Science.gov

Sample records for fully implantable stimulator

  1. A fully implantable rodent neural stimulator

    NASA Astrophysics Data System (ADS)

    Perry, D. W. J.; Grayden, D. B.; Shepherd, R. K.; Fallon, J. B.

    2012-02-01

    The ability to electrically stimulate neural and other excitable tissues in behaving experimental animals is invaluable for both the development of neural prostheses and basic neurological research. We developed a fully implantable neural stimulator that is able to deliver two channels of intra-cochlear electrical stimulation in the rat. It is powered via a novel omni-directional inductive link and includes an on-board microcontroller with integrated radio link, programmable current sources and switching circuitry to generate charge-balanced biphasic stimulation. We tested the implant in vivo and were able to elicit both neural and behavioural responses. The implants continued to function for up to five months in vivo. While targeted to cochlear stimulation, with appropriate electrode arrays the stimulator is well suited to stimulating other neurons within the peripheral or central nervous systems. Moreover, it includes significant on-board data acquisition and processing capabilities, which could potentially make it a useful platform for telemetry applications, where there is a need to chronically monitor physiological variables in unrestrained animals.

  2. A fully implanted programmable stimulator based on wireless communication for epidural spinal cord stimulation in rats.

    PubMed

    Zhou, Hui; Xu, Qi; He, Jiping; Ren, Hangkong; Zhou, Houlun; Zheng, Kejia

    2012-03-15

    Clinical research indicates that the epidural spinal cord stimulation (ESCS) has shown potential in promoting locomotor recovery in patients with incomplete spinal cord injury (ISCI). This paper presents the development of a fully implantable voltage-regulated stimulator with bi-directional wireless communication for investigating underlying neural mechanisms of ESCS facilitating motor function improvement. The stimulation system consists of a computer, an external controller, an implantable pulse generator (IPG), a magnet, the extension leads and a stimulation electrode. The telemetry transmission between the IPG and the external controller is achieved by a commercially available transceiver chip with 2.4GHz carrier band. The magnet is used to activate the IPG only when necessary to minimize the power consumption. The encapsulated IPG measures 33mm×24mm×8mm, with a total mass of ∼12.6g. Feasibility experiments are conducted in three Sprague-Dawley rats to validate the function of the stimulator, and to investigate the relationship between lumbar-sacral ESCS and hindlimb electromyography (EMG) responses. The results show that the stimulation system provides an effective tool for investigation of ESCS application in motor function recovery in small animals. PMID:22085835

  3. A Fully-Implantable Cochlear Implant SoC with Piezoelectric Middle-Ear Sensor and Arbitrary Waveform Neural Stimulation

    PubMed Central

    Yip, Marcus; Jin, Rui; Nakajima, Hideko Heidi; Stankovic, Konstantina M.; Chandrakasan, Anantha P.

    2015-01-01

    A system-on-chip for an invisible, fully-implantable cochlear implant is presented. Implantable acoustic sensing is achieved by interfacing the SoC to a piezoelectric sensor that detects the sound-induced motion of the middle ear. Measurements from human cadaveric ears demonstrate that the sensor can detect sounds between 40 and 90 dB SPL over the speech bandwidth. A highly-reconfigurable digital sound processor enables system power scalability by reconfiguring the number of channels, and provides programmable features to enable a patient-specific fit. A mixed-signal arbitrary waveform neural stimulator enables energy-optimal stimulation pulses to be delivered to the auditory nerve. The energy-optimal waveform is validated with in-vivo measurements from four human subjects which show a 15% to 35% energy saving over the conventional rectangular waveform. Prototyped in a 0.18 μm high-voltage CMOS technology, the SoC in 8-channel mode consumes 572 μW of power including stimulation. The SoC integrates implantable acoustic sensing, sound processing, and neural stimulation on one chip to minimize the implant size, and proof-of-concept is demonstrated with measurements from a human cadaver ear. PMID:26251552

  4. Fully Implantable Peripheral Nerve Stimulation for the Treatment of Hemiplegic Shoulder Pain: A Case Report

    PubMed Central

    Nguyen, Vu Q. C.; Bock, William C.; Groves, Christine C.; Whitney, Marybeth; Bennett, Maria E.; Lechman, Tina E.; Strother, Robert; Grill, Julie H.; Stager, Kathryn W.; Chae, John

    2014-01-01

    This case report describes the first participant treated with a fully-implantable, single-lead peripheral nerve stimulation (PNS) system for refractory hemiplegic shoulder pain (HSP). During the 6-wk trial-stage, a temporary lead was placed percutaneously near the terminal branches of the axillary nerve to the deltoid. The primary outcome measure was the Brief Pain Inventory-Short Form Question 3 (BPI-3), a 0–10 pain numeric rating scale. The participant experienced 75% pain reduction and proceeded to the implant-stage where he received a single-lead, implantable pulse generator. After 3-wks, the participant became pain-free. However, 7-wks after implantation, the system was turned off due to an unrelated acute medical illness. HSP reemerged with BPI-3 of 9. After 11-wks of recovery, PNS was reinitiated and the participant became pain-free through the 9-months follow-up. At 12-months, BPI-3 was a 1. This case report demonstrates the feasibility of a single-lead, fully-implantable PNS system for refractory HSP. PMID:25251248

  5. A Fully Implantable Stimulator With Wireless Power and Data Transmission for Experimental Investigation of Epidural Spinal Cord Stimulation.

    PubMed

    Xu, Qi; Hu, Dingyin; Duan, Bingyu; He, Jiping

    2015-07-01

    Epidural spinal cord stimulation (ESCS) combined with partial weight-bearing therapy (PWBT) has been shown to facilitate recovery of functional walking for individuals after spinal cord injury (SCI). The investigation of neural mechanisms of recovery from SCI under this treatment has been conducted broadly in rodent models, yet a suitable ESCS system is still unavailable. This paper describes a practical, programmable, and fully implantable stimulator for laboratory research on rats to explore fundamental neurophysiological principles for functional recovery after SCI. The ESCS system is composed of a personal digital assistant (PDA), an external controller, an implantable pulse generator (IPG), lead extension, and stimulating electrodes. The stimulation parameters can be programmed and adjusted through a graphical user interface on the PDA. The external controller is placed on the rat back and communicates with the PDA via radio-frequency (RF) telemetry. An RF carrier from the class-E power amplifier in the external controller provides both data and power for the IPG through an inductive link. The IPG is built around a microcontroller unit to generate voltage-regulated pulses delivered to the bipolar electrode for ESCS in rats. The encapsulated IPG measures 22 mm × 23 mm × 7 mm with a mass of  ∼  3.78 g. This fully implantable batteryless stimulator provided a simplified and efficient method to carry out chronic experiments in untethered animals for medical electro-neurological research. PMID:25680207

  6. A fully implantable stimulator with wireless power and data transmission for experimental use in epidural spinal cord stimulation.

    PubMed

    Xu, Qi; Li, Jun; Han, Wenjuan; Zhou, Houlun

    2011-01-01

    Epidural spinal cord stimulation (ESCS) combined with partial weight bearing therapy (PWBT) has been reported to facilitate recovery of functional walking for individuals after chronic incomplete spinal cord injury. This paper describes a low cost, fully implantable, advanced ESCS stimulator that can be manufactured in a research laboratory for use in small animals. The system is composed of four main parts: an external personal digital assistant (PDA), an external controller, an implantable pulse generator (IPG), lead extension and electrode. The PDA allows the experimenter to program the stimulation parameters through a user-friendly graphical interface. The external controller placed on the rat back communicates with PDA via RF telemetry. The IPG generates the biphasic charge-balanced voltage-regulated pulses, which are delivered to the bipolar electrode by the lead extension to achieve chronic ESCS in freely moving rats. A RF carrier from the Class-E amplifier in the external controller provides both data and power for the implanted circuitry through a closely coupled inductive link. The IPG is hermetically packaged using a silicon elastomer and measures 22 mm × 23 mm × 7 mm with a mass of ~3.78 g.

  7. A fully implantable stimulator with wireless power and data transmission for experimental use in epidural spinal cord stimulation.

    PubMed

    Xu, Qi; Li, Jun; Han, Wenjuan; Zhou, Houlun

    2011-01-01

    Epidural spinal cord stimulation (ESCS) combined with partial weight bearing therapy (PWBT) has been reported to facilitate recovery of functional walking for individuals after chronic incomplete spinal cord injury. This paper describes a low cost, fully implantable, advanced ESCS stimulator that can be manufactured in a research laboratory for use in small animals. The system is composed of four main parts: an external personal digital assistant (PDA), an external controller, an implantable pulse generator (IPG), lead extension and electrode. The PDA allows the experimenter to program the stimulation parameters through a user-friendly graphical interface. The external controller placed on the rat back communicates with PDA via RF telemetry. The IPG generates the biphasic charge-balanced voltage-regulated pulses, which are delivered to the bipolar electrode by the lead extension to achieve chronic ESCS in freely moving rats. A RF carrier from the Class-E amplifier in the external controller provides both data and power for the implanted circuitry through a closely coupled inductive link. The IPG is hermetically packaged using a silicon elastomer and measures 22 mm × 23 mm × 7 mm with a mass of ~3.78 g. PMID:22256007

  8. Deep tissue targeted near-infrared optogenetic stimulation using fully implantable upconverting light bulbs.

    PubMed

    Chamanzar, Maysamreza; Garfield, David J; Iafrati, Jillian; Sohal, Vikaas; Chan, Emory; Cohen, Bruce; Schuck, P James; Maharbiz, Michel M

    2015-08-01

    We demonstrate for the first time, the possibility of targeted optogenetic stimulation of neurons deep into brain tissue (>2 mm) in a minimally-invasive way by sending near-infrared light through tissue to excite passive lanthanide-doped blue-emitting upconverting nanocrystals (UCNPs) encapsulated in Parylene C microstructure light bulbs that emit visible (blue) light and locally excite opsins with high spatial resolution. PMID:26736388

  9. Extradural implantation of sacral anterior root stimulators.

    PubMed Central

    Sauerwein, D; Ingunza, W; Fischer, J; Madersbacher, H; Polkey, C E; Brindley, G S; Colombel, P; Teddy, P

    1990-01-01

    A technique for extradural deafferentation of the S2 to S5 segments and extradural implantation of stimulating electrodes is described, and its application to twelve patients with spinal cord lesions is reported. Nine patients use their implants for micturition, and seven are fully continent. The advantages and disadvantages of this technique compared with the more usual intrathecal procedure are discussed. PMID:2213045

  10. A Fully-Implanted Intramuscular Bipolar Myoelectric Signal Recording Electrode

    PubMed Central

    Memberg, William D.; Stage, Thomas G.; Kirsch, Robert F.

    2014-01-01

    Objectives To develop a fully-implanted, intramuscular, bipolar, myoelectric signal recording electrode (IM-MES) for functional electrical stimulation (FES), prosthetic myoelectric control, and other permanently implantable systems. Materials and Methods An existing fully-implanted intramuscular stimulating electrode was modified at each end to allow bipolar recording. The design change also required a modification of the implantation method. Mechanical and in vivo testing was performed on the novel components of the electrode. The first clinical application is also described. Results The electrode design modifications did not create any areas of excess mechanical strain on the wires at the distal end where the leads were wound into electrode surfaces. In vivo testing showed that the IM-MES electrode recorded myoelectric signals that were equivalent to an existing epimysial MES electrode. The modified implantation method was simple to implement. The IM-MES electrode was used in an upper extremity FES system in an individual with a spinal cord injury, and provided signals that were suitable for a command signal. Conclusions A fully-implanted, bipolar intramuscular recording electrode (IM-MES) was developed. Implantation of the IM-MES is straightforward and almost any muscle can be targeted. Testing has been performed to demonstrate the suitability of the IM-MES electrode for clinical use. Initial clinical applications were successful. PMID:24612356

  11. Polymeric Packaging for Fully Implantable Wireless Neural Microsensors

    PubMed Central

    Aceros, Juan; Yin, Ming; Borton, David A.; Patterson, William R.; Bull, Christopher; Nurmikko, Arto V.

    2014-01-01

    We present polymeric packaging methods used for subcutaneous, fully implantable, broadband, and wireless neurosensors. A new tool for accelerated testing and characterization of biocompatible polymeric packaging materials and processes is described along with specialized test units to simulate our fully implantable neurosensor components, materials and fabrication processes. A brief description of the implantable systems is presented along with their current encapsulation methods based on polydimethylsiloxane (PDMS). Results from in-vivo testing of multiple implanted neurosensors in swine and non-human primates are presented. Finally, a novel augmenting polymer thin film material to complement the currently employed PDMS is introduced. This thin layer coating material is based on the Plasma Enhanced Chemical Vapor Deposition (PECVD) process of Hexamethyldisiloxane (HMDSO) and Oxygen (O2). PMID:23365999

  12. Considering optogenetic stimulation for cochlear implants.

    PubMed

    Jeschke, Marcus; Moser, Tobias

    2015-04-01

    Electrical cochlear implants are by far the most successful neuroprostheses and have been implanted in over 300,000 people worldwide. Cochlear implants enable open speech comprehension in most patients but are limited in providing music appreciation and speech understanding in noisy environments. This is generally considered to be due to low frequency resolution as a consequence of wide current spread from stimulation contacts. Accordingly, the number of independently usable stimulation channels is limited to less than a dozen. As light can be conveniently focused, optical stimulation might provide an alternative approach to cochlear implants with increased number of independent stimulation channels. Here, we focus on summarizing recent work on optogenetic stimulation as one way to develop optical cochlear implants. We conclude that proof of principle has been presented for optogenetic stimulation of the cochlea and central auditory neurons in rodents as well as for the technical realization of flexible μLED-based multichannel cochlear implants. Still, much remains to be done in order to advance the technique for auditory research and even more for eventual clinical translation. This article is part of a Special Issue entitled . PMID:25601298

  13. Implantable neurotechnologies: electrical stimulation and applications.

    PubMed

    Nag, Sudip; Thakor, Nitish V

    2016-01-01

    Neural stimulation using injected electrical charge is widely used both in functional therapies and as an experimental tool for neuroscience applications. Electrical pulses can induce excitation of targeted neural pathways that aid in the treatment of neural disorders or dysfunction of the central and peripheral nervous system. In this review, we summarize the recent trends in the field of electrical stimulation for therapeutic interventions of nervous system disorders, such as for the restoration of brain, eye, ear, spinal cord, nerve and muscle function. Neural prosthetic applications are discussed, and functional electrical stimulation parameters for treating such disorders are reviewed. Important considerations for implantable packaging and enhancing device reliability are also discussed. Neural stimulators are expected to play a profound role in implantable neural devices that treat disorders and help restore functions in injured or disabled nervous system. PMID:26753775

  14. Ultraminiature encapsulated accelerometers as a fully implantable sensor for implantable hearing aids.

    PubMed

    Park, Woo-Tae; O'Connor, Kevin N; Chen, Kuan-Lin; Mallon, Joseph R; Maetani, Toshiki; Dalal, Parmita; Candler, Rob N; Ayanoor-Vitikkate, Vipin; Roberson, Joseph B; Puria, Sunil; Kenny, Thomas W

    2007-12-01

    Experiments were conducted to evaluate a silicon accelerometer as an implantable sound sensor for implantable hearing aids. The main motivation of this study is to find an alternative sound sensor that is implantable inside the body, yet does not suffer from the signal attenuation from the body. The merit of the accelerometer sensor as a sound sensor will be that it will utilize the natural mechanical conduction in the middle ear as a source of the vibration. With this kind of implantable sound sensor, a totally implantable hearing aid is feasible. A piezoresistive silicon accelerometer that is completely encapsulated with a thin silicon film and long flexible flex-circuit electrical cables were used for this study. The sensor is attached on the middle ear ossicles and measures the vibration transmitted from the tympanic membrane due to the sound in the ear canal. In this study, the sensor is fully characterized on a human cadaveric temporal bone preparation.

  15. An implantable neural stimulator for intraspinal microstimulation.

    PubMed

    Troyk, Philip R; Mushahwar, Vivian K; Stein, Richard B; Suh, Sungjae; Everaert, Dirk; Holinski, Brad; Hu, Zhe; DeMichele, Glenn; Kerns, Douglas; Kayvani, Kevin

    2012-01-01

    This paper reports on a wireless stimulator device for use in animal experiments as part of an ongoing investigation into intraspinal stimulation (ISMS) for restoration of walking in humans with spinal cord injury. The principle behind using ISMS is the activation of residual motor-control neural networks within the spinal cord ventral horn below the level of lesion following a spinal cord injury. The attractiveness to this technique is that a small number of electrodes can be used to induce bilateral walking patterns in the lower limbs. In combination with advanced feedback algorithms, ISMS has the potential to restore walking for distances that exceed that produced by other types of functional electrical stimulation. Recent acute animal experiments have demonstrated the feasibility of using ISMS to produce the coordinated walking patterns. Here we described a wireless implantable stimulation system to be used in chronic animal experiments and for providing the basis for a system suitable for use in humans. Electrical operation of the wireless system is described, including a demonstration of reverse telemetry for monitoring the stimulating electrode voltages. PMID:23366038

  16. 21 CFR 882.5860 - Implanted neuromuscular stimulator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... electrical stimulation to a patient's peroneal or femoral nerve to cause muscles in the leg to contract, thus improving the gait in a patient with a paralyzed leg. The stimulator consists of an implanted receiver...

  17. 21 CFR 882.5860 - Implanted neuromuscular stimulator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... electrical stimulation to a patient's peroneal or femoral nerve to cause muscles in the leg to contract, thus improving the gait in a patient with a paralyzed leg. The stimulator consists of an implanted receiver...

  18. Soft, stretchable, fully implantable miniaturized optoelectronic systems for wireless optogenetics

    PubMed Central

    Park, Sung Il; Brenner, Daniel S.; Shin, Gunchul; Morgan, Clinton D.; Copits, Bryan A.; Chung, Ha Uk; Pullen, Melanie Y.; Noh, Kyung Nim; Davidson, Steve; Oh, Soong Ju; Yoon, Jangyeol; Jang, Kyung-In; Samineni, Vijay K.; Norman, Megan; Grajales-Reyes, Jose G.; Vogt, Sherri K; Sundaram, Saranya S.; Wilson, Kellie M.; Ha, Jeong Sook; Xu, Renxiao; Pan, Taisong; Kim, Tae-il; Huang, Yonggang; Montana, Michael C.; Golden, Judith P.; Bruchas, Michael R.; Gereau, Robert W.; Rogers, John A.

    2016-01-01

    Optogenetics allows rapid, temporally specific control of neuronal activity via targeted expression and activation of light-sensitive proteins. Implementation typically requires remote light sources and fiber-optic delivery schemes that impose significant physical constraints on natural behaviors. In this report we bypass these limitations using novel technologies that combine thin, mechanically soft neural interfaces with fully implantable, stretchable wireless radio power and control systems. The resulting devices achieve optogenetic modulation of the spinal cord and peripheral nervous system. This is demonstrated with two form factors; stretchable film appliques that interface directly with peripheral nerves, and flexible filaments that insert into the narrow confines of the spinal epidural space. These soft, thin devices are minimally invasive, and histological tests suggest they can be used in chronic studies. We demonstrate the power of this technology by modulating peripheral and spinal pain circuitry, providing evidence for the potential widespread use of these devices in research and future clinical applications of optogenetics outside the brain. PMID:26551059

  19. Design and operation of a fully implantable SMA actuated implant for correcting short bowel syndrome

    NASA Astrophysics Data System (ADS)

    Utter, Brent; Luntz, Jonathan; Brei, Diann; Teitelbaum, Daniel; Okawada, Manabu; Miyasaka, Eiichi

    2009-03-01

    Short Bowel Syndrome (SBS) is medical condition characterized by insufficient small intestine length, leading to improper nutrient absorption and significant mortality rates. The complications of current treatment methods have encouraged the development of a novel treatment method based on mechanotransduction, the process through which mechanical tensile loading induces longitudinal growth of intestine. Animal based studies with simple extension devices have demonstrated the potential of the treatment to grow healthy bowel, but an implantable device suitable for clinical use remains undeveloped. This paper presents the development of an instrumented fully implantable bowel extender based upon a shape memory alloy driven linear ratchet that can be controlled and monitored remotely. The overall bowel extender system is described with respect to specifications for pig experimental tests. The functionality of the mechanical and electrical subsystems of the device are detailed and experimentally validated on the bench top, in segments of living bowel tissue removed from a pig, and in cadaveric pigs. Mechanical loading characteristics and safe load limits on bowel tissue are identified. Results from these experiments establish the readiness of the device to be tested in living pigs, enabling studies to move one step closer to clinical studies.

  20. 21 CFR 882.5860 - Implanted neuromuscular stimulator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Date PMA or notice of completion of PDP is required. A PMA or notice of completion of a PDP for a.... Any other implanted neuromuscular stimulator shall have an approved PMA or declared completed PDP...

  1. Remote Electrical Stimulation by Means of Implanted Rectifiers

    PubMed Central

    Ivorra, Antoni

    2011-01-01

    Miniaturization of active implantable medical devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants – batteries and inductive couplers – comprise bulky parts which, in most cases, are significantly larger than the circuitry they feed. Here, for overcoming such miniaturization bottleneck in the case of implants for electrical stimulation, it is proposed to make those implants act as rectifiers of high frequency bursts supplied by remote electrodes. In this way, low frequency currents will be generated locally around the implant and these low frequency currents will perform stimulation of excitable tissues whereas the high frequency currents will cause only innocuous heating. The present study numerically demonstrates that low frequency currents capable of stimulation can be produced by a miniature device behaving as a diode when high frequency currents, neither capable of thermal damage nor of stimulation, flow through the tissue where the device is implanted. Moreover, experimental evidence is provided by an in vivo proof of concept model consisting of an anesthetized earthworm in which a commercial diode was implanted. With currently available microelectronic techniques, very thin stimulation capsules (diameter <500 µm) deliverable by injection are easily conceivable. PMID:21850274

  2. Remote electrical stimulation by means of implanted rectifiers.

    PubMed

    Ivorra, Antoni

    2011-01-01

    Miniaturization of active implantable medical devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants--batteries and inductive couplers--comprise bulky parts which, in most cases, are significantly larger than the circuitry they feed. Here, for overcoming such miniaturization bottleneck in the case of implants for electrical stimulation, it is proposed to make those implants act as rectifiers of high frequency bursts supplied by remote electrodes. In this way, low frequency currents will be generated locally around the implant and these low frequency currents will perform stimulation of excitable tissues whereas the high frequency currents will cause only innocuous heating. The present study numerically demonstrates that low frequency currents capable of stimulation can be produced by a miniature device behaving as a diode when high frequency currents, neither capable of thermal damage nor of stimulation, flow through the tissue where the device is implanted. Moreover, experimental evidence is provided by an in vivo proof of concept model consisting of an anesthetized earthworm in which a commercial diode was implanted. With currently available microelectronic techniques, very thin stimulation capsules (diameter <500 µm) deliverable by injection are easily conceivable. PMID:21850274

  3. Composite implants coated with biodegradable polymers prevent stimulating tumor progression

    NASA Astrophysics Data System (ADS)

    Litviakov, N. V.; Tverdokhlebov, S. I.; Perelmuter, V. M.; Kulbakin, D. E.; Bolbasov, E. N.; Tsyganov, M. M.; Zheravin, A. A.; Svetlichnyi, V. A.; Cherdyntseva, N. V.

    2016-08-01

    In this experiment we studied oncologic safety of model implants created using the solution blow spinning method with the use of the PURASORB PL-38 polylactic acid polymer and organic mineral filler which was obtained via laser ablation of a solid target made of dibasic calcium phosphate dihydrate. For this purpose the implant was introduced into the area of Wistar rats' iliums, and on day 17 after the surgery the Walker sarcoma was transplanted into the area of the implant. We evaluated the implant's influence on the primary tumor growth, hematogenous and lymphogenous metastasis of the Walker sarcoma. In comparison with sham operated animals the implant group demonstrated significant inhibition of hematogenous metastasis on day 34 after the surgery. The metastasis inhibition index (MII) equaled 94% and the metastases growth inhibition index (MGII) equaled 83%. The metastasis frequency of the Walker sarcoma in para aortic lymph nodes in the implant group was not statistically different from the control frequency; there was also no influence of the implant on the primary tumor growth noted. In case of the Walker sarcoma transplantation into the calf and the palmar pad of the ipsilateral limb to the one with the implant in the ilium, we could not note any attraction of tumor cells to the implant area, i.e. stimulation of the Walker sarcoma relapse by the implant. Thus, the research concluded that the studied implant meets the requirements of oncologic safety.

  4. Chronic cortical and electromyographic recordings from a fully implantable device: preclinical experience in a nonhuman primate

    NASA Astrophysics Data System (ADS)

    Ryapolova-Webb, Elena; Afshar, Pedram; Stanslaski, Scott; Denison, Tim; de Hemptinne, Coralie; Bankiewicz, Krystof; Starr, Philip A.

    2014-02-01

    Objective. Analysis of intra- and perioperatively recorded cortical and basal ganglia local field potentials in human movement disorders has provided great insight into the pathophysiology of diseases such as Parkinson's, dystonia, and essential tremor. However, in order to better understand the network abnormalities and effects of chronic therapeutic stimulation in these disorders, long-term recording from a fully implantable data collection system is needed. Approach. A fully implantable investigational data collection system, the Activa® PC + S neurostimulator (Medtronic, Inc., Minneapolis, MN), has been developed for human use. Here, we tested its utility for extended intracranial recording in the motor system of a nonhuman primate. The system was attached to two quadripolar paddle arrays: one covering sensorimotor cortex, and one covering a proximal forelimb muscle, to study simultaneous cortical field potentials and electromyography during spontaneous transitions from rest to movement. Main results. Over 24 months of recording, movement-related changes in physiologically relevant frequency bands were readily detected, including beta and gamma signals at approximately 2.5 μV/\\sqrtHz and 0.7 μV/\\sqrt{Hz}, respectively. The system architecture allowed for flexible recording configurations and algorithm triggered data recording. In the course of physiological analyses, sensing artifacts were observed (˜1 μVrms stationary tones at fixed frequency), which were mitigated either with post-processing or algorithm design and did not impact the scientific conclusions. Histological examination revealed no underlying tissue damage; however, a fibrous capsule had developed around the paddles, demonstrating a potential mechanism for the observed signal amplitude reduction. Significance. This study establishes the usefulness of this system in measuring chronic brain and muscle signals. Use of this system may potentially be valuable in human trials of chronic brain

  5. A fully integrated microbattery for an implantable microelectromechanical system

    NASA Astrophysics Data System (ADS)

    Albano, F.; Lin, Y. S.; Blaauw, D.; Sylvester, D. M.; Wise, K. D.; Sastry, A. M.

    The Wireless Integrated Microsystems Engineering Research Center's Intraocular Sensor (WIMS-ERC IOS) was studied as a model system for an integrated, autonomous implantable device. In the present study, we had four objectives: (1) select and designing an optimized power supply for the WIMS-IOS; (2) develop a fabrication technique allowing small scale, low-cost, and integrable fabrication for CMOS systems, and experimentally demonstrate a microscopic power source; (3) map capacity and lifetime of several fabricated microbatteries; (4) determine the effects of miniaturization on capacity, lifetime and device architecture. Physical vapor deposition (PVD) was used to deposit thin layers (≤1 μm) of metal sequentially onto glass substrates (SiO 2, as used in the device). To map the influence of size over cell capacity and cycle life, we fabricated and tested five stand-alone cells using a Solartron ® 1470E battery tester and a Maccor ® 4000 series tester. A sixth battery was fabricated to investigate the effects of system integration, variable discharge rate and size reduction simultaneously. The highest experimental capacity among the larger cells O(cm 2) was 100 μAh, achieved by IOS-C-1 at 250 μA (1.4 C) discharge. Among O(mm 2) cells, IOS-M-1 achieved the highest capacity (2.75 μAh, ∼76% of theoretical) at 2.5 μA discharge (0.7 C rate).

  6. Implantable optical-electrode device for stimulation of spinal motoneurons

    NASA Astrophysics Data System (ADS)

    Matveev, M. V.; Erofeev, A. I.; Zakharova, O. A.; Pyatyshev, E. N.; Kazakin, A. N.; Vlasova, O. L.

    2016-08-01

    Recent years, optogenetic method of scientific research has proved its effectiveness in the nerve cell stimulation tasks. In our article we demonstrate an implanted device for the spinal optogenetic motoneurons activation. This work is carried out in the Laboratory of Molecular Neurodegeneration of the Peter the Great St. Petersburg Polytechnic University, together with Nano and Microsystem Technology Laboratory. The work of the developed device is based on the principle of combining fiber optic light stimulation of genetically modified cells with the microelectrode multichannel recording of neurons biopotentials. The paper presents a part of the electrode implant manufacturing technique, combined with the optical waveguide of ThorLabs (USA).

  7. An Implanted, Stimulated Muscle Powered Piezoelectric Generator

    NASA Technical Reports Server (NTRS)

    Lewandowski, Beth; Gustafson, Kenneth; Kilgore, Kevin

    2007-01-01

    A totally implantable piezoelectric generator system able to harness power from electrically activated muscle could be used to augment the power systems of implanted medical devices, such as neural prostheses, by reducing the number of battery replacement surgeries or by allowing periods of untethered functionality. The features of our generator design are no moving parts and the use of a portion of the generated power for system operation and regulation. A software model of the system has been developed and simulations have been performed to predict the output power as the system parameters were varied within their constraints. Mechanical forces that mimic muscle forces have been experimentally applied to a piezoelectric generator to verify the accuracy of the simulations and to explore losses due to mechanical coupling. Depending on the selection of system parameters, software simulations predict that this generator concept can generate up to approximately 700 W of power, which is greater than the power necessary to drive the generator, conservatively estimated to be 50 W. These results suggest that this concept has the potential to be an implantable, self-replenishing power source and further investigation is underway.

  8. Cochlear Implant Spatial Selectivity with Monopolar, Bipolar and Tripolar Stimulation

    PubMed Central

    Zhu, Ziyan; Tang, Qing; Zeng, Fan-Gang; Guan, Tian; Ye, Datian

    2011-01-01

    Sharp spatial selectivity is critical to auditory performance, particularly in pitch related tasks. Most contemporary cochlear implants have employed monopolar stimulation that produces broad electric fields, which presumably contribute to poor pitch and pitch-related performance by implant users. Bipolar or tripolar stimulation can generate focused electric fields but requires higher current to reach threshold and, more interestingly, has not produced any apparent improvement in cochlear implant performance. The present study addressed this dilemma by measuring psychophysical and physiological spatial selectivity with both broad and focused stimulations in the same cohort of subjects. Different current levels were adjusted by systematically measuring loudness growth for each stimulus, each stimulation mode, and in each subject. Both psychophysical and physiological measures showed that, although focused stimulation produced significantly sharper spatial tuning than monopolar stimulation, it could shift the tuning position or even split the tuning tips. The altered tuning with focused stimulation is interpreted as a result of poor electrode-to-neuron interface in the cochlea, and is suggested to be mainly responsible for the lack of consistent improvement in implant performance. A linear model could satisfactorily quantify the psychophysical and physiological data and derive the tuning width. Significant correlation was found between the individual physiological and psychophysical tuning widths, and the correlation was improved by log-linearly transforming the physiological data to predict the psychophysical data. Because the physiological measure took only one-tenth of the time of the psychophysical measure, the present model is of high clinical significance in terms of predicting and improving cochlear implant performance. PMID:22138630

  9. 21 CFR 882.5880 - Implanted spinal cord stimulator for pain relief.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Implanted spinal cord stimulator for pain relief... Implanted spinal cord stimulator for pain relief. (a) Identification. An implanted spinal cord stimulator for pain relief is a device that is used to stimulate electrically a patient's spinal cord to...

  10. 21 CFR 882.5880 - Implanted spinal cord stimulator for pain relief.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Implanted spinal cord stimulator for pain relief... Implanted spinal cord stimulator for pain relief. (a) Identification. An implanted spinal cord stimulator for pain relief is a device that is used to stimulate electrically a patient's spinal cord to...

  11. 21 CFR 882.5870 - Implanted peripheral nerve stimulator for pain relief.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Implanted peripheral nerve stimulator for pain....5870 Implanted peripheral nerve stimulator for pain relief. (a) Identification. An implanted peripheral nerve stimulator for pain relief is a device that is used to stimulate electrically a peripheral...

  12. 21 CFR 882.5880 - Implanted spinal cord stimulator for pain relief.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Implanted spinal cord stimulator for pain relief... Implanted spinal cord stimulator for pain relief. (a) Identification. An implanted spinal cord stimulator for pain relief is a device that is used to stimulate electrically a patient's spinal cord to...

  13. 21 CFR 882.5880 - Implanted spinal cord stimulator for pain relief.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Implanted spinal cord stimulator for pain relief... Implanted spinal cord stimulator for pain relief. (a) Identification. An implanted spinal cord stimulator for pain relief is a device that is used to stimulate electrically a patient's spinal cord to...

  14. 21 CFR 882.5870 - Implanted peripheral nerve stimulator for pain relief.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Implanted peripheral nerve stimulator for pain....5870 Implanted peripheral nerve stimulator for pain relief. (a) Identification. An implanted peripheral nerve stimulator for pain relief is a device that is used to stimulate electrically a peripheral...

  15. 21 CFR 882.5870 - Implanted peripheral nerve stimulator for pain relief.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Implanted peripheral nerve stimulator for pain....5870 Implanted peripheral nerve stimulator for pain relief. (a) Identification. An implanted peripheral nerve stimulator for pain relief is a device that is used to stimulate electrically a peripheral...

  16. 21 CFR 882.5870 - Implanted peripheral nerve stimulator for pain relief.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Implanted peripheral nerve stimulator for pain....5870 Implanted peripheral nerve stimulator for pain relief. (a) Identification. An implanted peripheral nerve stimulator for pain relief is a device that is used to stimulate electrically a peripheral...

  17. 21 CFR 882.5870 - Implanted peripheral nerve stimulator for pain relief.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Implanted peripheral nerve stimulator for pain....5870 Implanted peripheral nerve stimulator for pain relief. (a) Identification. An implanted peripheral nerve stimulator for pain relief is a device that is used to stimulate electrically a peripheral...

  18. 21 CFR 882.5880 - Implanted spinal cord stimulator for pain relief.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Implanted spinal cord stimulator for pain relief... Implanted spinal cord stimulator for pain relief. (a) Identification. An implanted spinal cord stimulator for pain relief is a device that is used to stimulate electrically a patient's spinal cord to...

  19. Waveform efficiency analysis of auditory nerve fiber stimulation for cochlear implants.

    PubMed

    Lotfi Navaii, Mehdi; Sadjedi, Hamed; Jalali, Mohsen

    2013-09-01

    Evaluation of the electrical stimulation efficiency of various stimulating waveforms is an important issue for efficient neural stimulator design. Concerning the implantable micro devices design, it is also necessary to consider the feasibility of hardware implementation of the desired waveforms. In this paper, the charge, power and energy efficiency of four waveforms (i.e. square, rising ramp, triangular and rising ramp-decaying exponential) in various durations have been simulated and evaluated based on the computational model of the auditory nerve fibers. Moreover, for a fair comparison of their feasibility, a fully integrated current generator circuit has been developed so that the desired stimulating waveforms can be generated. The simulation results show that stimulation with the square waveforms is a proper choice in short and intermediate durations while the rising ramp-decaying exponential or triangular waveforms can be employed for long durations. PMID:23918258

  20. An implant for chronic selective stimulation of nerves.

    PubMed

    Bugbee, M; Donaldson, N N; Lickel, A; Rijkhoff, N J; Taylor, J

    2001-01-01

    An implantable stimulator system has been developed for nerve stimulation. The system is capable of stimulating selectively, either by fibre position, fibre size or by sending action potentials in one direction only, based on the use of nerve cuffs. The stimulator produces either quasi-trapezoidal current pulses, to allow anodal blocking, or conventional rectangular-shaped current pulses, of amplitude 20 microA to 5 mA (in 20 microA steps) with duration of 16 micros to 1 ms (in 8 micros steps). For safety, both active and passive charge balancing is used. The amplitude of the active charge-balancing phase can be varied between 1/7 and 1/47 of the pulse amplitude. During manufacture, each implant is customised so as to drive either 6 quasi-tripolar (dipolar), 4 tripolar or 2 pentapolar cuffs. Possible applications of the device are: improved defaecation and bladder voiding after spinal cord injury, by stimulation of the sacral motor roots; neuromodulation to reduce hyperreflexia without concomitant muscle contractions; in stroke patients, to enable balanced inversion-eversion while dorsiflexing the ankle by stimulating the peroneal nerve. It may also be used in chronic animal experiments.This paper describes the implant system, its hardware and communication protocol, and shows results from in vitro tests of the device and the first acute anodal-blocking experiments in pigs. PMID:11344005

  1. [Implantable nerve stimulation for obstructive sleep apnea hypopnea syndrome].

    PubMed

    Afonso Delgado, Lidia; Micoulaud Franchi, Jean-Arthur; Monteyrol, Pierre-Jean; Philip, Pierre

    2016-02-01

    Obstructive sleep apnea hypopnea syndrome (OSAHS) is a common disorder that has been identified as a contributor to cardiovascular disease making it a major public health problem. Continuous positive airway pressure is the standard treatment but compliance is suboptimal. Mandibular advancement devices and surgery have limited indications, inconstant efficiency and potential irreversible side effects. Stimulation of the hypoglossal nerve, that innervates the genioglossus, a protrusor muscle of the tongue, is now a new treatment option for moderate and severe cases of OSAHS. Two types of stimulation are currently available: stimulation synchronous with inspiration and continuous stimulation. The indication of each type of stimulation and long-term effects still need to be assessed but the implantable nerve stimulation is a promising treatment for patients without a therapy solution so far.

  2. Pudendal Nerve Stimulation and Block by a Wireless Controlled Implantable Stimulator in Cats

    PubMed Central

    Yang, Guangning; Wang, Jicheng; Shen, Bing; Roppolo, James R.; de Groat, William C.; Tai, Changfeng

    2014-01-01

    Objective To determine the functionality of a wireless controlled implantable stimulator designed for stimulation and block of the pudendal nerve. Materials and Methods In 5 cats under α-chloralose anesthesia, the stimulator was implanted underneath the skin on the left side in the lower back along the sacral spine. Two tripolar cuff electrodes were implanted bilaterally on the pudendal nerves in addition to one bipolar cuff electrode that was implanted on the left side central to the tripolar cuff electrode. The stimulator provided high frequency (5-20 kHz) biphasic stimulation waveforms to the two tripolar electrodes and low frequency (1-100 Hz) rectangular pulses to the bipolar electrode. Bladder and urethral pressures were measured to determine the effects of pudendal nerve stimulation (PNS) or block. Results The maximal (70-100 cmH2O) urethral pressure generated by 20 Hz PNS applied via the bipolar electrode was completely eliminated by the pudendal nerve block induced by the high frequency stimulation (6-15 kHz, 6-10 V) applied via the two tripolar electrodes. In a partially filled bladder 20-30 Hz PNS (2-8 V, 0.2 ms) but not 5 Hz stimulation applied via the bipolar electrode elicited a large sustained bladder contraction (45.9±13.4 to 52.0±22 cmH2O). During cystometry, the 5 Hz PNS significantly (P<0.05) increased bladder capacity to 176.5±27.1% of control capacity. Conclusions The wireless controlled implantable stimulator successfully generated the required waveforms for stimulation and block of pudendal nerve, which will be useful for restoring bladder functions after spinal cord injury (SCI). PMID:24320615

  3. SaBer DBS: a fully programmable, rechargeable, bilateral, charge-balanced preclinical microstimulator for long-term neural stimulation

    PubMed Central

    Ewing, Samuel G.; Porr, Bernd; Riddell, John; Winter, Christine; Grace, Anthony A.

    2013-01-01

    To effectively study the mechanisms by which deep brain stimulation (DBS) produces its therapeutic benefit and to evaluate new therapeutic indications, it is vital to administer DBS over an extended period of time in awake, freely behaving animals. To date multiple preclinical stimulators have been designed and described. However, these stimulators have failed to incorporate some of the design criteria necessary to provide a system analogous to those used clinically. Here we define these design criteria and propose an improved and complete preclinical DBS system. This system is fully programmable in frequency, pulse-width and current amplitude, has a rechargeable battery and delivers biphasic, charge-balanced output to two independent electrodes. The system has been optimized for either implantation or for use externally via attachment to rodent jackets. PMID:23305773

  4. A Wireless Implantable Switched-Capacitor Based Optogenetic Stimulating System

    PubMed Central

    Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen

    2015-01-01

    This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments. PMID:25570099

  5. A wireless implantable switched-capacitor based optogenetic stimulating system.

    PubMed

    Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen; Ghovanloo, Maysam

    2014-01-01

    This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments. PMID:25570099

  6. Electrophysiological channel interactions using focused multipolar stimulation for cochlear implants

    NASA Astrophysics Data System (ADS)

    George, Shefin S.; Shivdasani, Mohit N.; Wise, Andrew K.; Shepherd, Robert K.; Fallon, James B.

    2015-12-01

    Objective. Speech intelligibility with existing multichannel cochlear implants (CIs) is thought to be limited by poor spatial selectivity and interactions between CI channels caused by overlapping activation with monopolar (MP) stimulation. Our previous studies have shown that focused multipolar (FMP) and tripolar (TP) stimulation produce more restricted neural activation in the inferior colliculus (IC), compared to MP stimulation. Approach. This study explored interactions in the IC produced by simultaneous stimulation of two CI channels. We recorded multi-unit neural activity in the IC of anaesthetized cats with normal and severely degenerated spiral ganglion neuron populations in response to FMP, TP and MP stimulation from a 14 channel CI. Stimuli were applied to a ‘fixed’ CI channel, chosen toward the middle of the cochlear electrode array, and the effects of simultaneously stimulating a more apical ‘test’ CI channel were measured as a function of spatial separation between the two stimulation channels and stimulus level of the fixed channel. Channel interactions were quantified by changes in neural responses and IC threshold (i.e., threshold shift) elicited by simultaneous stimulation of two CI channels, compared to stimulation of the test channel alone. Main results. Channel interactions were significantly lower for FMP and TP than for MP stimulation (p < 0.001), whereas no significant difference was observed between FMP and TP stimulation. With MP stimulation, threshold shifts increased with decreased inter-electrode spacing and increased stimulus levels of the fixed channel. For FMP and TP stimulation, channel interactions were found to be similar for different inter-electrode spacing and stimulus levels of the fixed channel. Significance. The present study demonstrates how the degree of channel interactions in a CI can be controlled using stimulation configurations such as FMP and TP; such knowledge is essential in enhancing CI function in complex

  7. [A fully-implantable active hearing device in congenital auricular atresia].

    PubMed

    Siegert, R; Neumann, C

    2014-07-01

    Active implantable hearing devices were primarily developed for sensorineural hearing loss. The vibrator coupling mechanisms were oriented towards normal middle ear anatomy and function. The aim of this project was to modify the only fully implantable hearing device with an implantable microphone for application in congenital auricular atresia, Carina™, and to introduce the modified device into the clinic. A special prosthesis was developed for the transducer and its individual coupling achieved by a special cramping system. The system was implanted in 5 patients with congenital auricular atresia. Audiological results were good; with patients' hearing gain exceeding 30 dB HL. Anatomic limits to the system's indications and technical drawbacks are also discussed. PMID:25056646

  8. An implantable 64-channel neural interface with reconfigurable recording and stimulation.

    PubMed

    Wheeler, Jesse J; Baldwin, Keith; Kindle, Alex; Guyon, Daniel; Nugent, Brian; Segura, Carlos; Rodriguez, John; Czarnecki, Andrew; Dispirito, Hailey J; Lachapelle, John; Parks, Philip D; Moran, James; Widge, Alik S; Dougherty, Darin D; Eskandar, Emad N

    2015-08-01

    Next generation implantable medical devices will have the potential to provide more precise and effective therapies through adaptive closed-loop controllers that combine sensing and stimulation across larger numbers of electrode channels. A major challenge in the design of such devices is balancing increased functionality and channel counts with the miniaturization required for implantation within small anatomical spaces. Customized therapies will require adaptive systems capable of tuning which channels are sensed and stimulated to overcome variability in patient-specific needs, surgical placement of electrodes, and chronic physiological responses. In order to address these challenges, we have designed a miniaturized implantable fully-reconfigurable front-end system that is integrated into the distal end of an 8-wire lead, enabling up to 64 electrodes to be dynamically configured for sensing and stimulation. Full reconfigurability is enabled by two custom 32×2 cross-point switch (CPS) matrix ASICs which can route any electrode to either an amplifier with reprogrammable bandwidth and integrated ADC or to one of two independent stimulation channels that can be driven through the lead. The 8-wire circuit includes a digital interface for robust communication as well as a charge-balanced powering scheme for enhanced safety. The system is encased in a hermetic package designed to fit within a 14 mm bur-hole in the skull for neuromodulation of the brain, but could easily be adapted to enhance therapies across a broad spectrum of applications. PMID:26738108

  9. Abnormal pitch perception produced by cochlear implant stimulation.

    PubMed

    Zeng, Fan-Gang; Tang, Qing; Lu, Thomas

    2014-01-01

    Contemporary cochlear implants with multiple electrode stimulation can produce good speech perception but poor music perception. Hindered by the lack of a gold standard to quantify electric pitch, relatively little is known about the nature and extent of the electric pitch abnormalities and their impact on cochlear implant performance. Here we overcame this obstacle by comparing acoustic and electric pitch perception in 3 unilateral cochlear-implant subjects who had functionally usable acoustic hearing throughout the audiometric frequency range in the non-implant ear. First, to establish a baseline, we measured and found slightly impaired pure tone frequency discrimination and nearly perfect melody recognition in all 3 subjects' acoustic ear. Second, using pure tones in the acoustic ear to match electric pitch induced by an intra-cochlear electrode, we found that the frequency-electrode function was not only 1-2 octaves lower, but also 2 times more compressed in frequency range than the normal cochlear frequency-place function. Third, we derived frequency difference limens in electric pitch and found that the equivalent electric frequency discrimination was 24 times worse than normal-hearing controls. These 3 abnormalities are likely a result of a combination of broad electric field, distant intra-cochlear electrode placement, and non-uniform spiral ganglion cell distribution and survival, all of which are inherent to the electrode-nerve interface in contemporary cochlear implants. Previous studies emphasized on the "mean" shape of the frequency-electrode function, but the present study indicates that the large "variance" of this function, reflecting poor electric pitch discriminability, is the main factor limiting contemporary cochlear implant performance. PMID:24551131

  10. Abnormal pitch perception produced by cochlear implant stimulation.

    PubMed

    Zeng, Fan-Gang; Tang, Qing; Lu, Thomas

    2014-01-01

    Contemporary cochlear implants with multiple electrode stimulation can produce good speech perception but poor music perception. Hindered by the lack of a gold standard to quantify electric pitch, relatively little is known about the nature and extent of the electric pitch abnormalities and their impact on cochlear implant performance. Here we overcame this obstacle by comparing acoustic and electric pitch perception in 3 unilateral cochlear-implant subjects who had functionally usable acoustic hearing throughout the audiometric frequency range in the non-implant ear. First, to establish a baseline, we measured and found slightly impaired pure tone frequency discrimination and nearly perfect melody recognition in all 3 subjects' acoustic ear. Second, using pure tones in the acoustic ear to match electric pitch induced by an intra-cochlear electrode, we found that the frequency-electrode function was not only 1-2 octaves lower, but also 2 times more compressed in frequency range than the normal cochlear frequency-place function. Third, we derived frequency difference limens in electric pitch and found that the equivalent electric frequency discrimination was 24 times worse than normal-hearing controls. These 3 abnormalities are likely a result of a combination of broad electric field, distant intra-cochlear electrode placement, and non-uniform spiral ganglion cell distribution and survival, all of which are inherent to the electrode-nerve interface in contemporary cochlear implants. Previous studies emphasized on the "mean" shape of the frequency-electrode function, but the present study indicates that the large "variance" of this function, reflecting poor electric pitch discriminability, is the main factor limiting contemporary cochlear implant performance.

  11. A New Trans-Tympanic Microphone Approach for Fully Implantable Hearing Devices

    PubMed Central

    Woo, Seong Tak; Shin, Dong Ho; Lim, Hyung-Gyu; Seong, Ki-Woong; Gottlieb, Peter; Puria, Sunil; Lee, Kyu-Yup; Cho, Jin-Ho

    2015-01-01

    Fully implantable hearing devices (FIHDs) have been developed as a new technology to overcome the disadvantages of conventional acoustic hearing aids. The implantable microphones currently used in FIHDs, however, have difficulty achieving high sensitivity to environmental sounds, low sensitivity to body noise, and ease of implantation. In general, implantable microphones may be placed under the skin in the temporal bone region of the skull. In this situation, body noise picked up during mastication and touching can be significant, and the layer of skin and hair can both attenuate and distort sounds. The new approach presently proposed is a microphone implanted at the tympanic membrane. This method increases the microphone’s sensitivity by utilizing the pinna’s directionally dependent sound collection capabilities and the natural resonances of the ear canal. The sensitivity and insertion loss of this microphone were measured in human cadaveric specimens in the 0.1 to 16 kHz frequency range. In addition, the maximum stable gain due to feedback between the trans-tympanic microphone and a round-window-drive transducer, was measured. The results confirmed in situ high-performance capabilities of the proposed trans-tympanic microphone. PMID:26371007

  12. A fully implantable pacemaker for the mouse: from battery to wireless power.

    PubMed

    Laughner, Jacob I; Marrus, Scott B; Zellmer, Erik R; Weinheimer, Carla J; MacEwan, Matthew R; Cui, Sophia X; Nerbonne, Jeanne M; Efimov, Igor R

    2013-01-01

    Animal models have become a popular platform for the investigation of the molecular and systemic mechanisms of pathological cardiovascular physiology. Chronic pacing studies with implantable pacemakers in large animals have led to useful models of heart failure and atrial fibrillation. Unfortunately, molecular and genetic studies in these large animal models are often prohibitively expensive or not available. Conversely, the mouse is an excellent species for studying molecular mechanisms of cardiovascular disease through genetic engineering. However, the large size of available pacemakers does not lend itself to chronic pacing in mice. Here, we present the design for a novel, fully implantable wireless-powered pacemaker for mice capable of long-term (>30 days) pacing. This design is compared to a traditional battery-powered pacemaker to demonstrate critical advantages achieved through wireless inductive power transfer and control. Battery-powered and wireless-powered pacemakers were fabricated from standard electronic components in our laboratory. Mice (n = 24) were implanted with endocardial, battery-powered devices (n = 14) and epicardial, wireless-powered devices (n = 10). Wireless-powered devices were associated with reduced implant mortality and more reliable device function compared to battery-powered devices. Eight of 14 (57.1%) mice implanted with battery-powered pacemakers died following device implantation compared to 1 of 10 (10%) mice implanted with wireless-powered pacemakers. Moreover, device function was achieved for 30 days with the wireless-powered device compared to 6 days with the battery-powered device. The wireless-powered pacemaker system presented herein will allow electrophysiology studies in numerous genetically engineered mouse models as well as rapid pacing-induced heart failure and atrial arrhythmia in mice.

  13. A Fully Implantable Pacemaker for the Mouse: From Battery to Wireless Power

    PubMed Central

    Zellmer, Erik R.; Weinheimer, Carla J.; MacEwan, Matthew R.; Cui, Sophia X.; Nerbonne, Jeanne M.; Efimov, Igor R.

    2013-01-01

    Animal models have become a popular platform for the investigation of the molecular and systemic mechanisms of pathological cardiovascular physiology. Chronic pacing studies with implantable pacemakers in large animals have led to useful models of heart failure and atrial fibrillation. Unfortunately, molecular and genetic studies in these large animal models are often prohibitively expensive or not available. Conversely, the mouse is an excellent species for studying molecular mechanisms of cardiovascular disease through genetic engineering. However, the large size of available pacemakers does not lend itself to chronic pacing in mice. Here, we present the design for a novel, fully implantable wireless-powered pacemaker for mice capable of long-term (>30 days) pacing. This design is compared to a traditional battery-powered pacemaker to demonstrate critical advantages achieved through wireless inductive power transfer and control. Battery-powered and wireless-powered pacemakers were fabricated from standard electronic components in our laboratory. Mice (n = 24) were implanted with endocardial, battery-powered devices (n = 14) and epicardial, wireless-powered devices (n = 10). Wireless-powered devices were associated with reduced implant mortality and more reliable device function compared to battery-powered devices. Eight of 14 (57.1%) mice implanted with battery-powered pacemakers died following device implantation compared to 1 of 10 (10%) mice implanted with wireless-powered pacemakers. Moreover, device function was achieved for 30 days with the wireless-powered device compared to 6 days with the battery-powered device. The wireless-powered pacemaker system presented herein will allow electrophysiology studies in numerous genetically engineered mouse models as well as rapid pacing-induced heart failure and atrial arrhythmia in mice. PMID:24194832

  14. 21 CFR 882.5850 - Implanted spinal cord stimulator for bladder evacuation.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Implanted spinal cord stimulator for bladder....5850 Implanted spinal cord stimulator for bladder evacuation. (a) Identification. An implanted spinal... paraplegic patient who has a complete transection of the spinal cord and who is unable to empty his or...

  15. 21 CFR 882.5850 - Implanted spinal cord stimulator for bladder evacuation.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Implanted spinal cord stimulator for bladder....5850 Implanted spinal cord stimulator for bladder evacuation. (a) Identification. An implanted spinal... paraplegic patient who has a complete transection of the spinal cord and who is unable to empty his or...

  16. 21 CFR 882.5850 - Implanted spinal cord stimulator for bladder evacuation.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Implanted spinal cord stimulator for bladder....5850 Implanted spinal cord stimulator for bladder evacuation. (a) Identification. An implanted spinal... paraplegic patient who has a complete transection of the spinal cord and who is unable to empty his or...

  17. 21 CFR 882.5850 - Implanted spinal cord stimulator for bladder evacuation.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Implanted spinal cord stimulator for bladder....5850 Implanted spinal cord stimulator for bladder evacuation. (a) Identification. An implanted spinal... paraplegic patient who has a complete transection of the spinal cord and who is unable to empty his or...

  18. 21 CFR 882.5850 - Implanted spinal cord stimulator for bladder evacuation.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Implanted spinal cord stimulator for bladder....5850 Implanted spinal cord stimulator for bladder evacuation. (a) Identification. An implanted spinal... paraplegic patient who has a complete transection of the spinal cord and who is unable to empty his or...

  19. Numerical simulation of electrically stimulated osteogenesis in dental implants.

    PubMed

    Vanegas-Acosta, J C; Garzón-Alvarado, D A; Lancellotti, V

    2014-04-01

    Cell behavior and tissue formation are influenced by a static electric field (EF). Several protocols for EF exposure are aimed at increasing the rate of tissue recovery and reducing the healing times in wounds. However, the underlying mechanisms of the EF action on cells and tissues are still a matter of research. In this work we introduce a mathematical model for electrically stimulated osteogenesis at the bone-dental implant interface. The model describes the influence of the EF in the most critical biological processes leading to bone formation at the bone-dental implant interface. The numerical solution is able to reproduce the distribution of spatial-temporal patterns describing the influence of EF during blood clotting, osteogenic cell migration, granulation tissue formation, displacements of the fibrillar matrix, and formation of new bone. In addition, the model describes the EF-mediated cell behavior and tissue formation which lead to an increased osteogenesis in both smooth and rough implant surfaces. Since numerical results compare favorably with experimental evidence, the model can be used to predict the outcome of using electrostimulation in other types of wounds and tissues.

  20. Microchip-Embedded Capacitors for Implantable Neural Stimulators

    NASA Astrophysics Data System (ADS)

    Auciello, Orlando

    Miniaturization of microchips for implantation in the human body (e.g., microchip for the artificial retina to restore sight to people blinded by retina photoreceptors degeneration) requires the integration of high-capacitance (≥ 10 μF) energy-storage capacitors into the microchip. These capacitors would be based on high-dielectric constant layers, preferably made of materials that are bioinert (not affected by human body fluids) and are biocompatible (do not elicit adverse reactions in the human body). This chapter focuses on reviewing the work being done at Argonne National Laboratory (Materials Science Division and Center for Nanoscale Materials) to develop high-capacitance microchip-embedded capacitors based on novel high-K dielectric layers (TiAlOx or TiO2/Al2O3 superlattices). The microchip-embedded capacitor provides energy storage and electromagnetic signal coupling needed for neural stimulations. Advances in neural prostheses such as artificial retinas and cochlear implants require miniaturization of device size to minimize tissue damage and improve device/tissue interfaces in the human body. Therefore, development of microchip-embedded capacitors is critical to achieve full-implantable biomedical device miniaturization.

  1. Cephalad lead migration following spinal cord stimulation implantation.

    PubMed

    McGreevy, Kai; Williams, Kayode A; Christo, Paul J

    2012-01-01

    Lead migration (LM) is the most common complication after spinal cord stimulation (SCS). Although multiple reports of caudad LM have been described, cephalad LM has not been reported. Here we describe a case in which a stimulator lead migrates in the cephalad direction. A 60-year-old male with failed back surgery syndrome underwent SCS lead implantation via a dual lead approach to the top of vertebral body (VB) T9. A standard strain relief loop was used for each lead in the paramedian pocket. Postoperative testing revealed 100% paresthesia coverage of the painful areas. For the first 4 days, the patient continued to have excellent coverage; however, by the seventh day, the paresthesias ascended to above the nipple line. At the 2-week follow-up, cephalad migration of the left lead to the top of VB T1 was confirmed on fluoroscopy. The patient underwent successful lead revision in which a single paramedian incision technique was used to place extra sutures and a "figure-of-eight" strain relief loop. We provide the first case report of significant cephalad LM following SCS lead implantation. This migration can occur despite the use of current standard anchoring techniques. Additional investigation into the mechanism of such LM and lead-securing techniques is warranted. PMID:22270751

  2. Implantable direct current spinal fusion stimulators do not decrease implant-related infections in a rabbit model.

    PubMed

    Paryavi, Ebrahim; Yanko, Moshe; Jaffe, David; Nimmgadda, Naren; Nouveau, Jenna; Schiavone, Jason; Gilotra, Mohit; Gelb, Daniel; Ludwig, Steven C

    2014-05-01

    Electrical current detaches bacterial biofilm from implanted instrumentation. Hypothetically, this can decrease implant-related infection and allow retention of instrumentation in cases of postoperative wound infections. We conducted a prospective animal study to investigate whether a 60-μAmp implantable direct current (DC) fusion stimulator decreases implant-related infection rates in a multilevel fixed-implant postoperative spinal wound infection model in rabbits. Three dorsal sites, T13, L3, and L6, were instrumented in each rabbit. A 60-μAmp DC fusion stimulator was implanted in a subcutaneous pouch lateral to the instrumented sites, and leads were connected to 2 of 3 sites in each rabbit. All sites were inoculated with methicillin-sensitive Staphylococcus aureus (MSSA). Rabbits were euthanized at 7 days, and cultures were obtained from the surgical sites, including wound swab, bone, and implants. No significant reduction was observed in postoperative infection rates of bone or implant with 60-μAmp DC (95% and 77%, respectively) compared with no current (91% and 82%, respectively) (P > .5). No significant difference was observed in bacterial load (Ps = .25-.72) between sites receiving DC and control sites. Currently used 60-μAmp DC implantable spinal fusion stimulators do not significantly reduce the rate of postoperative implant-related spinal wound infections in a rabbit model. PMID:24839636

  3. Implantable direct current spinal fusion stimulators do not decrease implant-related infections in a rabbit model.

    PubMed

    Paryavi, Ebrahim; Yanko, Moshe; Jaffe, David; Nimmgadda, Naren; Nouveau, Jenna; Schiavone, Jason; Gilotra, Mohit; Gelb, Daniel; Ludwig, Steven C

    2014-05-01

    Electrical current detaches bacterial biofilm from implanted instrumentation. Hypothetically, this can decrease implant-related infection and allow retention of instrumentation in cases of postoperative wound infections. We conducted a prospective animal study to investigate whether a 60-μAmp implantable direct current (DC) fusion stimulator decreases implant-related infection rates in a multilevel fixed-implant postoperative spinal wound infection model in rabbits. Three dorsal sites, T13, L3, and L6, were instrumented in each rabbit. A 60-μAmp DC fusion stimulator was implanted in a subcutaneous pouch lateral to the instrumented sites, and leads were connected to 2 of 3 sites in each rabbit. All sites were inoculated with methicillin-sensitive Staphylococcus aureus (MSSA). Rabbits were euthanized at 7 days, and cultures were obtained from the surgical sites, including wound swab, bone, and implants. No significant reduction was observed in postoperative infection rates of bone or implant with 60-μAmp DC (95% and 77%, respectively) compared with no current (91% and 82%, respectively) (P > .5). No significant difference was observed in bacterial load (Ps = .25-.72) between sites receiving DC and control sites. Currently used 60-μAmp DC implantable spinal fusion stimulators do not significantly reduce the rate of postoperative implant-related spinal wound infections in a rabbit model.

  4. A single-channel implantable microstimulator for functional neuromuscular stimulation.

    PubMed

    Ziaie, B; Nardin, M D; Coghlan, A R; Najafi, K

    1997-10-01

    This paper describes a single-channel implantable microstimulator for functional neuromuscular stimulation. This device measures 2 x 2 x 10 mm3 and can be inserted into paralyzed muscle groups by expulsion from a hypodermic needle. Power and data to the device are supplied from outside by RF telemetry using an amplitude-modulated 2-MHz RF carrier generated using a high-efficiency class-E transmitter. The transmitted signal carries a 5-b address which selects one of the 32 possible microstimulators. The selected device then delivers up to 2 microC of charge store in a tantalum chip capacitor for up to 200 microseconds (10 mA) into loads of < 800 omega through a high-current thin-film iridium-oxide (IrOx) electrode (approximately 0.3 mm2 in area). A bi-CMOS receiver circuitry is used to: generate two regulated voltage supplies (4.5 and 9 V), recover a 2-MHz clock from the carrier, demodulate the address code, and activate the output current delivery circuitry upon the reception of an external command. The overall power dissipation of the receiver circuitry is 45-55 mW. The implant is hermetically packaged using a custom-made glass capsule.

  5. Bipolar implantable stimulator for long-term denervated-muscle experiments.

    PubMed

    Dennis, R G

    1998-03-01

    A micropower bipolar implantable stimulator has been developed and tested for long-term (four weeks-six months) use in experiments involving the stimulation of denervated skeletal muscle. Implantable stimulators are typically operated from a single lithium battery at 3 V. After the first week of denervation, stimulation of denervated muscles of rats requires voltages in the range of 6-12 V. The stimulator described can deliver voltages up to 15 V, with variable pulsewidth, frequency and duty cycle. All stimulation parameters are set prior to implantation by selection of appropriate resistors and capacitors. Each primary failure mode for implantable stimulators is addressed. Long-term reliability rates in excess of 95% are achievable if the construction details are followed closely. Methods for battery power management, circuit component selection, electrode construction and encapsulation are described in detail. This device is not intended for use in humans. PMID:9684464

  6. 21 CFR 882.5840 - Implanted intracerebral/subcortical stimulator for pain relief.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... pain relief. 882.5840 Section 882.5840 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Devices § 882.5840 Implanted intracerebral/subcortical stimulator for pain relief. (a) Identification. An implanted intracerebral/subcortical stimulator for pain relief is a device that applies electrical...

  7. 21 CFR 882.5840 - Implanted intracerebral/subcortical stimulator for pain relief.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... pain relief. 882.5840 Section 882.5840 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Devices § 882.5840 Implanted intracerebral/subcortical stimulator for pain relief. (a) Identification. An implanted intracerebral/subcortical stimulator for pain relief is a device that applies electrical...

  8. 21 CFR 882.5840 - Implanted intracerebral/subcortical stimulator for pain relief.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... pain relief. 882.5840 Section 882.5840 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Devices § 882.5840 Implanted intracerebral/subcortical stimulator for pain relief. (a) Identification. An implanted intracerebral/subcortical stimulator for pain relief is a device that applies electrical...

  9. 21 CFR 882.5840 - Implanted intracerebral/subcortical stimulator for pain relief.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... pain relief. 882.5840 Section 882.5840 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Devices § 882.5840 Implanted intracerebral/subcortical stimulator for pain relief. (a) Identification. An implanted intracerebral/subcortical stimulator for pain relief is a device that applies electrical...

  10. 21 CFR 882.5840 - Implanted intracerebral/subcortical stimulator for pain relief.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... pain relief. 882.5840 Section 882.5840 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Devices § 882.5840 Implanted intracerebral/subcortical stimulator for pain relief. (a) Identification. An implanted intracerebral/subcortical stimulator for pain relief is a device that applies electrical...

  11. Functional regeneration of severed peripheral nerve using an implantable electrical stimulator.

    PubMed

    Lee, Tae Hyung; Pan, Hui; Kim, In Sook; Hwang, Soon Jung; Kim, Sung June

    2010-01-01

    This paper presents functional regeneration of severed peripheral nerve using a polymer-based implantable electrical stimulator. A polyimide based conduit electrode was made by micro-fabrication and a stimulation chip was designed to generate biphasic current pulse for electrical stimulation. The stimulation chip was packaged with a battery using silicone elastomer, and integrated with the electrode. The implantable electrical stimulator was implanted in the rat sciatic nerve with 7 mm gap. The electrical stimulation was applied for periods of one, two and four weeks between the proximal and the distal nerve stumps. After four weeks of post-operations, the degree of regeneration was evaluated through walking track assessments and by measuring neural response of the regenerated nerve. Based on these results, electrical stimulation, especially for two weeks of stimulation, could accelerate functional regeneration of the severed nerve.

  12. Design and Evaluation of a Fully Implantable Control Unit for Blood Pumps

    PubMed Central

    Unthan, Kristin; Gräf, Felix; Laumen, Marco; Finocchiaro, Thomas; Sommer, Christoph; Lanmüller, Hermann; Steinseifer, Ulrich

    2015-01-01

    As the number of donor hearts is limited while more and more patients suffer from end stage biventricular heart failure, Total Artificial Hearts become a promising alternative to conventional treatment. While pneumatic devices sufficiently supply the patients with blood flow, the patient's quality of life is limited by the percutaneous pressure lines and the size of the external control unit. This paper describes the development of the control unit of the ReinHeart, a fully implantable Total Artificial Heart. General requirements for any implantable control unit are defined from a technical and medical point of view: necessity of a Transcutaneous Energy Transmission, autonomous operation, safety, geometry, and efficiency. Based on the requirements, a prototype is designed; it incorporates a LiFePo4 battery pack with charger, a rectifier for transcutaneous energy transmission, the motor's driver electronics, and a microcontroller which monitors and controls all functions. In validation tests, the control unit demonstrated a stable operation on TET and battery supply and a safe switching from one supply to the other. The overall mean efficiency is 14% on TET and 22% on battery supply. The control unit is suitable for chronic animal trials of the ReinHeart. PMID:26583095

  13. Design and Evaluation of a Fully Implantable Control Unit for Blood Pumps.

    PubMed

    Unthan, Kristin; Gräf, Felix; Laumen, Marco; Finocchiaro, Thomas; Sommer, Christoph; Lanmüller, Hermann; Steinseifer, Ulrich

    2015-01-01

    As the number of donor hearts is limited while more and more patients suffer from end stage biventricular heart failure, Total Artificial Hearts become a promising alternative to conventional treatment. While pneumatic devices sufficiently supply the patients with blood flow, the patient's quality of life is limited by the percutaneous pressure lines and the size of the external control unit. This paper describes the development of the control unit of the ReinHeart, a fully implantable Total Artificial Heart. General requirements for any implantable control unit are defined from a technical and medical point of view: necessity of a Transcutaneous Energy Transmission, autonomous operation, safety, geometry, and efficiency. Based on the requirements, a prototype is designed; it incorporates a LiFePo4 battery pack with charger, a rectifier for transcutaneous energy transmission, the motor's driver electronics, and a microcontroller which monitors and controls all functions. In validation tests, the control unit demonstrated a stable operation on TET and battery supply and a safe switching from one supply to the other. The overall mean efficiency is 14% on TET and 22% on battery supply. The control unit is suitable for chronic animal trials of the ReinHeart. PMID:26583095

  14. Carina® and Esteem®: A Systematic Review of Fully Implantable Hearing Devices

    PubMed Central

    Pulcherio, Janaina Oliveira Bentivi; Bittencourt, Aline Gomes; Burke, Patrick Rademaker; Monsanto, Rafael da Costa; de Brito, Rubens; Tsuji, Robinson Koji; Bento, Ricardo Ferreira

    2014-01-01

    Objective To review the outcomes of the fully implantable middle ear devices Carina and Esteem regarding the treatment of hearing loss. Data Sources PubMed, Embase, Scielo, and Cochrane Library databases were searched. Study Selection Abstracts of 77 citations were screened, and 43 articles were selected for full review. From those, 22 studies and two literature reviews in English directly demonstrating the results of Carina and Esteem were included. Data Extraction There were a total of 244 patients ranging from 18 to 88 years. One hundred and 10 patients were implanted with Carina and with 134 Esteem. There were registered 92 males and 67 females. Five studies provided no information about patients’ age or gender. From the data available, the follow-up ranged from 2 to 29.4 months. Data Synthesis The comparison of the results about word recognition is difficult as there was no standardization of measurement. The results were obtained from various sound intensities and different frequencies. The outcomes comparing to conventional HAs were conflicting. Nevertheless, all results comparing to unaided condition showed improvement and showed a subjective improvement of quality of life. Conclusion There are still some problems to be solved, mainly related to device functioning and price. Due to the relatively few publications available and small sample sizes, we must be careful in extrapolating these results to a broader population. Additionally, none of all these studies represented level high levels of evidence (i.e. randomized controlled trials). PMID:25329463

  15. Vestibular implantation and longitudinal electrical stimulation of the semicircular canal afferents in human subjects.

    PubMed

    Phillips, James O; Ling, Leo; Nie, Kaibao; Jameyson, Elyse; Phillips, Christopher M; Nowack, Amy L; Golub, Justin S; Rubinstein, Jay T

    2015-06-01

    Animal experiments and limited data in humans suggest that electrical stimulation of the vestibular end organs could be used to treat loss of vestibular function. In this paper we demonstrate that canal-specific two-dimensionally (2D) measured eye velocities are elicited from intermittent brief 2 s biphasic pulse electrical stimulation in four human subjects implanted with a vestibular prosthesis. The 2D measured direction of the slow phase eye movements changed with the canal stimulated. Increasing pulse current over a 0-400 μA range typically produced a monotonic increase in slow phase eye velocity. The responses decremented or in some cases fluctuated over time in most implanted canals but could be partially restored by changing the return path of the stimulation current. Implantation of the device in Meniere's patients produced hearing and vestibular loss in the implanted ear. Electrical stimulation was well tolerated, producing no sensation of pain, nausea, or auditory percept with stimulation that elicited robust eye movements. There were changes in slow phase eye velocity with current and over time, and changes in electrically evoked compound action potentials produced by stimulation and recorded with the implanted device. Perceived rotation in subjects was consistent with the slow phase eye movements in direction and scaled with stimulation current in magnitude. These results suggest that electrical stimulation of the vestibular end organ in human subjects provided controlled vestibular inputs over time, but in Meniere's patients this apparently came at the cost of hearing and vestibular function in the implanted ear.

  16. A novel closed-loop electromechanical stimulator to enhance osseointegration with immediate loading of dental implant restorations.

    PubMed

    Meswania, I M; Bousdras, V A; Ahir, S P; Cunningham, J L; Blunn, G W; Goodship, A E

    2010-10-01

    The degree of osseomechanical integration of dental implants is acutely sensitive to their mechanical environment. Bone, both as a tissue and structure, adapts its mass and architecture in response to loading conditions. Therefore, application of predefined controlled loads may be considered as a treatment option to promote early maturation of bone/implant interface prior to or in conjunction with crown/prosthesis attachment. Although many studies have established that the magnitude, rate of the applied strain, and frequency have significant effects on the osteogenic response, the actual specific relationships between strain parameters and frequency have not yet been fully defined. The purpose of this study was to develop a stimulator to apply defined mechanical stimuli to individual dental implants in vivo immediately after implantation, exploring the hypothesis that immediate controlled loading could enhance implant integration. An electromechanical device was developed, based on load values obtained using a two-dimensional finite element analysis of the bone/implant interface generating 1000 to 4000 pe and operated at 30 and 3 Hz respectively. The device was then tested in a cadaveric pig mandible, and periosteal bone surface strains were recorded for potential future comparison with a three-dimensional finite element model to determine loading regimens to optimize interface strains and iterate the device for clinical use.

  17. Immunologic stimulation of T lymphocytes by silica after use of silicone mammary implants.

    PubMed

    Smalley, D L; Shanklin, D R; Hall, M F; Stevens, M V; Hanissian, A

    1995-03-01

    Difficulties in showing the biologic activity of silicones in vitro have contributed to the controversy over effects of silicone mammary implants in vivo. We adapted a standard lymphocyte stimulation test to detect evidence of cellular immunity in patients with silicone gel implants. Initially, lymphocytes were harvested from 70 implant patients, 76 normal controls without implants or symptoms, and 18 patients with classic rheumatic disorders and without a history of silicone implants. The harvested lymphocytes were stimulated with PWM, PHA, Con A, and pharmaceutical grade colloidal silicon dioxide (silica). Implant patients showed increased SI compared to controls and those with rheumatic disorders. The mean SI of implant patients was 195.0 +/- 19.3, 18-fold that of normal controls (< 0.0001). Patients with rheumatic disease showed the same SI as controls (P = 0.3577). A follow-up study included 220 normal controls without implants, 942 silicone gel implant patients with demonstrable rheumatic symptoms, and 34 implant patients without symptoms at the time of the study. The average SI for the 220 normal controls was 10.0 +/- 0.41. Among the symptomatic implant women, 860 (91.3%) had SI significantly above those of the normal controls. Of these, 171 (18.2%) had SI between 25 and 50, 316 (33.5%) had SI between 50 and 100, and 373 (39.6%) had SI over 100. The data presented confirms that silicone implant patients respond immunologically to the silicon dioxide contained in mammary prostheses.

  18. 21 CFR 882.5830 - Implanted diaphragmatic/phrenic nerve stimulator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... which an abnormally low amount of air enters the lungs) caused by brain stem disease, high cervical spinal cord injury, or chronic lung disease. The stimulator consists of an implanted receiver...

  19. 21 CFR 882.5830 - Implanted diaphragmatic/phrenic nerve stimulator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... which an abnormally low amount of air enters the lungs) caused by brain stem disease, high cervical spinal cord injury, or chronic lung disease. The stimulator consists of an implanted receiver...

  20. A Fully Implantable, Programmable and Multimodal Neuroprocessor for Wireless, Cortically Controlled Brain-Machine Interface Applications

    PubMed Central

    Zhang, Fei; Aghagolzadeh, Mehdi; Oweiss, Karim

    2012-01-01

    Reliability, scalability and clinical viability are of utmost importance in the design of wireless Brain Machine Interface systems (BMIs). This paper reports on the design and implementation of a neuroprocessor for conditioning raw extracellular neural signals recorded through microelectrode arrays chronically implanted in the brain of awake behaving rats. The neuroprocessor design exploits a sparse representation of the neural signals to combat the limited wireless telemetry bandwidth. We demonstrate a multimodal processing capability (monitoring, compression, and spike sorting) inherent in the neuroprocessor to support a wide range of scenarios in real experimental conditions. A wireless transmission link with rate-dependent compression strategy is shown to preserve information fidelity in the neural data. At 32 channels, the neuroprocessor has been fully implemented on a 5mm×5mm nano-FPGA, and the prototyping resulted in 5.19 mW power consumption, bringing its performance within the power-size constraints for clinical use. The optimal design for compression and sorting performance was evaluated for multiple sampling frequencies, wavelet basis choice and power consumption. PMID:23050029

  1. Combined use of transcranial magnetic stimulation and metal electrode implants: a theoretical assessment of safety considerations

    NASA Astrophysics Data System (ADS)

    Golestanirad, Laleh; Rouhani, Hossein; Elahi, Behzad; Shahim, Kamal; Chen, Robert; Mosig, Juan R.; Pollo, Claudio; Graham, Simon J.

    2012-12-01

    This paper provides a theoretical assessment of the safety considerations encountered in the simultaneous use of transcranial magnetic stimulation (TMS) and neurological interventions involving implanted metallic electrodes, such as electrocorticography. Metal implants are subject to magnetic forces due to fast alternating magnetic fields produced by the TMS coil. The question of whether the mechanical movement of the implants leads to irreversible damage of brain tissue is addressed by an electromagnetic simulation which quantifies the magnitude of imposed magnetic forces. The assessment is followed by a careful mechanical analysis determining the maximum tolerable force which does not cause irreversible tissue damage. Results of this investigation provide useful information on the range of TMS stimulator output powers which can be safely used in patients having metallic implants. It is shown that conventional TMS applications can be considered safe when applied on patients with typical electrode implants as the induced stress in the brain tissue remains well below the limit of tissue damage.

  2. CUSTOM-FIT RADIOLUCENT CRANIAL IMPLANTS FOR NEUROPHYSIOLOGICAL RECORDING AND STIMULATION

    PubMed Central

    Mulliken, Grant H; Bichot, Narcisse P; Ghadooshahy, Azriel; Sharma, Jitendra; Kornblith, Simon; Philcock, Michael; Desimone, Robert

    2015-01-01

    Background Recording and manipulating neural activity in awake behaving animal models requires long-term implantation of cranial implants that must address a variety of design considerations, which include preventing infection, minimizing tissue damage, mechanical strength of the implant, and MRI compatibility. New Method Here we address these issues by designing legless, custom-fit cranial implants using structural MRI-based reconstruction of the skull and that are made from carbon-reinforced PEEK. Results We report several novel custom-fit radiolucent implant designs, which include a legless recording chamber, a legless stimulation chamber, a multi-channel microdrive and a head post. The fit to the skull was excellent in all cases, with no visible gaps between the base of the implants and the skull. The wound margin was minimal in size and showed no sign of infection or skin recession. Comparison with Existing Methods Cranial implants used for neurophysiological investigation in awake behaving animals often employ methyl methacrylate (MMA) to serve as a bonding agent to secure the implant to the skull. Other designs rely on radially extending legs to secure the implant. Both of these methods have significant drawbacks. MMA is toxic to bone and frequently leads to infection while radially extending legs cause the skin to recede away from the implant, ultimately exposing bone and proliferating granulation tissue. Conclusions These radiolucent implants constitute a set of technologies suitable for reliable long-term recording, which minimize infection and tissue damage. PMID:25542350

  3. Vestibular implantation and longitudinal electrical stimulation of the semicircular canal afferents in human subjects

    PubMed Central

    Ling, Leo; Nie, Kaibao; Jameyson, Elyse; Phillips, Christopher M.; Nowack, Amy L.; Golub, Justin S.; Rubinstein, Jay T.

    2015-01-01

    Animal experiments and limited data in humans suggest that electrical stimulation of the vestibular end organs could be used to treat loss of vestibular function. In this paper we demonstrate that canal-specific two-dimensionally (2D) measured eye velocities are elicited from intermittent brief 2 s biphasic pulse electrical stimulation in four human subjects implanted with a vestibular prosthesis. The 2D measured direction of the slow phase eye movements changed with the canal stimulated. Increasing pulse current over a 0–400 μA range typically produced a monotonic increase in slow phase eye velocity. The responses decremented or in some cases fluctuated over time in most implanted canals but could be partially restored by changing the return path of the stimulation current. Implantation of the device in Meniere's patients produced hearing and vestibular loss in the implanted ear. Electrical stimulation was well tolerated, producing no sensation of pain, nausea, or auditory percept with stimulation that elicited robust eye movements. There were changes in slow phase eye velocity with current and over time, and changes in electrically evoked compound action potentials produced by stimulation and recorded with the implanted device. Perceived rotation in subjects was consistent with the slow phase eye movements in direction and scaled with stimulation current in magnitude. These results suggest that electrical stimulation of the vestibular end organ in human subjects provided controlled vestibular inputs over time, but in Meniere's patients this apparently came at the cost of hearing and vestibular function in the implanted ear. PMID:25652917

  4. Effects of Vestibular Prosthesis Electrode Implantation and Stimulation on Hearing in Rhesus Monkeys

    PubMed Central

    Dai, Chenkai; Fridman, Gene Y.; Della Santina, Charles C.

    2011-01-01

    To investigate the effects of vestibular prosthesis electrode implantation and activation on hearing in rhesus monkeys, we measured auditory brainstem responses (ABR) and distortion product otoacoustic emissions (DPOAE) in four rhesus monkeys before and after unilateral implantation of vestibular prosthesis electrodes in each of 3 left semicircular canals (SCC). Each of the 3 left SCCs were implanted with electrodes via a transmastoid approach. Right ears, which served as controls, were not surgically manipulated. Hearing tests were conducted before implantation (BI) and then 4 weeks post implantation both without electrical stimulation (NS) and with electrical stimulation (S). During the latter condition, prosthetic electrical stimuli encoding 3 dimensions of head angular velocity were delivered to the 3 ampullary branches of the left vestibular nerve via each of 3 electrode pairs of a multichannel vestibular prosthesis. Electrical stimuli comprised charge-balanced biphasic pulses at a baseline rate of 94 pulses/sec, with pulse frequency modulated from 48–222 pulses/s by head angular velocity. ABR hearing thresholds to clicks and tone pips at 1, 2, and 4 kHz increased by 5–10 dB from BI to NS and increased another ~5 dB from NS to S in implanted ears. No significant change was seen in right ears. DPOAE amplitudes decreased by 2–14 dB from BI to NS in implanted ears. There was a slight but insignificant decrease of DPOAE amplitude and a corresponding increase of DPOAE/Noise floor ratio between NS and S in implanted ears. Vestibular prosthesis electrode implantation and activation have small but measurable effects on hearing in rhesus monkeys. Coupled with the clinical observation that patients with cochlear implants only rarely exhibit signs of vestibular injury or spurious vestibular nerve stimulation, these results suggest that although implantation and activation of multichannel vestibular prosthesis electrodes in human will carry a risk of hearing loss

  5. Psychophysics, fitting, and signal processing for combined hearing aid and cochlear implant stimulation.

    PubMed

    Francart, Tom; McDermott, Hugh J

    2013-01-01

    The addition of acoustic stimulation to electric stimulation via a cochlear implant has been shown to be advantageous for speech perception in noise, sound quality, music perception, and sound source localization. However, the signal processing and fitting procedures of current cochlear implants and hearing aids were developed independently, precluding several potential advantages of bimodal stimulation, such as improved sound source localization and binaural unmasking of speech in noise. While there is a large and increasing population of implantees who use a hearing aid, there are currently no generally accepted fitting methods for this configuration. It is not practical to fit current commercial devices to achieve optimal binaural loudness balance or optimal binaural cue transmission for arbitrary signals and levels. There are several promising experimental signal processing systems specifically designed for bimodal stimulation. In this article, basic psychophysical studies with electric acoustic stimulation are reviewed, along with the current state of the art in fitting, and experimental signal processing techniques for electric acoustic stimulation.

  6. Non-penetrating round window electrode stimulation for tinnitus therapy followed by cochlear implantation.

    PubMed

    Wenzel, Gentiana I; Sarnes, Petra; Warnecke, Athanasia; Stöver, Timo; Jäger, Burkard; Lesinski-Schiedat, Anke; Lenarz, Thomas

    2015-11-01

    One main theory behind the origin of tinnitus is based on the idea that alterations of the spontaneous electrical activity within the auditory system lead to abnormal firing patterns in the affected nervous structures [1]. A possible therapeutic option is the use of electrical stimulation of the auditory nerve for the recovery or at least limitation of the abnormal firing pattern to a level that can be easily tolerated by the patient. The Tinnelec Implant consists of a single non-penetrating stimulation electrode connected to a Neurelec cochlear implant system. As a first feasibility study, before starting implantations in hearing patients, we thought to assess the potential of the Tinnelec stimulation to treat tinnitus in unilateral deaf patients, analysing hereby its effectivity and risks. Three patients suffering from unilateral tinnitus resistant to pharmacological treatment and ipsilateral severe to profound sensorineural hearing loss/deafness were implanted with a Tinnelec system between September 2007 and July 2008, at the ENT Department of Hannover Medical School. The stimulation strategy was chosen to induce alleviation of the tinnitus through suppression, masking and/or habituation and the response of each patient on the treatment was monitored using a visual analogue scale (VAS) on loudness and annoyance of tinnitus, mood of the patient, as well as the tinnitus handicap inventory (THI). All patients had a benefit from the electrical stimulation for their tinnitus (THI-score improvement of 20-70), however, not all participants profited from the Tinnelec system in same way and degree. In one patient, despite good results, the device had to be replaced with a conventional cochlear implant because of Tinnelec-independent increase in hearing loss on the contralateral ear. Additionally, due to the extension of cochlear implant indications, the devices of the other two patients have been meanwhile replaced with a conventional cochlear implant to benefit

  7. Non-penetrating round window electrode stimulation for tinnitus therapy followed by cochlear implantation.

    PubMed

    Wenzel, Gentiana I; Sarnes, Petra; Warnecke, Athanasia; Stöver, Timo; Jäger, Burkard; Lesinski-Schiedat, Anke; Lenarz, Thomas

    2015-11-01

    One main theory behind the origin of tinnitus is based on the idea that alterations of the spontaneous electrical activity within the auditory system lead to abnormal firing patterns in the affected nervous structures [1]. A possible therapeutic option is the use of electrical stimulation of the auditory nerve for the recovery or at least limitation of the abnormal firing pattern to a level that can be easily tolerated by the patient. The Tinnelec Implant consists of a single non-penetrating stimulation electrode connected to a Neurelec cochlear implant system. As a first feasibility study, before starting implantations in hearing patients, we thought to assess the potential of the Tinnelec stimulation to treat tinnitus in unilateral deaf patients, analysing hereby its effectivity and risks. Three patients suffering from unilateral tinnitus resistant to pharmacological treatment and ipsilateral severe to profound sensorineural hearing loss/deafness were implanted with a Tinnelec system between September 2007 and July 2008, at the ENT Department of Hannover Medical School. The stimulation strategy was chosen to induce alleviation of the tinnitus through suppression, masking and/or habituation and the response of each patient on the treatment was monitored using a visual analogue scale (VAS) on loudness and annoyance of tinnitus, mood of the patient, as well as the tinnitus handicap inventory (THI). All patients had a benefit from the electrical stimulation for their tinnitus (THI-score improvement of 20-70), however, not all participants profited from the Tinnelec system in same way and degree. In one patient, despite good results, the device had to be replaced with a conventional cochlear implant because of Tinnelec-independent increase in hearing loss on the contralateral ear. Additionally, due to the extension of cochlear implant indications, the devices of the other two patients have been meanwhile replaced with a conventional cochlear implant to benefit

  8. New cosurface capacitive stimulators for the development of active osseointegrative implantable devices.

    PubMed

    Soares Dos Santos, Marco P; Marote, Ana; Santos, T; Torrão, João; Ramos, A; Simões, José A O; da Cruz E Silva, Odete A B; Furlani, Edward P; Vieira, Sandra I; Ferreira, Jorge A F

    2016-01-01

    Non-drug strategies based on biophysical stimulation have been emphasized for the treatment and prevention of musculoskeletal conditions. However, to date, an effective stimulation system for intracorporeal therapies has not been proposed. This is particularly true for active intramedullary implants that aim to optimize osseointegration. The increasing demand for these implants, particularly for hip and knee replacements, has driven the design of innovative stimulation systems that are effective in bone-implant integration. In this paper, a new cosurface-based capacitive system concept is proposed for the design of implantable devices that deliver controllable and personalized electric field stimuli to target tissues. A prototype architecture of this system was constructed for in vitro tests, and its ability to deliver controllable stimuli was numerically analyzed. Successful results were obtained for osteoblastic proliferation and differentiation in the in vitro tests. This work provides, for the first time, a design of a stimulation system that can be embedded in active implantable devices for controllable bone-implant integration and regeneration. The proposed cosurface design holds potential for the implementation of novel and innovative personalized stimulatory therapies based on the delivery of electric fields to bone cells. PMID:27456818

  9. New cosurface capacitive stimulators for the development of active osseointegrative implantable devices

    PubMed Central

    Soares dos Santos, Marco P.; Marote, Ana; Santos, T.; Torrão, João; Ramos, A.; Simões, José A. O.; da Cruz e Silva, Odete A. B.; Furlani, Edward P.; Vieira, Sandra I.; Ferreira, Jorge A. F.

    2016-01-01

    Non-drug strategies based on biophysical stimulation have been emphasized for the treatment and prevention of musculoskeletal conditions. However, to date, an effective stimulation system for intracorporeal therapies has not been proposed. This is particularly true for active intramedullary implants that aim to optimize osseointegration. The increasing demand for these implants, particularly for hip and knee replacements, has driven the design of innovative stimulation systems that are effective in bone-implant integration. In this paper, a new cosurface-based capacitive system concept is proposed for the design of implantable devices that deliver controllable and personalized electric field stimuli to target tissues. A prototype architecture of this system was constructed for in vitro tests, and its ability to deliver controllable stimuli was numerically analyzed. Successful results were obtained for osteoblastic proliferation and differentiation in the in vitro tests. This work provides, for the first time, a design of a stimulation system that can be embedded in active implantable devices for controllable bone-implant integration and regeneration. The proposed cosurface design holds potential for the implementation of novel and innovative personalized stimulatory therapies based on the delivery of electric fields to bone cells. PMID:27456818

  10. Possibilities of implanted control in stimulated light scattering experiments

    NASA Astrophysics Data System (ADS)

    Lazarenko, Anatoliy G.; Andreev, Alexandr N.; Kanaev, Andrey V.

    2004-09-01

    Some possibilities of simple and thus reliable schemes of experiment "self-control" exploiting intrinsic features of studied non-linear phenomena like wave front reversal under stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS) and coherent anti-Stokes Raman scattering (CARS) rather than outer sensors and controls are described. The schemes discussed provide input signal dynamic region broadening in stimulated scattering converters and angle of synchronism self-tuning while two frequency pumping.

  11. Characterization of a Polymer-Based, Fully Organic Prosthesis for Implantation into the Subretinal Space of the Rat.

    PubMed

    Antognazza, Maria Rosa; Di Paolo, Mattia; Ghezzi, Diego; Mete, Maurizio; Di Marco, Stefano; Maya-Vetencourt, José Fernando; Maccarone, Rita; Desii, Andrea; Di Fonzo, Fabio; Bramini, Mattia; Russo, Angela; Laudato, Lucia; Donelli, Ilaria; Cilli, Michele; Freddi, Giuliano; Pertile, Grazia; Lanzani, Guglielmo; Bisti, Silvia; Benfenati, Fabio

    2016-09-01

    Replacement strategies arise as promising approaches in case of inherited retinal dystrophies leading to blindness. A fully organic retinal prosthesis made of conjugated polymers layered onto a silk fibroin substrate is engineered. First, the biophysical and surface properties are characterized; then, the long-term biocompatibility is assessed after implantation of the organic device in the subretinal space of 3-months-old rats for a period of five months. The results indicate a good stability of the subretinal implants over time, with preservation of the physical properties of the polymeric layer and a tight contact with the outer retina. Immunoinflammatory markers detect only a modest tissue reaction to the surgical insult and the foreign body that peaks shortly after surgery and progressively decreases with time to normal levels at five months after implantation. Importantly, the integrity of the polymeric layer in direct contact with the retinal tissue is preserved after five months of implantation. The recovery of the foreign-body tissue reaction is also associated with a normal b-wave in the electroretinographic response. The results demonstrate that the device implanted in nondystrophic eyes is well tolerated, highly biocompatible, and suitable as retinal prosthesis in case of photoreceptor degeneration. PMID:27240295

  12. A fully integrated wireless system for intracranial direct cortical stimulation, real-time electrocorticography data transmission, and smart cage for wireless battery recharge.

    PubMed

    Piangerelli, Marco; Ciavarro, Marco; Paris, Antonino; Marchetti, Stefano; Cristiani, Paolo; Puttilli, Cosimo; Torres, Napoleon; Benabid, Alim Louis; Romanelli, Pantaleo

    2014-01-01

    Wireless transmission of cortical signals is an essential step to improve the safety of epilepsy procedures requiring seizure focus localization and to provide chronic recording of brain activity for Brain Computer Interface (BCI) applications. Our group developed a fully implantable and externally rechargeable device, able to provide wireless electrocorticographic (ECoG) recording and cortical stimulation (CS). The first prototype of a wireless multi-channel very low power ECoG system was custom-designed to be implanted on non-human primates. The device, named ECOGIW-16E, is housed in a compact hermetically sealed Polyether ether ketone (PEEK) enclosure, allowing seamless battery recharge. ECOGIW-16E is recharged in a wireless fashion using a special cage designed to facilitate the recharge process in monkeys and developed in accordance with guidelines for accommodation of animals by Council of Europe (ETS123). The inductively recharging cage is made up of nylon and provides a thoroughly novel experimental setting on freely moving animals. The combination of wireless cable-free ECoG and external seamless battery recharge solves the problems and shortcomings caused by the presence of cables leaving the skull, providing a safer and easier way to monitor patients and to perform ECoG recording on primates. Data transmission exploits the newly available Medical Implant Communication Service band (MICS): 402-405 MHz. ECOGIW-16E was implanted over the left sensorimotor cortex of a macaca fascicularis to assess the feasibility of wireless ECoG monitoring and brain mapping through CS. With this device, we were able to record the everyday life ECoG signal from a monkey and to deliver focal brain stimulation with movement elicitation.

  13. A fully integrated wireless system for intracranial direct cortical stimulation, real-time electrocorticography data transmission, and smart cage for wireless battery recharge.

    PubMed

    Piangerelli, Marco; Ciavarro, Marco; Paris, Antonino; Marchetti, Stefano; Cristiani, Paolo; Puttilli, Cosimo; Torres, Napoleon; Benabid, Alim Louis; Romanelli, Pantaleo

    2014-01-01

    Wireless transmission of cortical signals is an essential step to improve the safety of epilepsy procedures requiring seizure focus localization and to provide chronic recording of brain activity for Brain Computer Interface (BCI) applications. Our group developed a fully implantable and externally rechargeable device, able to provide wireless electrocorticographic (ECoG) recording and cortical stimulation (CS). The first prototype of a wireless multi-channel very low power ECoG system was custom-designed to be implanted on non-human primates. The device, named ECOGIW-16E, is housed in a compact hermetically sealed Polyether ether ketone (PEEK) enclosure, allowing seamless battery recharge. ECOGIW-16E is recharged in a wireless fashion using a special cage designed to facilitate the recharge process in monkeys and developed in accordance with guidelines for accommodation of animals by Council of Europe (ETS123). The inductively recharging cage is made up of nylon and provides a thoroughly novel experimental setting on freely moving animals. The combination of wireless cable-free ECoG and external seamless battery recharge solves the problems and shortcomings caused by the presence of cables leaving the skull, providing a safer and easier way to monitor patients and to perform ECoG recording on primates. Data transmission exploits the newly available Medical Implant Communication Service band (MICS): 402-405 MHz. ECOGIW-16E was implanted over the left sensorimotor cortex of a macaca fascicularis to assess the feasibility of wireless ECoG monitoring and brain mapping through CS. With this device, we were able to record the everyday life ECoG signal from a monkey and to deliver focal brain stimulation with movement elicitation. PMID:25202300

  14. A Fully Integrated Wireless System for Intracranial Direct Cortical Stimulation, Real-Time Electrocorticography Data Transmission, and Smart Cage for Wireless Battery Recharge

    PubMed Central

    Piangerelli, Marco; Ciavarro, Marco; Paris, Antonino; Marchetti, Stefano; Cristiani, Paolo; Puttilli, Cosimo; Torres, Napoleon; Benabid, Alim Louis; Romanelli, Pantaleo

    2014-01-01

    Wireless transmission of cortical signals is an essential step to improve the safety of epilepsy procedures requiring seizure focus localization and to provide chronic recording of brain activity for Brain Computer Interface (BCI) applications. Our group developed a fully implantable and externally rechargeable device, able to provide wireless electrocorticographic (ECoG) recording and cortical stimulation (CS). The first prototype of a wireless multi-channel very low power ECoG system was custom-designed to be implanted on non-human primates. The device, named ECOGIW-16E, is housed in a compact hermetically sealed Polyether ether ketone (PEEK) enclosure, allowing seamless battery recharge. ECOGIW-16E is recharged in a wireless fashion using a special cage designed to facilitate the recharge process in monkeys and developed in accordance with guidelines for accommodation of animals by Council of Europe (ETS123). The inductively recharging cage is made up of nylon and provides a thoroughly novel experimental setting on freely moving animals. The combination of wireless cable-free ECoG and external seamless battery recharge solves the problems and shortcomings caused by the presence of cables leaving the skull, providing a safer and easier way to monitor patients and to perform ECoG recording on primates. Data transmission exploits the newly available Medical Implant Communication Service band (MICS): 402–405 MHz. ECOGIW-16E was implanted over the left sensorimotor cortex of a macaca fascicularis to assess the feasibility of wireless ECoG monitoring and brain mapping through CS. With this device, we were able to record the everyday life ECoG signal from a monkey and to deliver focal brain stimulation with movement elicitation. PMID:25202300

  15. Evaluation of focused multipolar stimulation for cochlear implants in acutely deafened cats

    NASA Astrophysics Data System (ADS)

    George, Shefin S.; Wise, Andrew K.; Shivdasani, Mohit N.; Shepherd, Robert K.; Fallon, James B.

    2014-12-01

    Objective. The conductive nature of the fluids and tissues of the cochlea can lead to broad activation of spiral ganglion neurons using contemporary cochlear implant stimulation configurations such as monopolar (MP) stimulation. The relatively poor spatial selectivity is thought to limit implant performance, particularly in noisy environments. Several current focusing techniques have been proposed to reduce the spread of activation with the aim towards achieving improved clinical performance. Approach. The present research evaluated the efficacy of focused multipolar (FMP) stimulation, a relatively new focusing technique in the cochlea, and compared its efficacy to both MP stimulation and tripolar (TP) stimulation. The spread of neural activity across the inferior colliculus (IC), measured by recording the spatial tuning curve, was used as a measure of spatial selectivity. Adult cats (n = 6) were acutely deafened and implanted with an intracochlear electrode array before multi-unit responses were recorded across the cochleotopic gradient of the contralateral IC. Recordings were made in response to acoustic and electrical stimulation using the MP, TP and FMP configurations. Main results. FMP and TP stimulation resulted in greater spatial selectivity than MP stimulation. However, thresholds were significantly higher (p < 0.001) for FMP and TP stimulation compared to MP stimulation. There were no differences found in spatial selectivity and threshold between FMP and TP stimulation. Significance. The greater spatial selectivity of FMP and TP stimulation would be expected to result in improved clinical performance. However, further research will be required to demonstrate the efficacy of these modes of stimulation after longer durations of deafness.

  16. Cochlear Implant Stimulation of a Hearing Ear Generates Separate Electrophonic and Electroneural Responses

    PubMed Central

    Baumhoff, Peter; Kral, Andrej

    2016-01-01

    Electroacoustic stimulation in subjects with residual hearing is becoming more widely used in clinical practice. However, little is known about the properties of electrically induced responses in the hearing cochlea. In the present study, normal-hearing guinea pig cochleae underwent cochlear implantation through a cochleostomy without significant loss of hearing. Using recordings of unit activity in the midbrain, we were able to investigate the excitation patterns throughout the tonotopic field determined by acoustic stimulation. With the cochlear implant and the midbrain multielectrode arrays left in place, the ears were pharmacologically deafened and electrical stimulation was repeated in the deafened condition. The results demonstrate that, in addition to direct neuronal (electroneuronal) stimulation, in the hearing cochlea excitation of the hair cells occurs (“electrophonic responses”) at the cochlear site corresponding to the dominant temporal frequency components of the electrical stimulus, provided these are < 12 kHz. The slope of the rate–level functions of the neurons in the deafened condition was steeper and the firing rate was higher than in the hearing condition at those sites that were activated in the two conditions. Finally, in a monopolar stimulation configuration, the differences between hearing status conditions were smaller than in the narrower (bipolar) configurations. SIGNIFICANCE STATEMENT Stimulation with cochlear implants and hearing aids is becoming more widely clinically used in subjects with residual hearing. The neurophysiological characteristics underlying electroacoustic stimulation and the mechanism of its benefit remain unclear. The present study directly demonstrates that cochlear implantation does not interfere with the normal mechanical and physiological function of the cochlea. For the first time, it double-dissociates the electrical responses of hair cells (electrophonic responses) from responses of the auditory nerve

  17. Implantable power generation system utilizing muscle contractions excited by electrical stimulation.

    PubMed

    Sahara, Genta; Hijikata, Wataru; Tomioka, Kota; Shinshi, Tadahiko

    2016-06-01

    An implantable power generation system driven by muscle contractions for supplying power to active implantable medical devices, such as pacemakers and neurostimulators, is proposed. In this system, a muscle is intentionally contracted by an electrical stimulation in accordance with the demands of the active implantable medical device for electrical power. The proposed system, which comprises a small electromagnetic induction generator, electrodes with an electrical circuit for stimulation and a transmission device to convert the linear motion of the muscle contractions into rotational motion for the magneto rotor, generates electrical energy. In an ex vivo demonstration using the gastrocnemius muscle of a toad, which was 28 mm in length and weighed 1.3 g, the electrical energy generated by the prototype exceeded the energy consumed for electrical stimulation, with the net power being 111 µW. It was demonstrated that the proposed implantable power generation system has the potential to replace implantable batteries for active implantable medical devices.

  18. Implantable power generation system utilizing muscle contractions excited by electrical stimulation.

    PubMed

    Sahara, Genta; Hijikata, Wataru; Tomioka, Kota; Shinshi, Tadahiko

    2016-06-01

    An implantable power generation system driven by muscle contractions for supplying power to active implantable medical devices, such as pacemakers and neurostimulators, is proposed. In this system, a muscle is intentionally contracted by an electrical stimulation in accordance with the demands of the active implantable medical device for electrical power. The proposed system, which comprises a small electromagnetic induction generator, electrodes with an electrical circuit for stimulation and a transmission device to convert the linear motion of the muscle contractions into rotational motion for the magneto rotor, generates electrical energy. In an ex vivo demonstration using the gastrocnemius muscle of a toad, which was 28 mm in length and weighed 1.3 g, the electrical energy generated by the prototype exceeded the energy consumed for electrical stimulation, with the net power being 111 µW. It was demonstrated that the proposed implantable power generation system has the potential to replace implantable batteries for active implantable medical devices. PMID:27006422

  19. Spatio-temporal source modeling of evoked potentials to acoustic and cochlear implant stimulation.

    PubMed

    Ponton, C W; Don, M; Waring, M D; Eggermont, J J; Masuda, A

    1993-01-01

    Spatio-temporal source modeling (STSM) of event-related potentials was used to estimate the loci and characteristics of cortical activity evoked by acoustic stimulation in normal hearing subjects and by electrical stimulation in cochlear implant (CI) subjects. In both groups of subjects, source solutions obtained for the N1/P2 complex were located in the superior half of the temporal lobe in the head model. Results indicate that it may be possible to determine whether stimulation of different implant channels activates different regions of cochleotopically organized auditory cortex. Auditory system activation can be assessed further by examining the characteristics of the source wave forms. For example, subjects whose cochlear implants provided auditory sensations and normal hearing subjects had similar source activity. In contrast, a subject in whom implant activation evoked eyelid movements exhibited different source wave forms. STSM analysis may provide an electrophysiological technique for guiding rehabilitation programs based on the capabilities of the individual implant user and for disentangling the complex response patterns to electrical stimulation of the brain.

  20. Correction of Footdrop Due to Multiple Sclerosis Using the STIMuSTEP Implanted Dropped Foot Stimulator

    PubMed Central

    Wilkinson Hart, Ingrid A.; Khan, Mansoor S.; Slade-Sharman, Diana E.M.

    2016-01-01

    Background: Footdrop is a significant problem in multiple sclerosis, reducing the safety and efficiency of walking. Functional electrical stimulation (FES) can produce dorsiflexion, correcting footdrop. The purpose of this retrospective analysis of clinical study data was to compare the effect of external and implanted FES devices for the correction of footdrop. Methods: External FES was used for a minimum of 6 months before implantation. Walking performance was assessed using 10-m walking speed, 3-minute walking distance, the Physiological Cost Index, and health- and device-related quality of life and device-use questionnaires. Assessments were made before implantation and a mean (SD) of 128 (24) days after surgery, with additional walking speed measurements at 3 years. Results: Twenty-three people with multiple sclerosis received the STIMuSTEP implant. Both devices enabled statistically significant increases in walking speed and walking distance, with a strong trend toward a reduced Physiological Cost Index, indicating that walking required less effort (P = .07). Both devices improved device-related quality of life. Walking speed gain with FES was maintained at 3 years. Three implants failed after falls, and there was one case of neuropraxia. The implant was used more days per week and was quicker to put on each day than the external FES device. Conclusions: The STIMuSTEP implanted dropped foot stimulator is an effective long-term intervention for the correction of footdrop. PMID:27803639

  1. Concept Developed for an Implanted Stimulated Muscle-Powered Piezoelectric Generator

    NASA Technical Reports Server (NTRS)

    Lewandowski, Beth; Kilgore, Kevin; Ercegovic, David; Gustafson, Kenneth

    2005-01-01

    Implanted electronic devices are typically powered by batteries or transcutaneous power transmission. Batteries must be replaced or recharged, and transcutaneous power sources burden the patient or subject with external equipment prone to failure. A completely self-sustaining implanted power source would alleviate these limitations. Skeletal muscle provides an available autologous power source containing native chemical energy that produces power in excess of the requirements for muscle activation by motor nerve stimulation. A concept has been developed to convert stimulated skeletal muscle power into electrical energy (see the preceding illustration). We propose to connect a piezoelectric generator between a muscle tendon and bone. Electrically stimulated muscle contractions would exert force on the piezoelectric generator, charging a storage circuit that would be used to power the stimulator and other devices.

  2. Evoked EMG-based torque prediction under muscle fatigue in implanted neural stimulation

    NASA Astrophysics Data System (ADS)

    Hayashibe, Mitsuhiro; Zhang, Qin; Guiraud, David; Fattal, Charles

    2011-10-01

    In patients with complete spinal cord injury, fatigue occurs rapidly and there is no proprioceptive feedback regarding the current muscle condition. Therefore, it is essential to monitor the muscle state and assess the expected muscle response to improve the current FES system toward adaptive force/torque control in the presence of muscle fatigue. Our team implanted neural and epimysial electrodes in a complete paraplegic patient in 1999. We carried out a case study, in the specific case of implanted stimulation, in order to verify the corresponding torque prediction based on stimulus evoked EMG (eEMG) when muscle fatigue is occurring during electrical stimulation. Indeed, in implanted stimulation, the relationship between stimulation parameters and output torques is more stable than external stimulation in which the electrode location strongly affects the quality of the recruitment. Thus, the assumption that changes in the stimulation-torque relationship would be mainly due to muscle fatigue can be made reasonably. The eEMG was proved to be correlated to the generated torque during the continuous stimulation while the frequency of eEMG also decreased during fatigue. The median frequency showed a similar variation trend to the mean absolute value of eEMG. Torque prediction during fatigue-inducing tests was performed based on eEMG in model cross-validation where the model was identified using recruitment test data. The torque prediction, apart from the potentiation period, showed acceptable tracking performances that would enable us to perform adaptive closed-loop control through implanted neural stimulation in the future.

  3. Deafness alters auditory nerve fibre responses to cochlear implant stimulation.

    PubMed

    Sly, David J; Heffer, Leon F; White, Mark W; Shepherd, Robert K; Birch, Michael G J; Minter, Ricki L; Nelson, Niles E; Wise, Andrew K; O'Leary, Stephen J

    2007-07-01

    Here we characterized the relationship between duration of sensorineural hearing loss and the response of the auditory nerve to electrical stimulus rate. Electrophysiological recordings were made from undeafened guinea pigs and those ototoxically deafened for either 5 weeks or 6 months. Auditory neuron survival decreased significantly with the duration of deafness. Extracellular recordings were made from auditory nerve fibres responding to biphasic, charge-balanced current pulses delivered at rates of 20 and 200 pulses/s via a monopolar scala tympani stimulating electrode. The response to 20 pulses/s electrical stimulation of the deafened cochlea exhibited a decrease in spike latency, unaltered temporal jitter and unaltered dynamic range (of nerve firing rate against stimulus current), and a reduction in threshold after 6 months of deafness. The response to a 200-pulse/s stimulus was similar except that the dynamic range was greater than with 20 pulses/s and was also greater in deafened animals than in undeafened animals. Deafness and pulse rate are related; in deaf animals spike recovery appears to be complete between successive stimulus pulses at a low rate (20 pulses/s), but incomplete between pulses at a moderate pulse rate (200 pulses/s). These results suggest that changes in the function of individual auditory nerve fibres after deafness may affect clinical responses during high-rate stimulation such as that used in contemporary speech processing strategies, but not during lower rate stimulation such as that used to record evoked potentials. PMID:17650121

  4. 21 CFR 882.5830 - Implanted diaphragmatic/phrenic nerve stimulator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Implanted diaphragmatic/phrenic nerve stimulator. 882.5830 Section 882.5830 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... which an abnormally low amount of air enters the lungs) caused by brain stem disease, high...

  5. 21 CFR 882.5830 - Implanted diaphragmatic/phrenic nerve stimulator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Implanted diaphragmatic/phrenic nerve stimulator. 882.5830 Section 882.5830 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... which an abnormally low amount of air enters the lungs) caused by brain stem disease, high...

  6. 21 CFR 882.5830 - Implanted diaphragmatic/phrenic nerve stimulator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Implanted diaphragmatic/phrenic nerve stimulator. 882.5830 Section 882.5830 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... which an abnormally low amount of air enters the lungs) caused by brain stem disease, high...

  7. Effects of vestibular prosthesis electrode implantation and stimulation on hearing in rhesus monkeys.

    PubMed

    Dai, Chenkai; Fridman, Gene Y; Della Santina, Charles C

    2011-07-01

    To investigate the effects of vestibular prosthesis electrode implantation and activation on hearing in rhesus monkeys, we measured auditory brainstem responses (ABR) and distortion product otoacoustic emissions (DPOAE) in four rhesus monkeys before and after unilateral implantation of vestibular prosthesis electrodes in each of 3 left semicircular canals (SCC). Each of the 3 left SCCs were implanted with electrodes via a transmastoid approach. Right ears, which served as controls, were not surgically manipulated. Hearing tests were conducted before implantation (BI) and then 4 weeks post-implantation both without electrical stimulation (NS) and with electrical stimulation (S). During the latter condition, prosthetic electrical stimuli encoding 3 dimensions of head angular velocity were delivered to the 3 ampullary branches of the left vestibular nerve via each of 3 electrode pairs of a multichannel vestibular prosthesis. Electrical stimuli comprised charge-balanced biphasic pulses at a baseline rate of 94 pulses/s, with pulse frequency modulated from 48 to 222 pulses/s by head angular velocity. ABR hearing thresholds to clicks and tone pips at 1, 2, and 4 kHz increased by 5-10 dB from BI to NS and increased another ∼5 dB from NS to S in implanted ears. No significant change was seen in right ears. DPOAE amplitudes decreased by 2-14 dB from BI to NS in implanted ears. There was a slight but insignificant decrease of DPOAE amplitude and a corresponding increase of DPOAE/Noise floor ratio between NS and S in implanted ears. Vestibular prosthesis electrode implantation and activation have small but measurable effects on hearing in rhesus monkeys. Coupled with the clinical observation that patients with cochlear implants only rarely exhibit signs of vestibular injury or spurious vestibular nerve stimulation, these results suggest that although implantation and activation of multichannel vestibular prosthesis electrodes in human will carry a risk of hearing loss

  8. Overdentures on Implants for Better Quality of Life Among the Fully Edentulous Patients - Case Reports.

    PubMed

    Nikolovska, Julijana; Petrovski, Dragan; Petricevic, Nikola; Kapusevska, Biljana; Korunoska-Stevkovska, Vesna

    2015-01-01

    Global aging population has brought several challenges for their medical systems and total edentulism is one of them. The fabrication of removable acrylic dentures seems to be a simple and cheap treatment solution, but a majority of patients is not satisfied with their functional instability, causing limited diets, mouth soreness, speech and psycho-social problems etc. The results in many studies indicate an impact of oral conditions associated with the full denture wearing on oral-health related quality of life, especially in lower jaw. The reason for improper denture retention could be alveolar ridge bone resorption and numerous studies about this problem are plausible. Bone resorption in lower jaw may turn the alveolar ridge into a flabby soft tissue which is unable to sustain proper denture retention. The implant-retained prosthesis is an alternative treatment option in these situations. Implants will provide retention, stability, function and aesthetics and they are not so expensive solution. The aim of this article is to show solving of retention problems of a lower denture in two different clinical cases using implants and without any special technology. PMID:27442389

  9. Nanomaterials and synergistic low intensity direct current (LIDC) stimulation technology for orthopaedic implantable medical devices

    PubMed Central

    Samberg, Meghan E.; Cohen, Paul H.; Wysk, Richard A.; Monteiro-Riviere, Nancy A.

    2012-01-01

    Nanomaterials play a significant role in biomedical research and applications due to their unique biological, mechanical, and electrical properties. In recent years, they have been utilised to improve the functionality and reliability of a wide range of implantable medical devices ranging from well-established orthopaedic residual hardware devices (e.g. hip implants) that can repair defects in skeletal systems to emerging tissue engineering scaffolds that can repair or replace organ functions. This review summarizes the applications and efficacies of these nanomaterials that include synthetic or naturally occurring metals, polymers, ceramics, and composites in orthopaedic implants, the largest market segment of implantable medical devices. The importance of synergistic engineering techniques that can augment or enhance the performance of nanomaterial applications in orthopaedic implants is also discussed,, the focus being on a low intensity direct electric current (LIDC) stimulation technology to promote the long-term antibacterial efficacy of oligodynamic metal-based surfaces by ionization, while potentially accelerating tissue growth and osseointegration. While many nanomaterials have clearly demonstrated their ability to provide more effective implantable medical surfaces, further decisive investigations are necessary before they can translate into medically safe and commercially viable clinical applications. The paper concludes with a discussion about some of the critical impending issues with the application of nanomaterials-based technologies in implantable medical devices, and potential directions to address these. PMID:23335493

  10. Fabrication and In vivo Evaluation of Poly(3,4-ethylenedioxythiophene) Stimulus Electrodes for Fully Implantable Retinal Prosthesis

    NASA Astrophysics Data System (ADS)

    Kigure, Chikashi; Naganuma, Hideki; Sasaki, Yuichiro; Kino, Hisashi; Tomita, Hiroshi; Tanaka, Tetsu

    2013-04-01

    The development of poly(3,4-ethylenedioxythiophene) (PEDOT) stimulus electrodes and the relationship between the electrical stimulation of a rabbit retina and electrically evoked potential (EEP) were studied in detail. We fabricated implantable flexible cables with Pt, IrOx, and PEDOT electrodes and evaluated the electrochemical impedances (EIs) and charge injection capacities (CICs) of such electrodes. From the result, we confirmed that PEDOT electrodes have both lower EIs and larger CICs than Pt and IrOx electrodes. In addition, we performed in vivo experiments with PEDOT electrodes and clarified the relationships between the electrical stimulation of the rabbit retina and EEP. It is highly probable that visual restoration will be realized safely with PEDOT electrodes.

  11. In vivo demonstration of a self-sustaining, implantable, stimulated-muscle-powered piezoelectric generator prototype.

    PubMed

    Lewandowski, B E; Kilgore, K L; Gustafson, K J

    2009-11-01

    An implantable, stimulated-muscle-powered piezoelectric active energy harvesting generator was previously designed to exploit the fact that the mechanical output power of muscle is substantially greater than the electrical power necessary to stimulate the muscle's motor nerve. We reduced to practice the concept by building a prototype generator and stimulator. We demonstrated its feasibility in vivo, using rabbit quadriceps to drive the generator. The generated power was sufficient for self-sustaining operation of the stimulator and additional harnessed power was dissipated through a load resistor. The prototype generator was developed and the power generating capabilities were tested with a mechanical muscle analog. In vivo generated power matched the mechanical muscle analog, verifying its usefulness as a test-bed for generator development. Generator output power was dependent on the muscle stimulation parameters. Simulations and in vivo testing demonstrated that for a fixed number of stimuli/minute, two stimuli applied at a high frequency generated greater power than single stimuli or tetanic contractions. Larger muscles and circuitry improvements are expected to increase available power. An implanted, self-replenishing power source has the potential to augment implanted battery or transcutaneously powered electronic medical devices. PMID:19657742

  12. In Vivo Demonstration of a Self-Sustaining, Implantable, Stimulated-Muscle-Powered Piezoelectric Generator Prototype

    PubMed Central

    Lewandowski, B. E.; Kilgore, K. L.; Gustafson, K. J.

    2010-01-01

    An implantable, stimulated-muscle-powered piezoelectric active energy harvesting generator was previously designed to exploit the fact that the mechanical output power of muscle is substantially greater than the electrical power necessary to stimulate the muscle’s motor nerve. We reduced to practice the concept by building a prototype generator and stimulator. We demonstrated its feasibility in vivo, using rabbit quadriceps to drive the generator. The generated power was sufficient for self-sustaining operation of the stimulator and additional harnessed power was dissipated through a load resistor. The prototype generator was developed and the power generating capabilities were tested with a mechanical muscle analog. In vivo generated power matched the mechanical muscle analog, verifying its usefulness as a test-bed for generator development. Generator output power was dependent on the muscle stimulation parameters. Simulations and in vivo testing demonstrated that for a fixed number of stimuli/minute, two stimuli applied at a high frequency generated greater power than single stimuli or tetanic contractions. Larger muscles and circuitry improvements are expected to increase available power. An implanted, self-replenishing power source has the potential to augment implanted battery or transcutaneously powered electronic medical devices. PMID:19657742

  13. [The importance of nursing care in managing complications related to fully-implantable catheters].

    PubMed

    Bruzi, Luciana Mendes; Mendes, Danielle Cabral

    2011-04-01

    This is an experience report of a thirty-year-old female patient, diagnosed with recurrence of Acute Myeloid Leukemia, submitted to catheter implantation and presenting surgical wound necrosis. The following were used with success: collagenase, calcium alginate and oil lotion with essential fatty acids. It was found that the complications related to catheters are a great challenge in oncology nursing besides implying a delay in the oncological treatment. Making a correct decision as soon as possible is extremely important and avoids removing the catheter too soon.

  14. A fully integrated mixed-signal neural processor for implantable multichannel cortical recording.

    PubMed

    Sodagar, Amir M; Wise, Kensall D; Najafi, Khalil

    2007-06-01

    A 64-channel neural processor has been developed for use in an implantable neural recording microsystem. In the Scan Mode, the processor is capable of detecting neural spikes by programmable positive, negative, or window thresholding. Spikes are tagged with their associated channel addresses and formed into 18-bit data words that are sent serially to the external host. In the Monitor Mode, two channels can be selected and viewed at high resolution for studies where the entire signal is of interest. The processor runs from a 3-V supply and a 2-MHz clock, with a channel scan rate of 64 kS/s and an output bit rate of 2 Mbps.

  15. Investigation of Balance Function Using Dynamic Posturography under Electrical-Acoustic Stimulation in Cochlear Implant Recipients.

    PubMed

    Schwab, B; Durisin, M; Kontorinis, G

    2010-01-01

    Introduction. The purpose of the present study is to investigate the effect of electrical-acoustic stimulation on vestibular function in CI patients by using the EquiTest and to help answer the question of whether electrically stimulating the inner ear using a cochlear implant influences the balance system in any way. Material and Methods. A test population (n = 50) was selected at random from among the cochlear implant recipients. Dynamic posturography (using the EquiTest) was performed with the device switched off an switched on. Results. In summary, it can be said that an activated cochlear implant affects the function of the vestibular system and may, to an extent, even lead to a stabilization of balance function under the static conditions of dynamic posturography, but nevertheless also to a significant destabilization. Significant improvements in vestibular function were seen mainly in equilibrium scores under conditions 4 and 5, the composite equilibrium score, and the vestibular components as revealed by sensory analysis. Conclusions. Only under the static conditions are significantly poorer scores achieved when stimulation is applied. It may be that the explanation for any symptoms of dizziness lies precisely in the fact that they occur in supposedly noncritical situations, since, when the cochlear implant makes increased demands on the balance system, induced disturbances can be centrally suppressed. PMID:20671908

  16. Investigation of Balance Function Using Dynamic Posturography under Electrical-Acoustic Stimulation in Cochlear Implant Recipients

    PubMed Central

    Schwab, B.; Durisin, M.; Kontorinis, G.

    2010-01-01

    Introduction. The purpose of the present study is to investigate the effect of electrical-acoustic stimulation on vestibular function in CI patients by using the EquiTest and to help answer the question of whether electrically stimulating the inner ear using a cochlear implant influences the balance system in any way. Material and Methods. A test population (n = 50) was selected at random from among the cochlear implant recipients. Dynamic posturography (using the EquiTest) was performed with the device switched off an switched on. Results. In summary, it can be said that an activated cochlear implant affects the function of the vestibular system and may, to an extent, even lead to a stabilization of balance function under the static conditions of dynamic posturography, but nevertheless also to a significant destabilization. Significant improvements in vestibular function were seen mainly in equilibrium scores under conditions 4 and 5, the composite equilibrium score, and the vestibular components as revealed by sensory analysis. Conclusions. Only under the static conditions are significantly poorer scores achieved when stimulation is applied. It may be that the explanation for any symptoms of dizziness lies precisely in the fact that they occur in supposedly noncritical situations, since, when the cochlear implant makes increased demands on the balance system, induced disturbances can be centrally suppressed. PMID:20671908

  17. Feasibility of fully automated detection of fiducial markers implanted into the prostate using electronic portal imaging: A comparison of methods

    SciTech Connect

    Harris, Emma J. . E-mail: eharris@icr.ac.uk; McNair, Helen A.; Evans, Phillip M.

    2006-11-15

    Purpose: To investigate the feasibility of fully automated detection of fiducial markers implanted into the prostate using portal images acquired with an electronic portal imaging device. Methods and Materials: We have made a direct comparison of 4 different methods (2 template matching-based methods, a method incorporating attenuation and constellation analyses and a cross correlation method) that have been published in the literature for the automatic detection of fiducial markers. The cross-correlation technique requires a-priory information from the portal images, therefore the technique is not fully automated for the first treatment fraction. Images of 7 patients implanted with gold fiducial markers (8 mm in length and 1 mm in diameter) were acquired before treatment (set-up images) and during treatment (movie images) using 1MU and 15MU per image respectively. Images included: 75 anterior (AP) and 69 lateral (LAT) set-up images and 51 AP and 83 LAT movie images. Using the different methods described in the literature, marker positions were automatically identified. Results: The method based upon cross correlation techniques gave the highest percentage detection success rate of 99% (AP) and 83% (LAT) set-up (1MU) images. The methods gave detection success rates of less than 91% (AP) and 42% (LAT) set-up images. The amount of a-priory information used and how it affects the way the techniques are implemented, is discussed. Conclusions: Fully automated marker detection in set-up images for the first treatment fraction is unachievable using these methods and that using cross-correlation is the best technique for automatic detection on subsequent radiotherapy treatment fractions.

  18. Implantation of a defibrillator in a patient with an upper airway stimulation device.

    PubMed

    Ong, Adrian A; O'Brien, Terrence X; Nguyen, Shaun A; Gillespie, M Boyd

    2016-02-01

    The patient is a 62-year-old man with continuous positive airway pressure-intolerant obstructive sleep apnea who was enrolled in a study for a hypoglossal nerve upper airway stimulation device (UAS). Nearly 2.5 years later, he was admitted to the hospital for unstable angina. Diagnostic workup revealed a prior myocardial infarction, an ejection fraction of 30% on maximal medical therapy, and episodes of nonsustained ventricular tachycardia. During hospitalization, the patient received an implantable cardioverter defibrillator (ICD). This is the first reported case of simultaneous use of a UAS and an ICD, and we report no untoward device interference between the two implantable devices.

  19. A Single-Chip Full-Duplex High Speed Transceiver for Multi-Site Stimulating and Recording Neural Implants.

    PubMed

    Mirbozorgi, S Abdollah; Bahrami, Hadi; Sawan, Mohamad; Rusch, Leslie A; Gosselin, Benoit

    2016-06-01

    We present a novel, fully-integrated, low-power full-duplex transceiver (FDT) to support high-density and bidirectional neural interfacing applications (high-channel count stimulating and recording) with asymmetric data rates: higher rates are required for recording (uplink signals) than stimulation (downlink signals). The transmitter (TX) and receiver (RX) share a single antenna to reduce implant size and complexity. The TX uses impulse radio ultra-wide band (IR-UWB) based on an edge combining approach, and the RX uses a novel 2.4-GHz on-off keying (OOK) receiver. Proper isolation (>20 dB) between the TX and RX path is implemented 1) by shaping the transmitted pulses to fall within the unregulated UWB spectrum (3.1-7 GHz), and 2) by space-efficient filtering (avoiding a circulator or diplexer) of the downlink OOK spectrum in the RX low-noise amplifier. The UWB 3.1-7 GHz transmitter can use either OOK or binary phase shift keying (BPSK) modulation schemes. The proposed FDT provides dual band 500-Mbps TX uplink data rate and 100 Mbps RX downlink data rate, and it is fully integrated into standard TSMC 0.18- μm CMOS within a total size of 0.8 mm(2). The total measured power consumption is 10.4 mW in full duplex mode (5 mW at 100 Mbps for RX, and 5.4 mW at 500 Mbps or 10.8 pJ/bit for TX). Additionally, a 3-coil inductive link along with on-chip power management circuits allows to powering up the implantable transceiver wirelessly by delivering 25 mW extracted from a 13.56-MHz carrier signal, at a total efficiency of 41.6%. PMID:26469635

  20. Psychophysics, fitting, and signal processing for combined hearing aid and cochlear implant stimulation.

    PubMed

    Francart, Tom; McDermott, Hugh J

    2013-01-01

    The addition of acoustic stimulation to electric stimulation via a cochlear implant has been shown to be advantageous for speech perception in noise, sound quality, music perception, and sound source localization. However, the signal processing and fitting procedures of current cochlear implants and hearing aids were developed independently, precluding several potential advantages of bimodal stimulation, such as improved sound source localization and binaural unmasking of speech in noise. While there is a large and increasing population of implantees who use a hearing aid, there are currently no generally accepted fitting methods for this configuration. It is not practical to fit current commercial devices to achieve optimal binaural loudness balance or optimal binaural cue transmission for arbitrary signals and levels. There are several promising experimental signal processing systems specifically designed for bimodal stimulation. In this article, basic psychophysical studies with electric acoustic stimulation are reviewed, along with the current state of the art in fitting, and experimental signal processing techniques for electric acoustic stimulation. PMID:24165299

  1. Duplex communicable implanted antenna for magnetic direct feeding method: Functional electrical stimulation

    NASA Astrophysics Data System (ADS)

    Kato, Kentaro; Matsuki, Hidetoshi; Sato, Fumihiro; Satoh, Tadakuni; Handa, Nobuyasu

    2009-04-01

    Functional electrical stimulation (FES) is the therapy used for the rehabilitation of lost movement function by applying electrical stimulation (ES) to paralyzed extremities. To realize ES, we adapted the implanted direct feeding method (DFM). In this method, small implanted stimulators are placed under the skin at a depth of 10-20 mm and stimulus energy and signals for controlling devices are applied to them by a mounted system using magnetic coupling. This method has the merits of having no percutaneous points and high-precision stimulation. However, since the mounted system and implanted elements are separated, it is necessary to add feedback information from inside the body to confirm the system operation for safety therapy or to rehabilitate motor function smoothly. Satisfying both restrictions, we propose the magnetic connective dual resonance (MCDR) antenna, which has two resonance circuits. Adding the LC serial circuit to the LC parallel circuit gives the sending function. In this paper, we report the principle of the MCDR antenna and verify its duplex communication ability through communication experiment. This antenna enables DFM of FES to rehabilitate more complex movements.

  2. Continuous Thoracic Sympathetic Ganglion Block in Complex Regional Pain Syndrome Patients with Spinal Cord Stimulation Implantation

    PubMed Central

    Kim, EungDon; Roh, MiSun; Kim, SooHyang; Jo, DaeHyun

    2016-01-01

    The sympathetic block is widely used for treating neuropathic pain such as complex regional pain syndrome (CRPS). However, single sympathetic block often provides only short-term effect. Moreover, frequent procedures for sympathetic block may increase the risk of complications. The use of epidural route may be limited by concern of infection in case of previous implantation of the spinal cord stimulation (SCS). In contrast, a continuous sympathetic block can be administered without such concerns. The continuous thoracic sympathetic block (TSGB) has been used to treat the ischemic disease and other neuropathic conditions such as postherpetic neuralgia. We administered continuous thoracic sympathetic block using catheter in CRPS patients who underwent SCS implantations and achieved desirable outcomes. We believe a continuous sympathetic block is a considerable option before performing neurolysis or radiofrequency rhizotomy and even after SCS implantation. PMID:27445617

  3. Assessment of responses to cochlear implant stimulation at different levels of the auditory pathway

    PubMed Central

    Abbas, Paul J.; Brown, Carolyn J.

    2014-01-01

    This paper reviews characteristics of both the electrically evoked compound action potential (ECAP) and analogous measures of cortically evoked responses (CAEP) to electrical stimulation in cochlear implant users. Specific comparisons are made between the two levels of processing for measures of threshold, growth of responses with increasing stimulus level, changes in stimulation electrode and, finally, in temporal response properties. The results are interpreted in a context that ECAPs primarily reflect the characteristics of the electrode-neural interface for an individual ear. CAEPs clearly are dependent on those peripheral responses but also reflect differences in central processing among individual implant users. The potential applicability of combined measures in clinical situations is discussed. PMID:25445817

  4. Simulation of CIS speech signal processing strategy based on electrical stimulating model of cochlear implant

    NASA Astrophysics Data System (ADS)

    Qian, Zheng; Yu, Dan

    2006-11-01

    During the operating course of Cochlear implant, the speech signal processing strategy converts original speech signal into dim current signal. And then this signal will be transmitted into the embedded electrode to stimulate the remnant auditory nerve to restore the audition of patient. It could be shown that the speech processing strategy is the key part to realize the performance of cochlear implant, but its evaluation method for validity is always lacking. In this paper, the electrical stimulating model of cochlear implant is established at first, and then the acoustic simulation of Continuous Interleaved Sampling (CIS) strategy could be finished on this model. The synthesizing signal simulates the speech signal which could be heard by the deaf with cochlear implant. Therefore, the identification ability of CIS strategy could be estimated by delivering this synthesizing signal to normal audition people. Further more, some detailed analyses for every step of this acoustic simulation could be considered in order to improve the performance and parameters selection of CIS strategy. This work will be helpful for the deaf to enhance their perception and understanding during the speech identification course.

  5. Long-term stimulation by active epiretinal implants in normal and RCD1 dogs

    NASA Astrophysics Data System (ADS)

    Güven, Dilek; Weiland, James D.; Fujii, Gildo; Mech, Brian V.; Mahadevappa, Manjunatha; Greenberg, Robert; Roizenblatt, Roberto; Qiu, Guanting; La Bree, Laurie; Wang, Xiaopeng; Hinton, David; Humayun, Mark S.

    2005-03-01

    An epiretinal prosthesis, consisting of an extraocular microelectronic stimulator and an intraocular electrode array, was implanted in one eye of three blind and three sighted dogs. Three dogs (2 blind, 1 normal) were stimulated for 120 days, and two dogs (both normal) for 60 and 103 days respectively for 8-10 h/day at levels of 0.1 mC cm-2 and 0.05 mC cm-2, with each stimulus level presented to half of the array. One blind dog was kept as an inactive implant control. During the study period, electroretinograms (ERG) and fundus photographs were recorded. At the end of the study period, the dogs were sacrificed and histological and morphometric evaluation was made of the retina. No inflammatory reaction, neovascularization or hemorrhage was observed during the follow-up examinations. ERGs were unchanged. Stimulus levels used were of sufficient amplitude to elicit cortical evoked potentials. Histological evaluation showed no inflammatory infiltrates or changes in retina morphometry related to electrical stimulation when compared to the unstimulated control eye. Morphometric analysis revealed no consistent differences relating to electrical stimulation. In summary, chronic electrical stimulation of the dog retina at up to 0.1 mC cm-2 with an epiretinal prosthesis does not appear to adversely affect the retina. This study is supported by The Fletcher Jones Foundation, National Eye Institute Grants 1R24EY12893 and EY03040, the Whitaker Foundation and Second Sight Medical Products, Inc.

  6. Long-term stimulation by active epiretinal implants in normal and RCD1 dogs.

    PubMed

    Güven, Dilek; Weiland, James D; Fujii, Gildo; Mech, Brian V; Mahadevappa, Manjunatha; Greenberg, Robert; Roizenblatt, Roberto; Qiu, Guanting; Labree, Laurie; Wang, Xiaopeng; Hinton, David; Humayun, Mark S

    2005-03-01

    An epiretinal prosthesis, consisting of an extraocular microelectronic stimulator and an intraocular electrode array, was implanted in one eye of three blind and three sighted dogs. Three dogs (2 blind, 1 normal) were stimulated for 120 days, and two dogs (both normal) for 60 and 103 days respectively for 8-10 h/day at levels of 0.1 mC cm(-2) and 0.05 mC cm(-2), with each stimulus level presented to half of the array. One blind dog was kept as an inactive implant control. During the study period, electroretinograms (ERG) and fundus photographs were recorded. At the end of the study period, the dogs were sacrificed and histological and morphometric evaluation was made of the retina. No inflammatory reaction, neovascularization or hemorrhage was observed during the follow-up examinations. ERGs were unchanged. Stimulus levels used were of sufficient amplitude to elicit cortical evoked potentials. Histological evaluation showed no inflammatory infiltrates or changes in retina morphometry related to electrical stimulation when compared to the unstimulated control eye. Morphometric analysis revealed no consistent differences relating to electrical stimulation. In summary, chronic electrical stimulation of the dog retina at up to 0.1 mC cm(-2) with an epiretinal prosthesis does not appear to adversely affect the retina.

  7. Neural signal processing and closed-loop control algorithm design for an implanted neural recording and stimulation system.

    PubMed

    Hamilton, Lei; McConley, Marc; Angermueller, Kai; Goldberg, David; Corba, Massimiliano; Kim, Louis; Moran, James; Parks, Philip D; Sang Chin; Widge, Alik S; Dougherty, Darin D; Eskandar, Emad N

    2015-08-01

    A fully autonomous intracranial device is built to continually record neural activities in different parts of the brain, process these sampled signals, decode features that correlate to behaviors and neuropsychiatric states, and use these features to deliver brain stimulation in a closed-loop fashion. In this paper, we describe the sampling and stimulation aspects of such a device. We first describe the signal processing algorithms of two unsupervised spike sorting methods. Next, we describe the LFP time-frequency analysis and feature derivation from the two spike sorting methods. Spike sorting includes a novel approach to constructing a dictionary learning algorithm in a Compressed Sensing (CS) framework. We present a joint prediction scheme to determine the class of neural spikes in the dictionary learning framework; and, the second approach is a modified OSort algorithm which is implemented in a distributed system optimized for power efficiency. Furthermore, sorted spikes and time-frequency analysis of LFP signals can be used to generate derived features (including cross-frequency coupling, spike-field coupling). We then show how these derived features can be used in the design and development of novel decode and closed-loop control algorithms that are optimized to apply deep brain stimulation based on a patient's neuropsychiatric state. For the control algorithm, we define the state vector as representative of a patient's impulsivity, avoidance, inhibition, etc. Controller parameters are optimized to apply stimulation based on the state vector's current state as well as its historical values. The overall algorithm and software design for our implantable neural recording and stimulation system uses an innovative, adaptable, and reprogrammable architecture that enables advancement of the state-of-the-art in closed-loop neural control while also meeting the challenges of system power constraints and concurrent development with ongoing scientific research designed

  8. Neural signal processing and closed-loop control algorithm design for an implanted neural recording and stimulation system.

    PubMed

    Hamilton, Lei; McConley, Marc; Angermueller, Kai; Goldberg, David; Corba, Massimiliano; Kim, Louis; Moran, James; Parks, Philip D; Sang Chin; Widge, Alik S; Dougherty, Darin D; Eskandar, Emad N

    2015-08-01

    A fully autonomous intracranial device is built to continually record neural activities in different parts of the brain, process these sampled signals, decode features that correlate to behaviors and neuropsychiatric states, and use these features to deliver brain stimulation in a closed-loop fashion. In this paper, we describe the sampling and stimulation aspects of such a device. We first describe the signal processing algorithms of two unsupervised spike sorting methods. Next, we describe the LFP time-frequency analysis and feature derivation from the two spike sorting methods. Spike sorting includes a novel approach to constructing a dictionary learning algorithm in a Compressed Sensing (CS) framework. We present a joint prediction scheme to determine the class of neural spikes in the dictionary learning framework; and, the second approach is a modified OSort algorithm which is implemented in a distributed system optimized for power efficiency. Furthermore, sorted spikes and time-frequency analysis of LFP signals can be used to generate derived features (including cross-frequency coupling, spike-field coupling). We then show how these derived features can be used in the design and development of novel decode and closed-loop control algorithms that are optimized to apply deep brain stimulation based on a patient's neuropsychiatric state. For the control algorithm, we define the state vector as representative of a patient's impulsivity, avoidance, inhibition, etc. Controller parameters are optimized to apply stimulation based on the state vector's current state as well as its historical values. The overall algorithm and software design for our implantable neural recording and stimulation system uses an innovative, adaptable, and reprogrammable architecture that enables advancement of the state-of-the-art in closed-loop neural control while also meeting the challenges of system power constraints and concurrent development with ongoing scientific research designed

  9. Fiber-optic implantation for chronic optogenetic stimulation of brain tissue.

    PubMed

    Ung, Kevin; Arenkiel, Benjamin R

    2012-10-29

    Elucidating patterns of neuronal connectivity has been a challenge for both clinical and basic neuroscience. Electrophysiology has been the gold standard for analyzing patterns of synaptic connectivity, but paired electrophysiological recordings can be both cumbersome and experimentally limiting. The development of optogenetics has introduced an elegant method to stimulate neurons and circuits, both in vitro(1) and in vivo(2,3). By exploiting cell-type specific promoter activity to drive opsin expression in discrete neuronal populations, one can precisely stimulate genetically defined neuronal subtypes in distinct circuits(4-6). Well described methods to stimulate neurons, including electrical stimulation and/or pharmacological manipulations, are often cell-type indiscriminate, invasive, and can damage surrounding tissues. These limitations could alter normal synaptic function and/or circuit behavior. In addition, due to the nature of the manipulation, the current methods are often acute and terminal. Optogenetics affords the ability to stimulate neurons in a relatively innocuous manner, and in genetically targeted neurons. The majority of studies involving in vivo optogenetics currently use a optical fiber guided through an implanted cannula(6,7); however, limitations of this method include damaged brain tissue with repeated insertion of an optical fiber, and potential breakage of the fiber inside the cannula. Given the burgeoning field of optogenetics, a more reliable method of chronic stimulation is necessary to facilitate long-term studies with minimal collateral tissue damage. Here we provide our modified protocol as a video article to complement the method effectively and elegantly described in Sparta et al.(8) for the fabrication of a fiber optic implant and its permanent fixation onto the cranium of anesthetized mice, as well as the assembly of the fiber optic coupler connecting the implant to a light source. The implant, connected with optical fibers to a

  10. Hypoglossal Nerve Stimulator Implantation in an Adolescent With Down Syndrome and Sleep Apnea.

    PubMed

    Diercks, Gillian R; Keamy, Donald; Kinane, Thomas Bernard; Skotko, Brian; Schwartz, Allison; Grealish, Ellen; Dobrowski, John; Soose, Ryan; Hartnick, Christopher J

    2016-05-01

    Obstructive sleep apnea (OSA) is more common in children with Down syndrome, affecting up to 60% of patients, and may persist in up to 50% of patients after adenotonsillectomy. These children with persistent moderate to severe OSA require continuous positive airway pressure, which is often poorly tolerated, or even tracheotomy for severe cases. The hypoglossal nerve stimulator is an implantable device that produces an electrical impulse to the anterior branches of the hypoglossal nerve, resulting in tongue protrusion in response to respiratory variation. It is an effective treatment of sleep apnea in select adult patients because it allows for alleviation of tongue base collapse, improving airway obstruction. Herein we describe the first pediatric hypoglossal nerve stimulator implantation, which was performed in an adolescent with Down syndrome and refractory severe OSA (apnea hypopnea index [AHI]: 48.5 events/hour). The patient would not tolerate continuous positive airway pressure and required a long-standing tracheotomy. Hypoglossal nerve stimulator therapy was well tolerated and effective, resulting in significant improvement in the patient's OSA (overall AHI: 3.4 events/hour; AHI: 2.5-9.7 events/hour at optimal voltage settings depending on sleep stage and body position). Five months after implantation, the patient's tracheotomy was successfully removed and he continues to do well with nightly therapy. PMID:27244805

  11. Binaural release from masking with single- and multi-electrode stimulation in children with cochlear implants.

    PubMed

    Todd, Ann E; Goupell, Matthew J; Litovsky, Ruth Y

    2016-07-01

    Cochlear implants (CIs) provide children with access to speech information from a young age. Despite bilateral cochlear implantation becoming common, use of spatial cues in free field is smaller than in normal-hearing children. Clinically fit CIs are not synchronized across the ears; thus binaural experiments must utilize research processors that can control binaural cues with precision. Research to date has used single pairs of electrodes, which is insufficient for representing speech. Little is known about how children with bilateral CIs process binaural information with multi-electrode stimulation. Toward the goal of improving binaural unmasking of speech, this study evaluated binaural unmasking with multi- and single-electrode stimulation. Results showed that performance with multi-electrode stimulation was similar to the best performance with single-electrode stimulation. This was similar to the pattern of performance shown by normal-hearing adults when presented an acoustic CI simulation. Diotic and dichotic signal detection thresholds of the children with CIs were similar to those of normal-hearing children listening to a CI simulation. The magnitude of binaural unmasking was not related to whether the children with CIs had good interaural time difference sensitivity. Results support the potential for benefits from binaural hearing and speech unmasking in children with bilateral CIs. PMID:27475132

  12. Preclinical Evaluation of Poly(HEMA-co-acrylamide) Hydrogels Encapsulating Glucose Oxidase and Palladium Benzoporphyrin as Fully Implantable Glucose Sensors

    PubMed Central

    Unruh, Rachel M.; Roberts, Jason R.; Nichols, Scott P.; Gamsey, Soya; Wisniewski, Natalie A.; McShane, Michael J.

    2015-01-01

    Background: Continuous glucose monitors (CGMs) require percutaneous wire probes to monitor glucose. Sensors based on luminescent hydrogels are being explored as fully implantable alternatives to traditional CGMs. Our previous work investigated hydrogel matrices functionalized with enzymes and oxygen-quenched phosphors, demonstrating sensitivity to glucose, range of response, and biofouling strongly depend on the matrix material. Here, we further investigate the effect of matrix composition on overall performance in vitro and in vivo. Methods: Sensors based on three hydrogels, a poly(2-hydroxyethyl methacrylate) (pHEMA) homopolymer and 2 poly(2-hydroxyethyl methacrylate-co-acrylamide) (pHEMA-co-AAm) copolymers, were compared. These were used to entrap glucose oxidase (GOx), catalase, and an oxygen-sensitive benzoporphyrin phosphor. All sensor formulations were evaluated for glucose response and stability at physiological temperatures. Selected sensors were then evaluated as implanted sensors in a porcine model challenged with glucose and insulin. The animal protocol used in this study was approved by an IACUC committee at Texas A&M University. Results: PHEMA-co-AAm copolymer hydrogels (75:25 HEMA:AAm) yielded the most even GOx and dye dispersion throughout the hydrogel matrix and best preserved GOx apparent activity. In response to in vitro glucose challenges, this formulation exhibited a dynamic range of 12-167 mg/dL, a sensitivity of 1.44 ± 0.46 µs/(mg/dL), and tracked closely with reference capillary blood glucose values in vivo. Conclusions: The hydrogel-based sensors exhibited excellent sensitivity and sufficiently rapid response to the glucose levels achieved in vivo, proving feasibility of these materials for use in real-time glucose tracking. Extending the dynamic range and assessing long-term effects in vivo are ongoing efforts. PMID:26085565

  13. Enhanced tissue integration of implantable electrodes for sensing, and stimulation, via radio frequency glow discharge

    NASA Astrophysics Data System (ADS)

    O'Connor, Laurie M.

    Biopotential electrodes are conductive materials that convert electronic currents to or from ionic currents for sensing, and stimulating specific tissue sites for medical applications. Implanted electrodes become "walled off" by the foreign body tissue reactions producing poorly attached scar capsules dominated by surrounding dense collagenous lamellae and source fibroblasts which are electrically resistive. The conductive interstitial fluid that is typical between an electrode and the resistive capsule allows spurious current paths. The insulating layer increases the distance between the electrode and the target sites and poor attachment often results in electrode migration within the host tissue. This investigation tested the hypothesis that surface-energy modulation of electrodes, via Radio Frequency Glow Discharge Treatment (RFGDT), can improve the performance of tissue-implantable electrodes by reducing the foreign body tissue reaction and enhancing interfacial bonding between the tissue and electrode material. Previously published findings were reproduced in a pilot study of explanted reference grade medical-grade methyl silicone (PDMS) and commercially pure titanium (cpTi) materials and their tissue capsules from 30-day subcutaneous exposures in Balb/C mice. The low-critical surface tension PDMS produced thick, dense, poorly attached scar capsules while the higher-surface-energy commercially pure titanium (cpTi) produced more cellular and strongly attached tissue layers difficult to delaminate from the biomaterial. For the main body of work, cpTi, capacitor-grade Tantalum (Ta), and synthetic heart valve-quality Pyrolytic Carbon (PyC) were evaluated, representative of potential high-surface-energy implant electrode materials. Their surface characteristics were determined as-manufactured and after Radio Frequency Glow Discharge Treatment (RFGDT) by Critical Surface Tension (CST) measurement, Scanning Electron Microscopy (SEM), Energy Dispersive X

  14. Computational modeling of chemotactic signaling and aggregation of microglia around implantation site during deep brain stimulation

    NASA Astrophysics Data System (ADS)

    Silchenko, A. N.; Tass, P. A.

    2013-10-01

    It is well established that prolonged electrical stimulation of brain tissue causes massive release of ATP in the extracellular space. The released ATP and the products of its hydrolysis, such as ADP and adenosine, become the main elements mediating chemotactic sensitivity and motility of microglial cells via subsequent activation of P2Y2,12 as well as A3A and A2A adenosine receptors. The size of the sheath around the electrode formed by the microglial cells is an important criterion for the optimization of the parameters of electrical current delivered to brain tissue. Here, we study a purinergic signaling pathway underlying the chemotactic motion of microglia towards the implanted electrode during deep brain stimulation. We present a computational model describing formation of a stable aggregate around the implantation site due to the joint chemo-attractive action of ATP and ADP together with a mixed influence of extracellular adenosine. The model was built in accordance with the classical Keller-Segel approach and includes an equation for the cells' density as well as equations describing the hydrolysis of extracellular ATP via successive reaction steps ATP →ADP →AMP →adenosine. The results of our modeling allowed us to reveal the dependence of the width of the encapsulating layer around the electrode on the amount of ATP released due to permanent electrical stimulation. The dependences of the aggregates' size on the parameter governing the nonlinearity of interaction between extracellular adenosine and adenosine receptors are also analyzed.

  15. Wireless charing pillow for a fully implantable hearing aid: Design of a circular array coil based on finite element analysis for reducing magnetic weak zones.

    PubMed

    Lim, Hyung-Gyu; Kim, Jong Hoon; Shin, Dong Ho; Woo, Seong Tak; Seong, Ki Woong; Lee, Jyung Hyun; Kim, Myoung Nam; Wei, Qun; Cho, Jin-Ho

    2015-01-01

    Many types of fully implantable hearing aids have been developed. Most of these devices are implanted behind the ear. To maintain the implanted device for a long period of time, a rechargeable battery and wireless power transmission are used. Because inductive coupling is the most renowned method for wireless power transmission, many types of fully implantable hearing aids are transcutaneously powered using inductively coupled coils. Some patients with an implantable hearing aid require a method for conveniently charging their hearing aid while they are resting or sleeping. To address this need, a wireless charging pillow has been developed that employs a circular array coil as one of its primary parts. In this device, all primary coils are simultaneously driven to maintain an effective charging area regardless of head motion. In this case, however, there may be a magnetic weak zone that cannot be charged at the specific secondary coil's location on the array coil. In this study, assuming that a maximum charging distance is 4 cm, a circular array coil-serving as a primary part of the charging pillow-was designed using finite element analysis. Based on experimental results, the proposed device can charge an implantable hearing aid without a magnetic weak zone within 4 cm of the perpendicular distance between the primary and secondary coils. PMID:26405942

  16. Wireless charing pillow for a fully implantable hearing aid: Design of a circular array coil based on finite element analysis for reducing magnetic weak zones.

    PubMed

    Lim, Hyung-Gyu; Kim, Jong Hoon; Shin, Dong Ho; Woo, Seong Tak; Seong, Ki Woong; Lee, Jyung Hyun; Kim, Myoung Nam; Wei, Qun; Cho, Jin-Ho

    2015-01-01

    Many types of fully implantable hearing aids have been developed. Most of these devices are implanted behind the ear. To maintain the implanted device for a long period of time, a rechargeable battery and wireless power transmission are used. Because inductive coupling is the most renowned method for wireless power transmission, many types of fully implantable hearing aids are transcutaneously powered using inductively coupled coils. Some patients with an implantable hearing aid require a method for conveniently charging their hearing aid while they are resting or sleeping. To address this need, a wireless charging pillow has been developed that employs a circular array coil as one of its primary parts. In this device, all primary coils are simultaneously driven to maintain an effective charging area regardless of head motion. In this case, however, there may be a magnetic weak zone that cannot be charged at the specific secondary coil's location on the array coil. In this study, assuming that a maximum charging distance is 4 cm, a circular array coil-serving as a primary part of the charging pillow-was designed using finite element analysis. Based on experimental results, the proposed device can charge an implantable hearing aid without a magnetic weak zone within 4 cm of the perpendicular distance between the primary and secondary coils.

  17. An Integrated Implantable Stimulator That is Fail-Safe Without Off-Chip Blocking-Capacitors.

    PubMed

    Xiao Liu; Demosthenous, A; Donaldson, N

    2008-09-01

    We present a neural stimulator chip with an output stage (electrode driving circuit) that is fail-safe under single-fault conditions without the need for off-chip blocking-capacitors. To miniaturize the stimulator output stage two novel techniques are introduced. The first technique is a new current generator circuit reducing to a single step the translation of the digital input bits into the stimulus current, thus minimizing silicon area and power consumption compared to previous works. The current generator uses voltage-controlled resistors implemented by MOS transistors in the deep triode region. The second technique is a new stimulator output stage circuit with blocking-capacitor safety protection using a high-frequency current-switching (HFCS) technique. Unlike conventional stimulator output stage circuits for implantable functional electrical stimulation (FES) systems which require blocking-capacitors in the microfarad range, our proposed approach allows capacitance reduction to the picofarad range, thus the blocking-capacitors can be integrated on-chip. The prototype four-channel neural stimulator chip was fabricated in XFAB's 1-mum silicon-on-insulator CMOS technology and can operate from a power supply between 5-18 V. The stimulus current is generated by active charging and passive discharging. We obtained recordings of action potentials and a strength-duration curve from the sciatic nerve of a frog with the stimulator chip which demonstrate the HFCS technique. The average power consumption for a typical 1-mA 20-Hz single-channel stimulation using a book electrode, is 200 muW from a 6 V power supply. The silicon area occupation is 0.38 mm(2) per channel.

  18. An Integrated Implantable Stimulator That is Fail-Safe Without Off-Chip Blocking-Capacitors.

    PubMed

    Xiao Liu; Demosthenous, A; Donaldson, N

    2008-09-01

    We present a neural stimulator chip with an output stage (electrode driving circuit) that is fail-safe under single-fault conditions without the need for off-chip blocking-capacitors. To miniaturize the stimulator output stage two novel techniques are introduced. The first technique is a new current generator circuit reducing to a single step the translation of the digital input bits into the stimulus current, thus minimizing silicon area and power consumption compared to previous works. The current generator uses voltage-controlled resistors implemented by MOS transistors in the deep triode region. The second technique is a new stimulator output stage circuit with blocking-capacitor safety protection using a high-frequency current-switching (HFCS) technique. Unlike conventional stimulator output stage circuits for implantable functional electrical stimulation (FES) systems which require blocking-capacitors in the microfarad range, our proposed approach allows capacitance reduction to the picofarad range, thus the blocking-capacitors can be integrated on-chip. The prototype four-channel neural stimulator chip was fabricated in XFAB's 1-mum silicon-on-insulator CMOS technology and can operate from a power supply between 5-18 V. The stimulus current is generated by active charging and passive discharging. We obtained recordings of action potentials and a strength-duration curve from the sciatic nerve of a frog with the stimulator chip which demonstrate the HFCS technique. The average power consumption for a typical 1-mA 20-Hz single-channel stimulation using a book electrode, is 200 muW from a 6 V power supply. The silicon area occupation is 0.38 mm(2) per channel. PMID:23852972

  19. FREQUENCY-PLACE MAP FOR ELECTRICAL STIMULATION IN COCHLEAR IMPLANTS: CHANGE OVER TIME

    PubMed Central

    Vermeire, Katrien; Landsberger, David M.; Van de Heyning, Paul H.; Voormolen, Maurits; Punte, Andrea Kleine; Schatzer, Reinhold; Zierhofer, Clemens

    2015-01-01

    The relationship between the place of electrical stimulation from a cochlear implant and the corresponding perceived pitch remains uncertain. Previous studies have estimated what the pitch corresponding to a particular location should be. However, perceptual verification is difficult because a subject needs both a cochlear implant and sufficient residual hearing to reliably compare electric and acoustic pitches. Additional complications can arise from the possibility that the pitch corresponding to an electrode may change as the auditory system adapts to a sound processor. In the following experiment, five subjects with normal or near-to-normal hearing in one ear and a cochlear implant with a long electrode array in the other ear were studied. Pitch matches were made between single electrode pulse trains and acoustic tones before activation of the speech processor to gain an estimate of the pitch provided by electrical stimulation at a given insertion angle without the influence of exposure to a sound processor. The pitch matches were repeated after 1, 3, 6, and 12 months of experience with the sound processor to evaluate the effect of adaptation over time. Pre-activation pitch matches were lower than would be estimated by a spiral ganglion pitch map. Deviations were largest for stimulation below 240° degrees and smallest above 480°. With experience, pitch matches shifted towards the frequency-to-electrode allocation. However, no statistically significant pitch shifts were observed over time. The likely explanation for the lack of pitch change is that the frequency-to-electrode allocations for the long electrode arrays were already similar to the pre-activation pitch matches. Minimal place pitch shifts over time suggest a minimal amount of perceptual remapping needed for the integration of electric and acoustic stimuli, which may contribute to shorter times to asymptotic performance. PMID:25840373

  20. Frequency-place map for electrical stimulation in cochlear implants: Change over time.

    PubMed

    Vermeire, Katrien; Landsberger, David M; Van de Heyning, Paul H; Voormolen, Maurits; Kleine Punte, Andrea; Schatzer, Reinhold; Zierhofer, Clemens

    2015-08-01

    The relationship between the place of electrical stimulation from a cochlear implant and the corresponding perceived pitch remains uncertain. Previous studies have estimated what the pitch corresponding to a particular location should be. However, perceptual verification is difficult because a subject needs both a cochlear implant and sufficient residual hearing to reliably compare electric and acoustic pitches. Additional complications can arise from the possibility that the pitch corresponding to an electrode may change as the auditory system adapts to a sound processor. In the following experiment, five subjects with normal or near-to-normal hearing in one ear and a cochlear implant with a long electrode array in the other ear were studied. Pitch matches were made between single electrode pulse trains and acoustic tones before activation of the speech processor to gain an estimate of the pitch provided by electrical stimulation at a given insertion angle without the influence of exposure to a sound processor. The pitch matches were repeated after 1, 3, 6, and 12 months of experience with the sound processor to evaluate the effect of adaptation over time. Pre-activation pitch matches were lower than would be estimated by a spiral ganglion pitch map. Deviations were largest for stimulation below 240° degrees and smallest above 480°. With experience, pitch matches shifted towards the frequency-to-electrode allocation. However, no statistically significant pitch shifts were observed over time. The likely explanation for the lack of pitch change is that the frequency-to-electrode allocations for the long electrode arrays were already similar to the pre-activation pitch matches. Minimal place pitch shifts over time suggest a minimal amount of perceptual remapping needed for the integration of electric and acoustic stimuli, which may contribute to shorter times to asymptotic performance. PMID:25840373

  1. Divergent endometrial inflammatory cytokine expression at peri-implantation period and after the stimulation by copper intrauterine device

    PubMed Central

    Chou, Chia-Hung; Chen, Shee-Uan; Shun, Chia-Tung; Tsao, Po-Nien; Yang, Yu-Shih; Yang, Jehn-Hsiahn

    2015-01-01

    Endometrial inflammation has contradictory effects. The one occurring at peri-implantation period is favourable for embryo implantation, whereas the other occurring after the stimulation by copper intrauterine device (Cu-IUD) prevents from embryo implantation. In this study, 8 week female ICR mice were used to investigate the endometrial inflammation, in which they were at proestrus stage (Group 1), at peri-implantation period (Group 2), and had a copper wire implanted into right uterine horn (Group 3). Cytokine array revealed that two cytokines were highly expressed in Group 2 and Group 3 as compared with Group 1, and seven cytokines, including tumour necrosis factor α (TNF-α), had selectively strong expression in Group 3. Immunohistochemistry demonstrated prominent TNF-α staining on the endometrium after Cu-IUD stimulation, and in vitro culture of human endometrial glandular cells with Cu induced TNF-α secretion. The increased TNF-α concentration enhanced in vitro THP-1 cells chemotaxis, and reduced embryo implantation rates. These results suggest that inflammatory cytokine profiles of endometrium are different between those at peri-implantation period and after Cu-IUD stimulation, and TNF-α is the one with selectively strong expression in the latter. It might account for the contradictory biological effects of endometrial inflammation. PMID:26469146

  2. The parturient with implanted spinal cord stimulator: management and review of the literature.

    PubMed

    Young, Adam C; Lubenow, Timothy R; Buvanendran, Asokumar

    2015-01-01

    Spinal cord stimulation (SCS) is an approved treatment for complex regional pain syndrome and other chronic pain conditions. These devices enable women with chronic pain to maintain relatively normal lives, with some encountering pregnancy. Use of previously implanted SCS systems in pregnant women is considered controversial due to lack of long-term prospective studies evaluating both maternal and fetal safety. Seven patients at a university pain clinic were identified as having SCS implanted before becoming pregnant. Data on these patients before, during, and after labor were collected through chart review and patient interview. Onset of labor varied among the 7 patients (2 preterm and 5 term). Mode of anesthesia for delivery included 4 neuraxial anesthetics, with 3 successfully obtaining an adequate level of anesthesia for delivery. Four general anesthetics were administered for cesarean delivery, one of which included a failed attempt at neuraxial anesthesia. All infants were born healthy. Management approaches and outcomes in our patients, as well as those previously reported are discussed within this article. Definitive conclusions cannot be drawn from this small cohort. We believe that management of a parturient with an implanted SCS requires careful planning between all peripartum physicians. PMID:25899957

  3. Neurotherapeutic and neuroprosthetic effects of implanted functional electrical stimulation for ambulation after incomplete spinal cord injury.

    PubMed

    Bailey, Stephanie Nogan; Hardin, Elizabeth C; Kobetic, Rudi; Boggs, Lisa M; Pinault, Gilles; Triolo, Ronald J

    2010-01-01

    The purpose of this single-subject study was to determine the neurotherapeutic and neuroprosthetic effects of an implanted functional electrical stimulation (FES) system designed to facilitate walking in an individual with a longstanding motor and sensory incomplete spinal cord injury. An implanted pulse generator and eight intramuscular stimulating electrodes were installed unilaterally, activating weak or paralyzed hip flexors, hip and knee extensors, and ankle dorsiflexors during 36 sessions of gait training with FES. The neurotherapeutic effects were assessed by a comparison of pre- and posttraining volitional walking. The neuroprosthetic effects were assessed by a comparison of posttraining volitional and FES-assisted walking. Treatment resulted in significant (p < 0.005) volitional improvements in 6-minute walking distance and speed, speed during maximum walk, double support time, and 10 m walking speed. Posttraining FES-assisted walking resulted in significant additional improvements in all these measures, except 10 m walking speed. When the subject was using FES-assisted gait, maximum walking distance, peak knee flexion in swing, peak ankle dorsiflexion in swing, and knee extension moment also significantly increased. Neuroprosthetic gains were sufficient to enable the subject to advance from household ambulation to limited community ambulation. Additionally, the subject could perform multiple walks per day when using FES-assisted gait, which was impossible with volitional effort alone.

  4. The sensitivity and selectivity of an implantable two-channel peroneal nerve stimulator system for restoration of dropped foot.

    PubMed

    Kottink, Anke I R; Buschman, Hendrik P J; Kenney, Laurence P J; Veltink, Peter H; Slycke, Per; Bultstra, Gerrit; Hermens, Hermie J

    2004-10-01

    The objective of this study was to evaluate the stimulation responses on each channel of an implantable two-channel stimulator that stimulates the peroneal nerve branches innervating the muscles for dorsiflexion and eversion movements. Currently five Dutch patients and five English patients have been implanted with this system. Isometric ankle torque measurements were carried out in the patient with the longest follow-up period (1 y). A force sensor measured the three components of moment generated at the ankle joint. Stimulation intensity can be adjusted with great accuracy. Dorsiflexion moments are almost entirely determined by the setting of channel 1. Eversion moments are determined mainly by channel 2 and to a lesser extent by channel 1. Both channels determined abduction/adduction moments. We conclude that stimulation responses in both dorsiflexion and eversion direction can be set individually and with great accuracy and are reproducible over a prolonged period. PMID:22151337

  5. Bio-impedance characterization technique with implantable neural stimulator using biphasic current stimulus.

    PubMed

    Lo, Yi-Kai; Chang, Chih-Wei; Liu, Wentai

    2014-01-01

    Knowledge of the bio-impedance and its equivalent circuit model at the electrode-electrolyte/tissue interface is important in the application of functional electrical stimulation. Impedance can be used as a merit to evaluate the proximity between electrodes and targeted tissues. Understanding the equivalent circuit parameters of the electrode can further be leveraged to set a safe boundary for stimulus parameters in order not to exceed the water window of electrodes. In this paper, we present an impedance characterization technique and implement a proof-of-concept system using an implantable neural stimulator and an off-the-shelf microcontroller. The proposed technique yields the parameters of the equivalent circuit of an electrode through large signal analysis by injecting a single low-intensity biphasic current stimulus with deliberately inserted inter-pulse delay and by acquiring the transient electrode voltage at three well-specified timings. Using low-intensity stimulus allows the derivation of electrode double layer capacitance since capacitive charge-injection dominates when electrode overpotential is small. Insertion of the inter-pulse delay creates a controlled discharge time to estimate the Faradic resistance. The proposed method has been validated by measuring the impedance of a) an emulated Randles cells made of discrete circuit components and b) a custom-made platinum electrode array in-vitro, and comparing estimated parameters with the results derived from an impedance analyzer. The proposed technique can be integrated into implantable or commercial neural stimulator system at low extra power consumption, low extra-hardware cost, and light computation.

  6. Compact stacked planar inverted-F antenna for passive deep brain stimulation implants.

    PubMed

    Hosain, Md Kamal; Kouzani, Abbas Z; Tye, Susannah; Mortazavi, Daryoush; Kaynak, Akif

    2012-01-01

    A compact meandered three-layer stacked circular planar inverted-F antenna is designed and simulated at the UHF band (902.75 - 927.25 MHz) for passive deep brain stimulation implants. The UHF band is used because it offers small antenna size, and high data rate. The top and middle radiating layers are meandered, and low cost substrate and superstrate materials are used to limit the radius and height of the antenna to 5 mm and 1.64 mm, respectively. A dielectric substrate of FR-4 of ε(r)= 4.7 and δ= 0.018, and a biocompatible superstrate of silicone of er= 3.7 and d= 0.003 with thickness of 0.2 mm are used in the design. The resonance frequency of the proposed antenna is 918 MHz with a bandwidth of 24 MHz at return loss of -10 dB in free space. The antenna parameter such as 3D gain pattern of the designed antenna within a skin-tissue model is evaluated by using the finite element method. The compactness, wide bandwidth, round shape, and stable characteristics in skin make this antenna suitable for DBS. The feasibility of the wireless power transmission to the implant in the human head is also examined. PMID:23366026

  7. Development of a loudness normalisation strategy for combined cochlear implant and acoustic stimulation.

    PubMed

    Francart, Tom; McDermott, Hugh J

    2012-12-01

    Users of a cochlear implant together with a hearing aid in the non-implanted ear currently use devices that were developed separately and are often fitted separately. This results in very different growth of loudness with level in the two ears, potentially leading to decreased wearing comfort and suboptimal perception of interaural level differences. A loudness equalisation strategy, named 'SCORE bimodal', is proposed. It equalises loudness growth for the two modalities using existing models of loudness for acoustic and electric stimulation, and is suitable for implementation in wearable devices. Loudness balancing experiments were performed with six bimodal listeners to validate the strategy. In a first set of experiments, the function of each loudness model used was validated by balancing the loudness of four harmonic complexes of different bandwidths, ranging from 200 Hz to 1000 Hz, separately for each ear. Both the electric and acoustic loudness models predicted the data well. In a second set of experiments, binaural balancing was done for the same stimuli. It was found that SCORE significantly improved binaural balance.

  8. A zero-voltage switching technique for minimizing the current-source power of implanted stimulators.

    PubMed

    Çilingiroğlu, Uğur; İpek, Sercan

    2013-08-01

    The current-source power of an implanted stimulator is reduced almost to the theoretical minimum by driving the electrodes directly from the secondary port of the inductive link with a dedicated zero-voltage switching power supply. A feedback loop confined to the secondary of the inductive link adjusts the timing and conduction angle of switching to provide just the right amount of supply voltage needed for keeping the current-source voltage constant at or slightly above the compliance limit. Since drive is based on current rather than voltage, and supply-voltage update is near real-time, the quality of the current pulses is high regardless of how the electrode impedance evolves during stimulation. By scaling the switching frequency according to power demand, the technique further improves overall power consumption of the stimulator. The technique is implemented with a very simple control circuitry comprising a comparator, a Schmitt trigger and a logic gate of seven devices in addition to an on-chip switch and an off-chip capacitor. The power consumed by the proposed supply circuit itself is no larger than what the linear regulator of a conventional supply typically consumes for the same stimulation current. Still, the sum of supply and current-source power is typically between 20% and 75% of the conventional source power alone. Functionality of the proposed driver is verified experimentally on a proof-of-concept prototype built with 3.3 V devices in a 0.18 μm CMOS technology. PMID:23893206

  9. Cochlear Implant Electrode Effect on Sound Energy Transfer within the Cochlea during Acoustic Stimulation

    PubMed Central

    Greene, Nathaniel T.; Mattingly, Jameson K.; Jenkins, Herman A.; Tollin, Daniel J.; Easter, James R.; Cass, Stephen P.

    2015-01-01

    Hypothesis Cochlear implants (CI) designed for hearing preservation will not alter mechanical properties of the middle and inner ear as measured by intracochlear pressure (PIC) and stapes velocity (Vstap). Background CIs designed to provide combined electrical and acoustic stimulation (EAS) are now available. To maintain functional acoustic hearing, it is important to know if a CI electrode can alter middle or inner ear mechanics, as any alteration could contribute to elevated low-frequency thresholds in EAS patients. Methods Seven human cadaveric temporal bones were prepared, and pure-tone stimuli from 120Hz–10kHz were presented at a range of intensities up to 110 dB SPL. PIC in the scala vestibuli (PSV) and tympani (PST) were measured with fiber-optic pressure sensors concurrently with VStap using laser Doppler vibrometry. Five CI electrodes from two different manufacturers, with varying dimensions were inserted via a round window approach at six different depths (16–25 mm). Results The responses of PIC and VStap to acoustic stimulation were assessed as a function of stimulus frequency, normalized to SPL in the external auditory canal (EAC), in baseline and electrode inserted conditions. Responses measured with electrodes inserted were generally within ~5 dB of baseline, indicating little effect of cochlear implant electrode insertion on PIC and VStap. Overall, mean differences across conditions were small for all responses, and no substantial differences were consistently visible across electrode types. Conclusions Results suggest that the influence of a CI electrode on middle and inner ear mechanics is minimal, despite variation in electrode lengths and configurations. PMID:26333018

  10. Permanent implantation of peripheral nerve stimulator for combat injury-related ilioinguinal neuralgia.

    PubMed

    Banh, Diem Phuc T; Moujan, Pablo M; Haque, Quazi; Han, Tae-Hyung

    2013-01-01

    A peripheral nerve stimulator (PNS) can be an alternative for long-term pain relief refractory to conventional therapeutic modalities. We present a case of chronic incapacitating ilioinguinal neuralgia, which was successfully managed with permanent implantation of a peripheral nerve stimulator. A 26-year-old active duty African American man was referred to the University Pain Clinic with left ilioinguinal neuralgia due to shrapnel injury during his military service 6 years prior to his visit. Most of the shrapnel were surgically removed, but the patient subsequently developed left lower abdominal pain. Multiple surgeries, including inguinal herniorrhaphy, varicocelectomy, and orchiectomy, failed to provide satisfactory relief of his neuralgia. Other therapies tried resulting in limited outcomes were multiple ilioinguinal nerve blocks and cryoanalgesia. A trial of PNS was successful and the implantation of permanent leads was carried out. At his 3-month visit, the patient reported to have minimal pain, was tapered off oral analgesics, was able to return to work, and had resumed his normal daily activities. Recent technological advances in programming software and surgical techniques have led to renewed interest in PNS for the treatment of chronic refractory peripheral nerve injury. Despite our limited understanding of its exact mechanism of action, it can be considered as a therapeutic potential for a few carefully selected, intractable cases. Its minimally invasive and reversible features make PNS a favorable option for these patients. The stringent and rigorous screening procedures for suitable candidacy, documentation of previously failed treatments, psychiatric evaluation, and 3-5 days of preplacement trial, improve the success rate. PMID:24284860

  11. Effects of Maternal Sensitivity and Cognitive and Linguistic Stimulation on Cochlear Implant Users' Language Development over Four Years

    PubMed Central

    Quittner, Alexandra L.; Cruz, Ivette; Barker, David H.; Tobey, Emily; Eisenberg, Laurie S.; Niparko, John K.

    2013-01-01

    Objectives To examine the effects of observed maternal sensitivity (MS), cognitive stimulation (CS), and linguistic stimulation on the 4-year growth of oral language in young, deaf children receiving a cochlear implant. Previous studies of cochlear implants have not considered the effects of parental behaviors on language outcomes. Study design In this prospective, multisite study, we evaluated parent–child interactions during structured and unstructured play tasks and their effects on oral language development in 188 deaf children receiving a cochlear implant and 97 normal-hearing children as controls. Parent–child interactions were rated on a 7-point scale using the National Institute of Child Health and Human Development's Early Childcare Study codes, which have well-established psychometric properties. Language was assessed using the MacArthur Bates Communicative Development Inventories, the Reynell Developmental Language Scales, and the Comprehensive Assessment of Spoken Language. Results We used mixed longitudinal modeling to test our hypotheses. After accounting for early hearing experience and child and family demographics, MS and CS predicted significant increases in the growth of oral language. Linguistic stimulation was related to language growth only in the context of high MS. Conclusion The magnitude of effects of MS and CS on the growth of language was similar to that found for age at cochlear implantation, suggesting that addressing parenting behaviors is a critical target for early language learning after implantation. PMID:22985723

  12. Multi-microphone adaptive noise reduction strategies for coordinated stimulation in bilateral cochlear implant devices.

    PubMed

    Kokkinakis, Kostas; Loizou, Philipos C

    2010-05-01

    Bilateral cochlear implant (BI-CI) recipients achieve high word recognition scores in quiet listening conditions. Still, there is a substantial drop in speech recognition performance when there is reverberation and more than one interferers. BI-CI users utilize information from just two directional microphones placed on opposite sides of the head in a so-called independent stimulation mode. To enhance the ability of BI-CI users to communicate in noise, the use of two computationally inexpensive multi-microphone adaptive noise reduction strategies exploiting information simultaneously collected by the microphones associated with two behind-the-ear (BTE) processors (one per ear) is proposed. To this end, as many as four microphones are employed (two omni-directional and two directional) in each of the two BTE processors (one per ear). In the proposed two-microphone binaural strategies, all four microphones (two behind each ear) are being used in a coordinated stimulation mode. The hypothesis is that such strategies combine spatial information from all microphones to form a better representation of the target than that made available with only a single input. Speech intelligibility is assessed in BI-CI listeners using IEEE sentences corrupted by up to three steady speech-shaped noise sources. Results indicate that multi-microphone strategies improve speech understanding in single- and multi-noise source scenarios.

  13. Influence of implantation on the electrochemical properties of smooth and porous TiN coatings for stimulation electrodes

    NASA Astrophysics Data System (ADS)

    Meijs, S.; Sørensen, C.; Sørensen, S.; Rechendorff, K.; Fjorback, M.; Rijkhoff, N. J. M.

    2016-04-01

    Objective. To determine whether changes in electrochemical properties of porous titanium nitride (TiN) electrodes as a function of time after implantation are different from those of smooth TiN electrodes. Approach. Eight smooth and 8 porous TiN coated electrodes were implanted in 8 rats. Before implantation, voltage transients, cyclic voltammograms and impedance spectra were recorded in phosphate buffered saline (PBS). After implantation, these measurements were done weekly to investigate how smooth and porous electrodes were affected by implantation. Main results. The electrode capacitance of the porous TiN electrodes decreased more than the capacitance of the smooth electrodes due to acute implantation under fast measurement conditions (such as stimulation pulses). This indicates that protein adhesion presents a greater diffusion limitation for counter-ions for the porous than for the smooth electrodes. The changes in electrochemical properties during the implanted period were similar for smooth and porous TiN electrodes, indicating that cell adhesion poses a similar diffusion limitation for smooth and porous electrodes. Significance. This knowledge can be used to optimize the porous structure of the TiN film, so that the effect of protein adhesion on the electrochemical properties is diminished. Alternatively, an additional coating could be applied on the porous TiN that would prevent or minimize protein adhesion.

  14. Package architecture and component design for an implanted neural stimulator with closed loop control.

    PubMed

    Bjune, Caroline K; Marinis, Thomas F; Brady, Jeanne M; Moran, James; Wheeler, Jesse; Sriram, Tirunelveli S; Parks, Philip D; Widge, Alik S; Dougherty, Darin D; Eskandar, Emad N

    2015-08-01

    An implanted neural stimulator with closed loop control requires electrodes for stimulation pulses and recording neuron activity. Our system features arrays of 64 electrodes. Each electrode can be addressed through a cross bar switch, to enable it to be used for stimulation or recording. This electrode switch, a bank of low noise amplifiers with an integrated analog to digital converter, power conditioning electronics, and a communications and control gate array are co-located with the electrode array in a 14 millimeter diameter satellite package that is designed to be flush mounted in a skull burr hole. Our system features five satellite packages connected to a central hub processor-controller via ten conductor cables that terminate in a custom designed, miniaturized connector. The connector incorporates features of high reliability, military grade devices and utilizes three distinct seals to isolate the contacts from fluid permeation. The hub system is comprised of a connector header, hermetic electronics package, and rechargeable battery pack, which are mounted on and electrically interconnected by a flexible circuit board. The assembly is over molded with a compliant silicone rubber. The electronics package contains two antennas, a large coil, used for recharging the battery and a high bandwidth antenna that is used to download data and update software. The package is assembled from two machined alumina pieces, a flat base with brazed in, electrical feed through pins and a rectangular cover with rounded corners. Titanium seal rings are brazed onto these two pieces so that they can be sealed by laser welding. A third system antenna is incorporated in the flexible circuit board. It is used to communicate with an externally worn control package, which monitors the health of the system and allows both the user and clinician to control or modify various system function parameters. PMID:26738106

  15. Perceptual Spaces Induced by Cochlear Implant All-Polar Stimulation Mode.

    PubMed

    Marozeau, Jeremy; McKay, Colette M

    2016-01-01

    It has been argued that a main limitation of the cochlear implant is the spread of current induced by each electrode, which activates an inappropriately large range of sensory neurons. To reduce this spread, an alternative stimulation mode, the all-polar mode, was tested with five participants. It was designed to activate all the electrodes simultaneously with appropriate current levels and polarities to recruit narrower regions of auditory nerves at specific intracochlear electrode positions (denoted all-polar electrodes). In this study, the all-polar mode was compared with the current commercial stimulation mode: the monopolar mode. The participants were asked to judge the sound dissimilarity between pairs of two-electrode pulse-train stimuli that differed in the electrode positions and were presented in either monopolar or all-polar mode with pulses on the two electrodes presented either sequentially or simultaneously. The dissimilarity ratings were analyzed using a multidimensional scaling technique and three-dimensional stimulus perceptual spaces were produced. For all the conditions (mode and simultaneity), the first perceptual dimension was highly correlated with the position of the most apical activated electrode of the electrical stimulation and the second dimension with the position of the most basal electrode. In both sequential and simultaneous conditions, the monopolar and all-polar stimuli were significantly separated by a third dimension, which may indicate that all-polar stimuli have a perceptual quality that differs from monopolar stimuli. Overall, the results suggest that both modes might successfully represent spectral information in a sound processing strategy. PMID:27604784

  16. Perceptual Spaces Induced by Cochlear Implant All-Polar Stimulation Mode

    PubMed Central

    McKay, Colette M.

    2016-01-01

    It has been argued that a main limitation of the cochlear implant is the spread of current induced by each electrode, which activates an inappropriately large range of sensory neurons. To reduce this spread, an alternative stimulation mode, the all-polar mode, was tested with five participants. It was designed to activate all the electrodes simultaneously with appropriate current levels and polarities to recruit narrower regions of auditory nerves at specific intracochlear electrode positions (denoted all-polar electrodes). In this study, the all-polar mode was compared with the current commercial stimulation mode: the monopolar mode. The participants were asked to judge the sound dissimilarity between pairs of two-electrode pulse-train stimuli that differed in the electrode positions and were presented in either monopolar or all-polar mode with pulses on the two electrodes presented either sequentially or simultaneously. The dissimilarity ratings were analyzed using a multidimensional scaling technique and three-dimensional stimulus perceptual spaces were produced. For all the conditions (mode and simultaneity), the first perceptual dimension was highly correlated with the position of the most apical activated electrode of the electrical stimulation and the second dimension with the position of the most basal electrode. In both sequential and simultaneous conditions, the monopolar and all-polar stimuli were significantly separated by a third dimension, which may indicate that all-polar stimuli have a perceptual quality that differs from monopolar stimuli. Overall, the results suggest that both modes might successfully represent spectral information in a sound processing strategy. PMID:27604784

  17. Package architecture and component design for an implanted neural stimulator with closed loop control.

    PubMed

    Bjune, Caroline K; Marinis, Thomas F; Brady, Jeanne M; Moran, James; Wheeler, Jesse; Sriram, Tirunelveli S; Parks, Philip D; Widge, Alik S; Dougherty, Darin D; Eskandar, Emad N

    2015-08-01

    An implanted neural stimulator with closed loop control requires electrodes for stimulation pulses and recording neuron activity. Our system features arrays of 64 electrodes. Each electrode can be addressed through a cross bar switch, to enable it to be used for stimulation or recording. This electrode switch, a bank of low noise amplifiers with an integrated analog to digital converter, power conditioning electronics, and a communications and control gate array are co-located with the electrode array in a 14 millimeter diameter satellite package that is designed to be flush mounted in a skull burr hole. Our system features five satellite packages connected to a central hub processor-controller via ten conductor cables that terminate in a custom designed, miniaturized connector. The connector incorporates features of high reliability, military grade devices and utilizes three distinct seals to isolate the contacts from fluid permeation. The hub system is comprised of a connector header, hermetic electronics package, and rechargeable battery pack, which are mounted on and electrically interconnected by a flexible circuit board. The assembly is over molded with a compliant silicone rubber. The electronics package contains two antennas, a large coil, used for recharging the battery and a high bandwidth antenna that is used to download data and update software. The package is assembled from two machined alumina pieces, a flat base with brazed in, electrical feed through pins and a rectangular cover with rounded corners. Titanium seal rings are brazed onto these two pieces so that they can be sealed by laser welding. A third system antenna is incorporated in the flexible circuit board. It is used to communicate with an externally worn control package, which monitors the health of the system and allows both the user and clinician to control or modify various system function parameters.

  18. Role of bimodal stimulation for auditory-perceptual skills development in children with a unilateral cochlear implant.

    PubMed

    Marsella, P; Giannantonio, S; Scorpecci, A; Pianesi, F; Micardi, M; Resca, A

    2015-12-01

    This is a prospective randomised study that evaluated the differences arising from a bimodal stimulation compared to a monaural electrical stimulation in deaf children, particularly in terms of auditory-perceptual skills development. We enrolled 39 children aged 12 to 36 months, suffering from severe-to-profound bilateral sensorineural hearing loss with residual hearing on at least one side. All were unilaterally implanted: 21 wore only the cochlear implant (CI) (unilateral CI group), while the other 18 used the CI and a contralateral hearing aid at the same time (bimodal group). They were assessed with a test battery designed to appraise preverbal and verbal auditory-perceptual skills immediately before and 6 and 12 months after implantation. No statistically significant differences were observed between groups at time 0, while at 6 and 12 months children in the bimodal group had better scores in each test than peers in the unilateral CI group. Therefore, although unilateral deafness/hearing does not undermine hearing acuity in normal listening, the simultaneous use of a CI and a contralateral hearing aid (binaural hearing through a bimodal stimulation) provides an advantage in terms of acquisition of auditory-perceptual skills, allowing children to achieve the basic milestones of auditory perception faster and in greater number than children with only one CI. Thus, "keeping awake" the contralateral auditory pathway, albeit not crucial in determining auditory acuity, guarantees benefits compared with the use of the implant alone. These findings provide initial evidence to establish shared guidelines for better rehabilitation of patients undergoing unilateral cochlear implantation, and add more evidence regarding the correct indications for bilateral cochlear implantation.

  19. Gastric electrical stimulation treatment of type 2 diabetes: effects of implantation versus meal-mediated stimulation. A randomized blinded cross-over trial.

    PubMed

    Lebovitz, Harold E; Ludvik, Bernhard; Kozakowski, Jaroslaw; Tarnowski, Wieslaw; Zelewski, Mateusz; Yaniv, Irit; Schwartz, Tse'ela

    2015-07-14

    Gastric electrical stimulation with the implanted DIAMOND device has been shown to improve glycemic control and decrease weight and systolic blood pressure in patients with type 2 diabetes inadequately controlled with oral antidiabetic agents. The objective of this study was to determine if device implantation alone (placebo effect) contributes to the long-term metabolic benefits of DIAMOND(®) meal-mediated gastric electrical stimulation in patients with type 2 diabetes. The study was a 48 week randomized, blinded, cross-over trial in university centers comparing glycemic improvement of DIAMOND(®) implanted patients with type 2 diabetic with no activation of the electrical stimulation (placebo) versus meal-mediated activation of the electrical signal. The endpoint was improvement in glycemic control (HbA1c) from baseline to 24 and 48 weeks. In period 1 (0-24 weeks), equal improvement in HbA1c occurred independent of whether the meal-mediated electrical stimulation was turned on or left off (HbA1c -0.80% and -0.85% [-8.8 and -9.0 mmol/mol]). The device placebo improvement proved to be transient as it was lost in period 2 (25-48 weeks). With electrical stimulation turned off, HbA1c returned toward baseline values (8.06 compared to 8.32%; 64.2 to 67.4 mmol/mol, P = 0.465). In contrast, turning the electrical stimulation on in period 2 sustained the decrease in HbA1c from baseline (-0.93%, -10.1mmol/mol, P = 0.001) observed in period 1. The results indicate that implantation of the DIAMOND device causes a transient improvement in HbA1c which is not sustained beyond 24 weeks. Meal-mediated electrical stimulation accounts for the significant improvement in HbA1c beyond 24 weeks. PMID:26177957

  20. Gastric electrical stimulation treatment of type 2 diabetes: effects of implantation versus meal-mediated stimulation. A randomized blinded cross-over trial

    PubMed Central

    Lebovitz, Harold E; Ludvik, Bernhard; Kozakowski, Jaroslaw; Tarnowski, Wieslaw; Zelewski, Mateusz; Yaniv, Irit; Schwartz, Tse’ela

    2015-01-01

    Gastric electrical stimulation with the implanted DIAMOND device has been shown to improve glycemic control and decrease weight and systolic blood pressure in patients with type 2 diabetes inadequately controlled with oral antidiabetic agents. The objective of this study was to determine if device implantation alone (placebo effect) contributes to the long-term metabolic benefits of DIAMOND® meal-mediated gastric electrical stimulation in patients with type 2 diabetes. The study was a 48 week randomized, blinded, cross-over trial in university centers comparing glycemic improvement of DIAMOND® implanted patients with type 2 diabetic with no activation of the electrical stimulation (placebo) versus meal-mediated activation of the electrical signal. The endpoint was improvement in glycemic control (HbA1c) from baseline to 24 and 48 weeks. In period 1 (0–24 weeks), equal improvement in HbA1c occurred independent of whether the meal-mediated electrical stimulation was turned on or left off (HbA1c −0.80% and −0.85% [−8.8 and −9.0 mmol/mol]). The device placebo improvement proved to be transient as it was lost in period 2 (25–48 weeks). With electrical stimulation turned off, HbA1c returned toward baseline values (8.06 compared to 8.32%; 64.2 to 67.4 mmol/mol, P = 0.465). In contrast, turning the electrical stimulation on in period 2 sustained the decrease in HbA1c from baseline (−0.93%, −10.1mmol/mol, P = 0.001) observed in period 1. The results indicate that implantation of the DIAMOND device causes a transient improvement in HbA1c which is not sustained beyond 24 weeks. Meal-mediated electrical stimulation accounts for the significant improvement in HbA1c beyond 24 weeks. PMID:26177957

  1. Spread of excitation varies for different electrical pulse shapes and stimulation modes in cochlear implants.

    PubMed

    Undurraga, Jaime A; Carlyon, Robert P; Macherey, Olivier; Wouters, Jan; van Wieringen, Astrid

    2012-08-01

    In cochlear implants (CI) bipolar (BP) electrical stimulation has been suggested as a method to reduce the spread of current along the cochlea. However, behavioral measurements in BP mode have shown either similar or worse performance than in monopolar (MP) mode. This could be explained by a bimodal excitation pattern, with two main excitation peaks at the sites of the stimulating electrodes. We measured the spread of excitation (SOE) by means of the electrically evoked compound action potential (ECAP), obtained using the forward-masked paradigm. The aim was to measure the bimodality of the excitation and to determine whether it could be reduced by using asymmetric pulses. Three types of maskers shapes were used: symmetric (SYM), pseudomonophasic (PS), and symmetric with a long inter-phase gap (SYM-IPG) pulses. Maskers were presented in BP + 9 (wide), BP + 3 (narrow) and MP (only SYM) mode on fixed electrodes. The SOE obtained with the MP masker showed a main excitation peak close to the masker electrode. Wide SYM maskers produced bimodal excitation patterns showing two peaks close to the electrodes of the masker channel, whereas SYM-IPG maskers showed a single main peak near the electrode for which the masker's second phase (responsible for most of the masking) was anodic. Narrow SYM maskers showed complex and wider excitation patterns than asymmetric stimuli consistent with the overlap of the patterns produced by each channel's electrodes. The masking produced by narrow SYM-IPG and PS stimuli was more pronounced close to the masker electrode for which the effective phase was anodic. These results showed that the anodic polarity is the most effective one in BP mode and that the bimodal patterns produced by SYM maskers could be partially reduced by using asymmetric pulses.

  2. Do we need to establish guidelines for patients with neuromodulation implantable devices, including spinal cord stimulators undergoing nonspinal surgeries?

    PubMed Central

    Ghaly, Ramsis F.; Tverdohleb, Tatiana; Candido, Kenneth D.; Knezevic, Nebojsa Nick

    2016-01-01

    Background: Spinal cord stimulation is currently approved to treat chronic intractable pain of the trunk and limbs. However, such implantable electronic devices are vulnerable to external electrical currents and magnetic fields. Within the hospitals and modern operating rooms (ORs), there is an abundance of electrical devices and other types of equipment that could interfere with such devices. Despite the increasing number of patients with neuromodulation implantable devices, there are no written guidelines available or consensus of cautions for such patients undergoing unrelated surgery. Case Descriptions: A 60-year-old female with a permanent St. Jude's spinal cord stimulator (SCS) presented for open total abdominal hysterectomy. Both the anesthesia and gynecology staffs were aware of the device presence, but were unaware of any precautions regarding intraoperative management. The device was found to be nonmagnetic resonance imaging compatible, and bipolar cautery was used instead of monopolar cautery. A 59-year-old female with a 9-year-old permanent Medtronic SCS, presented for right total hip arthroplasty. The device was switched off prior to entering the OR, bipolar cautery was used, and grounding pads were placed away from her battery site. In each case, the manufacturer's representative was contacted preoperative. Both surgeries proceeded uneventfully. Conclusions: The Food and Drug Administration safety information manual warns about the use of diathermy, concomitant implanted stimulation devices, lithotripsy, external defibrillation, radiation therapy, ultrasonic scanning, and high-output ultrasound, all of which can lead to permanent implant damage if not turned off prior to undertaking procedures. Lack of uniform guidelines makes intraoperative management, as well as remote anesthesia care of patients with previously implanted SCSs unsafe. PMID:26958424

  3. Active books: the design of an implantable stimulator that minimizes cable count using integrated circuits very close to electrodes.

    PubMed

    Liu, Xiao; Demosthenous, Andreas; Vanhoestenberghe, Anne; Jiang, Dai; Donaldson, Nick

    2012-06-01

    This paper presents an integrated stimulator that can be embedded in implantable electrode books for interfacing with nerve roots at the cauda equina. The Active Book overcomes the limitation of conventional nerve root stimulators which can only support a small number of stimulating electrodes due to cable count restriction through the dura. Instead, a distributed stimulation system with many tripole electrodes can be configured using several Active Books which are addressed sequentially. The stimulator was fabricated in a 0.6-μm high-voltage CMOS process and occupies a silicon area of 4.2 × 6.5 mm(2). The circuit was designed to deliver up to 8 mA stimulus current to tripole electrodes from an 18 V power supply. Input pad count is limited to five (two power and three control lines) hence requiring a specific procedure for downloading stimulation commands to the chip and extracting information from it. Supported commands include adjusting the amplitude of stimulus current, varying the current ratio at the two anodes in each channel, and measuring relative humidity inside the chip package. In addition to stimulation mode, the chip supports quiescent mode, dissipating less than 100 nA current from the power supply. The performance of the stimulator chip was verified with bench tests including measurements using tripoles in saline. PMID:23853144

  4. Characterization of pulse amplitude and pulse rate modulation for a human vestibular implant during acute electrical stimulation

    NASA Astrophysics Data System (ADS)

    Nguyen, T. A. K.; DiGiovanna, J.; Cavuscens, S.; Ranieri, M.; Guinand, N.; van de Berg, R.; Carpaneto, J.; Kingma, H.; Guyot, J.-P.; Micera, S.; Perez Fornos, A.

    2016-08-01

    Objective. The vestibular system provides essential information about balance and spatial orientation via the brain to other sensory and motor systems. Bilateral vestibular loss significantly reduces quality of life, but vestibular implants (VIs) have demonstrated potential to restore lost function. However, optimal electrical stimulation strategies have not yet been identified in patients. In this study, we compared the two most common strategies, pulse amplitude modulation (PAM) and pulse rate modulation (PRM), in patients. Approach. Four subjects with a modified cochlear implant including electrodes targeting the peripheral vestibular nerve branches were tested. Charge-equivalent PAM and PRM were applied after adaptation to baseline stimulation. Vestibulo-ocular reflex eye movement responses were recorded to evaluate stimulation efficacy during acute clinical testing sessions. Main results. PAM evoked larger amplitude eye movement responses than PRM. Eye movement response axes for lateral canal stimulation were marginally better aligned with PRM than with PAM. A neural network model was developed for the tested stimulation strategies to provide insights on possible neural mechanisms. This model suggested that PAM would consistently cause a larger ensemble firing rate of neurons and thus larger responses than PRM. Significance. Due to the larger magnitude of eye movement responses, our findings strongly suggest PAM as the preferred strategy for initial VI modulation.

  5. Psychophysically based site selection coupled with dichotic stimulation improves speech recognition in noise with bilateral cochlear implants

    PubMed Central

    Zhou, Ning; Pfingst, Bryan E.

    2012-01-01

    The ability to perceive important features of electrical stimulation varies across stimulation sites within a multichannel implant. The aim of this study was to optimize speech processor MAPs for bilateral implant users by identifying and removing sites with poor psychophysical performance. The psychophysical assessment involved amplitude-modulation detection with and without a masker, and a channel interaction measure quantified as the elevation in modulation detection thresholds in the presence of the masker. Three experimental MAPs were created on an individual-subject basis using data from one of the three psychophysical measures. These experimental MAPs improved the mean psychophysical acuity across the electrode array and provided additional advantages such as increasing spatial separations between electrodes and/or preserving frequency resolution. All 8 subjects showed improved speech recognition in noise with one or more experimental MAPs over their everyday-use clinical MAP. For most subjects, phoneme and sentence recognition in noise were significantly improved by a dichotic experimental MAP that provided better mean psychophysical acuity, a balanced distribution of selected stimulation sites, and preserved frequency resolution. The site-selection strategies serve as useful tools for evaluating the importance of psychophysical acuities needed for good speech recognition in implant users. PMID:22894220

  6. First-in-Man Demonstration of Fully Implanted Myoelectric Sensors for Control of an Advanced Electromechanical Arm by Transradial Amputees

    PubMed Central

    Pasquina, Paul F.; Evangelista, Melissa; Carvalho, Antonio J.; Lockhart, Joseph; Griffin, Sarah; Nanos, George; McKay, Patricia; Hansen, Morten; Ipsen, Derek; Vandersea, James; Butkus, Josef; Miller, Matthew; Murphy, Ian; Hankin, David

    2014-01-01

    Background Advanced motorized prosthetic devices are currently controlled by EMG signals generated by residual muscles and recorded by surface electrodes on the skin. These surface recordings are often inconsistent and unreliable, leading to high prosthetic abandonment rates for individuals with upper limb amputation. Surface electrodes are limited because of poor skin contact, socket rotation, residual limb sweating, and their ability to only record signals from superficial muscles, whose function frequently does not relate to the intended prosthetic function. More sophisticated prosthetic devices require a stable and reliable interface between the user and robotic hand to improve upper limb prosthetic function. New Method Implantable Myoelectric Sensors (IMES®) are small electrodes intended to detect and wirelessly transmit EMG signals to an electromechanical prosthetic hand via an electromagnetic coil built into the prosthetic socket. This system is designed to simultaneously capture EMG signals from multiple residual limb muscles, allowing the natural control of multiple degrees of freedom simultaneously. Results We report the status of the first FDA-approved clinical trial of the IMES® System. This study is currently in progress, limiting reporting to only preliminary results. Comparison with Existing Methods Our first subject has reported the ability to accomplish a greater variety and complexity of tasks in his everyday life compared to what could be achieved with his previous myoelectric prosthesis. Conclusion The interim results of this study indicate the feasibility of utilizing IMES® technology to reliably sense and wirelessly transmit EMG signals from residual muscles to intuitively control a three degree-of-freedom prosthetic arm. PMID:25102286

  7. Effects of Pulse Shape and Polarity on Sensitivity to Cochlear Implant Stimulation: A Chronic Study in Guinea Pigs.

    PubMed

    Macherey, Olivier; Cazals, Yves

    2016-01-01

    Most cochlear implants (CIs) stimulate the auditory nerve with trains of symmetric biphasic pulses consisting of two phases of opposite polarity. Animal and human studies have shown that both polarities can elicit neural responses. In human CI listeners, studies have shown that at suprathreshold levels, the anodic phase is more effective than the cathodic phase. In contrast, animal studies usually show the opposite trend. Although the reason for this discrepancy remains unclear, computational modelling results have proposed that the degeneration of the peripheral processes of the neurons could lead to a higher efficiency of anodic stimulation. We tested this hypothesis in ten guinea pigs who were deafened with an injection of sysomycin and implanted with a single ball electrode inserted in the first turn of the cochlea. Animals were tested at regular intervals between 1 week after deafening and up to 1 year for some of them. Our hypothesis was that if the effect of polarity is determined by the presence or absence of peripheral processes, the difference in polarity efficiency should change over time because of a progressive neural degeneration. Stimuli consisted of charge-balanced symmetric and asymmetric pulses allowing us to observe the response to each polarity individually. For all stimuli, the inferior colliculus evoked potential was measured. Results show that the cathodic phase was more effective than the anodic phase and that this remained so even several months after deafening. This suggests that neural degeneration cannot entirely account for the higher efficiency of anodic stimulation observed in human CI listeners.

  8. Effects of Pulse Shape and Polarity on Sensitivity to Cochlear Implant Stimulation: A Chronic Study in Guinea Pigs.

    PubMed

    Macherey, Olivier; Cazals, Yves

    2016-01-01

    Most cochlear implants (CIs) stimulate the auditory nerve with trains of symmetric biphasic pulses consisting of two phases of opposite polarity. Animal and human studies have shown that both polarities can elicit neural responses. In human CI listeners, studies have shown that at suprathreshold levels, the anodic phase is more effective than the cathodic phase. In contrast, animal studies usually show the opposite trend. Although the reason for this discrepancy remains unclear, computational modelling results have proposed that the degeneration of the peripheral processes of the neurons could lead to a higher efficiency of anodic stimulation. We tested this hypothesis in ten guinea pigs who were deafened with an injection of sysomycin and implanted with a single ball electrode inserted in the first turn of the cochlea. Animals were tested at regular intervals between 1 week after deafening and up to 1 year for some of them. Our hypothesis was that if the effect of polarity is determined by the presence or absence of peripheral processes, the difference in polarity efficiency should change over time because of a progressive neural degeneration. Stimuli consisted of charge-balanced symmetric and asymmetric pulses allowing us to observe the response to each polarity individually. For all stimuli, the inferior colliculus evoked potential was measured. Results show that the cathodic phase was more effective than the anodic phase and that this remained so even several months after deafening. This suggests that neural degeneration cannot entirely account for the higher efficiency of anodic stimulation observed in human CI listeners. PMID:27080654

  9. Evaluation of focused multipolar stimulation for cochlear implants in long-term deafened cats

    NASA Astrophysics Data System (ADS)

    George, Shefin S.; Wise, Andrew K.; Fallon, James B.; Shepherd, Robert K.

    2015-06-01

    Objective. Focused multipolar (FMP) stimulation has been shown to produce restricted neural activation using intracochlear stimulation in animals with a normal population of spiral ganglion neurons (SGNs). However, in a clinical setting, the widespread loss of SGNs and peripheral fibres following deafness is expected to influence the effectiveness of FMP. Approach. We compared the efficacy of FMP stimulation to both monopolar (MP) and tripolar (TP) stimulation in long-term deafened cat cochleae (n = 8). Unlike our previous study, these cochleae contained <10% of the normal SGN population adjacent to the electrode array. We also evaluated the effect of electrode position on stimulation modes by using either modiolar facing or lateral wall facing half-band electrodes. The spread of neural activity across the inferior colliculus, a major nucleus within the central auditory pathway, was used as a measure of spatial selectivity. Main results. In cochleae with significant SGN degeneration, we observed that FMP and TP stimulation resulted in greater spatial selectivity than MP stimulation (p < 0.001). However, thresholds were significantly higher for FMP and TP stimulation compared to MP stimulation (p < 0.001). No difference between FMP and TP stimulation was found in any measures. The high threshold levels for FMP stimulation was significantly reduced without compromising spatial selectivity by varying the degree of current focusing (referred as ‘partial-FMP’ stimulation). Spatial selectivity of all stimulation modes was unaffected by the electrode position. Finally, spatial selectivity in long-term deafened cochleae was significantly less than that of cochleae with normal SGN population (George S S et al 2014 J. Neural Eng. 11 065003). Significance. The present results indicate that the greater spatial selectivity of FMP and TP stimulation over MP stimulation is maintained in cochleae with significant neural degeneration and is not adversely affected by electrode

  10. Cathodic voltage-controlled electrical stimulation of titanium implants as treatment for methicillin-resistant Staphylococcus aureus periprosthetic infections.

    PubMed

    Ehrensberger, Mark T; Tobias, Menachem E; Nodzo, Scott R; Hansen, Lisa A; Luke-Marshall, Nicole R; Cole, Ross F; Wild, Linda M; Campagnari, Anthony A

    2015-02-01

    Effective treatment options are often limited for implant-associated orthopedic infections. In this study we evaluated the antimicrobial effects of applying cathodic voltage-controlled electrical stimulation (CVCES) of -1.8 V (vs. Ag/AgCl) to commercially pure titanium (cpTi) substrates with preformed biofilm-like structures of methicillin-resistant Staphylococcus aureus (MRSA). The in vitro studies showed that as compared to the open circuit potential (OCP) conditions, CVCES of -1.8 V for 1 h significantly reduced the colony-forming units (CFU) of MRSA enumerated from the cpTi by 97% (1.89 × 106 vs 6.45 × 104 CFU/ml) and from the surrounding solution by 92% (6.63 × 105 vs. 5.15 × 104 CFU/ml). The in vivo studies, utilizing a rodent periprosthetic infection model, showed that as compared to the OCP conditions, CVCES at -1.8 V for 1 h significantly reduced MRSA CFUs in the bone tissue by 87% (1.15 × 105 vs. 1.48 × 104 CFU/ml) and reduced CFU on the cpTi implant by 98% (5.48 × 104 vs 1.16 × 103 CFU/ml). The stimulation was not associated with histological changes in the host tissue surrounding the implant. As compared to the OCP conditions, the -1.8 V stimulation significantly increased the interfacial capacitance (18.93 vs. 98.25 μF/cm(2)) and decreased polarization resistance (868,250 vs. 108 Ω-cm(2)) of the cpTi. The antimicrobial effects are thought to be associated with these voltage-dependent electrochemical surface properties of the cpTi.

  11. Successful Spinal Cord Stimulator Trial and Permanent Implant in Patient with Diabetic Peripheral Neuropathy on Chronic Dual Antiplatelet Therapy.

    PubMed

    Covert, Brian P; Nobles, Ryan H

    2015-01-01

    The safety of neuraxial anesthetic techniques in the setting of oral and parenteral anticoagulation is an area of growing interest and clinical inquiry as the multitude of anticoagulant medications rapidly increases. Additionally, the indications for spinal cord stimulation therapy are evolving as both technique and technology in the field continue to advance. The estimated incidence of spinal hematoma following epidural injection has been estimated to be 1 in 150,000-200,000. However, there is very little data on the risk of indwelling spinal cord simulation leads and chronic use of anticoagulant medications. We would like to report a recent case for consideration in which a spinal cord stimulator trial was successful and led to permanent spinal cord stimulator implantation in a patient with diabetic peripheral neuropathy taking life-long aspirin and clopidogrel therapy secondary to extensive coronary and carotid atherosclerosis. The report serves as a novel case to encourage exploration into the topic of anticoagulation therapy with indwelling spinal cord stimulator leads. The case brings up a number of critical questions that cannot clearly be answered with the current literature and some interesting topics for discussion including the need for acute systemic anticoagulation in the future for vascular interventions and risk stratification for those patients selected for spinal cord stimulation. PMID:26431144

  12. Stimulants

    MedlinePlus

    Stimulants are drugs that increase your heart rate, breathing rate, and brain function. Some stimulants affect only a specific organ, such as the heart, lungs, brain, or nervous system. Epinephrine is a stimulant. It ...

  13. The Prediction of Speech Recognition in Noise With a Semi-Implantable Bone Conduction Hearing System by External Bone Conduction Stimulation With Headband

    PubMed Central

    Ihler, Friedrich; Blum, Jenny; Berger, Max-Ulrich; Weiss, Bernhard G.; Welz, Christian

    2016-01-01

    Semi-implantable transcutaneous bone conduction devices are treatment options for conductive and mixed hearing loss (CHL/MHL). For counseling of patients, realistic simulation of the functional result is desirable. This study compared speech recognition in noise with a semi-implantable transcutaneous bone conduction device to external stimulation with a bone conduction device fixed by a headband. Eight German-language adult patients were enrolled after a semi-implantable transcutaneous bone conduction device (Bonebridge, Med-El) was implanted and fitted. Patients received a bone conduction device for external stimulation (Baha BP110, Cochlear) fixed by a headband for comparison. The main outcome measure was speech recognition in noise (Oldenburg Sentence Test). Pure-tone audiometry was performed and subjective benefit was assessed using the Glasgow Benefit Inventory and Abbreviated Profile of Hearing Aid Benefit questionnaires. Unaided, patients showed a mean signal-to-noise ratio threshold of 4.6 ± 4.2 dB S/N for speech recognition. The aided results were −3.3 ± 7.2 dB S/N by external bone conduction stimulation and −1.2 ± 4.0 dB S/N by the semi-implantable bone conduction device. The difference between the two devices was not statistically significant, while the difference was significant between unaided and aided situation for both devices. Both questionnaires for subjective benefit favored the semi-implantable device over external stimulation. We conclude that it is possible to simulate the result of speech recognition in noise with a semi-implantable transcutaneous bone conduction device by external stimulation. This should be part of preoperative counseling of patients with CHL/MHL before implantation of a bone conduction device. PMID:27698259

  14. Characteristics of stapedius muscle electromyograms elicited by cochlear implant stimulation in the rat.

    PubMed

    Clement, R S; Kipke, D R

    2004-01-01

    The electrical stapedius reflex (ESR) threshold, detected by eardrum acoustic impedance change, is strongly correlated with cochlear implant recipients' behavioral comfort levels. However reports suggest acoustic impedance changes are not detectable in 30-40% of patients. The goals of this study were to develop an animal model and investigate the characteristics of the stapedius muscle electromyogram (SEMG) elicited by a cochlear implant, as an alternative measure of ESR activation. Bipolar tungsten micro wire electrodes recorded the SEMG signal from the stapedius muscle of 6 rats. The cochlea was implanted with a multichannel intracochlear electrode that delivered biphasic electrical pulses. Maximum SEMG potentials were 20-500 microV (mean: 174 microV) or 8-42 dB SNR (mean: 24 dB). The dynamic range of the responses that reached saturation were approximately 10 dB, with threshold inversely dependent on pulse-width and electrode separation. The electrical brainstem response (EABR) threshold was 5.6 dB lower than the ESR threshold on average, but the standard deviation was relatively high (2.4 dB), suggesting that these two signals could provide independent information for objective cochlear implant fitting. Post-operative SEMGs were recorded in several animals; including one animal for up to 63 days. The results suggest the overall feasibility of the approach for objective cochlear implant fitting.

  15. Wireless data and power transfer of an optogenetic implantable visual cortex stimulator.

    PubMed

    Fattah, Nabeel; Laha, Soumyasanta; Sokolov, Danil; Chester, Graeme; Degenaar, Patrick

    2015-08-01

    In this paper, the wireless data and power transfer for a novel optogenetic visual cortex implant system was demonstrated by using pork tissue mimic in-vitro at the ISM 2.4 GHz and 13.5 MHz frequency band respectively. The observed data rate was 120 kbps with no loss in data for up to a thickness of 35 mm in both water & pork. To increase the power level of the implant a Class E power amplifier is separately designed and simulated for the transmitter end and has an output power of around 223 mW with an efficiency of 81.83%. The transferred power at the receiver was measured to be 66.80 mW for the pork tissue medium considering a distance of 5 mm between the transmitter and the receiver coils, with a coupling coefficient of ~0.8. This serves the power requirement of the visual cortex implant. PMID:26738150

  16. 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. PMID:27106306

  17. 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.

  18. ASIC or PIC? Implantable stimulators based on semi-custom CMOS technology or low-power microcontroller architecture.

    PubMed

    Salmons, S; Gunning, G T; Taylor, I; Grainger, S R; Hitchings, D J; Blackhurst, J; Jarvis, J C

    2001-01-01

    To gain a better understanding of the effects of chronic stimulation on mammalian muscles we needed to generate patterns of greater variety and complexity than simple constant-frequency or burst patterns. We describe here two approaches to the design of implantable neuromuscular stimulators that can satisfy these requirements. Devices of both types were developed and used in long-term experiments. The first device was based on a semi-custom Application Specific Integrated Circuit (ASIC). This approach has the advantage that the circuit can be completely tested at every stage of development and production, assuring a high degree of reliability. It has the drawback of inflexibility: the patterns are produced by state machines implemented in silicon, so each new set of patterns requires a fresh production run, which is costly and time-consuming. The second device was based on a commercial microcontroller (Microchip PIC16C84). The functionality of this type of circuit is specified in software rather than in silicon hardware, allowing a single device to be programmed for different functions. With the use of features designed to improve fault-tolerance we found this approach to be as reliable as that based on ASICs. The encapsulated devices can easily be accommodated subcutaneously on the flank of a rabbit and a recent version is small enough to implant into the peritoneal cavity of rats. The current devices are programmed with a predetermined set of 12 patterns before assembly; the desired pattern is selected after implantation with an electronic flash gun. The operating current drain is less than 40 microA.

  19. Cortical activation in profoundly deaf patients during cochlear implant stimulation demonstrated by H sub 2 (15)O PET

    SciTech Connect

    Herzog, H.; Lamprecht, A.; Kuehn, A.R.; Roden, W.; Vosteen, K.H.; Feinendegen, L.E. )

    1991-05-01

    Cochlear implants (CIs) are used to provide sensations of sound to profoundly deaf patients. The performance of the CI is assessed mainly by the subjective reports of patients. The aim of this study was to look for objective cortical responses to the stimulation of the CI. Two postlingually and two prelingually deaf patients were investigated by positron emission tomography (PET) using {sup 15}O-labeled water (H{sub 2}{sup 15}O) to determine the regional cerebral blood flow (rCBF). Instead of quantifying rCBF in absolute terms, it was estimated by referring the regional tissue concentration of H{sub 2}{sup 15}O to the mean whole brain concentration. CI stimulation encoded from white noise and sequential words led to an increased rCBF in the primary and secondary (Wernicke) auditory cortex. Relative elevations of up to 33% were observed bilaterally, although they were higher contralateral to the CI. These results were obtained not only in the postlingually deaf patients but also in two patients who had never been able to hear. Thus, it could be demonstrated that PET measurements of cerebral H{sub 2}{sup 15}O distribution yield objective responses of the central auditory system during electrical stimulation by CIs in profoundly deaf patients.

  20. A Programmable Implantable Microstimulator SoC With Wireless Telemetry: Application in Closed-Loop Endocardial Stimulation for Cardiac Pacemaker.

    PubMed

    Shuenn-Yuh Lee; Su, M Y; Ming-Chun Liang; You-Yin Chen; Cheng-Han Hsieh; Chung-Min Yang; Hsin-Yi Lai; Jou-Wei Lin; Qiang Fang

    2011-12-01

    A low-power, wireless, and implantable microstimulator system on chip with smart powering management, immediate neural signal acquisition, and wireless rechargeable system is proposed. A system controller with parity checking handles the adjustable stimulus parameters for the stimulated objective. In the current paper, the rat's intra-cardiac electrogram is employed as the stimulated model in the animal study, and it is sensed by a low-voltage and low-power monitoring analog front end. The power management unit, which includes a rectifier, battery charging and detection, and a regulator, is used for the power control of the internal circuits. The stimulation data and required clock are extracted by a phase-locked-loop-based phase shift keying demodulator from an inductive AC signal. The full chip, which consumes 48 μW only, is fabricated in a TSMC 0.35 μm 2P4M standard CMOS process to perform the monitoring and pacing functions with inductively powered communication in the in vivo study.

  1. The pros and cons of intraoperative CT scan in evaluation of deep brain stimulation lead implantation: A retrospective study

    PubMed Central

    Servello, Domenico; Zekaj, Edvin; Saleh, Christian; Pacchetti, Claudio; Porta, Mauro

    2016-01-01

    Background: Deep brain stimulation (DBS) is an established therapy for movement disorders, such as Parkinson's disease (PD), dystonia, and tremor. The efficacy of DBS depends on the correct lead positioning. The commonly adopted postoperative radiological evaluation is performed with computed tomography (CT) scan and/or magnetic resonance imaging (MRI). Methods: We conducted a retrospective study on 202 patients who underwent DBS from January 2009 to October 2013. DBS indications were PD, progressive supranuclear palsy, tremor, dystonia, Tourette syndrome, obsessive compulsive disorder, depression, and Huntington's disease. Preoperatively, all patients underwent brain MRI and brain CT scan with the stereotactic frame positioned. The lead location was confirmed intraoperatively with CT. The CT images were subsequently transferred to the Stealth Station Medtronic and merged with the preoperative planning. On the first or second day after, implantation we performed a brain MRI to confirm the correct position of the lead. Results: In 14 patients, leads were in suboptimal position after intraoperative CT scan positioning. The cases with alteration in the Z-axis were corrected immediately under fluoroscopic guidance. In all the 14 patients, an immediate repositioning was done. Conclusions: Based on our data, intraoperative CT scan is fast, safe, and a useful tool in the evaluation of the position of the implanted lead. It also reduces the patient's discomfort derived from the transfer of the patient from the operating room to the radiological department. However, intraoperative CT should not be considered as a substitute for postoperative MRI. PMID:27583182

  2. Stimulation from Cochlear Implant Electrodes Assists with Recovery from Asymmetric Perceptual Tilt: Evidence from the Subjective Visual Vertical Test.

    PubMed

    Gnanasegaram, Joshua J; Parkes, William J; Cushing, Sharon L; McKnight, Carmen L; Papsin, Blake C; Gordon, Karen A

    2016-01-01

    Vestibular end organ impairment is highly prevalent in children who have sensorineural hearing loss (SNHL) rehabilitated with cochlear implants (CIs). As a result, spatial perception is likely to be impacted in this population. Of particular interest is the perception of visual vertical because it reflects a perceptual tilt in the roll axis and is sensitive to an imbalance in otolith function. The objectives of the present study were thus to identify abnormalities in perception of the vertical plane in children with SNHL and determine whether such abnormalities could be resolved with stimulation from the CI. Participants included 53 children (15.2 ± 4.0 years of age) with SNHL and vestibular loss, confirmed with vestibular evoked myogenic potential (VEMP) testing. Testing protocol was validated in a sample of nine young adults with normal hearing (28.8 ± 7.7 years). Perception of visual vertical was assessed using the static Subjective Visual Vertical (SVV) test performed with and without stimulation in the participants with cochleovestibular loss. Trains of electrical pulses were delivered by an electrode in the left and/or right ear. Asymmetric spatial orientation deficits were found in nearly half of the participants with CIs (24/53 [45%]). The abnormal perception in this cohort was exacerbated by visual tilts in the direction of their deficit. Electric pulse trains delivered using the CI shifted this abnormal perception towards center (i.e., normal; p = 0.007). Importantly, this benefit was realized regardless of which ear was stimulated. These results suggest a role for CI stimulation beyond the auditory system, in particular, for improving vestibular/balance function. PMID:27679562

  3. Stimulation from Cochlear Implant Electrodes Assists with Recovery from Asymmetric Perceptual Tilt: Evidence from the Subjective Visual Vertical Test

    PubMed Central

    Gnanasegaram, Joshua J.; Parkes, William J.; Cushing, Sharon L.; McKnight, Carmen L.; Papsin, Blake C.; Gordon, Karen A.

    2016-01-01

    Vestibular end organ impairment is highly prevalent in children who have sensorineural hearing loss (SNHL) rehabilitated with cochlear implants (CIs). As a result, spatial perception is likely to be impacted in this population. Of particular interest is the perception of visual vertical because it reflects a perceptual tilt in the roll axis and is sensitive to an imbalance in otolith function. The objectives of the present study were thus to identify abnormalities in perception of the vertical plane in children with SNHL and determine whether such abnormalities could be resolved with stimulation from the CI. Participants included 53 children (15.2 ± 4.0 years of age) with SNHL and vestibular loss, confirmed with vestibular evoked myogenic potential (VEMP) testing. Testing protocol was validated in a sample of nine young adults with normal hearing (28.8 ± 7.7 years). Perception of visual vertical was assessed using the static Subjective Visual Vertical (SVV) test performed with and without stimulation in the participants with cochleovestibular loss. Trains of electrical pulses were delivered by an electrode in the left and/or right ear. Asymmetric spatial orientation deficits were found in nearly half of the participants with CIs (24/53 [45%]). The abnormal perception in this cohort was exacerbated by visual tilts in the direction of their deficit. Electric pulse trains delivered using the CI shifted this abnormal perception towards center (i.e., normal; p = 0.007). Importantly, this benefit was realized regardless of which ear was stimulated. These results suggest a role for CI stimulation beyond the auditory system, in particular, for improving vestibular/balance function. PMID:27679562

  4. Stimulation from Cochlear Implant Electrodes Assists with Recovery from Asymmetric Perceptual Tilt: Evidence from the Subjective Visual Vertical Test

    PubMed Central

    Gnanasegaram, Joshua J.; Parkes, William J.; Cushing, Sharon L.; McKnight, Carmen L.; Papsin, Blake C.; Gordon, Karen A.

    2016-01-01

    Vestibular end organ impairment is highly prevalent in children who have sensorineural hearing loss (SNHL) rehabilitated with cochlear implants (CIs). As a result, spatial perception is likely to be impacted in this population. Of particular interest is the perception of visual vertical because it reflects a perceptual tilt in the roll axis and is sensitive to an imbalance in otolith function. The objectives of the present study were thus to identify abnormalities in perception of the vertical plane in children with SNHL and determine whether such abnormalities could be resolved with stimulation from the CI. Participants included 53 children (15.2 ± 4.0 years of age) with SNHL and vestibular loss, confirmed with vestibular evoked myogenic potential (VEMP) testing. Testing protocol was validated in a sample of nine young adults with normal hearing (28.8 ± 7.7 years). Perception of visual vertical was assessed using the static Subjective Visual Vertical (SVV) test performed with and without stimulation in the participants with cochleovestibular loss. Trains of electrical pulses were delivered by an electrode in the left and/or right ear. Asymmetric spatial orientation deficits were found in nearly half of the participants with CIs (24/53 [45%]). The abnormal perception in this cohort was exacerbated by visual tilts in the direction of their deficit. Electric pulse trains delivered using the CI shifted this abnormal perception towards center (i.e., normal; p = 0.007). Importantly, this benefit was realized regardless of which ear was stimulated. These results suggest a role for CI stimulation beyond the auditory system, in particular, for improving vestibular/balance function.

  5. Practical considerations and nuances in anesthesia for patients undergoing deep brain stimulation implantation surgery

    PubMed Central

    Scharpf, Danielle Teresa; Sharma, Mayur; Rezai, Ali; Bergese, Sergio D.

    2015-01-01

    The field of functional neurosurgery has expanded in last decade to include newer indications, new devices, and new methods. This advancement has challenged anesthesia providers to adapt to these new requirements. This review aims to discuss the nuances and practical issues that are faced while administering anesthesia for deep brain stimulation surgery. PMID:26257844

  6. Development of implantable optoelectronic module for optical brain tissue stimulation in freely moving mice

    NASA Astrophysics Data System (ADS)

    Rusakov, Konstantin; Czajkowski, Rafał; Kaźmierczak, Andrzej

    2015-09-01

    The research aims to design and manufacture of wireless optogenetics devices for freely moving animals in cages IntelliCage system. The purpose of the device is to stimulate specific brain regions using light. The constructed device consists of a light source and optical fibre structure responsible for delivering light into the corresponding region of the brain of the animal. The size of the animal (mouse) and the fact that it is freely moving imposes substantial limitations with respect to the size and weight of the optoelectronic device. The present paper describes research on optical fibre structure fabrication, assembling it to the small size (less than 500 × 500 μm2 top surface) LED chip and experimental validation of the optoelectronic stimulator.

  7. Verbal cognition in deaf children using cochlear implants: effect of unilateral and bilateral stimulation.

    PubMed

    De Raeve, Leo; Vermeulen, Anneke; Snik, Ad

    2015-01-01

    The aim of this study is to assess the role of bilateral/bimodal device use in auditory speech perception in complex listening situations and long-term verbal cognition in deaf children using cochlear implants (CIs). Two groups of children are compared (unilateral and bilateral device users) concerning vocabulary, speech perception at conversational level and in complex listening situations, and verbal cognition. In this retrospective study, we collected data of 37 deaf children with normal learning potential of whom 16 were unilateral CI users and 21 were bilateral device users (9 with a bimodal fitting and 12 with bilateral CIs). We came to the conclusion that deaf children who use bilateral devices have the opportunity to develop good speech perception skills in complex listening conditions. These abilities enable at least some of the children to develop age-equivalent verbal cognition skills.

  8. Restoration of ankle movements with the ActiGait implantable drop foot stimulator: a safe and reliable treatment option for permanent central leg palsy.

    PubMed

    Martin, Klaus Daniel; Polanski, Witold Henryk; Schulz, Anne-Kathrin; Jöbges, Michael; Hoff, Hansjoerg; Schackert, Gabriele; Pinzer, Thomas; Sobottka, Stephan B

    2016-01-01

    OBJECT The ActiGait drop foot stimulator is a promising technique for restoration of lost ankle function by an implantable hybrid stimulation system. It allows ankle dorsiflexion by active peroneal nerve stimulation during the swing phase of gait. In this paper the authors report the outcome of the first prospective study on a large number of patients with stroke-related drop foot. METHODS Twenty-seven patients who experienced a stroke and with persisting spastic leg paresis received an implantable ActiGait drop foot stimulator for restoration of ankle movement after successful surface test stimulation. After 3 to 5 weeks, the stimulator was activated, and gait speed, gait endurance, and activation time of the system were evaluated and compared with preoperative gait tests. In addition, patient satisfaction was assessed using a questionnaire. RESULTS Postoperative gait speed significantly improved from 33.9 seconds per 20 meters to 17.9 seconds per 20 meters (p < 0.0001), gait endurance from 196 meters in 6 minutes to 401 meters in 6 minutes (p < 0.0001), and activation time from 20.5 seconds to 10.6 seconds on average (p < 0.0001). In 2 patients with nerve injury, surgical repositioning of the electrode cuff became necessary. One patient showed a delayed wound healing, and in another patient the system had to be removed because of a wound infection. Marked improvement in mobility, social participation, and quality of life was confirmed by 89% to 96% of patients. CONCLUSIONS The ActiGait implantable drop foot stimulator improves gait speed, endurance, and quality of life in patients with stroke-related drop foot. Regarding gait speed, the ActiGait system appears to be advantageous compared with foot orthosis or surface stimulation devices. Randomized trials with more patients and longer observation periods are needed to prove the long-term benefit of this device.

  9. Me, Myself and My Brain Implant: Deep Brain Stimulation Raises Questions of Personal Authenticity and Alienation.

    PubMed

    Kraemer, Felicitas

    2013-01-01

    In this article, I explore select case studies of Parkinson patients treated with deep brain stimulation (DBS) in light of the notions of alienation and authenticity. While the literature on DBS has so far neglected the issues of authenticity and alienation, I argue that interpreting these cases in terms of these concepts raises new issues for not only the philosophical discussion of neuro-ethics of DBS, but also for the psychological and medical approach to patients under DBS. In particular, I suggest that the experience of alienation and authenticity varies from patient to patient with DBS. For some, alienation can be brought about by neurointerventions because patients no longer feel like themselves. But, on the other hand, it seems alienation can also be cured by DBS as other patients experience their state of mind as authentic under treatment and retrospectively regard their former lives without stimulation as alienated. I argue that we must do further research on the relevance of authenticity and alienation to patients treated with DBS in order to gain a deeper philosophical understanding, and to develop the best evaluative criterion for the behavior of DBS patients.

  10. 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

  11. Elastic and viscoelastic mechanical properties of brain tissues on the implanting trajectory of sub-thalamic nucleus stimulation.

    PubMed

    Li, Yan; Deng, Jianxin; Zhou, Jun; Li, Xueen

    2016-11-01

    Corresponding to pre-puncture and post-puncture insertion, elastic and viscoelastic mechanical properties of brain tissues on the implanting trajectory of sub-thalamic nucleus stimulation are investigated, respectively. Elastic mechanical properties in pre-puncture are investigated through pre-puncture needle insertion experiments using whole porcine brains. A linear polynomial and a second order polynomial are fitted to the average insertion force in pre-puncture. The Young's modulus in pre-puncture is calculated from the slope of the two fittings. Viscoelastic mechanical properties of brain tissues in post-puncture insertion are investigated through indentation stress relaxation tests for six interested regions along a planned trajectory. A linear viscoelastic model with a Prony series approximation is fitted to the average load trace of each region using Boltzmann hereditary integral. Shear relaxation moduli of each region are calculated using the parameters of the Prony series approximation. The results show that, in pre-puncture insertion, needle force almost increases linearly with needle displacement. Both fitting lines can perfectly fit the average insertion force. The Young's moduli calculated from the slope of the two fittings are worthy of trust to model linearly or nonlinearly instantaneous elastic responses of brain tissues, respectively. In post-puncture insertion, both region and time significantly affect the viscoelastic behaviors. Six tested regions can be classified into three categories in stiffness. Shear relaxation moduli decay dramatically in short time scales but equilibrium is never truly achieved. The regional and temporal viscoelastic mechanical properties in post-puncture insertion are valuable for guiding probe insertion into each region on the implanting trajectory. PMID:27646405

  12. Elastic and viscoelastic mechanical properties of brain tissues on the implanting trajectory of sub-thalamic nucleus stimulation.

    PubMed

    Li, Yan; Deng, Jianxin; Zhou, Jun; Li, Xueen

    2016-11-01

    Corresponding to pre-puncture and post-puncture insertion, elastic and viscoelastic mechanical properties of brain tissues on the implanting trajectory of sub-thalamic nucleus stimulation are investigated, respectively. Elastic mechanical properties in pre-puncture are investigated through pre-puncture needle insertion experiments using whole porcine brains. A linear polynomial and a second order polynomial are fitted to the average insertion force in pre-puncture. The Young's modulus in pre-puncture is calculated from the slope of the two fittings. Viscoelastic mechanical properties of brain tissues in post-puncture insertion are investigated through indentation stress relaxation tests for six interested regions along a planned trajectory. A linear viscoelastic model with a Prony series approximation is fitted to the average load trace of each region using Boltzmann hereditary integral. Shear relaxation moduli of each region are calculated using the parameters of the Prony series approximation. The results show that, in pre-puncture insertion, needle force almost increases linearly with needle displacement. Both fitting lines can perfectly fit the average insertion force. The Young's moduli calculated from the slope of the two fittings are worthy of trust to model linearly or nonlinearly instantaneous elastic responses of brain tissues, respectively. In post-puncture insertion, both region and time significantly affect the viscoelastic behaviors. Six tested regions can be classified into three categories in stiffness. Shear relaxation moduli decay dramatically in short time scales but equilibrium is never truly achieved. The regional and temporal viscoelastic mechanical properties in post-puncture insertion are valuable for guiding probe insertion into each region on the implanting trajectory.

  13. Restoration of hearing by hearing aids: conventional hearing aids – implantable hearing aids – cochlear implants – auditory brainstem implants

    PubMed Central

    Leuwer, R.; Müller, J.

    2005-01-01

    Aim of this report is to explain the current concept of hearing restoration using hearing aids. At present the main issues of conventional hearing aids are the relative benefits of analogue versus digital devices and different strategies for the improvement of hearing in noise. Implantable hearing aids provide a better sound quality and less distortion. The lack of directional microphones is the major disadvantage of the partially implantable hearing aids commercially available. Two different clinical studies about fully implantable hearing aids have been started in 2004. One of the most-promising developments seems to be the electric-acoustic stimulation. PMID:22073051

  14. A microfabricated coil for implantable applications of magnetic spinal cord stimulation.

    PubMed

    Yu-Min Fu; Che-Yu Chen; Xin-Hong Qian; Yu-Ting Cheng; Chung-Yu Wu; Jui-Sheng Sun; Chien-Chun Huang; Chao-Kai Hu

    2015-08-01

    In this paper, a microfabricated inductive coil comprising of 125-turn coil windings and a MnZn-based magnetic core in a volume of 200 mm(3) is presented for the magnetic neural stimulation in a spinal cord. The coil winding with the parallel-linkage design instead of the typical serial-linkage one is proposed not only to provide better design flexibility to the current mode driving circuit but also to simplify the fabrication process of the 3-D inductive coil, which can further advance the coil miniaturization. Experimental results show the microcoil with a 1.5 A, 1 kHz square-wave current input can induce a voltages of ~220 μV on the conducting wire with an impedance of ~0.2 Ω @ 1 kHz, 1 mm separation. PMID:26737882

  15. Effect of mismatched place-of-stimulation on binaural fusion and lateralization in bilateral cochlear-implant usersa

    PubMed Central

    Kan, Alan; Stoelb, Corey; Litovsky, Ruth Y.; Goupell, Matthew J.

    2013-01-01

    Bilateral cochlear implants (CIs) have provided some success in improving spatial hearing abilities to patients, but with large variability in performance. One reason for the variability is that there may be a mismatch in the place-of-stimulation arising from electrode arrays being inserted at different depths in each cochlea. Goupell et al. [(2013b). J. Acoust. Soc. Am. 133(4), 2272–2287] showed that increasing interaural mismatch led to non-fused auditory images and poor lateralization of interaural time differences in normal hearing subjects listening to a vocoder. However, a greater bandwidth of activation helped mitigate these effects. In the present study, the same experiments were conducted in post-lingually deafened bilateral CI users with deliberate and controlled interaural mismatch of single electrode pairs. Results show that lateralization was still possible with up to 3 mm of interaural mismatch, even when off-center, or multiple, auditory images were perceived. However, mismatched inputs are not ideal since it leads to a distorted auditory spatial map. Comparison of CI and normal hearing listeners showed that the CI data were best modeled by a vocoder using Gaussian-pulsed tones with 1.5 mm bandwidth. These results suggest that interaural matching of electrodes is important for binaural cues to be maximally effective. PMID:24116428

  16. Biochemical acclimation, stomatal limitation and precipitation patterns underlie decreases in photosynthetic stimulation of soybean (Glycine max) at elevated [CO₂] and temperatures under fully open air field conditions.

    PubMed

    Rosenthal, David M; Ruiz-Vera, Ursula M; Siebers, Matthew H; Gray, Sharon B; Bernacchi, Carl J; Ort, Donald R

    2014-09-01

    The net effect of elevated [CO2] and temperature on photosynthetic acclimation and plant productivity is poorly resolved. We assessed the effects of canopy warming and fully open air [CO2] enrichment on (1) the acclimation of two biochemical parameters that frequently limit photosynthesis (A), the maximum carboxylation capacity of Rubisco (Vc,max) and the maximum potential linear electron flux through photosystem II (Jmax), (2) the associated responses of leaf structural and chemical properties related to A, as well as (3) the stomatal limitation (l) imposed on A, for soybean over two growing seasons in a conventionally managed agricultural field in Illinois, USA. Acclimation to elevated [CO2] was consistent over two growing seasons with respect to Vc,max and Jmax. However, elevated temperature significantly decreased Jmax contributing to lower photosynthetic stimulation by elevated CO2. Large seasonal differences in precipitation altered soil moisture availability modulating the complex effects of elevated temperature and CO2 on biochemical and structural properties related to A. Elevated temperature also reduced the benefit of elevated [CO2] by eliminating decreases in stomatal limitation at elevated [CO2]. These results highlight the critical importance of considering multiple environmental factors (i.e. temperature, moisture, [CO2]) when trying to predict plant productivity in the context of climate change.

  17. [Bone Conduction and Active Middle Ear Implants].

    PubMed

    Volkenstein, S; Thomas, J P; Dazert, S

    2016-05-01

    The majority of patients with moderate to severe hearing loss can be supplied with conventional hearing aids depending on severity and cause for hearing loss in a satisfying way. However, some patients either do not benefit enough from conventional hearing aids or cannot wear them due to inflammatory reactions and chronic infections of the external auditory canal or due to anatomical reasons. For these patients there are fully- and semi-implantable middle ear and bone conduction implants available. These devices either directly stimulate the skull (bone conduction devices), middle ear structures (active middle ear implants) or the cochlea itself (direct acoustic stimulation). Patients who failed surgical hearing rehabilitation or do not benefit from conventional hearing aids may achieve a significant better speech understanding and tremendous improvement in quality of life by implantable hearing devices with careful attention to the audiological and anatomical indication criteria.

  18. The Safety of Using Body-Transmit MRI in Patients with Implanted Deep Brain Stimulation Devices

    PubMed Central

    Kahan, Joshua; Papadaki, Anastasia; White, Mark; Mancini, Laura; Yousry, Tarek; Zrinzo, Ludvic; Limousin, Patricia; Hariz, Marwan; Foltynie, Tom; Thornton, John

    2015-01-01

    Background Deep brain stimulation (DBS) is an established treatment for patients with movement disorders. Patients receiving chronic DBS provide a unique opportunity to explore the underlying mechanisms of DBS using functional MRI. It has been shown that the main safety concern with MRI in these patients is heating at the electrode tips – which can be minimised with strict adherence to a supervised acquisition protocol using a head-transmit/receive coil at 1.5T. MRI using the body-transmit coil with a multi-channel receive head coil has a number of potential advantages including an improved signal-to-noise ratio. Study outline We compared the safety of cranial MRI in an in vitro model of bilateral DBS using both head-transmit and body-transmit coils. We performed fibre-optic thermometry at a Medtronic ActivaPC device and Medtronic 3389 electrodes during turbo-spin echo (TSE) MRI using both coil arrangements at 1.5T and 3T, in addition to gradient-echo echo-planar fMRI exposure at 1.5T. Finally, we investigated the effect of transmit-coil choice on DBS stimulus delivery during MRI. Results Temperature increases were consistently largest at the electrode tips. Changing from head- to body-transmit coil significantly increased the electrode temperature elevation during TSE scans with scanner-reported head SAR 0.2W/kg from 0.45°C to 0.79°C (p<0.001) at 1.5T, and from 1.25°C to 1.44°C (p<0.001) at 3T. The position of the phantom relative to the body coil significantly impacted on electrode heating at 1.5T; however, the greatest heating observed in any position tested remained <1°C at this field strength. Conclusions We conclude that (1) with our specific hardware and SAR-limited protocol, body-transmit cranial MRI at 1.5T does not produce heating exceeding international guidelines, even in cases of poorly positioned patients, (2) cranial MRI at 3T can readily produce heating exceeding international guidelines, (3) patients with ActivaPC Medtronic systems are safe

  19. Pain Control on Demand Based on Pulsed Radio-Frequency Stimulation of the Dorsal Root Ganglion Using a Batteryless Implantable CMOS SoC.

    PubMed

    Hung-Wei Chiu; Mu-Lien Lin; Chii-Wann Lin; I-Hsiu Ho; Wei-Tso Lin; Po-Hsiang Fang; Yi-Chin Lee; Yeong-Ray Wen; Shey-Shi Lu

    2010-12-01

    This paper presents the implementation of a batteryless CMOS SoC with low voltage pulsed radio-frequency (PRF) stimulation. This implantable SoC uses 402 MHz command signals following the medical implanted communication system (MICS) standard and a low frequency (1 MHz) for RF power transmission. A body floating type rectifier achieves 84% voltage conversion ratio. A bi-phasic pulse train of 1.4 V and 500 kHz is delivered by a PRF driver circuit. The PRF parameters include pulse duration, pulse frequency and repetition rate, which are controllable via 402 MHz RF receiver. The minimal required 3 V RF Vin and 2.2 V VDDr is achieved at 18 mm gap. The SoC chip is fabricated in a 0.35 μm CMOS process and mounted on a PCB with a flexible spiral antenna. The packaged PRF SoC was implanted into rats for the animal study. Von Frey was applied to test the mechanical allodynia in a blinded manner. This work has successfully demonstrated that implanted CMOS SoC stimulating DRG with 1.4 V, 500 kHz PRF could significantly reduce spinal nerve ligation (SNL) induced mechanical allodynia for 3-7 days. PMID:23850752

  20. Morphological Correlates of Hearing Loss after Cochlear Implantation and Electro-Acoustic Stimulation in a Hearing-Impaired Guinea Pig Model

    PubMed Central

    Reiss, Lina A.J.; Stark, Gemaine; Nguyen-Huynh, Anh T.; Spear, Kayce A.; Zhang, Hongzheng; Tanaka, Chiemi; Li, Hongzhe

    2016-01-01

    Hybrid or electro-acoustic stimulation (EAS) cochlear implants (CIs) are designed to provide high-frequency electric hearing together with residual low-frequency acoustic hearing. However, 30-50% of EAS CI recipients lose residual hearing after implantation. The objective of this study was to determine the mechanisms of EAS-induced hearing loss in an animal model with high-frequency hearing loss. Guinea pigs were exposed to 24 hours of noise (12-24 kHz at 116 dB) to induce a high-frequency hearing loss. After recovery, two groups of animals were implanted (n=6 per group), with one group receiving chronic acoustic and electric stimulation for 10 weeks, and the other group receiving no stimulation during this time frame. A third group (n=6) was not implanted, but received chronic acoustic stimulation. Auditory brainstem responses were recorded biweekly to monitor changes in hearing. The organ of Corti was immunolabeled with phalloidin, anti-CtBP2, and anti-GluR2 to quantify hair cells, ribbons and post-synaptic receptors. The lateral wall was immunolabeled with phalloidin and lectin to quantify stria vascularis capillary diameters. Bimodal or trimodal diameter distributions were observed; the number and location of peaks were objectively determined using the Aikake Information Criterion and Expectation Maximization algorithm. Noise exposure led to immediate hearing loss at 16-32 kHz for all groups. Cochlear implantation led to additional hearing loss at 4-8 kHz; this hearing loss was negatively and positively correlated with minimum and maximum peaks of the bimodal or trimodal distributions of stria vascularis capillary diameters, respectively. After chronic stimulation, no significant group changes in thresholds were seen; however, elevated thresholds at 1 kHz in implanted, stimulated animals were significantly correlated with decreased presynaptic ribbon and postsynaptic receptor counts. Inner and outer hair cell counts did not differ between groups and were not

  1. Morphological correlates of hearing loss after cochlear implantation and electro-acoustic stimulation in a hearing-impaired Guinea pig model.

    PubMed

    Reiss, Lina A J; Stark, Gemaine; Nguyen-Huynh, Anh T; Spear, Kayce A; Zhang, Hongzheng; Tanaka, Chiemi; Li, Hongzhe

    2015-09-01

    Hybrid or electro-acoustic stimulation (EAS) cochlear implants (CIs) are designed to provide high-frequency electric hearing together with residual low-frequency acoustic hearing. However, 30-50% of EAS CI recipients lose residual hearing after implantation. The objective of this study was to determine the mechanisms of EAS-induced hearing loss in an animal model with high-frequency hearing loss. Guinea pigs were exposed to 24 h of noise (12-24 kHz at 116 dB) to induce a high-frequency hearing loss. After recovery, two groups of animals were implanted (n = 6 per group), with one group receiving chronic acoustic and electric stimulation for 10 weeks, and the other group receiving no stimulation during this time frame. A third group (n = 6) was not implanted, but received chronic acoustic stimulation. Auditory brainstem responses were recorded biweekly to monitor changes in hearing. The organ of Corti was immunolabeled with phalloidin, anti-CtBP2, and anti-GluR2 to quantify hair cells, ribbons and post-synaptic receptors. The lateral wall was immunolabeled with phalloidin and lectin to quantify stria vascularis capillary diameters. Bimodal or trimodal diameter distributions were observed; the number and location of peaks were objectively determined using the Aikake Information Criterion and Expectation Maximization algorithm. Noise exposure led to immediate hearing loss at 16-32 kHz for all groups. Cochlear implantation led to additional hearing loss at 4-8 kHz; this hearing loss was negatively and positively correlated with minimum and maximum peaks of the bimodal or trimodal distributions of stria vascularis capillary diameters, respectively. After chronic stimulation, no significant group changes in thresholds were seen; however, elevated thresholds at 1 kHz in implanted, stimulated animals were significantly correlated with decreased presynaptic ribbon and postsynaptic receptor counts. Inner and outer hair cell counts did not differ between groups and

  2. Perception of Suprasegmental Speech Features via Bimodal Stimulation: Cochlear Implant on One Ear and Hearing Aid on the Other

    ERIC Educational Resources Information Center

    Most, Tova; Harel, Tamar; Shpak, Talma; Luntz, Michal

    2011-01-01

    Purpose: The purpose of the study was to evaluate the contribution of acoustic hearing to the perception of suprasegmental features by adults who use a cochlear implant (CI) and a hearing aid (HA) in opposite ears. Method: 23 adults participated in this study. Perception of suprasegmental features--intonation, syllable stress, and word…

  3. Are there a guidelines for implantable spinal cord stimulator therapy in patients using chronic anticoagulation therapy? - A review of decision-making in the high-risk patient

    PubMed Central

    Ghaly, Ramsis F.; Lissounov, Alexei; Candido, Kenneth D.; Knezevic, Nebojsa Nick

    2016-01-01

    Background: Spinal cord stimulators (SCSs) are gaining increasing indications and utility in an expanding variety of clinical conditions. Complications and initial expenses have historically prevented the early use of SCS therapy despite ongoing efforts to educate and promote its utilization. At present, there exists no literature evidence of SCS implantation in a chronically anticoagulated patient, and neuromodulation manufacturers are conspicuously silent in providing warnings or recommendations in the face of anticoagulant use chronically. It would appear as through these issues demand scrutiny and industry as well as neuromodulation society advocacy and support in terms of the provision of coherent guidelines on how to proceed. Case Description: A 79-year-old male returned to the neurosurgical clinic with persistent low back pain and leg heaviness due to adjacent level degenerative spondylosis and severe thoracic spinal stenosis. The patient had a notable history of multiple comorbidities along with atrial fibrillation requiring chronic anticoagulation. On initial presentation, he was educated with three choice of conservative medical therapy, intrathecal drug delivery system implantation, or additional lumbar decompression laminectomy with instrumented fusion of T10-L3 and a palliative surgical lead SCS implantation. Description: A 79-year-old male returned to the neurosurgical clinic with persistent low back pain and leg heaviness due to adjacent level degenerative spondylosis and severe thoracic spinal stenosis. The patient had a notable history of multiple comorbidities along with atrial fibrillation requiring chronic anticoagulation. On initial presentation, he was educated with three choice of conservative medical therapy, intrathecal drug delivery system implantation, or additional lumbar decompression laminectomy with instrumented fusion of T10-L3 and a palliative surgical lead SCS implantation. Conclusion: Our literature search did not reveal any

  4. Stimulation of titanium implant osseointegration through high-frequency vibration loading is enhanced when applied at high acceleration.

    PubMed

    Ogawa, Toru; Vandamme, Katleen; Zhang, Xiaolei; Naert, Ignace; Possemiers, Tine; Chaudhari, Amol; Sasaki, Keiichi; Duyck, Joke

    2014-11-01

    Low-magnitude high-frequency loading, applied by means of whole body vibration (WBV), affects the bone. Deconstructing a WBV loading stimulus into its constituent elements and investigating the effects of frequency and acceleration individually on bone tissue kinetics around titanium implants were aimed for in this study. A titanium implant was inserted in the tibia of 120 rats. The rats were divided into 1 control group (no loading) and 5 test groups with low (L), medium (M) or high (H) frequency ranges and accelerations [12-30 Hz at 0.3×g (F(L)A(H)); 70-90 Hz at 0.075×g (F(M)A(M)); 70-90 Hz at 0.3×g (F(M)A(H)); 130-150 Hz at 0.043×g (F(H)A(L)); 130-150 Hz at 0.3×g (F H A H)]. WBV was applied for 1 or 4 weeks. Implant osseointegration was evaluated by quantitative histology (bone-to-implant contact (BIC) and peri-implant bone formation (BV/TV)). A 2-way ANOVA (duration of experimental period; loading mode) with α = 0.05 was performed. BIC significantly increased over time and under load (p < 0.0001). The highest BICs were found for loading regimes at high acceleration with medium or high frequency (F(M)A(H) and F(H)A(H)), and significantly differing from F(L)A(H) and F(M)A(M) (p < 0.02 and p < 0.005 respectively). BV/TV significantly decreased over time (p < 0.0001). Loading led to a site-specific BV/TV increase (p < 0.001). The highest BV/TV responses were found for F(M)A(H) and F(H)A(H), significantly differing from F(M)A(M) (p < 0.005). The findings reveal the potential of high-frequency vibration loading to accelerate and enhance implant osseointegration, in particular when applied at high acceleration. Such mechanical signals hold great, though untapped, potential to be used as non-pharmacologic treatment for improving implant osseointegration in compromised bone.

  5. Stimulation of titanium implant osseointegration through high-frequency vibration loading is enhanced when applied at high acceleration.

    PubMed

    Ogawa, Toru; Vandamme, Katleen; Zhang, Xiaolei; Naert, Ignace; Possemiers, Tine; Chaudhari, Amol; Sasaki, Keiichi; Duyck, Joke

    2014-11-01

    Low-magnitude high-frequency loading, applied by means of whole body vibration (WBV), affects the bone. Deconstructing a WBV loading stimulus into its constituent elements and investigating the effects of frequency and acceleration individually on bone tissue kinetics around titanium implants were aimed for in this study. A titanium implant was inserted in the tibia of 120 rats. The rats were divided into 1 control group (no loading) and 5 test groups with low (L), medium (M) or high (H) frequency ranges and accelerations [12-30 Hz at 0.3×g (F(L)A(H)); 70-90 Hz at 0.075×g (F(M)A(M)); 70-90 Hz at 0.3×g (F(M)A(H)); 130-150 Hz at 0.043×g (F(H)A(L)); 130-150 Hz at 0.3×g (F H A H)]. WBV was applied for 1 or 4 weeks. Implant osseointegration was evaluated by quantitative histology (bone-to-implant contact (BIC) and peri-implant bone formation (BV/TV)). A 2-way ANOVA (duration of experimental period; loading mode) with α = 0.05 was performed. BIC significantly increased over time and under load (p < 0.0001). The highest BICs were found for loading regimes at high acceleration with medium or high frequency (F(M)A(H) and F(H)A(H)), and significantly differing from F(L)A(H) and F(M)A(M) (p < 0.02 and p < 0.005 respectively). BV/TV significantly decreased over time (p < 0.0001). Loading led to a site-specific BV/TV increase (p < 0.001). The highest BV/TV responses were found for F(M)A(H) and F(H)A(H), significantly differing from F(M)A(M) (p < 0.005). The findings reveal the potential of high-frequency vibration loading to accelerate and enhance implant osseointegration, in particular when applied at high acceleration. Such mechanical signals hold great, though untapped, potential to be used as non-pharmacologic treatment for improving implant osseointegration in compromised bone. PMID:25209971

  6. Biochemical acclimation, stomatal limitation and precipitation patterns underlie decreases in photosynthetic stimulation of Soybean (Glycine max) at elevated [CO2] and temperatures under fully open air field conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The net effect of elevated [CO2] and temperature on photosynthetic acclimation and plant productivity is poorly resolved. We assessed the effects of canopy warming and fully open air [CO2] enrichment on 1) the acclimation of two biochemical parameters that frequently limit photosynthesis (A), the ma...

  7. Continuous light after a long-day treatment is equivalent to melatonin implants to stimulate testosterone secretion in Alpine male goats.

    PubMed

    Delgadillo, J A; Vélez, L I; Flores, J A

    2016-04-01

    In rams, artificial long days followed by continuous light stimulate testosterone secretion during the non-breeding season. The objective of this study was to determine whether artificial long days followed by continuous light could stimulate testosterone secretion in Alpine bucks as well as in those exposed to long days followed by a melatonin treatment. All bucks were kept in shaded open pens. Control males were exposed to natural photoperiod conditions (n=5). Males of the two experimental groups were exposed to 2.5 months of long days from 1 December (n=5 each). On 16 February, one group of males was exposed to 24 h of light per day until 30 June; the other group was exposed to natural variations of photoperiod and received two s.c. melatonin implants. Testicular weight was determined every 2 weeks, and the plasma testosterone concentrations once a week. In the control and the two photoperiodic-treated groups, a treatment×time interaction was detected for testicular weight and plasma testosterone concentrations (P<0.001). In control bucks, testicular weight increased from January and peaked in June, whereas in both photoperiodic-treated groups, this variable increased from January, but peaked in April, when the values were higher than in controls (P<0.05). In the control group, plasma testosterone concentrations remained low from January to June, whereas in both photoperiodic-treated groups, this variable remained low from January to March; thereafter, these levels increased in both photoperiodic-treated groups, and were higher than controls in April and May (P<0.05). We conclude that continuous light after a long-day treatment stimulate testosterone secretion in Alpine male goats during the non-breeding season as well as the long days followed by a melatonin treatment. Therefore, continuous light could replace the implants of melatonin. PMID:26527165

  8. Continuous light after a long-day treatment is equivalent to melatonin implants to stimulate testosterone secretion in Alpine male goats.

    PubMed

    Delgadillo, J A; Vélez, L I; Flores, J A

    2016-04-01

    In rams, artificial long days followed by continuous light stimulate testosterone secretion during the non-breeding season. The objective of this study was to determine whether artificial long days followed by continuous light could stimulate testosterone secretion in Alpine bucks as well as in those exposed to long days followed by a melatonin treatment. All bucks were kept in shaded open pens. Control males were exposed to natural photoperiod conditions (n=5). Males of the two experimental groups were exposed to 2.5 months of long days from 1 December (n=5 each). On 16 February, one group of males was exposed to 24 h of light per day until 30 June; the other group was exposed to natural variations of photoperiod and received two s.c. melatonin implants. Testicular weight was determined every 2 weeks, and the plasma testosterone concentrations once a week. In the control and the two photoperiodic-treated groups, a treatment×time interaction was detected for testicular weight and plasma testosterone concentrations (P<0.001). In control bucks, testicular weight increased from January and peaked in June, whereas in both photoperiodic-treated groups, this variable increased from January, but peaked in April, when the values were higher than in controls (P<0.05). In the control group, plasma testosterone concentrations remained low from January to June, whereas in both photoperiodic-treated groups, this variable remained low from January to March; thereafter, these levels increased in both photoperiodic-treated groups, and were higher than controls in April and May (P<0.05). We conclude that continuous light after a long-day treatment stimulate testosterone secretion in Alpine male goats during the non-breeding season as well as the long days followed by a melatonin treatment. Therefore, continuous light could replace the implants of melatonin.

  9. Intracranial electrode implantation produces regional neuroinflammation and memory deficits in rats

    SciTech Connect

    Kuttner-Hirshler, Y.; Biegon, A.; Kuttner-Hirshler, Y.; Polat, U.; Biegon, A.

    2009-12-21

    Deep brain stimulation (DBS) is an established treatment for advanced Parkinson's disease (PD). The procedure entails intracranial implantation of an electrode in a specific brain structure followed by chronic stimulation. Although the beneficial effects of DBS on motor symptoms in PD are well known, it is often accompanied by cognitive impairments, the origin of which is not fully understood. To explore the possible contribution of the surgical procedure itself, we studied the effect of electrode implantation in the subthalamic nucleus (STN) on regional neuroinflammation and memory function in rats implanted bilaterally with stainless steel electrodes. Age-matched sham and intact rats were used as controls. Brains were removed 1 or 8 weeks post-implantation and processed for in vitro autoradiography with [(3)H]PK11195, an established marker of microglial activation. Memory function was assessed by the novel object recognition test (ORT) before surgery and 2 and 8 weeks after surgery. Electrode implantation produced region-dependent changes in ligand binding density in the implanted brains at 1 as well as 8 weeks post-implantation. Cortical regions showed more intense and widespread neuroinflammation than striatal or thalamic structures. Furthermore, implanted animals showed deficits in ORT performance 2 and 8 weeks post-implantation. Thus, electrode implantation resulted in a widespread and persistent neuroinflammation and sustained memory impairment. These results suggest that the insertion and continued presence of electrodes in the brain, even without stimulation, may lead to inflammation-mediated cognitive deficits in susceptible individuals, as observed in patients treated with DBS.

  10. Improved cartilage regeneration by implantation of acellular biomaterials after bone marrow stimulation: a systematic review and meta-analysis of animal studies

    PubMed Central

    Pot, Michiel W.; Gonzales, Veronica K.; Buma, Pieter; IntHout, Joanna

    2016-01-01

    Microfracture surgery may be applied to treat cartilage defects. During the procedure the subchondral bone is penetrated, allowing bone marrow-derived mesenchymal stem cells to migrate towards the defect site and form new cartilage tissue. Microfracture surgery generally results in the formation of mechanically inferior fibrocartilage. As a result, this technique offers only temporary clinical improvement. Tissue engineering and regenerative medicine may improve the outcome of microfracture surgery. Filling the subchondral defect with a biomaterial may provide a template for the formation of new hyaline cartilage tissue. In this study, a systematic review and meta-analysis were performed to assess the current evidence for the efficacy of cartilage regeneration in preclinical models using acellular biomaterials implanted after marrow stimulating techniques (microfracturing and subchondral drilling) compared to the natural healing response of defects. The review aims to provide new insights into the most effective biomaterials, to provide an overview of currently existing knowledge, and to identify potential lacunae in current studies to direct future research. A comprehensive search was systematically performed in PubMed and EMBASE (via OvidSP) using search terms related to tissue engineering, cartilage and animals. Primary studies in which acellular biomaterials were implanted in osteochondral defects in the knee or ankle joint in healthy animals were included and study characteristics tabulated (283 studies out of 6,688 studies found). For studies comparing non-treated empty defects to defects containing implanted biomaterials and using semi-quantitative histology as outcome measure, the risk of bias (135 studies) was assessed and outcome data were collected for meta-analysis (151 studies). Random-effects meta-analyses were performed, using cartilage regeneration as outcome measure on an absolute 0–100% scale. Implantation of acellular biomaterials significantly

  11. Improved cartilage regeneration by implantation of acellular biomaterials after bone marrow stimulation: a systematic review and meta-analysis of animal studies.

    PubMed

    Pot, Michiel W; Gonzales, Veronica K; Buma, Pieter; IntHout, Joanna; van Kuppevelt, Toin H; de Vries, Rob B M; Daamen, Willeke F

    2016-01-01

    Microfracture surgery may be applied to treat cartilage defects. During the procedure the subchondral bone is penetrated, allowing bone marrow-derived mesenchymal stem cells to migrate towards the defect site and form new cartilage tissue. Microfracture surgery generally results in the formation of mechanically inferior fibrocartilage. As a result, this technique offers only temporary clinical improvement. Tissue engineering and regenerative medicine may improve the outcome of microfracture surgery. Filling the subchondral defect with a biomaterial may provide a template for the formation of new hyaline cartilage tissue. In this study, a systematic review and meta-analysis were performed to assess the current evidence for the efficacy of cartilage regeneration in preclinical models using acellular biomaterials implanted after marrow stimulating techniques (microfracturing and subchondral drilling) compared to the natural healing response of defects. The review aims to provide new insights into the most effective biomaterials, to provide an overview of currently existing knowledge, and to identify potential lacunae in current studies to direct future research. A comprehensive search was systematically performed in PubMed and EMBASE (via OvidSP) using search terms related to tissue engineering, cartilage and animals. Primary studies in which acellular biomaterials were implanted in osteochondral defects in the knee or ankle joint in healthy animals were included and study characteristics tabulated (283 studies out of 6,688 studies found). For studies comparing non-treated empty defects to defects containing implanted biomaterials and using semi-quantitative histology as outcome measure, the risk of bias (135 studies) was assessed and outcome data were collected for meta-analysis (151 studies). Random-effects meta-analyses were performed, using cartilage regeneration as outcome measure on an absolute 0-100% scale. Implantation of acellular biomaterials significantly

  12. Improved cartilage regeneration by implantation of acellular biomaterials after bone marrow stimulation: a systematic review and meta-analysis of animal studies.

    PubMed

    Pot, Michiel W; Gonzales, Veronica K; Buma, Pieter; IntHout, Joanna; van Kuppevelt, Toin H; de Vries, Rob B M; Daamen, Willeke F

    2016-01-01

    Microfracture surgery may be applied to treat cartilage defects. During the procedure the subchondral bone is penetrated, allowing bone marrow-derived mesenchymal stem cells to migrate towards the defect site and form new cartilage tissue. Microfracture surgery generally results in the formation of mechanically inferior fibrocartilage. As a result, this technique offers only temporary clinical improvement. Tissue engineering and regenerative medicine may improve the outcome of microfracture surgery. Filling the subchondral defect with a biomaterial may provide a template for the formation of new hyaline cartilage tissue. In this study, a systematic review and meta-analysis were performed to assess the current evidence for the efficacy of cartilage regeneration in preclinical models using acellular biomaterials implanted after marrow stimulating techniques (microfracturing and subchondral drilling) compared to the natural healing response of defects. The review aims to provide new insights into the most effective biomaterials, to provide an overview of currently existing knowledge, and to identify potential lacunae in current studies to direct future research. A comprehensive search was systematically performed in PubMed and EMBASE (via OvidSP) using search terms related to tissue engineering, cartilage and animals. Primary studies in which acellular biomaterials were implanted in osteochondral defects in the knee or ankle joint in healthy animals were included and study characteristics tabulated (283 studies out of 6,688 studies found). For studies comparing non-treated empty defects to defects containing implanted biomaterials and using semi-quantitative histology as outcome measure, the risk of bias (135 studies) was assessed and outcome data were collected for meta-analysis (151 studies). Random-effects meta-analyses were performed, using cartilage regeneration as outcome measure on an absolute 0-100% scale. Implantation of acellular biomaterials significantly

  13. Improved cartilage regeneration by implantation of acellular biomaterials after bone marrow stimulation: a systematic review and meta-analysis of animal studies

    PubMed Central

    Pot, Michiel W.; Gonzales, Veronica K.; Buma, Pieter; IntHout, Joanna

    2016-01-01

    Microfracture surgery may be applied to treat cartilage defects. During the procedure the subchondral bone is penetrated, allowing bone marrow-derived mesenchymal stem cells to migrate towards the defect site and form new cartilage tissue. Microfracture surgery generally results in the formation of mechanically inferior fibrocartilage. As a result, this technique offers only temporary clinical improvement. Tissue engineering and regenerative medicine may improve the outcome of microfracture surgery. Filling the subchondral defect with a biomaterial may provide a template for the formation of new hyaline cartilage tissue. In this study, a systematic review and meta-analysis were performed to assess the current evidence for the efficacy of cartilage regeneration in preclinical models using acellular biomaterials implanted after marrow stimulating techniques (microfracturing and subchondral drilling) compared to the natural healing response of defects. The review aims to provide new insights into the most effective biomaterials, to provide an overview of currently existing knowledge, and to identify potential lacunae in current studies to direct future research. A comprehensive search was systematically performed in PubMed and EMBASE (via OvidSP) using search terms related to tissue engineering, cartilage and animals. Primary studies in which acellular biomaterials were implanted in osteochondral defects in the knee or ankle joint in healthy animals were included and study characteristics tabulated (283 studies out of 6,688 studies found). For studies comparing non-treated empty defects to defects containing implanted biomaterials and using semi-quantitative histology as outcome measure, the risk of bias (135 studies) was assessed and outcome data were collected for meta-analysis (151 studies). Random-effects meta-analyses were performed, using cartilage regeneration as outcome measure on an absolute 0–100% scale. Implantation of acellular biomaterials significantly

  14. The effect of step-synchronized vibration on patients with Parkinson's disease: case studies on subjects with freezing of gait or an implanted deep brain stimulator.

    PubMed

    Winfree, Kyle N; Pretzer-Aboff, Ingrid; Hilgart, David; Aggarwal, Rajeev; Behari, Madhuri; Agrawal, Sunil K

    2013-09-01

    Identifying noninvasive treatments to alleviate the symptoms of Parkinson's disease (PD) is important to improving the quality of life for those with PD. Several studies have explored the effects of visual, auditory, and vibratory cueing to improve gait in PD patients. Here, we present a wireless vibratory feedback system, called the PDShoe, and an associated intervention study with four subjects. The PDShoe was used on two control subjects, one subject with PD who experienced freezing of gait (FOG), and one subject with PD with an implanted deep brain stimulator (DBS). This short intervention study showed statistically significant improvements in peak heel pressure timing, peak toe pressure timing, time on the heel sensor, and stance to swing ratio after just one week of twice-daily therapy. Thus, step-synchronized vibration applied to the feet of patients with PD may be an effective way to improve gait in those subjects.

  15. Stimulation by cochlear implant in unilaterally deaf rats reverses the decrease of inhibitory transmission in the inferior colliculus.

    PubMed

    Argence, Meritxell; Vassias, Isabelle; Kerhuel, Lubin; Vidal, Pierre-Paul; de Waele, Catherine

    2008-10-01

    In the last decade, numerous studies have investigated synaptic transmission changes in various auditory nuclei after unilateral cochlear injury. However, few data are available concerning the potential effect of electrical stimulation of the deafferented auditory nerve on the inhibitory neurotransmission in these nuclei. We report here for the first time the effect of chronic electrical stimulation of the deafferented auditory nerve on alpha1 subunit of the glycinergic receptor (GlyRalpha1) and glutamic acid decarboxylase (GAD)67 expression in the central nucleus of inferior colliculus (CIC). Adult rats were unilaterally cochleectomized by intracochlear neomycin sulphate injection. Fifteen days later, the ipsilateral auditory nerve was chronically stimulated either 4, 8 or 22 h daily, for 5 days using intracochlear bipolar electrodes. GlyRalpha1 and GAD67 mRNA and protein were quantified in the CIC using in situ hybridization and immunohistofluorescence methods. Our data showed that as after surgical ablation, GlyRalpha1 and GAD67 expression were strongly decreased in the contralateral CIC after unilateral chemical cochleectomy. Most importantly, these postlesional down-modulations were significantly reversed by chronic electrical stimulation of the deafferented auditory nerve. This recovery, however, did not persist for more than 5 days after the cessation of the deafferented auditory nerve electrical stimulation. Thus, downregulations of GlyRalpha1 and GAD67 may be involved both in the increased excitability observed in the CIC after unilateral deafness and consequently in the tinnitus frequently observed in unilateral adult deaf patients. Electrical stimulation of the deafferented auditory nerve in patients may be a potential new approach for treating tinnitus with unilateral hearing loss. PMID:18973578

  16. Fully committed.

    PubMed

    Chowdhury, R

    1997-01-01

    In India, HIV/AIDS is spreading rapidly because of high-risk heterosexual behavior and IV drug use. The Indian government has responded to the epidemic by creating a National AIDS Control Program in 1987 and a National AIDS Control Organization in 1992, which implemented a 5-year strategic play at the cost of Rs. 2.8 billion. The national program sought to 1) prevent and control sexually transmitted disease, 2) ensure the safety of the blood supply, 3) strengthen program management capabilities, 4) stimulate social mobilization, 5) launch an intensive national health communications campaign focussed on the needs of the rural population, 6) train physicians in the clinical management of HIV/AIDS, and 7) create 107 sentinel HIV surveillance sites. The achievements of this program during the past 5 years have revealed areas that require an expanded response. India is promoting condom use through social marketing, improving family counseling and clinical management of hospitalized AIDS patients, intensifying research to discover treatment modalities within the tradition of indigenous medicine, and taking measures to prevent social discrimination of HIV-infected people. The National AIDS Control Program for 1997-2002 will prioritize empowerment of women and protection of infected children through a multisectoral approach. The Indian government is currently negotiating with the World Bank for a second loan to cover the continuation of this program and pledges to join other nations in the battle against HIV/AIDS.

  17. Collective review: bioactive implants coated with poly(D,L-lactide) and growth factors IGF-I, TGF-beta1, or BMP-2 for stimulation of fracture healing.

    PubMed

    Schmidmaier, Gerhard; Lucke, Martin; Schwabe, Philipp; Raschke, Michael; Haas, Norbert P; Wildemann, Britt

    2006-01-01

    Demographic data reveal that due to the increasing aging of the population, complications with the musculoskeletal system will increase in the next years. One major problem in orthopedic and trauma surgery are the delayed healing or non-unions of long bone fractures. The exogenous application of growth factors can stimulate the bone healing to reduce these complications. Beside the choice of the optimal growth factor the application system is important. Therefore, we developed a new bioactive coating method for implants, which is based on a biodegradable poly(D,L-lactide) (coating thickness: 10 mum). This coating allows the incorporation of growth factors and the controlled release of these factors during the healing process without the need for further devices. The effect of different growth factors (IGF-I, TGF-beta1, and BMP-2) locally released from coated intramedullary implants on fracture healing was investigated with biomechanical and histological analysis in rats. All investigated growth factors stimulated the fracture healing as assessed with biomechanical tests and histological analysis. The local application of combined IGF-I and TGF-beta1 had the most stimulating effect on fracture healing, followed by the effect of BMP-2, IGF-I, and TGF-beta1 alone. Bioactive coating of biomechanical well-established implants can on the one hand stabilize the fracture and on the other hand stimulate healing processes to increase healing and to reduce the rate of complications.

  18. Integrated approach for smart implantable cardioverter defibrillator (ICD) device with real time ECG monitoring: use of flexible sensors for localized arrhythmia sensing and stimulation

    PubMed Central

    Puri, Munish; Chapalamadugu, Kalyan C.; Miranda, Aimon C.; Gelot, Shyam; Moreno, Wilfrido; Adithya, Prashanth C.; Law, Catherine; Tipparaju, Srinivas M.

    2013-01-01

    Arrhythmias are the most common cause of death associated with sudden death and are common in US and worldwide. Cardiac resynchronization therapy (CRT), evolving from pacemakers and development of implantable cardioverter defibrillator (ICD), has been adopted for therapeutic use and demonstrated benefits in patients over the years due to its design and intricate functionality. Recent research has been focused on significant design improvement and efforts are dedicated toward device size reduction, weight and functionality in commercially available ICD's since its invention in the 1960's. Commercially available CRT-D has shown advancement on both clinical and technical side. However, improved focus is required on the device miniaturization, technologically supported and integrated wireless based system for real time heart monitoring electrocardiogram (ECG). In the present report a concise overview for the state-of-the art technology in ICDs and avenues for future development are presented. A unique perspective is also included for ICD device miniaturization and integration of flexible sensing array. Sensor array integration along with its capabilities for identifying localized arrhythmia detection and targeted stimulation for enhancing ICD device capabilities is reviewed. PMID:24167492

  19. Self-Tracking Energy Transfer for Neural Stimulation in Untethered Mice

    NASA Astrophysics Data System (ADS)

    Ho, John S.; Tanabe, Yuji; Iyer, Shrivats Mohan; Christensen, Amelia J.; Grosenick, Logan; Deisseroth, Karl; Delp, Scott L.; Poon, Ada S. Y.

    2015-08-01

    Optical or electrical stimulation of neural circuits in mice during natural behavior is an important paradigm for studying brain function. Conventional systems for optogenetics and electrical microstimulation require tethers or large head-mounted devices that disrupt animal behavior. We report a method for wireless powering of small-scale implanted devices based on the strong localization of energy that occurs during resonant interaction between a radio-frequency cavity and intrinsic modes in mice. The system features self-tracking over a wide (16-cm diameter) operational area, and is used to demonstrate wireless activation of cortical neurons with miniaturized stimulators (10 mm3 , 20 mg) fully implanted under the skin.

  20. Nanotechnology and dental implants.

    PubMed

    Lavenus, Sandrine; Louarn, Guy; Layrolle, Pierre

    2010-01-01

    The long-term clinical success of dental implants is related to their early osseointegration. This paper reviews the different steps of the interactions between biological fluids, cells, tissues, and surfaces of implants. Immediately following implantation, implants are in contact with proteins and platelets from blood. The differentiation of mesenchymal stem cells will then condition the peri-implant tissue healing. Direct bone-to-implant contact is desired for a biomechanical anchoring of implants to bone rather than fibrous tissue encapsulation. Surfaces properties such as chemistry and roughness play a determinant role in these biological interactions. Physicochemical features in the nanometer range may ultimately control the adsorption of proteins as well as the adhesion and differentiation of cells. Nanotechnologies are increasingly used for surface modifications of dental implants. Another approach to enhance osseointegration is the application of thin calcium phosphate (CaP) coatings. Bioactive CaP nanocrystals deposited on titanium implants are resorbable and stimulate bone apposition and healing. Future nanometer-controlled surfaces may ultimately direct the nature of peri-implant tissues and improve their clinical success rate.

  1. Nanotechnology and Dental Implants

    PubMed Central

    Lavenus, Sandrine; Louarn, Guy; Layrolle, Pierre

    2010-01-01

    The long-term clinical success of dental implants is related to their early osseointegration. This paper reviews the different steps of the interactions between biological fluids, cells, tissues, and surfaces of implants. Immediately following implantation, implants are in contact with proteins and platelets from blood. The differentiation of mesenchymal stem cells will then condition the peri-implant tissue healing. Direct bone-to-implant contact is desired for a biomechanical anchoring of implants to bone rather than fibrous tissue encapsulation. Surfaces properties such as chemistry and roughness play a determinant role in these biological interactions. Physicochemical features in the nanometer range may ultimately control the adsorption of proteins as well as the adhesion and differentiation of cells. Nanotechnologies are increasingly used for surface modifications of dental implants. Another approach to enhance osseointegration is the application of thin calcium phosphate (CaP) coatings. Bioactive CaP nanocrystals deposited on titanium implants are resorbable and stimulate bone apposition and healing. Future nanometer-controlled surfaces may ultimately direct the nature of peri-implant tissues and improve their clinical success rate. PMID:21253543

  2. Estimating dose to implantable cardioverter-defibrillator outside the treatment fields using a skin QED diode, optically stimulated luminescent dosimeters, and LiF thermoluminescent dosimeters.

    PubMed

    Chan, Maria F; Song, Yulin; Dauer, Lawrence T; Li, Jingdong; Huang, David; Burman, Chandra

    2012-01-01

    The purpose of this work was to determine the relative sensitivity of skin QED diodes, optically stimulated luminescent dosimeters (OSLDs) (microStar™ DOT, Landauer), and LiF thermoluminescent dosimeters (TLDs) as a function of distance from a photon beam field edge when applied to measure dose at out-of-field points. These detectors have been used to estimate radiation dose to patients' implantable cardioverter-defibrillators (ICDs) located outside the treatment field. The ICDs have a thin outer case made of 0.4- to 0.6-mm-thick titanium (∼2.4-mm tissue equivalent). A 5-mm bolus, being the equivalent depth of the devices under the patient's skin, was placed over the ICDs. Response per unit absorbed dose-to-water was measured for each of the dosimeters with and without bolus on the beam central axis (CAX) and at a distance up to 20 cm from the CAX. Doses were measured with an ionization chamber at various depths for 6- and 15-MV x-rays on a Varian Clinac-iX linear accelerator. Relative sensitivity of the detectors was determined as the ratio of the sensitivity at each off-axis distance to that at the CAX. The detector sensitivity as a function of the distance from the field edge changed by ± 3% (1-11%) for LiF TLD-700, decreased by 10% (5-21%) for OSLD, and increased by 16% (11-19%) for the skin QED diode (Sun Nuclear Corp.) at the equivalent depth of 5 mm for 6- or 15-MV photon energies. Our results showed that the use of bolus with proper thickness (i.e., ∼d(max) of the photon energy) on the top of the ICD would reduce the scattered dose to a lower level. Dosimeters should be calibrated out-of-field and preferably with bolus equal in thickness to the depth of interest. This can be readily performed in clinic.

  3. Estimating dose to implantable cardioverter-defibrillator outside the treatment fields using a skin QED diode, optically stimulated luminescent dosimeters, and LiF thermoluminescent dosimeters

    SciTech Connect

    Chan, Maria F.; Song, Yulin; Dauer, Lawrence T.; Li Jingdong; Huang, David; Burman, Chandra

    2012-10-01

    The purpose of this work was to determine the relative sensitivity of skin QED diodes, optically stimulated luminescent dosimeters (OSLDs) (microStar Trade-Mark-Sign DOT, Landauer), and LiF thermoluminescent dosimeters (TLDs) as a function of distance from a photon beam field edge when applied to measure dose at out-of-field points. These detectors have been used to estimate radiation dose to patients' implantable cardioverter-defibrillators (ICDs) located outside the treatment field. The ICDs have a thin outer case made of 0.4- to 0.6-mm-thick titanium ({approx}2.4-mm tissue equivalent). A 5-mm bolus, being the equivalent depth of the devices under the patient's skin, was placed over the ICDs. Response per unit absorbed dose-to-water was measured for each of the dosimeters with and without bolus on the beam central axis (CAX) and at a distance up to 20 cm from the CAX. Doses were measured with an ionization chamber at various depths for 6- and 15-MV x-rays on a Varian Clinac-iX linear accelerator. Relative sensitivity of the detectors was determined as the ratio of the sensitivity at each off-axis distance to that at the CAX. The detector sensitivity as a function of the distance from the field edge changed by {+-} 3% (1-11%) for LiF TLD-700, decreased by 10% (5-21%) for OSLD, and increased by 16% (11-19%) for the skin QED diode (Sun Nuclear Corp.) at the equivalent depth of 5 mm for 6- or 15-MV photon energies. Our results showed that the use of bolus with proper thickness (i.e., {approx}d{sub max} of the photon energy) on the top of the ICD would reduce the scattered dose to a lower level. Dosimeters should be calibrated out-of-field and preferably with bolus equal in thickness to the depth of interest. This can be readily performed in clinic.

  4. 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…

  5. [Implantation of collagen coated hydroxyapatite particles. A clinical-histological study in humans].

    PubMed

    Sanz, M; Bascones, A; Kessler, A; García Nuñez, J; Newman, M G; Robertson, M A; Carranza, F A

    1989-05-01

    In this study, histologic behaviour of collagen coated hydroxylapatite particles implanted in human periodontal osseous defects has been analyzed. This material was surgically implanted in four patients, and reentry and block biopsies were carried out 4 and 6 months later. The histologic results demonstrate that this material is well tolerated by surrounding tissues, not eliciting an inflammatory reaction. At four months, the hydroxylapatite particles appear encapsulated by a very cellular connective tissue and at 6 months are found in direct contact with osteoid and mature bone. This material acts as a filler material, being fully biocompatible and stimulating an osseoconductive reaction of the adjacent alveolar bone. PMID:2637052

  6. [Implantation of collagen coated hydroxyapatite particles. A clinical-histological study in humans].

    PubMed

    Sanz, M; Bascones, A; Kessler, A; García Nuñez, J; Newman, M G; Robertson, M A; Carranza, F A

    1989-05-01

    In this study, histologic behaviour of collagen coated hydroxylapatite particles implanted in human periodontal osseous defects has been analyzed. This material was surgically implanted in four patients, and reentry and block biopsies were carried out 4 and 6 months later. The histologic results demonstrate that this material is well tolerated by surrounding tissues, not eliciting an inflammatory reaction. At four months, the hydroxylapatite particles appear encapsulated by a very cellular connective tissue and at 6 months are found in direct contact with osteoid and mature bone. This material acts as a filler material, being fully biocompatible and stimulating an osseoconductive reaction of the adjacent alveolar bone.

  7. Dental Implants

    MedlinePlus

    ... Procedures Dental Implants Dentures Direct Bonding Implants versus Bridges Orthodontics and Aligners Periodontal Plastic Surgery Porcelain Crowns Porcelain Fixed Bridges Porcelain Veneers Repairing Chipped Teeth Teeth Whitening Tooth- ...

  8. Implantable electrical device

    NASA Technical Reports Server (NTRS)

    Jhabvala, M. D. (Inventor)

    1982-01-01

    A fully implantable and self contained device is disclosed composed of a flexible electrode array for surrounding damaged nerves and a signal generator for driving the electrode array with periodic electrical impulses of nanoampere magnitude to induce regeneration of the damaged nerves.

  9. Electrical stimulation of a small brain area reversibly disrupts consciousness.

    PubMed

    Koubeissi, Mohamad Z; Bartolomei, Fabrice; Beltagy, Abdelrahman; Picard, Fabienne

    2014-08-01

    The neural mechanisms that underlie consciousness are not fully understood. We describe a region in the human brain where electrical stimulation reproducibly disrupted consciousness. A 54-year-old woman with intractable epilepsy underwent depth electrode implantation and electrical stimulation mapping. The electrode whose stimulation disrupted consciousness was between the left claustrum and anterior-dorsal insula. Stimulation of electrodes within 5mm did not affect consciousness. We studied the interdependencies among depth recording signals as a function of time by nonlinear regression analysis (h(2) coefficient) during stimulations that altered consciousness and stimulations of the same electrode at lower current intensities that were asymptomatic. Stimulation of the claustral electrode reproducibly resulted in a complete arrest of volitional behavior, unresponsiveness, and amnesia without negative motor symptoms or mere aphasia. The disruption of consciousness did not outlast the stimulation and occurred without any epileptiform discharges. We found a significant increase in correlation for interactions affecting medial parietal and posterior frontal channels during stimulations that disrupted consciousness compared with those that did not. Our findings suggest that the left claustrum/anterior insula is an important part of a network that subserves consciousness and that disruption of consciousness is related to increased EEG signal synchrony within frontal-parietal networks.

  10. Electrical stimulation of a small brain area reversibly disrupts consciousness.

    PubMed

    Koubeissi, Mohamad Z; Bartolomei, Fabrice; Beltagy, Abdelrahman; Picard, Fabienne

    2014-08-01

    The neural mechanisms that underlie consciousness are not fully understood. We describe a region in the human brain where electrical stimulation reproducibly disrupted consciousness. A 54-year-old woman with intractable epilepsy underwent depth electrode implantation and electrical stimulation mapping. The electrode whose stimulation disrupted consciousness was between the left claustrum and anterior-dorsal insula. Stimulation of electrodes within 5mm did not affect consciousness. We studied the interdependencies among depth recording signals as a function of time by nonlinear regression analysis (h(2) coefficient) during stimulations that altered consciousness and stimulations of the same electrode at lower current intensities that were asymptomatic. Stimulation of the claustral electrode reproducibly resulted in a complete arrest of volitional behavior, unresponsiveness, and amnesia without negative motor symptoms or mere aphasia. The disruption of consciousness did not outlast the stimulation and occurred without any epileptiform discharges. We found a significant increase in correlation for interactions affecting medial parietal and posterior frontal channels during stimulations that disrupted consciousness compared with those that did not. Our findings suggest that the left claustrum/anterior insula is an important part of a network that subserves consciousness and that disruption of consciousness is related to increased EEG signal synchrony within frontal-parietal networks. PMID:24967698

  11. Design, fabrication and perivascular implantation of bioactive scaffolds engineered with human adventitial progenitor cells for stimulation of arteriogenesis in peripheral ischemia.

    PubMed

    Carrabba, M; De Maria, C; Oikawa, A; Reni, C; Rodriguez-Arabaolaza, I; Spencer, H; Slater, S; Avolio, E; Dang, Z; Spinetti, G; Madeddu, P; Vozzi, G

    2016-03-01

    Cell therapy represents a promising option for revascularization of ischemic tissues. However, injection of dispersed cells is not optimal to ensure precise homing into the recipient's vasculature. Implantation of cell-engineered scaffolds around the occluded artery may obviate these limitations. Here, we employed the synthetic polymer polycaprolactone for fabrication of 3D woodpile- or channel-shaped scaffolds by a computer-assisted writing system (pressure assisted micro-syringe square), followed by deposition of gelatin (GL) nanofibers by electro-spinning. Scaffolds were then cross-linked with natural (genipin, GP) or synthetic (3-glycidyloxy-propyl-trimethoxy-silane, GPTMS) agents to improve mechanical properties and durability in vivo. The composite scaffolds were next fixed by crown inserts in each well of a multi-well plate and seeded with adventitial progenitor cells (APCs, 3 cell lines in duplicate), which were isolated/expanded from human saphenous vein surgical leftovers. Cell density, alignment, proliferation and viability were assessed 1 week later. Data from in vitro assays showed channel-shaped/GPTMS-crosslinked scaffolds confer APCs with best alignment and survival/growth characteristics. Based on these results, channel-shaped/GPTMS-crosslinked scaffolds with or without APCs were implanted around the femoral artery of mice with unilateral limb ischemia. Perivascular implantation of scaffolds accelerated limb blood flow recovery, as assessed by laser Doppler or fluorescent microspheres, and increased arterial collaterals around the femoral artery and in limb muscles compared with non-implanted controls. Blood flow recovery and perivascular arteriogenesis were additionally incremented by APC-engineered scaffolds. In conclusion, perivascular application of human APC-engineered scaffolds may represent a novel option for targeted delivery of therapeutic cells in patients with critical limb ischemia. PMID:27011300

  12. Design, fabrication and perivascular implantation of bioactive scaffolds engineered with human adventitial progenitor cells for stimulation of arteriogenesis in peripheral ischemia.

    PubMed

    Carrabba, M; De Maria, C; Oikawa, A; Reni, C; Rodriguez-Arabaolaza, I; Spencer, H; Slater, S; Avolio, E; Dang, Z; Spinetti, G; Madeddu, P; Vozzi, G

    2016-03-01

    Cell therapy represents a promising option for revascularization of ischemic tissues. However, injection of dispersed cells is not optimal to ensure precise homing into the recipient's vasculature. Implantation of cell-engineered scaffolds around the occluded artery may obviate these limitations. Here, we employed the synthetic polymer polycaprolactone for fabrication of 3D woodpile- or channel-shaped scaffolds by a computer-assisted writing system (pressure assisted micro-syringe square), followed by deposition of gelatin (GL) nanofibers by electro-spinning. Scaffolds were then cross-linked with natural (genipin, GP) or synthetic (3-glycidyloxy-propyl-trimethoxy-silane, GPTMS) agents to improve mechanical properties and durability in vivo. The composite scaffolds were next fixed by crown inserts in each well of a multi-well plate and seeded with adventitial progenitor cells (APCs, 3 cell lines in duplicate), which were isolated/expanded from human saphenous vein surgical leftovers. Cell density, alignment, proliferation and viability were assessed 1 week later. Data from in vitro assays showed channel-shaped/GPTMS-crosslinked scaffolds confer APCs with best alignment and survival/growth characteristics. Based on these results, channel-shaped/GPTMS-crosslinked scaffolds with or without APCs were implanted around the femoral artery of mice with unilateral limb ischemia. Perivascular implantation of scaffolds accelerated limb blood flow recovery, as assessed by laser Doppler or fluorescent microspheres, and increased arterial collaterals around the femoral artery and in limb muscles compared with non-implanted controls. Blood flow recovery and perivascular arteriogenesis were additionally incremented by APC-engineered scaffolds. In conclusion, perivascular application of human APC-engineered scaffolds may represent a novel option for targeted delivery of therapeutic cells in patients with critical limb ischemia.

  13. CHAPTER: In-Situ Characterization of Stimulating Microelectrode Arrays: Study of an Idealized Structure Based on Argus II Retinal implantsBOOK TITLE: Implantable Neural Prostheses 2: Techniques and Engineering Approaches, D.M. Zhou and E. Greenbaum, Eds., Springer, NY 2009

    SciTech Connect

    Greenbaum, Elias; Sanders, Charlene A; Kandagor, Vincent

    2010-01-01

    The development of a retinal prosthesis for artificial sight includes a study of the factors affecting the structural and functional stability of chronically implanted microelectrode arrays. Although neuron depolarization and propagation of electrical signals have been studied for nearly a century, the use of multielectrode stimulation as a proposed therapy to treat blindness is a frontier area of modern ophthalmology research. Mapping and characterizing the topographic information contained in the electric field potentials and understanding how this information is transmitted and interpreted in the visual cortex is still very much a work in progress. In order to characterize the electrical field patterns generated by the device, an in vitro prototype that mimics several of the physical and chemical parameters of the in vivo visual implant device was fabricated. We carried out multiple electrical measurements in a model 'eye,' beginning with a single electrode, followed by a 9-electrode array structure, both idealized components based on the Argus II retinal implants. Correlating the information contained in the topographic features of the electric fields with psychophysical testing in patients may help reduce the time required for patients to convert the electrical patterns into graphic signals.

  14. Preliminary Studies on Base Substitutions and Repair of DNA Mismatch Damage Stimulated by Low Energy N+ Ion Beam Implantation in Escherichia coli

    NASA Astrophysics Data System (ADS)

    Xie, Chuan-xiao; Guo, Jin-hua; Cheng, Bei-jiu; Yu, Zeng-liang

    2003-02-01

    Ever since the low energy N+ ion beam has been accepted that the mutation effects of ionizing radiation are attributed mainly to direct or indirect damage to DNA. Evidences based on naked DNA irradiation in support of a mutation spectrum appears to be consistent, but direct proof of such results in vivo are limited. Using mutS, dam and/or dcm defective Eschericha coli mutator strains, an preliminary experimental system on induction of in vivo mutation spectra of low energy N+ ion beam has been established in this study. It was observed that the mutation rates of rifampicin resistance induced by N+ implantation were quite high, ranging from 9.2 × 10-8 to 4.9 × 10-5 at the dosage of 5.2 × 1014 ions/cm2. Strains all had more than 90-fold higher mutation rate than its spontaneous mutation rate determined by this method. It reveals that base substitutions involve in induction of mutation of low energy nitrogen ion beam implantation. The mutation rates of mutator strains were nearly 500-fold (GM2929), 400-fold (GM5864) and 6-fold larger than that of AB1157. The GM2929 and GM5864 both lose the ability of repair DNA mismatch damage by virtue of both dam and dcm pathways defective (GM2929) or failing to assemble the repair complex (GM5864) respectively. It may explain the both strains had a similar higher mutation rate than GM124 did. It indicated that DNA cytosine methylase might play an important role in mismatch repair of DNA damage induced by N+ implantation. The further related research were also discussed.

  15. Mobility implants: a review.

    PubMed

    Danz, W

    1990-01-01

    We present a brief review of mobility implants, their contribution, and the experiences derived after almost 40 years since the new concepts of full mobility implants were introduced. In early 1940, experiments with a new material for the making of plastic artificial eyes was also being considered for the making of orbital implants. Methyl-methacrylate (MMA) had proven inert and satisfactory for dental products. The Surgeon Generals office of the Armed Services encouraged further research and experimental work in the development of plastic eyes. The success of the new material sponsored the beginning of great expansion with new concepts for orbital implants. Through a period of more than a decade, the design and types of implants went through three stages. First, the buried implant was introduced, then the exposed integrated followed, and the buried integrated subsequently followed. The path of progress was not smooth. Theoretically correct designs and surgical procedures met unexpected practical difficulties for the ophthalmic surgeon, the patient, and the eye maker. Surgical and technical efforts were carefully reviewed to eliminate the problems encountered, only to have further unforeseen complications arise. Infections, extrusions, and migration of the implant were not uncommon. The exposed integrated implant was eventually abandoned. However, there were some extraordinary successes of mobility. A new era introduced fully buried mobility implants that were more successful. However, this procedure also produced some problems, causing infection (or allergy), extrusion, and migration. Tantalum mesh and gauze gave great promise with the inception of their use. Orbital tissue grew into the material in an astonishing way, making it possible to secure the extraocular muscles and tenons.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Fully Regressive Melanoma

    PubMed Central

    Ehrsam, Eric; Kallini, Joseph R.; Lebas, Damien; Modiano, Philippe; Cotten, Hervé

    2016-01-01

    Fully regressive melanoma is a phenomenon in which the primary cutaneous melanoma becomes completely replaced by fibrotic components as a result of host immune response. Although 10 to 35 percent of cases of cutaneous melanomas may partially regress, fully regressive melanoma is very rare; only 47 cases have been reported in the literature to date. AH of the cases of fully regressive melanoma reported in the literature were diagnosed in conjunction with metastasis on a patient. The authors describe a case of fully regressive melanoma without any metastases at the time of its diagnosis. Characteristic findings on dermoscopy, as well as the absence of melanoma on final biopsy, confirmed the diagnosis.

  17. Fully Regressive Melanoma

    PubMed Central

    Ehrsam, Eric; Kallini, Joseph R.; Lebas, Damien; Modiano, Philippe; Cotten, Hervé

    2016-01-01

    Fully regressive melanoma is a phenomenon in which the primary cutaneous melanoma becomes completely replaced by fibrotic components as a result of host immune response. Although 10 to 35 percent of cases of cutaneous melanomas may partially regress, fully regressive melanoma is very rare; only 47 cases have been reported in the literature to date. AH of the cases of fully regressive melanoma reported in the literature were diagnosed in conjunction with metastasis on a patient. The authors describe a case of fully regressive melanoma without any metastases at the time of its diagnosis. Characteristic findings on dermoscopy, as well as the absence of melanoma on final biopsy, confirmed the diagnosis. PMID:27672418

  18. Electrical stimulation of the hypoglossal nerve in the treatment of obstructive sleep apnea.

    PubMed

    Kezirian, Eric J; Boudewyns, An; Eisele, David W; Schwartz, Alan R; Smith, Philip L; Van de Heyning, Paul H; De Backer, Wilfried A

    2010-10-01

    Upper airway occlusion in obstructive sleep apnea has been attributed to a decline in pharyngeal neuromuscular activity occurring in a structurally narrowed airway. Surgical treatment focuses on the correction of anatomic abnormalities, but there is a potential role for activation of the upper airway musculature, especially with stimulation of the hypoglossal nerve and genioglossus muscle. We present evidence from research on upper airway neuromuscular electrical stimulation in animals and humans. We also present results from eight obstructive sleep apnea patients with a fully implanted system for hypoglossal nerve stimulation, demonstrating an improvement in upper airway collapsibility and obstructive sleep apnea severity. Future research, including optimization of device features and stimulation parameters as well as patient selection, is necessary to make hypoglossal nerve stimulation a viable alternative to positive airway pressure therapy and upper airway surgical procedures.

  19. Electrical stimulation of the hypoglossal nerve: a potential therapy.

    PubMed

    Schwartz, Alan R; Smith, Philip L; Oliven, Arie

    2014-02-01

    Obstructive sleep apnea is characterized by recurrent episodes of pharyngeal collapse, which result from a decrease in pharyngeal dilator muscle tone. The genioglossus is a major pharyngeal dilator that maintains airway patency during sleep. Early studies in animal and humans have demonstrated that electrical stimulation of this muscle reduces pharyngeal collapsibility, increases airflow, and mitigates obstructive sleep apnea. These findings impelled the development of fully implantable hypoglossal nerve stimulating systems (HGNS), for which feasibility trial results are now available. These pilot studies have confirmed that hypoglossal nerve stimulation can prevent pharyngeal collapse without arousing patients from sleep. Potentially, a substantial segment of the patient population with obstructive sleep apnea can be treated with this novel approach. Furthermore, the feasibility trial findings suggest that the therapeutic potential of HGNS can be optimized by selecting patients judiciously, titrating the stimulus intensity optimally, and characterizing the underlying function and anatomy of the pharynx. These strategies are currently being examined in ongoing pivotal trials of HGNS.

  20. Cochlear Implants

    MedlinePlus

    ... electrodes are inserted. The electronic device at the base of the electrode array is then placed under ... FDA approval for implants The Food and Drug Administration (FDA) regulates cochlear implant devices for both adults ...

  1. Dental Implants.

    PubMed

    Zohrabian, Vahe M; Sonick, Michael; Hwang, Debby; Abrahams, James J

    2015-10-01

    Dental implants restore function to near normal in partially or completely edentulous patients. A root-form implant is the most frequently used type of dental implant today. The basis for dental implants is osseointegration, in which osteoblasts grow and directly integrate with the surface of titanium posts surgically embedded into the jaw. Radiologic assessment is critical in the preoperative evaluation of the dental implant patient, as the exact height, width, and contour of the alveolar ridge must be determined. Moreover, the precise locations of the maxillary sinuses and mandibular canals, as well as their relationships to the site of implant surgery must be ascertained. As such, radiologists must be familiar with implant design and surgical placement, as well as augmentation procedures utilized in those patients with insufficient bone in the maxilla and mandible to support dental implants.

  2. Immediate Return to Ambulation and Improved Functional Capacity for Rehabilitation in Complex Regional Pain Syndrome following Early Implantation of a Spinal Cord Stimulation System.

    PubMed

    Goff, Brandon Jesse; Naber, Jeremy Wingseng; McCallin, John Patrick; Lopez, Edward Michael; Guthmiller, Kevin Brant; Lautenschlager, Karl Alan; Lai, Tristan Toll; Hommer, Dean Harry; Marin, Gonzalez Raul

    2014-01-01

    Complex regional pain syndrome (CRPS) is a neuropathic pain condition that is characterized by vasomotor, sensory, sudomotor, and motor symptoms. Spinal cord stimulation (SCS) has been successfully utilized for the treatment of pain refractory to conventional therapies. We present a case of a previously highly functioning 54-year-old female who developed a rarely reported case of idiopathic CRPS of the right ankle which spontaneously occurred four months after an uncomplicated anterior cervical disc fusion. This condition resulted in severe pain and functional impairment that was unresponsive to pharmacological management. The patient's rehabilitation was severely stymied by her excruciating pain. However, with the initiation of spinal cord stimulation, her pain was adequately controlled allowing for progression to full unassisted ambulation, advancing functional capacity, and improving quality of life. This case report supports the concept that rapid progression to neuromodulation, rather than delays that occur due to attempts at serial sympathetic blocks, may better control symptoms leading allowing for a more meaningful recovery.

  3. Optical Stimulation of Neurons

    PubMed Central

    Thompson, Alexander C.; Stoddart, Paul R.; Jansen, E. Duco

    2014-01-01

    Our capacity to interface with the nervous system remains overwhelmingly reliant on electrical stimulation devices, such as electrode arrays and cuff electrodes that can stimulate both central and peripheral nervous systems. However, electrical stimulation has to deal with multiple challenges, including selectivity, spatial resolution, mechanical stability, implant-induced injury and the subsequent inflammatory response. Optical stimulation techniques may avoid some of these challenges by providing more selective stimulation, higher spatial resolution and reduced invasiveness of the device, while also avoiding the electrical artefacts that complicate recordings of electrically stimulated neuronal activity. This review explores the current status of optical stimulation techniques, including optogenetic methods, photoactive molecule approaches and infrared neural stimulation, together with emerging techniques such as hybrid optical-electrical stimulation, nanoparticle enhanced stimulation and optoelectric methods. Infrared neural stimulation is particularly emphasised, due to the potential for direct activation of neural tissue by infrared light, as opposed to techniques that rely on the introduction of exogenous light responsive materials. However, infrared neural stimulation remains imperfectly understood, and techniques for accurately delivering light are still under development. While the various techniques reviewed here confirm the overall feasibility of optical stimulation, a number of challenges remain to be overcome before they can deliver their full potential. PMID:26322269

  4. [Hearing implants].

    PubMed

    Stokroos, Robert J; George, Erwin L J

    2013-01-01

    In the Netherlands, more than 1.5 million people suffer from sensorineural hearing loss or deafness. However, fitting conventional hearing aids does not provide a solution for everyone. In recent decades, developments in medical technology have produced implantable and other devices that restore both sensorineural and conductive hearing losses. These hearing devices can be categorized into bone conductive devices, implantable middle ear prostheses, cochlear implants and auditory brainstem implants. Furthermore, new implants aimed at treating tinnitus and loss of vestibular function have recently been developed.

  5. Fully Integrated Biochip Platforms for Advanced Healthcare

    PubMed Central

    Carrara, Sandro; Ghoreishizadeh, Sara; Olivo, Jacopo; Taurino, Irene; Baj-Rossi, Camilla; Cavallini, Andrea; de Beeck, Maaike Op; Dehollain, Catherine; Burleson, Wayne; Moussy, Francis Gabriel; Guiseppi-Elie, Anthony; De Micheli, Giovanni

    2012-01-01

    Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications. PMID:23112644

  6. Fully integrated biochip platforms for advanced healthcare.

    PubMed

    Carrara, Sandro; Ghoreishizadeh, Sara; Olivo, Jacopo; Taurino, Irene; Baj-Rossi, Camilla; Cavallini, Andrea; de Beeck, Maaike Op; Dehollain, Catherine; Burleson, Wayne; Moussy, Francis Gabriel; Guiseppi-Elie, Anthony; De Micheli, Giovanni

    2012-01-01

    Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications.

  7. Immediate Return to Ambulation and Improved Functional Capacity for Rehabilitation in Complex Regional Pain Syndrome following Early Implantation of a Spinal Cord Stimulation System.

    PubMed

    Goff, Brandon Jesse; Naber, Jeremy Wingseng; McCallin, John Patrick; Lopez, Edward Michael; Guthmiller, Kevin Brant; Lautenschlager, Karl Alan; Lai, Tristan Toll; Hommer, Dean Harry; Marin, Gonzalez Raul

    2014-01-01

    Complex regional pain syndrome (CRPS) is a neuropathic pain condition that is characterized by vasomotor, sensory, sudomotor, and motor symptoms. Spinal cord stimulation (SCS) has been successfully utilized for the treatment of pain refractory to conventional therapies. We present a case of a previously highly functioning 54-year-old female who developed a rarely reported case of idiopathic CRPS of the right ankle which spontaneously occurred four months after an uncomplicated anterior cervical disc fusion. This condition resulted in severe pain and functional impairment that was unresponsive to pharmacological management. The patient's rehabilitation was severely stymied by her excruciating pain. However, with the initiation of spinal cord stimulation, her pain was adequately controlled allowing for progression to full unassisted ambulation, advancing functional capacity, and improving quality of life. This case report supports the concept that rapid progression to neuromodulation, rather than delays that occur due to attempts at serial sympathetic blocks, may better control symptoms leading allowing for a more meaningful recovery. PMID:25525522

  8. Immediate Return to Ambulation and Improved Functional Capacity for Rehabilitation in Complex Regional Pain Syndrome following Early Implantation of a Spinal Cord Stimulation System

    PubMed Central

    Goff, Brandon Jesse; Naber, Jeremy Wingseng; McCallin, John Patrick; Lopez, Edward Michael; Guthmiller, Kevin Brant; Lautenschlager, Karl Alan; Lai, Tristan Toll; Hommer, Dean Harry; Marin, Gonzalez Raul

    2014-01-01

    Complex regional pain syndrome (CRPS) is a neuropathic pain condition that is characterized by vasomotor, sensory, sudomotor, and motor symptoms. Spinal cord stimulation (SCS) has been successfully utilized for the treatment of pain refractory to conventional therapies. We present a case of a previously highly functioning 54-year-old female who developed a rarely reported case of idiopathic CRPS of the right ankle which spontaneously occurred four months after an uncomplicated anterior cervical disc fusion. This condition resulted in severe pain and functional impairment that was unresponsive to pharmacological management. The patient's rehabilitation was severely stymied by her excruciating pain. However, with the initiation of spinal cord stimulation, her pain was adequately controlled allowing for progression to full unassisted ambulation, advancing functional capacity, and improving quality of life. This case report supports the concept that rapid progression to neuromodulation, rather than delays that occur due to attempts at serial sympathetic blocks, may better control symptoms leading allowing for a more meaningful recovery. PMID:25525522

  9. Peripheral nerve stimulation: definition.

    PubMed

    Abejón, David; Pérez-Cajaraville, Juan

    2011-01-01

    Recently, there has been a tremendous evolution in the field of neurostimulation, both from the technological point of view and from development of the new and different indications. In some areas, such as peripheral nerve stimulation, there has been a boom in recent years due to the variations in the surgical technique and the improved results documented by in multiple published papers. All this makes imperative the need to classify and define the different types of stimulation that are used today. The confusion arises when attempting to describe peripheral nerve stimulation and subcutaneous stimulation. Peripheral nerve stimulation, in its pure definition, involves implanting a lead on a nerve, with the aim to produce paresthesia along the entire trajectory of the stimulated nerve.

  10. Electrical stimulation for the relief of pain.

    PubMed

    Miles, J

    1984-03-01

    Electrical stimulation can relieve some severe and otherwise persisting pains. At its best it can be associated with either a gradual reduction in the pain or an increased ability by the patient to control his suffering. It seems particularly appropriate for use in the field of benign persistent pain. Equipment design and materials, particularly for implantable circuits, are not perfect. Movement towards percutaneous implantation, obviating the need for open operation, seems progressively more popular. Any unit or group using this form of treatment, must be prepared to provide major technical facilities, both in the form of people and equipment in order to cater for the many purely technical problems that occur. A great deal of knowledge both neurophysiological and neurochemical seems to be accruing from the clinical use of electrical stimulation. We would do well to take advantage of this opportunity, in the hope that it might lead us to a better understanding of the functioning of the nervous system. This consideration remarkably parallels an observation made by John Hunter in his presentation to the Royal Society in 1773 (13) which anticipated the realisation of the part played by electricity in the function of nerves. Following his description of the extraordinary innervation of the electric organs of the Torpedo fish, he wrote: 'How far this may be connected with the power of the nerves in general, or how far it may lead to an explanation of their operations, time and future discoveries alone can fully determine.' PMID:6608312

  11. Beyond cochlear implants: awakening the deafened brain.

    PubMed

    Moore, David R; Shannon, Robert V

    2009-06-01

    Cochlear implants have provided hearing to more than 120,000 deaf people. Recent surgical developments include direct electrical stimulation of the brain, bilateral implants and implantation in children less than 1 year old. However, research is beginning to refocus on the role of the brain in providing benefits to implant users. The auditory system is able to use the highly impoverished input provided by implants to interpret speech, but this only works well in those who have developed language before their deafness or in those who receive their implant at a very young age. We discuss recent evidence suggesting that developing the ability of the brain to learn how to use an implant may be as important as further improvements of the implant technology. PMID:19471266

  12. IMPORTANCE OF COCHLEAR HEALTH FOR IMPLANT FUNCTION

    PubMed Central

    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.

    2014-01-01

    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. PMID:25261772

  13. Neuroprotection trek--the next generation: neuromodulation I. Techniques--deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation

    NASA Technical Reports Server (NTRS)

    Andrews, Russell J.

    2003-01-01

    Neuromodulation denotes controlled electrical stimulation of the central or peripheral nervous system. The three forms of neuromodulation described in this paper-deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation-were chosen primarily for their demonstrated or potential clinical usefulness. Deep brain stimulation is a completely implanted technique for improving movement disorders, such as Parkinson's disease, by very focal electrical stimulation of the brain-a technique that employs well-established hardware (electrode and pulse generator/battery). Vagus nerve stimulation is similar to deep brain stimulation in being well-established (for the treatment of refractory epilepsy), completely implanted, and having hardware that can be considered standard at the present time. Vagus nerve stimulation differs from deep brain stimulation, however, in that afferent stimulation of the vagus nerve results in diffuse effects on many regions throughout the brain. Although use of deep brain stimulation for applications beyond movement disorders will no doubt involve placing the stimulating electrode(s) in regions other than the thalamus, subthalamus, or globus pallidus, the use of vagus nerve stimulation for applications beyond epilepsy-for example, depression and eating disorders-is unlikely to require altering the hardware significantly (although stimulation protocols may differ). Transcranial magnetic stimulation is an example of an external or non-implanted, intermittent (at least given the current state of the hardware) stimulation technique, the clinical value of which for neuromodulation and neuroprotection remains to be determined.

  14. Implantable Microimagers

    PubMed Central

    Ng, David C.; Tokuda, Takashi; Shiosaka, Sadao; Tano, Yasuo; Ohta, Jun

    2008-01-01

    Implantable devices such as cardiac pacemakers, drug-delivery systems, and defibrillators have had a tremendous impact on the quality of live for many disabled people. To date, many devices have been developed for implantation into various parts of the human body. In this paper, we focus on devices implanted in the head. In particular, we describe the technologies necessary to create implantable microimagers. Design, fabrication, and implementation issues are discussed vis-à-vis two examples of implantable microimagers; the retinal prosthesis and in vivo neuro-microimager. Testing of these devices in animals verify the use of the microimagers in the implanted state. We believe that further advancement of these devices will lead to the development of a new method for medical and scientific applications.

  15. Implant Design in Cementless Hip Arthroplasty

    PubMed Central

    Kim, Jung Taek

    2016-01-01

    When performing cementless hip arthroplasty, it is critical to achieve firm primary mechanical stability followed by biological fixation. In order to achieve this, it is essential to fully understand characteristics of implant design. In this review, the authors review fixation principles for a variety of implants used for cementless hip replacement and considerations for making an optimal selection. PMID:27536647

  16. Cochlear implant simulator for surgical technique analysis

    NASA Astrophysics Data System (ADS)

    Turok, Rebecca L.; Labadie, Robert F.; Wanna, George B.; Dawant, Benoit M.; Noble, Jack H.

    2014-03-01

    Cochlear Implant (CI) surgery is a procedure in which an electrode array is inserted into the cochlea. The electrode array is used to stimulate auditory nerve fibers and restore hearing for people with severe to profound hearing loss. The primary goals when placing the electrode array are to fully insert the array into the cochlea while minimizing trauma to the cochlea. Studying the relationship between surgical outcome and various surgical techniques has been difficult since trauma and electrode placement are generally unknown without histology. Our group has created a CI placement simulator that combines an interactive 3D visualization environment with a haptic-feedback-enabled controller. Surgical techniques and patient anatomy can be varied between simulations so that outcomes can be studied under varied conditions. With this system, we envision that through numerous trials we will be able to statistically analyze how outcomes relate to surgical techniques. As a first test of this system, in this work, we have designed an experiment in which we compare the spatial distribution of forces imparted to the cochlea in the array insertion procedure when using two different but commonly used surgical techniques for cochlear access, called round window and cochleostomy access. Our results suggest that CIs implanted using round window access may cause less trauma to deeper intracochlear structures than cochleostomy techniques. This result is of interest because it challenges traditional thinking in the otological community but might offer an explanation for recent anecdotal evidence that suggests that round window access techniques lead to better outcomes.

  17. Toward Fully Synthetic Homogeneous β-Human Follicle-Stimulating Hormone (β-hFSH) with a Biantennary N-linked Dodecasaccharide. Synthesis of β-hFSH with Chitobiose Units at the Natural Linkage Sites

    PubMed Central

    Nagorny, Pavel; Fasching, Bernhard; Li, Xuechen; Chen, Gong; Aussedat, Baptiste; Danishefsky, Samuel J.

    2009-01-01

    A highly convergent synthesis of the sialic acid rich biantennary N-linked glycan found in human glycoprotein hormones, and its use in the synthesis of a fragment derived from the β-domain of human Follicle-Stimulating Hormone (hFSH) are described. The synthesis highlights the use of the Sinaÿ radical glycosidation protocol for the simultaneous installation of both biantennary side-chains of the dodecasaccharide as well as the use of glycal chemistry to construct the tetrasaccharide core in an efficient manner. The synthetic glycan was used to prepare the glycosylated 20–27aa domain of β-subunit of hFSH under a Lansbury aspartylation protocol. The proposed strategy for incorporating the prepared N-linked dodecasaccharide-containing 20–27aa domain into β-hFSH subunit was validated in the context of a model system providing, protected β-hFSH subunit functionalized with chitobiose at positions 7 and 24. PMID:19341309

  18. Histrelin Implant

    MedlinePlus

    ... response to histrelin implant. Your blood sugar and glycosylated hemoglobin (HbA1c) should be checked regularly.Ask your pharmacist any questions you have about histrelin implant.It is important for you to keep a written list of all of the prescription and ...

  19. Capacitive Feedthroughs for Medical Implants.

    PubMed

    Grob, Sven; Tass, Peter A; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging.

  20. Capacitive Feedthroughs for Medical Implants.

    PubMed

    Grob, Sven; Tass, Peter A; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging. PMID:27660602

  1. Capacitive Feedthroughs for Medical Implants

    PubMed Central

    Grob, Sven; Tass, Peter A.; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging. PMID:27660602

  2. Capacitive Feedthroughs for Medical Implants

    PubMed Central

    Grob, Sven; Tass, Peter A.; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging.

  3. 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…

  4. Cochlear implant

    MedlinePlus

    ... implant. These specialists may include: Audiologists Speech therapists Ear, nose, and throat doctors (otolaryngologists) This is a very important part of the process. You will need to work closely with your team of specialists to get ...

  5. Cochlear Implants

    MedlinePlus

    ... additional visits are needed for activating, adjusting, and programming the various electrodes that have been implanted. Also, ... to the center for checkups once the final programming is made to the speech processor. Both children ...

  6. The effect of enzymatically degradable IPN coatings on peri-implant bone formation and implant fixation.

    PubMed

    Ho, James E; Barber, Thomas A; Virdi, Amarjit S; Sumner, Dale R; Healy, Kevin E

    2007-06-01

    Short-term osseointegration of orthopedic implants is critical for the long-term stability of the implant-bone interface. To improve initial implant stability, one strategy under consideration involves the presentation of adhesion ligands on the implant surface to stimulate bone regeneration in the peri-implant region. To assess the relative effects of implant surface chemistry and topography on osseointegration within the rat femoral ablation implant model, a nonfouling, enzymatically degradable interpenetrating polymer network (edIPN) of poly(AAm-co-EG/AAc) amenable to presenting the cell signaling domain Arg-Gly-Asp (RGD), was developed. Moderate enhancement of peri-implant bone formation was found after 28 days using the edIPN without peptide modification (p = 0.032). However, no data supported a benefit of peptide modification, as bone-implant contact, normalized bone volume and normalized fixation strength was equivalent or poorer than dual acid-etched (DAE) treated implants after 28 days. Surface topography was determined to be the dominant factor in modulating osseointegration, as DAE implants produced equivalent roughness-normalized fixation strength versus previously reported data on plasma-sprayed hydroxyapatite/tricalcium phosphate-coated implants (Barber et al., J Biomed Mater Res A, forthcoming). An ideal osseointegrated implant will require optimization of all three aforementioned parameters, and may take the form of biomolecule delivery from thin degradable polymer networks. PMID:17212345

  7. Contraceptive implants.

    PubMed

    McDonald-Mosley, Raegan; Burke, Anne E

    2010-03-01

    Implantable contraception has been extensively used worldwide. Implants are one of the most effective and reversible methods of contraception available. These devices may be particularly appropriate for certain populations of women, including women who cannot use estrogen-containing contraception. Implants are safe for use by women with many chronic medical problems. The newest implant, Implanon (Organon International, Oss, The Netherlands), is the only device currently available in the United States and was approved in 2006. It is registered for 3 years of pregnancy prevention. Contraceptive implants have failure rates similar to tubal ligation, and yet they are readily reversible with a return to fertility within days of removal. Moreover, these contraceptive devices can be safely placed in the immediate postpartum period, ensuring good contraceptive coverage for women who may be at risk for an unintended pregnancy. Irregular bleeding is a common side effect for all progestin-only contraceptive implants. Preinsertion counseling should address possible side effects, and treatment may be offered to women who experience prolonged or frequent bleeding.

  8. Physical modification of polyetheretherketone for orthopedic implants

    NASA Astrophysics Data System (ADS)

    Du, Ya-Wei; Zhang, Li-Nan; Hou, Zeng-Tao; Ye, Xin; Gu, Hong-Sheng; Yan, Guo-Ping; Shang, Peng

    2014-12-01

    Polyetheretherketone (PEEK) is regarded as one of the most potential candidates for replacing current implant applications. To obtain good bone-implant interfaces, many modification methods have been developed to enable PEEK and PEEK-based composites from bio-inert to bioactive. Among them, physical methods have aroused significant attention and been widely used to modify PEEK for orthopedic implants. This review summarizes current physical modification techniques of PEEK for orthopedic applications, which include composite strategies, surface coating methods and irradiation treatments. The positive consequences of those modification methods will encourage continuing investigations and stimulate the wide range of applications of PEEK-based implants in orthopedics.

  9. A new approach towards a minimal invasive retina implant

    NASA Astrophysics Data System (ADS)

    Gerding, H.

    2007-03-01

    The possibility of using retina implants ('retinal prostheses') for the restoration of basic orientation in blind patients suffering from distal retinal diseases is presently under investigation by at least 18 independent project groups worldwide. It is a common feature of all implants to bypass degenerated retinal layers and to transfer visual information into the retinal network either by direct electrical stimulation or by neurotransmitter release. Contemporary implant designs are differing in the position of stimulating electrodes (epiretinal, subretinal, external) and the anatomical arrangement of implant components (intraocular, extraocular). The latter is of high relevance with regard to possible implant-tissue interactions and biological reactions. During the last few years new types of implants appeared that reduce intraocular components which are now deposited on the outer scleral surface or even in extraorbital position. The extreme of this trend are completely extraocular implants with transchoroidal or extraocular stimulation of the retina. The new type of implant presented in this paper combines the principle of direct retinal stimulation and minimal invasive implantation in a way that stimulating electrodes are the only implant component penetrating the eye via sclera, choroid and retinal pigment epithelium. All other device elements are positioned in extraocular position. The new concept necessitates a paradigmatic change about surgical handling of the choroid and multiple penetrations of the eye. Successful data about this type of retinal prosthesis are already available from long-term observation in non-human primates.

  10. In Vivo Validation of Custom-Designed Silicon-Based Microelectrode Arrays for Long-Term Neural Recording and Stimulation

    PubMed Central

    Manoonkitiwongsa, Panya S.; Wang, Cindy X.; McCreery, Douglas B.

    2012-01-01

    We developed and validated silicon-based neural probes for neural stimulating and recording in long-term implantation in the brain. The probes combine the deep reactive ion etching process and mechanical shaping of their tip region, yielding a mechanically sturdy shank with a sharpened tip to reduce insertion force into the brain and spinal cord, particularly, with multiple shanks in the same array. The arrays’ insertion forces have been quantified in vitro. Five consecutive chronically-implanted devices were fully functional from 3 to 18 months. The microelectrode sites were electroplated with iridium oxide, and the charge injection capacity measurements were performed both in vitro and after implantation in the adult feline brain. The functionality of the chronic array was validated by stimulating in the cochlear nucleus and recording the evoked neuronal activity in the central nucleus of the inferior colliculus. The arrays’ recording quality has also been quantified in vivo with neuronal spike activity recorded up to 566 days after implantation. Histopathology evaluation of neurons and astrocytes using immunohistochemical stains indicated minimal alterations of tissue architecture after chronic implantation. PMID:22020666

  11. Positron Emission Tomography in Cochlear Implant and Auditory Brainstem Implant Recipients.

    ERIC Educational Resources Information Center

    Miyamoto, Richard T.; Wong, Donald

    2001-01-01

    Positron emission tomography imaging was used to evaluate the brain's response to auditory stimulation, including speech, in deaf adults (five with cochlear implants and one with an auditory brainstem implant). Functional speech processing was associated with activation in areas classically associated with speech processing. (Contains five…

  12. Human Tissue Stimulator

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Neurodyne Corporation Human Tissue Stimulator (HTS) is a totally implantable system used for treatment of chronic pain and involuntary motion disorders by electrical stimulation. It was developed by Pacesetter Systems, Inc. in cooperation with the Applied Physics Laboratory. HTS incorporates a nickel cadmium battery, telemetry and command systems technologies of the same type as those used in NASA's Small Astronomy Satellite-3 in microminiature proportions so that the implantable element is the size of a deck of cards. The stimulator includes a rechargeable battery, an antenna and electronics to receive and process commands and to report on its own condition via telemetry, a wireless process wherein instrument data is converted to electrical signals and sent to a receiver where signals are presented as usable information. The HTS is targeted to nerve centers or to particular areas of the brain to provide relief from intractable pain or arrest involuntary motion. The nickel cadmium battery can be recharged through the skin. The first two HTS units were implanted last year and have been successful. Extensive testing is required before HTS can be made available for general use.

  13. Retinal implants: a systematic review.

    PubMed

    Chuang, Alice T; Margo, Curtis E; Greenberg, Paul B

    2014-07-01

    Retinal implants present an innovative way of restoring sight in degenerative retinal diseases. Previous reviews of research progress were written by groups developing their own devices. This systematic review objectively compares selected models by examining publications describing five representative retinal prostheses: Argus II, Boston Retinal Implant Project, Epi-Ret 3, Intelligent Medical Implants (IMI) and Alpha-IMS (Retina Implant AG). Publications were analysed using three criteria for interim success: clinical availability, vision restoration potential and long-term biocompatibility. Clinical availability: Argus II is the only device with FDA approval. Argus II and Alpha-IMS have both received the European CE Marking. All others are in clinical trials, except the Boston Retinal Implant, which is in animal studies. Vision restoration: resolution theoretically correlates with electrode number. Among devices with external cameras, the Boston Retinal Implant leads with 100 electrodes, followed by Argus II with 60 electrodes and visual acuity of 20/1262. Instead of an external camera, Alpha-IMS uses a photodiode system dependent on natural eye movements and can deliver visual acuity up to 20/546. Long-term compatibility: IMI offers iterative learning; Epi-Ret 3 is a fully intraocular device; Alpha-IMS uses intraocular photosensitive elements. Merging the results of these three criteria, Alpha-IMS is the most likely to achieve long-term success decades later, beyond current clinical availability. PMID:24403565

  14. Orbital implants: potential new directions.

    PubMed

    Hicks, Celia R; Morrison, David; Lou, Xia; Crawford, Geoffrey J; Gadjatsy, Adam; Constable, Ian J

    2006-11-01

    This article reviews orbital implants used to replace an eye after enucleation or evisceration. Advantages of implant placement are described, with discussion of implant and wrap material, and design features that affect clinical outcomes. Implants may be porous or nonporous, pegged for linkage with a cosmetic shell or unpegged, and may be wrapped with a covering material or tissue or unwrapped. Device shape, volume and material qualities affect tissue tolerance and the risk of exposure or extrusion. Limitations of currently available devices are discussed, with factors affecting surgeon and patient choice. Ideally, a device should be easy to insert, avoid the need for wrapping or adjunctive tissues, be light, biointegratable, comfortable after implantation and provide satisfactory orbital volume replacement, movement and cosmesis without requiring further surgery or pegging. This review briefly discusses developments in implant design and aspects of design that affect function, but is not a detailed clinical review; rather, it aims to stimulate thought on optimal design and discusses recent developments. Novel technology in the form of a prototype device with a soft, biointegratable anterior surface is described as an example of newer approaches.

  15. [Neurotology and cochlear implants].

    PubMed

    Merchán, Miguel A

    2015-05-01

    In this review we analyse cochlear implantation in terms of the fundamental aspects of the functioning of the auditory system. Concepts concerning neuronal plasticity applied to electrical stimulation in perinatal and adult deep hypoacusis are reviewed, and the latest scientific bases that justify early implantation following screening for congenital deafness are discussed. Finally, this review aims to serve as an example of the importance of fostering the sub-specialty of neurotology in our milieu, with the aim of bridging some of the gaps between specialties and thus improving both the knowledge in the field of research on auditory pathologies and in the screening of patients. The objectives of this review, targeted above all towards specialists in the field of otorhinolaryngology, are to analyse some significant neurological foundations in order to reach a better understanding of the clinical events that condition the indications and the rehabilitation of patients with cochlear implants, as well as to use this means to foster the growth of the sub-specialty of neurotology.

  16. Electrical stimulation for the relief of pain.

    PubMed Central

    Miles, J.

    1984-01-01

    Electrical stimulation can relieve some severe and otherwise persisting pains. At its best it can be associated with either a gradual reduction in the pain or an increased ability by the patient to control his suffering. It seems particularly appropriate for use in the field of benign persistent pain. Equipment design and materials, particularly for implantable circuits, are not perfect. Movement towards percutaneous implantation, obviating the need for open operation, seems progressively more popular. Any unit or group using this form of treatment, must be prepared to provide major technical facilities, both in the form of people and equipment in order to cater for the many purely technical problems that occur. A great deal of knowledge both neurophysiological and neurochemical seems to be accruing from the clinical use of electrical stimulation. We would do well to take advantage of this opportunity, in the hope that it might lead us to a better understanding of the functioning of the nervous system. This consideration remarkably parallels an observation made by John Hunter in his presentation to the Royal Society in 1773 (13) which anticipated the realisation of the part played by electricity in the function of nerves. Following his description of the extraordinary innervation of the electric organs of the Torpedo fish, he wrote: 'How far this may be connected with the power of the nerves in general, or how far it may lead to an explanation of their operations, time and future discoveries alone can fully determine.' Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:6608312

  17. A fully-integrated high-compliance voltage SoC for epi-retinal and neural prostheses.

    PubMed

    Lo, Yi-Kai; Chen, Kuanfu; Gad, Parag; Liu, Wentai

    2013-12-01

    This paper presents a fully functionally integrated 1024-channel mixed-mode and mixed-voltage system-on-a-chip (SoC) for epi-retinal and neural prostheses. Taking an AC input, an integrated power telemetry circuits is capable of generating multiple DC voltages with a voltage conversion efficiency of 83% at a load of 100 mW without external diodes or separate power integrated circuits, reducing the form factor of the prosthetic device. A wireless DPSK receiver with a novel noise reduction scheme supports a data rate of 2 Mb/s at a bit-error-rate of 2 ×10⁻⁷. The 1024-channel stimulator array meets an output compliance voltage of ±10 V and provides flexible stimulation waveforms. Through chip-clustering, the stimulator array can be further expanded to 4096 channels. This SoC is designed and fabricated in TSMC 0.18 μm high-voltage 32 V CMOS process and occupies a chip area of 5.7 mm × 6.6 mm. Using this SoC, a retinal implant bench-top test system is set up with real-time visual verification. In-vitro experiment conducted in artificial vitreous humor is designed and set-up to investigate stimulation waveforms for better visual resolution. In our in-vivo experiment, a hind-limb paralyzed rat with spinal cord transection and implanted chronic epidural electrodes has been shown to regain stepping and standing abilities using stimulus provided by the SoC. PMID:24473541

  18. Cochlear Implants

    MedlinePlus

    ... outside of the body, behind the ear. A second part is surgically placed under the skin. An implant does not restore normal hearing. It can help a person understand speech. Children and adults can benefit from them. National Institute on Deafness and Other Communication Disorders

  19. Facial implants.

    PubMed

    Arcuri, M R; Rubenstein, J T

    1998-01-01

    The application of endosseous dental implants for the retention and stabilization of extraoral prostheses and hearing aids has been shown to be effective functionally and aesthetically. Implants have reduced the need for adhesive use, simplifying cleaning procedures and thus extending the life of the prosthesis. Implant-retained prostheses have provided patients the opportunity to participate in routine activities such as work, shopping, swimming, and jogging with less fear of losing their prosthesis. The implants' impact on patients has resulted in their ability to function in society with confidence that their defects will be less noticeable and their ability to respond to the environment enhanced. The culmination of these effects have without doubt improved the overall quality of life for patients. As with any new technology, its application will encounter unanticipated problems and some limitations in use. As the art and science of this technique evolve, however, it is anticipated that it will result in the ability to provide improved health care for patients.

  20. A linearized current stimulator for deep brain stimulation.

    PubMed

    Shen, Ding-Lan; Chu, Yu-Jung

    2010-01-01

    This paper develops the front end of the stimulator which is applied in the implantable deep brain stimulation (DBS) for the therapy of Parkinson's disease. This stimulator adopts the low power switched-capacitor DAC accompanying with voltage-to-current transconductance amplifiers to obtain the adjustable output currents. The proposed distortion cancellation technique improves the linearity of the current stimulator. Multiple transconductance amplifiers sharing a single DAC save the circuit area. The biphasic stimulation waveform is generated from the bridge switching technique and the programmable pulse. This stimulation circuit provides the 0 approximately 165 microA current for a typical loading of 10 kΩ, 8 approximately 120 micros pulse width, and 126 approximately 244 Hz frequencies with a 0.35 microm CMOS technology at 3.3 V supply voltage. PMID:21096724

  1. Testing fully depleted CCD

    NASA Astrophysics Data System (ADS)

    Casas, Ricard; Cardiel-Sas, Laia; Castander, Francisco J.; Jiménez, Jorge; de Vicente, Juan

    2014-08-01

    The focal plane of the PAU camera is composed of eighteen 2K x 4K CCDs. These devices, plus four spares, were provided by the Japanese company Hamamatsu Photonics K.K. with type no. S10892-04(X). These detectors are 200 μm thick fully depleted and back illuminated with an n-type silicon base. They have been built with a specific coating to be sensitive in the range from 300 to 1,100 nm. Their square pixel size is 15 μm. The read-out system consists of a Monsoon controller (NOAO) and the panVIEW software package. The deafualt CCD read-out speed is 133 kpixel/s. This is the value used in the calibration process. Before installing these devices in the camera focal plane, they were characterized using the facilities of the ICE (CSIC- IEEC) and IFAE in the UAB Campus in Bellaterra (Barcelona, Catalonia, Spain). The basic tests performed for all CCDs were to obtain the photon transfer curve (PTC), the charge transfer efficiency (CTE) using X-rays and the EPER method, linearity, read-out noise, dark current, persistence, cosmetics and quantum efficiency. The X-rays images were also used for the analysis of the charge diffusion for different substrate voltages (VSUB). Regarding the cosmetics, and in addition to white and dark pixels, some patterns were also found. The first one, which appears in all devices, is the presence of half circles in the external edges. The origin of this pattern can be related to the assembly process. A second one appears in the dark images, and shows bright arcs connecting corners along the vertical axis of the CCD. This feature appears in all CCDs exactly in the same position so our guess is that the pattern is due to electrical fields. Finally, and just in two devices, there is a spot with wavelength dependence whose origin could be the result of a defectous coating process.

  2. Biocompatible implants and methods of making and attaching the same

    DOEpatents

    Rowley, Adrian P; Laude, Lucien D; Humayun, Mark S; Weiland, James D; Lotfi, Atoosa; Markland, Jr., Francis S

    2014-10-07

    The invention provides a biocompatible silicone implant that can be securely affixed to living tissue through interaction with integral membrane proteins (integrins). A silicone article containing a laser-activated surface is utilized to make the implant. One example is an implantable prosthesis to treat blindness caused by outer retinal degenerative diseases. The device bypasses damaged photoreceptors and electrically stimulates the undamaged neurons of the retina. Electrical stimulation is achieved using a silicone microelectrode array (MEA). A safe, protein adhesive is used in attaching the MEA to the retinal surface and assist in alleviating focal pressure effects. Methods of making and attaching such implants are also provided.

  3. A cochlear implant fabricated using a bulk silicon-surface micromachining process

    NASA Astrophysics Data System (ADS)

    Bell, Tracy Elizabeth

    1999-11-01

    This dissertation presents the design and fabrication of two generations of a silicon microelectrode array for use in a cochlear implant. A cochlear implant is a device that is inserted into the inner ear and uses electrical stimulation to provide sound sensations to the profoundly deaf. The first-generation silicon cochlear implant is a passive device fabricated using silicon microprobe technology developed at the University of Michigan. It contains twenty-two iridium oxide (IrO) stimulating sites that are 250 mum in diameter and spaced at 750 mum intervals. In-vivo recordings were made in guinea pig auditory cortex in response to electrical stimulation with this device, verifying its ability to electrically evoke an auditory response. Auditory thresholds as low as 78 muA were recorded. The second-generation implant is a thirty-two site, four-channel device with on-chip CMOS site-selection circuitry and integrated position sensing. It was fabricated using a novel bulk silicon surface micromachining process which was developed as a part of this dissertation work. While the use of semiconductor technology offers many advantages in fabricating cochlear implants over the methods currently used, it was felt that even further advantages could be gained by developing a new micromachining process which would allow circuitry to be distributed along the full length of the cochlear implant substrate. The new process uses electropolishing of an n+ bulk silicon sacrificial layer to undercut and release n- epitaxial silicon structures from the wafer. An extremely abrupt etch-stop between the n+ and n- silicon is obtained, with no electropolishing taking place in the n-type silicon that is doped lower than 1 x 1017 cm-3 in concentration. Lateral electropolishing rates of up to 50 mum/min were measured using this technique, allowing one millimeter-wide structures to be fully undercut in as little as 10 minutes. The new micromachining process was integrated with a standard p

  4. This Neural Implant is designed to be implanted in the Human Central and Nervous System

    SciTech Connect

    2013-10-29

    A new class of neural implants being developed at the Livermore Lab are the first clinical quality devices capable of two-way conversations with the human nervous systems. Unlike existing interfaces that only sense or only stimulate, these devices are capable of stimulating and sensing using both electric and chemical signals.

  5. Language acquisition after cochlear implantation of congenitally deaf children: Effect of age at implantation

    NASA Astrophysics Data System (ADS)

    Svirsky, Mario; Holt, Rachael

    2005-04-01

    Evidence shows that early implantation of congenitally deaf children is beneficial. However, infants as young as 6 months of age have started to receive cochlear implants (CIs) in the USA. Such early implantation may be associated with higher risks, including anesthetic risk as well as the increased possibility of a false positive in the diagnosis of profound deafness. On the other hand, delaying implantation may be associated with the risk of missing windows of opportunity or sensitive periods for the development of communication skills. In this study, speech perception and language skills in children who received CIs in the first, second, third, or fourth year of life were compared. Participants were tested at regular 6-month intervals after implantation. The effects of several potential confounds were considered. In general, children implanted earlier outperformed those implanted later, with one exception: infants implanted at 6-12 months showed similar outcomes to children implanted at 12-24 months, at least through 2 to 2-1/2 years of age. This preliminary result may be associated with the difficulty of choosing appropriate stimulation parameters for infants, and its potential influence on the quality of the stimulation patterns delivered by the CI.

  6. Improved polyimide thin-film electrodes for neural implants.

    PubMed

    Ordonez, Juan S; Boehler, Christian; Schuettler, Martin; Stieglitz, Thomas

    2012-01-01

    Thin-film electrode arrays for neural implants are necessary when large integration densities of stimulating or recording channels are required. However, delamination of the metallic layers from the polymer substrate leads to early failure of the device. Based on new adhesion studies of polyimide to SiC and diamond-like carbon (DLC) the authors successfully fabricated a 232-channel electrode array for retinal stimulation with improved adhesion. Layers of SiC and DLC were integrated into the fabrication procedure of polyimide-platinum (Pt) arrays to create fully coated metal wires, which adhere to the polyimide substrate even after 1 year of accelerated aging in saline solution. Studies on the inter-diffusion of Pt and SiC were conducted to establish an optimal thickness for a gold core of the platinum tracks, which is used for reducing the electrical track resistance. Furthermore, the electrochemical behaviour of the stimulating contacts coated with IrOx were studied in a long-term pulse tests over millions of pulses showing no deterioration of the coating.

  7. Improved polyimide thin-film electrodes for neural implants.

    PubMed

    Ordonez, Juan S; Boehler, Christian; Schuettler, Martin; Stieglitz, Thomas

    2012-01-01

    Thin-film electrode arrays for neural implants are necessary when large integration densities of stimulating or recording channels are required. However, delamination of the metallic layers from the polymer substrate leads to early failure of the device. Based on new adhesion studies of polyimide to SiC and diamond-like carbon (DLC) the authors successfully fabricated a 232-channel electrode array for retinal stimulation with improved adhesion. Layers of SiC and DLC were integrated into the fabrication procedure of polyimide-platinum (Pt) arrays to create fully coated metal wires, which adhere to the polyimide substrate even after 1 year of accelerated aging in saline solution. Studies on the inter-diffusion of Pt and SiC were conducted to establish an optimal thickness for a gold core of the platinum tracks, which is used for reducing the electrical track resistance. Furthermore, the electrochemical behaviour of the stimulating contacts coated with IrOx were studied in a long-term pulse tests over millions of pulses showing no deterioration of the coating. PMID:23367084

  8. Digital photoelastic analysis applied to implant dentistry

    NASA Astrophysics Data System (ADS)

    Ramesh, K.; Hariprasad, M. P.; Bhuvanewari, S.

    2016-12-01

    Development of improved designs of implant systems in dentistry have necessitated the study of stress fields in the implant regions of the mandible/maxilla for better understanding of the biomechanics involved. Photoelasticity has been used for various studies related to dental implants in view of whole field visualization of maximum shear stress in the form of isochromatic contours. The potential of digital photoelasticity has not been fully exploited in the field of implant dentistry. In this paper, the fringe field in the vicinity of the connected implants (All-On-Four® concept) is analyzed using recent advances in digital photoelasticity. Initially, a novel 3-D photoelastic model making procedure, to closely mimic all the anatomical features of the human mandible is proposed. By choosing appropriate orientation of the model with respect to the light path, the essential region of interest were sought to be analysed while keeping the model under live loading conditions. Need for a sophisticated software module to carefully identify the model domain has been brought out. For data extraction, five-step method is used and isochromatics are evaluated by twelve fringe photoelasticity. In addition to the isochromatic fringe field, whole field isoclinic data is also obtained for the first time in implant dentistry, which could throw important information in improving the structural stability of the implant systems. Analysis is carried out for the implant in the molar as well as the incisor region. In addition, the interaction effects of loaded molar implant on the incisor area are also studied.

  9. Carbon Fiber Biocompatibility for Implants

    PubMed Central

    Petersen, Richard

    2016-01-01

    Carbon fibers have multiple potential advantages in developing high-strength biomaterials with a density close to bone for better stress transfer and electrical properties that enhance tissue formation. As a breakthrough example in biomaterials, a 1.5 mm diameter bisphenol-epoxy/carbon-fiber-reinforced composite rod was compared for two weeks in a rat tibia model with a similar 1.5 mm diameter titanium-6-4 alloy screw manufactured to retain bone implants. Results showed that carbon-fiber-reinforced composite stimulated osseointegration inside the tibia bone marrow measured as percent bone area (PBA) to a great extent when compared to the titanium-6-4 alloy at statistically significant levels. PBA increased significantly with the carbon-fiber composite over the titanium-6-4 alloy for distances from the implant surfaces of 0.1 mm at 77.7% vs. 19.3% (p < 10−8) and 0.8 mm at 41.6% vs. 19.5% (p < 10−4), respectively. The review focuses on carbon fiber properties that increased PBA for enhanced implant osseointegration. Carbon fibers acting as polymer coated electrically conducting micro-biocircuits appear to provide a biocompatible semi-antioxidant property to remove damaging electron free radicals from the surrounding implant surface. Further, carbon fibers by removing excess electrons produced from the cellular mitochondrial electron transport chain during periods of hypoxia perhaps stimulate bone cell recruitment by free-radical chemotactic influences. In addition, well-studied bioorganic cell actin carbon fiber growth would appear to interface in close contact with the carbon-fiber-reinforced composite implant. Resulting subsequent actin carbon fiber/implant carbon fiber contacts then could help in discharging the electron biological overloads through electrochemical gradients to lower negative charges and lower concentration. PMID:26966555

  10. Applier tool for intradural spinal cord implants.

    PubMed

    Oya, H; Reddy, C G; Dahdaleh, N S; Wilson, S; Howard, M A; Jeffery, N D; Utz, M; Gillies, G T

    2012-04-01

    We have designed, built and tested a novel device for placing intradural neurmodulator implants directly on the pial surface of the spinal cord. This applier tool is designed for ergonomic handling of delicate electro-mechanical devices such as the Iowa-Patch™ spinal cord stimulator implant, which is aimed at overcoming certain shortcomings in the performance of standard epidural stimulator devices. The applier is approximately 14 cm long, 6 mm in diameter, made of stainless steel components, and has simple and reliable mechanisms for the attachment and release of the implant from it. We describe the design of the device, details of its construction, and its performance during in vivo testing of somatosensory evoked potentials in an ovine model of intradural spinal cord stimulation. PMID:22339111

  11. Short Implants: New Horizon in Implant Dentistry

    PubMed Central

    Gulati, Manisha; Garg, Meenu; Pathak, Chetan

    2016-01-01

    The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration. PMID:27790598

  12. Dental implant design--effect on bone remodeling.

    PubMed

    Pilliar, R M; Deporter, D A; Watson, P A; Valiquette, N

    1991-04-01

    Bone remodeling around three different endosseous dental implant designs placed in dog mandibles was studied using radiography during lengthy periods of function and by histology after animal sacrifice. The three designs investigated were (a) threaded (c.p. titanium), (b) fully porous-coated (titanium alloy), and (c) partially porous-coated (titanium alloy). The implants were kept in function for either 32 weeks (fully porous-coated) or 73 to 77 weeks (partially porous-coated and threaded). The studies indicated that some crestal bone loss occurred for both the threaded and partially porous-coated implants while no significant bone loss was seen with fully porous-coated implants in the absence of plaque-associated infection. It is suggested that these observed differences are a result of the different stress states that develop in bone surrounding the three designs underlying the importance of implant design on bone remodeling.

  13. Randomized controlled clinical trial of 2 types of hydroxyapatite-coated implants on moderate periodontitis patients

    PubMed Central

    2016-01-01

    Purpose The aim of this study was to compare and analyze the peri-implant tissue conditions and prospective clinical outcomes associated with 2 types of hydroxyapatite (HA)-coated implants: (1) fully HA-coated implants and (2) partially HA-coated implants with resorbable blast medium on the coronal portion of the threads. Methods Forty-four partially edentulous patients were randomly assigned to undergo the placement of 62 HA-coated implants, and were classified as the control group (partially HA-coated, n=30) and the test group (fully HA-coated, n=32). All patients had chronic periodontitis with moderate crestal bone loss around the edentulous area. The stability and clinical outcomes of the implants were evaluated using the primary and secondary implant stability quotient (ISQ), as well as radiographic, mobility, and peri-implant soft tissue assessments around the implants. The Wilcoxon signed-rank test and the Mann-Whitney test were used to evaluate differences between and within the 2 groups, with P values <0.05 considered to indicate statistical significance. Results The fully HA-coated implants displayed good retention of crestal bone, and insignificant differences were found in annual marginal bone loss between the 2 types of HA-coated implants (P>0.05). No significant differences were found in the survival rate (group I, 100%; group II, 100%) or the success rate (group I, 93.3%; group II, 93.8%). The fully HA-coated implants also did not significantly increase the risk of peri-implantitis (P>0.05). Conclusions The fully HA-coated implants did not lead to an increased risk of peri-implantitis and showed good retention of the crestal bone, as well as good survival and success rates. Our study suggests that fully HA-coated implants could become a reliable treatment alternative for edentulous posterior sites and are capable of providing good retention of the crestal bone. PMID:27800216

  14. Brainjacking: Implant Security Issues in Invasive Neuromodulation.

    PubMed

    Pycroft, Laurie; Boccard, Sandra G; Owen, Sarah L F; Stein, John F; Fitzgerald, James J; Green, Alexander L; Aziz, Tipu Z

    2016-08-01

    The security of medical devices is critical to good patient care, especially when the devices are implanted. In light of recent developments in information security, there is reason to be concerned that medical implants are vulnerable to attack. The ability of attackers to exert malicious control over brain implants ("brainjacking") has unique challenges that we address in this review, with particular focus on deep brain stimulation implants. To illustrate the potential severity of this risk, we identify several mechanisms through which attackers could manipulate patients if unauthorized access to an implant can be achieved. These include blind attacks in which the attacker requires no patient-specific knowledge and targeted attacks that require patient-specific information. Blind attacks include cessation of stimulation, draining implant batteries, inducing tissue damage, and information theft. Targeted attacks include impairment of motor function, alteration of impulse control, modification of emotions or affect, induction of pain, and modulation of the reward system. We also discuss the limitations inherent in designing implants and the trade-offs that must be made to balance device security with battery life and practicality. We conclude that researchers, clinicians, manufacturers, and regulatory bodies should cooperate to minimize the risk posed by brainjacking. PMID:27184896

  15. Brainjacking: Implant Security Issues in Invasive Neuromodulation.

    PubMed

    Pycroft, Laurie; Boccard, Sandra G; Owen, Sarah L F; Stein, John F; Fitzgerald, James J; Green, Alexander L; Aziz, Tipu Z

    2016-08-01

    The security of medical devices is critical to good patient care, especially when the devices are implanted. In light of recent developments in information security, there is reason to be concerned that medical implants are vulnerable to attack. The ability of attackers to exert malicious control over brain implants ("brainjacking") has unique challenges that we address in this review, with particular focus on deep brain stimulation implants. To illustrate the potential severity of this risk, we identify several mechanisms through which attackers could manipulate patients if unauthorized access to an implant can be achieved. These include blind attacks in which the attacker requires no patient-specific knowledge and targeted attacks that require patient-specific information. Blind attacks include cessation of stimulation, draining implant batteries, inducing tissue damage, and information theft. Targeted attacks include impairment of motor function, alteration of impulse control, modification of emotions or affect, induction of pain, and modulation of the reward system. We also discuss the limitations inherent in designing implants and the trade-offs that must be made to balance device security with battery life and practicality. We conclude that researchers, clinicians, manufacturers, and regulatory bodies should cooperate to minimize the risk posed by brainjacking.

  16. 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…

  17. Outcomes from Clarion implantation in India.

    PubMed

    Desa Souza, Sandra G; D'Souza, Dillon; Kochure, Jaya; D'Souza, Natasha

    2004-01-01

    We evaluated the results of the use of Clarion (Advanced Bionics, USA) implants in 30 Indian patients. Cases included in the study were prelingual and postlingual patients in whom the cochlea was normal and prelingual patients in whom the cochlea had a Mondini defect or was ossified. We found that multiple speech strategies available with the Clarion implant were a distinct advantage. The postlingual patients fared better with speech discrimination in noise using the high-resolution strategy, and young prelingual patients developed hearing and speech faster using simultaneous analog stimulation and multiple pulsatile stimulation strategies. Moreover, in Mondini cases, all electrodes could be inserted using the enhanced bipolar device.

  18. Implantation and testing of subretinal film electrodes in domestic pigs.

    PubMed

    Schanze, Thomas; Sachs, Helmut G; Wiesenack, Christoph; Brunner, Ursula; Sailer, Heiko

    2006-02-01

    By definition, an electronic subretinal visual prosthesis requires the implantation of stimulation electrodes in the subretinal space of the eye. Polyimide film electrodes with flat contacts were implanted subretinally and used for electrical stimulation in acute experiments in anaesthetised domestic pigs. In two pigs, the film electrode was inserted through a sclerostomy into the vitreous cavity and, subsequently, via a retinotomy into the subretinal space around the posterior pole (ab interno approach). In three other pigs the sclera and pigment epithelium were opened for combined ab interno and transscleral positioning of the subretinal electrode. In all cases, perfluorocarbon liquid (PFCL) was used to establish a close contact between the film electrode and the outer retina. After cranial preparations of three pigs for epidural recording of visual cortex responses, retinal stimulation was performed in one pig with a film electrode implanted ab interno and in two pigs with film electrodes implanted by the ab interno and transscleral procedure. The five subretinal implantations were carried out successfully and each polyimide film electrode tip was positioned beneath the outer retina of the posterior pole. The retina was attached to the stimulation electrode in all cases. Epidural cortical responses to light and electrical stimulation were recorded in three experiments. Initial cortical responses to Ganzfeld light and to electrical stimuli occurred about 40 and 20 ms, respectively, after stimulation onset. The stimulation threshold was approximately 100 microA and, like the cortical response amplitudes, depended both on the correspondence between retinal stimulation and cortical recording sites and on the number of stimulation electrodes used simultaneously. Our results in a domestic pig model demonstrate that polyimide film electrodes can be implanted subretinally and tested by recording cortical responses to electrical stimulation. These findings suggest that

  19. Programming, Care, and Troubleshooting of Cochlear Implants for Children.

    ERIC Educational Resources Information Center

    Hedley-Williams, Andrea J.; Sladen, Douglas P.; Tharpe, Anne Marie

    2003-01-01

    This article provides an overview of current cochlear implant technology, programming strategies, troubleshooting, and care techniques. It considers: device components, initial stimulation, speech coding strategies, use and care, troubleshooting, and the classroom environment. (Contains references.) (DB)

  20. The Vestibular Implant: Quo Vadis?

    PubMed Central

    van de Berg, Raymond; Guinand, Nils; Stokroos, Robert J.; Guyot, Jean-Philippe; Kingma, Herman

    2011-01-01

    Objective: To assess the progress of the development of the vestibular implant (VI) and its feasibility short-term. Data sources: A search was performed in Pubmed, Medline, and Embase. Key words used were “vestibular prosth*” and “VI.” The only search limit was language: English or Dutch. Additional sources were medical books, conference lectures and our personal experience with per-operative vestibular stimulation in patients selected for cochlear implantation. Study selection: All studies about the VI and related topics were included and evaluated by two reviewers. No study was excluded since every study investigated different aspects of the VI. Data extraction and synthesis: Data was extracted by the first author from selected reports, supplemented by additional information, medical books conference lectures. Since each study had its own point of interest with its own outcomes, it was not possible to compare data of different studies. Conclusion: To use a basic VI in humans seems feasible in the very near future. Investigations show that electric stimulation of the canal nerves induces a nystagmus which corresponds to the plane of the canal which is innervated by the stimulated nerve branch. The brain is able to adapt to a higher baseline stimulation, while still reacting on a dynamic component. The best response will be achieved by a combination of the optimal stimulus (stimulus profile, stimulus location, precompensation), complemented by central vestibular adaptation. The degree of response will probably vary between individuals, depending on pathology and their ability to adapt. PMID:21991260

  1. Music perception with cochlear implants: a review.

    PubMed

    McDermott, Hugh J

    2004-01-01

    The acceptance of cochlear implantation as an effective and safe treatment for deafness has increased steadily over the past quarter century. The earliest devices were the first implanted prostheses found to be successful in compensating partially for lost sensory function by direct electrical stimulation of nerves. Initially, the main intention was to provide limited auditory sensations to people with profound or total sensorineural hearing impairment in both ears. Although the first cochlear implants aimed to provide patients with little more than awareness of environmental sounds and some cues to assist visual speech-reading, the technology has advanced rapidly. Currently, most people with modern cochlear implant systems can understand speech using the device alone, at least in favorable listening conditions. In recent years, an increasing research effort has been directed towards implant users' perception of nonspeech sounds, especially music. This paper reviews that research, discusses the published experimental results in terms of both psychophysical observations and device function, and concludes with some practical suggestions about how perception of music might be enhanced for implant recipients in the future. The most significant findings of past research are: (1) On average, implant users perceive rhythm about as well as listeners with normal hearing; (2) Even with technically sophisticated multiple-channel sound processors, recognition of melodies, especially without rhythmic or verbal cues, is poor, with performance at little better than chance levels for many implant users; (3) Perception of timbre, which is usually evaluated by experimental procedures that require subjects to identify musical instrument sounds, is generally unsatisfactory; (4) Implant users tend to rate the quality of musical sounds as less pleasant than listeners with normal hearing; (5) Auditory training programs that have been devised specifically to provide implant users with

  2. Fully automatic telemetry data processor

    NASA Technical Reports Server (NTRS)

    Cox, F. B.; Keipert, F. A.; Lee, R. C.

    1968-01-01

    Satellite Telemetry Automatic Reduction System /STARS 2/, a fully automatic computer-controlled telemetry data processor, maximizes data recovery, reduces turnaround time, increases flexibility, and improves operational efficiency. The system incorporates a CDC 3200 computer as its central element.

  3. Cerebellar stimulation for cerebral palsy--double blind study.

    PubMed

    Davis, R; Schulman, J; Delehanty, A

    1987-01-01

    Twenty spastic cerebral palsy (CP) patients undergoing chronic cerebellar stimulation (CCS) for reduction of spasticity and improvement in function have participated in a double-blind study. Seven US centers involving 9 neurosurgeons (1984-6) have replaced the depleted Neurolith 601 fully implantable pulse generator (Pacesetter Systems Incorp.-Neurodyne Corp., Sylmar, CA) with new units in 19 CP patients, 1 patient entered the study following his initial implant. A magnetically controllable switch was placed in line between the Neurolith stimulator and the cerebellar lead, so allowing switching sequences for the study. Physical therapists, living in the vicinity of the patient's home, carried out two quantitative evaluations: 1. Joint angle motion measurements (passive and active). 2. Motor performance testing was done when possible and included: reaction time, hand dynamonetry, grooved peg board placement, hand/foot tapping, and rotary pursuit testing. Testing was done presurgery, at 2 weeks postimplant, then the switch was activated either "on" or "off" to a schedule, with testing and reswitching at 1, 2 and 4 months, then the switch was left turned "on". Of the 20 patients, 16 finished the tests, 2 patients failed to finish and 2 had switch problems and were deleted from the study. Two of the 16 patients were "off" through the entire testing. Of the 14 that had periods of the stimulator being "on", 10 patients (72%) had quantitative improvements of over 20%, (1 pt: 50+% improvements; 4 pts: 30-50%, 5 pts: 20-30%); while 1 patient (7%) had improvements in the 10-20% level, whereas 3 patients (21%) showed no improvement.

  4. Contamination Control in Ion Implantation

    SciTech Connect

    Eddy, R.; Doi, D.; Santos, I.; Wriggins, W.

    2011-01-07

    The investigation and elimination or control of metallic contamination in ion implanters has been a leading, continuous effort at implanter OEMs and in fabs/IDMs alike. Much of the efforts have been in the area of control of sputtering through material and geometry changes in apertures, beamline and target chamber components. In this paper, we will focus on an area that has not, heretofore, been fully investigated or controlled. This is the area of lubricants and internal and external support material such as selected cleaning media. Some of these materials are designated for internal use (beamline/vacuum) only while others are for internal and/or external use. Many applications for selected greases, for example, are designated for or are used for platens, implant disks/wheels and for wafer handling components. We will present data from popular lubricants (to be unnamed) used worldwide in ion implanters. This paper will review elements of concern in many lubricants that should be tracked and monitored by all fabs.Proper understanding of the characteristics, risks and the control of these potential contaminants can provide for rapid return to full process capability following major PMs or parts changes. Using VPD-ICPMS, Glow Discharge Mass Spectrometry and Ion Chromatography (IC) data, we will review the typical cleaning results and correlation to ''on wafer'' contamination by elements of concern--and by some elements that are otherwise barred from the fab.

  5. Miniaturized neural interfaces and implants

    NASA Astrophysics Data System (ADS)

    Stieglitz, Thomas; Boretius, Tim; Ordonez, Juan; Hassler, Christina; Henle, Christian; Meier, Wolfgang; Plachta, Dennis T. T.; Schuettler, Martin

    2012-03-01

    Neural prostheses are technical systems that interface nerves to treat the symptoms of neurological diseases and to restore sensory of motor functions of the body. Success stories have been written with the cochlear implant to restore hearing, with spinal cord stimulators to treat chronic pain as well as urge incontinence, and with deep brain stimulators in patients suffering from Parkinson's disease. Highly complex neural implants for novel medical applications can be miniaturized either by means of precision mechanics technologies using known and established materials for electrodes, cables, and hermetic packages or by applying microsystems technologies. Examples for both approaches will be introduced and discussed. Electrode arrays for recording of electrocorticograms during presurgical epilepsy diagnosis have been manufactured using approved materials and a marking laser to achieve an integration density that is adequate in the context of brain machine interfaces, e.g. on the motor cortex. Microtechnologies have to be used for further miniaturization to develop polymer-based flexible and light weighted electrode arrays to interface the peripheral and central nervous system. Polyimide as substrate and insulation material will be discussed as well as several application examples for nerve interfaces like cuffs, filament like electrodes and large arrays for subdural implantation.

  6. The multiple-channel cochlear implant: the interface between sound and the central nervous system for hearing, speech, and language in deaf people—a personal perspective

    PubMed Central

    Clark, Graeme M

    2006-01-01

    The multiple-channel cochlear implant is the first sensori-neural prosthesis to effectively and safely bring electronic technology into a direct physiological relation with the central nervous system and human consciousness, and to give speech perception to severely-profoundly deaf people and spoken language to children. Research showed that the place and temporal coding of sound frequencies could be partly replicated by multiple-channel stimulation of the auditory nerve. This required safety studies on how to prevent the effects to the cochlea of trauma, electrical stimuli, biomaterials and middle ear infection. The mechanical properties of an array and mode of stimulation for the place coding of speech frequencies were determined. A fully implantable receiver–stimulator was developed, as well as the procedures for the clinical assessment of deaf people, and the surgical placement of the device. The perception of electrically coded sounds was determined, and a speech processing strategy discovered that enabled late-deafened adults to comprehend running speech. The brain processing systems for patterns of electrical stimuli reproducing speech were elucidated. The research was developed industrially, and improvements in speech processing made through presenting additional speech frequencies by place coding. Finally, the importance of the multiple-channel cochlear implant for early deafened children was established. PMID:16627295

  7. The use of acupuncture in implant dentistry.

    PubMed

    Vachiramon, Amornpong; Wang, Wendy C; Vachiramon, Tharin

    2004-03-01

    This article aims to review how acupuncture can provide complimentary treatments to patients through implant rehabilitation. The following topics are discussed: control of gagging reflex, control of postoperative vomiting, control of postoperative pain, enhance anesthetic effects, control of anxiety, increase saliva production, enhance immune responses, management of temporomandibular dysfunction, smoking cessation, control diabetic mellitus, stimulation of peripheral nerve regeneration, and adverse effects. PMID:15017306

  8. Wireless Performance of a Fully Passive Neurorecording Microsystem Embedded in Dispersive Human Head Phantom

    NASA Technical Reports Server (NTRS)

    Schwerdt, Helen N.; Chae, Junseok; Miranda, Felix A.

    2012-01-01

    This paper reports the wireless performance of a biocompatible fully passive microsystem implanted in phantom media simulating the dispersive dielectric properties of the human head, for potential application in recording cortical neuropotentials. Fully passive wireless operation is achieved by means of backscattering electromagnetic (EM) waves carrying 3rd order harmonic mixing products (2f(sub 0) plus or minus f(sub m)=4.4-4.9 GHZ) containing targeted neuropotential signals (fm approximately equal to 1-1000 Hz). The microsystem is enclosed in 4 micrometer thick parylene-C for biocompatibility and has a footprint of 4 millimeters x 12 millimeters x 500 micrometers. Preliminary testing of the microsystem implanted in the lossy biological simulating media results in signal-to-noise ratio's (SNR) near 22 (SNR approximately equal to 38 in free space) for millivolt level neuropotentials, demonstrating the potential for fully passive wireless microsystems in implantable medical applications.

  9. Chimeric Peptides as Implant Functionalization Agents for Titanium Alloy Implants with Antimicrobial Properties

    NASA Astrophysics Data System (ADS)

    Yucesoy, Deniz T.; Hnilova, Marketa; Boone, Kyle; Arnold, Paul M.; Snead, Malcolm L.; Tamerler, Candan

    2015-04-01

    Implant-associated infections can have severe effects on the longevity of implant devices and they also represent a major cause of implant failures. Treating these infections associated with implants by antibiotics is not always an effective strategy due to poor penetration rates of antibiotics into biofilms. Additionally, emerging antibiotic resistance poses serious concerns. There is an urge to develop effective antibacterial surfaces that prevent bacterial adhesion and proliferation. A novel class of bacterial therapeutic agents, known as antimicrobial peptides (AMPs), are receiving increasing attention as an unconventional option to treat septic infection, partly due to their capacity to stimulate innate immune responses and for the difficulty of microorganisms to develop resistance towards them. While host and bacterial cells compete in determining the ultimate fate of the implant, functionalization of implant surfaces with AMPs can shift the balance and prevent implant infections. In the present study, we developed a novel chimeric peptide to functionalize the implant material surface. The chimeric peptide simultaneously presents two functionalities, with one domain binding to a titanium alloy implant surface through a titanium-binding domain while the other domain displays an antimicrobial property. This approach gains strength through control over the bio-material interfaces, a property built upon molecular recognition and self-assembly through a titanium alloy binding domain in the chimeric peptide. The efficiency of chimeric peptide both in-solution and absorbed onto titanium alloy surface was evaluated in vitro against three common human host infectious bacteria, Streptococcus mutans, Staphylococcus epidermidis, and Escherichia coli. In biological interactions such as occur on implants, it is the surface and the interface that dictate the ultimate outcome. Controlling the implant surface by creating an interface composed chimeric peptides may therefore

  10. Chimeric peptides as implant functionalization agents for titanium alloy implants with antimicrobial properties

    PubMed Central

    Yucesoy, Deniz T.; Hnilova, Marketa; Boone, Kyle; Arnold, Paul M.; Snead, Malcolm L.

    2015-01-01

    Implant-associated infections can have severe effects on the longevity of implant devices and they also represent a major cause of implant failures. Treating these infections associated with implants by antibiotics is not always an effective strategy due to poor penetration rates of antibiotics into biofilms. Additionally, emerging antibiotic resistance poses serious concerns. There is an urge to develop effective antibacterial surfaces that prevent bacterial adhesion and proliferation. A novel class of bacterial therapeutic agents, known as antimicrobial peptides (AMP’s), are receiving increasing attention as an unconventional option to treat septic infection, partly due to their capacity to stimulate innate immune responses and for the difficulty of microorganisms to develop resistance towards them. While host- and bacterial- cells compete in determining the ultimate fate of the implant, functionalization of implant surfaces with antimicrobial peptides can shift the balance and prevent implant infections. In the present study, we developed a novel chimeric peptide to functionalize the implant material surface. The chimeric peptide simultaneously presents two functionalities, with one domain binding to a titanium alloy implant surface through a titanium-binding domain while the other domain displays an antimicrobial property. This approach gains strength through control over the bio-material interfaces, a property built upon molecular recognition and self-assembly through a titanium alloy binding domain in the chimeric peptide. The efficiency of chimeric peptide both in-solution and absorbed onto titanium alloy surface was evaluated in vitro against three common human host infectious bacteria, S. mutans, S. epidermidis, and E. coli. In biological interactions such as occurs on implants, it is the surface and the interface that dictate the ultimate outcome. Controlling the implant surface by creating an interface composed chimeric peptides may therefore open up

  11. Microsystem technologies for ophtalmological implants

    NASA Astrophysics Data System (ADS)

    Mokwa, Wilfried

    2003-01-01

    Due to the low power consumption CMOS electronics is ideal for the use in implanted systems. This paper presents two projects working on ophthalmological implants. Both systems are powered by an external RF-field. One system has been developed to measure the intraocular pressure continuously which is important for the therapy of glaucoma patients. The system consists of a micro coil and an integrated pressure transponder chip built into an artificial soft lens. A second example is a very complex system for epiretinal stimulation of the nerve cells of the retina. With such a system it might be possible to give blind people that are suffering from retinitis pigmentosa some visual contact to their surrounding.

  12. Fully Integrating the Design Process

    SciTech Connect

    T.A. Bjornard; R.S. Bean

    2008-03-01

    The basic approach to designing nuclear facilities in the United States does not currently reflect the routine consideration of proliferation resistance and international safeguards. The fully integrated design process is an approach for bringing consideration of international safeguards and proliferation resistance, together with state safeguards and security, fully into the design process from the very beginning, while integrating them sensibly and synergistically with the other project functions. In view of the recently established GNEP principles agreed to by the United States and at least eighteen other countries, this paper explores such an integrated approach, and its potential to help fulfill the new internationally driven design requirements with improved efficiencies and reduced costs.

  13. Implantable Myoelectric Sensors (IMESs) for Intramuscular Electromyogram Recording

    PubMed Central

    Weir, Richard F. ff.; Troyk, Phil R.; DeMichele, Glen A.; Kerns, Douglas A.; Schorsch, Jack F.; Maas, Huub

    2011-01-01

    We have developed a multichannel electrogmyography sensor system capable of receiving and processing signals from up to 32 implanted myoelectric sensors (IMES). The appeal of implanted sensors for myoelectric control is that electromyography (EMG) signals can be measured at their source providing relatively cross-talk-free signals that can be treated as independent control sites. An external telemetry controller receives telemetry sent over a transcutaneous magnetic link by the implanted electrodes. The same link provides power and commands to the implanted electrodes. Wireless telemetry of EMG signals from sensors implanted in the residual musculature eliminates the problems associated with percutaneous wires, such as infection, breakage, and marsupialization. Each implantable sensor consists of a custom-designed application-specified integrated circuit that is packaged into a bio-compatible RF BION capsule from the Alfred E. Mann Foundation. Implants are designed for permanent long-term implantation with no servicing requirements. We have a fully operational system. The system has been tested in animals. Implants have been chronically implanted in the legs of three cats and are still completely operational four months after implantation. PMID:19224729

  14. The feasibility of immediately loading dental implants in edentulous jaws

    PubMed Central

    2016-01-01

    Purpose Immediate loading of dental implants has been proved to be feasible in partially edentulous jaws. The purpose of this retrospective investigation was to assess the feasibility of immediately loading dental implants in fully edentulous jaws. Methods A total of 24 patients aged between 53 and 89 years received a total of 154 implants in their edentulous maxillae or mandibles. Among the implants, 45 were set in fresh extracted sockets and 109 in consolidated alveolar bones. The implants were provisionally managed with chair-side made provisional resin bridges and exposed to immediate loading. Implants were followed up for 1–8 years, including radiographic imaging. Marginal bone levels were evaluated based on radiographic imaging. Results A total of 148 out of the 154 implants survived over the follow-up period of 1 to 8 years, giving a survival rate of 96%. The time or region of the implantation, the pre-implant augmentation, and the length and diameter of the implants had no statistically significant influence on the survival or the success rate. The marginal bone level remained stable with only minimal loss of 0.3 mm after 60 months of loading. Conclusions Within the limitations of this study, immediate loading is feasible for dental implants in edentulous jaws. PMID:27588213

  15. Bizarre Paranoid Delusions Associated With an Implanted Surgical Device.

    PubMed

    Dodds, Peter R; Dodds, Tyler J; Jacoby, Teri L

    2016-03-01

    We describe a case involving bizarre paranoid delusions following implantation of a sacral nerve stimulator, and review the literature regarding psychotic symptoms related to surgical implants. A 64-year-old female developed bizarre paranoid delusions regarding a sacral nerve stimulator that had been implanted two years previously for dysfunctional voiding. The patient believed that the wires from the sacral nerve electrodes had grown up her spine and were affecting her vision as well as controlling her thoughts. The delusions developed in the setting of profound anxiety and feelings of loss after the death of her mother. The patient initially demanded that the implant be removed emergently. The delusions gradually abated as she adjusted to the loss of her mother. Fortunately the symptoms abated entirely with supportive care. We suspect that given the frequency of surgical implants that the association with delusional thoughts might be much higher than suggested by a literature review. PMID:27169299

  16. Adherent endotoxin on dental implant surfaces: a reappraisal.

    PubMed

    Morra, Marco; Cassinelli, Clara; Bollati, Daniele; Cascardo, Giovanna; Bellanda, Marco

    2015-02-01

    Osteoimmunology is the crosstalk between cells from the immune and skeletal systems, suggesting a role of pro-inflammatory cytokines in the stimulation of osteoclast activity. Endotoxin or bacterial challenges to inflammatory cells are directly relevant to dental implant pathologies involving bone resorption, such as osseointegration failure and peri-implantitis. While the endotoxin amount on implant devices is regulated by standards, it is unknown whether commercially available dental implants elicit different levels of adherent-endotoxin stimulated cytokines. The objective of this work is to develop a model system and evaluate endotoxin-induced expression of pro-inflammatory cytokine genes relevant to osteoclast activation on commercially available dental implants. Murine J774-A1 macrophages were cultured on Ti disks with different level of lipopolysaccharide (LPS) contamination to define the time-course of the inflammatory response to endotoxin, as evaluated by reverse transcription polymerase chain reaction analysis. The developed protocol was then used to measure adherent endotoxin on commercially available packaged and sterile dental implants in the "as-implanted" condition. Results show that tested dental implants induce variable expression of endotoxin-stimulated genes, sometimes above the level expected to promote bone resorption in vivo. Results are unaffected by the specific surface treatment; rather, they likely reflect care in cleaning and packaging protocols. In conclusion, expression of genes that enhance osteoclast activity through endotoxin stimulation of inflammatory cells is widely different on commercially available dental implants. A reappraisal of the clinical impact of adherent endotoxins on dental (and bone) implant devices is required in light of increasing knowledge on crosstalk between cells from the immune and skeletal systems.

  17. Implant success!!!.....simplified.

    PubMed

    Luthra, Kaushal K

    2009-01-01

    The endeavor towards life-like restoration has helped nurture new vistas in the art and science of implant dentistry. The protocol of "restoration-driven implant placement" ensures that the implant is an apical extension of the ideal future restoration and not the opposite. Meticulous pre-implant evaluation of soft and hard tissues, diagnostic cast and use of aesthetic wax-up and radiographic template combined with surgical template can simplify the intricate roadmap for appropriate implant treatment.By applying the harmony of artistic skill, scientific knowledge and clinical expertise, we can simply master the outstanding implant success in requisites of aesthetics, phonetics and function.

  18. Toward a fully integrated neurostimulator with inductive power recovery front-end.

    PubMed

    Mounaïm, Fayçal; Sawan, Mohamad

    2012-08-01

    In order to investigate new neurostimulation strategies for micturition recovery in spinal cord injured patients, custom implantable stimulators are required to carry-on chronic animal experiments. However, higher integration of the neurostimulator becomes increasingly necessary for miniaturization purposes, power consumption reduction, and for increasing the number of stimulation channels. As a first step towards total integration, we present in this paper the design of a highly-integrated neurostimulator that can be assembled on a 21-mm diameter printed circuit board. The prototype is based on three custom integrated circuits fabricated in High-Voltage (HV) CMOS technology, and a low-power small-scale commercially available FPGA. Using a step-down approach where the inductive voltage is left free up to 20 V, the inductive power and data recovery front-end is fully integrated. In particular, the front-end includes a bridge rectifier, a 20-V voltage limiter, an adjustable series regulator (5 to 12 V), a switched-capacitor step-down DC/DC converter (1:3, 1:2, or 2:3 ratio), as well as data recovery. Measurements show that the DC/DC converter achieves more than 86% power efficiency while providing around 3.9-V from a 12-V input at 1-mA load, 1:3 conversion ratio, and 50-kHz switching frequency. With such efficiency, the proposed step-down inductive power recovery topology is more advantageous than its conventional step-up counterpart. Experimental results confirm good overall functionality of the system. PMID:23853175

  19. Toward a fully integrated neurostimulator with inductive power recovery front-end.

    PubMed

    Mounaïm, Fayçal; Sawan, Mohamad

    2012-08-01

    In order to investigate new neurostimulation strategies for micturition recovery in spinal cord injured patients, custom implantable stimulators are required to carry-on chronic animal experiments. However, higher integration of the neurostimulator becomes increasingly necessary for miniaturization purposes, power consumption reduction, and for increasing the number of stimulation channels. As a first step towards total integration, we present in this paper the design of a highly-integrated neurostimulator that can be assembled on a 21-mm diameter printed circuit board. The prototype is based on three custom integrated circuits fabricated in High-Voltage (HV) CMOS technology, and a low-power small-scale commercially available FPGA. Using a step-down approach where the inductive voltage is left free up to 20 V, the inductive power and data recovery front-end is fully integrated. In particular, the front-end includes a bridge rectifier, a 20-V voltage limiter, an adjustable series regulator (5 to 12 V), a switched-capacitor step-down DC/DC converter (1:3, 1:2, or 2:3 ratio), as well as data recovery. Measurements show that the DC/DC converter achieves more than 86% power efficiency while providing around 3.9-V from a 12-V input at 1-mA load, 1:3 conversion ratio, and 50-kHz switching frequency. With such efficiency, the proposed step-down inductive power recovery topology is more advantageous than its conventional step-up counterpart. Experimental results confirm good overall functionality of the system.

  20. Fully depleted back illuminated CCD

    DOEpatents

    Holland, Stephen Edward

    2001-01-01

    A backside illuminated charge coupled device (CCD) is formed of a relatively thick high resistivity photon sensitive silicon substrate, with frontside electronic circuitry, and an optically transparent backside ohmic contact for applying a backside voltage which is at least sufficient to substantially fully deplete the substrate. A greater bias voltage which overdepletes the substrate may also be applied. One way of applying the bias voltage to the substrate is by physically connecting the voltage source to the ohmic contact. An alternate way of applying the bias voltage to the substrate is to physically connect the voltage source to the frontside of the substrate, at a point outside the depletion region. Thus both frontside and backside contacts can be used for backside biasing to fully deplete the substrate. Also, high resistivity gaps around the CCD channels and electrically floating channel stop regions can be provided in the CCD array around the CCD channels. The CCD array forms an imaging sensor useful in astronomy.

  1. Multiscale design and multiobjective optimization of orthopedic hip implants with functionally graded cellular material.

    PubMed

    Arabnejad Khanoki, Sajad; Pasini, Damiano

    2012-03-01

    Revision surgeries of total hip arthroplasty are often caused by a deficient structural compatibility of the implant. Two main culprits, among others, are bone-implant interface instability and bone resorption. To address these issues, in this paper we propose a novel type of implant, which, in contrast to current hip replacement implants made of either a fully solid or a foam material, consists of a lattice microstructure with nonhomogeneous distribution of material properties. A methodology based on multiscale mechanics and design optimization is introduced to synthesize a graded cellular implant that can minimize concurrently bone resorption and implant interface failure. The procedure is applied to the design of a 2D left implanted femur with optimized gradients of relative density. To assess the manufacturability of the graded cellular microstructure, a proof-of-concept is fabricated by using rapid prototyping. The results from the analysis are used to compare the optimized cellular implant with a fully dense titanium implant and a homogeneous foam implant with a relative density of 50%. The bone resorption and the maximum value of interface stress of the cellular implant are found to be over 70% and 50% less than the titanium implant while being 53% and 65% less than the foam implant.

  2. Fully synthetic taped insulation cables

    DOEpatents

    Forsyth, Eric B.; Muller, Albert C.

    1984-01-01

    A high voltage oil-impregnated electrical cable with fully polymer taped insulation operable to 765 kV. Biaxially oriented, specially processed, polyethylene, polybutene or polypropylene tape with an embossed pattern is wound in multiple layers over a conductive core with a permeable screen around the insulation. Conventional oil which closely matches the dielectric constant of the tape is used, and the cable can be impregnated after field installation because of its excellent impregnation characteristics.

  3. Fully automated urban traffic system

    NASA Technical Reports Server (NTRS)

    Dobrotin, B. M.; Hansen, G. R.; Peng, T. K. C.; Rennels, D. A.

    1977-01-01

    The replacement of the driver with an automatic system which could perform the functions of guiding and routing a vehicle with a human's capability of responding to changing traffic demands was discussed. The problem was divided into four technological areas; guidance, routing, computing, and communications. It was determined that the latter three areas being developed independent of any need for fully automated urban traffic. A guidance system that would meet system requirements was not being developed but was technically feasible.

  4. [Biomaterials in cochlear implants].

    PubMed

    Stöver, T; Lenarz, T

    2009-05-01

    Cochlear implants (CI) represent the "gold standard" for the treatment of congenitally deaf children and postlingually deafened adults. Thus, cochlear implantation is a success story of new bionic prosthesis development. Owing to routine application of cochlear implants in adults but also in very young children (below the age of one), high demands are placed on the implants. This is especially true for biocompatibility aspects of surface materials of implant parts which are in contact with the human body. In addition, there are various mechanical requirements which certain components of the implants must fulfil, such as flexibility of the electrode array and mechanical resistance of the implant housing. Due to the close contact of the implant to the middle ear mucosa and because the electrode array is positioned in the perilymphatic space via cochleostomy, there is a potential risk of bacterial transferral along the electrode array into the cochlea. Various requirements that have to be fulfilled by cochlear implants, such as biocompatibility, electrode micromechanics, and although a very high level of technical standards has been carried out there is still demand for the improvement of implants as well as of the materials used for manufacturing, ultimately leading to increased implant performance. General considerations of material aspects related to cochlear implants as well as potential future perspectives of implant development will be discussed.

  5. Cellular Responses Evoked by Different Surface Characteristics of Intraosseous Titanium Implants

    PubMed Central

    Feller, Liviu; Jadwat, Yusuf; Khammissa, Razia A. G.; Meyerov, Robin; Lemmer, Johan

    2015-01-01

    The properties of biomaterials, including their surface microstructural topography and their surface chemistry or surface energy/wettability, affect cellular responses such as cell adhesion, proliferation, and migration. The nanotopography of moderately rough implant surfaces enhances the production of biological mediators in the peri-implant microenvironment with consequent recruitment of differentiating osteogenic cells to the implant surface and stimulates osteogenic maturation. Implant surfaces with moderately rough topography and with high surface energy promote osteogenesis, increase the ratio of bone-to-implant contact, and increase the bonding strength of the bone to the implant at the interface. Certain features of implant surface chemistry are also important in enhancing peri-implant bone wound healing. It is the purpose of this paper to review some of the more important features of titanium implant surfaces which have an impact on osseointegration. PMID:25767803

  6. MEMS technologies for epiretinal stimulation of the retina

    NASA Astrophysics Data System (ADS)

    Mokwa, W.

    2004-09-01

    It has been shown that electrical stimulation of retinal ganglion cells yields visual sensations. Therefore, a retina implant for blind humans suffering from retinitis pigmentosa based on this concept seems to be feasible. In Germany, there are two projects funded by the government working on different approaches namely the subretinal and the epiretinal approaches. This paper describes the epiretinal approach for such a system. The extraocular part of this system records visual images. The images are transformed by a neural net into corresponding signals for stimulation of the retinal ganglion cells. These signals are transmitted to a receiver unit of an intraocular implant, the retina stimulator. Integrated circuitry of this unit decodes the signals and transfers the data to a stimulation circuitry that selects stimulation electrodes placed onto the retina and generates current pulses to the electrodes. By this, action potentials in retinal ganglion cells are evoked, causing a visual sensation. This paper concentrates on the MEMS part of this implant.

  7. Surface characterization of commercial oral implants on the nanometer level.

    PubMed

    Svanborg, Lory Melin; Andersson, Martin; Wennerberg, Ann

    2010-02-01

    Lately, there has been a growing interest in how the presence of nanometer structures on a bone integrated implant surface influences the healing process. Recent in vitro studies have revealed an increased osteoblast response to different nanophase surfaces. Some commercial implant brands claim their implants have nanometer structures. However, at present, there are no studies where the nano topography of today's commercially available oral implants has been investigated. The aim of this study was to characterize commercial oral implants on the nanometer level and to investigate whether or not the nanometer surface roughness was correlated to the more well-known micrometer roughness on the implants. Twelve different commercial screw-shaped oral implants with various surface modifications were examined using scanning electron microscopy and a white light interferometer. The interferometer is suitable for detection of nanoscale roughness in the vertical dimension; however, limitation exists on the horizontal due to the wavelength of the light. A 1 x 1 microm Gaussian filter was found to be useful for identifying nm roughness with respect to height deviation. The results demonstrated that an implant that was smooth on the micrometer level was not necessarily smooth on the nanometer level. Different structures in the nanometer scale was found on some of the implants, indicating that to fully understand the relationship between the properties of an implant surface and its osseointegration behavior, a characterization at the nanometer scale might be relevant.

  8. Breast reconstruction - implants

    MedlinePlus

    ... visits, your surgeon injects a small amount of saline (salt water) through the valve into the expander. ... breast implants. Implants may be filled with either saline or a silicone gel. You may have another ...

  9. Additively manufactured porous tantalum implants.

    PubMed

    Wauthle, Ruben; van der Stok, Johan; Amin Yavari, Saber; Van Humbeeck, Jan; Kruth, Jean-Pierre; Zadpoor, Amir Abbas; Weinans, Harrie; Mulier, Michiel; Schrooten, Jan

    2015-03-01

    The medical device industry's interest in open porous, metallic biomaterials has increased in response to additive manufacturing techniques enabling the production of complex shapes that cannot be produced with conventional techniques. Tantalum is an important metal for medical devices because of its good biocompatibility. In this study selective laser melting technology was used for the first time to manufacture highly porous pure tantalum implants with fully interconnected open pores. The architecture of the porous structure in combination with the material properties of tantalum result in mechanical properties close to those of human bone and allow for bone ingrowth. The bone regeneration performance of the porous tantalum was evaluated in vivo using an orthotopic load-bearing bone defect model in the rat femur. After 12 weeks, substantial bone ingrowth, good quality of the regenerated bone and a strong, functional implant-bone interface connection were observed. Compared to identical porous Ti-6Al-4V structures, laser-melted tantalum shows excellent osteoconductive properties, has a higher normalized fatigue strength and allows for more plastic deformation due to its high ductility. It is therefore concluded that this is a first step towards a new generation of open porous tantalum implants manufactured using selective laser melting.

  10. Additively manufactured porous tantalum implants.

    PubMed

    Wauthle, Ruben; van der Stok, Johan; Amin Yavari, Saber; Van Humbeeck, Jan; Kruth, Jean-Pierre; Zadpoor, Amir Abbas; Weinans, Harrie; Mulier, Michiel; Schrooten, Jan

    2015-03-01

    The medical device industry's interest in open porous, metallic biomaterials has increased in response to additive manufacturing techniques enabling the production of complex shapes that cannot be produced with conventional techniques. Tantalum is an important metal for medical devices because of its good biocompatibility. In this study selective laser melting technology was used for the first time to manufacture highly porous pure tantalum implants with fully interconnected open pores. The architecture of the porous structure in combination with the material properties of tantalum result in mechanical properties close to those of human bone and allow for bone ingrowth. The bone regeneration performance of the porous tantalum was evaluated in vivo using an orthotopic load-bearing bone defect model in the rat femur. After 12 weeks, substantial bone ingrowth, good quality of the regenerated bone and a strong, functional implant-bone interface connection were observed. Compared to identical porous Ti-6Al-4V structures, laser-melted tantalum shows excellent osteoconductive properties, has a higher normalized fatigue strength and allows for more plastic deformation due to its high ductility. It is therefore concluded that this is a first step towards a new generation of open porous tantalum implants manufactured using selective laser melting. PMID:25500631

  11. [Pathology of implants].

    PubMed

    Mittermayer, C; Eblenkamp, M; Richter, H A; Zwadlo-Klarwasser, G; Bhardwaj, R S; Klosterhalfen, B

    2002-01-01

    Progress in the surgery of implants and biomaterials can be accomplished by: 1. Painstakingly analysing and registering of defaulting implants after explantation within a "National Registry of Implant Pathology". 2. Development of a DNA-microarray named "Implantat/Chronic Wound" in order to discover the differential transcriptional activities of cells brought into contact with different foreign surfaces. 3. Predictive cell-engineering combined with custom-made implant surfaces with the aim of optimal patient care.

  12. Electroacoustic Stimulation: Now and into the Future

    PubMed Central

    Irving, S.; Gillespie, L.; Richardson, R.; Rowe, D.; Fallon, J. B.; Wise, A. K.

    2014-01-01

    Cochlear implants have provided hearing to hundreds of thousands of profoundly deaf people around the world. Recently, the eligibility criteria for cochlear implantation have been relaxed to include individuals who have some useful residual hearing. These recipients receive inputs from both electric and acoustic stimulation (EAS). Implant recipients who can combine these hearing modalities demonstrate pronounced benefit in speech perception, listening in background noise, and music appreciation over implant recipients that rely on electrical stimulation alone. The mechanisms bestowing this benefit are unknown, but it is likely that interaction of the electric and acoustic signals in the auditory pathway plays a role. Protection of residual hearing both during and following cochlear implantation is critical for EAS. A number of surgical refinements have been implemented to protect residual hearing, and the development of hearing-protective drug and gene therapies is promising for EAS recipients. This review outlines the current field of EAS, with a focus on interactions that are observed between these modalities in animal models. It also outlines current trends in EAS surgery and gives an overview of the drug and gene therapies that are clinically translatable and may one day provide protection of residual hearing for cochlear implant recipients. PMID:25276779

  13. Wireless magnetothermal deep brain stimulation.

    PubMed

    Chen, Ritchie; Romero, Gabriela; Christiansen, Michael G; Mohr, Alan; Anikeeva, Polina

    2015-03-27

    Wireless deep brain stimulation of well-defined neuronal populations could facilitate the study of intact brain circuits and the treatment of neurological disorders. Here, we demonstrate minimally invasive and remote neural excitation through the activation of the heat-sensitive capsaicin receptor TRPV1 by magnetic nanoparticles. When exposed to alternating magnetic fields, the nanoparticles dissipate heat generated by hysteresis, triggering widespread and reversible firing of TRPV1(+) neurons. Wireless magnetothermal stimulation in the ventral tegmental area of mice evoked excitation in subpopulations of neurons in the targeted brain region and in structures receiving excitatory projections. The nanoparticles persisted in the brain for over a month, allowing for chronic stimulation without the need for implants and connectors. PMID:25765068

  14. Longitudinal performance of an implantable vestibular prosthesis

    PubMed Central

    Phillips, Christopher; Ling, Leo; Oxford, Trey; Nowack, Amy; Nie, Kaibao; Rubinstein, Jay T.; Phillips, James O.

    2014-01-01

    Loss of vestibular function may be treatable with an implantable vestibular prosthesis that stimulates semicircular canal afferents with biphasic pulse trains. Several studies have demonstrated short-term activation of the vestibulo-ocular reflex (VOR) with electrical stimulation. Fewer long-term studies have been restricted to small numbers of animals and stimulation designed to produce adaptive changes in the electrically elicited response. This study is the first large consecutive series of implanted rhesus macaque to be studied longitudinally using brief stimuli designed to limit adaptive changes in response, so that the efficacy of electrical activation can be studied over time, across surgeries, canals and animals. The implantation of a vestibular prosthesis in animals with intact vestibular end organs produces variable responses to electrical stimulation across canals and animals, which change in threshold for electrical activation of eye movements and in elicited slow phase velocities over time. These thresholds are consistently lower, and the slow phase velocities higher, than those obtained in human subjects. The changes do not appear to be correlated with changes in electrode impedance. The variability in response suggests that empirically derived transfer functions may be required to optimize the response of individual canals to a vestibular prosthesis, and that this function may need to be remapped over time. PMID:25245586

  15. Implantable Heart Aid

    NASA Technical Reports Server (NTRS)

    1984-01-01

    CPI's human-implantable automatic implantable defibrillator (AID) is a heart assist system, derived from NASA's space circuitry technology, that can prevent erratic heart action known as arrhythmias. Implanted AID, consisting of microcomputer power source and two electrodes for sensing heart activity, recognizes onset of ventricular fibrillation (VF) and delivers corrective electrical countershock to restore rhythmic heartbeat.

  16. Biomechanical determinants of the stability of dental implants: influence of the bone-implant interface properties.

    PubMed

    Mathieu, Vincent; Vayron, Romain; Richard, Gilles; Lambert, Grégory; Naili, Salah; Meningaud, Jean-Paul; Haiat, Guillaume

    2014-01-01

    Dental implants are now widely used for the replacement of missing teeth in fully or partially edentulous patients and for cranial reconstructions. However, risks of failure, which may have dramatic consequences, are still experienced and remain difficult to anticipate. The stability of biomaterials inserted in bone tissue depends on multiscale phenomena of biomechanical (bone-implant interlocking) and of biological (mechanotransduction) natures. The objective of this review is to provide an overview of the biomechanical behavior of the bone-dental implant interface as a function of its environment by considering in silico, ex vivo and in vivo studies including animal models as well as clinical studies. The biomechanical determinants of osseointegration phenomena are related to bone remodeling in the vicinity of the implants (adaptation of the bone structure to accommodate the presence of a biomaterial). Aspects related to the description of the interface and to its space-time multiscale nature will first be reviewed. Then, the various approaches used in the literature to measure implant stability and the bone-implant interface properties in vitro and in vivo will be described. Quantitative ultrasound methods are promising because they are cheap, non invasive and because of their lower spatial resolution around the implant compared to other biomechanical approaches.

  17. Biocompatibility of implantable biomedical devices

    NASA Astrophysics Data System (ADS)

    Lyu, Suping

    2008-03-01

    Biomedical devices have been broadly used to treat human disease, especially chronic diseases where pharmaceuticals are less effective. Heart valve and artificial joint are examples. Biomedical devices perform by delivering therapies such as electric stimulations, mechanical supports and biological actions. While the uses of biomedical devices are highly successful they can trigger adverse biological reactions as well. The property that medical devices perform with intended functions but not causing unacceptable adverse effects was called biocompatibility in the early time. As our understanding of biomaterial-biological interactions getting broader, biocompatibility has more meanings. In this talk, I will present some adverse biological reactions observed with implantable biomedical devices. Among them are surface fouling of implantable sensors, calcification with vascular devices, restenosis with stents, foreign particle migration and mechanical fractures of devices due to inflammation reactions. While these effects are repeatable, there are very few quantitative data and theories to define them. The purpose of this presentation is to introduce this biocompatibility concept to biophysicists to stimulate research interests at different angles. An open question is how to quantitatively understand the biocompatibility that, like many other biological processes, has not been quantified experimentally.

  18. Treatment of neurological and psychiatric disorders with deep brain stimulation; raising hopes and future challenges.

    PubMed

    Sharifi, Mohammad Sharif

    2013-01-01

    The technology of Neural Stimulation in recent years has become the focus of the research and treatment, although it has been around for many years. The potential use of stimulating the brain and nerves ranges from the spinal cord stimulation to the implantations of cochlear and bionic eyes with a large discrepancy between the clinical readiness for these various uses. Electrical high-frequency Deep Brain Stimulation (DBS) was developed as an alternative option to treat a few neurological disorders. However, with advancing in surgical procedures, technologies and safeties, the applications of DBS are expanding not only for therapeutic purposes but also for research. Although the exact mechanisms of action/s are not fully understood, the outcome of the ongoing research and clinical trials are promising. DBS has been used to treat the essential tremor since 1997, Parkinson's disease (PD) since 2002 and dystonia since 2003. It has also been used to treat various disorders, including major depression. The therapeutic effect of DBS in PD is well established but for other diseases such as epilepsy the outcomes are unclear and ambiguous. This article is a succinct review of the literature, focusing on PD, epilepsy and Obsessive Compulsive Disorder (OCD). PMID:25337356

  19. Theoretical model of a piezoelectric composite spinal fusion interbody implant.

    PubMed

    Tobaben, Nicholas E; Domann, John P; Arnold, Paul M; Friis, Elizabeth A

    2014-04-01

    Failure rates of spinal fusion are high in smokers and diabetics. The authors are investigating the development of a piezoelectric composite biomaterial and interbody device design that could generate clinically relevant levels of electrical stimulation to help improve the rate of fusion for these patients. A lumped parameter model of the piezoelectric composite implant was developed based on a model that has been utilized to successfully predict power generation for piezoceramics. Seven variables (fiber material, matrix material, fiber volume fraction, fiber aspect ratio, implant cross-sectional area, implant thickness, and electrical load resistance) were parametrically analyzed to determine their effects on power generation within reasonable implant constraints. Influences of implant geometry and fiber aspect ratio were independent of material parameters. For a cyclic force of constant magnitude, implant thickness was directly and cross-sectional area inversely proportional to power generation potential. Fiber aspect ratios above 30 yielded maximum power generation potential while volume fractions above 15% showed superior performance. This investigation demonstrates the feasibility of using composite piezoelectric biomaterials in medical implants to generate therapeutic levels of direct current electrical stimulation. The piezoelectric spinal fusion interbody implant shows promise for helping increase success rates of spinal fusion.

  20. Mechanical and Biological Interactions of Implants with the Brain and Their Impact on Implant Design

    PubMed Central

    Prodanov, Dimiter; Delbeke, Jean

    2016-01-01

    Neural prostheses have already a long history and yet the cochlear implant remains the only success story about a longterm sensory function restoration. On the other hand, neural implants for deep brain stimulation are gaining acceptance for variety of disorders including Parkinsons disease and obsessive-compulsive disorder. It is anticipated that the progress in the field has been hampered by a combination of technological and biological factors, such as the limited understanding of the longterm behavior of implants, unreliability of devices, biocompatibility of the implants among others. While the field's understanding of the cell biology of interactions at the biotic-abiotic interface has improved, relatively little attention has been paid on the mechanical factors (stress, strain), and hence on the geometry that can modulate it. This focused review summarizes the recent progress in the understanding of the mechanisms of mechanical interaction between the implants and the brain. The review gives an overview of the factors by which the implants interact acutely and chronically with the tissue: blood-brain barrier (BBB) breach, vascular damage, micromotions, diffusion etc. We propose some design constraints to be considered in future studies. Aspects of the chronic cell-implant interaction will be discussed in view of the chronic local inflammation and the ways of modulating it. PMID:26903786

  1. Implantation in IVF.

    PubMed

    Busso, Cristiano E; Melo, Marco A B; Fernandez, Manuel; Pellicer, Antonio; Simon, Carlos

    2006-01-01

    The recent advances in assisted reproduction have made it possible to study and interfere in almost every step of the human reproductive process except for implantation. The most complex and important step remains in great part unknown. Implantation in human has proven to be less efficient compared with other species. However, in in vitro fertilization (IVF) patients, it has been evaluated to be even poorer. This paper highlights the factors related to infertile patients and IVF treatments that can affect implantation and implantation's clinical aspects related to these treatments: implantation failure and early pregnancy loss.

  2. A novel strategy for long-term implantable artificial pancreas.

    PubMed

    Ricotti, Leonardo; Assaf, Tareq; Menciassi, Arianna; Dario, Paolo

    2011-01-01

    Technology has recently changed type 1 diabetes treatment by introducing several advancements able to improve patients' quality of life. However, despite of several decades of research efforts, the dream of a fully-automated implanted artificial pancreas is quite far from its realization. The need for periodically restoring the implanted battery charge and refilling the implanted insulin reservoir are the main issues, for which invasive surgery, transcutaneous catheters or external portable devices are presently the only solutions. In this paper we propose a novel approach to these issues, describing a totally implanted closed-loop artificial pancreas with a wireless battery charger and a non-invasive strategy for insulin refilling, based on sensorized swallowable "insulin carrier" capsules. Such system has the potential to represent a final solution for diabetes treatment, by fully restoring patients' quality of life.

  3. Human pre-implantation embryo development

    PubMed Central

    Niakan, Kathy K.; Han, Jinnuo; Pedersen, Roger A.; Simon, Carlos; Pera, Renee A. Reijo

    2012-01-01

    Understanding human pre-implantation development has important implications for assisted reproductive technology (ART) and for human embryonic stem cell (hESC)-based therapies. Owing to limited resources, the cellular and molecular mechanisms governing this early stage of human development are poorly understood. Nonetheless, recent advances in non-invasive imaging techniques and molecular and genomic technologies have helped to increase our understanding of this fascinating stage of human development. Here, we summarize what is currently known about human pre-implantation embryo development and highlight how further studies of human pre-implantation embryos can be used to improve ART and to fully harness the potential of hESCs for therapeutic goals. PMID:22318624

  4. From Guided Surgery to Final Prosthesis with a Fully Digital Procedure: A Prospective Clinical Study on 15 Partially Edentulous Patients.

    PubMed

    Dolcini, Giorgio Andrea; Colombo, Marco; Mangano, Carlo

    2016-01-01

    Scope. To demonstrate guided implant placement and the application of fixed, implant-supported prosthetic restorations with a fully digital workflow. Methods. Over a 2-year period, all patients with partial edentulism of the posterior maxilla, in need of fixed implant-supported prostheses, were considered for inclusion in this study. The protocol required intraoral scanning and cone beam computed tomography (CBCT), the superimposition of dental-gingival information on bone anatomy, surgical planning, 3D-printed teeth-supported surgical templates, and modelling and milling of polymethylmethacrylate (PMMA) temporaries for immediate loading. After 3 months, final optical impression was taken and milled zirconia frameworks and 3D-printed models were fabricated. The frameworks were veneered with ceramic and delivered to the patients. Results. Fifteen patients were selected for this study. The surgical templates were stable. Thirty implants were placed (BTK Safe®, BTK, Vicenza, Italy) and immediately loaded with PMMA temporaries. After 3 months, the temporaries were replaced by the final restorations in zirconia-ceramic, fabricated with a fully digital process. At 6 months, none of the patients reported any biological or functional problems with the implant-supported prostheses. Conclusions. The present procedure for fully digital planning of implants and short-span fixed implant-supported restorations has been shown to be reliable. Further studies are needed to validate these results. PMID:27493665

  5. From Guided Surgery to Final Prosthesis with a Fully Digital Procedure: A Prospective Clinical Study on 15 Partially Edentulous Patients

    PubMed Central

    2016-01-01

    Scope. To demonstrate guided implant placement and the application of fixed, implant-supported prosthetic restorations with a fully digital workflow. Methods. Over a 2-year period, all patients with partial edentulism of the posterior maxilla, in need of fixed implant-supported prostheses, were considered for inclusion in this study. The protocol required intraoral scanning and cone beam computed tomography (CBCT), the superimposition of dental-gingival information on bone anatomy, surgical planning, 3D-printed teeth-supported surgical templates, and modelling and milling of polymethylmethacrylate (PMMA) temporaries for immediate loading. After 3 months, final optical impression was taken and milled zirconia frameworks and 3D-printed models were fabricated. The frameworks were veneered with ceramic and delivered to the patients. Results. Fifteen patients were selected for this study. The surgical templates were stable. Thirty implants were placed (BTK Safe®, BTK, Vicenza, Italy) and immediately loaded with PMMA temporaries. After 3 months, the temporaries were replaced by the final restorations in zirconia-ceramic, fabricated with a fully digital process. At 6 months, none of the patients reported any biological or functional problems with the implant-supported prostheses. Conclusions. The present procedure for fully digital planning of implants and short-span fixed implant-supported restorations has been shown to be reliable. Further studies are needed to validate these results. PMID:27493665

  6. Noninvasive techniques for probing neurocircuitry and treating illness: vagus nerve stimulation (VNS), transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS)

    PubMed Central

    George, Mark S; Aston-Jones, Gary

    2010-01-01

    Although the preceding chapters discuss much of the new knowledge of neurocircuitry of neuropsychiatric diseases, and an invasive approach to treatment, this chapter describes and reviews the noninvasive methods of testing circuit-based theories and treating neuropsychiatric diseases that do not involve implanting electrodes into the brain or on its surface. These techniques are transcranial magnetic stimulation, vagus nerve stimulation, and transcranial direct current stimulation. Two of these approaches have FDA approval as therapies. PMID:19693003

  7. 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

  8. Breast implants. A review.

    PubMed

    Van Zele, D; Heymans, O

    2004-04-01

    Breast implants have been used for about four decades for both reconstructive and aesthetic purposes. In 1963, the quality of the artificial implants was revolutionized by the introduction of the silicone gel-filled implant. Since, this modern prosthesis has gone through an evolution of change and improvement with several types of devices with many variations and styles within each class. Actually, for the last three decades, approximately one million women have received silicone breast implants in the USA. But, in 1992, the American FDA banned silicone from the market, leaving saline implants as the only product generally available as an alternative until now. Other filler materials were introduced, but have never progressed beyond the experimental stage in the USA (in contrast with Europe). The evolution of the different implants through time, with their advantages and disadvantages will be discussed, but also the controversy on silicone implants in the USA and their suspected association with systemic diseases. PMID:15154572

  9. An in vivo assessment of the effects of using different implant abutment occluding materials on implant microleakage and the peri-implant microbiome

    NASA Astrophysics Data System (ADS)

    Rubino, Caroline

    Microleakage may be a factor in the progression of peri-implant pathology. Microleakage in implant dentistry refers to the passage of bacteria, fluids, molecules or ions between the abutment-implant interface to and from the surrounding periodontal tissues. This creates a zone of inflammation and reservoir of bacteria at the implant-abutment interface. Bone loss typically occurs within the first year of abutment connection and then stabilizes. It has not yet been definitively proven that the occurrence of microleakage cannot contribute to future bone loss or impede the treatment of peri-implant disease. Therefore, strategies to reduce or eliminate microleakage are sought out. Recent evidence demonstrates that the type of implant abutment channel occluding material can affect the amount of microleakage in an in vitro study environment. Thus, we hypothesize that different abutment screw channel occluding materials will affect the amount of observed microleakage, vis-a-vis the correlation between the microflora found on the abutment screw channel occluding material those found in the peri-implant sulcus. Additional objectives include confirming the presence of microleakage in vivo and assessing any impact that different abutment screw channel occluding materials may have on the peri-implant microbiome. Finally, the present study provides an opportunity to further characterize the peri-implant microbiome. Eight fully edentulous patients restored with at dental implants supporting screw-retained fixed hybrid prostheses were included in the study. At the initial appointment (T1), the prostheses were removed and the implants and prostheses were cleaned. The prostheses were then inserted with polytetrafluoroethylene tape (PTFE, TeflonRTM), cotton, polyvinyl siloxane (PVS), or synthetic foam as the implant abutment channel occluding material and sealed over with composite resin. About six months later (T2), the prostheses were removed and the materials collected. Paper

  10. Behavioral and Electrophysiological Responses Evoked by Chronic Infrared Neural Stimulation of the Cochlea

    PubMed Central

    Matic, Agnella Izzo; Robinson, Alan M.; Young, Hunter K.; Badofsky, Ben; Rajguru, Suhrud M.; Stock, Stuart; Richter, Claus-Peter

    2013-01-01

    Infrared neural stimulation (INS) has been proposed as a novel method for neural stimulation. In order for INS to translate to clinical use, which would involve the use of implanted devices over years or decades, the efficacy and safety of chronic INS needs to be determined. We examined a population of cats that were chronically implanted with an optical fiber to stimulate the cochlea with infrared radiation, the first known chronic application of INS. Through behavioral responses, the cats demonstrate that stimulation occurs and a perceptual event results. Long-term stimulation did not result in a change in the electrophysiological responses, either optically-evoked or acoustically-evoked. Spiral ganglion neuron counts and post implantation tissue growth, which was localized at the optical fiber, were similar in chronically stimulated and sham implanted cochleae. Results from chronic INS experiments in the cat cochlea support future work toward INS-based neuroprostheses for humans. PMID:23505466

  11. Implantable imaging system for visual prosthesis.

    PubMed

    Zhou, Chuanqing; Tao, Chen; Chai, Xinyu; Sun, Yong; Ren, Qiushi

    2010-06-01

    In order to propose a method of intraocular imaging system for the visual prosthesis, an implantable microcamera was developed and evaluated in vivo. The microcamera was specially developed and shaped to fit the rabbit's lens capsule and encapsulated with the biocompatible silicone. To evaluate the feasibility of this novel approach, the custom-built device was implanted following the surgical extraction of rabbit's lens. And clinical examinations were performed 1 day, 3 days, 1 week, 2 week, and 1 month postoperatively, including slit-lamp examination, intraocular pressure, wound status, anterior chamber depth, the presence of the iris fibrosi of neovascularization, and the position of the implant. Real-time imaging was performed in vivo 1 month after the operation, and the acquired images were processed with the software and hardware that were specially developed for generating the stimulating pulses. Short-term results showed the novel approach is promising.

  12. PCB with fully integrated optical interconnects

    NASA Astrophysics Data System (ADS)

    Langer, Gregor; Satzinger, Valentin; Schmidt, Volker; Schmid, Gerhard; Leeb, Walter R.

    2011-01-01

    The increasing demand for miniaturization and design flexibility of polymer optical waveguides integrated into electrical printed circuit boards (PCB) calls for new coupling and integration concepts. We report on a method that allows the coupling of optical waveguides to electro-optical components as well as the integration of an entire optical link into the PCB. The electro-optical devices such as lasers and photodiodes are assembled on the PCB and then embedded in an optically transparent material. A focused femtosecond laser beam stimulates a polymerization reaction based on a two-photon absorption effect in the optical material and locally increases the refractive index of the material. In this way waveguide cores can be realized and the embedded components can be connected optically. This approach does not only allow a precise alignment of the waveguide end faces to the components but also offers a truly 3-dimensional routing capability of the waveguides. Using this technology we were able to realize butt-coupling and mirror-coupling interface solutions in several demonstrators. We were also manufacturing demonstrator boards with fully integrated driver and preamplifier chips, which show very low power consumption of down to 10 mW for about 2.5 Gbit/s. Furthermore, demonstrators with interconnects at two different optical layers were realized.

  13. Fully analogue photonic reservoir computer.

    PubMed

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-03-03

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers.

  14. Fully analogue photonic reservoir computer

    PubMed Central

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-01-01

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers. PMID:26935166

  15. Fully integrated, fully automated generation of short tandem repeat profiles

    PubMed Central

    2013-01-01

    Background The generation of short tandem repeat profiles, also referred to as ‘DNA typing,’ is not currently performed outside the laboratory because the process requires highly skilled technical operators and a controlled laboratory environment and infrastructure with several specialized instruments. The goal of this work was to develop a fully integrated system for the automated generation of short tandem repeat profiles from buccal swab samples, to improve forensic laboratory process flow as well as to enable short tandem repeat profile generation to be performed in police stations and in field-forward military, intelligence, and homeland security settings. Results An integrated system was developed consisting of an injection-molded microfluidic BioChipSet cassette, a ruggedized instrument, and expert system software. For each of five buccal swabs, the system purifies DNA using guanidinium-based lysis and silica binding, amplifies 15 short tandem repeat loci and the amelogenin locus, electrophoretically separates the resulting amplicons, and generates a profile. No operator processing of the samples is required, and the time from swab insertion to profile generation is 84 minutes. All required reagents are contained within the BioChipSet cassette; these consist of a lyophilized polymerase chain reaction mix and liquids for purification and electrophoretic separation. Profiles obtained from fully automated runs demonstrate that the integrated system generates concordant short tandem repeat profiles. The system exhibits single-base resolution from 100 to greater than 500 bases, with inter-run precision with a standard deviation of ±0.05 - 0.10 bases for most alleles. The reagents are stable for at least 6 months at 22°C, and the instrument has been designed and tested to Military Standard 810F for shock and vibration ruggedization. A nontechnical user can operate the system within or outside the laboratory. Conclusions The integrated system represents the

  16. Wirelessly powered, fully internal optogenetics for brain, spinal and peripheral circuits in mice.

    PubMed

    Montgomery, Kate L; Yeh, Alexander J; Ho, John S; Tsao, Vivien; Mohan Iyer, Shrivats; Grosenick, Logan; Ferenczi, Emily A; Tanabe, Yuji; Deisseroth, Karl; Delp, Scott L; Poon, Ada S Y

    2015-10-01

    To enable sophisticated optogenetic manipulation of neural circuits throughout the nervous system with limited disruption of animal behavior, light-delivery systems beyond fiber optic tethering and large, head-mounted wireless receivers are desirable. We report the development of an easy-to-construct, implantable wireless optogenetic device. Our smallest version (20 mg, 10 mm(3)) is two orders of magnitude smaller than previously reported wireless optogenetic systems, allowing the entire device to be implanted subcutaneously. With a radio-frequency (RF) power source and controller, this implant produces sufficient light power for optogenetic stimulation with minimal tissue heating (<1 °C). We show how three adaptations of the implant allow for untethered optogenetic control throughout the nervous system (brain, spinal cord and peripheral nerve endings) of behaving mice. This technology opens the door for optogenetic experiments in which animals are able to behave naturally with optogenetic manipulation of both central and peripheral targets.

  17. Technological Advances in Deep Brain Stimulation.

    PubMed

    Ughratdar, Ismail; Samuel, Michael; Ashkan, Keyoumars

    2015-01-01

    Functional and stereotactic neurosurgery has always been regarded as a subspecialty based on and driven by technological advances. However until recently, the fundamentals of deep brain stimulation (DBS) hardware and software design had largely remained stagnant since its inception almost three decades ago. Recent improved understanding of disease processes in movement disorders as well clinician and patient demands has resulted in new avenues of development for DBS technology. This review describes new advances both related to hardware and software for neuromodulation. New electrode designs with segmented contacts now enable sophisticated shaping and sculpting of the field of stimulation, potentially allowing multi-target stimulation and avoidance of side effects. To avoid lengthy programming sessions utilising multiple lead contacts, new user-friendly software allows for computational modelling and individualised directed programming. Therapy delivery is being improved with the next generation of smaller profile, longer-lasting, re-chargeable implantable pulse generators (IPGs). These include IPGs capable of delivering constant current stimulation or personalised closed-loop adaptive stimulation. Post-implantation Magnetic Resonance Imaging (MRI) has long been an issue which has been partially overcome with 'MRI conditional devices' and has enabled verification of DBS lead location. Surgical technique is considering a shift from frame-based to frameless stereotaxy or greater role for robot assisted implantation. The challenge for these contemporary techniques however, will be in demonstrating equivalent safety and accuracy to conventional methods. We also discuss potential future direction utilising wireless technology allowing for miniaturisation of hardware. PMID:26406128

  18. Technological Advances in Deep Brain Stimulation.

    PubMed

    Ughratdar, Ismail; Samuel, Michael; Ashkan, Keyoumars

    2015-01-01

    Functional and stereotactic neurosurgery has always been regarded as a subspecialty based on and driven by technological advances. However until recently, the fundamentals of deep brain stimulation (DBS) hardware and software design had largely remained stagnant since its inception almost three decades ago. Recent improved understanding of disease processes in movement disorders as well clinician and patient demands has resulted in new avenues of development for DBS technology. This review describes new advances both related to hardware and software for neuromodulation. New electrode designs with segmented contacts now enable sophisticated shaping and sculpting of the field of stimulation, potentially allowing multi-target stimulation and avoidance of side effects. To avoid lengthy programming sessions utilising multiple lead contacts, new user-friendly software allows for computational modelling and individualised directed programming. Therapy delivery is being improved with the next generation of smaller profile, longer-lasting, re-chargeable implantable pulse generators (IPGs). These include IPGs capable of delivering constant current stimulation or personalised closed-loop adaptive stimulation. Post-implantation Magnetic Resonance Imaging (MRI) has long been an issue which has been partially overcome with 'MRI conditional devices' and has enabled verification of DBS lead location. Surgical technique is considering a shift from frame-based to frameless stereotaxy or greater role for robot assisted implantation. The challenge for these contemporary techniques however, will be in demonstrating equivalent safety and accuracy to conventional methods. We also discuss potential future direction utilising wireless technology allowing for miniaturisation of hardware.

  19. 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

  20. Role of Nuclear Receptors in Blastocyst Implantation

    PubMed Central

    Vasquez, YM; DeMayo, FJ

    2013-01-01

    The regulation of blastocyst implantation in the uterus is orchestrated by the ovarian hormones estrogen and progesterone. These hormones act via their nuclear receptors to direct the transcriptional activity of the endometrial compartments and create a defined period in which the uterus is permissive to embryo implantation termed the “window of receptivity”. Additional members of the nuclear receptor family have also been described to have a potential role in endometrial function. Much of what we know about the function of these nuclear receptors during implantation we have learned from the use of mouse models. Transgenic murine models with targeted gene ablation have allowed us to identify a complex network of paracrine signaling between the endometrial epithelium and stroma. While some of the critical molecules have been identified, the mechanism underlying the intricate communication between endometrial compartments during the implantation window has not been fully elucidated. Defining this mechanism will help identify markers of a receptive uterine environment, ultimately providing a useful tool to help improve the fertility outlook for reproductively challenged couples. The aim of this review is to outline our current understanding of how nuclear receptors and their effector molecules regulate blastocyst implantation in the endometrium. PMID:23994285

  1. Electrode migration after cochlear implant surgery: more common than expected?

    PubMed

    Dietz, Aarno; Wennström, Minna; Lehtimäki, Antti; Löppönen, Heikki; Valtonen, Hannu

    2016-06-01

    The overall complication rate of cochlear implant surgery is low and so-called electrode failures (electrode migration, misplacement, etc.,) account for only a minority of all complications. The aim of this study was to explore the prevalence of electrode migration as the cause for increased impedance values and non-auditory stimulation in the basal channels. Within the scope of a quality control process, the cochlear implant database of the Kuopio University Hospital (Finland) was reviewed. Patients with gradual elevation of impedance values and/or non-auditory stimulation of the basal electrode channels were re-examined and cone-beam computed tomography was administered. There were 162 cochlear implant recipients and 201 implanted devices registered in the database. A total of 18 patients (18 devices) were identified having significantly increased impedance values or non-auditory stimulation of the basal electrodes. Cone-beam computed tomography revealed extra-cochlear electrodes in 12 of these patients due to the migration of the electrode array. All extruded electrodes were lateral wall electrodes, i.e., straight electrode arrays (Cochlear CI422 and Med-El devices). The most common feature of electrode migration was the gradual increase of the impedance values in the basal electrodes, even though telemetry could also be unsuspicious. Electrode migration after cochlear implant surgery may be more common than previously reported. At surgery, special attention should be paid to the reliable fixation of the electrode array. This study underlines the importance of postoperative imaging after cochlear implant surgery.

  2. Hearing preservation in cochlear implant surgery.

    PubMed

    Miranda, Priscila Carvalho; Sampaio, André Luiz Lopes; Lopes, Rafaela Aquino Fernandes; Ramos Venosa, Alessandra; de Oliveira, Carlos Augusto Costa Pires

    2014-01-01

    In the past, it was thought that hearing loss patients with residual low-frequency hearing would not be good candidates for cochlear implantation since insertion was expected to induce inner ear trauma. Recent advances in electrode design and surgical techniques have made the preservation of residual low-frequency hearing achievable and desirable. The importance of preserving residual low-frequency hearing cannot be underestimated in light of the added benefit of hearing in noisy atmospheres and in music quality. The concept of electrical and acoustic stimulation involves electrically stimulating the nonfunctional, high-frequency region of the cochlea with a cochlear implant and applying a hearing aid in the low-frequency range. The principle of preserving low-frequency hearing by a "soft surgery" cochlear implantation could also be useful to the population of children who might profit from regenerative hair cell therapy in the future. Main aspects of low-frequency hearing preservation surgery are discussed in this review: its brief history, electrode design, principles and advantages of electric-acoustic stimulation, surgical technique, and further implications of this new treatment possibility for hearing impaired patients. PMID:25276136

  3. Deep brain stimulation: new techniques.

    PubMed

    Hariz, Marwan

    2014-01-01

    The technology of the hardware used in deep brain stimulation (DBS), and the mode of delivering the stimulation have not significantly evolved since the start of the modern era of DBS 25 years ago. However, new technology is now being developed along several avenues. New features of the implantable pulse generator (IPG) allow fractionation of the electric current into variable proportions between different contacts of the multi-polar lead. Another design consists in leads that allow selective current steering from directionally placed electrode contacts that would deliver the stimulation in a specific direction or even create a directional shaped electric field that would conform to the anatomy of the brain target aimed at, avoiding adjacent structures, and thus avoiding side effects. Closed loop adaptive stimulation technologies are being developed, allowing a tracking of the pathological local field potential of the brain target, and delivering automatically the stimulation to suppress the pathological activity as soon as it is detected and for as long as needed. This feature may contribute to a DBS therapy "on demand", instead of continuously. Finally, advances in imaging technology are providing "new" brain targets, and increasingly allowing DBS to be performed accurately while avoiding the risks of microelectrode recording. PMID:24262179

  4. Restoration of auditory nerve synapses in cats by cochlear implants.

    PubMed

    Ryugo, D K; Kretzmer, E A; Niparko, J K

    2005-12-01

    Congenital deafness results in abnormal synaptic structure in endings of the auditory nerve. If these abnormalities persist after restoration of auditory nerve activity by a cochlear implant, the processing of time-varying signals such as speech would likely be impaired. We stimulated congenitally deaf cats for 3 months with a six-channel cochlear implant. The device used human speech-processing programs, and cats responded to environmental sounds. Auditory nerve fibers exhibited a recovery of normal synaptic structure in these cats. This rescue of synapses is attributed to a return of spike activity in the auditory nerve and may help explain cochlear implant benefits in childhood deafness. PMID:16322457

  5. The effects of bilateral electric and bimodal electric--acoustic stimulation on language development.

    PubMed

    Nittrouer, Susan; Chapman, Christopher

    2009-09-01

    There is no doubt that cochlear implants have improved the spoken language abilities of children with hearing loss, but delays persist. Consequently, it is imperative that new treatment options be explored. This study evaluated one aspect of treatment that might be modified, that having to do with bilateral implants and bimodal stimulation. A total of 58 children with at least one implant were tested at 42 months of age on four language measures spanning a continuum from basic to generative in nature. When children were grouped by the kind of stimulation they had at 42 months (one implant, bilateral implants, or bimodal stimulation), no differences across groups were observed. This was true even when groups were constrained to only children who had at least 12 months to acclimatize to their stimulation configuration. However, when children were grouped according to whether or not they had spent any time with bimodal stimulation (either consistently since their first implant or as an interlude to receiving a second) advantages were found for children who had some bimodal experience, but those advantages were restricted to language abilities that are generative in nature. Thus, previously reported benefits of simultaneous bilateral implantation early in a child's life may not extend to generative language. In fact, children may benefit from a period of bimodal stimulation early in childhood because low-frequency speech signals provide prosody and serve as an aid in learning how to perceptually organize the signal that is received through a cochlear implant. PMID:19713210

  6. The effects of bilateral electric and bimodal electric--acoustic stimulation on language development.

    PubMed

    Nittrouer, Susan; Chapman, Christopher

    2009-09-01

    There is no doubt that cochlear implants have improved the spoken language abilities of children with hearing loss, but delays persist. Consequently, it is imperative that new treatment options be explored. This study evaluated one aspect of treatment that might be modified, that having to do with bilateral implants and bimodal stimulation. A total of 58 children with at least one implant were tested at 42 months of age on four language measures spanning a continuum from basic to generative in nature. When children were grouped by the kind of stimulation they had at 42 months (one implant, bilateral implants, or bimodal stimulation), no differences across groups were observed. This was true even when groups were constrained to only children who had at least 12 months to acclimatize to their stimulation configuration. However, when children were grouped according to whether or not they had spent any time with bimodal stimulation (either consistently since their first implant or as an interlude to receiving a second) advantages were found for children who had some bimodal experience, but those advantages were restricted to language abilities that are generative in nature. Thus, previously reported benefits of simultaneous bilateral implantation early in a child's life may not extend to generative language. In fact, children may benefit from a period of bimodal stimulation early in childhood because low-frequency speech signals provide prosody and serve as an aid in learning how to perceptually organize the signal that is received through a cochlear implant.

  7. Fully automated solid weighing workstation.

    PubMed

    Wong, Stephen K-F; Lu, YiFeng; Heineman, William; Palmer, Janice; Courtney, Carter

    2005-08-01

    A fully automated, solid-to-solid weighing workstation (patent pending) is described in this article. The core of this automated process is the use of an electrostatically charged pipette tip to attract solid particles on its outside surface. The particles were then dislodged into a 1.2-mL destination vial in a microbalance by spinning the pipette tip. Textures of solid that could be weighed included powder, crystalline, liquid, and semi-solid substances. The workstation can pick up submilligram quantities of sample (=0.3mg) from source vials containing as little as 1mg. The destination vials containing the samples were stored in a 96-well rack to enable subsequent automated liquid handling. Using bovine serum albumin as test solid, the coefficient of variation of the protein concentration for 48 samples is less than 6%. The workstation was used successfully to weigh out 48 different synthetic compounds. Time required for automated weighing was similar to manual weighing. The use of this workstation reduced 90% hands-on time and thus exposure to potentially toxic compounds. In addition, it minimized sample waste and reduced artifacts due to the poor solubility of compound in solvents. Moreover, it enabled compounds synthesized in milligram quantities to be weighed out and tested in biological assays.

  8. Fully Employing Software Inspections Data

    NASA Technical Reports Server (NTRS)

    Shull, Forrest; Feldmann, Raimund L.; Seaman, Carolyn; Regardie, Myrna; Godfrey, Sally

    2009-01-01

    Software inspections provide a proven approach to quality assurance for software products of all kinds, including requirements, design, code, test plans, among others. Common to all inspections is the aim of finding and fixing defects as early as possible, and thereby providing cost savings by minimizing the amount of rework necessary later in the lifecycle. Measurement data, such as the number and type of found defects and the effort spent by the inspection team, provide not only direct feedback about the software product to the project team but are also valuable for process improvement activities. In this paper, we discuss NASA's use of software inspections and the rich set of data that has resulted. In particular, we present results from analysis of inspection data that illustrate the benefits of fully utilizing that data for process improvement at several levels. Examining such data across multiple inspections or projects allows team members to monitor and trigger cross project improvements. Such improvements may focus on the software development processes of the whole organization as well as improvements to the applied inspection process itself.

  9. Advances in functional electrical stimulation (FES).

    PubMed

    Popović, Dejan B

    2014-12-01

    This review discusses the advancements that are needed to enhance the effects of electrical stimulation for restoring or assisting movement in humans with an injury/disease of the central nervous system. A complex model of the effects of electrical stimulation of peripheral systems is presented. The model indicates that both the motor and sensory systems are activated by electrical stimulation. We propose that a hierarchical hybrid controller may be suitable for functional electrical stimulation (FES) because this type of controller acts as a structural mimetic of its biological counterpart. Specific attention is given to the neural systems at the periphery with respect to the required electrodes and stimulators. Furthermore, we note that FES with surface electrodes is preferred for the therapy, although there is a definite advantage associated with implantable technology for life-long use. The last section of the review discusses the potential need to combine FES and robotic systems to provide assistance in some cases. PMID:25287528

  10. 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.

  11. Implants in adolescents

    PubMed Central

    Shah, Rohit A.; Mitra, Dipika K.; Rodrigues, Silvia V.; Pathare, Pragalbha N.; Podar, Rajesh S.; Vijayakar, Harshad N.

    2013-01-01

    Implants have gained tremendous popularity as a treatment modality for replacement of missing teeth in adults. There is extensive research present on the use of implants in adults, but there is a dearth of data available on the same in adolescents. The treatment planning and execution of implant placement in adolescents is still in its infancy. This review article is an attempt to bring together available literature. PMID:24174743

  12. Electrodeposited silk coatings for functionalized implant applications

    NASA Astrophysics Data System (ADS)

    Elia, Roberto

    modulated over a 10-fold range and implant insertion into bone mimics demonstrated that the coatings were able to withstand delamination forces experienced during these mock implantations. Antibiotic release from coated implant studs inhibited bacterial growth and dexamethasone release was shown to stimulate calcium deposition in mesenchymal stem cells.

  13. Implantable cardioverter defibrillator - discharge

    MedlinePlus

    Baddour LM, Epstein AE, Erickson CC, et al. Update on cardiovascular implantable electronic device infections and their management: a scientific statement from the American Heart Association. Circulation . ...

  14. A New Classification for the Relationship between Periodontal, Periapical, and Peri-implant Complications

    PubMed Central

    Kadkhodazadeh, Mahdi; Amid, Reza

    2013-01-01

    Introduction There are numerous studies supporting the high success rate of dental implants used for reconstruction of missing teeth. However, complications like mucositis and peri-implantitis are increasingly reported. Placement of dental implants in partially edentulous patients is associated with the risk of peri-implant diseases, especially when an old or a new inflammatory lesion is present adjacent to the implant site. Although no consensus has been reached on the difference in prevalence of peri-implant mucositis and peri-implantitis between fully and partially edentulous patients, available data clearly show that the combination of periodontal lesion and peri-implantitis is a possible risk factor for further complications. Several classification systems have been suggested for determination of the severity of disease around dental implants. However, no classification has been proposed for combined biological complications around teeth and implants. This study reviews the possible pathologic communication routes between natural dentition and the implants installed adjacent to them. Furthermore, we introduce a new classification system for the peri-implant disease in association with natural teeth called “PIST”. This system was designed based on the origin of the defects in order to clarify the different pathological situations which can be detected around dental implant. Using this classification system can help improve diagnosis, comparison and subsequent selection of the best treatment option. PMID:23922570

  15. Objective intraoperative method to record averaged electromyographic stapedius muscle reflexes in cochlear implant patients.

    PubMed

    Almqvist, B; Harris, S; Shallop, J K

    2000-01-01

    We have developed a procedure to measure the averaged stapedius muscle reflex in response to electrical stimulation (AESR) with a cochlear implant. The AESR, as activated by ipsilateral stimulation with a cochlear implant, was investigated intra-operatively in a series of 12 children. After the cochlear implant was placed into the cochlea and secured by the surgeon, an electromyographic (EMG) needle electrode was gently placed into the stapedius muscle. During stimulation of the cochlear implant, the stapedius reflex was monitored visually (VESR) and as an averaged EMG response (AESR). Consistent AESRs were obtained in 7 of the 12 children. These measures provide a method to obtain stapedius muscle responses that may be helpful in the programming of young children with cochlear implants. Comparative post-operative measures were also obtained, including behavioral threshold levels, behavioral comfort levels, and the contralateral stapedius reflex threshold (ESR) on selected electrodes.

  16. MED-EL Cochlear Implants: State of the Art and a Glimpse Into the Future

    PubMed Central

    Hochmair, Ingeborg; Nopp, Peter; Jolly, Claude; Schmidt, Marcus; Schößer, Hansjörg; Garnham, Carolyn; Anderson, Ilona

    2006-01-01

    Cochlear implantation is an accepted treatment method for adults and children with severe to profound hearing loss. Confidence in technology has led to changes in individuals who can receive a cochlear implant and changes in expected benefit with a cochlear implant. This article describes the research and development activities at MED-EL, which make possible the implementation of new speech-coding strategies as well as the application of acoustic and electric stimulation via a combined speech processor in MED-EL devices. Research on benefits from bilateral cochlear implantation and electric-acoustic stimulation are also reviewed. Finally, the potential of drug delivery systems is considered as a way to improve cochlear implant outcomes, and results from preliminary evaluations of a hybrid cochlear implant system with drug delivery capabilities are reported. PMID:17172548

  17. Spatial Channel Interactions in Cochlear Implants

    PubMed Central

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

    2011-01-01

    The modern multi-channel cochlear implant is widely considered to be the most successful neural prosthesis for 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 5 modern cochlear implant subjects. The physical interaction was examined using an electric field imaging technique, which measured voltage distribution as a function of electrode position in the cochlea in response to stimulation of a single electrode. The physiological interaction was examined by recording electrically evoked compound action potentials as a function of electrode position in response to 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 lower in all measures. 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 wider half-width and shallower slope than the basal side. On the contrary, the evoked

  18. Spatial channel interactions in cochlear implants.

    PubMed

    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

  19. 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

  20. Peripheral neural activity recording and stimulation system.

    PubMed

    Loi, D; Carboni, C; Angius, G; Angotzi, G N; Barbaro, M; Raffo, L; Raspopovic, S; Navarro, X

    2011-08-01

    This paper presents a portable, embedded, microcontroller-based system for bidirectional communication (recording and stimulation) between an electrode, implanted in the peripheral nervous system, and a host computer. The device is able to record and digitize spontaneous and/or evoked neural activities and store them in data files on a PC. In addition, the system has the capability of providing electrical stimulation of peripheral nerves, injecting biphasic current pulses with programmable duration, intensity, and frequency. The recording system provides a highly selective band-pass filter from 800 Hz to 3 kHz, with a gain of 56 dB. The amplification range can be further extended to 96 dB with a variable gain amplifier. The proposed acquisition/stimulation circuitry has been successfully tested through in vivo measurements, implanting a tf-LIFE electrode in the sciatic nerve of a rat. Once implanted, the device showed an input referred noise of 0.83 μVrms, was capable of recording signals below 10 μ V, and generated muscle responses to injected stimuli. The results demonstrate the capability of processing and transmitting neural signals with very low distortion and with a power consumption lower than 1 W. A graphic, user-friendly interface has been developed to facilitate the configuration of the entire system, providing the possibility to activate stimulation and monitor recordings in real time.

  1. Fully transparent and rollable electronics.

    PubMed

    Mativenga, Mallory; Geng, Di; Kim, Byungsoon; Jang, Jin

    2015-01-28

    Major obstacles toward the manufacture of transparent and flexible display screens include the difficulty of finding transparent and flexible semiconductors and electrodes, temperature restrictions of flexible plastic substrates, and bulging or warping of the flexible electronics during processing. Here we report the fabrication and performance of fully transparent and rollable thin-film transistor (TFT) circuits for display applications. The TFTs employ an amorphous indium-gallium-zinc oxide semiconductor (with optical band gap of 3.1 eV) and amorphous indium-zinc oxide transparent conductive electrodes, and are built on 15-μm-thick solution-processed colorless polyimide (CPI), resulting in optical transmittance >70% in the visible range. As the CPI supports processing temperatures >300 °C, TFT performance on plastic is similar to that on glass, with typical field-effect mobility, turn-on voltage, and subthreshold voltage swing of 12.7 ± 0.5 cm(2)/V·s, -1.7 ± 0.2 V, and 160 ± 29 mV/dec, respectively. There is no significant degradation after rolling the TFTs 100 times on a cylinder with a radius of 4 mm or when shift registers, each consisting of 40 TFTs, are operated while bent to a radius of 2 mm. For handling purposes, carrier glass is used during fabrication, together with a very thin (∼1 nm) solution-processed carbon nanotube (CNT)/graphene oxide (GO) backbone that is first spin-coated on the glass to decrease adhesion of the CPI to the glass; peel strength of the CPI from glass decreases from 0.43 to 0.10 N/cm, which eases the process of detachment performed after device fabrication. Given that the CNT/GO remains embedded under the CPI after detachment, it minimizes wrinkling and decreases the substrate's tensile elongation from 8.0% to 4.6%. Device performance is also stable under electrostatic discharge exposures up to 10 kV, as electrostatic charge can be released via the conducting CNTs. PMID:25526282

  2. Spinal cord stimulation for treatment of failed back surgery syndrome--two case reports.

    PubMed

    Vijayan, R; Ahmad, T S

    1999-12-01

    Severe, persistent back pain following back surgery is often referred to as Failed Back Surgery Syndrome (FBSS). Conservative measures such as physiotherapy, back strengthening exercises, transcutaneous electrical nerve stimulation and epidural steroids may be inadequate to alleviate pain. Spinal Cord Stimulators were implanted into two patients suffering from FBSS. Both patients responded successfully to spinal cord stimulation with reduction of pain and disability.

  3. Understanding music with cochlear implants.

    PubMed

    Bruns, Lisa; Mürbe, Dirk; Hahne, Anja

    2016-01-01

    Direct stimulation of the auditory nerve via a Cochlear Implant (CI) enables profoundly hearing-impaired people to perceive sounds. Many CI users find language comprehension satisfactory, but music perception is generally considered difficult. However, music contains different dimensions which might be accessible in different ways. We aimed to highlight three main dimensions of music processing in CI users which rely on different processing mechanisms: (1) musical discrimination abilities, (2) access to meaning in music, and (3) subjective music appreciation. All three dimensions were investigated in two CI user groups (post- and prelingually deafened CI users, all implanted as adults) and a matched normal hearing control group. The meaning of music was studied by using event-related potentials (with the N400 component as marker) during a music-word priming task while music appreciation was gathered by a questionnaire. The results reveal a double dissociation between the three dimensions of music processing. Despite impaired discrimination abilities of both CI user groups compared to the control group, appreciation was reduced only in postlingual CI users. While musical meaning processing was restorable in postlingual CI users, as shown by a N400 effect, data of prelingual CI users lack the N400 effect and indicate previous dysfunctional concept building. PMID:27558546

  4. Understanding music with cochlear implants

    PubMed Central

    Bruns, Lisa; Mürbe, Dirk; Hahne, Anja

    2016-01-01

    Direct stimulation of the auditory nerve via a Cochlear Implant (CI) enables profoundly hearing-impaired people to perceive sounds. Many CI users find language comprehension satisfactory, but music perception is generally considered difficult. However, music contains different dimensions which might be accessible in different ways. We aimed to highlight three main dimensions of music processing in CI users which rely on different processing mechanisms: (1) musical discrimination abilities, (2) access to meaning in music, and (3) subjective music appreciation. All three dimensions were investigated in two CI user groups (post- and prelingually deafened CI users, all implanted as adults) and a matched normal hearing control group. The meaning of music was studied by using event-related potentials (with the N400 component as marker) during a music-word priming task while music appreciation was gathered by a questionnaire. The results reveal a double dissociation between the three dimensions of music processing. Despite impaired discrimination abilities of both CI user groups compared to the control group, appreciation was reduced only in postlingual CI users. While musical meaning processing was restorable in postlingual CI users, as shown by a N400 effect, data of prelingual CI users lack the N400 effect and indicate previous dysfunctional concept building. PMID:27558546

  5. Batteryless implanted echosonometer

    NASA Technical Reports Server (NTRS)

    Kojima, G. K.

    1977-01-01

    Miniature ultrasonic echosonometer implanted within laboratory animals obtains energy from RF power oscillator that is electronically transduced via induction loop to power receiving loop located just under animal's skin. Method of powering device offers significant advantages over those in which battery is part of implanted package.

  6. Implantable, Ingestible Electronic Thermometer

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard

    1987-01-01

    Small quartz-crystal-controlled oscillator swallowed or surgically implanted provides continuous monitoring of patient's internal temperature. Receiver placed near patient measures oscillator frequency, and temperature inferred from previously determined variation of frequency with temperature. Frequency of crystal-controlled oscillator varies with temperature. Circuit made very small and implanted or ingested to measure internal body temperature.

  7. Retinal prostheses: progress toward the next generation implants

    PubMed Central

    Ghezzi, Diego

    2015-01-01

    In the last decade, various clinical trials proved the capability of visual prostheses, in particular retinal implants, to restore a useful form of vision. These encouraging results promoted the emerging of several strategies for neuronal stimulation aiming at the restoration of sight. Besides the traditional approach based on electrical stimulation through metal electrodes in the different areas of the visual path (e.g., the visual cortex, the lateral geniculate nucleus, the optic nerve, and the retina), novel concepts for neuronal stimulation have been mostly exploited as building blocks of the next generation of retinal implants. This review is focused on critically discussing recent major advancements in the field of retinal stimulation with particular attention to the findings in the application of novel concepts and materials. Last, the major challenges in the field and their clinical implications will be outlined. PMID:26347602

  8. Graphene for Biomedical Implants

    NASA Astrophysics Data System (ADS)

    Moore, Thomas; Podila, Ramakrishna; Alexis, Frank; Rao, Apparao; Clemson Bioengineering Team; Clemson Physics Team

    2013-03-01

    In this study, we used graphene, a one-atom thick sheet of carbon atoms, to modify the surfaces of existing implant materials to enhance both bio- and hemo-compatibility. This novel effort meets all functional criteria for a biomedical implant coating as it is chemically inert, atomically smooth and highly durable, with the potential for greatly enhancing the effectiveness of such implants. Specifically, graphene coatings on nitinol, a widely used implant and stent material, showed that graphene coated nitinol (Gr-NiTi) supports excellent smooth muscle and endothelial cell growth leading to better cell proliferation. We further determined that the serum albumin adsorption on Gr-NiTi is greater than that of fibrinogen, an important and well understood criterion for promoting a lower thrombosis rate. These hemo-and biocompatible properties and associated charge transfer mechanisms, along with high strength, chemical inertness and durability give graphene an edge over most antithrombogenic coatings for biomedical implants and devices.

  9. Rapid thermal annealing of Si 1- xGe x layers formed by germanium ion implantation

    NASA Astrophysics Data System (ADS)

    Xia, Z.; Saarilahti, J.; Ronkainen, H.; Eränen, S.; Suni, I.; Molarius, J.; Kuivalainen, P.; Ristolainen, E.; Tuomi, T.

    1994-05-01

    (100) Si samples, amorphized by implanting with 50, 70 and 100 keV 74Ge + ions at doses of the order of 1 × 10 16cm -2, have been recrystallized by rapid thermal annealing (RTA) with different temperature-time ( T- t) combinations. Monte Carlo calculations using TRIM-91 computer program were performed to estimate the depth of amorphized regions, implanted Ge distributions and recoil-implanted O depth profiles. The RBS channeling measurements show that fully epitaxial regrowth of implanted layers can be reached with proper rapid thermal processing. An empirical guide is presented for regrowing the implanted SiGe layers with RTA. The recoil-implanted oxygen in the implanted layers was measured by 16O(α,α) 16O RBS resonance channeling and SIMS.

  10. Effect of low-frequency electrical stimulation parameters on its anticonvulsant action during rapid perforant path kindling in rat.

    PubMed

    Shahpari, Marzieh; Mirnajafi-Zadeh, Javad; Firoozabadi, Seyed Mohammad P; Yadollahpour, Ali

    2012-03-01

    Low frequency stimulation (LFS) may be considered as a new potential therapy for drug-resistant epilepsy. However, the relation between LFS parameters and its anticonvulsant effects is not completely determined. In this study, the effect of some LFS parameters on its anticonvulsant action was investigated in rats. In all animals, stimulating and recording electrodes were implanted into the perforant path and dentate gyrus, respectively. In one group of animals, kindling stimulations were applied until rats achieved a fully kindled state. In other groups, different patterns of LFS were applied at the end of kindling stimulations during twenty consecutive days. In the first experiment the effect of LFS pulse numbers was investigated on its anticonvulsant action. Animals were divided randomly into three groups and 1, 4, and 8 packages of LFS (each pack contains 200 pulses, 0.1 ms pulse duration at 1 Hz) were applied five minutes after termination of kindling stimulations. Obtained results showed that 4 packages of LFS had the strongest anticonvulsant effects. Therefore, this pattern (4 packages) was used in the next experiment. In the second experiment, 4 packages of LFS were applied at intervals of 30 s and 30 min after termination of kindling stimulations. The strongest anticonvulsant effect was observed in the group received LFS at the interval of 30 s. Therefore, this pattern was selected for the third experiment. In the third experiment the effect of LFS at frequencies of 0.25 Hz and 5 Hz was investigated. The group of animals which received LFS at the frequency of 0.25 Hz showed somehow stronger anticonvulsant effect. The results indicate that different parameters of LFS have important role in induction of LFS anticonvulsant effects. Regarding this view, it seems that the slower LFS frequency and the shorter interval between LFS and kindling stimulations, the stronger anticonvulsant effect will be observed. But there is no direct relation between number of

  11. Vagus nerve stimulation does not affect spatial memory in fast rats, but has both anti-convulsive and pro-convulsive effects on amygdala-kindled seizures.

    PubMed

    Dedeurwaerdere, S; Gilby, K; Vonck, K; Delbeke, J; Boon, P; McIntyre, D

    2006-07-21

    Vagus nerve stimulation (VNS) is an adjunctive treatment for refractory epilepsy. Using a seizure-prone Fast-kindling rat strain with known comorbid behavioral features, we investigated the effects of VNS on spatial memory, epileptogenesis, kindled seizures and body weight. Electrodes were implanted in both amygdalae and around the left vagus nerve of 17 rats. Following recovery, rats were tested in the Morris water-maze utilizing a fixed platform paradigm. The VNS group received 2 h of stimulation prior to entering the Morris water-maze. Rats were then tested in the kindling paradigm wherein the VNS group received 2 h of stimulation prior to daily kindling stimulation. Finally, the abortive effects of acute VNS against kindling-induced seizures were determined in fully kindled rats by applying VNS immediately after the kindling pulse. Body weight, water consumption and food intake were measured throughout. Memory performance in the Morris water-maze was not different between control and vagus nerve stimulation rats. Similarly, kindling rate was unaffected by antecedent VNS. However, pro-convulsive effects (P<0.05) were noted, when VNS was administered prior to the kindling pulse in fully kindled rats. Yet, paradoxically, VNS showed anti-convulsant effects (P<0.01) in those rats when applied immediately after the kindling stimulus. Body weight was significantly lower throughout kindling (P<0.01) in VNS-treated rats compared with controls, which was associated with reduced food intake (P<0.05), but without difference in water consumption. VNS appears to be devoid of significant cognitive side effects in the Morris water-maze in Fast rats. Although VNS exhibited no prophylactic effect on epileptogenesis or seizure severity when applied prior to the kindling stimulus, it showed significant anti-convulsant effects in fully kindled rats when applied after seizure initiation. Lastly, VNS prevented the weight gain associated with kindling through reduced food intake.

  12. Implanted neural interfaces: biochallenges and engineered solutions.

    PubMed

    Grill, Warren M; Norman, Sharon E; Bellamkonda, Ravi V

    2009-01-01

    Neural interfaces are connections that enable two-way exchange of information with the nervous system. These connections can occur at multiple levels, including with peripheral nerves, with the spinal cord, or with the brain; in many instances, fundamental biophysical and biological challenges are shared across these levels. We review these challenges, including selectivity, stability, resolution versus invasiveness, implant-induced injury, and the host-interface response. Subsequently, we review the engineered solutions to these challenges, including electrode designs and geometry, stimulation waveforms, materials, and surface modifications. Finally, we consider emerging opportunities to improve neural interfaces, including cellular-level silicon to neuron connections, optical stimulation, and approaches to control inflammation. Overcoming the biophysical and biological challenges will enable effective high-density neural interfaces for stimulation and recording.

  13. Protocol for Bone Augmentation with Simultaneous Early Implant Placement: A Retrospective Multicenter Clinical Study.

    PubMed

    Fairbairn, Peter; Leventis, Minas

    2015-01-01

    Purpose. To present a novel protocol for alveolar bone regeneration in parallel to early implant placement. Methods. 497 patients in need of extraction and early implant placement with simultaneous bone augmentation were treated in a period of 10 years. In all patients the same specific method was followed and grafting was performed utilizing in situ hardening fully resorbable alloplastic grafting materials consisting of β-tricalcium phosphate and calcium sulfate. The protocol involved atraumatic extraction, implant placement after 4 weeks with simultaneous bone augmentation, and loading of the implant 12 weeks after placement and grafting. Follow-up periods ranged from 6 months to 10 years (mean of 4 years). Results. A total of 601 postextraction sites were rehabilitated in 497 patients utilizing the novel protocol. Three implants failed before loading and three implants failed one year after loading, leaving an overall survival rate of 99.0%. Conclusions. This standardized protocol allows successful long-term functional results regarding alveolar bone regeneration and implant rehabilitation. The concept of placing the implant 4 weeks after extraction, augmenting the bone around the implant utilizing fully resorbable, biomechanically stable, alloplastic materials, and loading the implant at 12 weeks seems to offer advantages when compared with traditional treatment modalities. PMID:26858757

  14. Protocol for Bone Augmentation with Simultaneous Early Implant Placement: A Retrospective Multicenter Clinical Study.

    PubMed

    Fairbairn, Peter; Leventis, Minas

    2015-01-01

    Purpose. To present a novel protocol for alveolar bone regeneration in parallel to early implant placement. Methods. 497 patients in need of extraction and early implant placement with simultaneous bone augmentation were treated in a period of 10 years. In all patients the same specific method was followed and grafting was performed utilizing in situ hardening fully resorbable alloplastic grafting materials consisting of β-tricalcium phosphate and calcium sulfate. The protocol involved atraumatic extraction, implant placement after 4 weeks with simultaneous bone augmentation, and loading of the implant 12 weeks after placement and grafting. Follow-up periods ranged from 6 months to 10 years (mean of 4 years). Results. A total of 601 postextraction sites were rehabilitated in 497 patients utilizing the novel protocol. Three implants failed before loading and three implants failed one year after loading, leaving an overall survival rate of 99.0%. Conclusions. This standardized protocol allows successful long-term functional results regarding alveolar bone regeneration and implant rehabilitation. The concept of placing the implant 4 weeks after extraction, augmenting the bone around the implant utilizing fully resorbable, biomechanically stable, alloplastic materials, and loading the implant at 12 weeks seems to offer advantages when compared with traditional treatment modalities.

  15. Protocol for Bone Augmentation with Simultaneous Early Implant Placement: A Retrospective Multicenter Clinical Study

    PubMed Central

    2015-01-01

    Purpose. To present a novel protocol for alveolar bone regeneration in parallel to early implant placement. Methods. 497 patients in need of extraction and early implant placement with simultaneous bone augmentation were treated in a period of 10 years. In all patients the same specific method was followed and grafting was performed utilizing in situ hardening fully resorbable alloplastic grafting materials consisting of β-tricalcium phosphate and calcium sulfate. The protocol involved atraumatic extraction, implant placement after 4 weeks with simultaneous bone augmentation, and loading of the implant 12 weeks after placement and grafting. Follow-up periods ranged from 6 months to 10 years (mean of 4 years). Results. A total of 601 postextraction sites were rehabilitated in 497 patients utilizing the novel protocol. Three implants failed before loading and three implants failed one year after loading, leaving an overall survival rate of 99.0%. Conclusions. This standardized protocol allows successful long-term functional results regarding alveolar bone regeneration and implant rehabilitation. The concept of placing the implant 4 weeks after extraction, augmenting the bone around the implant utilizing fully resorbable, biomechanically stable, alloplastic materials, and loading the implant at 12 weeks seems to offer advantages when compared with traditional treatment modalities. PMID:26858757

  16. Suppression and facilitation of auditory neurons through coordinated acoustic and midbrain stimulation: investigating a deep brain stimulator for tinnitus

    NASA Astrophysics Data System (ADS)

    Offutt, Sarah J.; Ryan, Kellie J.; Konop, Alexander E.; Lim, Hubert H.

    2014-12-01

    Objective. The inferior colliculus (IC) is the primary processing center of auditory information in the midbrain and is one site of tinnitus-related activity. One potential option for suppressing the tinnitus percept is through deep brain stimulation via the auditory midbrain implant (AMI), which is designed for hearing restoration and is already being implanted in deaf patients who also have tinnitus. However, to assess the feasibility of AMI stimulation for tinnitus treatment we first need to characterize the functional connectivity within the IC. Previous studies have suggested modulatory projections from the dorsal cortex of the IC (ICD) to the central nucleus of the IC (ICC), though the functional properties of these projections need to be determined. Approach. In this study, we investigated the effects of electrical stimulation of the ICD on acoustic-driven activity within the ICC in ketamine-anesthetized guinea pigs. Main Results. We observed ICD stimulation induces both suppressive and facilitatory changes across ICC that can occur immediately during stimulation and remain after stimulation. Additionally, ICD stimulation paired with broadband noise stimulation at a specific delay can induce greater suppressive than facilitatory effects, especially when stimulating in more rostral and medial ICD locations. Significance. These findings demonstrate that ICD stimulation can induce specific types of plastic changes in ICC activity, which may be relevant for treating tinnitus. By using the AMI with electrode sites positioned with the ICD and the ICC, the modulatory effects of ICD stimulation can be tested directly in tinnitus patients.

  17. [Late consequences of an early stimulation of the lateral hypothalamus on the acquisition and extinction of alimentary conditioning].

    PubMed

    Velley, L; Cardo, B

    1976-04-26

    Male Sprague Dawley rats received at 13 days of age bilaterally implanted electrodes in lateral hypothalamus. At 15th and 16th days of age they underwent a total of 4 hrs imposed stimulation, according to a self-stimulation model of a 15 days animal. Electrodes were removed on the 17th day. Between the 42nd and 46th days, animals were tested in a skinnerian, alimentary reinforced task. In acquisition as well as in extinction behavior, early stimulated animals performed better than animals of the same age, implanted but non stimulated or non implanted.

  18. A microwave powered injectable neural stimulator.

    PubMed

    Towe, Bruce C; Larson, Patrick J; Gulick, Daniel W

    2012-01-01

    An unexpectedly simple implantable device that can achieve wireless neurostimulation consists of a short 1 cm long dipole platinum wire antenna, a Schottky diode, and a pulsed microwave transmitter. Fabricated into a 1 cm long by polyimide tubing, the implant can have a sub-millimeter diameter form factor suited to introduction into tissue by injection. Experiments that chronically implant the device next to a rat sciatic nerve show that a 915 MHz microwave transmitter emitting an average power of 0.5 watts has an ability to stimulate motor events when spaced up to 7 cm from the body surface. Tissue models consisting of saline filled tanks show the possibility of delivering milliampere pulsed current to neurosimulators though 5 centimeters or more of tissue. Such a neurostimulation system driven by microwave energy is limited in functional tissue depth by microwave SAR exposure. This report discusses some of the advantages and limitations of such a neurostimulation approach. PMID:23367052

  19. Dental Implant Systems

    PubMed Central

    Oshida, Yoshiki; Tuna, Elif B.; Aktören, Oya; Gençay, Koray

    2010-01-01

    Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities. PMID:20480036

  20. [Electrophysiologic and other objective tests in pediatric cochlear implantation].

    PubMed

    Bordure, P; O'Donoghue, G M; Mason, S

    1996-01-01

    Various electrophysiological procedures have been developed and utilized in pediatric cochlear implant patients. During surgery and just before implantation, recording of Electrically-Evoked Auditory Brainstem Responses (EABR) by electrical stimulation via a promontory needle electrode is a useful tool to select the suitable ear for implantation in the absence of other criteria. After implantation, peroperative assessment of the Electrically-Evoked Stapedius Reflex thresholds allows an estimation of the comfort levels not to be exceeded during the first tuning sessions. Recording of Averaged Electrode Voltages (AEV) provides assurance against general device failure, and can localize defectives electrodes which will be disactivated. Finally EABR obtained by electrical stimulation via the implant is the last control showing objective auditory responses. Furthermore there is a strong correlation between EABR thresholds and behavioral thresholds which will be obtained during the first tuning session. When a device malfunction is suspected after implantation, recording of AEV and EABR are performed, and the results are compared with the preoperative data.

  1. Approaches to USJ Formation Beyond Molecular Implantation

    SciTech Connect

    Hatem, C.; Renau, A.; Godet, L.; Kontos, A.; Papasouliotis, G.; England, J.; Arevalo, E.

    2008-11-03

    As junction depth requirements approach sub 10 nm and the sensitivity to residual implant damage continues to increase, the capability to produce abrupt, shallow profiles while maintaining low residual damage becomes a difficult challenge. Implantation induced amorphization has been widely applied to reduce channeling tails of implanted dopant profiles for integrated circuit manufacturing. This has been required to meet aggressive junction depth targets. The problem, however, is that pre-amorphization creates high defect densities that remain near the former amorphous-crystalline interface post anneal. These end of range (EOR) defects become of greater concern as the industry begins to move towards millisecond anneal technologies. Millisecond anneal, while capable of close to diffusionless activation and abrupt junctions, has caused concern for its inability to fully repair these EOR defects. There has been a recent focus on removing traditional PAI through molecular implantation with limited success. Towards this end we have investigated alternative techniques to reduce EOR damage while maintaining the junction depth, sheet resistance and abruptness. Here we describe the results of two of these techniques. The subsequent reduction in EOR through the use of each process and the resultant Rs, junction depth and abruptness are detailed.

  2. The Custom Endosteal Implant: histology and case report of a retrieved maxillary custom osseous-integrated implant nine years in service.

    PubMed

    Nordquist, William D; Krutchkoff, David J

    2014-04-01

    The Custom Endosteal Implant (CEI) is a custom-cast osseo-integrated implant that has evolved to replace the "old" fibro-integrated subperiosteal variant. This newly developed implant achieves osseous integration by utilizing a hydroxyapatite (HA) coating, and a specialized grafting technique that produces much improved success rates relative to its fibro-integrated subperiosteal predecessor. This case reported here represents a maxillary CEI implant that was placed and in functional service for 9 years before being retrieved and processed for histologic examination subsequent to the patient's demise. In addition, due to infection that occurred shortly after placement, an early provisional procedure with fluoridated HA was also performed. Histologic analysis of the postmortem specimen revealed a fully integrated new bone formation intimately surrounding the previously dehisced implant strut. The latter had previously been decontaminated and grafted with a thin layer of fluorapatite (FA) material. Results including histologic analysis confirmed complete osseo-integration of the implant following successful FA graft revision.

  3. Electroencephalographic responses to intraoperative subthalamic stimulation.

    PubMed

    Colloca, Luana; Benedetti, Fabrizio; Bergamasco, Bruno; Vighetti, Sergio; Zibetti, Maurizio; Ducati, Alessandro; Lanotte, Michele; Lopiano, Leonardo

    2006-10-01

    This study reports the effects of intraoperative stimulation of the subthalamic nucleus on brain electrical activity in advanced Parkinson's patients. To our knowledge, this is the first study about electroencephalographic responses in the very early phase of deep brain stimulation, during the implantation of the electrodes. We found an increase of gamma band bilaterally over the sensorimotor cortex in the range 45-55 Hz, which was associated with clinical improvement as assessed by means of muscle rigidity decrease. These results indicate that the electroencephalographic gamma responses to deep brain stimulation are present at the very beginning of the treatment process, and may help better understand the short and long-tem effects of deep brain stimulation.

  4. Nanotechnology for dental implants.

    PubMed

    Tomsia, Antoni P; Lee, Janice S; Wegst, Ulrike G K; Saiz, Eduardo

    2013-01-01

    With the advent of nanotechnology, an opportunity exists for the engineering of new dental implant materials. Metallic dental implants have been successfully used for decades, but they have shortcomings related to osseointegration and mechanical properties that do not match those of bone. Absent the development of an entirely new class of materials, faster osseointegration of currently available dental implants can be accomplished by various surface modifications. To date, there is no consensus regarding the preferred method(s) of implant surface modification, and further development will be required before the ideal implant surface can be created, let alone become available for clinical use. Current approaches can generally be categorized into three areas: ceramic coatings, surface functionalization, and patterning on the micro- to nanoscale. The distinctions among these are imprecise, as some or all of these approaches can be combined to improve in vivo implant performance. These surface improvements have resulted in durable implants with a high percentage of success and long-term function. Nanotechnology has provided another set of opportunities for the manipulation of implant surfaces in its capacity to mimic the surface topography formed by extracellular matrix components of natural tissue. The possibilities introduced by nanotechnology now permit the tailoring of implant chemistry and structure with an unprecedented degree of control. For the first time, tools are available that can be used to manipulate the physicochemical environment and monitor key cellular events at the molecular level. These new tools and capabilities will result in faster bone formation, reduced healing time, and rapid recovery to function.

  5. Towards a Switched-Capacitor based Stimulator for efficient deep-brain stimulation.

    PubMed

    Vidal, Jose; Ghovanloo, Maysam

    2010-01-01

    We have developed a novel 4-channel prototype stimulation circuit for implantable neurological stimulators (INS). This Switched-Capacitor based Stimulator (SCS) aims to utilize charge storage and charge injection techniques to take advantage of both the efficiency of conventional voltage-controlled stimulators (VCS) and the safety and controllability of current-controlled stimulators (CCS). The discrete SCS prototype offers fine control over stimulation parameters such as voltage, current, pulse width, frequency, and active electrode channel via a LabVIEW graphical user interface (GUI) when connected to a PC through USB. Furthermore, the prototype utilizes a floating current sensor to provide charge-balanced biphasic stimulation and ensure safety. The stimulator was analyzed using an electrode-electrolyte interface (EEI) model as well as with a pair of pacing electrodes in saline. The primary motivation of this research is to test the feasibility and functionality of a safe, effective, and power-efficient switched-capacitor based stimulator for use in Deep Brain Stimulation. PMID:21095987

  6. Towards a Switched-Capacitor Based Stimulator for Efficient Deep-Brain Stimulation

    PubMed Central

    Vidal, Jose; Ghovanloo, Maysam

    2013-01-01

    We have developed a novel 4-channel prototype stimulation circuit for implantable neurological stimulators (INS). This Switched-Capacitor based Stimulator (SCS) aims to utilize charge storage and charge injection techniques to take advantage of both the efficiency of conventional voltage-controlled stimulators (VCS) and the safety and controllability of current-controlled stimulators (CCS). The discrete SCS prototype offers fine control over stimulation parameters such as voltage, current, pulse width, frequency, and active electrode channel via a LabVIEW graphical user interface (GUI) when connected to a PC through USB. Furthermore, the prototype utilizes a floating current sensor to provide charge-balanced biphasic stimulation and ensure safety. The stimulator was analyzed using an electrode-electrolyte interface (EEI) model as well as with a pair of pacing electrodes in saline. The primary motivation of this research is to test the feasibility and functionality of a safe, effective, and power-efficient switched-capacitor based stimulator for use in Deep Brain Stimulation. PMID:21095987

  7. Reflections on Rodent Implantation.

    PubMed

    Cha, Jeeyeon M; Dey, Sudhansu K

    2015-01-01

    Embryo implantation is a complex process involving endocrine, paracrine, autocrine, and juxtacrine modulators that span cell-cell and cell-matrix interactions. The quality of implantation is predictive for pregnancy success. Earlier observational studies formed the basis for genetic and molecular approaches that ensued with emerging technological advances. However, the precise sequence and details of the molecular interactions involved have yet to be defined. This review reflects briefly on aspects of our current understanding of rodent implantation as a tribute to Roger Short's lifelong contributions to the field of reproductive physiology. PMID:26450495

  8. Spectroscopy of implants

    NASA Astrophysics Data System (ADS)

    Afanasyeva, Natalia I.

    1994-01-01

    The spectral criteria of selection of soft intraocular lens (IOL) implants of long service in an organism have been defined for ophthalmology. The analysis of Fourier Transform Infrared (FTIR) spectra provides the required and sufficient level of material polymerization for manufacturing non-toxic lenses for the eye. The spectral limits for determining the biocompatibility of samples can be related to the intensity ratio of two bands only in the FTIR spectra of siloxane. Siloxane-poly(urethane) block copolymers and other materials for implants have been studied. Passivated surfaces of implants have been obtained and registered by methods of Fourier Transform Spectroscopy.

  9. Preliminary Thermal Characterization of a Fully-Passive Wireless Backscattering Neuro-Recording Microsystem

    NASA Technical Reports Server (NTRS)

    Schwerdt, H. N.; Xu, W.; Shekhar, S.; Chae, J.; Miranda, F. A.

    2011-01-01

    We present analytical and experimental thermal characteristics of a battery-less, fully-passive wireless backscattering microsystem for recording of neuropotentials. A major challenge for cortically implantable microsystems involves minimizing the heat dissipated by on-chip circuitry, which can lead to permanent brain damage. Therefore, knowledge of temperature changes induced by implantable microsystems while in operation is of utmost importance. In this work, a discrete diode appended to the neuro-recording microsystem has been used to indirectly monitor the aforesaid temperature changes. Using this technique, the maximum temperature rise measured for the microsystem while in operation was 0.15 +/- 0.1 C, which is significantly less than current safety guidelines. Specific absorption ratio (SAR) due to the microsystem was also computed to further demonstrate fully-passive functionality of the neuro-recording microsystem.

  10. Nucleus accumbens stimulation in pathological obesity.

    PubMed

    Harat, Marek; Rudaś, Marcin; Zieliński, Piotr; Birska, Julita; Sokal, Paweł

    2016-01-01

    One of the potential treatment methods of obesity is deep brain stimulation (DBS) of nucleus accumbens. We describe the case of 19 years old woman with hypothalamic obesity. She weighted 151.4 kg before DBS and the non-surgical methods proved to be inefficient. She was treated with implantation of DBS electrode to nucleus accumbens bilaterally. Results were measured with body mass index and neuropsychological tests. Follow-up was 14 months. Fourteen months after surgery weight was 138 kg, BMI was 48.3. Neuropsychological test results were intact. The presented case supports the thesis of treatment of obesity with nucleus accumbens stimulation. PMID:27154450

  11. Implants in conjunction with removable partial dentures: a literature review.

    PubMed

    Mijiritsky, Eitan

    2007-06-01

    Although the benefits of implant-borne removable prostheses are readily apparent for the fully edentulous patient and have been well documented, there is a paucity of studies concerning the combination of implants with removable partial dentures in partially edentulous patients. The aim of this article is to review the literature regarding implants with removable partial dentures and evaluate the evidence for this clinical approach. A MEDLINE/PubMed search from 1990 to 2006, focusing on the use of implants with removable partial dentures and related features, was supplemented with a hand search to identify relevant peer-reviewed English articles published in dental journals and textbooks on removable partial dentures. PMID:17563505

  12. Fully Regressive Melanoma: A Case Without Metastasis.

    PubMed

    Ehrsam, Eric; Kallini, Joseph R; Lebas, Damien; Khachemoune, Amor; Modiano, Philippe; Cotten, Hervé

    2016-08-01

    Fully regressive melanoma is a phenomenon in which the primary cutaneous melanoma becomes completely replaced by fibrotic components as a result of host immune response. Although 10 to 35 percent of cases of cutaneous melanomas may partially regress, fully regressive melanoma is very rare; only 47 cases have been reported in the literature to date. AH of the cases of fully regressive melanoma reported in the literature were diagnosed in conjunction with metastasis on a patient. The authors describe a case of fully regressive melanoma without any metastases at the time of its diagnosis. Characteristic findings on dermoscopy, as well as the absence of melanoma on final biopsy, confirmed the diagnosis. PMID:27672418

  13. Multichannel Cochlear Implantation and the Organization of Early Speech.

    ERIC Educational Resources Information Center

    McCaffrey, Helen A.; Davis, Barbara L.; MacNeilage, Peter F.; von Hapsburg, Deborah

    1999-01-01

    A case study of a child who was stimulated with a cochlear implant at age 25 months is reported. Postimplantation, nasals decreased and other consonant types increased, particularly alveolars. The vowel space expanded, including increased production of diphthongs. Serial organization of speech postimplantation mirrored basic motor propensities in…

  14. Hearing Preservation after Cochlear Implantation: UNICAMP Outcomes

    PubMed Central

    de Carvalho, Guilherme Machado; Guimaraes, Alexandre C.; Duarte, Alexandre S. M.; Muranaka, Eder B.; Soki, Marcelo N.; Martins, Renata S. Zanotello; Bianchini, Walter A.; Paschoal, Jorge R.; Castilho, Arthur M.

    2013-01-01

    Background. Electric-acoustic stimulation (EAS) is an excellent choice for people with residual hearing in low frequencies but not high frequencies and who derive insufficient benefit from hearing aids. For EAS to be effective, subjects' residual hearing must be preserved during cochlear implant (CI) surgery. Methods. We implanted 6 subjects with a CI. We used a special surgical technique and an electrode designed to be atraumatic. Subjects' rates of residual hearing preservation were measured 3 times postoperatively, lastly after at least a year of implant experience. Subjects' aided speech perception was tested pre- and postoperatively with a sentence test in quiet. Subjects' subjective responses assessed after a year of EAS or CI experience. Results. 4 subjects had total or partial residual hearing preservation; 2 subjects had total residual hearing loss. All subjects' hearing and speech perception benefited from cochlear implantation. CI diminished or eliminated tinnitus in all 4 subjects who had it preoperatively. 5 subjects reported great satisfaction with their new device. Conclusions. When we have more experience with our surgical technique we are confident we will be able to report increased rates of residual hearing preservation. Hopefully, our study will raise the profile of EAS in Brazil and Latin/South America. PMID:23573094

  15. Perioperative Management of Multiple Noncardiac Implantable Electronic Devices.

    PubMed

    Ramos, Juan A; Brull, Sorin J

    2015-12-01

    The number of patients with noncardiac implantable electronic devices is increasing, and the absence of perioperative management standards, guidelines, practice parameters, or expert consensus statements presents clinical challenges. A 69-year-old woman presented for latissimus dorsi breast reconstruction. The patient had previously undergone implantation of a spinal cord stimulator, a gastric pacemaker, a sacral nerve stimulator, and an intrathecal morphine pump. After consultation with device manufacturers, the devices with patient programmability were switched off. Bipolar cautery was used intraoperatively. Postoperatively, all devices were interrogated to ensure appropriate functioning before home discharge. Perioperative goals include complete preoperative radiologic documentation of device component location, minimizing electromagnetic interference, and avoiding mechanical damage to implanted device components.

  16. Chip-scale hermetic feedthroughs for implantable bionics.

    PubMed

    Guenther, Thomas; Dodds, Christopher W D; Lovell, Nigel H; Suaning, Gregg J

    2011-01-01

    Most implantable medical devices such as cochlear implants and visual prostheses require protection of the stimulating electronics. This is achieved by way of a hermetic feedthrough system which typically features three important attributes: biocompatibility with the human body, device hermeticity and density of feedthrough conductors. On the quest for building a visual neuroprosthesis, a high number of stimulating channels is required. This has encouraged new technologies with higher rates of production yield and further miniaturization. An Al(2)O(3) based feedthrough system has been developed comprising up to 20 platinum feedthroughs per square millimeter. Ceramics substrates are shown to have leak rates below 1 × 10(-12) atm × cc/s, thus exceeding the resolution limits of most commercially available leak detectors. A sheet resistance of 0.05 Ω can be achieved. This paper describes the design, fabrication process and hermeticity testing of high density feedthroughs for use in neuroprosthetic implants.

  17. Perioperative Management of Multiple Noncardiac Implantable Electronic Devices.

    PubMed

    Ramos, Juan A; Brull, Sorin J

    2015-12-01

    The number of patients with noncardiac implantable electronic devices is increasing, and the absence of perioperative management standards, guidelines, practice parameters, or expert consensus statements presents clinical challenges. A 69-year-old woman presented for latissimus dorsi breast reconstruction. The patient had previously undergone implantation of a spinal cord stimulator, a gastric pacemaker, a sacral nerve stimulator, and an intrathecal morphine pump. After consultation with device manufacturers, the devices with patient programmability were switched off. Bipolar cautery was used intraoperatively. Postoperatively, all devices were interrogated to ensure appropriate functioning before home discharge. Perioperative goals include complete preoperative radiologic documentation of device component location, minimizing electromagnetic interference, and avoiding mechanical damage to implanted device components. PMID:26588030

  18. The evolution of embryo implantation.

    PubMed

    McGowen, Michael R; Erez, Offer; Romero, Roberto; Wildman, Derek E

    2014-01-01

    Embryo implantation varies widely in placental mammals. We review this variation in mammals with a special focus on two features: the depth of implantation and embryonic diapause. We discuss the two major types of implantation depth, superficial and interstitial, and map this character on a well-resolved molecular phylogenetic tree of placental mammals. We infer that relatively deep interstitial implantation has independently evolved at least eight times within placental mammals. Moreover, the superficial type of implantation represents the ancestral state for placental mammals. In addition, we review the genes involved in various phases of implantation, and suggest a future direction in investigating the molecular evolution of implantation-related genes. PMID:25023681

  19. Impact of polymer structure and composition on fully resorbable endovascular scaffold performance

    PubMed Central

    Ferdous, Jahid; Kolachalama, Vijaya B.; Shazly, Tarek

    2014-01-01

    Fully erodible endovascular scaffolds are being increasingly considered for the treatment of obstructive arterial disease owing to their potential to mitigate long-term risks associated with permanent alternatives. While complete scaffold erosion facilitates vessel healing, generation and release of material degradation by-products from candidate materials such as poly-l-lactide (PLLA) may elicit local inflammatory responses that limit implant efficacy. We developed a computational framework to quantify how the compositional and structural parameters of PLLA-based fully erodible endovascular scaffolds affect degradation kinetics, erosion kinetics and the transient accumulation of material by-products within the arterial wall. Parametric studies reveal that, while some material properties have similar effects on these critical processes, others induce qualitatively opposing responses. For example, scaffold degradation is only mildly responsive to changes in either PLLA polydispersity or the initial degree of crystallinity, while the erosion kinetics is comparatively sensitive to crystallinity. Moreover, lactide doping can effectively tune both scaffold degradation and erosion, but a concomitant increase in local byproduct accumulation raises concerns about implant safety. Optimized erodible endovascular scaffolds must precisely balance therapeutic function and biological response over the implant lifetime, where compositional and structural parameters will have differential effects on implant performance. PMID:23261926

  20. Dynamics of auditory plasticity after cochlear implantation: a longitudinal study.

    PubMed

    Pantev, C; Dinnesen, A; Ross, B; Wollbrink, A; Knief, A

    2006-01-01

    Human representational cortex may fundamentally alter its organization and (re)gain the capacity for auditory processing even when it is deprived of its input for more than two decades. Stimulus-evoked brain activity was recorded in post-lingual deaf patients after implantation of a cochlear prosthesis, which partly restored their hearing. During a 2 year follow-up study this activity revealed almost normal component configuration and was localized in the auditory cortex, demonstrating adequacy of the cochlear implant stimulation. Evoked brain activity increased over several months after the cochlear implant was turned on. This is taken as a measure of the temporal dynamics of plasticity of the human auditory system after implantation of cochlear prosthesis. PMID:15843632

  1. Industrial applications of ion implantation into metal surfaces

    SciTech Connect

    Williams, J.M.

    1987-07-01

    The modern materials processing technique, ion implantation, has intriguing and attractive features that stimulate the imaginations of scientists and technologists. Success of the technique for introducing dopants into semiconductors has resulted in a stable and growing infrastructure of capital equipment and skills for use of the technique in the economy. Attention has turned to possible use of ion implantation for modification of nearly all surface related properties of materials - optical, chemical and corrosive, tribological, and several others. This presentation provides an introduction to fundamental aspects of equipment, technique, and materials science of ion implantation. Practical and economic factors pertaining to the technology are discussed. Applications and potential applications are surveyed. There are already available a number of ion-implanted products, including ball-and-roller bearings and races, punches-and-dies, injection screws for plastics molding, etc., of potential interest to the machine tool industry.

  2. Bioceramic Implant Induces Bone Healing of Cranial Defects

    PubMed Central

    Kihlström, Lars; Lundgren, Kalle; Trobos, Margarita; Engqvist, Håkan; Thomsen, Peter

    2015-01-01

    Summary: Autologous bone or inert alloplastic materials used in cranial reconstructions are techniques that are associated with resorption, infection, and implant exposure. As an alternative, a calcium phosphate–based implant was developed and previously shown to potentially stimulate bone growth. We here uncover evidence of induced bone formation in 2 patients. Histological examination 9 months postoperatively showed multinuclear cells in the central defect zone and bone ingrowth in the bone-implant border zone. An increased expression of bone-associated markers was detected. The other patient was investigated 50 months postoperatively. Histological examination revealed ceramic materials covered by vascularized compact bone. The bone regenerative effect induced by the implant may potentially improve long-term clinical outcome compared with conventional techniques, which needs to be verified in a clinical study. PMID:26495204

  3. Peri-Implant Diseases

    MedlinePlus

    ... and flossing and regular check-ups from a dental professional. Other risks factors for developing peri-implant disease include previous periodontal disease diagnosis, poor plaque control, smoking , and diabetes . It is essential to routinely ...

  4. Superelastic Orthopedic Implant Coatings

    NASA Astrophysics Data System (ADS)

    Fournier, Eric; Devaney, Robert; Palmer, Matthew; Kramer, Joshua; El Khaja, Ragheb; Fonte, Matthew

    2014-07-01

    The demand for hip and knee replacement surgery is substantial and growing. Unfortunately, most joint replacement surgeries will fail within 10-25 years, thereby requiring an arduous, painful, and expensive revision surgery. To address this issue, a novel orthopedic implant coating material ("eXalt") has been developed. eXalt is comprised of super elastic nitinol wire that is knit into a three-dimensional spacer fabric structure. eXalt expands in vivo to conform to the implantation site and is porous to allow for bone ingrowth. The safety and efficacy of eXalt were evaluated through structural analysis, mechanical testing, and a rabbit implantation model. The results demonstrate that eXalt meets or exceeds the performance of current coating technologies with reduced micromotion, improved osseointegration, and stronger implant fixation in vivo.

  5. Risks of Breast Implants

    MedlinePlus

    ... larger and longer than these conducted so far. Breastfeeding Some women who undergo breast augmentation can successfully ... breast implant silicone shell into breast milk during breastfeeding. Although there are currently no established methods for ...

  6. Deep brain stimulation for movement disorders.

    PubMed

    Larson, Paul S

    2014-07-01

    Deep brain stimulation (DBS) is an implanted electrical device that modulates specific targets in the brain resulting in symptomatic improvement in a particular neurologic disease, most commonly a movement disorder. It is preferred over previously used lesioning procedures due to its reversibility, adjustability, and ability to be used bilaterally with a good safety profile. Risks of DBS include intracranial bleeding, infection, malposition, and hardware issues, such migration, disconnection, or malfunction, but the risk of each of these complications is low--generally ≤ 5% at experienced, large-volume centers. It has been used widely in essential tremor, Parkinson's disease, and dystonia when medical treatment becomes ineffective, intolerable owing to side effects, or causes motor complications. Brain targets implanted include the thalamus (most commonly for essential tremor), subthalamic nucleus (most commonly for Parkinson's disease), and globus pallidus (Parkinson's disease and dystonia), although new targets are currently being explored. Future developments include brain electrodes that can steer current directionally and systems capable of "closed loop" stimulation, with systems that can record and interpret regional brain activity and modify stimulation parameters in a clinically meaningful way. New, image-guided implantation techniques may have advantages over traditional DBS surgery. PMID:24833244

  7. Deep brain stimulation for movement disorders.

    PubMed

    Larson, Paul S

    2014-07-01

    Deep brain stimulation (DBS) is an implanted electrical device that modulates specific targets in the brain resulting in symptomatic improvement in a particular neurologic disease, most commonly a movement disorder. It is preferred over previously used lesioning procedures due to its reversibility, adjustability, and ability to be used bilaterally with a good safety profile. Risks of DBS include intracranial bleeding, infection, malposition, and hardware issues, such migration, disconnection, or malfunction, but the risk of each of these complications is low--generally ≤ 5% at experienced, large-volume centers. It has been used widely in essential tremor, Parkinson's disease, and dystonia when medical treatment becomes ineffective, intolerable owing to side effects, or causes motor complications. Brain targets implanted include the thalamus (most commonly for essential tremor), subthalamic nucleus (most commonly for Parkinson's disease), and globus pallidus (Parkinson's disease and dystonia), although new targets are currently being explored. Future developments include brain electrodes that can steer current directionally and systems capable of "closed loop" stimulation, with systems that can record and interpret regional brain activity and modify stimulation parameters in a clinically meaningful way. New, image-guided implantation techniques may have advantages over traditional DBS surgery.

  8. Ion implantation at elevated temperatures

    SciTech Connect

    Lam, N.Q.; Leaf, G.K.

    1985-11-01

    A kinetic model has been developed to investigate the synergistic effects of radiation-enhanced diffusion, radiation-induced segregation and preferential sputtering on the spatial redistribution of implanted solutes during implantation at elevated temperatures. Sample calculations were performed for Al and Si ions implanted into Ni. With the present model, the influence of various implantation parameters on the evolution of implant concentration profiles could be examined in detail.

  9. Implant treatment planning: endodontic considerations.

    PubMed

    Simonian, Krikor; Frydman, Alon; Verdugo, Fernando; Roges, Rafael; Kar, Kian

    2014-12-01

    Implants are a predictable and effective method for replacing missing teeth. Some clinicians have advocated extraction and replacement of compromised but treatable teeth on the assumption that implants will outperform endodontically and/or periodontally treated teeth. However, evidence shows that conventional therapy is as effective as implant treatment. With data on implants developing complications long term and a lack of predictable treatment for peri-implantitis, retaining and restoring the natural dentition should be the first choice when possible. PMID:25928961

  10. Computational stochastic model of ions implantation

    SciTech Connect

    Zmievskaya, Galina I. Bondareva, Anna L.; Levchenko, Tatiana V.; Maino, Giuseppe

    2015-03-10

    Implantation flux ions into crystal leads to phase transition /PT/ 1-st kind. Damaging lattice is associated with processes clustering vacancies and gaseous bubbles as well their brownian motion. System of stochastic differential equations /SDEs/ Ito for evolution stochastic dynamical variables corresponds to the superposition Wiener processes. The kinetic equations in partial derivatives /KE/, Kolmogorov-Feller and Einstein-Smolukhovskii, were formulated for nucleation into lattice of weakly soluble gases. According theory, coefficients of stochastic and kinetic equations uniquely related. Radiation stimulated phase transition are characterized by kinetic distribution functions /DFs/ of implanted clusters versus their sizes and depth of gas penetration into lattice. Macroscopic parameters of kinetics such as the porosity and stress calculated in thin layers metal/dielectric due to Xe{sup ++} irradiation are attracted as example. Predictions of porosity, important for validation accumulation stresses in surfaces, can be applied at restoring of objects the cultural heritage.

  11. Compression, cochlear implants, and psychophysical laws

    NASA Astrophysics Data System (ADS)

    Zeng, Fan-Gang

    2001-05-01

    Cochlear compression contributes significantly to sharp frequency tuning and wide dynamic range in audition. The physiological mechanism underlying the compression has been traced to the outer hair cell function. Electric stimulation of the auditory nerve in cochlear implants bypasses this compression function, serving as a research tool to delineate the peripheral and central contributions to auditory functions. In this talk, I will compare psychophysical performance between acoustic and electric hearing in intensity, frequency, and time processing, and pay particular attention to the data that demonstrate the role of cochlear compression. Examples include both the cochlear-implant listeners' extremely narrow dynamic range and poor pitch discrimination and their exquisite sensitivity to changes in amplitude and phase. A unified view on the complementary contributions of cochlear compression and central expansion will be developed to account for Webers' law and Stevens power law.

  12. Biomaterials in cochlear implants

    PubMed Central

    Stöver, Timo; Lenarz, Thomas

    2011-01-01

    The cochlear implant (CI) represents, for almost 25 years now, the gold standard in the treatment of children born deaf and for postlingually deafened adults. These devices thus constitute the greatest success story in the field of ‘neurobionic’ prostheses. Their (now routine) fitting in adults, and especially in young children and even babies, places exacting demands on these implants, particularly with regard to the biocompatibility of a CI’s surface components. Furthermore, certain parts of the implant face considerable mechanical challenges, such as the need for the electrode array to be flexible and resistant to breakage, and for the implant casing to be able to withstand external forces. As these implants are in the immediate vicinity of the middle-ear mucosa and of the junction to the perilymph of the cochlea, the risk exists – at least in principle – that bacteria may spread along the electrode array into the cochlea. The wide-ranging requirements made of the CI in terms of biocompatibility and the electrode mechanism mean that there is still further scope – despite the fact that CIs are already technically highly sophisticated – for ongoing improvements to the properties of these implants and their constituent materials, thus enhancing the effectiveness of these devices. This paper will therefore discuss fundamental material aspects of CIs as well as the potential for their future development. PMID:22073103

  13. Simple Implant Augmentation Rhinoplasty.

    PubMed

    Nguyen, Anh H; Bartlett, Erica L; Kania, Katarzyna; Bae, Sang Mo

    2015-11-01

    Augmentation rhinoplasty among Asian patients is often performed to improve the height of the nasal dorsum. As the use of autogenous tissues poses certain limitations, alloplastic materials are a viable alternative with a long history of use in Asia. The superiority of one implant prosthesis over another for augmentation rhinoplasty is a matter of debate, with each material representing varying strengths and weaknesses, indications for use, and precautions to consider in nasal implant placement. An implant prosthesis should be used on a case-by-case basis. Augmentation rhinoplasty requires the consideration of specific anatomical preoperative factors, including the external nose, nasal length, nasofrontal angle, humps, and facial proportions. It is equally important to consider several operative guidelines to appropriately shape implants to minimize the occurrence of adverse effects and postoperative complications. The most common postoperative complications include infection, nasal height change, movement of implant prosthesis, and silicone implant protrusion. In addition, the surgeon should consider the current standards of Asian beauty aesthetics to better understand the patient's desired outcome. PMID:26648804

  14. Dexamethasone: intravitreal implant.

    PubMed

    2011-01-01

    Macular oedema is one of the complications of retinal vein occlusion. About half of the patients recover spontaneously within 3 to 6 months. There is currently no drug that improves outcome. An intravitreal implant delivering 0.7 mg of dexamethasone has been authorised for the treatment of macular oedema in this setting. Clinical assessment is based on two double-blind randomised trials including a total of 1267 patients, comparing treatment with intravitreal implants delivering about 0.7 mg or 0.35 mg of dexamethasone, versus a sham procedure. Despite a more rapid initial improvement with dexamethasone, the number of patients whose reading ability improved at 6 months did not significantly differ between the groups. A retrospective subgroup analysis raised the possibility that dexamethasone implants may be beneficial in patients with central retinal vein occlusion. The adverse effects of dexamethasone intravitreal implants are the same as those of intraocular steroid injections, including elevated intraocular pressure (25% of patients), cataracts (27%), conjunctival haemorrhage (20%), and ocular pain. In practice, dexamethasone intravitreal implants do not have a positive harm-benefit balance in most patients with macular oedema following retinal vein occlusion. More rapid recovery after central vein occlusion remains to be confirmed. Pending such studies, it is better to avoid using dexamethasone implants. Patients should instead receive ophthalmologic monitoring to detect and manage possible complications, and any risk factors should be treated.

  15. 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

  16. Titanium implant impairment and surrounding muscle cell death following neuro-myoelectrostimulation: An in vivo study.

    PubMed

    Lecocq, Mathieu; Félix, Marie-Solenne; Linares, Jean-Marc; Chaves-Jacob, Julien; Decherchi, Patrick; Dousset, Erick

    2015-11-01

    Electrical currents have deleterious effects on biomedical metallic implants. However, following arthroplasty, neuro-myoelectrostimulation (NMES) is often used in patient rehabilitation. Such a rehabilitation technique could compromise patient recovery through deleterious effects on metallic alloys and biological tissues. The purpose of our study was to assess the effects of NMES on a Ti6Al4V implant placed in a rat tibial crest and the surrounding muscle tissues. This in vivo study allowed to bring to the fore the prosthesis behavior under mechanical and electromagnetic loads induced by NEMS stimulation. After 3 weeks, implant-to-bone adhesion significantly decreased in stimulated animals compared with nonstimulated animals. Surface mapping indicated titanium implant degradation after NMES. Furthermore, NMES alone did not induce muscle damage contrary to that found in implanted animals. The muscle damage rate was significantly higher in implanted and stimulated animals compared with implanted-only animals. It seems obvious that rehabilitation programs using the NMES technique could induce early deterioration of biomaterial employed for surgical implants. Clinicians should reconsider the use of NMES as a rehabilitation technique for patients with titanium prostheses.

  17. A Programmable High-Voltage Compliance Neural Stimulator for Deep Brain Stimulation in Vivo

    PubMed Central

    Gong, Cihun-Siyong Alex; Lai, Hsin-Yi; Huang, Sy-Han; Lo, Yu-Chun; Lee, Nicole; Chen, Pin-Yuan; Tu, Po-Hsun; Yang, Chia-Yen; Lin, James Chang-Chieh; Chen, You-Yin

    2015-01-01

    Deep brain stimulation (DBS) is one of the most effective therapies for movement and other disorders. The DBS neurosurgical procedure involves the implantation of a DBS device and a battery-operated neurotransmitter, which delivers electrical impulses to treatment targets through implanted electrodes. The DBS modulates the neuronal activities in the brain nucleus for improving physiological responses as long as an electric discharge above the stimulation threshold can be achieved. In an effort to improve the performance of an implanted DBS device, the device size, implementation cost, and power efficiency are among the most important DBS device design aspects. This study aims to present preliminary research results of an efficient stimulator, with emphasis on conversion efficiency. The prototype stimulator features high-voltage compliance, implemented with only a standard semiconductor process, without the use of extra masks in the foundry through our proposed circuit structure. The results of animal experiments, including evaluation of evoked responses induced by thalamic electrical stimuli with our fabricated chip, were shown to demonstrate the proof of concept of our design. PMID:26029954

  18. A programmable high-voltage compliance neural stimulator for deep brain stimulation in vivo.

    PubMed

    Gong, Cihun-Siyong Alex; Lai, Hsin-Yi; Huang, Sy-Han; Lo, Yu-Chun; Lee, Nicole; Chen, Pin-Yuan; Tu, Po-Hsun; Yang, Chia-Yen; Lin, James Chang-Chieh; Chen, You-Yin

    2015-05-28

    Deep brain stimulation (DBS) is one of the most effective therapies for movement and other disorders. The DBS neurosurgical procedure involves the implantation of a DBS device and a battery-operated neurotransmitter, which delivers electrical impulses to treatment targets through implanted electrodes. The DBS modulates the neuronal activities in the brain nucleus for improving physiological responses as long as an electric discharge above the stimulation threshold can be achieved. In an effort to improve the performance of an implanted DBS device, the device size, implementation cost, and power efficiency are among the most important DBS device design aspects. This study aims to present preliminary research results of an efficient stimulator, with emphasis on conversion efficiency. The prototype stimulator features high-voltage compliance, implemented with only a standard semiconductor process, without the use of extra masks in the foundry through our proposed circuit structure. The results of animal experiments, including evaluation of evoked responses induced by thalamic electrical stimuli with our fabricated chip, were shown to demonstrate the proof of concept of our design.

  19. Finite element simulation of ultrasonic wave propagation in a dental implant for biomechanical stability assessment.

    PubMed

    Vayron, Romain; Nguyen, Vu-Hieu; Bosc, Romain; Naili, Salah; Haïat, Guillaume

    2015-10-01

    Dental implant stability, which is an important parameter for the surgical outcome, can now be assessed using quantitative ultrasound. However, the acoustical propagation in dental implants remains poorly understood. The objective of this numerical study was to understand the propagation phenomena of ultrasonic waves in cylindrically shaped prototype dental implants and to investigate the sensitivity of the ultrasonic response to the surrounding bone quantity and quality. The 10-MHz ultrasonic response of the implant was calculated using an axisymetric 3D finite element model, which was validated by comparison with results obtained experimentally and using a 2D finite difference numerical model. The results show that the implant ultrasonic response changes significantly when a liquid layer is located at the implant interface compared to the case of an interface fully bounded with bone tissue. A dedicated model based on experimental measurements was developed in order to account for the evolution of the bone biomechanical properties at the implant interface. The effect of a gradient of material properties on the implant ultrasonic response is determined. Based on the reproducibility of the measurement, the results indicate that the device should be sensitive to the effects of a healing duration of less than one week. In all cases, the amplitude of the implant response is shown to decrease when the dental implant primary and secondary stability increase, which is consistent with the experimental results. This study paves the way for the development of a quantitative ultrasound method to evaluate dental implant stability.

  20. Osseointegration into a Novel Titanium Foam Implant in the Distal Femur of a Rabbit

    PubMed Central

    Willie, Bettina M.; Yang, Xu; Kelly, Natalie H.; Merkow, Justin; Gagne, Shawn; Ware, Robin; Wright, Timothy M.; Bostrom, Mathias P.G.

    2010-01-01

    A novel porous titanium foam implant has recently been developed to enhance biological fixation of orthopaedic implants to bone. The aim of this study was to examine the mechanical and histological characteristics of bone apposition into two different pore sizes of this titanium foam (565 and 464 micron mean void intercept length) and to compare these characteristics to those obtained with a fully porous conventionally sintered titanium bead implant. Cylindrical implants were studied in a rabbit distal femoral intramedullary osseointegration model at time zero and at 3, 6, and 12 weeks. The amount of bone ingrowth, amount of periprosthetic bone, and mineral apposition rate of periprosthetic bone measured did not differ among the three implant designs at 3, 6, or 12 weeks. By 12 weeks, the interface stiffness and maximum load of the beaded implant was significantly greater than either foam implant. No significant difference was found in the interface stiffness or maximum load between the two foam implant designs at 3, 6, or 12 weeks. The lower compressive modulus of the foam compared to the more dense sintered beaded implants likely contributed to the difference in failure mode. However, the foam implants have a similar compressive modulus to other clinically successful coatings, suggesting they are nonetheless clinically adequate. Additional studies are required to confirm this in weight-bearing models. Histological data suggest that these novel titanium foam implants are a promising alternative to current porous coatings and should be further investigated for clinical application in cementless joint replacement. PMID:20024964

  1. Finite element simulation of ultrasonic wave propagation in a dental implant for biomechanical stability assessment.

    PubMed

    Vayron, Romain; Nguyen, Vu-Hieu; Bosc, Romain; Naili, Salah; Haïat, Guillaume

    2015-10-01

    Dental implant stability, which is an important parameter for the surgical outcome, can now be assessed using quantitative ultrasound. However, the acoustical propagation in dental implants remains poorly understood. The objective of this numerical study was to understand the propagation phenomena of ultrasonic waves in cylindrically shaped prototype dental implants and to investigate the sensitivity of the ultrasonic response to the surrounding bone quantity and quality. The 10-MHz ultrasonic response of the implant was calculated using an axisymetric 3D finite element model, which was validated by comparison with results obtained experimentally and using a 2D finite difference numerical model. The results show that the implant ultrasonic response changes significantly when a liquid layer is located at the implant interface compared to the case of an interface fully bounded with bone tissue. A dedicated model based on experimental measurements was developed in order to account for the evolution of the bone biomechanical properties at the implant interface. The effect of a gradient of material properties on the implant ultrasonic response is determined. Based on the reproducibility of the measurement, the results indicate that the device should be sensitive to the effects of a healing duration of less than one week. In all cases, the amplitude of the implant response is shown to decrease when the dental implant primary and secondary stability increase, which is consistent with the experimental results. This study paves the way for the development of a quantitative ultrasound method to evaluate dental implant stability. PMID:25619479

  2. Electrochemical properties of titanium nitride nerve stimulation electrodes: an in vitro and in vivo study.

    PubMed

    Meijs, Suzan; Fjorback, Morten; Jensen, Carina; Sørensen, Søren; Rechendorff, Kristian; Rijkhoff, Nico J M

    2015-01-01

    The in vivo electrochemical behavior of titanium nitride (TiN) nerve stimulation electrodes was compared to their in vitro behavior for a period of 90 days. Ten electrodes were implanted in two Göttingen minipigs. Four of these were used for electrical stimulation and electrochemical measurements. Five electrodes were kept in Ringer's solution at 37.5°C, of which four were used for electrical stimulation and electrochemical measurements. The voltage transients measured in vivo were 13 times greater than in vitro at implantation and they continued to increase with time. The electrochemical properties in vivo and the tissue resistance (Rtissue) followed a similar trend with time. There was no consistent significant difference between the electrochemical properties of the in vivo and in vitro electrodes after the implanted period. The differences between the in vivo and in vitro electrodes during the implanted period show that the evaluation of electrochemical performance of implantable stimulation electrodes cannot be substituted with in vitro measurements. After the implanted period, however, the performance of the in vivo and in vitro electrodes in saline was similar. In addition, the changes observed over time during the post-implantation period regarding the electrochemical properties of the in vivo electrodes and Rtissue were similar, which indicates that these changes are due to the foreign body response to implantation.

  3. Electrochemical properties of titanium nitride nerve stimulation electrodes: an in vitro and in vivo study

    PubMed Central

    Meijs, Suzan; Fjorback, Morten; Jensen, Carina; Sørensen, Søren; Rechendorff, Kristian; Rijkhoff, Nico J. M.

    2015-01-01

    The in vivo electrochemical behavior of titanium nitride (TiN) nerve stimulation electrodes was compared to their in vitro behavior for a period of 90 days. Ten electrodes were implanted in two Göttingen minipigs. Four of these were used for electrical stimulation and electrochemical measurements. Five electrodes were kept in Ringer's solution at 37.5°C, of which four were used for electrical stimulation and electrochemical measurements. The voltage transients measured in vivo were 13 times greater than in vitro at implantation and they continued to increase with time. The electrochemical properties in vivo and the tissue resistance (Rtissue) followed a similar trend with time. There was no consistent significant difference between the electrochemical properties of the in vivo and in vitro electrodes after the implanted period. The differences between the in vivo and in vitro electrodes during the implanted period show that the evaluation of electrochemical performance of implantable stimulation electrodes cannot be substituted with in vitro measurements. After the implanted period, however, the performance of the in vivo and in vitro electrodes in saline was similar. In addition, the changes observed over time during the post-implantation period regarding the electrochemical properties of the in vivo electrodes and Rtissue were similar, which indicates that these changes are due to the foreign body response to implantation. PMID:26300717

  4. Augmentation of transfers for a quadriplegic patient using an implanted FNS system. Case report.

    PubMed

    Marsolais, E B; Scheiner, A; Miller, P C; Kobetic, R; Daly, J J

    1994-08-01

    A 22 year old man with incomplete quadriplegia (C6-7) was unable to perform either a sliding or a pivot transfer. He was instrumented with an implanted functional neuromuscular stimulation (FNS) system, radio frequency-linked to a belt-worn controller. The system activated eight muscles selected from among quadriceps, hamstrings, posterior portion of the adductor magnus, gluteus maximus, and erector spinae, bilaterally. The two-stage implantation procedure included electrode implantation with percutaneous leads followed by stimulator implantation and removal of the percutaneous leads. All implants were well tolerated with no adverse effects. The subject was able independently to put on the external controller portion of the system and to perform a standing pivot transfer with only standby assistance. An unexpected outcome of the FNS system use was increased voluntary upper body strength that resulted in improvement of the sliding transfer from 'inability' to 'independent'. PMID:7970864

  5. [A totally implantable hearing aid for inner ear deafness: TICA LZ 3001].

    PubMed

    Leysieffer, H; Baumann, J W; Mayer, R; Müller, D; Müller, G; Schön, T; Volz, A; Zenner, H P

    1998-10-01

    Recently, Zenner et al. implanted the first totally implantable electronic hearing devices in patients with SNHL (HNO 46 [1998] 844-852). In the present report, technical and audiological features of the implant TICA are published. The development of the piezoelectric transducer and the microphone for implantation in the posterior wall of the auditory canal as components for the present fully implantable hearing system has already been described (HNO 45, 1997, 792-880). Here we report about our experience with the electronic main module that completes the TICA LZ 3001 system. This module is suited for implantation in the mastoid bone and contains the signal-processing electronics and an integrated battery that can be recharged transcutaneously with a portable charger. The recharging time is around 2 h for an implant operating time of 50 h. The microphone and transducer connectors allow for easy replacement of the main module when the battery lifetime is reached. This lifetime is around 3-5 years. A small wireless remote control allows volume adjustment, contains an on/off switch, and permits selection of four different individual hearing programs. The basic audiological features are provided by a flexible, digitally programmable 3-channel-AGC-system with a peak clipping function. The total bandwidth is around 10 kHz. To our knowledge this is the first fully implantable hearing system that has been in implanted in humans.

  6. Does the Implant Surgical Technique Affect the Primary and/or Secondary Stability of Dental Implants? A Systematic Review

    PubMed Central

    Shadid, Rola Muhammed; Sadaqah, Nasrin Rushdi; Othman, Sahar Abdo

    2014-01-01

    Background. A number of surgical techniques for implant site preparation have been advocated to enhance the implant of primary and secondary stability. However, there is insufficient scientific evidence to support the association between the surgical technique and implant stability. Purpose. This review aimed to investigate the influence of different surgical techniques including the undersized drilling, the osteotome, the piezosurgery, the flapless procedure, and the bone stimulation by low-level laser therapy on the primary and/or secondary stability of dental implants. Materials and methods. A search of PubMed, Cochrane Library, and grey literature was performed. The inclusion criteria comprised observational clinical studies and randomized controlled trials (RCTs) conducted in patients who received dental implants for rehabilitation, studies that evaluated the association between the surgical technique and the implant primary and/or secondary stability. The articles selected were carefully read and classified as low, moderate, and high methodological quality and data of interest were tabulated. Results. Eight clinical studies were included then they were classified as moderate or high methodological quality and control of bias. Conclusions. There is a weak evidence suggesting that any of previously mentioned surgical techniques could influence the primary and/or secondary implant stability. PMID:25126094

  7. 21 CFR 882.5820 - Implanted cerebellar stimulator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... premarket approval application (PMA) or notice of completion of a product development protocol (PDP) is required. A PMA or notice of completion of a PDP is required to be filed with the Food and Drug..., 1976 shall have an approved PMA or declared completed PDP in effect before beginning...

  8. 21 CFR 882.5820 - Implanted cerebellar stimulator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... premarket approval application (PMA) or notice of completion of a product development protocol (PDP) is required. A PMA or notice of completion of a PDP is required to be filed with the Food and Drug..., 1976 shall have an approved PMA or declared completed PDP in effect before beginning...

  9. Evaluation of intradural stimulation efficiency and selectivity in a computational model of spinal cord stimulation.

    PubMed

    Howell, Bryan; Lad, Shivanand P; Grill, Warren M

    2014-01-01

    Spinal cord stimulation (SCS) is an alternative or adjunct therapy to treat chronic pain, a prevalent and clinically challenging condition. Although SCS has substantial clinical success, the therapy is still prone to failures, including lead breakage, lead migration, and poor pain relief. The goal of this study was to develop a computational model of SCS and use the model to compare activation of neural elements during intradural and extradural electrode placement. We constructed five patient-specific models of SCS. Stimulation thresholds predicted by the model were compared to stimulation thresholds measured intraoperatively, and we used these models to quantify the efficiency and selectivity of intradural and extradural SCS. Intradural placement dramatically increased stimulation efficiency and reduced the power required to stimulate the dorsal columns by more than 90%. Intradural placement also increased selectivity, allowing activation of a greater proportion of dorsal column fibers before spread of activation to dorsal root fibers, as well as more selective activation of individual dermatomes at different lateral deviations from the midline. Further, the results suggest that current electrode designs used for extradural SCS are not optimal for intradural SCS, and a novel azimuthal tripolar design increased stimulation selectivity, even beyond that achieved with an intradural paddle array. Increased stimulation efficiency is expected to increase the battery life of implantable pulse generators, increase the recharge interval of rechargeable implantable pulse generators, and potentially reduce stimulator volume. The greater selectivity of intradural stimulation may improve the success rate of SCS by mitigating the sensitivity of pain relief to malpositioning of the electrode. The outcome of this effort is a better quantitative understanding of how intradural electrode placement can potentially increase the selectivity and efficiency of SCS, which, in turn

  10. Implant interactions with orthodontics.

    PubMed

    Celenza, Frank

    2012-09-01

    Many situations arise in which orthodontic therapy in conjunction with implant modalities is beneficial, relevant or necessary. These situations might entail orthodontic treatment preparatory to the placement of an implant, such as in the site preparation for implant placement. Traditionally, this has been somewhat well understood, but there are certain guidelines that must be adhered to as well as diagnostic steps that must be followed. Provision of adequate space for implant placement is of paramount importance, but there is also the consideration of tissue manipulation and remodeling which orthodontic therapy can achieve very predictably and orthodontists should be well versed in harnessing and employing this modality of site preparation. In this way, hopeless teeth that are slated for extraction can still be utilized by orthodontic extraction to augment tissues, both hard and soft, thereby facilitating site development. On the corollary, and representing a significant shift in treatment sequencing, there are many situations in which orthodontic mechanotherapy can be simplified, expedited, and facilitated by the placement of an implant and utilization as an integral part of the mechanotherapy. Implants have proven to provide excellent anchorage, and have resulted in a new class of anchorage known as "absolute anchorage". Implants can be harnessed as anchors both in a direct and indirect sense, depending upon the dictates of the case. Further, this has led to the development of orthodontic miniscrew systems and techniques, which can have added features such as flexibility in location and placement, as well as ease of use and removal. As orthodontic appliances evolve, the advent of aligner therapy has become mainstream and well accepted, and many of the aforementioned combined treatment modalities can and should be incorporated into this relatively new treatment modality as well. PMID:23040348

  11. Bioactive macroporous titanium implants highly interconnected.

    PubMed

    Caparrós, Cristina; Ortiz-Hernandez, Mónica; Molmeneu, Meritxell; Punset, Miguel; Calero, José Antonio; Aparicio, Conrado; Fernández-Fairén, Mariano; Perez, Román; Gil, Francisco Javier

    2016-10-01

    Intervertebral implants should be designed with low load requirements, high friction coefficient and low elastic modulus in order to avoid the stress shielding effect on bone. Furthermore, the presence of a highly interconnected porous structure allows stimulating bone in-growth and enhancing implant-bone fixation. The aim of this study was to obtain bioactive porous titanium implants with highly interconnected pores with a total porosity of approximately 57 %. Porous Titanium implants were produced by powder sintering route using the space holder technique with a binder phase and were then evaluated in an in vivo study. The size of the interconnection diameter between the macropores was about 210 μm in order to guarantee bone in-growth through osteblastic cell penetration. Surface roughness and mechanical properties were analyzed. Stiffness was reduced as a result of the powder sintering technique which allowed the formation of a porous network. Compression and fatigue tests exhibited suitable properties in order to guarantee a proper compromise between mechanical properties and pore interconnectivity. Bioactivity treatment effect in novel sintered porous titanium materials was studied by thermo-chemical treatments and were compared with the same material that had undergone different bioactive treatments. Bioactive thermo-chemical treatment was confirmed by the presence of sodium titanates on the surface of the implants as well as inside the porous network. Raman spectroscopy results suggested that the identified titanate structures would enhance in vivo apatite formation by promoting ion exchange for the apatite formation process. In vivo results demonstrated that the bioactive titanium achieved over 75 % tissue colonization compared to the 40 % value for the untreated titanium. PMID:27582071

  12. Bioactive macroporous titanium implants highly interconnected.

    PubMed

    Caparrós, Cristina; Ortiz-Hernandez, Mónica; Molmeneu, Meritxell; Punset, Miguel; Calero, José Antonio; Aparicio, Conrado; Fernández-Fairén, Mariano; Perez, Román; Gil, Francisco Javier

    2016-10-01

    Intervertebral implants should be designed with low load requirements, high friction coefficient and low elastic modulus in order to avoid the stress shielding effect on bone. Furthermore, the presence of a highly interconnected porous structure allows stimulating bone in-growth and enhancing implant-bone fixation. The aim of this study was to obtain bioactive porous titanium implants with highly interconnected pores with a total porosity of approximately 57 %. Porous Titanium implants were produced by powder sintering route using the space holder technique with a binder phase and were then evaluated in an in vivo study. The size of the interconnection diameter between the macropores was about 210 μm in order to guarantee bone in-growth through osteblastic cell penetration. Surface roughness and mechanical properties were analyzed. Stiffness was reduced as a result of the powder sintering technique which allowed the formation of a porous network. Compression and fatigue tests exhibited suitable properties in order to guarantee a proper compromise between mechanical properties and pore interconnectivity. Bioactivity treatment effect in novel sintered porous titanium materials was studied by thermo-chemical treatments and were compared with the same material that had undergone different bioactive treatments. Bioactive thermo-chemical treatment was confirmed by the presence of sodium titanates on the surface of the implants as well as inside the porous network. Raman spectroscopy results suggested that the identified titanate structures would enhance in vivo apatite formation by promoting ion exchange for the apatite formation process. In vivo results demonstrated that the bioactive titanium achieved over 75 % tissue colonization compared to the 40 % value for the untreated titanium.

  13. Fully Depleted Charge-Coupled Devices

    SciTech Connect

    Holland, Stephen E.

    2006-05-15

    We have developed fully depleted, back-illuminated CCDs thatbuild upon earlier research and development efforts directed towardstechnology development of silicon-strip detectors used inhigh-energy-physics experiments. The CCDs are fabricated on the same typeof high-resistivity, float-zone-refined silicon that is used for stripdetectors. The use of high-resistivity substrates allows for thickdepletion regions, on the order of 200-300 um, with corresponding highdetection efficiency for near-infrared andsoft x-ray photons. We comparethe fully depleted CCD to thep-i-n diode upon which it is based, anddescribe the use of fully depleted CCDs in astronomical and x-ray imagingapplications.

  14. Scuba diving with cochlear implants.

    PubMed

    Kompis, Martin; Vibert, Dominique; Senn, Pascal; Vischer, Mattheus W; Häusler, Rudolf

    2003-05-01

    We report on a patient with bilateral cochlear implants (a Med-El Combi40 and a Med-El Combi40+), as well as considerable experience in scuba diving with both of his implants. After having been exposed to 68 and 89 dives, respectively, in depths of up to 43 m, both cochlear implants are in working order and the patient continues to receive excellent speech recognition scores with both cochlear implant systems. The presented data show that scuba diving after cochlear implantation is possible over a considerable number of dives without any major negative impact on the implants.

  15. [Subretinal visual implants].

    PubMed

    Stingl, K; Greppmaier, U; Wilhelm, B; Zrenner, E

    2010-12-01

    Visual implants are medical technologies that replace parts of the visual neuronal pathway. The subretinal implant developed by our group is being used in a human trials since 2005 and replaces the function of degenerated photoreceptors by an electronic device in blind patients. The subretinal implant consists of a 70-µm thin microchip with 1500 microphotodiodes each with an amplifier and an electrode with area of 3 mm × 3 mm. The power supply is provided by a subdermal power supply cable. The microchip is implanted under the macula and transforms the light signal into an electrical one, which is referred directly to the bipolar cells. Requirements for a good function of the implant are a preserved function of the inner retina, as well as clear optic media and a good visual acuity in the earlier life. The current technology can mediate a visual field of 10 - 12° and a computed resolution of up to 0.25° visual angle (corresponding to a visual acuity of 63 / 1000 - 80 / 1000) in blind patients. The so far best results from our studies reached a visual acuity of 21 / 1000 in blind retinitis pigmentosa patients. This overview is intended to inform the ophthalmologist about the current state of the technology and help him/her to advise interested patients.

  16. Changes in gene expression and hearing thresholds after cochlear implantation

    PubMed Central

    Zhang, Hongzheng; Stark, Gemaine; Reiss, Lina

    2016-01-01

    Hypothesis Gene expression changes occur in conjunction with hearing threshold changes after cochlear implantation. Background Between 30–50% of individuals who receive electro-acoustic stimulation (EAS) cochlear implants lose residual hearing after cochlear implantation, reducing the benefits of EAS. The mechanism underlying this hearing loss is unknown; potential pathways include mechanical damage, inflammation, or tissue remodeling changes. Methods Guinea pigs were implanted in one ear with cochlear implant electrode arrays, with non-implanted ears serving as controls, and allowed to recover for 1, 3, 7, or 14 days. Hearing threshold changes were measured over time. Cochlear ribonucleic acid was analyzed using real-time quantitative reverse transcription-polymerase chain reaction from the following gene families: cytokines, tight junction claudins, ion and water (aquaporin) transport channels, gap junction connexins, and tissue remodeling genes. Results Significant increases in expression were observed for cochlear inflammatory genes (Cxcl1, IL-1b, TNFα and Tnfrsf1a/b) and ion homeostasis genes (Scnn1γ, Aqp3 and Gjb3). Upregulation of tissue remodeling genes (TGF-β, MMP2, MMP9) as well as a paracrine gene (CTGF) was also observed. Hearing loss occurred rapidly, peaking at 3 days with some recovery at 7 and 14 days after implantation. MM9 exhibited extreme upregulation of expression and was qualitatively associated with changes in hearing thresholds. Conclusion Cochlear implantation induces similar changes as middle ear inflammation for genes involved in inflammation and ion and water transport function, whereas tissue remodeling changes differ markedly. The upregulation of MMP9 with hearing loss is consistent with previous findings linking stria vascularis vessel changes with cochlear implant-induced hearing loss. PMID:25970030

  17. Failure of Urological Implants in Spinal Cord Injury Patients due to Infection, Malfunction, and Implants Becoming Obsolete due to Medical Progress and Age-Related Changes in Human Body Making Implant Futile: Report of Three Cases.

    PubMed

    Vaidyanathan, Subramanian; Soni, Bakul; Singh, Gurpreet; Hughes, Peter; Selmi, Fahed; Mansour, Paul

    2013-01-01

    Any new clinical data, whether positive or negative, generated about a medical device should be published because health professionals should know which devices do not work, as well as those which do. We report three spinal cord injury patients in whom urological implants failed to work. In the first, paraplegic, patient, a sacral anterior root stimulator failed to produce erection, and a drug delivery system for intracavernosal administration of vasoactive drugs was therefore implanted; however, this implant never functioned (and, furthermore, such penile drug delivery systems to produce erection had effectively become obsolete following the advent of phosphodiesterase type 5 inhibitors). Subsequently, the sacral anterior root stimulator developed a malfunction and the patient therefore learned to perform self-catheterisation. In the second patient, also paraplegic, an artificial urinary sphincter was implanted but the patient developed a postoperative sacral pressure sore. Eight months later, a suprapubic cystostomy was performed as urethral catheterisation was very difficult. The pressure sore had not healed completely even after five years. In the third case, a sacral anterior root stimulator was implanted in a tetraplegic patient in whom, after five years, a penile sheath could not be fitted because of penile retraction. This patient was therefore established on urethral catheter drainage. Later, infection with Staphylococcus aureus around the receiver block necessitated its removal. In conclusion, spinal cord injury patients are at risk of developing pressure sores, wound infections, malfunction of implants, and the inability to use implants because of age-related changes, as well as running the risk of their implants becoming obsolete due to advances in medicine. Some surgical procedures such as dorsal rhizotomy are irreversible. Alternative treatments such as intermittent catheterisations may be less damaging than bladder stimulator in the long term. PMID

  18. Failure of Urological Implants in Spinal Cord Injury Patients due to Infection, Malfunction, and Implants Becoming Obsolete due to Medical Progress and Age-Related Changes in Human Body Making Implant Futile: Report of Three Cases.

    PubMed

    Vaidyanathan, Subramanian; Soni, Bakul; Singh, Gurpreet; Hughes, Peter; Selmi, Fahed; Mansour, Paul

    2013-01-01

    Any new clinical data, whether positive or negative, generated about a medical device should be published because health professionals should know which devices do not work, as well as those which do. We report three spinal cord injury patients in whom urological implants failed to work. In the first, paraplegic, patient, a sacral anterior root stimulator failed to produce erection, and a drug delivery system for intracavernosal administration of vasoactive drugs was therefore implanted; however, this implant never functioned (and, furthermore, such penile drug delivery systems to produce erection had effectively become obsolete following the advent of phosphodiesterase type 5 inhibitors). Subsequently, the sacral anterior root stimulator developed a malfunction and the patient therefore learned to perform self-catheterisation. In the second patient, also paraplegic, an artificial urinary sphincter was implanted but the patient developed a postoperative sacral pressure sore. Eight months later, a suprapubic cystostomy was performed as urethral catheterisation was very difficult. The pressure sore had not healed completely even after five years. In the third case, a sacral anterior root stimulator was implanted in a tetraplegic patient in whom, after five years, a penile sheath could not be fitted because of penile retraction. This patient was therefore established on urethral catheter drainage. Later, infection with Staphylococcus aureus around the receiver block necessitated its removal. In conclusion, spinal cord injury patients are at risk of developing pressure sores, wound infections, malfunction of implants, and the inability to use implants because of age-related changes, as well as running the risk of their implants becoming obsolete due to advances in medicine. Some surgical procedures such as dorsal rhizotomy are irreversible. Alternative treatments such as intermittent catheterisations may be less damaging than bladder stimulator in the long term.

  19. Plasma immersion ion implantation for sub-22 nm node devices: FD-SOI and Tri-Gate

    SciTech Connect

    Duchaine, J.; Milesi, F.; Coquand, R.; Barraud, S.; Reboh, S.; Gonzatti, F.; Mazen, F.; Torregrosa, Frank

    2012-11-06

    Here, we present and discuss the electrical characteristics of fully depleted MOSFET transistors of planar and tridimensional architecture, doped by Plasma Immersion Ion Implantation (PIII) or Beam Line Ion Implantation (BLII). Both techniques delivered similar and satisfactory results in considering the planar architecture. For tri-dimensional Tri-Gate transistors, the results obtained with PIII are superior.

  20. Electrical Implications of Corrosion for Osseointegration of Titanium Implants

    PubMed Central

    Gittens, R.A.; Olivares-Navarrete, R.; Tannenbaum, R.; Boyan, B.D.; Schwartz, Z.

    2011-01-01

    The success rate of titanium implants for dental and orthopedic applications depends on the ability of surrounding bone tissue to integrate with the surface of the device, and it remains far from ideal in patients with bone compromised by physiological factors. The electrical properties and electrical stimulation of bone have been shown to control its growth and healing and can enhance osseointegration. Bone cells are also sensitive to the chemical products generated during corrosion events, but less is known about how the electrical signals associated with corrosion might affect osseointegration. The metallic nature of the materials used for implant applications and the corrosive environments found in the human body, in combination with the continuous and cyclic loads to which these implants are exposed, may lead to corrosion and its corresponding electrochemical products. The abnormal electrical currents produced during corrosion can convert any metallic implant into an electrode, and the negative impact on the surrounding tissue due to these extreme signals could be an additional cause of poor performance and rejection of implants. Here, we review basic aspects of the electrical properties and electrical stimulation of bone, as well as fundamental concepts of aqueous corrosion and its electrical and clinical implications. PMID:21555775

  1. High-voltage-compatible, fully depleted CCDs

    SciTech Connect

    Holland, Stephen E.; Bebek, Chris J.; Dawson, Kyle S.; Emes, JohnE.; Fabricius, Max H.; Fairfield, Jessaym A.; Groom, Don E.; Karcher, A.; Kolbe, William F.; Palaio, Nick P.; Roe, Natalie A.; Wang, Guobin

    2006-05-15

    We describe charge-coupled device (CCD) developmentactivities at the Lawrence Berkeley National Laboratory (LBNL).Back-illuminated CCDs fabricated on 200-300 mu m thick, fully depleted,high-resistivity silicon substrates are produced in partnership with acommercial CCD foundry.The CCDs are fully depleted by the application ofa substrate bias voltage. Spatial resolution considerations requireoperation of thick, fully depleted CCDs at high substrate bias voltages.We have developed CCDs that are compatible with substrate bias voltagesof at least 200V. This improves spatial resolution for a given thickness,and allows for full depletion of thicker CCDs than previously considered.We have demonstrated full depletion of 650-675 mu m thick CCDs, withpotential applications in direct x-ray detection. In this work we discussthe issues related to high-voltage operation of fully depleted CCDs, aswell as experimental results on high-voltage-compatible CCDs.

  2. Immunological aspects of implantation and implantation failure.

    PubMed

    Johnson, P M; Christmas, S E; Vince, G S

    1999-12-01

    The human endometrium contains a significant proportion of leukocytes (8-35% of all cells), the absolute numbers and proportions varying during both the menstrual cycle and early in pregnancy. T cells, macrophages and a population of phenotypically unusual large granular lymphocytes (LGL) are commonly present, although B cells are absent. Relative T cell numbers decrease significantly in first trimester decidua, and hence are unlikely to play an important role in maintenance of human pregnancy, but T cells could be important in implantation where their relative numbers are greater. In addition to producing cytokines, local tissue macrophages may provide an immediate antigen non-specific host defence to infection. Most attention has, nevertheless, focused on a role for LGL in implantation and maintenance of pregnancy since, at the time of implantation, LGL comprise 70-80% of the total endometrial leukocyte population. Although endometrial LGL have been shown to express natural killer (NK) cell-type cytotoxicity against classical NK cell targets, such cytotoxicity against trophoblast is induced only after activation by interleukin (IL)-2. Selective expression of the unusual class I human leukocyte antigen (HLA) molecule, HLA-G, by extravillous cytotrophoblast may assist in protecting invasive cytotrophoblast from potential maternal NK cell attack, probably via interactions with killer inhibitory receptor molecules on LGL. Many cytokines have been demonstrated to be expressed at the maternal-fetal interface although, currently, in mice only two (IL-11 and leukaemia inhibitory factor) appear to be absolutely essential for successful pregnancy outcome. Immune effector cells and cytokines may also play a role in human pregnancy pathologies, such as recurrent early pregnancy loss.

  3. Optimal operating frequency in wireless power transmission for implantable devices.

    PubMed

    Poon, Ada S Y; O'Driscoll, Stephen; Meng, Teresa H

    2007-01-01

    This paper examines short-range wireless powering for implantable devices and shows that existing analysis techniques are not adequate to conclude the characteristics of power transfer efficiency over a wide frequency range. It shows, theoretically and experimentally, that the optimal frequency for power transmission in biological media can be in the GHz-range while existing solutions exclusively focus on the MHz-range. This implies that the size of the receive coil can be reduced by 10(4) times which enables the realization of fully integrated implantable devices. PMID:18003300

  4. Photoreflectance Study of Boron Ion-Implanted (100) Cadmium Telluride

    NASA Technical Reports Server (NTRS)

    Amirtharaj, P. M.; Odell, M. S.; Bowman, R. C., Jr.; Alt, R. L.

    1988-01-01

    Ion implanted (100) cadmium telluride was studied using the contactless technique of photoreflectance. The implantations were performed using 50- to 400-keV boron ions to a maximum dosage of 1.5 x 10(16)/sq cm, and the annealing was accomplished at 500 C under vacuum. The spectral measurements were made at 77 K near the E(0) and E(1) critical points; all the spectra were computer-fitted to Aspnes' theory. The spectral line shapes from the ion damaged, partially recovered and undamaged, or fully recovered regions could be identified, and the respective volume fraction of each phase was estimated.

  5. Design and Evaluation of a Personal Digital Assistant-based Research Platform for Cochlear Implants

    PubMed Central

    Ali, Hussnain; Lobo, Arthur P.; Loizou, Philipos C.

    2014-01-01

    This paper discusses the design, development, features, and clinical evaluation of a personal digital assistant (PDA)-based platform for cochlear implant research. This highly versatile and portable research platform allows researchers to design and perform complex experiments with cochlear implants manufactured by Cochlear Corporation with great ease and flexibility. The research platform includes a portable processor for implementing and evaluating novel speech processing algorithms, a stimulator unit which can be used for electrical stimulation and neurophysio-logic studies with animals, and a recording unit for collecting electroencephalogram/evoked potentials from human subjects. The design of the platform for real time and offline stimulation modes is discussed for electric-only and electric plus acoustic stimulation followed by results from an acute study with implant users for speech intelligibility in quiet and noisy conditions. The results are comparable with users’ clinical processor and very promising for undertaking chronic studies. PMID:23674422

  6. In vivo impedance spectroscopy of deep brain stimulation electrodes

    NASA Astrophysics Data System (ADS)

    Lempka, Scott F.; Miocinovic, Svjetlana; Johnson, Matthew D.; Vitek, Jerrold L.; McIntyre, Cameron C.

    2009-08-01

    Deep brain stimulation (DBS) represents a powerful clinical technology, but a systematic characterization of the electrical interactions between the electrode and the brain is lacking. The goal of this study was to examine the in vivo changes in the DBS electrode impedance that occur after implantation and during clinically relevant stimulation. Clinical DBS devices typically apply high-frequency voltage-controlled stimulation, and as a result, the injected current is directly regulated by the impedance of the electrode-tissue interface. We monitored the impedance of scaled-down clinical DBS electrodes implanted in the thalamus and subthalamic nucleus of a rhesus macaque using electrode impedance spectroscopy (EIS) measurements ranging from 0.5 Hz to 10 kHz. To further characterize our measurements, equivalent circuit models of the electrode-tissue interface were used to quantify the role of various interface components in producing the observed electrode impedance. Following implantation, the DBS electrode impedance increased and a semicircular arc was observed in the high-frequency range of the EIS measurements, commonly referred to as the tissue component of the impedance. Clinically relevant stimulation produced a rapid decrease in electrode impedance with extensive changes in the tissue component. These post-operative and stimulation-induced changes in impedance could play an important role in the observed functional effects of voltage-controlled DBS and should be considered during clinical stimulation parameter selection and chronic animal research studies.

  7. Progress in Fully Automated Abdominal CT Interpretation

    PubMed Central

    Summers, Ronald M.

    2016-01-01

    OBJECTIVE Automated analysis of abdominal CT has advanced markedly over just the last few years. Fully automated assessment of organs, lymph nodes, adipose tissue, muscle, bowel, spine, and tumors are some examples where tremendous progress has been made. Computer-aided detection of lesions has also improved dramatically. CONCLUSION This article reviews the progress and provides insights into what is in store in the near future for automated analysis for abdominal CT, ultimately leading to fully automated interpretation. PMID:27101207

  8. A systematic review of electric-acoustic stimulation: device fitting ranges, outcomes, and clinical fitting practices.

    PubMed

    Incerti, Paola V; Ching, Teresa Y C; Cowan, Robert

    2013-03-01

    Cochlear implant systems that combine electric and acoustic stimulation in the same ear are now commercially available and the number of patients using these devices is steadily increasing. In particular, electric-acoustic stimulation is an option for patients with severe, high frequency sensorineural hearing impairment. There have been a range of approaches to combining electric stimulation and acoustic hearing in the same ear. To develop a better understanding of fitting practices for devices that combine electric and acoustic stimulation, we conducted a systematic review addressing three clinical questions: what is the range of acoustic hearing in the implanted ear that can be effectively preserved for an electric-acoustic fitting?; what benefits are provided by combining acoustic stimulation with electric stimulation?; and what clinical fitting practices have been developed for devices that combine electric and acoustic stimulation? A search of the literature was conducted and 27 articles that met the strict evaluation criteria adopted for the review were identified for detailed analysis. The range of auditory thresholds in the implanted ear that can be successfully used for an electric-acoustic application is quite broad. The effectiveness of combined electric and acoustic stimulation as compared with electric stimulation alone was consistently demonstrated, highlighting the potential value of preservation and utilization of low frequency hearing in the implanted ear. However, clinical procedures for best fitting of electric-acoustic devices were varied. This clearly identified a need for further investigation of fitting procedures aimed at maximizing outcomes for recipients of electric-acoustic devices. PMID:23539259

  9. Dental Implant Complications.

    PubMed

    Liaw, Kevin; Delfini, Ronald H; Abrahams, James J

    2015-10-01

    Dental implants have increased in the last few decades thus increasing the number of complications. Since many of these complications are easily diagnosed on postsurgical images, it is important for radiologists to be familiar with them and to be able to recognize and diagnose them. Radiologists should also have a basic understanding of their treatment. In a pictorial fashion, this article will present the basic complications of dental implants which we have divided into three general categories: biomechanical overload, infection or inflammation, and other causes. Examples of implant fracture, loosening, infection, inflammation from subgingival cement, failure of bone and soft tissue preservation, injury to surround structures, and other complications will be discussed as well as their common imaging appearances and treatment. Lastly, we will review pertinent dental anatomy and important structures that are vital for radiologists to evaluate in postoperative oral cavity imaging.

  10. Infrared neural stimulation: a new stimulation tool for central nervous system applications

    PubMed Central

    Chernov, Mykyta; Roe, Anna Wang

    2014-01-01

    Abstract. The traditional approach to modulating brain function (in both clinical and basic science applications) is to tap into the neural circuitry using electrical currents applied via implanted electrodes. However, it suffers from a number of problems, including the risk of tissue trauma, poor spatial specificity, and the inability to selectively stimulate neuronal subtypes. About a decade ago, optical alternatives to electrical stimulation started to emerge in order to address the shortcomings of electrical stimulation. We describe the use of one optical stimulation technique, infrared neural stimulation (INS), during which short (of the order of a millisecond) pulses of infrared light are delivered to the neural tissue. Very focal stimulation is achieved via a thermal mechanism and stimulation location can be quickly adjusted by redirecting the light. After describing some of the work done in the peripheral nervous system, we focus on the use of INS in the central nervous system to investigate functional connectivity in the visual and somatosensory areas, target specific functional domains, and influence behavior of an awake nonhuman primate. We conclude with a positive outlook for INS as a tool for safe and precise targeted brain stimulation. PMID:26157967

  11. Implantable Heart Aid

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Medrad utilized NASA's Apollo technology to develop a new device called the AID implantable automatic pulse generator which monitors the heart continuously, recognizes the onset of ventricular fibrillation and delivers a corrective electrical shock. AID pulse generator is, in effect, a miniaturized version of the defibrillator used by emergency squads and hospitals to restore rhythmic heartbeat after fibrillation, but has the unique advantage of being permanently available to the patient at risk. Once implanted, it needs no specially trained personnel or additional equipment. AID system consists of a microcomputer, a power source and two electrodes which sense heart activity.

  12. Hydroxylapatite Otologic Implants

    SciTech Connect

    McMillan, A.D.; Lauf, R.J.; Beale, B.; Johnson, R.

    2000-01-01

    A Cooperative Research and Development Agreement (CRADA) between Lockheed Martin Energy Research Corporation (LMER) and Smith and Nephew Richards Inc. of Bartlett, TN, was initiated in March 1997. The original completion date for the Agreement was March 25, 1998. The purpose of this work is to develop and commercialize net shape forming methods for directly creating dense hydroxylapatite (HA) ceramic otologic implants. The project includes three tasks: (1) modification of existing gelcasting formulations to accommodate HA slurries; (2) demonstration of gelcasting to fabricate green HA ceramic components of a size and shape appropriate to otologic implants: and (3) sintering and evaluation of the HA components.

  13. Multichannel extracochlear implant.

    PubMed

    Pulec, J L; Smith, J C; Lewis, M L; Hortmann, G

    1989-03-01

    The transcutaneous eight-channel extracochlear implant has undergone continuous revision to simplify the surgical technique, to minimize patient morbidity, and to improve performance. The extracochlear electrode array has been miniaturized so that it can be inserted through the facial recess without disturbing the external auditory canal, tympanic membrane, or malleus. The use of the remote antenna placed around the external auditory canal has greatly increased battery life and patient comfort. With its simplified incisions, the surgical procedure can be performed as out-patient surgery. Preoperative cochlear nerve testing and use of evoked response cochlear nerve testing allow preadjustment of the speech processor. Current features and performance of the implant are discussed.

  14. Current trends in dental implants

    PubMed Central

    Gaviria, Laura; Salcido, John Paul; Guda, Teja

    2014-01-01

    Tooth loss is very a very common problem; therefore, the use of dental implants is also a common practice. Although research on dental implant designs, materials and techniques has increased in the past few years and is expected to expand in the future, there is still a lot of work involved in the use of better biomaterials, implant design, surface modification and functionalization of surfaces to improve the long-term outcomes of the treatment. This paper provides a brief history and evolution of dental implants. It also describes the types of implants that have been developed, and the parameters that are presently used in the design of dental implants. Finally, it describes the trends that are employed to improve dental implant surfaces, and current technologies used for the analysis and design of the implants. PMID:24868501

  15. Current trends in dental implants.

    PubMed

    Gaviria, Laura; Salcido, John Paul; Guda, Teja; Ong, Joo L

    2014-04-01

    Tooth loss is very a very common problem; therefore, the use of dental implants is also a common practice. Although research on dental implant designs, materials and techniques has increased in the past few years and is expected to expand in the future, there is still a lot of work involved in the use of better biomaterials, implant design, surface modification and functionalization of surfaces to improve the long-term outcomes of the treatment. This paper provides a brief history and evolution of dental implants. It also describes the types of implants that have been developed, and the parameters that are presently used in the design of dental implants. Finally, it describes the trends that are employed to improve dental implant surfaces, and current technologies used for the analysis and design of the implants.

  16. Ion implantation in silicate glasses

    SciTech Connect

    Arnold, G.W.

    1993-12-01

    This review examines the effects of ion implantation on the physical properties of silicate glasses, the compositional modifications that can be brought about, and the use of metal implants to form colloidal nanosize particles for increasing the nonlinear refractive index.

  17. Thermal desorption of deuterium implanted into beryllium

    SciTech Connect

    Markin, A.V.; Chernikov, V.N.; Zakharov, A.P.

    1995-09-01

    By means of TDS measurements it is shown that the desorption of deuterium from Be implanted with 5 keV D ions to fluences, {Phi}, from 1x10{sup 20} D/m{sup 2} to 1x10{sup 21} D/m{sup 2} proceeds in one high temperature stage B, while at {Phi} {ge} 1.2x10{sup 21}D/m{sup 2} one more stage A is added. The desorption maximum A is narrow and consists of two peaks A{sub 1} and A{sub 2} at about 460 K and 490 K, respectively. Peak A{sub 1} is attributed to the desorption of deuterium from the walls of opened channels formed under D ion implantation. Peak {sub A}2 is a consequence of the opening of a part of closed bubbles/channels to the outer surface. The position of maximum B shifts noticeably and nonsteadily on the fluence in a range from 850 to 1050 K. The origin of this maximum is the liberation of D atoms bound at vacancy complexes discussed previously by Wampler. The dependence of Tm(B) on the fluence is governed by the interaction of freely migrating D atoms with partly opened or fully closed gas cavity arrangements which are created under temperature ramping, but differently in specimens implanted with D ions to different fluences.

  18. Effects of Intralaminar Thalamic Stimulation on Language Functions

    ERIC Educational Resources Information Center

    Bhatnagar, Subhash C.; Mandybur, George T.

    2005-01-01

    Fifteen neurosurgical subjects, who were undergoing thalamic chronic electrode implants as a treatment for dyskinesia and chronic pain, were evaluated on a series of neurolinguistic functions to determine if the stimulation of the centromedianum nucleus of the thalamus affected language and cognitive processing. Analysis of the data revealed that…

  19. Spinal stimulator peri-electrode masses: case report.

    PubMed

    Scranton, Robert A; Skaribas, Ioannis M; Simpson, Richard K

    2015-01-01

    The authors describe a case of delayed spastic quadriparesis caused by a peri-electrode mass following the implantation of a minimally invasive percutaneous spinal cord stimulator (SCS). Prior reports with paddle-type electrodes are reviewed, and a detailed histological and pathophysiological comparison with the present case is made. The patient developed tolerance to a cervical percutaneous SCS 4 months after implantation, followed by the onset of spastic quadriparesis 9 months after implantation. The stimulator was removed, and contrast-enhanced MRI revealed an enhancing epidural mass where the system had been placed, with severe spinal cord compression. Decompression was carried out, and the patient experienced neurological improvement. Pathological examination revealed fibrotic tissue with granulomatous and multinucleated giant cell reactions. No evidence of infection or hemorrhage was found. Professionals treating patients with SCSs or contemplating their insertion should be aware of this delayed complication and associated risk factors. PMID:25380541

  20. The ruptured PIP breast implant.

    PubMed

    Helyar, V; Burke, C; McWilliams, S

    2013-08-01

    Public concern erupted about the safety of Poly Implant Prothèse (PIP) breast implants when it was revealed in 2011 that they contained an inferior, unlicensed industrial-grade silicone associated with a high rate of rupture. There followed national guidance for UK clinicians, which led to a considerable increase in referrals of asymptomatic women for breast implant assessment. In this review we discuss possible approaches to screening the PIP cohort and the salient characteristics of a ruptured implant. PMID:23622796

  1. 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.

  2. PET-imaging of brain plasticity after cochlear implantation.

    PubMed

    Strelnikov, K; Marx, M; Lagleyre, S; Fraysse, B; Deguine, O; Barone, P

    2015-04-01

    In this article, we review the PET neuroimaging literature, which indicates peculiarities of brain networks involved in speech restoration after cochlear implantation. We consider data on implanted patients during stimulation as well as during resting state, which indicates basic long-term reorganisation of brain functional architecture. On the basis of our analysis of neuroimaging literature and considering our own studies, we indicate that auditory recovery in deaf patients after cochlear implantation partly relies on visual cues. The brain develops mechanisms of audio-visual integration as a strategy to achieve high levels of speech recognition. It turns out that this neuroimaging evidence is in line with behavioural findings of better audiovisual integration in these patients. Thus, strong visually and audio-visually based rehabilitation during the first months after cochlear implantation would significantly improve and fasten the functional recovery of speech intelligibility and other auditory functions in these patients. We provide perspectives for further neuroimaging studies in cochlear implanted patients, which would help understand brain organisation to restore auditory cognitive processing in the implanted patients and would potentially suggest novel approaches for their rehabilitation. This article is part of a Special Issue entitled . PMID:25448166

  3. Forward-masked spatial tuning curves in cochlear implant users

    PubMed Central

    Nelson, David A.; Donaldson, Gail S.; Kreft, Heather

    2008-01-01

    Forward-masked psychophysical spatial tuning curves (fmSTCs) were measured in twelve cochlear-implant subjects, six using bipolar stimulation (Nucleus devices)and six using monopolar stimulation (Clarion devices). fmSTCs were measured at several probe levels on a middle electrode using a fixed-level probe stimulus and variable-level maskers. The average fmSTC slopes obtained in subjects using bipolar stimulation (3.7 dB/mm) were approximately three times steeper than average slopes obtained in subjects using monopolar stimulation (1.2 dB/mm). Average spatial bandwidths were about half as wide for subjects with bipolar stimulation (2.6 mm) than for subjects with monopolar stimulation (4.6 mm). None of the tuning curve characteristics changed significantly with probe level. fmSTCs replotted in terms of acoustic frequency, using Greenwood’s [J. Acoust. Soc. Am. 33, 1344–1356 (1961)] frequency-to-place equation, were compared with forward-masked psychophysical tuning curves obtained previously from normal-hearing and hearing-impaired acoustic listeners. The average tuning characteristics of fmSTCs in electric hearing were similar to the broad tuning observed in normal-hearing and hearing-impaired acoustic listeners at high stimulus levels. This suggests that spatial tuning is not the primary factor limiting speech perception in many cochlear implant users. PMID:18345841

  4. Peri-Implant Crestal Bone Loss: A Putative Mechanism

    PubMed Central

    Ujiie, Yuko; Todescan, Reynaldo; Davies, John E.

    2012-01-01

    Purpose. The immunological mechanisms of peri-implant crestal bone loss have, hitherto, not been elucidated. We hypothesized that bacterial products from the microgap cause upregulation of cytokines in otherwise healthy peri-implant cells, which results in osteoclast formation and, ultimately, in bone resorption. Materials and Methods. We used RT-PCR and ELISA to assay mediators of osteoclastogenesis in rat and human macrophages (r-and hMO); bone marrow derived stromal cells (r-and hBMCs); and human gingival fibroblasts (hGF)—with or without stimulation by LPS. TRAP positive multinucleate cells were assessed for their resorptive ability. Results. We show that IL-1α, IL-1β, and IL-6 were expressed by all examined cell types, and TNF-α was upregulated in hGF. Secretion of IL-1α and IL-1β proteins was stimulated in hMO by LPS, and IL-6 protein secretion was highly stimulated in hBMCs and hGF. Both LPS and RANKL stimulated macrophages to form osteoclast-like TRAP positive cells, which resorbed calcium phosphate substrates. Conclusion. Taken together, the results of our study support the hypothesis that bacterial endotoxins upregulate enhanced mediators of osteoclastogenesis in resident cells found in the healthy peri-implant compartment and that the local synergistic action of cytokines secreted by such cells results in the genesis of resorptively active osteoclasts. PMID:23091492

  5. Implantation in assisted reproduction: a look at endometrial receptivity.

    PubMed

    Fatemi, H M; Popovic-Todorovic, B

    2013-11-01

    Implantation failure in assisted reproduction is thought to be mainly due to impaired uterine receptivity. With normal uterine anatomy, changes in endocrine profile during ovarian stimulation and medical conditions of the mother (i.e. thrombophilia and abnormal immunological response) could result in a non-receptive endometrium. High oestradiol concentrations during ovarian stimulation lead to premature progesterone elevation, causing endometrial advancement and hampering implantation, which can be overcome by a freeze-all approach and embryo transfer in natural cycles or by milder stimulation protocols. Patients with recurrent implantation failure (RIF) should be tested for inherited and acquired thrombophilias. Each patient should be individually assessed and counselled regarding therapy with low-molecular-weight heparin (LMWH). Empirical treatment with LMWH, aspirin or corticosteroids is not effective for women with RIF who have negative thrombophilic tests. If thrombophilic tests are normal, patients should be tested for immunological causes. If human leukocyte antigen dissimilarity is proven, treatment with intravenous immunoglobulin might be beneficial. Preliminary observational studies using intralipid infusion in the presence of increased natural killer cytotoxic activity are interesting but the proposed rationale is controversial and randomized controlled trials are needed. Hysteroscopy and/or endometrial scratching in the cycle preceding ovarian stimulation should become standard for patients with RIF.

  6. Magnetic resonance imaging safety of deep brain stimulator devices.

    PubMed

    Oluigbo, Chima O; Rezai, Ali R

    2013-01-01

    Magnetic resonance imaging (MRI) has become the standard of care for the evaluation of different neurological disorders of the brain and spinal cord due to its multiplanar capabilities and excellent soft tissue resolution. With the large and increasing population of patients with implanted deep brain stimulation (DBS) devices, a significant proportion of these patients with chronic neurological diseases require evaluation of their primary neurological disease processes by MRI. The presence of an implanted DBS device in a magnetic resonance environment presents potential hazards. These include the potential for induction of electrical currents or heating in DBS devices, which can result in neurological tissue injury, magnetic field-induced device migration, or disruption of the operational aspects of the devices. In this chapter, we review the basic physics of potential interactions of the MRI environment with implanted DBS devices, summarize results from phantom studies and clinical series, and discuss present recommendations for safe MRI in patients with implanted DBS devices.

  7. Magnetic resonance imaging safety of deep brain stimulator devices.

    PubMed

    Oluigbo, Chima O; Rezai, Ali R

    2013-01-01

    Magnetic resonance imaging (MRI) has become the standard of care for the evaluation of different neurological disorders of the brain and spinal cord due to its multiplanar capabilities and excellent soft tissue resolution. With the large and increasing population of patients with implanted deep brain stimulation (DBS) devices, a significant proportion of these patients with chronic neurological diseases require evaluation of their primary neurological disease processes by MRI. The presence of an implanted DBS device in a magnetic resonance environment presents potential hazards. These include the potential for induction of electrical currents or heating in DBS devices, which can result in neurological tissue injury, magnetic field-induced device migration, or disruption of the operational aspects of the devices. In this chapter, we review the basic physics of potential interactions of the MRI environment with implanted DBS devices, summarize results from phantom studies and clinical series, and discuss present recommendations for safe MRI in patients with implanted DBS devices. PMID:24112886

  8. Dual Positive Regulation of Embryo Implantation by Endocrine and Immune Systems--Step-by-Step Maternal Recognition of the Developing Embryo.

    PubMed

    Fujiwara, Hiroshi; Araki, Yoshihiko; Imakawa, Kazuhiko; Saito, Shigeru; Daikoku, Takiko; Shigeta, Minoru; Kanzaki, Hideharu; Mori, Takahide

    2016-03-01

    In humans, HCG secreted from the implanting embryo stimulates progesterone production of the corpus luteum to maintain embryo implantation. Along with this endocrine system, current evidence suggests that the maternal immune system positively contributes to the embryo implantation. In mice, immune cells that have been sensitized with seminal fluid and then the developing embryo induce endometrial differentiation and promote embryo implantation. After hatching, HCG activates regulatory T and B cells through LH/HCG receptors and then stimulates uterine NK cells and monocytes through sugar chain receptors, to promote and maintain pregnancy. In accordance with the above, the intrauterine administration of HCG-treated PBMC was demonstrated to improve implantation rates in women with repeated implantation failures. These findings suggest that the maternal immune system undergoes functional changes by recognizing the developing embryos in a stepwise manner even from a pre-fertilization stage and facilitates embryo implantation in cooperation with the endocrine system. PMID:26755274

  9. Noise from implantable Cooper cable.

    PubMed

    Carrington, V; Zhou, L; Donaldson, N

    2005-09-01

    Cooper cable is made for implanted devices, usually for connection to stimulating electrodes. An experiment has been performed to see whether these cables would be satisfactory for recording electroneurogram (ENG) signals from cuffs. Four cables were subjected to continuous flexion at 2 Hz while submerged in saline. The cables were connected to a low-noise amplifier, and the noise was measured using a spectrum analyser. These cables had not fractured after 184 million flexions, and the noise in the neural band (500-5000 Hz) had not increased owing to age. Noise in the ENG band increased by less than 3 dB owing to the motion. A fifth, worn cable did fail during the experiment, the conductors becoming exposed to the saline, but this was only apparent by extra noise when the cable was in motion. After 184 million flexions, the four cables were given a more severe test: instead of being connected to the amplifier reference node, two of the four cores of each cable were connected to 18V batteries. Two of the cables were then noisier, but only when in motion, presumably because of leakage between cores. Cooper cables are excellent for transmitting neural signals alone; transmission in one cable of neural signals and power supplies should be avoided if possible. PMID:16411634

  10. Semiconductor Ion Implanters

    NASA Astrophysics Data System (ADS)

    MacKinnon, Barry A.; Ruffell, John P.

    2011-06-01

    In 1953 the Raytheon CK722 transistor was priced at 7.60. Based upon this, an Intel Xeon Quad Core processor containing 820,000,000 transistors should list at 6.2 billion! Particle accelerator technology plays an important part in the remarkable story of why that Intel product can be purchased today for a few hundred dollars. Most people of the mid twentieth century would be astonished at the ubiquity of semiconductors in the products we now buy and use every day. Though relatively expensive in the nineteen fifties they now exist in a wide range of items from high-end multicore microprocessors like the Intel product to disposable items containing `only' hundreds or thousands like RFID chips and talking greeting cards. This historical development has been fueled by continuous advancement of the several individual technologies involved in the production of semiconductor devices including Ion Implantation and the charged particle beamlines at the heart of implant machines. In the course of its 40 year development, the worldwide implanter industry has reached annual sales levels around 2B, installed thousands of dedicated machines and directly employs thousands of workers. It represents in all these measures, as much and possibly more than any other industrial application of particle accelerator technology. This presentation discusses the history of implanter development. It touches on some of the people involved and on some of the developmental changes and challenges imposed as the requirements of the semiconductor industry evolved.

  11. Elementary Implantable Force Sensor

    PubMed Central

    Wachs, Rebecca A.; Ellstein, David; Drazan, John; Healey, Colleen P.; Uhl, Richard L.; Connor, Kenneth A.

    2014-01-01

    Implementing implantable sensors which are robust enough to maintain long term functionality inside the body remains a significant challenge. The ideal implantable sensing system is one which is simple and robust; free from batteries, telemetry, and complex electronics. We have developed an elementary implantable sensor for orthopaedic smart implants. The sensor requires no telemetry and no batteries to communicate wirelessly. It has no on-board signal conditioning electronics. The sensor itself has no electrical connections and thus does not require a hermetic package. The sensor is an elementary L-C resonator which can function as a simple force transducer by using a solid dielectric material of known stiffness between two parallel Archimedean coils. The operating characteristics of the sensors are predicted using a simplified, lumped circuit model. We have demonstrated sensor functionality both in air and in saline. Our preliminary data indicate that the sensor can be reasonably well modeled as a lumped circuit to predict its response to loading. PMID:24883335

  12. Semiconductor Ion Implanters

    SciTech Connect

    MacKinnon, Barry A.; Ruffell, John P.

    2011-06-01

    In 1953 the Raytheon CK722 transistor was priced at $7.60. Based upon this, an Intel Xeon Quad Core processor containing 820,000,000 transistors should list at $6.2 billion. Particle accelerator technology plays an important part in the remarkable story of why that Intel product can be purchased today for a few hundred dollars. Most people of the mid twentieth century would be astonished at the ubiquity of semiconductors in the products we now buy and use every day. Though relatively expensive in the nineteen fifties they now exist in a wide range of items from high-end multicore microprocessors like the Intel product to disposable items containing 'only' hundreds or thousands like RFID chips and talking greeting cards. This historical development has been fueled by continuous advancement of the several individual technologies involved in the production of semiconductor devices including Ion Implantation and the charged particle beamlines at the heart of implant machines. In the course of its 40 year development, the worldwide implanter industry has reached annual sales levels around $2B, installed thousands of dedicated machines and directly employs thousands of workers. It represents in all these measures, as much and possibly more than any other industrial application of particle accelerator technology. This presentation discusses the history of implanter development. It touches on some of the people involved and on some of the developmental changes and challenges imposed as the requirements of the semiconductor industry evolved.

  13. Remote actuated valve implant

    DOEpatents

    McKnight, Timothy E.; Johnson, Anthony; Moise, Kenneth J.; Ericson, Milton Nance; Baba, Justin S.; Wilgen, John B.; Evans, Boyd Mccutchen

    2016-05-10

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  14. Ion implantation in polymers

    NASA Astrophysics Data System (ADS)

    Wintersgill, M. C.

    1984-02-01

    An introductory overview will be given of the effects of ion implantation on polymers, and certain areas will be examined in more detail. Radiation effects in general and ion implantation in particular, in the field of polymers, present a number of contrasts with those in ionic crystals, the most obvious difference being that the chemical effects of both the implanted species and the energy transfer to the host may profoundly change the nature of the target material. Common effects include crosslinking and scission of polymer chains, gas evolution, double bond formation and the formation of additional free radicals. Research has spanned the chemical processes involved, including polymerization reactions achievable only with the use of radiation, to applied research dealing both with the effects of radiation on polymers already in commercial use and the tailoring of new materials to specific applications. Polymers are commonly divided into two groups, in describing their behavior under irradiation. Group I includes materials which form crosslinks between molecules, whereas Group II materials tend to degrade. In basic research, interest has centered on Group I materials and of these polyethylene has been studied most intensively. Applied materials research has investigated a variety of polymers, particularly those used in cable insulation, and those utilized in ion beam lithography of etch masks. Currently there is also great interest in enhancing the conducting properties of polymers, and these uses would tend to involve the doping capabilities of ion implantation, rather than the energy deposition.

  15. Peritoneal trophoblastic implant.

    PubMed

    Rachagan, S P; Kutty, K; Govindan, K S

    1997-09-01

    A case of persistent trophoblastic tissue on the pelvic peritoneum is presented. While most cases are secondary to conservative surgery for tubal ectopic pregnancy, primary implantation can also occur as highlighted by this case. A brief pathophysiology of the condition is presented. The importance of monitoring the serum for beta subunit human chorionic gonadotrophin (HCG) is emphasised.

  16. Implantable Drug Dispenser

    NASA Technical Reports Server (NTRS)

    Collins, E. R. J.

    1983-01-01

    Drugs such as insulin are injected as needed directly into bloodstream by compact implantable dispensing unit. Two vapor cavities produce opposing forces on drug-chamber diaphragm. Heaters in cavities allow control of direction and rate of motion of bellows. Dispensing capsule fitted with coil so batteries can be recharged by induction.

  17. Remote actuated valve implant

    DOEpatents

    McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

    2014-02-25

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  18. Implantable Impedance Plethysmography

    PubMed Central

    Theodor, Michael; Ruh, Dominic; Ocker, Martin; Spether, Dominik; Förster, Katharina; Heilmann, Claudia; Beyersdorf, Friedhelm; Manoli, Yiannos; Zappe, Hans; Seifert, Andreas

    2014-01-01

    We demonstrate by theory, as well as by ex vivo and in vivo measurements that impedance plethysmography, applied extravascularly directly on large arteries, is a viable method for monitoring various cardiovascular parameters, such as blood pressure, with high accuracy. The sensor is designed as an implant to monitor cardiac events and arteriosclerotic progression over the long term. PMID:25123467

  19. Auditory Implant Research at the House Ear Institute 1989–2013

    PubMed Central

    Shannon, Robert V.

    2014-01-01

    The House Ear Institute (HEI) had a long and distinguished history of auditory implant innovation and development. Early clinical innovations include being one of the first cochlear implant (CI) centers, being the first center to implant a child with a cochlear implant in the US, developing the auditory brainstem implant, and developing multiple surgical approaches and tools for Otology. This paper reviews the second stage of auditory implant research at House – in-depth basic research on perceptual capabilities and signal processing for both cochlear implants and auditory brainstem implants. Psychophysical studies characterized the loudness and temporal perceptual properties of electrical stimulation as a function of electrical parameters. Speech studies with the noise-band vocoder showed that only four bands of tonotopically arrayed information were sufficient for speech recognition, and that most implant users were receiving the equivalent of 8–10 bands of information. The noise-band vocoder allowed us to evaluate the effects of the manipulation of the number of bands, the alignment of the bands with the original tonotopic map, and distortions in the tonotopic mapping, including holes in the neural representation. Stimulation pulse rate was shown to have only a small effect on speech recognition. Electric fields were manipulated in position and sharpness, showing the potential benefit of improved tonotopic selectivity. Auditory training shows great promise for improving speech recognition for all patients. And the Auditory Brainstem Implant was developed and improved and its application expanded to new populations. Overall, the last 25 years of research at HEI helped increase the basic scientific understanding of electrical stimulation of hearing and contributed to the improved outcomes for patients with the CI and ABI devices. PMID:25449009

  20. The reverse zygomatic implant: a new implant for maxillofacial reconstruction.

    PubMed

    Dawood, Andrew; Collier, Jonathan; Darwood, Alastair; Tanner, Susan

    2015-01-01

    This case report describes the rehabilitation of a patient who had been treated with a hemimaxillectomy, reconstruction with a latissimus dorsi vascularized free flap, and radiotherapy for carcinoma of the sinus some years previously. Limited jaw opening, difficult access through the flap to the bony site, and the very small amount of bone available in which to anchor the implant inspired the development and use of a new "reverse zygomatic" implant. For this treatment, site preparation and implant insertion were accomplished using an extraoral approach. The implant was used along with two other conventional zygomatic implants to provide support for a milled titanium bar and overdenture to rehabilitate the maxilla. Two years later, the patient continues to enjoy a healthy reconstruction. The reverse zygomatic implant appears to show promise as a useful addition to the implant armamentarium for the treatment of the patient undergoing maxillectomy. PMID:26574864