

Ho Won, Jong; Jones, Gary L.; Drennan, Ward R.; Jameyson, Elyse M.; Rubinstein, Jay T.

2011-01-01

Spectral-ripple discrimination has been used widely for psychoacoustical studies in normal-hearing, hearing-impaired, and cochlear implant listeners. The present study investigated the perceptual mechanism for spectral-ripple discrimination in cochlear implant listeners. The main goal of this study was to determine whether cochlear implant listeners use a local intensity cue or global spectral shape for spectral-ripple discrimination. The effect of electrode separation on spectral-ripple discrimination was also evaluated. Results showed that it is highly unlikely that cochlear implant listeners depend on a local intensity cue for spectral-ripple discrimination. A phenomenological model of spectral-ripple discrimination, as an “ideal observer,” showed that a perceptual mechanism based on discrimination of a single intensity difference cannot account for performance of cochlear implant listeners. Spectral modulation depth and electrode separation were found to significantly affect spectral-ripple discrimination. The evidence supports the hypothesis that spectral-ripple discrimination involves integrating information from multiple channels. PMID:21973363

International classification of reliability for implanted cochlear implant receiver stimulators.

PubMed

Battmer, Rolf-Dieter; Backous, Douglas D; Balkany, Thomas J; Briggs, Robert J S; Gantz, Bruce J; van Hasselt, Andrew; Kim, Chong Sun; Kubo, Takeshi; Lenarz, Thomas; Pillsbury, Harold C; O'Donoghue, Gerard M

2010-10-01

To design an international standard to be used when reporting reliability of the implanted components of cochlear implant systems to appropriate governmental authorities, cochlear implant (CI) centers, and for journal editors in evaluating manuscripts involving cochlear implant reliability. The International Consensus Group for Cochlear Implant Reliability Reporting was assembled to unify ongoing efforts in the United States, Europe, Asia, and Australia to create a consistent and comprehensive classification system for the implanted components of CI systems across manufacturers. All members of the consensus group are from tertiary referral cochlear implant centers. None. A clinically relevant classification scheme adapted from principles of ISO standard 5841-2:2000 originally designed for reporting reliability of cardiac pacemakers, pulse generators, or leads. Standard definitions for device failure, survival time, clinical benefit, reduced clinical benefit, and specification were generated. Time intervals for reporting back to implant centers for devices tested to be "out of specification," categorization of explanted devices, the method of cumulative survival reporting, and content of reliability reports to be issued by manufacturers was agreed upon by all members. The methodology for calculating Cumulative survival was adapted from ISO standard 5841-2:2000. The International Consensus Group on Cochlear Implant Device Reliability Reporting recommends compliance to this new standard in reporting reliability of implanted CI components by all manufacturers of CIs and the adoption of this standard as a minimal reporting guideline for editors of journals publishing cochlear implant research results.

Evaluation of Mandarin Chinese Speech Recognition in Adults with Cochlear Implants Using the Spectral Ripple Discrimination Test

PubMed Central

Dai, Chuanfu; Zhao, Zeqi; Zhang, Duo; Lei, Guanxiong

2018-01-01

Background The aim of this study was to explore the value of the spectral ripple discrimination test in speech recognition evaluation among a deaf (post-lingual) Mandarin-speaking population in China following cochlear implantation. Material/Methods The study included 23 Mandarin-speaking adult subjects with normal hearing (normal-hearing group) and 17 deaf adults who were former Mandarin-speakers, with cochlear implants (cochlear implantation group). The normal-hearing subjects were divided into men (n=10) and women (n=13). The spectral ripple discrimination thresholds between the groups were compared. The correlation between spectral ripple discrimination thresholds and Mandarin speech recognition rates in the cochlear implantation group were studied. Results Spectral ripple discrimination thresholds did not correlate with age (r=−0.19; p=0.22), and there was no significant difference in spectral ripple discrimination thresholds between the male and female groups (p=0.654). Spectral ripple discrimination thresholds of deaf adults with cochlear implants were significantly correlated with monosyllabic recognition rates (r=0.84; p=0.000). Conclusions In a Mandarin Chinese speaking population, spectral ripple discrimination thresholds of normal-hearing individuals were unaffected by both gender and age. Spectral ripple discrimination thresholds were correlated with Mandarin monosyllabic recognition rates of Mandarin-speaking in post-lingual deaf adults with cochlear implants. The spectral ripple discrimination test is a promising method for speech recognition evaluation in adults following cochlear implantation in China. PMID:29806954

Evaluation of Mandarin Chinese Speech Recognition in Adults with Cochlear Implants Using the Spectral Ripple Discrimination Test.

PubMed

Dai, Chuanfu; Zhao, Zeqi; Shen, Weidong; Zhang, Duo; Lei, Guanxiong; Qiao, Yuehua; Yang, Shiming

2018-05-28

BACKGROUND The aim of this study was to explore the value of the spectral ripple discrimination test in speech recognition evaluation among a deaf (post-lingual) Mandarin-speaking population in China following cochlear implantation. MATERIAL AND METHODS The study included 23 Mandarin-speaking adult subjects with normal hearing (normal-hearing group) and 17 deaf adults who were former Mandarin-speakers, with cochlear implants (cochlear implantation group). The normal-hearing subjects were divided into men (n=10) and women (n=13). The spectral ripple discrimination thresholds between the groups were compared. The correlation between spectral ripple discrimination thresholds and Mandarin speech recognition rates in the cochlear implantation group were studied. RESULTS Spectral ripple discrimination thresholds did not correlate with age (r=-0.19; p=0.22), and there was no significant difference in spectral ripple discrimination thresholds between the male and female groups (p=0.654). Spectral ripple discrimination thresholds of deaf adults with cochlear implants were significantly correlated with monosyllabic recognition rates (r=0.84; p=0.000). CONCLUSIONS In a Mandarin Chinese speaking population, spectral ripple discrimination thresholds of normal-hearing individuals were unaffected by both gender and age. Spectral ripple discrimination thresholds were correlated with Mandarin monosyllabic recognition rates of Mandarin-speaking in post-lingual deaf adults with cochlear implants. The spectral ripple discrimination test is a promising method for speech recognition evaluation in adults following cochlear implantation in China.

The Modified Rambo Transcanal Approach for Cochlear Implantation in CHARGE Syndrome.

PubMed

Wick, Cameron C; Moore, Amy M; Killeen, Daniel E; Isaacson, Brandon

2017-10-01

CHARGE syndrome is associated with a variety of temporal bone anomalies and deafness. The lack of surgical landmarks and facial nerve irregularities make cochlear implantation in this population a challenging endeavor. This study aims to describe a safe and efficacious transcanal approach for cochlear implantation that obviates the need to perform a mastoidectomy and facial recess. Three children with profound hearing loss secondary to CHARGE syndrome. Transcanal cochlear implantation with closure of the ear canal via a modified Rambo meatoplasty. Retrospective chart review of temporal bone anomalies associated with CHARGE syndrome, technical nuances of this transcanal approach, and cochlear implant outcomes. The mean patient age was 2.5 years (range 1.5-3.8 yr). Two were male and two were left ears. All patients had a hypoplastic mastoid, semicircular canal aplasia, and had some degree of cochlear dysplasia. A full cochlear implant insertion was achieved in all cases, even in the presence of grossly abnormal middle ear and facial nerve anatomy. There were no intraoperative or postoperative complications. The mean follow-up was 12.4 months (range, 3.9-25.2 mo). All three patients use their device daily. Their guardians report improved vocalization and environmental awareness. The modified Rambo transcanal approach provides a safe corridor for cochlear implantation in patients with CHARGE syndrome. This approach minimizes the anatomical variations associated with the syndrome and may reduce the risk of electrode extrusion. Implant outcomes in this patient population remain highly variable based on the patient's global cognitive capacity.

Early Vocabulary Development in Children with Bilateral Cochlear Implants

ERIC Educational Resources Information Center

Välimaa, Taina; Kunnari, Sari; Laukkanen-Nevala, Päivi; Lonka, Eila

2018-01-01

Background: Children with unilateral cochlear implants (CIs) may have delayed vocabulary development for an extended period after implantation. Bilateral cochlear implantation is reported to be associated with improved sound localization and enhanced speech perception in noise. This study proposed that bilateral implantation might also promote…

Deafblind People's Experiences of Cochlear Implantation

ERIC Educational Resources Information Center

Soper, Janet

2006-01-01

Cochlear implants are electronic devices that create the sensation of hearing in those who cannot obtain any benefit from conventional hearing aids. This article examines the experience of cochlear implantation in a select group of individuals with acquired deafblindness, focusing on three key themes: access to communication, information and…

The benefits of remote microphone technology for adults with cochlear implants.

PubMed

Fitzpatrick, Elizabeth M; Séguin, Christiane; Schramm, David R; Armstrong, Shelly; Chénier, Josée

2009-10-01

Cochlear implantation has become a standard practice for adults with severe to profound hearing loss who demonstrate limited benefit from hearing aids. Despite the substantial auditory benefits provided by cochlear implants, many adults experience difficulty understanding speech in noisy environments and in other challenging listening conditions such as television. Remote microphone technology may provide some benefit in these situations; however, little is known about whether these systems are effective in improving speech understanding in difficult acoustic environments for this population. This study was undertaken with adult cochlear implant recipients to assess the potential benefits of remote microphone technology. The objectives were to examine the measurable and perceived benefit of remote microphone devices during television viewing and to assess the benefits of a frequency-modulated system for speech understanding in noise. Fifteen adult unilateral cochlear implant users were fit with remote microphone devices in a clinical environment. The study used a combination of direct measurements and patient perceptions to assess speech understanding with and without remote microphone technology. The direct measures involved a within-subject repeated-measures design. Direct measures of patients' speech understanding during television viewing were collected using their cochlear implant alone and with their implant device coupled to an assistive listening device. Questionnaires were administered to document patients' perceptions of benefits during the television-listening tasks. Speech recognition tests of open-set sentences in noise with and without remote microphone technology were also administered. Participants showed improved speech understanding for television listening when using remote microphone devices coupled to their cochlear implant compared with a cochlear implant alone. This benefit was documented both when listening to news and talk show recordings. Questionnaire results also showed statistically significant differences between listening with a cochlear implant alone and listening with a remote microphone device. Participants judged that remote microphone technology provided them with better comprehension, more confidence, and greater ease of listening. Use of a frequency-modulated system coupled to a cochlear implant also showed significant improvement over a cochlear implant alone for open-set sentence recognition in +10 and +5 dB signal to noise ratios. Benefits were measured during remote microphone use in focused-listening situations in a clinical setting, for both television viewing and speech understanding in noise in the audiometric sound suite. The results suggest that adult cochlear implant users should be counseled regarding the potential for enhanced speech understanding in difficult listening environments through the use of remote microphone technology.

Melodic contour identification by cochlear implant listeners.

PubMed

Galvin, John J; Fu, Qian-Jie; Nogaki, Geraldine

2007-06-01

While the cochlear implant provides many deaf patients with good speech understanding in quiet, music perception and appreciation with the cochlear implant remains a major challenge for most cochlear implant users. The present study investigated whether a closed-set melodic contour identification (MCI) task could be used to quantify cochlear implant users' ability to recognize musical melodies and whether MCI performance could be improved with moderate auditory training. The present study also compared MCI performance with familiar melody identification (FMI) performance, with and without MCI training. For the MCI task, test stimuli were melodic contours composed of 5 notes of equal duration whose frequencies corresponded to musical intervals. The interval between successive notes in each contour was varied between 1 and 5 semitones; the "root note" of the contours was also varied (A3, A4, and A5). Nine distinct musical patterns were generated for each interval and root note condition, resulting in a total of 135 musical contours. The identification of these melodic contours was measured in 11 cochlear implant users. FMI was also evaluated in the same subjects; recognition of 12 familiar melodies was tested with and without rhythm cues. MCI was also trained in 6 subjects, using custom software and melodic contours presented in a different frequency range from that used for testing. Results showed that MCI recognition performance was highly variable among cochlear implant users, ranging from 14% to 91% correct. For most subjects, MCI performance improved as the number of semitones between successive notes was increased; performance was slightly lower for the A3 root note condition. Mean FMI performance was 58% correct when rhythm cues were preserved and 29% correct when rhythm cues were removed. Statistical analyses revealed no significant correlation between MCI performance and FMI performance (with or without rhythmic cues). However, MCI performance was significantly correlated with vowel recognition performance; FMI performance was not correlated with cochlear implant subjects' phoneme recognition performance. Preliminary results also showed that the MCI training improved all subjects' MCI performance; the improved MCI performance also generalized to improved FMI performance. Preliminary data indicate that the closed-set MCI task is a viable approach toward quantifying an important component of cochlear implant users' music perception. The improvement in MCI performance and generalization to FMI performance with training suggests that MCI training may be useful for improving cochlear implant users' music perception and appreciation; such training may be necessary to properly evaluate patient performance, as acute measures may underestimate the amount of musical information transmitted by the cochlear implant device and received by cochlear implant listeners.

Negotiating Reassurance: Parents' Narratives on Follow-Up after Cochlear Implantation

ERIC Educational Resources Information Center

Bruin, Marieke; Ohna, Stein Erik

2015-01-01

This study presents an analysis of parental experiences on follow-up after cochlear implantation. Data were constructed in semi-structured, individual interviews with the parents of 14 children who use cochlear implants. Drawing on narrative analysis, the study explores parental responses to insecurity concerning children's learning and…

Concept Learning and Heuristic Classification in Weak-Theory Domains

DTIC Science & Technology

1990-03-01

age and noise-induced cochlear age..gt.60 noise-induced cochlear air(mild) age-induced cochlear history(noise) norma ]_ear speechpoor)acousticneuroma...Annual review of computer science. Machine Learning, 4, 1990. (to appear). [18] R.T. Duran . Concept learning with incomplete data sets. Master’s thesis

Challenges in Optimizing Oral Communication in Children with Cochlear Implants.

ERIC Educational Resources Information Center

Ertmer, David J.

2002-01-01

This article introduces a forum that provides information for assisting speech-language pathologists and audiologists in fulfilling their professional responsibilities in a variety of settings to children with hearing impairments who have cochlear implants. A preview of the following articles on services for children with cochlear implants is…

Agile Development of Advanced Prototypes

DTIC Science & Technology

2014-11-01

prostheses: retinal implants, cochlear implants, and neuroprosthetics (EEG controlled artificial limbs); an interactive, virtual experience...demonstrations allowing users to experience, from a patient’s perspective life with three different prostheses: retinal implants, cochlear implants...three experiences were researched and developed. The applications are interactive demonstrations of retinal implants, cochlear implants, and

Voice emotion perception and production in cochlear implant users.

PubMed

Jiam, N T; Caldwell, M; Deroche, M L; Chatterjee, M; Limb, C J

2017-09-01

Voice emotion is a fundamental component of human social interaction and social development. Unfortunately, cochlear implant users are often forced to interface with highly degraded prosodic cues as a result of device constraints in extraction, processing, and transmission. As such, individuals with cochlear implants frequently demonstrate significant difficulty in recognizing voice emotions in comparison to their normal hearing counterparts. Cochlear implant-mediated perception and production of voice emotion is an important but relatively understudied area of research. However, a rich understanding of the voice emotion auditory processing offers opportunities to improve upon CI biomedical design and to develop training programs benefiting CI performance. In this review, we will address the issues, current literature, and future directions for improved voice emotion processing in cochlear implant users. Copyright © 2017 Elsevier B.V. All rights reserved.

Cochlear implantation for single-sided deafness and tinnitus suppression.

PubMed

Holder, Jourdan T; O'Connell, Brendan; Hedley-Williams, Andrea; Wanna, George

To quantify the potential effectiveness of cochlear implantation for tinnitus suppression in patients with single-sided deafness using the Tinnitus Handicap Inventory. The study included 12 patients with unilateral tinnitus who were undergoing cochlear implantation for single-sided deafness. The Tinnitus Handicap Inventory was administered at the patient's cochlear implant candidacy evaluation appointment prior to implantation and every cochlear implant follow-up appointment, except activation, following implantation. Patient demographics and speech recognition scores were also retrospectively recorded using the electronic medical record. A significant reduction was found when comparing Tinnitus Handicap Inventory score preoperatively (61.2±27.5) to the Tinnitus Handicap Inventory score after three months of cochlear implant use (24.6±28.2, p=0.004) and the Tinnitus Handicap Inventory score beyond 6months of CI use (13.3±18.9, p=0.008). Further, 45% of patients reported total tinnitus suppression. Mean CNC word recognition score improved from 2.9% (SD 9.4) pre-operatively to 40.8% (SD 31.7) by 6months post-activation, which was significantly improved from pre-operative scores (p=0.008). The present data is in agreement with previously published studies that have shown an improvement in tinnitus following cochlear implantation for the large majority of patients with single-sided deafness. Copyright © 2017 Elsevier Inc. All rights reserved.

Piribedil affects dopamine turnover in cochleas stimulated by white noise.

PubMed

Gil-Loyzaga, P; Vicente-Torres, M A; Fernández-Mateos, P; Arce, A; Esquifino, A

1994-09-01

The presence of dopamine (DA) within the cochlea has been previously reported, indicating that its turnover increases under noise stimulation. In the present report, piribedil, a dopaminergic D2 agonist, was used in order to provide evidence of the activity of D2 receptors in the turnover of DA under noise stimulation. Long-Evans rats were intraperitoneally injected with distilled water or with a solution of piribedil one hour previously to either noise or silence exposure. Noise stimulation was performed in an anechoic chamber at 70, 90 or 110 dB SPL for one hour. The animals were then sacrificed and the cochlear contents of DA and its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were quantified by HPLC with electrochemical detection. The administration of piribedil to animals kept in silence did not modify the cochlear DA, DOPAC and HVA content. Noise stimulation resulted in a decrease of the cochlear DA content and an increase of the cochlear DOPAC and HVA contents in vehicle treated animals. The administration of piribedil resulted in a blockade of this noise induced cochlear DA turnover. These results suggest that piribedil stimulates cochlear D2 receptors controlling the cochlear DA release. Piribedil action on D2 receptors could explain the improvement observed in some cochleo-vestibular diseases signs after piribedil treatment.

Considerations for Pediatric Cochlear Implant Recipients With Unilateral or Asymmetric Hearing Loss: Assessment, Device Fitting, and Habilitation.

PubMed

Greaver, Laura; Eskridge, Hannah; Teagle, Holly F B

2017-06-13

The purpose of this clinical report is to present case studies of children who are nontraditional candidates for cochlear implantation because they have significant residual hearing in 1 ear and to describe outcomes and considerations for their audiological management and habilitation. Case information is presented for 5 children with profound hearing loss in 1 ear and normal or mild-to-moderate hearing loss in the opposite ear and who have undergone unilateral cochlear implantation. Pre- and postoperative assessments were performed per typical clinic routines with modifications described. Postimplant habilitation was customized for each recipient using a combination of traditional methods, newer technologies, and commercial materials. The 5 children included in this report are consistent users of their cochlear implants and demonstrate speech recognition in the implanted ear when isolated from the better hearing ear. Candidacy criteria for cochlear implantation are evolving. Children with single-sided deafness or asymmetric hearing loss who have traditionally not been considered candidates for cochlear implantation should be evaluated on a case-by-case basis. Audiological management of these recipients is not vastly different compared with children who are traditional cochlear implant recipients. Assessment and habilitation techniques must be modified to isolate the implanted ear to obtain accurate results and to provide meaningful therapeutic intervention.

[Audiophonological evaluation of 16 children fitted with cochlear implants for sensorineural hearing loss induced by bacterial meningitis].

PubMed

Teissier, N; Doehring, I; Noel-Petroff, N; Elmaleh-Bergès, M; Viala, P; François, M; Faye, A; Van Den Abbeele, T; Lorrot, M

2013-06-01

Bacterial meningitis (BM) is the primary etiology of acquired sensorineural hearing loss (SNHL) in children and may compromise language development. Since the 1990 s, cochlear implants (CIs) have become part of the management of children with profound SNHL with encouraging results. The aim of this study was to analyze the audiophonological performance of children before and after cochlear implantation for SNHL following bacterial meningitis. Retrospective study of all children fitted with CIs for bilateral severe to profound SNHL after bacterial meningitis in the Robert-Debré pediatric ENT department between August 1990 and March 2009. Audiophonological performance was assessed using the APCEI profile. Of the 283 children receiving implants during that period, 16 children (6%; 6 boys, 10 girls) underwent CI implantation after bacterial meningitis (Streptococcus pneumoniae in 8 cases, Neisseria meningitidis in 2 cases, and Haemophilus influenzae in 4 cases). The mean time from meningitis to SNHL was 8.3 months (median, 1.5 months; range, 1 day to 13 years). The mean time from meningitis to cochlear implantation was 2 years and 3 months (median, 7 months; range, 1 month to 13 years 3 months). Twelve children (75%) presented partial cochlear and/or vestibular ossification on presurgical CT scan. Three children received bilateral implants. Thirteen children (81%) developed early SNHL in the first 3 months, whereas 3 children developed SNHL more than 10 months after meningitis. As for the benefits of cochlear implantation, 11 children presented near to normal intelligibility and optimal use of their cochlear implant; 5 children presented partial benefits due to neurological sequelae (1), a long delay before implantation (1), technical problems (2), or a social problem in relation to low socioeconomic status (1). After bacterial meningitis, audiological evaluation must be made carefully during the first 3 months to detect early SNHL, but SNHL may also develop several years later. In case of profound SNHL and a modified signal of the labyrinth on the MRI, cochlear implantation must be performed without delay before cochlear and/or vestibular ossification. Cochlear implantation is an effective technique with good long-term audiologic results. The coexistence of neurological lesions may compromise the results, but it should not contraindicate a cochlear implantation. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Modeling open-set spoken word recognition in postlingually deafened adults after cochlear implantation: some preliminary results with the neighborhood activation model.

PubMed

Meyer, Ted A; Frisch, Stefan A; Pisoni, David B; Miyamoto, Richard T; Svirsky, Mario A

2003-07-01

Do cochlear implants provide enough information to allow adult cochlear implant users to understand words in ways that are similar to listeners with acoustic hearing? Can we use a computational model to gain insight into the underlying mechanisms used by cochlear implant users to recognize spoken words? The Neighborhood Activation Model has been shown to be a reasonable model of word recognition for listeners with normal hearing. The Neighborhood Activation Model assumes that words are recognized in relation to other similar-sounding words in a listener's lexicon. The probability of correctly identifying a word is based on the phoneme perception probabilities from a listener's closed-set consonant and vowel confusion matrices modified by the relative frequency of occurrence of the target word compared with similar-sounding words (neighbors). Common words with few similar-sounding neighbors are more likely to be selected as responses than less common words with many similar-sounding neighbors. Recent studies have shown that several of the assumptions of the Neighborhood Activation Model also hold true for cochlear implant users. Closed-set consonant and vowel confusion matrices were obtained from 26 postlingually deafened adults who use cochlear implants. Confusion matrices were used to represent input errors to the Neighborhood Activation Model. Responses to the different stimuli were then generated by the Neighborhood Activation Model after incorporating the frequency of occurrence counts of the stimuli and their neighbors. Model outputs were compared with obtained performance measures on the Consonant-Vowel Nucleus-Consonant word test. Information transmission analysis was used to assess whether the Neighborhood Activation Model was able to successfully generate and predict word and individual phoneme recognition by cochlear implant users. The Neighborhood Activation Model predicted Consonant-Vowel Nucleus-Consonant test words at levels similar to those correctly identified by the cochlear implant users. The Neighborhood Activation Model also predicted phoneme feature information well. The results obtained suggest that the Neighborhood Activation Model provides a reasonable explanation of word recognition by postlingually deafened adults after cochlear implantation. It appears that multichannel cochlear implants give cochlear implant users access to their mental lexicons in a manner that is similar to listeners with acoustic hearing. The lexical properties of the test stimuli used to assess performance are important to spoken-word recognition and should be included in further models of the word recognition process.

Melodic Contour Identification and Music Perception by Cochlear Implant Users

PubMed Central

Galvin, John J.; Fu, Qian-Jie; Shannon, Robert V.

2013-01-01

Research and outcomes with cochlear implants (CIs) have revealed a dichotomy in the cues necessary for speech and music recognition. CI devices typically transmit 16–22 spectral channels, each modulated slowly in time. This coarse representation provides enough information to support speech understanding in quiet and rhythmic perception in music, but not enough to support speech understanding in noise or melody recognition. Melody recognition requires some capacity for complex pitch perception, which in turn depends strongly on access to spectral fine structure cues. Thus, temporal envelope cues are adequate for speech perception under optimal listening conditions, while spectral fine structure cues are needed for music perception. In this paper, we present recent experiments that directly measure CI users’ melodic pitch perception using a melodic contour identification (MCI) task. While normal-hearing (NH) listeners’ performance was consistently high across experiments, MCI performance was highly variable across CI users. CI users’ MCI performance was significantly affected by instrument timbre, as well as by the presence of a competing instrument. In general, CI users had great difficulty extracting melodic pitch from complex stimuli. However, musically-experienced CI users often performed as well as NH listeners, and MCI training in less experienced subjects greatly improved performance. With fixed constraints on spectral resolution, such as it occurs with hearing loss or an auditory prosthesis, training and experience can provide a considerable improvements in music perception and appreciation. PMID:19673835

Using Temporal Modulation Sensitivity to Select Stimulation Sites for Processor MAPs in Cochlear Implant Listeners

PubMed Central

Garadat, Soha N.; Zwolan, Teresa A.; Pfingst, Bryan E.

2013-01-01

Previous studies in our laboratory showed that temporal acuity as assessed by modulation detection thresholds (MDTs) varied across activation sites and that this site-to-site variability was subject specific. Using two 10-channel MAPs, the previous experiments showed that processor MAPs that had better across-site mean (ASM) MDTs yielded better speech recognition than MAPs with poorer ASM MDTs tested in the same subject. The current study extends our earlier work on developing more optimal fitting strategies to test the feasibility of using a site-selection approach in the clinical domain. This study examined the hypothesis that revising the clinical speech processor MAP for cochlear implant (CI) recipients by turning off selected sites that have poorer temporal acuity and reallocating frequencies to the remaining electrodes would lead to improved speech recognition. Twelve CI recipients participated in the experiments. We found that site selection procedure based on MDTs in the presence of a masker resulted in improved performance on consonant recognition and recognition of sentences in noise. In contrast, vowel recognition was poorer with the experimental MAP than with the clinical MAP, possibly due to reduced spectral resolution when sites were removed from the experimental MAP. Overall, these results suggest a promising path for improving recipient outcomes using personalized processor-fitting strategies based on a psychophysical measure of temporal acuity. PMID:23881208

Macrophage recruitment, but not interleukin 1 beta activation, enhances noise-induced hearing damage.

PubMed

Mizushima, Yu; Fujimoto, Chisato; Kashio, Akinori; Kondo, Kenji; Yamasoba, Tatsuya

2017-11-18

It has been suggested that macrophages or inflammatory monocytes participate in the pathology of noise-induced hearing loss (NIHL), but it is unclear how extensively these cells contribute to the development of temporary and/or permanent NIHL. To address this question, we used clodronate liposomes to deplete macrophages and monocytes. After clodronate liposome injection, mice were exposed to 4-kHz octave band noise at 121 dB for 4 h. Compared to vehicle-injected controls, clodronate-treated mice exhibited significantly reduced permanent threshold shifts at 4 and 8 kHz and significantly smaller outer hair cell losses in the lower-apical cochlear turn. Following noise exposure, the stria vascularis had significantly more cells expressing the macrophage-specific protein F4/80, and this effect was significantly suppressed by clodronate treatment. These F4/80-positive cells expressed interleukin 1 beta (IL-1β), which noise exposure activated. However, IL-1β deficient mice did not exhibit significant resistance to intense noise when compared to wild-type mice. These findings suggest that macrophages that enter the cochlea after noise exposure are involved in NIHL, whereas IL-1β inhibition does not reverse this cochlear damage. Therefore, macrophages may be a promising therapeutic target in human sensorineural hearing losses such as NIHL. Copyright © 2017 Elsevier Inc. All rights reserved.

High-Frequency Vibration of the Organ of Corti in Vitro

NASA Astrophysics Data System (ADS)

Scherer, M. P.; Nowotny, M.; Dalhoff, E.; Zenner, H.-P.; Gummer, A. W.

2003-02-01

The mechanism by which the electromechanical force generated by the outer hair cells (OHC) produces the exquisite sensitivity, frequency selectivity and dynamic range of the cochlea is unknown. To address this question, we measured the electrically induced radial vibration pattern at different levels within the organ of Corti of the guinea pig. Two in vitro preparations were used: 1) a half turn including modiolar bone and cochlear partition, without tectorial membrane (TM); the basilar membrane (BM) was supported from its tympanal side. 2) A temporal bone preparation, where the bony wall was removed above and below the measurement location to permit introduction of electrodes. In the latter case, the cochlear partition was in its normal mechanical environment, with free swinging BM and with TM. Velocity of BM, reticular lamina (RL), and upper and lower sides of the TM in response to broadband electrical stimulation of the OHCs was measured with a laser Doppler vibrometer. The interferometer was sensitive enough to permit measurement without reflective beads or the like. The frequency range of the stimulation was 480 Hz - 70 kHz. Displacement amplitudes were constant up to 10 kHz, after which they dropped with -14 to -17 dB/oct. Moving across the RL in the radial direction, phase reversals characteristic of pivoting points occurred above the pillar cells and the outer tunnel. No phase reversals were observed on the BM and TM.

Recognition and Localization of Speech by Adult Cochlear Implant Recipients Wearing a Digital Hearing Aid in the Nonimplanted Ear (Bimodal Hearing)

PubMed Central

Potts, Lisa G.; Skinner, Margaret W.; Litovsky, Ruth A.; Strube, Michael J; Kuk, Francis

2010-01-01

Background The use of bilateral amplification is now common clinical practice for hearing aid users but not for cochlear implant recipients. In the past, most cochlear implant recipients were implanted in one ear and wore only a monaural cochlear implant processor. There has been recent interest in benefits arising from bilateral stimulation that may be present for cochlear implant recipients. One option for bilateral stimulation is the use of a cochlear implant in one ear and a hearing aid in the opposite nonimplanted ear (bimodal hearing). Purpose This study evaluated the effect of wearing a cochlear implant in one ear and a digital hearing aid in the opposite ear on speech recognition and localization. Research Design A repeated-measures correlational study was completed. Study Sample Nineteen adult Cochlear Nucleus 24 implant recipients participated in the study. Intervention The participants were fit with a Widex Senso Vita 38 hearing aid to achieve maximum audibility and comfort within their dynamic range. Data Collection and Analysis Soundfield thresholds, loudness growth, speech recognition, localization, and subjective questionnaires were obtained six–eight weeks after the hearing aid fitting. Testing was completed in three conditions: hearing aid only, cochlear implant only, and cochlear implant and hearing aid (bimodal). All tests were repeated four weeks after the first test session. Repeated-measures analysis of variance was used to analyze the data. Significant effects were further examined using pairwise comparison of means or in the case of continuous moderators, regression analyses. The speech-recognition and localization tasks were unique, in that a speech stimulus presented from a variety of roaming azimuths (140 degree loudspeaker array) was used. Results Performance in the bimodal condition was significantly better for speech recognition and localization compared to the cochlear implant–only and hearing aid–only conditions. Performance was also different between these conditions when the location (i.e., side of the loudspeaker array that presented the word) was analyzed. In the bimodal condition, the speech-recognition and localization tasks were equal regardless of which side of the loudspeaker array presented the word, while performance was significantly poorer for the monaural conditions (hearing aid only and cochlear implant only) when the words were presented on the side with no stimulation. Binaural loudness summation of 1–3 dB was seen in soundfield thresholds and loudness growth in the bimodal condition. Measures of the audibility of sound with the hearing aid, including unaided thresholds, soundfield thresholds, and the Speech Intelligibility Index, were significant moderators of speech recognition and localization. Based on the questionnaire responses, participants showed a strong preference for bimodal stimulation. Conclusions These findings suggest that a well-fit digital hearing aid worn in conjunction with a cochlear implant is beneficial to speech recognition and localization. The dynamic test procedures used in this study illustrate the importance of bilateral hearing for locating, identifying, and switching attention between multiple speakers. It is recommended that unilateral cochlear implant recipients, with measurable unaided hearing thresholds, be fit with a hearing aid. PMID:19594084

Intraoperative cochlear nerve mapping with the mobile cochlear nerve compound action potential tracer in vestibular schwannoma surgery.

PubMed

Watanabe, Nobuyuki; Ishii, Takuya; Fujitsu, Kazuhiko; Kaku, Shogo; Ichikawa, Teruo; Miyahara, Kosuke; Okada, Tomu; Tanino, Shin; Uriu, Yasuhiro; Murayama, Yuichi

2018-05-18

OBJECTIVE The authors describe the usefulness and limitations of the cochlear nerve compound action potential (CNAP) mobile tracer (MCT) that they developed to aid in cochlear nerve mapping during vestibular schwannoma surgery (VSS) for hearing preservation. METHODS This MCT device requires no more than 2 seconds for stable placement on the nerve to obtain the CNAP and thus is able to trace the cochlear nerve instantaneously. Simultaneous bipolar and monopolar recording is possible. The authors present the outcomes of 18 consecutive patients who underwent preoperative useful hearing (defined as class I or II of the Gardner-Robertson classification system) and underwent hearing-preservation VSS with the use of the MCT. Mapping was considered successful when it was possible to detect and trace the cochlear nerve. RESULTS Mapping of the cochlear nerve was successful in 13 of 18 patients (72.2%), and useful hearing was preserved in 11 patients (61.1%). Among 8 patients with large tumors (Koos grade 3 or 4), the rate of successful mapping was 62.5% (5 patients). The rate of hearing preservation in patients with large tumors was 50% (4 patients). CONCLUSIONS In addition to microsurgical presumption of the arrangement of each nerve, frequent probing on and around an unidentified nerve and comparison of each waveform are advisable with the use of both more sensitive monopolar and more location-specific bipolar MCT. MCT proved to be useful in cochlear nerve mapping and may consequently be helpful in hearing preservation. The authors discuss some limitations and problems with this device.

Timing Discrepancies of Early Intervention Hearing Services in Urban and Rural Cochlear Implant Recipients

PubMed Central

Bush, Matthew L.; Burton, Mary; Loan, Ashley; Shinn, Jennifer B.

2013-01-01

Objective The purpose of this study was to examine the timing of early intervention diagnostic and therapeutic services in cochlear implant recipients from rural and urban areas. Study design Retrospective case series review Setting Tertiary referral center Patients Cochlear implant recipients from a single comprehensive hearing institute born with severe congenital sensorineural hearing loss were examined. Timing of diagnostic and therapeutic services was examined. Intervention(s) Diagnosis, amplification, and eventual cochlear implantation for all patients in the study Main outcome measure(s) Time points of definitive diagnosis, amplification, and cochlear implantation for children from urban and rural regions were examined. Correlation analysis of distance to testing center and timing of services was also assessed. Results 40 children born with congenital hearing loss were included in the study and were diagnosed at a median age of 13 weeks after birth. Children from rural regions obtained amplification at a median age of 47.7 weeks after birth, while urban children were amplified at 26 weeks after birth. Cochlear implantation was performed at a median age of 182 weeks after birth in those from rural areas and at 104 weeks after birth in urban-dwelling patients. A linear relationship was identified between distance to the implant center and timing of hearing aid amplification (r=0.5, p=0.033) and cochlear implantation (r=0.5, p=0.016). Conclusions Children residing outside of metro areas may be at higher risk of delayed rehabilitative services and cochlear implantation than those residing in urban areas that may be closer in proximity to tertiary care centers. PMID:24136305

The cochlear CRF signaling systems and their mechanisms of action in modulating cochlear sensitivity and protection against trauma

PubMed Central

Graham, Christine E.; Basappa, Johnvesly; Turcan, Sevin; Vetter, Douglas E.

2011-01-01

A key requirement for encoding the auditory environment is the ability to dynamically alter cochlear sensitivity. However, merely attaining a steady state of maximal sensitivity is not a viable solution since the sensory cells and ganglion cells of the cochlea are prone to damage following exposure to loud sound. Most often, such damage is via initial metabolic insult that can lead to cellular death. Thus, establishing the highest sensitivity must be balanced with protection against cellular metabolic damage that can lead to loss of hair cells and ganglion cells, resulting in loss of frequency representation. While feedback mechanisms are known to exist in the cochlea that alter sensitivity, they respond only after stimulus encoding, allowing potentially damaging sounds to impact the inner ear at times coincident with increased sensitivity. Thus, questions remain concerning the endogenous signaling systems involved in dynamic modulation of cochlear sensitivity and protection against metabolic stress. Understanding endogenous signaling systems involved in cochlear protection may lead to new strategies and therapies for prevention of cochlear damage and consequent hearing loss. We have recently discovered a novel cochlear signaling system that is molecularly equivalent to the classic hypothalamic-pituitary-adrenal (HPA) axis. This cochlear HPA-equivalent system functions to balance auditory sensitivity and susceptibility to noise-induced hearing loss, and also protects against cellular metabolic insults resulting from exposures to ototoxic drugs. We review the anatomy, physiology, and cellular signaling of this system, and compare it to similar signaling in other organs/tissues of the body. PMID:21909974

Preventing hearing damage using topical dexamethasone during reversible cochlear ischemia: an animal model.

PubMed

Morawski, Krzysztof; Telischi, Fred F; Bohorquez, Jorge; Niemczyk, Kazimierz

2009-09-01

Local application of dexamethasone to the round window (RW) niche prevents cochlear damage caused by local reversible ischemia. Cochlear ischemia induced by internal auditory artery (IAA) compression/stretching is thought to cause postoperative sensory hearing loss after attempted hearing preservation removal of acoustic neuroma tumors. Dexamethasone administered to the RW niche traveling through the membrane to the cochlear fluids may prevent ischemic damage. Ten young albino rabbits were used for this study. Ischemic episodes were induced by compressing the IAA. Laser Doppler cochlear blood flow was measured using a probe positioned at the RW niche. Transtympanic electrocochleography was measured at 4, 8, and 12 kHz. In 5 test ears, dexamethasone was administered topically at the RW for approximately 50 minutes before the IAA compressions, whereas in 5 control ears, saline was applied in the same way. Each ear underwent one 10-minute IAA compression with a 60-minute postischemic period of transtympanic electrocochleography monitoring. In both control- and dexamethasone-treated ears, ischemic episodes measured by Laser Doppler cochlear blood flow were comparable. Fifty minutes after IAA decompression, in dexamethasone-pretreated ears, cochlear microphonic and compound action potential amplitudes at all test frequencies were 10 to 15% less reduced than those in control ears. Compound action potential latencies in dexamethasone-pretreated ears resulted in shorter latency delay than in control ears. The RW seems to be an efficacious route for the administration of dexamethasone into the inner ear. Dexamethasone showed a protective effect on cochlear function after local ischemia. Transtympanic electrocochleography was found to be a sufficient and effective tool in monitoring hearing.

Quality-of-life benefit from cochlear implantation in the elderly.

PubMed

Vermeire, Katrien; Brokx, Jan P L; Wuyts, Floris L; Cochet, Ellen; Hofkens, Anouk; Van de Heyning, Paul H

2005-03-01

To compare the audiologic results of geriatric patients receiving cochlear implants with younger age groups and to evaluate the quality of life after cochlear implantation in the geriatric population by means of validated quality-of-life questionnaires. Cross-sectional study involving 89 postlingually deafened cochlear implant subjects. Tertiary referral center. A total of 89 postlingually deafened patients were included in the study, among which were 25 patients who were aged 70 years or older. All patients received a cochlear implant. Subjects were implanted with either the Laura, Nucleus 24, or Med-el Combi 40+ cochlear implant systems implementing the SPEAK, ACE, CIS, or CIS+ coding strategies. Speech recognition was determined by means of phonetically balanced monosyllabic word lists. The Hearing Handicap Inventory for Adults, the Glasgow Benefit Inventory, and the scale for the prediction of hearing disability in sensorineural hearing loss were used to quantify the quality of life. Mean audiologic performance for the three groups increased significantly after implantation (p < 0.001). Postoperative audiologic performance of the geriatric population led to useful hearing, but these scores were significantly lower than for the younger age groups (p = 0.002). However, the quality-of-life outcomes for the geriatric group were similar to those of the younger age groups (p = 0.411 for the Hearing Handicap Inventory for Adults; p = 0.886 for the Glasgow Benefit Inventory). The results of this study prove that cochlear implantation in the elderly provides improvements in quality of life and speech understanding, similar to those for younger adult cochlear implant recipients.

EEG frontal asymmetry related to pleasantness of music perception in healthy children and cochlear implanted users.

PubMed

Vecchiato, G; Maglione, A G; Scorpecci, A; Malerba, P; Marsella, P; Di Francesco, G; Vitiello, S; Colosimo, A; Babiloni, Fabio

2012-01-01

Interestingly, the international debate about the quality of music fruition for cochlear implanted users does not take into account the hypothesis that bilateral users could perceive music in a more pleasant way with respect to monolateral users. In this scenario, the aim of the present study was to investigate if cerebral signs of pleasantness during music perception in healthy child are similar to those observed in monolateral and in bilateral cochlear implanted users. In fact, previous observations in literature on healthy subjects have indicated that variations of the frontal EEG alpha activity are correlated with the perceived pleasantness of the sensory stimulation received (approach-withdrawal theory). In particular, here we described differences between cortical activities estimated in the alpha frequency band for a healthy child and in patients having a monolateral or a bilateral cochlear implant during the fruition of a musical cartoon. The results of the present analysis showed that the alpha EEG asymmetry patterns observed in a healthy child and that of a bilateral cochlear implanted patient are congruent with the approach-withdrawal theory. Conversely, the scalp topographic distribution of EEG power spectra in the alpha band resulting from the monolateral cochlear user presents a different EEG pattern from the normal and bilateral implanted patients. Such differences could be explained at the light of the approach-withdrawal theory. In fact, the present findings support the hypothesis that a monolateral cochlear implanted user could perceive the music in a less pleasant way when compared to a healthy subject or to a bilateral cochlear user.

Educational, employment, and social participation of young adult graduates from the paediatric Southern Cochlear Implant Programme, New Zealand.

PubMed

Goh, Terence; Bird, Philip; Pearson, John; Mustard, Jill

2016-01-01

The purpose of this study is to observe the education and vocational achievements and social participation of cochlear implant recipients as they graduate from a paediatric cochlear implant programme and identify any significant associations that might exist. This study identified 56 patients from the Southern Cochlear Implant Programme (SCIP) who received cochlear implants before the age of 19 (paediatric) and are now over the age of 19 (adult). A questionnaire investigated their education, employment, and identity with the hearing and deaf communities. Also included were the satisfaction with life scale and Hearing Participation Scale (HPS). Subjects ranged in age from 19 to 32. Twenty-six patients responded to the questionnaire, including one non-user. Twenty identified strongly or very strongly with the hearing community. There was weak evidence of a linear association between strong identity with the hearing community and a higher HPS score. No other statistically significant associations were detected. Interestingly, 12 out of 26 participants found employment through family. Positive outcome trends in education and employment were seen in this study although no statistical significance was achieved. There is a strong bias for those who use their cochlear implants regularly, and there are no data available for those who do not use their cochlear implants for comparison as only one non-user completed the survey, despite efforts to include this group. This study shows that there is perceived benefit in implantation for patients who use it regularly but further research is needed with a more diverse group of cochlear implant recipients.

Pediatric Cochlear Implants: An Overview of the Alternatives in Education and Rehabilitation.

ERIC Educational Resources Information Center

Barnes, Judith M., Ed.; And Others

This collection of 10 papers is intended as a resource book integrating information on pediatric cochlear implants for educators, parents, implant teams, and rehabilitation specialists. The papers focus on the importance of providing an oral educational environment to maximize cochlear implant success. An introduction notes controversies in the…

Realization of Complex Onsets by Pediatric Users of Cochlear Implants

ERIC Educational Resources Information Center

Chin, Steven B.

2006-01-01

This study examined variations in English complex onset realizations by children who use cochlear implants. Data consisted of 227 productions of two-segment onset clusters from 12 children. In general, onset cluster realizations of children with cochlear implants did not differ markedly from those reported for children with normal hearing: null…

Contribution of Family Environment to Pediatric Cochlear Implant Users' Speech and Language Outcomes: Some Preliminary Findings

ERIC Educational Resources Information Center

Holt, Rachael Frush; Beer, Jessica; Kronenberger, William G.; Pisoni, David B.; Lalonde, Kaylah

2012-01-01

Purpose: To evaluate the family environments of children with cochlear implants and to examine relationships between family environment and postimplant language development and executive function. Method: Forty-five families of children with cochlear implants completed a self-report family environment questionnaire (Family Environment Scale-Fourth…

Taxonomic Knowledge of Children with and without Cochlear Implants

ERIC Educational Resources Information Center

Lund, Emily; Dinsmoor, Jessica

2016-01-01

Purpose: The purpose of this study was to compare the taxonomic vocabulary knowledge and organization of children with cochlear implants to (a) children with normal hearing matched for age, and (b) children matched for vocabulary development. Method: Ten children with cochlear implants, 10 age-matched children with normal hearing, and 10…

Children with Cochlear Implants in Australia: Educational Settings, Supports, and Outcomes

ERIC Educational Resources Information Center

Punch, Renee; Hyde, Merv

2010-01-01

This Australian study examined the communication, academic, and social outcomes of pediatric cochlear implantation from the perspectives of teachers working with children with cochlear implants. The children were aged from 1 to 18 years and attended a range of educational settings in early intervention, primary, and secondary schooling. One…

Cochlear Implants in Children with Hearing Loss: Maternal Expectations and Impact on the Family

ERIC Educational Resources Information Center

Zaidman-Zait, Anat; Most, Tova

2005-01-01

To facilitate evaluations of cochlear implant candidates and to promote (re)habilitation efficacy and collaboration with families, this study examined the expectations of 35 mothers with typical hearing and their beliefs and difficulties related to their child's hearing loss and current or future cochlear implantation. Questionnaires measured…

Persistent Language Delay versus Late Language Emergence in Children with Early Cochlear Implantation

ERIC Educational Resources Information Center

Geers, Ann E.; Nicholas, Johanna; Tobey, Emily; Davidson, Lisa

2016-01-01

Purpose: The purpose of the present investigation is to differentiate children using cochlear implants (CIs) who did or did not achieve age-appropriate language scores by mid-elementary grades and to identify risk factors for persistent language delay following early cochlear implantation. Materials and Method: Children receiving unilateral CIs at…

Serving Deaf Students Who Have Cochlear Implants. PEPNet Tipsheet

ERIC Educational Resources Information Center

Searls, J. Matt, Comp.

2010-01-01

Cochlear implants (CIs) are complex electronic devices surgically implanted under the skin behind the ear. These devices utilize electrodes placed in the inner ear (the cochlea) to stimulate the auditory nerve of individuals with significant permanent hearing loss. Cochlear implants may not be suitable for everyone. They are designed to provide…

Verbal Working Memory in Children with Cochlear Implants

ERIC Educational Resources Information Center

Nittrouer, Susan; Caldwell-Tarr, Amanda; Low, Keri E.; Lowenstein, Joanna H.

2017-01-01

Purpose: Verbal working memory in children with cochlear implants and children with normal hearing was examined. Participants: Ninety-three fourth graders (47 with normal hearing, 46 with cochlear implants) participated, all of whom were in a longitudinal study and had working memory assessed 2 years earlier. Method: A dual-component model of…

Emotion Understanding in Deaf Children with a Cochlear Implant

ERIC Educational Resources Information Center

Wiefferink, Carin H.; Rieffe, Carolien; Ketelaar, Lizet; De Raeve, Leo; Frijns, Johan H. M.

2013-01-01

It is still largely unknown how receiving a cochlear implant affects the emotion understanding in deaf children. We examined indices for emotion understanding and their associations with communication skills in children aged 2.5-5 years, both hearing children (n = 52) and deaf children with a cochlear implant (n = 57). 2 aspects of emotion…

Evaluating the Feasibility of Using Remote Technology for Cochlear Implants

ERIC Educational Resources Information Center

Goehring, Jenny L.; Hughes, Michelle L.; Baudhuin, Jacquelyn L.

2012-01-01

The use of remote technology to provide cochlear implant services has gained popularity in recent years. This article contains a review of research evaluating the feasibility of remote service delivery for recipients of cochlear implants. To date, published studies have determined that speech-processor programming levels and other objective tests…

Scala tympani cochleostomy I: results of a survey.

PubMed

Adunka, Oliver F; Buchman, Craig A

2007-12-01

To assess current surgical techniques for scala tympani cochlear implantation among North American surgeons. A survey was distributed to all cochlear implant surgeons participating in the 2006 William House Cochlear Implant Study Group in Toronto, Canada. Participants were asked to anonymously identify their routine surgical practices. Images of trans-facial recess approaches to the round window and cochlear promontory were used in a multiple-choice fashion to assess the surgeon's typical exposure and cochleostomy location. Returned questionnaires were electronically processed and evaluated. Fifty-five (75%) of 73 returned surveys had adequate data validity and availability. Landmark identification and preferred cochleostomy locations varied greatly. About 20% of surgeons selected cochleostomy locations superior to the round window membrane. Cochleostomy size and location appeared to be influenced by surgical experience and whether or not the round window overhang was drilled off. This survey clearly documents marked variations in surgical techniques for scala tympani cochlear implantation. Future studies should more clearly define the surgical anatomy of this region for appropriate placement of a scala tympani cochleostomy. These findings may ultimately have an impact on hearing and neural preservation cochlear implant surgeries.

Comparison of intelligence quotients of first- and second-generation deaf children with cochlear implants.

PubMed

Amraei, K; Amirsalari, S; Ajalloueyan, M

2017-01-01

Hearing impairment is a common type of sensory loss in children. Studies indicate that children with hearing impairment are deficient in social, cognitive and communication skills. This study compared the intelligence quotients of first- and second-generation deaf children with cochlear implants. This research is causal-comparative. All 15 deaf children investigated had deaf parents and were selected from Baqiyatallah Cochlear Implant Center. The 15 children with cochlear implants were paired with similar children with hearing parents using purposive sampling. The findings show that the Hotelling trace of multivariate analysis of variance (F = 6.78, p < 0.01, η P 2  = 0.73) was significant. The tests of between-subjects effects for second-generation children was significantly higher than for first-generation children for all intelligence scales except knowledge. It can be assumed that second-generation children joined their family in the use of sign language as the primary experience before a cochlear implant. The use of sign language before cochlear implants is recommended. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Cochlear Implants and Psychiatric Assessments: a Norrie Disease Case Report.

PubMed

Jacques, Denis; Dubois, Thomas; Zdanowicz, Nicolas; Gilain, Chantal; Garin, Pierre

2017-09-01

It is important to perform psychiatric assessments of adult patients who are candidates for cochlear implants both to screen them for psychiatric disorders and to assess their understanding and compliance with the procedure. Deafness is a factor of difficulty for conducting in-depth psychiatric interviews, but concomitant blindness may make it impossible. After a description of Norrie disease, a rare disease in which blindness and deafness may occur together, we propose a case report of a patient suffering from the disease and who consulted in view of a cochlear implant. Early information on cochlear implants appears to be necessary before total deafness occurs in patients suffering from Norrie disease. An inventory of digital communication tools that can be used by the patient is also highly valuable. Research should be supported for a more systematic use of psychiatric assessments prior to cochlear implants. In the special case of Norrie disease, we recommend early screening for mental retardation and related psychotic disorders and, depending on the patient's level of understanding, preventive information on the benefits and limits of cochlear implants before total deafness occurs.

Evaluation of a cochlear-implant processing strategy incorporating phantom stimulation and asymmetric pulses

PubMed Central

Monstrey, Jolijn; Deeks, John M.; Macherey, Olivier

2014-01-01

Objective To evaluate a speech-processing strategy in which the lowest frequency channel is conveyed using an asymmetric pulse shape and “phantom stimulation”, where current is injected into one intra-cochlear electrode and where the return current is shared between an intra-cochlear and an extra-cochlear electrode. This strategy is expected to provide more selective excitation of the cochlear apex, compared to a standard strategy where the lowest-frequency channel is conveyed by symmetric pulses in monopolar mode. In both strategies all other channels were conveyed by monopolar stimulation. Design Within-subjects comparison between the two strategies. Four experiments: (1) discrimination between the strategies, controlling for loudness differences, (2) consonant identification, (3) recognition of lowpass-filtered sentences in quiet, (4) sentence recognition in the presence of a competing speaker. Study sample Eight users of the Advanced Bionics CII/Hi-Res 90k cochlear implant. Results Listeners could easily discriminate between the two strategies but no consistent differences in performance were observed. Conclusions The proposed method does not improve speech perception, at least in the short term. PMID:25358027

Evaluation of a cochlear-implant processing strategy incorporating phantom stimulation and asymmetric pulses.

PubMed

Carlyon, Robert P; Monstrey, Jolijn; Deeks, John M; Macherey, Olivier

2014-12-01

To evaluate a speech-processing strategy in which the lowest frequency channel is conveyed using an asymmetric pulse shape and "phantom stimulation", where current is injected into one intra-cochlear electrode and where the return current is shared between an intra-cochlear and an extra-cochlear electrode. This strategy is expected to provide more selective excitation of the cochlear apex, compared to a standard strategy where the lowest-frequency channel is conveyed by symmetric pulses in monopolar mode. In both strategies all other channels were conveyed by monopolar stimulation. Within-subjects comparison between the two strategies. Four experiments: (1) discrimination between the strategies, controlling for loudness differences, (2) consonant identification, (3) recognition of lowpass-filtered sentences in quiet, (4) sentence recognition in the presence of a competing speaker. Eight users of the Advanced Bionics CII/Hi-Res 90k cochlear implant. Listeners could easily discriminate between the two strategies but no consistent differences in performance were observed. The proposed method does not improve speech perception, at least in the short term.

Dissociating hippocampal and basal ganglia contributions to category learning using stimulus novelty and subjective judgments

PubMed Central

Seger, Carol A.; Dennison, Christina S.; Lopez-Paniagua, Dan; Peterson, Erik J.; Roark, Aubrey A.

2011-01-01

We identified factors leading to hippocampal and basal ganglia recruitment during categorization learning. Subjects alternated between blocks of a standard trial and error category learning task and a subjective judgment task. In the subjective judgments task subjects categorized the stimulus and then instead of receiving feedback they indicated the basis of their response using 4 options: Remember: Conscious episodic memory of previous trials. Know-Automatic: Automatic, rapid response accompanied by conscious awareness of category membership. Know-Intuition: A “gut feeling” without fully conscious knowledge of category membership. Guess: Guessing. In addition, new stimuli were introduced throughout the experiment to examine effects of novelty. Categorization overall recruited both the basal ganglia and posterior hippocampus. However, basal ganglia activity was found during Know judgments (both Automatic and Intuition), whereas posterior hippocampus activity was found during Remember judgments. Granger causality mapping indicated interactions between the basal ganglia and hippocampus, with the putamen exerting directed influence on the posterior hippocampus, which in turn exerted directed influence on the posterior caudate nucleus. We also found a region of anterior hippocampus that showed decreased activity relative to baseline during categorization overall, and showed a strong novelty effect. Our results indicate that subjective measures may be effective in dissociating basal ganglia from hippocampal dependent learning, and that the basal ganglia are involved in both conscious and unconscious learning. They also indicate a dissociation within the hippocampus, in which the anterior regions are sensitive to novelty, and the posterior regions are involved in memory based categorization learning. PMID:21255655

Bringing Hearing to the Deaf

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shipsey, Ian

In his talk, Shipsey will discuss the cochlear implant, the first device to successfully allow the profoundly deaf to regain some sense of hearing. A cochlear implant is a small electronic apparatus. Unlike a normal hearing aid, which amplifies sound, a cochlear implant is surgically implanted behind the ear where it converts sound waves into electrical impulses. These implants have instigated a popular but controversial revolution in the treatment of deafness, and they serve as a model for research in neuroscience and biomedical engineering. Shipsey will discuss the physiology of natural hearing from the perspective of a physicist. He willmore » also touch on the function of cochlear implants in the context of historical treatments, electrical engineering, psychophysics, clinical evaluation of efficacy and personal experience. Finally, Shipsey will address the social implications of cochlear implantation and the future outlook for auditory prostheses.« less

Effect of age at cochlear implantation on auditory and speech development of children with auditory neuropathy spectrum disorder.

PubMed

Liu, Yuying; Dong, Ruijuan; Li, Yuling; Xu, Tianqiu; Li, Yongxin; Chen, Xueqing; Gong, Shusheng

2014-12-01

To evaluate the auditory and speech abilities in children with auditory neuropathy spectrum disorder (ANSD) after cochlear implantation (CI) and determine the role of age at implantation. Ten children participated in this retrospective case series study. All children had evidence of ANSD. All subjects had no cochlear nerve deficiency on magnetic resonance imaging and had used the cochlear implants for a period of 12-84 months. We divided our children into two groups: children who underwent implantation before 24 months of age and children who underwent implantation after 24 months of age. Their auditory and speech abilities were evaluated using the following: behavioral audiometry, the Categories of Auditory Performance (CAP), the Meaningful Auditory Integration Scale (MAIS), the Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS), the Standard-Chinese version of the Monosyllabic Lexical Neighborhood Test (LNT), the Multisyllabic Lexical Neighborhood Test (MLNT), the Speech Intelligibility Rating (SIR) and the Meaningful Use of Speech Scale (MUSS). All children showed progress in their auditory and language abilities. The 4-frequency average hearing level (HL) (500Hz, 1000Hz, 2000Hz and 4000Hz) of aided hearing thresholds ranged from 17.5 to 57.5dB HL. All children developed time-related auditory perception and speech skills. Scores of children with ANSD who received cochlear implants before 24 months tended to be better than those of children who received cochlear implants after 24 months. Seven children completed the Mandarin Lexical Neighborhood Test. Approximately half of the children showed improved open-set speech recognition. Cochlear implantation is helpful for children with ANSD and may be a good optional treatment for many ANSD children. In addition, children with ANSD fitted with cochlear implants before 24 months tended to acquire auditory and speech skills better than children fitted with cochlear implants after 24 months. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Tinnitus after Simultaneous and Sequential Bilateral Cochlear Implantation.

PubMed

Ramakers, Geerte G J; Kraaijenga, Véronique J C; Smulders, Yvette E; van Zon, Alice; Stegeman, Inge; Stokroos, Robert J; Free, Rolien H; Frijns, Johan H M; Huinck, Wendy J; Van Zanten, Gijsbert A; Grolman, Wilko

2017-01-01

There is an ongoing global discussion on whether or not bilateral cochlear implantation should be standard care for bilateral deafness. Contrary to unilateral cochlear implantation, however, little is known about the effect of bilateral cochlear implantation on tinnitus. To investigate tinnitus outcomes 1 year after bilateral cochlear implantation. Secondarily, to compare tinnitus outcomes between simultaneous and sequential bilateral cochlear implantation and to investigate long-term follow-up (3 years). This study is a secondary analysis as part of a multicenter randomized controlled trial. Thirty-eight postlingually deafened adults were included in the original trial, in which the presence of tinnitus was not an inclusion criterion. All participants received cochlear implants (CIs) because of profound hearing loss. Nineteen participants received bilateral CIs simultaneously and 19 participants received bilateral CIs sequentially with an inter-implant interval of 2 years. The prevalence and severity of tinnitus before and after simultaneous and sequential bilateral cochlear implantation were measured preoperatively and each year after implantation with the Tinnitus Handicap Inventory (THI) and Tinnitus Questionnaire (TQ). The prevalence of preoperative tinnitus was 42% (16/38). One year after bilateral implantation, there was a median difference of -8 (inter-quartile range (IQR): -28 to 4) in THI score and -9 (IQR: -17 to -9) in TQ score in the participants with preoperative tinnitus. Induction of tinnitus occurred in five participants, all in the simultaneous group, in the year after bilateral implantation. Although the preoperative and also the postoperative median THI and TQ scores were higher in the simultaneous group, the median difference scores were equal in both groups. In the simultaneous group, tinnitus scores fluctuated in the 3 years after implantation. In the sequential group, four patients had an additional benefit of the second CI: a total suppression of tinnitus compared with their unilateral situation. While bilateral cochlear implantation can have a positive effect on preoperative tinnitus complaints, the induction of (temporary or permanent) tinnitus was also reported. Dutch Trial Register NTR1722.

[Effect of rehabilitation for prelingual deaf children who use cochlear implants in conjunction with hearing aids in the opposite ears].

PubMed

Tian, Yanjing; Zhou, Huifang; Zhang, Jing; Yang, Dong; Xu, Yi; Guo, Yuxi

2012-10-01

To compare the effect of rehabilitation of prelingual deaf children who used a cochlear implant (CI) in one ear and a hearing aids in the opposite ear while the hearing level of the opposite ears are different. Hearing ability, language ability and learning ability was included in the content. The aim of this research is to investigate better style of rehabilitation, and to offer the best help to the prelingual deaf children. Accord ing to the hearing level of the ear opposite to the one wearing a cochlear implant and whether the opposite ear wear a hearing aid or not, 30 prelingual deaf children were divided into three groups, including cochlear implant with opposite severe hearing loss and hearing aid ear (CI+SHA), cochlear implant with opposite profound hearing loss and hearing aid ear (CI+PHA), cochlear implant only (CI). The effect of rehabilitation was assessed in six different times (3,6,9,12,15 and 18 months after the cochlear implants and hearing aids began to work). The longer time the rehabilitation spends, the better the hearing ability,language ability and the learning ability were. The hearing ability of CI+SHA was better than those of CI+PHA (P<0.05) and CI (P<0.05). The language ability and learning ability of CI-SHA was nearly equal to those of the other two groups. The prelingual deaf children should take much more time on rehabilitation. The effect of rehabilitation for prelingual deaf children who used cochlear implant in one ear and hearing aid in the other depend on the residual hearing level of the other ear. If a prelingual deaf children still has any residual hearing level in the ear opposite to the cochlear implant ear, it is better for him/her to wear a hearing aid in the ear.

Altered vesicular glutamate transporter distributions in the mouse cochlear nucleus following cochlear insult

PubMed Central

Heeringa, Amarins N.; Stefanescu, Roxana A.; Raphael, Yehoash; Shore, Susan E.

2015-01-01

Vesicular glutamate transporters 1 and 2 (VGLUT1 and VGLUT2) have distinct distributions in the cochlear nucleus that correspond to the sources of the labeled terminals. VGLUT1 is mainly associated with terminals of auditory nerve fibers, whereas VGLUT2 is mainly associated with glutamatergic terminals deriving from other sources that project to the cochlear nucleus (CN), including somatosensory and vestibular terminals. Previous studies in guinea pig have shown that cochlear damage results in a decrease of VGLUT1-labeled puncta and an increase in VGLUT2-labeled puncta. This indicates cross-modal compensation that is of potential importance in somatic tinnitus. To examine whether this effect is consistent across species and to provide a background for future studies, using transgenesis, the current study examines VGLUT expression profiles upon cochlear insult by intracochlear kanamycin injections in the mouse. Intracochlear kanamycin injections abolished ipsilateral ABR responses in all animals and reduced ipsilateral spiral ganglion neuron densities in animals that were sacrificed after four weeks, but not in animals that were sacrificed after three weeks. In all unilaterally deafened animals, VGLUT1 density was decreased in CN regions that receive auditory nerve fiber terminals, i.e. in the deep layer of the dorsal cochlear nucleus (DCN), in the interstitial region where the auditory nerve enters the CN, and in the magnocellular region of the antero- and posteroventral CN. In contrast, density of VGLUT2 expression was upregulated in the fusiform cell layer of the DCN and in the granule cell lamina, which are known to receive somatosensory and vestibular terminals. These results show that a cochlear insult induces cross-modal compensation in the cochlear nucleus of the mouse, confirming previous findings in guinea pig, and that these changes are not dependent on the occurrence of spiral ganglion neuron degeneration. PMID:26705736

Altered vesicular glutamate transporter distributions in the mouse cochlear nucleus following cochlear insult.

PubMed

Heeringa, A N; Stefanescu, R A; Raphael, Y; Shore, S E

2016-02-19

Vesicular glutamate transporters 1 and 2 (VGLUT1 and VGLUT2) have distinct distributions in the cochlear nucleus that correspond to sources of the labeled terminals. VGLUT1 is mainly associated with terminals of auditory nerve fibers, whereas VGLUT2 is mainly associated with glutamatergic terminals deriving from other sources that project to the cochlear nucleus (CN), including somatosensory and vestibular terminals. Previous studies in guinea pig have shown that cochlear damage results in a decrease of VGLUT1-labeled puncta and an increase in VGLUT2-labeled puncta. This indicates cross-modal compensation that is of potential importance in somatic tinnitus. To examine whether this effect is consistent across species and to provide a background for future studies, using transgenesis, the current study examines VGLUT expression profiles upon cochlear insult by intracochlear kanamycin injections in the mouse. Intracochlear kanamycin injections abolished ipsilateral ABR responses in all animals and reduced ipsilateral spiral ganglion neuron densities in animals that were sacrificed after four weeks, but not in animals that were sacrificed after three weeks. In all unilaterally deafened animals, VGLUT1 density was decreased in CN regions that receive auditory nerve fiber terminals, i.e., in the deep layer of the dorsal cochlear nucleus (DCN), in the interstitial region where the auditory nerve enters the CN, and in the magnocellular region of the antero- and posteroventral CN. In contrast, density of VGLUT2 expression was upregulated in the fusiform cell layer of the DCN and in the granule cell lamina, which are known to receive somatosensory and vestibular terminals. These results show that a cochlear insult induces cross-modal compensation in the cochlear nucleus of the mouse, confirming previous findings in guinea pig, and that these changes are not dependent on the occurrence of spiral ganglion neuron degeneration. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Bringing Hearing to the Deaf--Cochlear Implants: a Technical and Personal Account

NASA Astrophysics Data System (ADS)

Shipsey, Ian

2006-04-01

Cochlear implants are the first device to successfully restore neural function. They have instigated a popular but controversial revolution in the treatment of deafness, and they serve as a model for research in neuroscience and biomedical engineering. In this talk the physiology of natural hearing will be reviewed from the perspective of a physicist, and the function of cochlear implants will be described in the context of historical treatments, electrical engineering, psychophysics, clinical evaluation of efficacy and personal experience. The social implications of cochlear implantation and the future outlook for auditory prostheses will also be discussed.

Microphone directionality, pre-emphasis filter, and wind noise in cochlear implants.

PubMed

Chung, King; McKibben, Nicholas

2011-10-01

Wind noise can be a nuisance or a debilitating masker for cochlear implant users in outdoor environments. Previous studies indicated that wind noise at the microphone/hearing aid output had high levels of low-frequency energy and the amount of noise generated is related to the microphone directionality. Currently, cochlear implants only offer either directional microphones or omnidirectional microphones for users at-large. As all cochlear implants utilize pre-emphasis filters to reduce low-frequency energy before the signal is encoded, effective wind noise reduction algorithms for hearing aids might not be applicable for cochlear implants. The purposes of this study were to investigate the effect of microphone directionality on speech recognition and perceived sound quality of cochlear implant users in wind noise and to derive effective wind noise reduction strategies for cochlear implants. A repeated-measure design was used to examine the effects of spectral and temporal masking created by wind noise recorded through directional and omnidirectional microphones and the effects of pre-emphasis filters on cochlear implant performance. A digital hearing aid was programmed to have linear amplification and relatively flat in-situ frequency responses for the directional and omnidirectional modes. The hearing aid output was then recorded from 0 to 360° at flow velocities of 4.5 and 13.5 m/sec in a quiet wind tunnel. Sixteen postlingually deafened adult cochlear implant listeners who reported to be able to communicate on the phone with friends and family without text messages participated in the study. Cochlear implant users listened to speech in wind noise recorded at locations that the directional and omnidirectional microphones yielded the lowest noise levels. Cochlear implant listeners repeated the sentences and rated the sound quality of the testing materials. Spectral and temporal characteristics of flow noise, as well as speech and/or noise characteristics before and after the pre-emphasis filter, were analyzed. Correlation coefficients between speech recognition scores and crest factors of wind noise before and after pre-emphasis filtering were also calculated. Listeners obtained higher scores using the omnidirectional than the directional microphone mode at 13.5 m/sec, but they obtained similar speech recognition scores for the two microphone modes at 4.5 m/sec. Higher correlation coefficients were obtained between speech recognition scores and crest factors of wind noise after pre-emphasis filtering rather than before filtering. Cochlear implant users would benefit from both directional and omnidirectional microphones to reduce far-field background noise and near-field wind noise. Automatic microphone switching algorithms can be more effective if the incoming signal were analyzed after pre-emphasis filters for microphone switching decisions. American Academy of Audiology.

Exploring the Language and Literacy Outcomes of Pediatric Cochlear Implant Users

PubMed Central

Spencer, Linda J.; Barker, Brittan A.; Tomblin, J. Bruce

2011-01-01

Objective The principal goal of this study was to investigate the relationship between language and literacy (i.e., reading and writing) skills in pediatric cochlear implant users. A peripheral objective was to identify the children's skills that were in need of remediation and subsequently to provide suggestions for remedial programming. It was predicted that the robust language skills often associated with children who have cochlear implant experience would facilitate the development of literacy skills. It was further proposed that the language and literacy skills of pediatric cochlear implant users would approximate the language and literacy skills of children with normal hearing. Design Sixteen pediatric cochlear implant users' language and literacy skills were evaluated and then compared with a reference group of 16 age-matched, normal-hearing children. All 32 participants were educated in mainstream classes within the public school system in the Midwest. The “Sentence Formulation” and “Concepts and Directions” subtests of the Clinical Evaluation of Language Fundamentals-3 test were used to evaluate receptive and expressive language skills. Reading comprehension was evaluated with the “Paragraph Comprehension” subtest of the Woodcock Reading Mastery Test. Performance measures for the writing analyses included productivity, complexity and grammaticality measures. Results Children with cochlear implants performed within 1 SD of the normal-hearing, age-matched children on measures of language comprehension, reading comprehension and writing accuracy. However, the children with cochlear implants performed significantly poorer than the children with normal hearing on the expressive “Sentence Formulation” subtest. The cochlear implant users also produced fewer words on the written narrative task than did the normal-hearing children, although there was not a significant difference between groups with respect to total words per clause. Furthermore there was a strong correlation between language performance and reading performance, as well as language performance and total words produced on the written performance measure for the children using cochlear implants. Conclusions The results of this study suggest that the language skills of pediatric cochlear implant users are related to and correlated with the development of literacy skills within these children. Consequently, the performance of the cochlear implant users, on various language and literacy measures, compared favorably to an age-matched group of children with normal hearing. There were significant differences in the ability of the cochlear implant users to correctly utilize grammatical structures such as conjunctions and correct verb forms when they were required to formulate written and oral sentences. Given this information, it would be appropriate for their educational or remedial language programs to emphasize the use and development of these structures. PMID:12799546

Is there a best side for cochlear implants in post-lingual patients?

PubMed

Amaral, Maria Stella Arantes do; Damico, Thiago A; Gonçales, Alina S; Reis, Ana C M B; Isaac, Myriam de Lima; Massuda, Eduardo T; Hyppolito, Miguel Angelo

2017-07-29

Cochlear Implant is a sensory prosthesis capable of restoring hearing in patients with severe or profound bilateral sensorineural hearing loss. To evaluate if there is a better side to be implanted in post-lingual patients. Retrospective longitudinal study. Participants were 40 subjects, of both sex, mean age of 47 years, with post-lingual hearing loss, users of unilateral cochlear implant for more than 12 months and less than 24 months, with asymmetric auditor reserve between the ears (difference of 10dBNA, In at least one of the frequencies with a response, between the ears), divided into two groups. Group A was composed of individuals with cochlear implant in the ear with better auditory reserve and Group B with auditory reserve lower in relation to the contralateral side. There was no statistical difference for the tonal auditory threshold before and after cochlear implant. A better speech perception in pre-cochlear implant tests was present in B (20%), but the final results are similar in both groups. The cochlear implant in the ear with the worst auditory residue favors a bimodal hearing, which would allow the binaural summation, without compromising the improvement of the audiometric threshold and the speech perception. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Cochlear implants and medical tourism.

PubMed

McKinnon, Brian J; Bhatt, Nishant

2010-09-01

To compare the costs of medical tourism in cochlear implant surgery performed in India as compared to the United States. In addition, the cost savings of obtaining cochlear implant surgery in India were compare d to those of other surgical interventions obtained as a medical tourist. Searches were conducted on Medline and Google using the search terms: 'medical tourism', 'medical offshoring', 'medical outsourcing', 'cochlear implants' and 'cochlear implantation'. The information regarding cost of medical treatment was obtained from personal communication with individuals familiar with India's cochlear implantation medical tourism industry. The range of cost depended on length of stay as well as the device chosen. Generally the cost, inclusive of travel, surgery and device, was in the range of $21,000-30,000, as compared to a cost range of $40,000-$60,000 in the US. With the escalating cost of healthcare in the United States, it is not surprising that some patients would seek to obtain surgical care overseas at a fraction of the cost. Participants in medical tourism often have financial resources, but lack health insurance coverage. While cardiovascular and orthopedic surgery performed outside the United States in India at centers that cater to medical tourists are often performed at one-quarter to one-third of the cost that would have been paid in the United States, the cost differential for cochlear implants is not nearly as favorable.

[Water regulation in the cochlea : Do molecular water channels facilitate potassium-dependent sound transduction?].

PubMed

Eckhard, A; Löwenheim, H

2014-06-01

Sound transduction in the cochlea critically depends on the circulation of potassium ions (K(+)) along so-called "K(+) recycling routes" between the endolymph and perilymph. These K(+) currents generate high ionic and osmotic gradients, which potentially impair the excitability of sensory hair cells and threaten cell survival in the entire cochlear duct. Molecular water channels-aquaporins (AQP)-are expressed in all cochlear supporting cells along the K(+) recycling routes; however, their significance for osmotic equilibration in cochlear duct cells is unknown. The diffusive and osmotic water permeabilies of Reissner's membrane, the organ of Corti and the entire cochlear duct epithelium were determined. Expression of the potassium channel Kir4.1 and the water channel AQP4 in the cochlear duct was investigated by immunohistochemistry. The calculated water permeability values indicate the extent of AQP-facilitated water flux across the cochlear duct epithelium. Immunohistochemically, Kir4.1 and AQP4 were found to colocalize in distinct membrane domains of supporting cells along the K(+)-recycling routes. These observations suggest the presence of a rapid AQP-mediated water exchange between the endolymph, the cells of the cochlear duct and the perilymph. The subcellular colocalization of Kir4.1 and AQP4 in epithelial supporting cells indicates functional coupling of potassium and water flow in the cochlea. Finally, this offers an explanation for the hearing impairment observed in individuals with mutations in the AQP4 gene.

Bilateral cochlear implantation in the ferret: A novel animal model for behavioral studies

PubMed Central

Hartley, Douglas E.H.; Vongpaisal, Tara; Xu, Jin; Shepherd, Robert K.; King, Andrew J.; Isaiah, Amal

2010-01-01

Bilateral cochlear implantation has recently been introduced with the aim of improving both speech perception in background noise and sound localization. Although evidence suggests that binaural perception is possible with two cochlear implants, results in humans are variable. To explore potential contributing factors to these variable outcomes, we have developed a behavioral animal model of bilateral cochlear implantation in a novel species, the ferret. Although ferrets are ideally suited to psychophysical and physiological assessments of binaural hearing, cochlear implantation has not been previously described in this species. This paper describes the techniques of deafening with aminoglycoside administration, surgical implantation of an intracochlear array and chronic intracochlear electrical stimulation with monitoring for electrode integrity and efficacy of stimulation. Experiments have been presented elsewhere to show that the model can be used to study behavioral and electrophysiological measures of binaural hearing in chronically implanted animals. This paper demonstrates that cochlear implantation and chronic intracochlear electrical stimulation are both safe and effective in ferrets, opening up the possibility of using this model to study potential protective effects of bilateral cochlear implantation on the developing central auditory pathway. Since ferrets can be used to assess psychophysical and physiological aspects of hearing along with the structure of the auditory pathway in the same animals, we anticipate that this model will help develop novel neuroprosthetic therapies for use in humans. PMID:20576507

Large vestibular aqueduct syndrome: Impedance changes over time with different cochlear implant electrode arrays.

PubMed

Powell, Harry R F; Birman, Catherine S

2015-01-01

The aim of this study was to assess if large vestibular aqueduct syndrome (LVAS), with the increase in perilymphatic pressure, affects impedance changes over time with different types of Cochlear(®) implant electrode arrays Contour, Straight, and CI 422. To report speech perception outcomes for these cochlear implant recipients. Retrospective case review of impedance levels and categories of auditory performance. Impedance data were collected at switch on, 1 month, 3, 6, 12, and 24 months after cochlear implantation and compared with control (non-LVAS cochlear implant recipient) data for each array type. Forty-seven patients with exclusive LVAS and no other vestibulocochlear abnormalities or other identifiable cause of deafness were eligible for inclusion in the study. In LVAS patients, there was a significant difference in impedance between the three types of device (P < 0.0001). Time since switch on was associated with a decrease in impedance for all three devices (P < 0.0001). The mean impedance reduced between switch on and 1 month and remained relatively constant thereafter. Sound variation with softening of sounds was seen in four CI 422 (Straight Research Array) recipients due to ongoing fluctuations in electrode compliance. For all three array types, there was no significant difference in the mean impedance between the LVAS patients and controls over the first 12 months. In keeping with previous studies cochlear implant recipients with LVAS hear very well through the cochlear implant.

The Influence of Cochlear Mechanical Dysfunction, Temporal Processing Deficits, and Age on the Intelligibility of Audible Speech in Noise for Hearing-Impaired Listeners

PubMed Central

Johannesen, Peter T.; Pérez-González, Patricia; Kalluri, Sridhar; Blanco, José L.

2016-01-01

The aim of this study was to assess the relative importance of cochlear mechanical dysfunction, temporal processing deficits, and age on the ability of hearing-impaired listeners to understand speech in noisy backgrounds. Sixty-eight listeners took part in the study. They were provided with linear, frequency-specific amplification to compensate for their audiometric losses, and intelligibility was assessed for speech-shaped noise (SSN) and a time-reversed two-talker masker (R2TM). Behavioral estimates of cochlear gain loss and residual compression were available from a previous study and were used as indicators of cochlear mechanical dysfunction. Temporal processing abilities were assessed using frequency modulation detection thresholds. Age, audiometric thresholds, and the difference between audiometric threshold and cochlear gain loss were also included in the analyses. Stepwise multiple linear regression models were used to assess the relative importance of the various factors for intelligibility. Results showed that (a) cochlear gain loss was unrelated to intelligibility, (b) residual cochlear compression was related to intelligibility in SSN but not in a R2TM, (c) temporal processing was strongly related to intelligibility in a R2TM and much less so in SSN, and (d) age per se impaired intelligibility. In summary, all factors affected intelligibility, but their relative importance varied across maskers. PMID:27604779

Excitation Patterns of Standard and Steered Partial Tripolar Stimuli in Cochlear Implants.

PubMed

Wu, Ching-Chih; Luo, Xin

2016-04-01

Current steering in partial tripolar (pTP) mode has been shown to improve pitch perception and spectral resolution with cochlear implants (CIs). In this mode, a fraction (σ) of the main electrode current is returned within the cochlea and steered between the basal and apical flanking electrodes (with a proportion of α and 1 - α, respectively). Pitch generally decreases when α increases from 0 to 1, although the salience of pitch change varies across CI users. This study aimed to identify the mechanism of pitch changes with pTP-mode current steering and the factors contributing to the intersubject variability in pitch-ranking sensitivity. The electrical fields were measured for steered pTP stimuli on the same main electrode with α = 0, 0.5, and 1 in five implanted ears using electrical field imaging (EFI). The related excitation patterns were also measured physiologically using evoked compound action potential (ECAP) and psychophysically using psychophysical forward masking (PFM). Consistent with the pitch-ranking results in this study, the EFI, ECAP, and PFM centroids shifted apically with increasing α. An apical shift was also observed for the PFM peak but not for the EFI or ECAP peak. The pattern width was similar with different α values within a given measure (e.g., EFI, ECAP, or PFM), but the ECAP patterns were broader than the EFI and PFM patterns, possibly because ECAP was measured with smaller σ values than EFI and PFM. The amount of pattern shift with α depended on σ (i.e., the total amount of current used for steering) but was not correlated with the pitch-ranking sensitivity across subjects. The results revealed that the pitch changes elicited by pTP-mode current steering were not only driven by the shifts of excitation centroid.

Parents' Views on Changing Communication after Cochlear Implantation

ERIC Educational Resources Information Center

Watson, Linda M.; Hardie, Tim; Archbold, Sue M.; Wheeler, Alexandra

2008-01-01

We sent questionnaires to families of all 288 children who had received cochlear implants at one center in the United Kingdom at least 5 years previously. Thus, it was a large, unselected group. We received 142 replies and 119 indicated that the child and family had changed their communication approach following cochlear implantation. In 113 cases…

Changes in Speech Production in an Early Deafened Adult with a Cochlear Implant

ERIC Educational Resources Information Center

Wong, Patrick C. M.

2007-01-01

Background and Aims: The current study is a first investigation reporting the speech production characteristics of an early deafened adult cochlear implant user after a course of speech-language treatment. Methods and Procedures: The participant is culturally deaf and received the cochlear implant when she was 43 years old. A 24-week ABCABC…

The Self-Regulation of a Child with Cochlear Implants within a School Environment

ERIC Educational Resources Information Center

Patton, Kristin L.

2013-01-01

The purpose of this qualitative research, which utilized a narrative design strategy, was to describe the process of self-regulation of a child who has bilateral cochlear implants within the social environment of school. The study investigated the use of self-regulatory strategies by the cochlear implant recipient. It also examined how the child…

Cochlear Implantation for Children with Hearing Loss and Multiple Disabilities: An Evaluation from an Educator's Perspective

ERIC Educational Resources Information Center

Bertram, Bodo

2004-01-01

In recent years, parents of children with hearing loss and various additional disabilities have shown increasing interest in cochlear implants. This article describes how the program in Hanover, Germany is attempting to respond to this interest. It discusses the selection process for children who receive cochlear implants who have multiple…

Spelling in Written Stories by School-Age Children with Cochlear Implants

ERIC Educational Resources Information Center

Straley, Sara G.; Werfel, Krystal L.; Hendricks, Alison Eisel

2016-01-01

This study evaluated the spelling of 3rd to 6th grade children with cochlear implants in written stories. Spelling was analysed using traditional correct/incorrect scoring as well as the Spelling Sensitivity Score, which provides linguistic information about spelling attempts. Children with cochlear implants spelled 86 per cent of words in stories…

Identification of Pure-Tone Audiologic Thresholds for Pediatric Cochlear Implant Candidacy: A Systematic Review.

PubMed

de Kleijn, Jasper L; van Kalmthout, Ludwike W M; van der Vossen, Martijn J B; Vonck, Bernard M D; Topsakal, Vedat; Bruijnzeel, Hanneke

2018-05-24

Although current guidelines recommend cochlear implantation only for children with profound hearing impairment (HI) (>90 decibel [dB] hearing level [HL]), studies show that children with severe hearing impairment (>70-90 dB HL) could also benefit from cochlear implantation. To perform a systematic review to identify audiologic thresholds (in dB HL) that could serve as an audiologic candidacy criterion for pediatric cochlear implantation using 4 domains of speech and language development as independent outcome measures (speech production, speech perception, receptive language, and auditory performance). PubMed and Embase databases were searched up to June 28, 2017, to identify studies comparing speech and language development between children who were profoundly deaf using cochlear implants and children with severe hearing loss using hearing aids, because no studies are available directly comparing children with severe HI in both groups. If cochlear implant users with profound HI score better on speech and language tests than those with severe HI who use hearing aids, this outcome could support adjusting cochlear implantation candidacy criteria to lower audiologic thresholds. Literature search, screening, and article selection were performed using a predefined strategy. Article screening was executed independently by 4 authors in 2 pairs; consensus on article inclusion was reached by discussion between these 4 authors. This study is reported according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. Title and abstract screening of 2822 articles resulted in selection of 130 articles for full-text review. Twenty-one studies were selected for critical appraisal, resulting in selection of 10 articles for data extraction. Two studies formulated audiologic thresholds (in dB HLs) at which children could qualify for cochlear implantation: (1) at 4-frequency pure-tone average (PTA) thresholds of 80 dB HL or greater based on speech perception and auditory performance subtests and (2) at PTA thresholds of 88 and 96 dB HL based on a speech perception subtest. In 8 of the 18 outcome measures, children with profound HI using cochlear implants performed similarly to children with severe HI using hearing aids. Better performance of cochlear implant users was shown with a picture-naming test and a speech perception in noise test. Owing to large heterogeneity in study population and selected tests, it was not possible to conduct a meta-analysis. Studies indicate that lower audiologic thresholds (≥80 dB HL) than are advised in current national and manufacturer guidelines would be appropriate as audiologic candidacy criteria for pediatric cochlear implantation.

Modeling Open-Set Spoken Word Recognition in Postlingually Deafened Adults after Cochlear Implantation: Some Preliminary Results with the Neighborhood Activation Model

PubMed Central

Meyer, Ted A.; Frisch, Stefan A.; Pisoni, David B.; Miyamoto, Richard T.; Svirsky, Mario A.

2012-01-01

Hypotheses Do cochlear implants provide enough information to allow adult cochlear implant users to understand words in ways that are similar to listeners with acoustic hearing? Can we use a computational model to gain insight into the underlying mechanisms used by cochlear implant users to recognize spoken words? Background The Neighborhood Activation Model has been shown to be a reasonable model of word recognition for listeners with normal hearing. The Neighborhood Activation Model assumes that words are recognized in relation to other similar-sounding words in a listener’s lexicon. The probability of correctly identifying a word is based on the phoneme perception probabilities from a listener’s closed-set consonant and vowel confusion matrices modified by the relative frequency of occurrence of the target word compared with similar-sounding words (neighbors). Common words with few similar-sounding neighbors are more likely to be selected as responses than less common words with many similar-sounding neighbors. Recent studies have shown that several of the assumptions of the Neighborhood Activation Model also hold true for cochlear implant users. Methods Closed-set consonant and vowel confusion matrices were obtained from 26 postlingually deafened adults who use cochlear implants. Confusion matrices were used to represent input errors to the Neighborhood Activation Model. Responses to the different stimuli were then generated by the Neighborhood Activation Model after incorporating the frequency of occurrence counts of the stimuli and their neighbors. Model outputs were compared with obtained performance measures on the Consonant-Vowel Nucleus-Consonant word test. Information transmission analysis was used to assess whether the Neighborhood Activation Model was able to successfully generate and predict word and individual phoneme recognition by cochlear implant users. Results The Neighborhood Activation Model predicted Consonant-Vowel Nucleus-Consonant test words at levels similar to those correctly identified by the cochlear implant users. The Neighborhood Activation Model also predicted phoneme feature information well. Conclusion The results obtained suggest that the Neighborhood Activation Model provides a reasonable explanation of word recognition by postlingually deafened adults after cochlear implantation. It appears that multichannel cochlear implants give cochlear implant users access to their mental lexicons in a manner that is similar to listeners with acoustic hearing. The lexical properties of the test stimuli used to assess performance are important to spoken-word recognition and should be included in further models of the word recognition process. PMID:12851554

Evaluation on health-related quality of life in deaf children with cochlear implant in China.

PubMed

Liu, Hong; Liu, Hong-Xiang; Kang, Hou-Yong; Gu, Zheng; Hong, Su-Ling

2016-09-01

Previous studies have shown that deaf children benefit considerably from cochlear implants. These improvements are found in areas such as speech perception, speech production, and audiology-verbal performance. Despite the increasing prevalence of cochlear implants in China, few studies have reported on health-related quality of life in children with cochlear implants. The main objective of this study was to explore health-related quality of life on children with cochlear implants in South-west China. A retrospective observational study of 213 CI users in Southwest China between 2010 and 2013. Participants were 213 individuals with bilateral severe-to-profound hearing loss who wore unilateral cochlear implants. The Nijmegen Cochlear Implant Questionnaire and Health Utility Index Mark III were used pre-implantation and 1 year post-implantation. Additionally, 1-year postoperative scores for Mandarin speech perception were compared with preoperative scores. Health-related quality of life improved post-operation with scores on the Nijmegen Cochlear Implant Questionnaire improving significantly in all subdomains, and the Health Utility Index 3 showing a significant improvement in the utility score and the subdomains of ''hearing," ''speech," and "emotion". Additionally, a significant improvement in speech recognition scores was found. No significant correlation was found between increased in quality of life and speech perception scores. Health-related quality of life and speech recognition in prelingual deaf children significantly improved post-operation. The lack of correlation between quality of life and speech perception suggests that when evaluating performance post-implantation in prelingual deaf children and adolescents, measures of both speech perception and quality of life should be used. Copyright © 2016. Published by Elsevier Ireland Ltd.

Jervell and Lange-Nielsen syndrome in cochlear implanted patients: our experience and a review of literature.

PubMed

Eftekharian, Ali; Mahani, Mozhgan Hosseinerezai

2015-09-01

To share our experience in cochlear implanted patients with Jervell and Lange-Nielsen syndrome (JLNS), to review the literature results and to disclose precautions which have to be taken dealing with these patients. Electrocardiograms (ECG) of 503 children with congenital bilateral profound hearing loss which were cochlear implanted in cochlear implant center of a tertiary hospital were evaluated for long QT syndrome. Clinical reports of the patients with JLNS were evaluated and a review of literature performed. The prevalence of disease was 0.79% (four cases) in our center which is in the range of literature reports (0-2.6%). None of our patients had a history of syncopal attack. Two patients (50%) were born from parents with consanguineous marriage. Considering all precautions their cochlear implant surgeries were done uneventfully. A review of the literature has identified sixteen reports on cochlear implantation in a total of 38 children with JLNS. Similar to our cases none of the authors reported cardiac events during device switch-on. Nine available reports about the outcome of cochlear implantation in these patients indicated good auditory outcome. It is recommended that all congenitally deaf patients have an ECG taken as a part of the evaluation. As auditory stimuli is reported to be a specific trigger, it is prudent to activate the processor with continuous heart monitoring even though there is no reported cardiac event during device switch-on. Cochlear implantation can be performed relatively safely in these patients if necessary precautions have been taken appropriately and their auditory outcome is good. Triggers of the cardiac events should be avoided throughout their life. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Assessment of the cochlear nerve to facial nerve size ratio using MR multiplanar reconstruction of the internal auditory canal in patients presenting with acquired long-standing hearing loss

PubMed Central

Hey, Constanze; Shaaban, Mohamed S; Elabd, Amr M; Hassan, Hebatallah H M; Gruber-Rouh, Tatjana; Kaltenbach, Benjamin; Harth, Marc; Ackermann, Hanns; Stöver, Timo; Vogl, Thomas J; Nour-Eldin, Nour-Eldin A

2017-01-01

Objective: To test using the facial nerve as a reference for assessment of the cochlear nerve size in patients with acquired long-standing sensorineural hearing loss (SNHL) using MRI multiplanar reconstruction. Methods: The study was retrospectively performed on 86 patients. Group 1 (study group, n = 53) with bilateral long-standing SNHL. Group 2 (control group, n = 33) without hearing loss. The nerve size was measured by drawing a region of interest around the cross-sectional circumference of the nerve in multiplanar reconstruction images. Results: No significant correlation was noted between the cochlear nerve and facial nerve size, and the patient's age, gender and weight (p > 0.05). In Group 1, the mean ratio of the cochlear to facial nerve size was 0.99 ± 0.30 (range: 0.52–1.86) and 1.12 ± 0.35 (range: 0.34–2.3) for the right and left sides, respectively. In Group 2, it was 1.18 ± 0.23 (range: 0.78–1.71) and 1.25 ± 0.25 (range: 0.85–1.94) for the right and left sides, respectively. The cochlear nerve size was statistically (p = 0.0004) smaller in Group 1 than in Group 2. Conclusion: The cochlear nerve size and the cochlear to facial nerve size ratio are significantly smaller in patients with acquired long-standing SNHL. Advances in knowledge: The facial nerve can be used as a reference for assessment of the cochlear nerve in patients with acquired long-standing SNHL. PMID:28368665

Cochlear microphonic broad tuning curves

NASA Astrophysics Data System (ADS)

Ayat, Mohammad; Teal, Paul D.; Searchfield, Grant D.; Razali, Najwani

2015-12-01

It is known that the cochlear microphonic voltage exhibits much broader tuning than does the basilar membrane motion. The most commonly used explanation for this is that when an electrode is inserted at a particular point inside the scala media, the microphonic potentials of neighbouring hair cells have different phases, leading to cancelation at the electrodes location. In situ recording of functioning outer hair cells (OHCs) for investigating this hypothesis is exceptionally difficult. Therefore, to investigate the discrepancy between the tuning curves of the basilar membrane and those of the cochlear microphonic, and the effect of phase cancellation of adjacent hair cells on the broadness of the cochlear microphonic tuning curves, we use an electromechanical model of the cochlea to devise an experiment. We explore the effect of adjacent hair cells (i.e., longitudinal phase cancellation) on the broadness of the cochlear microphonic tuning curves in different locations. The results of the experiment indicate that active longitudinal coupling (i.e., coupling with active adjacent outer hair cells) only slightly changes the broadness of the CM tuning curves. The results also demonstrate that there is a π phase difference between the potentials produced by the hair bundle and the soma near the place associated with the characteristic frequency based on place-frequency maps (i.e., the best place). We suggest that the transversal phase cancellation (caused by the phase difference between the hair bundle and the soma) plays a far more important role than longitudinal phase cancellation in the broadness of the cochlear microphonic tuning curves. Moreover, by increasing the modelled longitudinal resistance resulting the cochlear microphonic curves exhibiting sharper tuning. The results of the simulations suggest that the passive network of the organ of Corti determines the phase difference between the hair bundle and soma, and hence determines the sharpness of the cochlear microphonic tuning curves.

The auditory nerve overlapped waveform (ANOW): A new objective measure of low-frequency hearing

NASA Astrophysics Data System (ADS)

Lichtenhan, Jeffery T.; Salt, Alec N.; Guinan, John J.

2015-12-01

One of the most pressing problems today in the mechanics of hearing is to understand the mechanical motions in the apical half of the cochlea. Almost all available measurements from the cochlear apex of basilar membrane or other organ-of-Corti transverse motion have been made from ears where the health, or sensitivity, in the apical half of the cochlea was not known. A key step in understanding the mechanics of the cochlear base was to trust mechanical measurements only when objective measures from auditory-nerve compound action potentials (CAPs) showed good preparation sensitivity. However, such traditional objective measures are not adequate monitors of cochlear health in the very low-frequency regions of the apex that are accessible for mechanical measurements. To address this problem, we developed the Auditory Nerve Overlapped Waveform (ANOW) that originates from auditory nerve output in the apex. When responses from the round window to alternating low-frequency tones are averaged, the cochlear microphonic is canceled and phase-locked neural firing interleaves in time (i.e., overlaps). The result is a waveform that oscillates at twice the probe frequency. We have demonstrated that this Auditory Nerve Overlapped Waveform - called ANOW - originates from auditory nerve fibers in the cochlear apex [8], relates well to single-auditory-nerve-fiber thresholds, and can provide an objective estimate of low-frequency sensitivity [7]. Our new experiments demonstrate that ANOW is a highly sensitive indicator of apical cochlear function. During four different manipulations to the scala media along the cochlear spiral, ANOW amplitude changed when either no, or only small, changes occurred in CAP thresholds. Overall, our results demonstrate that ANOW can be used to monitor cochlear sensitivity of low-frequency regions during experiments that make apical basilar membrane motion measurements.

Cochlear implantation in autistic children with profound sensorineural hearing loss.

PubMed

Lachowska, Magdalena; Pastuszka, Agnieszka; Łukaszewicz-Moszyńska, Zuzanna; Mikołajewska, Lidia; Niemczyk, Kazimierz

2016-11-19

Cochlear implants have become the method of choice for the treatment of severe-to-profound hearing loss in both children and adults. Its benefits are well documented in the pediatric and adult population. Also deaf children with additional needs, including autism, have been covered by this treatment. The aim of this study was to assess the benefits from cochlear implantation in deafened children with autism as the only additional disability. This study analyzes data of six children. The follow-up time was at least 43 months. The following data were analyzed: medical history, reaction to music and sound, Ling's six sounds test, onomatopoeic word test, reaction to spoken child's name, response to requests, questionnaire given to parents, sound processor fitting sessions and data. After cochlear implantation each child presented other communication skills. In some children, the symptoms of speech understanding were observed. No increased hyperactivity associated with daily use cochlear implant was observed. The study showed that in autistic children the perception is very important for a child's sense of security and makes contact with parents easier. Our study showed that oral communication is not likely to be a realistic goal in children with cochlear implants and autism. The implantation results showed benefits that varied among those children. The traditional methods of evaluating the results of cochlear implantation in children with autism are usually insufficient to fully assess the functional benefits. These benefits should be assessed in a more comprehensive manner taking into account the limitations of communication resulting from the essence of autism. It is important that we share knowledge about these complex children with cochlear implants. Copyright © 2016 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Music training improves pitch perception in prelingually deafened children with cochlear implants.

PubMed

Chen, Joshua Kuang-Chao; Chuang, Ann Yi Chiun; McMahon, Catherine; Hsieh, Jen-Chuen; Tung, Tao-Hsin; Li, Lieber Po-Hung

2010-04-01

The comparatively poor music appreciation in patients with cochlear implants might be ascribed to an inadequate exposure to music; however, the effect of training on music perception in prelingually deafened children with cochlear implants remains unknown. This study aimed to investigate whether previous musical education improves pitch perception ability in these children. Twenty-seven children with congenital/prelingual deafness of profound degree were studied. Test stimuli consisted of 2 sequential piano tones, ranging from C (256 Hz) to B (495 Hz). Children were asked to identify the pitch relationship between the 2 tones (same, higher, or lower). Effects of musical training duration, pitch-interval size, current age, age of implantation, gender, and type of cochlear implant on accuracy of pitch perception were evaluated. The duration of musical training positively correlated with the correct rate of pitch perception. Pitch perception performance was better in children who had a cochlear implant and were older than 6 years than in those who were aged < or =6 years (ie, preschool). Effect of pitch-interval size was insignificant on pitch perception, and there was no correlation between pitch perception and the age of implantation, gender, or type of cochlear implant. Musical training seems to improve pitch perception ability in prelingually deafened children with a cochlear implant. Auditory plasticity might play an important role in such enhancement. This suggests that incorporation of a structured training program on music perception early in life and as part of the postoperative rehabilitation program for prelingually deafened children with cochlear implants would be beneficial. A longitudinal study is needed to show whether improvement of music performance in these children is measurable by use of auditory evoked potentials.

Auditory Speech Perception Development in Relation to Patient's Age with Cochlear Implant

PubMed Central

Ciscare, Grace Kelly Seixas; Mantello, Erika Barioni; Fortunato-Queiroz, Carla Aparecida Urzedo; Hyppolito, Miguel Angelo; Reis, Ana Cláudia Mirândola Barbosa dos

2017-01-01

Introduction  A cochlear implant in adolescent patients with pre-lingual deafness is still a debatable issue. Objective  The objective of this study is to analyze and compare the development of auditory speech perception in children with pre-lingual auditory impairment submitted to cochlear implant, in different age groups in the first year after implantation. Method  This is a retrospective study, documentary research, in which we analyzed 78 reports of children with severe bilateral sensorineural hearing loss, unilateral cochlear implant users of both sexes. They were divided into three groups: G1, 22 infants aged less than 42 months; G2, 28 infants aged between 43 to 83 months; and G3, 28 older than 84 months. We collected medical record data to characterize the patients, auditory thresholds with cochlear implants, assessment of speech perception, and auditory skills. Results  There was no statistical difference in the association of the results among groups G1, G2, and G3 with sex, caregiver education level, city of residence, and speech perception level. There was a moderate correlation between age and hearing aid use time, age and cochlear implants use time. There was a strong correlation between age and the age cochlear implants was performed, hearing aid use time and age CI was performed. Conclusion  There was no statistical difference in the speech perception in relation to the patient's age when cochlear implant was performed. There were statistically significant differences for the variables of auditory deprivation time between G3 - G1 and G2 - G1 and hearing aid use time between G3 - G2 and G3 - G1. PMID:28680487

Auditory Mechanics of the Tectorial Membrane and the Cochlear Spiral

PubMed Central

Gavara, Núria; Manoussaki, Daphne; Chadwick, Richard S.

2012-01-01

Purpose of review This review is timely and relevant since new experimental and theoretical findings suggest that cochlear mechanics from the nanoscale to the macroscale are affected by mechanical properties of the tectorial membrane and the spiral shape. Recent findings Main tectorial membrane themes covered are i) composition and morphology, ii) nanoscale mechanical interactions with the outer hair cell bundle, iii) macroscale longitudinal coupling, iv) fluid interaction with inner hair cell bundles, v) macroscale dynamics and waves. Main cochlear spiral themes are macroscale low-frequency energy focusing and microscale organ of Corti shear gain. Implications Findings from new experimental and theoretical models reveal exquisite sensitivity of cochlear mechanical performance to tectorial membrane structural organization, mechanics, and its positioning with respect to hair bundles. The cochlear spiral geometry is a major determinant of low frequency hearing. Suggestions are made for future research directions. PMID:21785353

[Pre-operation evaluation and intra-operation management of cochlear implantation].

PubMed

Zhang, Dao-xing; Hu, Bao-hua; Xiao, Yu-li; Shi, Bo-ning

2004-10-01

To summarize pre-operation evaluation experiences in cochlear implantation. Performing auditory evaluation and image analysis seriously in 158 severe hearing loss or total deaf cases before cochlear implantation, comparing their performance with the findings during and post operation. Among the total 158 cases, 116 cases with normal structure, 42 cases with the abnormal findings of the inner or middle ear. Stapedial gusher happened in 6 cases, 1 case was not predicted before operation. Except 1 case with serious malformation, the findings of other 157 cases in operation were consistent with the pre-operation evaluation. We helped all patients reconstruct auditory conduction with cochlear implantation, and the average hearing level up to 37.6 dB SPL. Performing image analysis seriously before operation and planning for operation according to HRCT can do great help to cochlear implantation. The operation under the HRCT instruction has less complications.

Congenitally deafblind children and cochlear implants: effects on communication.

PubMed

Dammeyer, Jesper

2009-01-01

There has been much research conducted demonstrating the positive benefits of cochlear implantation (CI) in children who are deaf. Research on CI in children who are both deaf and blind, however, is lacking. The purpose of this article is to present a study of five congenitally deafblind children who received cochlear implants between 2.2 and 4.2 years of age. Ratings of video observations were used to measure the children's early communication development with and without the use of their cochlear implants. In addition, parental interviews were used to assess the benefits parents perceived regarding their children's cochlear implants. Two examples are included in this article to illustrate the parents' perspectives about CI in their deafblind children. Benefits of CI in this cohort of children included improved attention and emotional response as well as greater use of objects in interaction with adults. The best overall outcome of CI is not spoken language but better communication.

Deep brain stimulation with a pre-existing cochlear implant: Surgical technique and outcome.

PubMed

Eddelman, Daniel; Wewel, Joshua; Wiet, R Mark; Metman, Leo V; Sani, Sepehr

2017-01-01

Patients with previously implanted cranial devices pose a special challenge in deep brain stimulation (DBS) surgery. We report the implantation of bilateral DBS leads in a patient with a cochlear implant. Technical nuances and long-term interdevice functionality are presented. A 70-year-old patient with advancing Parkinson's disease and a previously placed cochlear implant for sensorineural hearing loss was referred for placement of bilateral DBS in the subthalamic nucleus (STN). Prior to DBS, the patient underwent surgical removal of the subgaleal cochlear magnet, followed by stereotactic MRI, frame placement, stereotactic computed tomography (CT), and merging of imaging studies. This technique allowed for successful computational merging, MRI-guided targeting, and lead implantation with acceptable accuracy. Formal testing and programming of both the devices were successful without electrical interference. Successful DBS implantation with high resolution MRI-guided targeting is technically feasible in patients with previously implanted cochlear implants by following proper precautions.

Disorders of cochlear blood flow.

PubMed

Nakashima, Tsutomu; Naganawa, Shinji; Sone, Michihiko; Tominaga, Mitsuo; Hayashi, Hideo; Yamamoto, Hiroshi; Liu, Xiuli; Nuttall, Alfred L

2003-09-01

The cochlea is principally supplied from the inner ear artery (labyrinthine artery), which is usually a branch of the anterior inferior cerebellar artery. Cochlear blood flow is a function of cochlear perfusion pressure, which is calculated as the difference between mean arterial blood pressure and inner ear fluid pressure. Many otologic disorders such as noise-induced hearing loss, endolymphatic hydrops and presbycusis are suspected of being related to alterations in cochlear blood flow. However, the human cochlea is not easily accessible for investigation because this delicate sensory organ is hidden deep in the temporal bone. In patients with sensorineural hearing loss, magnetic resonance imaging, laser-Doppler flowmetry and ultrasonography have been used to investigate the status of cochlear blood flow. There have been many reports of hearing loss that were considered to be caused by blood flow disturbance in the cochlea. However, direct evidence of blood flow disturbance in the cochlea is still lacking in most of the cases.

Conditional Deletion of N-Myc Disrupts Neurosensory and Non-sensory Development of the Ear

PubMed Central

Kopecky, Benjamin; Santi, Peter; Johnson, Shane; Schmitz, Heather; Fritzsch, Bernd

2011-01-01

Ear development requires interactions of transcription factors for proliferation and differentiation. The proto-oncogene N-Myc is a member of the Myc family that regulate proliferation. To investigate the function of N-Myc, we conditionally knocked out N-Myc in the ear using Tg(Pax2-Cre) and Foxg 1KiCre. N-Myc CKOs had reduced growth of the ear, abnormal morphology including fused sensory epithelia, disrupted histology, and disorganized neuronal innervation. Using Thin-Sheet Laser Imaging Microscopy (TSLIM), 3D reconstruction and quantification of the cochlea revealed a greater than fifty percent size reduction. Immunochemistry and in situ hybridization showed a gravistatic organ-cochlear fusion and a “circularized” apex with no clear inner and outer hair cells. Furthermore, the abnormally developed cochlea had cross innervation from the vestibular ganglion near the basal tip. These findings are put in the context of the possible functional relationship of N-Myc with a number of other cell proliferative and fate determining genes during ear development. PMID:21448975

Language, Mental State Vocabulary, and False Belief Understanding in Children with Cochlear Implants

ERIC Educational Resources Information Center

Peters, Kimberly; Remmel, Ethan; Richards, Debra

2009-01-01

Purpose: This study examined false belief understanding and its predictors in school-age children who are deaf with cochlear implants and who use spoken language. Method: False belief understanding was measured through an explanation-of-action task in 30 children between the ages of 3 and 12 years who used cochlear implants. Children told a…

Cyborgization: Deaf Education for Young Children in the Cochlear Implantation Era

ERIC Educational Resources Information Center

Valente, Joseph Michael

2011-01-01

The author, who was raised oral deaf himself, recounts a visit to a school for young deaf children and discovers that young d/Deaf children and their rights are subverted by the cochlear implantation empire. The hypercapitalist, techno-manic times of cochlear implantation has wreaked havoc to the lives of not only young children with deafness but…

Cochlear Implants. National Institutes of Health Consensus Development Conference Statement (May 4, 1988). Volume 7, Number 2.

ERIC Educational Resources Information Center

National Institutes of Health (DHHS), Bethesda, MD.

This paper reports the results of a Consensus Development Conference on Cochlear Implants sponsored by the National Institutes of Health to improve the hearing of children and adults with hearing impairments. The following questions are addressed: (1) Who is a suitable candidate for a cochlear implant? (2) What are the advantages and disadvantages…

Auditory Environment across the Life Span of Cochlear Implant Users: Insights from Data Logging

ERIC Educational Resources Information Center

Busch, Tobias; Vanpoucke, Filiep; van Wieringen, Astrid

2017-01-01

Purpose: We describe the natural auditory environment of people with cochlear implants (CIs), how it changes across the life span, and how it varies between individuals. Method: We performed a retrospective cross-sectional analysis of Cochlear Nucleus 6 CI sound-processor data logs. The logs were obtained from 1,501 people with CIs (ages 0-96…

Congenitally Deafblind Children and Cochlear Implants: Effects on Communication

ERIC Educational Resources Information Center

Dammeyer, Jesper

2009-01-01

There has been much research conducted demonstrating the positive benefits of cochlear implantation (CI) in children who are deaf. Research on CI in children who are both deaf and blind, however, is lacking. The purpose of this article is to present a study of five congenitally deafblind children who received cochlear implants between 2.2 and 4.2…

Searching for Cochlear Implant Information on the Internet Maze: Implications for Parents and Professionals

ERIC Educational Resources Information Center

Zaidman-Zait, Anat; Jamieson, Janet R.

2004-01-01

The present study has three purposes: (a) to determine who disseminates information on cochlear implants on the Web; (b) to describe a representative sample of Web sites that disseminate information on cochlear implants, with a focus on the content topics and their relevance to parents of deaf children; and (c) to discuss the practical issues of…

Benefit of Wearing a Hearing Aid on the Unimplanted Ear in Adult Users of a Cochlear Implant

ERIC Educational Resources Information Center

Dunn, Camille C.; Tyler, Richard S.; Witt, Shelley A.

2005-01-01

The purpose of this investigation was to document performance of participants wearing a cochlear implant and hearing aid in opposite ears on speech-perception and localization tests. Twelve individuals who wore a cochlear implant and a hearing aid on contralateral ears were tested on their abilities to understand words in quiet and sentences in…

A Longitudinal Study in Children with Sequential Bilateral Cochlear Implants: Time Course for the Second Implanted Ear and Bilateral Performance

ERIC Educational Resources Information Center

Reeder, Ruth M.; Firszt, Jill B.; Cadieux, Jamie H.; Strube, Michael J.

2017-01-01

Purpose: Whether, and if so when, a second-ear cochlear implant should be provided to older, unilaterally implanted children is an ongoing clinical question. This study evaluated rate of speech recognition progress for the second implanted ear and with bilateral cochlear implants in older sequentially implanted children and evaluated localization…

Educational Interpreters: Meeting the Communication Needs of Children with Cochlear Implants

ERIC Educational Resources Information Center

Melton, Julie; Higbee, Renee

2013-01-01

Since the early 1990s, when the U.S. Food and Drug Administration approved cochlear implants for deaf and hard of hearing children, the number of children who have cochlear implants has increased in mainstream settings. Recent research suggests that these students, like their deaf and hard of hearing peers without implants who use sign language,…

Prevention and management of cochlear implant infections.

PubMed

Gluth, Michael B; Singh, Rajesh; Atlas, Marcus D

2011-11-01

Understanding the issues of infection related to an implantable medical device is crucial to all cochlear implant teams. Furthermore, given the risk of central nervous system complications and the relatively high quantity of underlying resource investment associated with cochlear implantation, the stakes of infection are high. The optimal strategies to prevent and manage such infections are still evolving as good-quality prospective data to guide such management decisions are not yet abundant within the medical literature and many recommendations are based on retrospective reviews or anecdotal evidence. We will outline a general strategy to deal with cochlear implant-related infection based on both the authors' experience and the published literature.

Use of Neural Response Telemetry for Pediatric Cochlear Implants: Current Practice.

PubMed

Almosnino, Galit; Anne, Samantha; Schwartz, Seth R

2018-06-01

Evaluate usage trends of neural response telemetry (NRT) in cochlear implant centers across the nation and assess reported benefits of intraoperative NRT for pediatric cochlear implant recipients. Survey. All US cochlear implant centers (n = 110). A 15-question multiple-choice survey was distributed electronically to all centers. The survey captured demographic information of all centers, practice patterns surrounding the use of NRT, and the extent to which intraoperative NRT is of benefit. Thirty-two invited participants (29%) completed the survey. A majority of participants reported practicing in an academic center (66%), followed by a hospital setting (19%) and private practice (16%). Seventy-two percent of survey participants reported using NRT for pediatric cochlear implant recipients. Sixty-three percent felt it improved the ability to program at initial activation, and 50% of participants felt that NRT improves satisfaction at initial activation. This study suggests that a majority of surgeons use intraoperative NRT for pediatric cochlear implantation as an additional measure to ensure appropriate electrode placement and improve device activation. Larger studies are needed to better establish the relationship between intraoperative NRT and postoperative outcomes and justify the additional costs associated with intraoperative NRT.

Topics in Modeling of Cochlear Dynamics: Computation, Response and Stability Analysis

NASA Astrophysics Data System (ADS)

Filo, Maurice G.

This thesis touches upon several topics in cochlear modeling. Throughout the literature, mathematical models of the cochlea vary according to the degree of biological realism to be incorporated. This thesis casts the cochlear model as a continuous space-time dynamical system using operator language. This framework encompasses a wider class of cochlear models and makes the dynamics more transparent and easier to analyze before applying any numerical method to discretize space. In fact, several numerical methods are investigated to study the computational efficiency of the finite dimensional realizations in space. Furthermore, we study the effects of the active gain perturbations on the stability of the linearized dynamics. The stability analysis is used to explain possible mechanisms underlying spontaneous otoacoustic emissions and tinnitus. Dynamic Mode Decomposition (DMD) is introduced as a useful tool to analyze the response of nonlinear cochlear models. Cochlear response features are illustrated using DMD which has the advantage of explicitly revealing the spatial modes of vibrations occurring in the Basilar Membrane (BM). Finally, we address the dynamic estimation problem of BM vibrations using Extended Kalman Filters (EKF). Due to the limitations of noninvasive sensing schemes, such algorithms are inevitable to estimate the dynamic behavior of a living cochlea.

Voice gender identification by cochlear implant users: The role of spectral and temporal resolution

NASA Astrophysics Data System (ADS)

Fu, Qian-Jie; Chinchilla, Sherol; Nogaki, Geraldine; Galvin, John J.

2005-09-01

The present study explored the relative contributions of spectral and temporal information to voice gender identification by cochlear implant users and normal-hearing subjects. Cochlear implant listeners were tested using their everyday speech processors, while normal-hearing subjects were tested under speech processing conditions that simulated various degrees of spectral resolution, temporal resolution, and spectral mismatch. Voice gender identification was tested for two talker sets. In Talker Set 1, the mean fundamental frequency values of the male and female talkers differed by 100 Hz while in Talker Set 2, the mean values differed by 10 Hz. Cochlear implant listeners achieved higher levels of performance with Talker Set 1, while performance was significantly reduced for Talker Set 2. For normal-hearing listeners, performance was significantly affected by the spectral resolution, for both Talker Sets. With matched speech, temporal cues contributed to voice gender identification only for Talker Set 1 while spectral mismatch significantly reduced performance for both Talker Sets. The performance of cochlear implant listeners was similar to that of normal-hearing subjects listening to 4-8 spectral channels. The results suggest that, because of the reduced spectral resolution, cochlear implant patients may attend strongly to periodicity cues to distinguish voice gender.

Verbal Working Memory in Children With Cochlear Implants

PubMed Central

Caldwell-Tarr, Amanda; Low, Keri E.; Lowenstein, Joanna H.

2017-01-01

Purpose Verbal working memory in children with cochlear implants and children with normal hearing was examined. Participants Ninety-three fourth graders (47 with normal hearing, 46 with cochlear implants) participated, all of whom were in a longitudinal study and had working memory assessed 2 years earlier. Method A dual-component model of working memory was adopted, and a serial recall task measured storage and processing. Potential predictor variables were phonological awareness, vocabulary knowledge, nonverbal IQ, and several treatment variables. Potential dependent functions were literacy, expressive language, and speech-in-noise recognition. Results Children with cochlear implants showed deficits in storage and processing, similar in size to those at second grade. Predictors of verbal working memory differed across groups: Phonological awareness explained the most variance in children with normal hearing; vocabulary explained the most variance in children with cochlear implants. Treatment variables explained little of the variance. Where potentially dependent functions were concerned, verbal working memory accounted for little variance once the variance explained by other predictors was removed. Conclusions The verbal working memory deficits of children with cochlear implants arise due to signal degradation, which limits their abilities to acquire phonological awareness. That hinders their abilities to store items using a phonological code. PMID:29075747

Social participation of children and adolescents with cochlear implants: a qualitative analysis of parent, teacher, and child interviews.

PubMed

Punch, Renée; Hyde, Merv

2011-01-01

Psychosocial factors, including socioemotional well-being, peer relationships, and social inclusion with hearing and deaf peers, are increasingly becoming a focus of research investigating children with cochlear implants. The study reported here extends the largely quantitative findings of previous research through a qualitative analysis of interviews with parents, teachers, and pediatric cochlear implant users themselves in three eastern states of Australia. We interviewed 24 parents, 15 teachers, and 11 children and adolescents. The findings displayed commonalities across the three groups of participants, indicating positive experiences around the children's psychosocial development with their cochlear implants, but also ongoing difficulties communicating in groups of people and problems related to social skills. Some children had little contact with other deaf children (with or without cochlear implants) despite parents and teachers perceiving such contact beneficial. Children attending schools where there were other deaf children valued friendships with both deaf and hearing peers. Adolescence was a particularly difficult time for some as they struggled with feelings of self-consciousness about their deafness and external cochlear implant equipment and worries around friendships, dating, and their future place in the world. Recommendations for practice and further research are made.

Auditory Speech Perception Tests in Relation to the Coding Strategy in Cochlear Implant.

PubMed

Bazon, Aline Cristine; Mantello, Erika Barioni; Gonçales, Alina Sanches; Isaac, Myriam de Lima; Hyppolito, Miguel Angelo; Reis, Ana Cláudia Mirândola Barbosa

2016-07-01

The objective of the evaluation of auditory perception of cochlear implant users is to determine how the acoustic signal is processed, leading to the recognition and understanding of sound. To investigate the differences in the process of auditory speech perception in individuals with postlingual hearing loss wearing a cochlear implant, using two different speech coding strategies, and to analyze speech perception and handicap perception in relation to the strategy used. This study is prospective cross-sectional cohort study of a descriptive character. We selected ten cochlear implant users that were characterized by hearing threshold by the application of speech perception tests and of the Hearing Handicap Inventory for Adults. There was no significant difference when comparing the variables subject age, age at acquisition of hearing loss, etiology, time of hearing deprivation, time of cochlear implant use and mean hearing threshold with the cochlear implant with the shift in speech coding strategy. There was no relationship between lack of handicap perception and improvement in speech perception in both speech coding strategies used. There was no significant difference between the strategies evaluated and no relation was observed between them and the variables studied.

Effects of a Word-Learning Training on Children With Cochlear Implants

PubMed Central

Lund, Emily

2014-01-01

Preschool children with hearing loss who use cochlear implants demonstrate vocabulary delays when compared to their peers without hearing loss. These delays may be a result of deficient word-learning abilities; children with cochlear implants perform more poorly on rapid word-learning tasks than children with normal hearing. This study explored the malleability of rapid word learning of preschoolers with cochlear implants by evaluating the effects of a word-learning training on rapid word learning. A single-subject, multiple probe design across participants measured the impact of the training on children’s rapid word-learning performance. Participants included 5 preschool children with cochlear implants who had an expressive lexicon of less than 150 words. An investigator guided children to identify, repeat, and learn about unknown sets of words in 2-weekly sessions across 10 weeks. The probe measure, a rapid word-learning task with a different set of words than those taught during training, was collected in the baseline, training, and maintenance conditions. All participants improved their receptive rapid word-learning performance in the training condition. The functional relation indicates that the receptive rapid word-learning performance of children with cochlear implants is malleable. PMID:23981321

The cochlear implant as a tinnitus treatment.

PubMed

Vallés-Varela, Héctor; Royo-López, Juan; Carmen-Sampériz, Luis; Sebastián-Cortés, José M; Alfonso-Collado, Ignacio

2013-01-01

Tinnitus is a symptom of high prevalence in patients with cochlear pathology. We studied the evolution of tinnitus in patients undergoing unilateral cochlear implantation for treatment of profound hearing loss. This was a longitudinal, retrospective study of patients that underwent unilateral cochlear implantation and who had bilateral tinnitus. Tinnitus was assessed quantitatively and qualitatively before surgery and at 6 and 12 months after surgery. We evaluated 20 patients that underwent unilateral cochlear implantation with a Nucleus(®) CI24RE Contour Advance™ electrode device. During the periods in which the device was in operation, improvement or disappearance of tinnitus was evidenced in the ipsilateral ear in 65% of patients, and in the contralateral ear, in 50%. In periods in which the device was disconnected, improvement or disappearance of tinnitus was found in the ipsilateral ear in 50% of patients, and in the ear contralateral to the implant in 45% of the patients. In 10% of the patients, a new tinnitus appeared in the ipsilateral ear. The patients with profound hearing loss and bilateral tinnitus treated with unilateral cochlear implantation improved in a high percentage of cases, in the ipsilateral ear and in the contralateral ear. Copyright © 2012 Elsevier España, S.L. All rights reserved.

Cochlear implants and spoken language processing abilities: review and assessment of the literature.

PubMed

Peterson, Nathaniel R; Pisoni, David B; Miyamoto, Richard T

2010-01-01

Cochlear implants (CIs) process sounds electronically and then transmit electric stimulation to the cochlea of individuals with sensorineural deafness, restoring some sensation of auditory perception. Many congenitally deaf CI recipients achieve a high degree of accuracy in speech perception and develop near-normal language skills. Post-lingually deafened implant recipients often regain the ability to understand and use spoken language with or without the aid of visual input (i.e. lip reading). However, there is wide variation in individual outcomes following cochlear implantation, and some CI recipients never develop useable speech and oral language skills. The causes of this enormous variation in outcomes are only partly understood at the present time. The variables most strongly associated with language outcomes are age at implantation and mode of communication in rehabilitation. Thus, some of the more important factors determining success of cochlear implantation are broadly related to neural plasticity that appears to be transiently present in deaf individuals. In this article we review the expected outcomes of cochlear implantation, potential predictors of those outcomes, the basic science regarding critical and sensitive periods, and several new research directions in the field of cochlear implantation.

Clinical outcomes of scala vestibuli cochlear implantation in children with partial labyrinthine ossification.

PubMed

Lin, Yung-Song

2009-03-01

Cochlear implantation via the scala vestibuli is a viable approach in those with ossification in the scala tympani. With extended cochlear implant experience, there is no significant difference in the mapping parameters and auditory performance between those implanted via scala vestibuli and via scala tympani. To assess the clinical outcomes of cochlear implantation via scala vestibuli. In a cohort follow-up study, 11 prelingually deafened children who received cochlear implantation between age 3 and 10 years through the scala vestibuli served as participants. The mapping parameters (i.e. comfortable level (C), threshold level (T), dynamic range) and auditory performance of each participant were evaluated following initial cochlear implant stimulation, then at 3 month intervals for 2 years, then semi-annually. The follow-up period lasted for 9 years 9 months on average, with a minimum of 8 years 3 months. The clinical results of the mapping parameters and auditory performance of children implanted via the scala vestibuli were comparative to those who were implanted via the scala tympani. No balance problem was reported by any of these patients. One child exhibited residual low frequency hearing after implantation.

Current Research with Cochlear Implants at Arizona State University

PubMed Central

Dorman, Michael F.; Spahr, Anthony; Gifford, Rene H.; Cook, Sarah; Zhang, Ting; Loiselle, Louise; Yost, William; Cardy, Lara; Whittingham, JoAnne; Schramm, David

2013-01-01

In this article we review, and discuss the clinical implications of, five projects currently underway in the Cochlear Implant Laboratory at Arizona State University. The projects are (1) norming the AzBio sentence test, (2) comparing the performance of bilateral and bimodal cochlear implant (CI) patients in realistic listening environments, (3) accounting for the benefit provided to bimodal patients by low-frequency acoustic stimulation, (4) assessing localization by bilateral hearing aid patients and the implications of that work for hearing preservation patients, and (5) studying heart rate variability as a possible measure for quantifying the stress of listening via an implant. The long-term goals of the laboratory are to improve the performance of patients fit with cochlear implants and to understand the mechanisms, physiological or electronic, that underlie changes in performance. We began our work with cochlear implant patients in the mid-1980s and received our first grant from the National Institutes of Health (NIH) for work with implanted patients in 1989. Since that date our work with cochlear implant patients has been funded continuously by the NIH. In this report we describe some of the research currently being conducted in our laboratory. PMID:22668760

The importance of electrically evoked stapedial reflex in cochlear implant.

PubMed

Andrade, Kelly Cristina Lira de; Leal, Mariana de Carvalho; Muniz, Lilian Ferreira; Menezes, Pedro de Lemos; Albuquerque, Katia Maria Gomes de; Carnaúba, Aline Tenório Lins

2014-01-01

The most important stage in fitting a cochlear implant is the identification of its dynamic range. The use of objective measures, in particular the electrically elicited stapedius reflex, may provide suitable assistence for initial fitting of cochlear implant, especially in children or adult with multiple disorders, because they provide specific values that serve as the basis of early cochlear implant programming. Verify through a review the use of the electrically elicited stapedius reflex threshold during the activation and mapping process of cochlear implant. Bibliographical search on the Pubmed and Bireme plataforms, and also on Medline, LILACS and SciELO databases, with standard searches until September 2012, using specific keywords. For the selection and evaluation of scientific studies found in the search, criterias have been established, considering the following aspects: author, year/location, grade of recommendation/level of evidence, purpose, sample, age, mean age in years, evaluative testing, results and conclusion. Among 7,304 articles found, 7,080 were excluded from the title, 152 from the abstract, 17 from the article reading, 43 were repeated and 12 were selected for the study. The electrically elicited stapedius reflex may support when programming the cochlear implant, especially in patients with inconsistent responses.

The relationship between loudness intensity functions and the click-ABR wave V latency.

PubMed

Serpanos, Y C; O'Malley, H; Gravel, J S

1997-10-01

To assess the relationship of loudness growth and the click-evoked auditory brain stem response (ABR) wave V latency-intensity function (LIF) in listeners with normal hearing or cochlear hearing loss. The effect of hearing loss configuration on the intensity functions was also examined. Behavioral and electrophysiological intensity functions were obtained using click stimuli of comparable intensities in listeners with normal hearing (Group I; n = 10), and cochlear hearing loss of flat (Group II; n = 10) or sloping (Group III; n = 10) configurations. Individual intensity functions were obtained from measures of loudness growth using the psychophysical methods of absolute magnitude estimation and production of loudness (geometrically averaged to provide the measured loudness function), and from the wave V latency measures of the ABR. Slope analyses for the behavioral and electrophysiological intensity functions were separately performed by group. The loudness growth functions for the groups with cochlear hearing loss approximated the normal function at high intensities, with overall slope values consistent with those reported from previous psychophysical research. The ABR wave V LIF for the group with a flat configuration of cochlear hearing loss approximated the normal function at high intensities, and was displaced parallel to the normal function for the group with sloping configuration. The relationship between the behavioral and electrophysiological intensity functions was examined at individual intensities across the range of the functions for each subject. A significant relationship was obtained between loudness and the ABR wave V LIFs for the groups with normal hearing and flat configuration of cochlear hearing loss; the association was not significant (p = 0.10) for the group with a sloping configuration of cochlear hearing loss. The results of this study established a relationship between loudness and the ABR wave V latency for listeners with normal hearing, and flat cochlear hearing loss. In listeners with a sloping configuration of cochlear hearing loss, the relationship was not significant. This suggests that the click-evoked ABR may be used to estimate loudness growth at least for individuals with normal hearing and those with a flat configuration of cochlear hearing loss. Predictive equations were derived to estimate loudness growth for these groups. The use of frequency-specific stimuli may provide more precise information on the nature of the relationship between loudness growth and the ABR wave V latency, particularly for listeners with sloping configurations of cochlear hearing loss.

Electrophysiological evidence for altered visual, but not auditory, selective attention in adolescent cochlear implant users.

PubMed

Harris, Jill; Kamke, Marc R

2014-11-01

Selective attention fundamentally alters sensory perception, but little is known about the functioning of attention in individuals who use a cochlear implant. This study aimed to investigate visual and auditory attention in adolescent cochlear implant users. Event related potentials were used to investigate the influence of attention on visual and auditory evoked potentials in six cochlear implant users and age-matched normally-hearing children. Participants were presented with streams of alternating visual and auditory stimuli in an oddball paradigm: each modality contained frequently presented 'standard' and infrequent 'deviant' stimuli. Across different blocks attention was directed to either the visual or auditory modality. For the visual stimuli attention boosted the early N1 potential, but this effect was larger for cochlear implant users. Attention was also associated with a later P3 component for the visual deviant stimulus, but there was no difference between groups in the later attention effects. For the auditory stimuli, attention was associated with a decrease in N1 latency as well as a robust P3 for the deviant tone. Importantly, there was no difference between groups in these auditory attention effects. The results suggest that basic mechanisms of auditory attention are largely normal in children who are proficient cochlear implant users, but that visual attention may be altered. Ultimately, a better understanding of how selective attention influences sensory perception in cochlear implant users will be important for optimising habilitation strategies. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Sequential Bilateral Cochlear Implantation in a Patient with Bilateral Meniere’s Disease

PubMed Central

Holden, Laura K.; Neely, J. Gail; Gotter, Brenda D.; Mispagel, Karen M.; Firszt, Jill B.

2012-01-01

This case study describes a 45 year old female with bilateral, profound sensorineural hearing loss due to Meniere’s disease. She received her first cochlear implant in the right ear in 2008 and the second cochlear implant in the left ear in 2010. The case study examines the enhancement to speech recognition, particularly in noise, provided by bilateral cochlear implants. Speech recognition tests were administered prior to obtaining the second implant and at a number of test intervals following activation of the second device. Speech recognition in quiet and noise as well as localization abilities were assessed in several conditions to determine bilateral benefit and performance differences between ears. The results of the speech recognition testing indicated a substantial improvement in the patient’s ability to understand speech in noise and her ability to localize sound when using bilateral cochlear implants compared to using a unilateral implant or an implant and a hearing aid. In addition, the patient reported considerable improvement in her ability to communicate in daily life when using bilateral implants versus a unilateral implant. This case suggests that cochlear implantation is a viable option for patients who have lost their hearing to Meniere’s disease even when a number of medical treatments and surgical interventions have been performed to control vertigo. In the case presented, bilateral cochlear implantation was necessary for this patient to communicate successfully at home and at work. PMID:22463939

Electrical resistivity measurements in the mammalian cochlea after neural degeneration.

PubMed

Micco, Alan G; Richter, Claus-Peter

2006-08-01

In the present series of experiments, the effect of neural degeneration on the cochlear structure electrical resistivities was evaluated to test if it alters the current flow in the cochlea and if increased current levels are needed to stimulate the impaired cochlea. In cochlear implants, frequency information is encoded in part by stimulating discrete populations of spiral ganglion cells along the cochlea. However, electrical properties of the cochlear structures result in shunting of the current away from the auditory neurons. This consumes energy, makes cochlear implants less efficient, and drastically reduces battery life. Models of the electrically stimulated cochlea serve to make predictions on current paths using modified and improved cochlear implant electrodes. However, one of the model's shortcomings is that most of the values for tissue impedances are not direct measurements. They are derived from bulk impedance measurements, which are fitted to lumped-element models. The four-electrode reflection-coefficient technique was used to measure resistivities in the gerbil cochlea. In vivo and in vitro (the hemicochlea) models were used. Measurements were made in normal and in deafened animals. Cochlear damage was induced by neomycin injection into the animals' middle ears. Neural degeneration was allowed to occur over 2 months before performing the measurements in the deafened animals. The resistivity values in deafened animals were smaller than in the normal-hearing animals, thus altering the current flow within the cochlea. Resistivity changes and subsequent changes in current path should be considered in future designs of cochlear implants.

Electric charge requirements of pediatric cochlear implant recipients enrolled in the Childhood Development After Cochlear Implantation study.

PubMed

Zwolan, Teresa A; O'Sullivan, Mary Beth; Fink, Nancy E; Niparko, John K

2008-02-01

To evaluate mapping characteristics of children with cochlear implants who are enrolled in the Childhood Development After Cochlear Implantation (CDACI) multicenter study. Longitudinal evaluation during 24 months of speech processor maps of children with cochlear implants prospectively enrolled in the study. Six tertiary referral centers. One hundred eighty-eight children enrolled in the CDACI study who were 5 years old or younger at the time of enrollment. Of these children, 184 received unilateral implants, and 4 received simultaneous bilateral implants. Children attended regular mapping sessions at their implant clinic as part of the study protocol. Maps were examined for each subject at 4 different time intervals: at device activation and 6, 12, and 24 months postactivation. Mean C/M levels (in charge per phase) were compared for 4 different time intervals, for 3 different devices, for 6 different implant centers, and for children with normal and abnormal cochleae. All 3 types of implant devices demonstrate significant increases in C/M levels between device activation and the 24-month appointment. Significant differences in mean C/M levels were noted between devices. Children with cochlear anomalies demonstrate significantly greater C/M levels than children with normal cochleae. The CDACI study has enabled us to evaluate the mapping characteristics of pediatric patients who use 3 different devices and were implanted at a variety of implant centers. Analysis of such data enables us to better understand the mapping characteristics of children with cochlear implants.

Reissner's membrane and the spiral ligament in normal rats and those treated with ethacrynic acid

NASA Technical Reports Server (NTRS)

Ross, M. D.

1981-01-01

A description is presented of recent ultrastructural findings in Reissner's membrane and the spiral ligament in rats treated daily with ethacrynic acid during the 2nd and 3rd weeks of postnatal life, a period of final maturation of the inner ear and its fluids. A distension of Reissner's membrane in every cochlear turn, indicative of mild endolymphatic hydrops, was found to occur in animals that received a higher dose of ethacrynic acid. Ultrastructurally, the cytoplasm of the epithelial cells of Reissner's membrane showed increased electron density after treatment with ethacrynic acid. This increase was most pronounced in animals treated with a greater quantity of the drug. The epithelial cells had similar ultracellular features throughout except that the cells were much thinner in the region of maximal distension.

Speech Perception for Adults Who Use Hearing Aids in Conjunction with Cochlear Implants in Opposite Ears

ERIC Educational Resources Information Center

Mok, Mansze; Grayden, David; Dowell, Richard C.; Lawrence, David

2006-01-01

This study aimed to (a) investigate the effect of using a hearing aid in conjunction with a cochlear implant in opposite ears on speech perception in quiet and in noise, (b) identify the speech information obtained from a hearing aid that is additive to the information obtained from a cochlear implant, and (c) explore the relationship between…

Sirviendo a los estudiantes sordos que tienen Los implantes cocleares. Hoja de consejos de PEPNet (Serving Deaf Students Who Have Cochlear Implants. PEPNet Tipsheet)

ERIC Educational Resources Information Center

Clark, Catherine

2010-01-01

This version of "Serving Deaf Students Who Have Cochlear Implants. PEPNet Tipsheet," written in Spanish, describes how cochlear implants (CIs) work. CIs are complex electronic devices surgically implanted under the skin behind the ear. These devices utilize electrodes placed in the inner ear (the cochlea) to stimulate the auditory nerve of…

Sensitivity in Interactions between Hearing Mothers and their Toddlers with Hearing Loss: The Effect of Cochlear Implantation

ERIC Educational Resources Information Center

Bakar, Zaharah Abu; Brown, P. Margaret; Remine, Maria D.

2010-01-01

This study investigated the potential effects of cochlear implantation and age at implantation on maternal interactional sensitivity. Three groups of dyads were studied at two points over 1 year. The hearing aid (HA) group wore hearing aids throughout the study, the early cochlear implanted (ECI) group were implanted prior to 22 months of age, and…

The Relation Between Child Versus Parent Report of Chronic Fatigue and Language/Literacy Skills in School-Age Children with Cochlear Implants.

PubMed

Werfel, Krystal L; Hendricks, Alison Eisel

2016-01-01

Preliminary evidence suggests that children with hearing loss experience elevated levels of chronic fatigue compared with children with normal hearing. Chronic fatigue is associated with decreased academic performance in many clinical populations. Children with cochlear implants as a group exhibit deficits in language and literacy skills; however, the relation between chronic fatigue and language and literacy skills for children with cochlear implants is unclear. The purpose of this study was to explore subjective ratings of chronic fatigue by children with cochlear implants and their parents, as well as the relation between chronic fatigue and language and literacy skills in this population. Nineteen children with cochlear implants in grades 3 to 6 and one of their parents separately completed a subjective chronic fatigue scale, on which they rated how much the child experienced physical, sleep/rest, and cognitive fatigue over the past month. In addition, children completed an assessment battery that included measures of speech perception, oral language, word reading, and spelling. Children and parents reported different levels of chronic child physical and sleep/rest fatigue. In both cases, parents reported significantly less fatigue than did children. Children and parents did not report different levels of chronic child cognitive fatigue. Child report of physical fatigue was related to speech perception, language, reading, and spelling. Child report of sleep/rest and cognitive fatigue was related to speech perception and language but not to reading or spelling. Parent report of child fatigue was not related to children's language and literacy skills. Taken as a whole, results suggested that parents under-estimate the fatigue experienced by children with cochlear implants. Child report of physical fatigue was robustly related to language and literacy skills. Children with cochlear implants are likely more accurate at reporting physical fatigue than cognitive fatigue. Clinical practice should take fatigue into account when developing treatment plans for children with cochlear implants, and research should continue to develop a comprehensive model of fatigue in children with cochlear implants.

The role of young, recently disturbed upland hardwood forest as high quality food patches

Treesearch

Cathryn H. Greenberg; Roger W. Perry; Craig A. Harper; Douglas J. Levey; John M. McCord

2011-01-01

Young (1-10 year post-disturbance) upland hardwood forests function as high-quality food patches by providing abundant fruit, and nutritious foliage and flowers that attract pollinating and foliar arthropods and support high populations of small mammals that, in turn, are prey for numerous vertebrate predators. Reductions in basal area increase light penetration to the...

Protective effect of hexane and ethanol extract of piper longum L. On gentamicin-induced hair cell loss in neonatal cultures.

PubMed

Yadav, Mukesh Kumar; Choi, June; Song, Jae-Jun

2014-03-01

Gentamicin (GM) is a commonly used aminoglycoside antibiotic that generates free oxygen radicals within the inner ear, which can cause vestibulo-cochlear toxicity and permanent damage to the sensory hair cells and neurons. Piper longum L. (PL) is a well-known spice and traditional medicine in Asia and Pacific islands, which has been reported to exhibit a wide spectrum of activity, including antioxidant activity. In this study, we evaluated the effect of hexane:ethanol (2:8) PL extract (subfraction of PL [SPL] extract) on GM-induced hair cell loss in basal, middle and apical regions in a neonatal cochlea cultures. The protective effects of SPL extract were measured by phalloidin staining of cultures from postnatal day 2-3 mice with GM-induced hair cell loss. The anti-apoptosis activity of SPL extract was measured using double labeling by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and myosin-7a staining. The radical-scavenging activity of SPL extract was assessed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. SPL extract at a concentration of 1 µg/mL significantly inhibited GM-induced hair cell loss at basal and middle region of cochlea, while 5 µg/mL was effective against apical region hair cell loss. The protective effect of SPL extract was concentration dependent and hair cells retained their stereocilia in explants treated with SPL extract prior to treatment with 0.3 mM GM. SPL extract decreased GM-induced apoptosis of hair cells as assessed by TUNEL staining. The outer hair and inner hair counts were not decreased in SPL extract treated groups in compare to GM treated explants. Additionally, SPL extract showed concentration dependent radical scavenging activity in a DPPH assay. An anti-apoptosis effect and potent radical scavenger activity of SPL extract protects from GM-induced hair cell loss at basal, middle and apical regions in neonatal cochlea cultures.

Relationship between Contrast Enhancement of the Perivascular Space in the Basal Ganglia and Endolymphatic Volume Ratio.

PubMed

Ohashi, Toshio; Naganawa, Shinji; Katagiri, Toshio; Kuno, Kayao

2018-01-10

We routinely obtain the endolymphatic hydrops (EH) image using heavily T 2 -weighted three dimensional-fluid attenuated inversion recovery (hT 2 w-3D-FLAIR) imaging at 4 hours after intravenous administration of a single-dose of gadolinium-based contrast media (IV-SD-GBCM). While repeating the examination, we speculated that the contrast enhancement of the perivascular space (PVS) in the basal ganglia might be related to the degree of EH. Therefore, the purpose of this study was to investigate the relationship between the endolymphatic volume ratio (%EL volume ) and the signal intensity of the PVS (SI-PVS). In 20 patients with a suspicion of EH, a heavily T 2 -weighted 3D-turbo spin echo sequence for MR cisternography (MRC) and an hT 2 w-3D-FLAIR as a positive perilymph image (PPI) were obtained at 4 hours after IV-SD-GBCM. The %EL volume of the cochlea and the vestibule were measured on the previously reported HYDROPS2-Mi2 image. The PVS in the basal ganglia was segmented on MRC using a region-growing method. The PVS regions were copied and pasted onto the PPI, and the SI-PVS was measured. The larger value of the right and the left ears was employed as the %EL volume , and the weighted average of both sides was employed as the SI-PVS. The correlation between the %EL volume and the SI-PVS was evaluated. There was a strong negative linear correlation between the %EL volume of the cochlea and the SI-PVS (r = -0.743, P < 0.001); however, there was no significant correlation between the %EL volume of the vestibule and the SI-PVS (r = -0.267, P = 0.256). There was a strong negative correlation between the cochlear %EL volume and the SI-PVS. Contrast enhancement of PVS might be a biomarker of EH.

Relationship between Contrast Enhancement of the Perivascular Space in the Basal Ganglia and Endolymphatic Volume Ratio

PubMed Central

Ohashi, Toshio; Naganawa, Shinji; Katagiri, Toshio; Kuno, Kayao

2018-01-01

Purpose: We routinely obtain the endolymphatic hydrops (EH) image using heavily T2-weighted three dimensional-fluid attenuated inversion recovery (hT2w-3D-FLAIR) imaging at 4 hours after intravenous administration of a single-dose of gadolinium-based contrast media (IV-SD-GBCM). While repeating the examination, we speculated that the contrast enhancement of the perivascular space (PVS) in the basal ganglia might be related to the degree of EH. Therefore, the purpose of this study was to investigate the relationship between the endolymphatic volume ratio (%ELvolume) and the signal intensity of the PVS (SI-PVS). Materials and Methods: In 20 patients with a suspicion of EH, a heavily T2-weighted 3D-turbo spin echo sequence for MR cisternography (MRC) and an hT2w-3D-FLAIR as a positive perilymph image (PPI) were obtained at 4 hours after IV-SD-GBCM. The %ELvolume of the cochlea and the vestibule were measured on the previously reported HYDROPS2-Mi2 image. The PVS in the basal ganglia was segmented on MRC using a region-growing method. The PVS regions were copied and pasted onto the PPI, and the SI-PVS was measured. The larger value of the right and the left ears was employed as the %ELvolume, and the weighted average of both sides was employed as the SI-PVS. The correlation between the %ELvolume and the SI-PVS was evaluated. Result: There was a strong negative linear correlation between the %ELvolume of the cochlea and the SI-PVS (r = −0.743, P < 0.001); however, there was no significant correlation between the %ELvolume of the vestibule and the SI-PVS (r = −0.267, P = 0.256). Conclusion: There was a strong negative correlation between the cochlear %ELvolume and the SI-PVS. Contrast enhancement of PVS might be a biomarker of EH. PMID:28592709

Subcortical amplitude modulation encoding deficits suggest evidence of cochlear synaptopathy in normal-hearing 18-19 year olds with higher lifetime noise exposure.

PubMed

Paul, Brandon T; Waheed, Sajal; Bruce, Ian C; Roberts, Larry E

2017-11-01

Noise exposure and aging can damage cochlear synapses required for suprathreshold listening, even when cochlear structures needed for hearing at threshold remain unaffected. To control for effects of aging, behavioral amplitude modulation (AM) detection and subcortical envelope following responses (EFRs) to AM tones in 25 age-restricted (18-19 years) participants with normal thresholds, but different self-reported noise exposure histories were studied. Participants with more noise exposure had smaller EFRs and tended to have poorer AM detection than less-exposed individuals. Simulations of the EFR using a well-established cochlear model were consistent with more synaptopathy in participants reporting greater noise exposure.

Is the Cochlear Amplifier a Fluid Pump?

NASA Astrophysics Data System (ADS)

Karavitaki, K. D.; Mountain, D. C.

2003-02-01

We have visualized and quantified the effects of electrically evoked motility of outer hair cells (OHCs) within the organ of Corti using an excised cochlear preparation. We found that OHC motility induces oscillatory fluid flow in the tunnel of Corti (TC) and this flow is present at physiologically relevant frequencies. We also show, using a simple one-dimensional hydromechanical model of the TC, that a fluid wave within the tunnel can travel without significant attenuation for distances larger than the wavelength of the cochlear traveling wave. These results in combination with a recent hypothesis that fluid flow within the tunnel is necessary for cochlear amplification suggest that the function of the OHCs is to act as a fluid pump.

Relating the variability of tone-burst otoacoustic emission and auditory brainstem response latencies to the underlying cochlear mechanics

NASA Astrophysics Data System (ADS)

Verhulst, Sarah; Shera, Christopher A.

2015-12-01

Forward and reverse cochlear latency and its relation to the frequency tuning of the auditory filters can be assessed using tone bursts (TBs). Otoacoustic emissions (TBOAEs) estimate the cochlear roundtrip time, while auditory brainstem responses (ABRs) to the same stimuli aim at measuring the auditory filter buildup time. Latency ratios are generally close to two and controversy exists about the relationship of this ratio to cochlear mechanics. We explored why the two methods provide different estimates of filter buildup time, and ratios with large inter-subject variability, using a time-domain model for OAEs and ABRs. We compared latencies for twenty models, in which all parameters but the cochlear irregularities responsible for reflection-source OAEs were identical, and found that TBOAE latencies were much more variable than ABR latencies. Multiple reflection-sources generated within the evoking stimulus bandwidth were found to shape the TBOAE envelope and complicate the interpretation of TBOAE latency and TBOAE/ABR ratios in terms of auditory filter tuning.

Long latency auditory evoked potentials in children with cochlear implants: systematic review.

PubMed

Silva, Liliane Aparecida Fagundes; Couto, Maria Inês Vieira; Matas, Carla Gentile; Carvalho, Ana Claudia Martinho de

2013-11-25

The aim of this study was to analyze the findings on Cortical Auditory Evoked Potentials in children with cochlear implant through a systematic literature review. After formulation of research question and search of studies in four data bases with the following descriptors: electrophysiology (eletrofisiologia), cochlear implantation (implante coclear), child (criança), neuronal plasticity (plasticidade neuronal) and audiology (audiologia), were selected articles (original and complete) published between 2002 and 2013 in Brazilian Portuguese or English. A total of 208 studies were found; however, only 13 contemplated the established criteria and were further analyzed; was made data extraction for analysis of methodology and content of the studies. The results described suggest rapid changes in P1 component of Cortical Auditory Evoked Potentials in children with cochlear implants. Although there are few studies on the theme, cochlear implant has been shown to produce effective changes in central auditory path ways especially in children implanted before 3 years and 6 months of age.

Corticofugal modulation of peripheral auditory responses

PubMed Central

Terreros, Gonzalo; Delano, Paul H.

2015-01-01

The auditory efferent system originates in the auditory cortex and projects to the medial geniculate body (MGB), inferior colliculus (IC), cochlear nucleus (CN) and superior olivary complex (SOC) reaching the cochlea through olivocochlear (OC) fibers. This unique neuronal network is organized in several afferent-efferent feedback loops including: the (i) colliculo-thalamic-cortico-collicular; (ii) cortico-(collicular)-OC; and (iii) cortico-(collicular)-CN pathways. Recent experiments demonstrate that blocking ongoing auditory-cortex activity with pharmacological and physical methods modulates the amplitude of cochlear potentials. In addition, auditory-cortex microstimulation independently modulates cochlear sensitivity and the strength of the OC reflex. In this mini-review, anatomical and physiological evidence supporting the presence of a functional efferent network from the auditory cortex to the cochlear receptor is presented. Special emphasis is given to the corticofugal effects on initial auditory processing, that is, on CN, auditory nerve and cochlear responses. A working model of three parallel pathways from the auditory cortex to the cochlea and auditory nerve is proposed. PMID:26483647

Technical devices for hearing-impaired individuals: cochlear implants and brain stem implants - developments of the last decade

PubMed Central

Müller, Joachim

2005-01-01

Over the past two decades, the fascinating possibilities of cochlear implants for congenitally deaf or deafened children and adults developed tremendously and created a rapidly developing interdisciplinary research field. The main advancements of cochlear implantation in the past decade are marked by significant improvement of hearing and speech understanding in CI users. These improvements are attributed to the enhancement of speech coding strategies. The Implantation of more (and increasingly younger) children as well as the possibilities of the restoration of binaural hearing abilities with cochlear implants reflect the high standards reached by this development. Despite this progress, modern cochlear implants do not yet enable normal speech understanding, not even for the best patients. In particular speech understanding in noise remains problematic [1]. Until the mid 1990ies research concentrated on unilateral implantation. Remarkable and effective improvements have been made with bilateral implantation since 1996. Nowadays an increasing numbers of patients enjoy these benefits. PMID:22073052

Technical devices for hearing-impaired individuals: cochlear implants and brain stem implants - developments of the last decade.

PubMed

Müller, Joachim

2005-01-01

Over the past two decades, the fascinating possibilities of cochlear implants for congenitally deaf or deafened children and adults developed tremendously and created a rapidly developing interdisciplinary research field.The main advancements of cochlear implantation in the past decade are marked by significant improvement of hearing and speech understanding in CI users. These improvements are attributed to the enhancement of speech coding strategies.The Implantation of more (and increasingly younger) children as well as the possibilities of the restoration of binaural hearing abilities with cochlear implants reflect the high standards reached by this development. Despite this progress, modern cochlear implants do not yet enable normal speech understanding, not even for the best patients. In particular speech understanding in noise remains problematic [1]. Until the mid 1990ies research concentrated on unilateral implantation. Remarkable and effective improvements have been made with bilateral implantation since 1996. Nowadays an increasing numbers of patients enjoy these benefits.

A software tool for analyzing multichannel cochlear implant signals.

PubMed

Lai, Wai Kong; Bögli, Hans; Dillier, Norbert

2003-10-01

A useful and convenient means to analyze the radio frequency (RF) signals being sent by a speech processor to a cochlear implant would be to actually capture and display them with appropriate software. This is particularly useful for development or diagnostic purposes. sCILab (Swiss Cochlear Implant Laboratory) is such a PC-based software tool intended for the Nucleus family of Multichannel Cochlear Implants. Its graphical user interface provides a convenient and intuitive means for visualizing and analyzing the signals encoding speech information. Both numerical and graphic displays are available for detailed examination of the captured CI signals, as well as an acoustic simulation of these CI signals. sCILab has been used in the design and verification of new speech coding strategies, and has also been applied as an analytical tool in studies of how different parameter settings of existing speech coding strategies affect speech perception. As a diagnostic tool, it is also useful for troubleshooting problems with the external equipment of the cochlear implant systems.

A phone-assistive device based on Bluetooth technology for cochlear implant users.

PubMed

Qian, Haifeng; Loizou, Philipos C; Dorman, Michael F

2003-09-01

Hearing-impaired people, and particularly hearing-aid and cochlear-implant users, often have difficulty communicating over the telephone. The intelligibility of telephone speech is considerably lower than the intelligibility of face-to-face speech. This is partly because of lack of visual cues, limited telephone bandwidth, and background noise. In addition, cellphones may cause interference with the hearing aid or cochlear implant. To address these problems that hearing-impaired people experience with telephones, this paper proposes a wireless phone adapter that can be used to route the audio signal directly to the hearing aid or cochlear implant processor. This adapter is based on Bluetooth technology. The favorable features of this new wireless technology make the adapter superior to traditional assistive listening devices. A hardware prototype was built and software programs were written to implement the headset profile in the Bluetooth specification. Three cochlear implant users were tested with the proposed phone-adapter and reported good speech quality.

Cochlear implantation in Waardenburg syndrome: The Indian scenario.

PubMed

Deka, Ramesh Chandra; Sikka, Kapil; Chaturvedy, Gaurav; Singh, Chirom Amit; Venkat Karthikeyan, C; Kumar, Rakesh; Agarwal, Shivani

2010-10-01

Children with Waardenburg syndrome (WS) exhibiting normal inner ear anatomy, like those included in our cohort, derive significant benefit from cochlear implantation and results are comparable to those reported for the general population of implanted children. The patient population of WS accounts for approximately 2% of congenitally deaf children. The purpose of this retrospective case review was to describe the outcomes for those children with WS who have undergone cochlear implantation. On retrospective chart review, there were four cases with WS who underwent cochlear implantation. These cases were assessed for age at implantation, clinical and radiological features, operative and perioperative course, and performance outcomes. Auditory perception and speech production ability were evaluated using categories of auditory performance (CAP), meaningful auditory integration scales (MAIS), and speech intelligibility rating (SIR) during the follow-up period. In this group of children with WS, with a minimum follow-up of 12 months, the CAP score ranged from 3 to 5, MAIS from 25 to 30, and SIR was 3. These scores are comparable with those of other cochlear implantees.

Libyan cochlear implant programme: achievements, difficulties, and future goals

PubMed Central

Salamat, Ali; Esriti, Anwer; Ehtuish, Asia; El-Ogbi, Samya

2011-01-01

Cochlear implantation has become established worldwide as a safe and effective method of auditory rehabilitation of selected severely and profound deaf children and adults. Over 100,000 patients have received cochlear implants worldwide with the paediatric population proving to be the main beneficiaries. The Libyan cochlear implant programme was set up in 2004. Data relating to the patients who received cochlear implantation at Tripoli Medical Centre between October 2007 and February 2010 were analysed. Implant operations were performed on 37 patients. All patients received Med-El SONATATI100 devices. Thirty-four (91.9%) of these patients were children, whilst three (8.1%) were adults. Combined, congenital hearing loss (56.8%) and perinatal/neonatal (29.7%) were the two main aetiological factors in children. Seventeen patients (45.9%) had a positive family history of deafness. Sixteen patients (43.2%) were born to blood-related parents. The overall rate of minor and major complications was 16.2%, which is comparable to previous studies. PMID:21694783

Libyan cochlear implant programme: achievements, difficulties, and future goals.

PubMed

Salamat, Ali; Esriti, Anwer; Ehtuish, Asia; El-Ogbi, Samya

2011-01-01

Cochlear implantation has become established worldwide as a safe and effective method of auditory rehabilitation of selected severely and profound deaf children and adults. Over 100,000 patients have received cochlear implants worldwide with the paediatric population proving to be the main beneficiaries. The Libyan cochlear implant programme was set up in 2004. Data relating to the patients who received cochlear implantation at Tripoli Medical Centre between October 2007 and February 2010 were analysed. Implant operations were performed on 37 patients. All patients received Med-El SONATA(TI) (100) devices. Thirty-four (91.9%) of these patients were children, whilst three (8.1%) were adults. Combined, congenital hearing loss (56.8%) and perinatal/neonatal (29.7%) were the two main aetiological factors in children. Seventeen patients (45.9%) had a positive family history of deafness. Sixteen patients (43.2%) were born to blood-related parents. The overall rate of minor and major complications was 16.2%, which is comparable to previous studies.

Auditory Spatial Perception: Auditory Localization

DTIC Science & Technology

2012-05-01

cochlear nucleus, TB – trapezoid body, SOC – superior olivary complex, LL – lateral lemniscus, IC – inferior colliculus. Adapted from Aharonson and...Figure 5. Auditory pathways in the central nervous system. LE – left ear, RE – right ear, AN – auditory nerve, CN – cochlear nucleus, TB...fibers leaving the left and right inner ear connect directly to the synaptic inputs of the cochlear nucleus (CN) on the same (ipsilateral) side of

Low Level Chemical Toxicity: Relevance to Chemical Agent Defense

DTIC Science & Technology

2005-07-01

elevation in stress hormones in the blood serum. Electron microscropy indicated no damage to cochlear tissues of the ear (not shown). At the...neural activity occurring primarily in the cochlear nucleus of the brainstem auditory pathway. Peak II is usually the last major peak to disappear...IV). Peak II is generally the strongest peak and is regarded as a putative indicator of neural activity occurring primarily in the cochlear nucleus

Sex Difference in Susceptibility and Resistance to Noise-Induced Hearing Loss in Chinchillas

DTIC Science & Technology

2000-10-01

Estradiol assays Blood samples were collected from deeply anesthetized chinchillas prior to cochlear histology. The blood samples were centrifuged to...pattern of hearing loss and cochlear damage for male and female chinchillas Gender differences have been reported in susceptibility to NIHL, both...Given the results of physiological testing (IC-EVPs and CDPs), the results of cochlear histology were somewhat surprising (see McFadden et al., 1999