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Sample records for motor evoked potential

  1. [Motor evoked potentials in thoracoabdominal aortic surgery].

    PubMed

    Magro, Cátia; Nora, David; Marques, Miguel; Alves, Angela Garcia

    2012-01-01

    Thoracoabdominal aortic disease (aneurysm or dissection) has increased in recent decades. Surgery is the curative treatment but is associated to high perioperative morbidity and mortality risks. Paraplegia is one of the most severe complications, whose incidence has decreased significantly with the implementation of spinal cord protection strategies. No single method or combination of methods has proven to be fully effective in preventing paraplegia. This review is intended to analyse the scientific evidence available on the role of intraoperative monitoring with motor evoked potentials in the neurological outcome of patients undergoing thoracoabdominal aortic surgery. An online search (PubMed) was conducted. Relevant references were selected and reviewed. Intraoperative monitoring with motor evoked potentials (MEP) allows early detection of ischemic events and a targeted intervention to prevent the development of spinal cord injury, significantly reducing the incidence of postoperative paraplegia. MEP monitoring may undergo several intraoperative interferences which may compromise their interpretation. Neuromuscular blockade is the main limiting factor of anesthetic origin. It is essential to strike a balance between monitoring conditions and surgical and anesthetic needs as well as to evaluate the risks and benefits of the technique for each patient. MEP monitoring improves neurological outcome when integrated in a multidisciplinary strategy which must include multiple protective mechanisms that should be tailored to each hospital reality.

  2. Alterations of motor evoked potentials by thalamotomy.

    PubMed

    van der Linden, C; Bruggeman, R; Goldman, W H

    1993-09-01

    To evaluate the effect of stereotactic thalamotomy on the function of the corticospinal tract, we studied motor evoked potentials (MEPs) recorded by surface electromyography (EMG) in the left extensor carpi radialis (ECR) and flexor carpi radialis (FCR) with magnetic stimulation of the contralateral motor cortex in a 43-year-old patient with a severe postural and resting tremor of the left hand. The patient was diagnosed eight years previously with left hemiparkinsonism. The tremor was unresponsive to various medications. After thalamotomy the tremor had disappeared, confirmed by EMG studies. MEP latencies at rest were normal and did not change after thalamotomy. Volitional contraction of either ECR or FCR shortened the latency of the corresponding MEP before and after thalamotomy. However, before thalamotomy responses at rest were less well synchronized and followed by EMG silence with subsequent long duration tonic after discharges. Furthermore, during voluntary contraction the responses only slightly enhanced. After surgery MEPs at rest in both muscles were more synchronized and after-discharges had disappeared. Moreover, with volitional contraction of either ECR of FCR, the MEPs enhanced more dramatically. The silent periods (SPs) following the MEP during sustained voluntary contraction were longer after thalamotomy. The consistent MEP latencies suggest that the conduction of the pyramidal tract is unaffected by thalamotomy. The better synchronized responses, the alleviation of after-discharges and the longer SPs in this patient with hemiparkinsonism following thalamotomy suggest an improved sensorimotor integration, which may be the result of a reduced thalamic input onto suprasegmental levels.

  3. Poisson distribution to analyze near-threshold motor evoked potentials.

    PubMed

    Kaelin-Lang, Alain; Conforto, Adriana B; Z'Graggen, Werner; Hess, Christian W

    2010-11-01

    Motor unit action potentials (MUAPs) evoked by repetitive, low-intensity transcranial magnetic stimulation can be modeled as a Poisson process. A mathematical consequence of such a model is that the ratio of the variance to the mean of the amplitudes of motor evoked potentials (MEPs) should provide an estimate of the mean size of the individual MUAPs that summate to generate each MEP. We found that this is, in fact, the case. Our finding thus supports the use of the Poisson distribution to model MEP generation and indicates that this model enables characterization of the motor unit population that contributes to near-threshold MEPs.

  4. Statistical model applied to motor evoked potentials analysis.

    PubMed

    Ma, Ying; Thakor, Nitish V; Jia, Xiaofeng

    2011-01-01

    Motor evoked potentials (MEPs) convey information regarding the functional integrity of the descending motor pathways. Absence of the MEP has been used as a neurophysiological marker to suggest cortico-spinal abnormalities in the operating room. Due to their high variability and sensitivity, detailed quantitative studies of MEPs are lacking. This paper applies a statistical method to characterize MEPs by estimating the number of motor units and single motor unit potential amplitudes. A clearly increasing trend of single motor unit potential amplitudes in the MEPs after each pulse of the stimulation pulse train is revealed by this method. This statistical method eliminates the effects of anesthesia, and provides an objective assessment of MEPs. Consequently this statistical method has high potential to be useful in future quantitative MEPs analysis.

  5. Motor evoked potentials in thoracoabdominal aortic surgery: CON.

    PubMed

    Coselli, Joseph S; Tsai, Peter I

    2010-05-01

    Thoracoabdominal aortic aneurysms (TAAAs) have a dismal natural history that frequently necessitates surgical repair, but such repairs sometimes result in paraplegia and paraparesis. To reduce the risk of these complications, intraoperative monitoring of spinal cord motor evoked potentials (MEPs) can be used to guide TAAA repair procedures and may potentially minimize spinal cord ischemia. However, the use of MEP monitoring techniques requires important changes to anesthetic management, entails certain risks, and has important contraindications.

  6. Intraoperative Monitoring: Recent Advances in Motor Evoked Potentials.

    PubMed

    Koht, Antoun; Sloan, Tod B

    2016-09-01

    Advances in electrophysiological monitoring have improved the ability of surgeons to make decisions and minimize the risks of complications during surgery and interventional procedures when the central nervous system (CNS) is at risk. Individual techniques have become important for identifying or mapping the location and pathway of critical neural structures. These techniques are also used to monitor the progress of procedures to augment surgical and physiologic management so as to reduce the risk of CNS injury. Advances in motor evoked potentials have facilitated mapping and monitoring of the motor tracts in newer, more complex procedures. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Transesophageal versus transcranial motor evoked potentials to monitor spinal cord ischemia.

    PubMed

    Tsuda, Kazumasa; Shiiya, Norihiko; Takahashi, Daisuke; Ohkura, Kazuhiro; Yamashita, Katsushi; Kando, Yumi; Arai, Yoshifumi

    2016-02-01

    We have previously reported that transesophageal motor evoked potential is feasible and more stable than transcranial motor evoked potential. This study aimed to investigate the efficacy of transesophageal motor evoked potential to monitor spinal cord ischemia. Transesophageal and transcranial motor evoked potentials were recorded in 13 anesthetized dogs at the bilateral forelimbs, anal sphincters, and hindlimbs. Spinal cord ischemia was induced by aortic balloon occlusion at the 8th to 10th thoracic vertebra level. In the 12 animals with motor evoked potential disappearance, occlusion was maintained for 10 minutes (n = 6) or 40 minutes (n = 6) after motor evoked potential disappearance. Neurologic function was evaluated by Tarlov score at 24 and 48 hours postoperatively. Time to disappearance of bilateral motor evoked potentials was quicker in transesophageal motor evoked potentials than in transcranial motor evoked potentials at anal sphincters (6.9 ± 3.1 minutes vs 8.3 ± 3.4 minutes, P = .02) and hindlimbs (5.7 ± 1.9 minutes vs 7.1 ± 2.7 minutes, P = .008). Hindlimb function was normal in all dogs in the 10-minute occlusion group, and motor evoked potentials recovery (>75% on both sides) after reperfusion was quicker in transesophageal motor evoked potentials than transcranial motor evoked potentials at hindlimbs (14.8 ± 5.6 minutes vs 24.7 ± 8.2 minutes, P = .001). At anal sphincters, transesophageal motor evoked potentials always reappeared (>25%), but transcranial motor evoked potentials did not in 3 of 6 dogs. In the 40-minute occlusion group, hindlimb motor evoked potentials did not reappear in 4 dogs with paraplegia. Among the 2 remaining dogs, 1 with paraparesis (Tarlov 3) showed delayed recovery (>75%) of hindlimb motor evoked potentials without reappearance of anal sphincter motor evoked potentials. In another dog with spastic paraplegia, transesophageal motor evoked potentials from the hindlimbs remained less than 20%, whereas transcranial motor

  8. Comparison of Transcranial Motor Evoked Potentials and Somatosensory Evoked Potentials During Thoracoabdominal Aortic Aneurysm Repair

    PubMed Central

    Meylaerts, Sven A.; Jacobs, Michael J.; van Iterson, Vincent; De Haan, Peter; Kalkman, Cor J.

    1999-01-01

    Objective To compare transcranial motor evoked potentials (tc-MEPs) and somatosensory evoked potentials (SSEPs) as indicators of spinal cord function during thoracoabdominal aortic aneurysm repair. Summary Background Data Somatosensory evoked potentials reflect conduction in dorsal columns. tc-MEPs represent anterior horn motor neuron function. This is the first study to compare the techniques directly during thoracoabdominal aortic aneurysm repair. Methods In 38 patients, thoracoabdominal aortic aneurysm repair (type I, n = 10, type II, n = 14, type III, n = 6, type IV, n = 8) was performed using left heart bypass and segmental artery reimplantation. tc-MEP amplitudes <25% and SSEP amplitudes <50% and/or latencies >110% were considered indicators of cord ischemia. The authors compared the response of both methods to interventions and correlated the responses at the end of surgery to neurologic outcomes. Results Ischemic tc-MEP changes occurred in 18/38 patients and could be restored by segmental artery reperfusion (n = 12) or by increasing blood pressure (n = 6). Significant SSEP changes accompanied these tc-MEP events in only 5/18 patients, with a delay of 2 to 34 minutes. SSEPs recovered in only two patients. In another 11 patients, SSEP amplitudes fell progressively to <50% of control without parallel tc-MEP changes or association with cross-clamp events or pressure decreases. At the end of the procedure, tc-MEP amplitudes were 84 ± 46% of control. In contrast, SSEP amplitudes were <50% of control in 15 patients (39%). No paraplegia occurred. Conclusion In all patients, tc-MEP events could be corrected by applying protective strategies. No patient awoke paraplegic. SSEPs showed delayed ischemia detection and a high rate of false-positive results. PMID:10615928

  9. N10 potential as an antidromic motor evoked potential in a median nerve short-latency somatosensory evoked potential study.

    PubMed

    Inoue, Ken; Mimori, Yasuyo; Nakamura, Shigenobu

    2002-01-01

    When stimulating the mixed nerve to record evoked potential, both sensory and motor fibers are activated before entering the spinal cord. The N10 potential has been described as an antidromic motor evoked potential based on results obtained by recording at the anterior midneck. In the present study, we examined the changes in latencies of Erb's potential, N10, and N13 by stimulating the median nerve distally at the wrist and proximally at the elbow. The conduction velocity of N10 calculated by the difference between N10 latencies at the two stimulation points was consistent with motor conduction velocity, although N13 conduction velocity estimated by the same method reflected a sensory conduction velocity. A positive relation was also observed between the indirect latency from the stimulation point to the anterior root as calculated using the equation (F - M - 1) / 2 (ms) and the direct latency to the negative peak of the N10 potential. Our data support the notion that N10 represents antidromic motor potential originating in the spinal entry zone of the anterior root.

  10. Motor evoked potentials in unilateral lingual paralysis after monohemispheric ischaemia

    PubMed Central

    Muellbacher, W.; Artner, C.; Mamoli, B.

    1998-01-01

    OBJECTIVES—The occurrence of a lingual paralysis after unilateral upper motor neuron lesions is an infrequent clinical phenomenon, and the underlying pathophysiological mechanisms are poorly understood. We studied the cortical motor representations of ipsilateral and contralateral lingual muscles in healthy controls and in a selected group of stroke patients, to clarify the variable occurrence of a lingual paralysis after recent monohemispheric ischaemia.
METHODS—A special bipolar surface electrode was used to record the ipsilateral and contralateral compound muscle action potentials (CMAPs) from the lingual muscles after transcranial magnetic stimulation (TMS) of the human motor cortex and peripheral electrical stimulation (PES) of the hypoglossal nerve medial to the angle of the jaw. Four patients with a lingual paralysis (group 1) and four patients with symmetric lingual movements (group 2) after monohemispheric first ever stroke were studied and compared with 40 healthy controls.
RESULTS—In controls, TMS of either hemisphere invariably produces CAMPs in the ipsilateral and contralateral lingual muscles, elicited through crossed and uncrossed central motor pathways, respectively. In the 40 healthy controls, TMS of either hemisphere elicited CMAPs of significantly greater amplitudes and shorter onset latencies from the contralateral muscles compared with the ipsilateral responses (p<0.0001). In the patient groups, TMS of the affected hemisphere failed to evoke any CMAP from either lingual side; TMS of the unsevered hemisphere always produced normal ipsilateral and contralateral responses, irrespective of whether the ipsilateral muscles were paralysed or not.
CONCLUSIONS—Bilateral crossed and uncrossed corticonuclear projections are invariably existent in humans. After unilateral interruption of these pathways, some people do exhibit a lingual paralysis whereas others do not. The development of a central lingual paralysis is most likely dependent on

  11. Motor evoked potentials enable differentiation between motor and sensory branches of peripheral nerves in animal experiments.

    PubMed

    Turkof, Edvin; Jurasch, Nikita; Knolle, Erik; Schwendenwein, Ilse; Habib, Danja; Unger, Ewald; Reichel, Martin; Losert, Udo

    2006-10-01

    Differentiation between motor and sensory fascicles is frequently necessary in reconstructive peripheral nerve surgery. The goal of this experimental study was to verify if centrally motor evoked potentials (MEP) could be implemented to differentiate sensory from motor fascicles, despite the well-known intermingling between nerve fascicles along their course to their distant periphery. This new procedure would enable surgeons to use MEP for placing nerve grafts at corresponding fascicles in the proximal and distal stumps without the need to use time-consuming staining. In ten sheep, both ulnar nerves were exposed at the terminal bifurcation between the last sensory and motor branch. Animals were then relaxed to avoid volume conduction. On central stimulation, the evoked nerve compound action potentials were simultaneously recorded from both terminal branches. In all cases, neurogenic motor nerve action potentials were recorded only from the terminal motor branch. The conclusion was that MEPs can be used for intraoperative differentiation between sensory and motor nerves. Further studies are necessary to develop this method for in situ measurements on intact nerve trunks.

  12. Motor evoked potentials of the respiratory muscles in tetraplegic patients.

    PubMed

    Lissens, M A; Vanderstraeten, G G

    1996-11-01

    We studied the respiratory muscles with magnetic transcranial stimulation (TCS) in four spinal cord injured (SCI) patients as compared to age-matched controls from a database of 40 healthy subjects. These SCI patients all had spinal cord lesions above C6 level with a clinically incomplete tetraplegia. One patient was artificially ventilated. Motor evoked potentials (MEPs) were recorded from the diaphragm, the scalenes, the parasternal intercostals and the expiratory rectus abdominis during inspiration and expiration. In patients with incomplete tetraplegia MEP latency times were significantly prolonged in the scalenes and the parasternal intercostals, both during inspiration and expiration, and were nearly normal for the diaphragm, which was found to be more or less preserved. The mean MEP amplitudes in these patients for all inspiratory muscles studied were significantly decreased in tetraplegic patients, in part due to a decreased number of innervating axons and muscle hypotrophy. No MEPs could be obtained from the abdominal muscles, except in one C3 tetraplegic patient, in whom only a very small response was seen during expiration, with a very delayed latency time. The much lower location of their innervating nerve roots (T10) and the much longer distance of their spinal exit zone from the level of injury at the cervical spinal cord might at least partially explain this phenomenon. In the ventilator-dependent tetraplegic patient no MEPs could be obtained from any of the muscles studied. Thus, magnetic TCS is a painless and easily applicable technique to investigate the central motor conduction properties of the respiratory muscles, both in healthy humans and in tetraplegic patients.

  13. Age and gender effects on submental motor-evoked potentials.

    PubMed

    Sella, Oshrat; Jones, Richard D; Huckabee, Maggie-Lee

    2014-01-01

    It is not known whether there are age- and/or gender-related differences in magnitude of motor-evoked potentials (MEPs) of the submental muscles. Knowledge of this is important in investigations of neurophysiological aspects of swallowing. Forty healthy participants (20 males, 20 females; 20 young [21-35 years], 20 old [53-88 years]) were recruited. Surface electromyography (EMG) electrodes were placed at midline underlying the submental muscle group. Age- and gender-related differences were evaluated in two neurophysiologic measures of swallowing: MEPs stimulated by single-pulse transcranial magnetic stimulation (TMS) over the motor cortex and surface electromyography (sEMG) recorded from the same submental muscle group during non-stimulated swallows. The older participants had larger MEPs during saliva swallowing than the young participants (p = 0.04, d = 0.86). Conversely, the older participants had lower amplitude submental EMG activity during non-stimulated swallows (p = 0.045, d = 0.67). Gender had no significant effect on MEP magnitude and on submental activity during saliva swallowing. There were no effects of age or gender on MEP latencies. These findings suggest deterioration in muscle function with age in a sample of healthy adults presenting with functional swallowing. We speculate that muscular decline is partially ameliorated by increased cortical activity-i.e., increased submental MEPs-so as to preserve swallowing function in healthy older subjects. These findings emphasize the need for different reference points for evaluation of submental MEPs of different age groups.

  14. Methodology of motor evoked potentials in a rabbit model.

    PubMed

    Waterford, Stephen D; Rastegar, Michelle; Goodwin, Erin; Lapchak, Paul A; Juan, Viviana; Haji, Farnaz; Bombien, René; Khoynezhad, Ali

    2015-10-01

    Spinal cord ischemia (SCI) is a devastating complication of aortic operations. Neuromonitoring using motor evoked potentials (MEPs) is a sensitive modality to detect SCI in humans. We describe a leporine SCI model using MEPs to test pharmaceutical therapeutics and other neuroprotective adjuncts. In 80 rabbits, methods to obtain MEPs in normotensive and ischemic rabbits were developed. The effects of isoflurane, propofol, apnea, and hypotension on lower extremity MEPs were studied. Lower extremity MEPs disappear upon SCI induction in 78 of 78 (100 %) rabbits. Prior to SCI induction and during apneic episodes, lower extremity MEPs were lost in all (100 %) and upper extremity MEPs in one (25 %). Isoflurane was used in four experiments, with loss of lower extremity MEPs in all four (100 %) and loss of upper extremity MEPs in zero. With propofol upper extremity, MEPs were obtainable in 80 of 80 rabbits (100 %) and lower extremity MEPs in 78 of 80 rabbits (97.5 %) prior to SCI induction. The presence of these lower extremity MEPs prior to SCI induction was not correlated with systolic or diastolic blood pressure. Disappearance of MEPs occurred in all 45 rabbits with postoperative lower extremity impairment. MEPs in the leporine model correlate closely with paraplegia. MEPs are influenced by inhaled anesthetics and apnea but not by hypotension alone. Propofol anesthesia provides reliable MEPs. This study provides the basis for a reproducible model of SCI to be used for novel therapeutic drug development.

  15. Conditioning effect of transcranial magnetic stimulation evoking motor-evoked potential on V-wave response.

    PubMed

    Grosprêtre, Sidney; Martin, Alain

    2014-12-01

    The aim of this study was to examine the collision responsible for the volitional V-wave evoked by supramaximal electrical stimulation of the motor nerve during voluntary contraction. V-wave was conditioned by transcranial magnetic stimulation (TMS) over the motor cortex at several inter-stimuli intervals (ISI) during weak voluntary plantar flexions (n = 10) and at rest for flexor carpi radialis muscle (FCR; n = 6). Conditioning stimulations were induced by TMS with intensity eliciting maximal motor-evoked potential (MEPmax). ISIs used were ranging from -20 to +20 msec depending on muscles tested. The results showed that, for triceps surae muscles, conditioning TMS increased the V-wave amplitude (~ +250%) and the associated mechanical response (~ +30%) during weak voluntary plantar flexion (10% of the maximal voluntary contraction -MVC) for ISIs ranging from +6 to +18 msec. Similar effect was observed at rest for the FCR with ISI ranging from +6 to +12 msec. When the level of force was increased from 10 to 50% MVC or the conditioning TMS intensity was reduced to elicit responses of 50% of MEPmax, a significant decrease in the conditioned V-wave amplitude was observed for the triceps surae muscles, linearly correlated to the changes in MEP amplitude. The slope of this correlation, as well as the electro-mechanical efficiency, was closed to the identity line, indicating that V-wave impact at muscle level seems to be similar to the impact of cortical stimulation. All these results suggest that change in V-wave amplitude is a great index to reflect changes in cortical neural drive addressed to spinal motoneurons.

  16. Training voluntary motor suppression with real-time feedback of motor evoked potentials.

    PubMed

    Majid, D S Adnan; Lewis, Christina; Aron, Adam R

    2015-05-01

    Training people to suppress motor representations voluntarily could improve response control. We evaluated a novel training procedure of real-time feedback of motor evoked potentials (MEPs) generated by transcranial magnetic stimulation (TMS) over motor cortex. On each trial, a cue instructed participants to use a mental strategy to suppress a particular finger representation without overt movement. A single pulse of TMS was delivered over motor cortex, and an MEP-derived measure of hand motor excitability was delivered visually to the participant within 500 ms. In experiment 1, we showed that participants learned to reduce the excitability of a particular finger beneath baseline (selective motor suppression) within 30 min of practice. In experiment 2, we performed a double-blind study with 2 training groups (1 with veridical feedback and 1 with matched sham feedback) to show that selective motor suppression depends on the veridical feedback itself. Experiment 3 further demonstrated the importance of veridical feedback by showing that selective motor suppression did not arise from mere mental imagery, even when incentivized with reward. Thus participants can use real-time feedback of TMS-induced MEPs to discover an effective mental strategy for selective motor suppression. This high-temporal-resolution, trial-by-trial-feedback training method could be used to help people better control response tendencies and may serve as a potential therapy for motor disorders such as Tourette's and dystonia. Copyright © 2015 the American Physiological Society.

  17. Intraoperative changes in transcranial motor evoked potentials and somatosensory evoked potentials predicting outcome in children with intramedullary spinal cord tumors

    PubMed Central

    Cheng, Jason S.; Ivan, Michael E.; Stapleton, Christopher J.; Quinones-HinoJosa, AlfreDo; Gupta, Nalin; Auguste, Kurtis I.

    2015-01-01

    Object Intraoperative dorsal column mapping, transcranial motor evoked potentials (TcMEPs), and somatosensory evoked potentials (SSEPs) have been used in adults to assist with the resection of intramedullary spinal cord tumors (IMSCTs) and to predict postoperative motor deficits. The authors sought to determine whether changes in MEP and SSEP waveforms would similarly predict postoperative motor deficits in children. Methods The authors reviewed charts and intraoperative records for children who had undergone resection for IMSCTs as well as dorsal column mapping and TcMEP and SSEP monitoring. Motor evoked potential data were supplemented with electromyography data obtained using a Kartush microstimulator (Medtronic Inc.). Motor strength was graded using the Medical Research Council (MRC) scale during the preoperative, immediate postoperative, and follow-up periods. Reductions in SSEPs were documented after mechanical traction, in response to maneuvers with the cavitational ultrasonic surgical aspirator (CUSA), or both. Results Data from 12 patients were analyzed. Three lesions were encountered in the cervical and 7 in the thoracic spinal cord. Two patients had lesions of the cervicomedullary junction and upper spinal cord. Intraoperative MEP changes were noted in half of the patients. In these cases, normal polyphasic signals converted to biphasic signals, and these changes correlated with a loss of 1–2 grades in motor strength. One patient lost MEP signals completely and recovered strength to MRC Grade 4/5. The 2 patients with high cervical lesions showed neither intraoperative MEP changes nor motor deficits postoperatively. Dorsal columns were mapped in 7 patients, and the midline was determined accurately in all 7. Somatosensory evoked potentials were decreased in 7 patients. Two patients each had 2 SSEP decreases in response to traction intraoperatively but had no new sensory findings postoperatively. Another 2 patients had 3 traction-related SSEP decreases

  18. Intraoperative changes in transcranial motor evoked potentials and somatosensory evoked potentials predicting outcome in children with intramedullary spinal cord tumors.

    PubMed

    Cheng, Jason S; Ivan, Michael E; Stapleton, Christopher J; Quinones-Hinojosa, Alfredo; Gupta, Nalin; Auguste, Kurtis I

    2014-06-01

    Intraoperative dorsal column mapping, transcranial motor evoked potentials (TcMEPs), and somatosensory evoked potentials (SSEPs) have been used in adults to assist with the resection of intramedullary spinal cord tumors (IMSCTs) and to predict postoperative motor deficits. The authors sought to determine whether changes in MEP and SSEP waveforms would similarly predict postoperative motor deficits in children. The authors reviewed charts and intraoperative records for children who had undergone resection for IMSCTs as well as dorsal column mapping and TcMEP and SSEP monitoring. Motor evoked potential data were supplemented with electromyography data obtained using a Kartush microstimulator (Medtronic Inc.). Motor strength was graded using the Medical Research Council (MRC) scale during the preoperative, immediate postoperative, and follow-up periods. Reductions in SSEPs were documented after mechanical traction, in response to maneuvers with the cavitational ultrasonic surgical aspirator (CUSA), or both. Data from 12 patients were analyzed. Three lesions were encountered in the cervical and 7 in the thoracic spinal cord. Two patients had lesions of the cervicomedullary junction and upper spinal cord. Intraoperative MEP changes were noted in half of the patients. In these cases, normal polyphasic signals converted to biphasic signals, and these changes correlated with a loss of 1-2 grades in motor strength. One patient lost MEP signals completely and recovered strength to MRC Grade 4/5. The 2 patients with high cervical lesions showed neither intraoperative MEP changes nor motor deficits postoperatively. Dorsal columns were mapped in 7 patients, and the midline was determined accurately in all 7. Somatosensory evoked potentials were decreased in 7 patients. Two patients each had 2 SSEP decreases in response to traction intraoperatively but had no new sensory findings postoperatively. Another 2 patients had 3 traction-related SSEP decreases intraoperatively, and both

  19. Onset Latency of Motor Evoked Potentials in Motor Cortical Mapping with Neuronavigated Transcranial Magnetic Stimulation.

    PubMed

    Kallioniemi, Elisa; Pitkänen, Minna; Säisänen, Laura; Julkunen, Petro

    2015-01-01

    Cortical motor mapping in pre-surgical applications can be performed using motor evoked potential (MEP) amplitudes evoked with neuronavigated transcranial magnetic stimulation. The MEP latency, which is a more stable parameter than the MEP amplitude, has not so far been utilized in motor mapping. The latency, however, may provide information about the stress in damaged motor pathways, e.g. compression by tumors, which cannot be observed from the MEP amplitudes. Thus, inclusion of this parameter could add valuable information to the presently used technique of MEP amplitude mapping. In this study, the functional cortical representations of first dorsal interosseous (FDI), abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles were mapped in both hemispheres of ten healthy righthanded volunteers. The cortical muscle representations were evaluated by the area and centre of gravity (CoG) by using MEP amplitudes and latencies. As expected, the latency and amplitude CoGs were congruent and were located in the centre of the maps but in a few subjects, instead of a single centre, several loci with short latencies were observed. In conclusion, MEP latencies may be useful in distinguishing the cortical representation areas with the most direct pathways from those pathways with prolonged latencies. However, the potential of latency mapping to identify stressed motor tract connections at the subcortical level will need to be verified in future studies with patients.

  20. Transcranial Motor-Evoked Potentials Are More Readily Acquired Than Somatosensory-Evoked Potentials in Children Younger Than 6 Years.

    PubMed

    McIntyre, Ian W; Francis, Lisa; McAuliffe, John J

    2016-01-01

    There is a general belief that somatosensory-evoked potentials (SSEPs) are more easily obtained than transcranial motor-evoked potentials (TcMEPs) in children younger than 6 years. We tested this assumption and the assumption that motor-evoked potentials are rarely obtained in children younger than 2 years. The records of all patients who were monitored during surgical procedures between April 1, 2010, and June 30, 2013, were reviewed and those who were younger than 72 months at the time of surgery were identified and analyzed for the rate of obtaining clinically useful SSEPs and motor-evoked potentials. Subgroup analysis was performed by age. A total of 146 patients were identified, 9 had SSEPs without TcMEPs monitored, 117 had both TcMEPs and SSEPs monitored, and the remainder had only electromyographic monitoring. All patients who were to have TcMEPs recorded received a total IV anesthetic. Among the 117 patients who had both SSEPs and TcMEPs monitored, clinically relevant TcMEPs were obtained more frequently than SSEPs (110/117 vs 89/117; χ = 14.82; P = 0.00012). There were significant differences between the rates of obtaining SSEPs and TcMEPs in the 0- to 23-month (P = 0.0038) and 24- to 47-month (P = 0.0056) age groups. Utilization of a double-train stimulation technique facilitated obtaining TcMEPs in the youngest patients. TcMEPs can be obtained more easily than SSEPs in patients younger than 72 months if a permissive anesthetic technique is used. The success rate for obtaining TcMEPs can be further enhanced by the use of a temporal facilitation (double-train) stimulation technique.

  1. Peripheral electrical stimulation triggered by self-paced detection of motor intention enhances motor evoked potentials.

    PubMed

    Niazi, Imran Khan; Mrachacz-Kersting, Natalie; Jiang, Ning; Dremstrup, Kim; Farina, Dario

    2012-07-01

    This paper proposes the development and experimental tests of a self-paced asynchronous brain-computer interfacing (BCI) system that detects movement related cortical potentials (MRCPs) produced during motor imagination of ankle dorsiflexion and triggers peripheral electrical stimulations timed with the occurrence of MRCPs to induce corticospinal plasticity. MRCPs were detected online from EEG signals in eight healthy subjects with a true positive rate (TPR) of 67.15 ± 7.87% and false positive rate (FPR) of 22.05 ±9.07%. The excitability of the cortical projection to the target muscle (tibialis anterior) was assessed before and after the intervention through motor evoked potentials (MEP) using transcranial magnetic stimulation (TMS). The peak of the evoked potential significantly (P=0.02) increased after the BCI intervention by 53 ± 43% (relative to preintervention measure), although the spinal excitability (tested by stretch reflexes) did not change. These results demonstrate for the first time that it is possible to alter the corticospinal projections to the tibialis anterior muscle by using an asynchronous BCI system based on online motor imagination that triggered peripheral stimulation. This type of repetitive proprioceptive feedback training based on self-generated brain signal decoding may be a requirement for purposeful skill acquisition in intact humans and in the rehabilitation of persons with brain damage.

  2. Reciprocal changes in input-output curves of motor evoked potentials while learning motor skills.

    PubMed

    Suzuki, Makoto; Kirimoto, Hikari; Onishi, Hideaki; Yamada, Sumio; Tamaki, Hiroyuki; Maruyama, Atsuo; Yamamoto, Jun-ichi

    2012-09-14

    Reciprocal inhibition of antagonist muscles is crucial for motor skill learning in humans. However, the changes in reciprocal inhibition function during the motor learning process are unknown. The aim of this study was to systematically observe the changes in reciprocal inhibition function. We investigated the optimal coil position for simultaneously eliciting motor evoked potentials (MEPs) of reciprocal muscles, and the reciprocal changes in input-output (IO) curves during motor skill training. From ten healthy volunteers, the IO curves of MEPs were measured for the midpoint between the center of gravity (CoG) of the extensor carpi radialis (ECR) and the flexor carpi radialis (FCR) muscles, for the CoG of ECR, and for the FCR muscles using transcranial magnetic stimulation (TMS). In addition, the IO curves of the ECR and the FCR muscles were measured before and after the motor skill training of rapid wrist extension. The IO curves measured at the midpoint between the CoGs of the ECR and the FCR muscles and the CoG of each muscle were homogenous. However, after training to perform rapid wrist extension, the IO curve of the agonist (ECR) muscle was increased, while the antagonist (FCR) muscle was decreased. The present findings validate the IO curves simultaneously measured for reciprocal muscles, and suggest that motor skill training could induce reciprocal change in corticospinal excitability. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Evoked Potentials in Motor Cortical Local Field Potentials Reflect Task Timing and Behavioral Performance

    PubMed Central

    Confais, Joachim; Ponce-Alvarez, Adrián; Diesmann, Markus; Riehle, Alexa

    2010-01-01

    Evoked potentials (EPs) are observed in motor cortical local field potentials (LFPs) during movement execution (movement-related potentials [MRPs]) and in response to relevant visual cues (visual evoked potentials [VEPs]). Motor cortical EPs may be directionally selective, but little is known concerning their relation to other aspects of motor behavior, such as task timing and performance. We recorded LFPs in motor cortex of two monkeys during performance of a precued arm-reaching task. A time cue at the start of each trial signaled delay duration and thereby the pace of the task and the available time for movement preparation. VEPs and MRPs were strongly modulated by the delay duration, VEPs being systematically larger in short-delay trials and MRPs larger in long-delay trials. Despite these systematic modulations related to the task timing, directional selectivity was similar in short and long trials. The behavioral reaction time was positively correlated with MRP size and negatively correlated with VEP size, within sessions. In addition, the behavioral performance improved across sessions, in parallel with a slow decrease in the size of VEPs and MRPs. Our results clearly show the strong influence of the behavioral context and performance on motor cortical population activity during movement preparation and execution. PMID:20884766

  4. Characterization of Motor and Somatosensory Evoked Potentials in the Yucatan Micropig Using Transcranial and Epidural Stimulation.

    PubMed

    Benavides, Francisco D; Santamaria, Andrea J; Bodoukhin, Nikita; Guada, Luis G; Solano, Juan P; Guest, James D

    2016-11-28

    Yucatan micropigs have brain and spinal cord dimensions similar to humans and are useful for certain spinal cord injury (SCI) translational studies. Micropigs are readily trained in behavioral tasks, allowing consistent testing of locomotor loss and recovery. However, there has been little description of their motor and sensory pathway neurophysiology. We established methods to assess motor and sensory cortical evoked potentials in the anesthetized, uninjured state. We also evaluated epidurally evoked motor and sensory stimuli from the T6 and T9 levels, spanning the intended contusion injury epicenter. Response detection frequency, mean latency and amplitude values, and variability of evoked potentials were determined. Somatosensory evoked potentials were reliable and best detected during stimulation of peripheral nerve and epidural stimulation by referencing the lateral cortex to midline Fz. The most reliable hindlimb motor evoked potential (MEP) occurred in tibialis anterior. We found MEPs in forelimb muscles in response to thoracic epidural stimulation likely generated from propriospinal pathways. Cranially stimulated MEPs were easier to evoke in the upper limbs than in the hindlimbs. Autopsy studies revealed substantial variations in cortical morphology between animals. This electrophysiological study establishes that neurophysiological measures can be reliably obtained in micropigs in a time frame compatible with other experimental procedures, such as SCI and transplantation. It underscores the need to better understand the motor control pathways, including the corticospinal tract, to determine which therapeutics are suitable for testing in the pig model.

  5. Measurement of motor evoked potentials following repetitive magnetic motor cortex stimulation during isoflurane or propofol anaesthesia.

    PubMed

    Rohde, V; Krombach, G A; Baumert, J H; Kreitschmann-Andermahr, I; Weinzierl, M; Gilsbach, J M

    2003-10-01

    Isoflurane and propofol reduce the recordability of compound muscle action potentials (CMAP) following single transcranial magnetic stimulation of the motor cortex (sTCMS). Repetition of the magnetic stimulus (repetitive transcranial magnetic stimulation, rTCMS) might allow the inhibition caused by anaesthesia with isoflurane or propofol to be overcome. We applied rTCMS (four stimuli; inter-stimulus intervals of 3, 4, 5 ms (333, 250, 200 Hz), output 2.5 Tesla) in 27 patients and recorded CMAP from the hypothenar and anterior tibial muscle. Anaesthesia was maintained with fentanyl 0.5-1 microg kg(-1) x h(-1) and either isoflurane 1.2% (10 patients) or propofol 5 mg kg(-1) x h(-1) with nitrous oxide 60% in oxygen (17 patients). No CMAP were detected during isoflurane anaesthesia. During propofol anaesthesia 333 Hz, four-pulse magnetic stimulation evoked CMAP in the hypothenar muscle in 75%, and in the anterior tibial muscle in 65% of the patients. Less response was obtained with 250 and 200 Hz stimulation. In most patients, rTCMS can overcome suppression of CMAP during propofol/nitrous oxide anaesthesia, but not during isoflurane anaesthesia. A train of four magnetic stimuli at a frequency of 333 Hz is most effective in evoking potentials from the upper and lower limb muscles. The authors conclude that rTCMS can be used for evaluation of the descending motor pathways during anaesthesia.

  6. Diagnostic Accuracy of Combined Multimodality Somatosensory Evoked Potential and Transcranial Motor Evoked Potential Intraoperative Monitoring in Patients With Idiopathic Scoliosis.

    PubMed

    Thirumala, Parthasarathy D; Huang, Jessie; Thiagarajan, Karthy; Cheng, Hannah; Balzer, Jeffrey; Crammond, Donald J

    2016-10-01

    Systematic review. The aim of the study was to determine the predictive value of combined multimodality somatosensory evoked potential (SSEP) and transcranial motor evoked potential (TcMEP) monitoring in detecting impending neurological injury during surgery for idiopathic scoliosis. The diagnostic of motor evoked potential monitoring and SSEP monitoring have been established. However, the predictive value of combined multimodality SSEP and TcMEP monitoring in detecting impending neurological injury during surgery for idiopathic scoliosis has not been evaluated. A systematic literature search was performed using PubMed/MEDLINE, Web of Science, and EMBASE from 1974 to January 2015. All titles and abstracts were independently reviewed by the authors. We included all studies that were (1) randomized controlled trials, prospective or retrospective cohort studies; (2) included patients with idiopathic scoliosis undergoing scoliosis correction surgery; (3) included multimodality SSEP and TcMEP monitoring during spinal surgery; (4) included immediate postoperative neurological assessment; (5) idiopathic scoliosis patient population n ≥25; and (6) published in English. Seven studies comprising a total of 2052 patients with idiopathic scoliosis were included in our meta-analysis. The incidence of neurological deficit in this cohort was 0.93%. The pooled sensitivity, specificity, and Diagnostic Odds Ratio were 82.6% (95% CI 56.7%-94.5%), 94.4% (95% CI 85.1%-98.0%), and 106.16 (95% CI 24.952-451.667), respectively. The area under the curve was 0.928, indicating excellent discriminatory ability. Idiopathic scoliosis corrective surgery patients who experience a new neurological deficit are 106.16 times more likely to have had an SSEP and/or TcMEP change during corrective procedures. The results of this meta-analysis demonstrate that combined multimodality SSEP and TcMEP monitoring possess some advantage over use of each alone, and that intraoperative neurophysiological

  7. What Do TMS-Evoked Motor Potentials Tell Us About Motor Learning?

    PubMed

    Carson, Richard G; Ruddy, Kathy L; McNickle, Emmet

    2016-01-01

    Thirty years ago, the first magnetic device capable of stimulating the human brain without discomfort through the intact skull was unveiled in Sheffield, England (Barker et al. in Lancet 1:1106-1107, 1985). Since that time, transcranial magnetic stimulation (TMS) has become the tool of choice for many scientists investigating human motor control and learning. In light of the fact that there are limits to the information that can be provided by any experimental technique, we first make the case that the necessarily restricted explanatory scope of the TMS technique-and the motor-evoked potentials to which it gives rise, is not yet reflected adequately in the research literature. We also argue that this inattention, coupled with the pervasive adoption of TMS as an investigative tool, may be restricting the elaboration of knowledge concerning the neural processes that mediate human motor learning. In order to make these points, we use as an exemplar the study of cross-education-the interlimb transfer of functional capacity.

  8. Prediction of Motor Recovery Using Quantitative Parameters of Motor Evoked Potential in Patients With Stroke

    PubMed Central

    2016-01-01

    Objective To investigate the clinical significance of quantitative parameters in transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEP) which can be adopted to predict functional recovery of the upper limb in stroke patients in the early subacute phase. Methods One hundred thirteen patients (61 men, 52 women; mean age 57.8±12.2 years) who suffered faiarst-ever stroke were included in this study. All participants underwent TMS-induced MEP session to assess the corticospinal excitability of both hand motor cortices within 3 weeks after stroke onset. After the resting motor threshold (rMT) was assessed, five sweeps of MEP were performed, and the mean amplitude of the MEP was measured. Latency of MEP, volume of the MEP output curve, recruitment ratios, and intracortical inhibition and facilitation were also measured. Motor function was assessed using the Fugl-Meyer Assessment scale (FMA) within 3 weeks and at 3 months after stroke onset. Correlation analysis was performed between TMS-induced MEP derived measures and FMA scores. Results In the MEP response group, rMT and rMT ratio measures within 3 weeks after stroke onset showed a significant negative correlation with the total and upper limb FMA scores at 3 months after stroke (p<0.001). Multiple regression analysis revealed that FMA score and rMT ratio, but not rMT within 3 weeks were independent prognostic factors for FMA scores at 3 months after stroke. Conclusion These results indicated that the quantitative parameter of TMS-induced MEP, especially rMT ratio in the early subacute phase, could be used as a parameter to predict motor function in patients with stroke. PMID:27847710

  9. Role of motor evoked potentials in diagnosis of cauda equina and lumbosacral cord lesions.

    PubMed

    Di Lazzaro, V; Pilato, F; Oliviero, A; Saturno, E; Dileone, M; Tonali, P A

    2004-12-28

    To determine the diagnostic value of motor evoked potentials (MEPs) in the diagnosis of lumbosacral cord disorders. MEPs in 37 patients with sensory and motor deficits in the lower limbs were studied. MRI demonstrated spinal cord involvement in 10 patients and cauda equina lesions in 27 patients. A double determination of central motor conduction time (CMCT), calculated as the difference between the latencies of responses evoked by cortical and paravertebral magnetic stimulation and as the difference between the latency of cortical MEP and the total peripheral conduction time calculated from the F-wave latency, enabled discrimination between a delay along the proximal root and a delay along the corticospinal tract. An abnormality of the CMCT calculated with both techniques is indicative of central motor pathway damage, whereas an abnormality of the CMCT calculated from the latency of responses evoked by paravertebral magnetic stimulation associated with a normal CMCT calculated from the F-wave latency suggests a cauda equina lesion. Neurophysiologic findings strongly correlated with the lesion site documented by MRI (cauda equina or lumbosacral cord). All patients with MR evidence of cord involvement had an abnormality of CMCT calculated with both methods, suggesting a lesion of central motor pathways. Clinical examination often failed to document a spinal cord lesion, suggesting pure peripheral involvement in 5 of the 10 patients with MR evidence of cord lesion. Motor evoked potential recording is an accurate and easily applicable test for the diagnosis of lumbosacral spinal cord lesions.

  10. Different Effects of Implicit and Explicit Motor Sequence Learning on Latency of Motor Evoked Potential Evoked by Transcranial Magnetic Stimulation on the Primary Motor Cortex

    PubMed Central

    Hirano, Masato; Kubota, Shinji; Koizume, Yoshiki; Tanaka, Shinya; Funase, Kozo

    2017-01-01

    Motor training induces plastic changes in the primary motor cortex (M1). However, it is unclear whether and how the latency of motor-evoked potentials (MEP) and MEP amplitude are affected by implicit and/or explicit motor learning. Here, we investigated the changes in M1 excitability and MEP latency induced by implicit and explicit motor learning. The subjects performed a serial reaction time task (SRTT) with their five fingers. In this task, visual cues were lit up sequentially along with a predetermined order. Through training, the subjects learned the order of sequence implicitly and explicitly. Before and after the SRTT, we recorded MEP at 25 stimulation points around the hot spot for the flexor pollicis brevis (FPB) muscle. Although no changes in MEP amplitude were observed in either session, we found increases in MEP latency and changes in histogram of MEP latency after implicit learning. Our results suggest that reorganization across the motor cortices occurs during the acquisition of implicit knowledge. In contrast, acquisition of explicit knowledge does not appear to induce the reorganization based on the measures we recorded. The fact that the above mentioned increases in MEP latency occurred without any alterations in MEP amplitude suggests that learning has different effects on different physiological signals. In conclusion, our results propose that analyzing a combination of some indices of M1 excitability, such as MEP amplitude and MEP latency, is encouraged in order to understand plasticity across motor cortices. PMID:28101014

  11. Different Effects of Implicit and Explicit Motor Sequence Learning on Latency of Motor Evoked Potential Evoked by Transcranial Magnetic Stimulation on the Primary Motor Cortex.

    PubMed

    Hirano, Masato; Kubota, Shinji; Koizume, Yoshiki; Tanaka, Shinya; Funase, Kozo

    2016-01-01

    Motor training induces plastic changes in the primary motor cortex (M1). However, it is unclear whether and how the latency of motor-evoked potentials (MEP) and MEP amplitude are affected by implicit and/or explicit motor learning. Here, we investigated the changes in M1 excitability and MEP latency induced by implicit and explicit motor learning. The subjects performed a serial reaction time task (SRTT) with their five fingers. In this task, visual cues were lit up sequentially along with a predetermined order. Through training, the subjects learned the order of sequence implicitly and explicitly. Before and after the SRTT, we recorded MEP at 25 stimulation points around the hot spot for the flexor pollicis brevis (FPB) muscle. Although no changes in MEP amplitude were observed in either session, we found increases in MEP latency and changes in histogram of MEP latency after implicit learning. Our results suggest that reorganization across the motor cortices occurs during the acquisition of implicit knowledge. In contrast, acquisition of explicit knowledge does not appear to induce the reorganization based on the measures we recorded. The fact that the above mentioned increases in MEP latency occurred without any alterations in MEP amplitude suggests that learning has different effects on different physiological signals. In conclusion, our results propose that analyzing a combination of some indices of M1 excitability, such as MEP amplitude and MEP latency, is encouraged in order to understand plasticity across motor cortices.

  12. Motor potentials evoked by navigated transcranial magnetic stimulation in healthy subjects.

    PubMed

    Säisänen, Laura; Julkunen, Petro; Niskanen, Eini; Danner, Nils; Hukkanen, Taina; Lohioja, Tarja; Nurkkala, Jouko; Mervaala, Esa; Karhu, Jari; Könönen, Mervi

    2008-12-01

    Navigated transcranial magnetic stimulation (TMS) is a tool for targeted, noninvasive stimulation of cerebral cortex. Transcranial stimuli can depolarize neurons and evoke measurable effects which are unique in two ways: the effects are caused directly and without a consciousness of the subject, and, the responses from peripheral muscles provide a direct measure for the integrity of the whole motor pathway. The clinical relevance of the method has not always been fully exposed because localizing the optimal stimulation site and determining the optimal stimulation strength have been dependent on time-consuming experimentation and skill. Moreover, in many disorders it has been uncertain, whether the lack of motor responses is the result of true pathophysiological changes or merely because of unoptimal stimulation. We characterized the muscle responses from human primary motor cortex system by navigated TMS to provide normative values for the clinically relevant TMS parameters on 65 healthy volunteers aged 22 to 81 years. We delivered focal TMS pulses on the primary motor area (M1) and recorded muscle responses on thenar and anterior tibial muscles. Motor threshold, latencies and amplitudes of motor-evoked potentials, and silent period duration were measured. The correction of the motor-evoked potential latency for subjects' height is provided. In conclusion, we provide a modified baseline of TMS-related parameters for healthy subjects. Earlier such large-scale baseline material has not been available.

  13. Reduced evoked motor and sensory potential amplitudes in obstructive sleep apnea patients.

    PubMed

    Mihalj, Mario; Lušić, Linda; Đogaš, Zoran

    2016-06-01

    It is unknown to what extent chronic intermittent hypoxaemia in obstructive sleep apnea causes damage to the motor and sensory peripheral nerves. It was hypothesized that patients with obstructive sleep apnea would have bilaterally significantly impaired amplitudes of both motor and sensory peripheral nerve-evoked potentials of both lower and upper limbs. An observational study was conducted on 43 patients with obstructive sleep apnea confirmed by the whole-night polysomnography, and 40 controls to assess the relationship between obstructive sleep apnea and peripheral neuropathy. All obstructive sleep apnea subjects underwent standardized electroneurographic testing, with full assessment of amplitudes of evoked compound muscle action potentials, sensory neural action potentials, motor and sensory nerve conduction velocities, and distal motor and sensory latencies of the median, ulnar, peroneal and sural nerves, bilaterally. All nerve measurements were compared with reference values, as well as between the untreated patients with obstructive sleep apnea and control subjects. Averaged compound muscle action potential and sensory nerve action potential amplitudes were significantly reduced in the nerves of both upper and lower limbs in patients with obstructive sleep apnea compared with controls (P < 0.001). These results confirmed that patients with obstructive sleep apnea had significantly lower amplitudes of evoked action potentials of both motor and sensory peripheral nerves. Clinical/subclinical axonal damage exists in patients with obstructive sleep apnea to a greater extent than previously thought.

  14. Motor Evoked Potentials in 43 High Risk Spine Deformities

    PubMed Central

    Biscevic, Mirza; Biscevic, Sejla; Ljuca, Farid; Smrke, Barbara UR; Ozturk, Cagatay; Tiric-Campara, Merita

    2014-01-01

    ABSTRACT Introduction: Correction of pediatric spine deformities is challenging surgical procedures. This fragile group of patients has many risk factors, therefore prevention of most fearing complication-paraplegia is extremely important. Monitoring of transmission of neurophysiological impulses through motor and sensor pathways of spinal cord gives us an insight into cord's function, and predicts postoperative neurological status. Goal: Aim of this work is to present our experiences in monitoring of spinal cord motor function - MEP during surgical corrections of the hardest pediatric spine deformities, pointing on the most dangerous aspects. Material and methods: We analyzed incidence of MEP changes and postoperative neurological status in patients who had major spine correcting surgery in period April ‘11- April ‘14 on our Spine department. Results: Two of 43 patients or 4.6% in our group experienced significant MEP changes during their major spine reconstructive surgeries. We promptly reduced distractive forces, and MEP normalized, and there were no neurological deficit. Neuromonitoring is reliable method which allows us to “catch” early signs of neurological deficits, when they are still in reversible phase. Although IONM cannot provide complete protection of neurological deficit (it reduces risk of paraplegia about 75%), it at least afford a comfort to the surgeon being fear free that his patient is neurologically intact during long lasting procedures. PMID:25568569

  15. Impaired lumbar movement perception in association with postural stability and motor- and somatosensory-evoked potentials in lumbar spinal stenosis.

    PubMed

    Leinonen, Ville; Määttä, Sara; Taimela, Simo; Herno, Arto; Kankaanpää, Markku; Partanen, Juhani; Kansanen, Martti; Hänninen, Osmo; Airaksinen, Olavi

    2002-05-01

    A descriptive study of the associations between different neurophysiologic findings in patients with lumbar spinal stenosis. To evaluate the ability to sense a change in lumbar position and the associations between lumbar movement perception, postural stability, and motor-evoked potentials and somatosensory-evoked potentials. Patients with low back pain have impaired postural control and impaired lumbar proprioception. Altered motor-evoked potentials and somatosensory-evoked potentials have been often observed in lumbar spinal stenosis. The study included 26 patients with clinically and radiologically diagnosed lumbar spinal stenosis. Their ability to sense lumbar rotation was assessed in a previously validated motorized trunk rotation unit in the seated position. The abilities to indicate the movement direction and the movement magnitude were used as indexes of the ability to sense the lumbar rotatory movement. The postural stability was measured with a vertical force platform. The motor-evoked potentials were elicited by transcranial and lumbar stimulation and recorded from anterior tibialis muscles. The somatosensory-evoked potentials were elicited by transcutaneous electrical stimulation of the tibial nerve at the ankle. Twenty patients (76.9%; P = 0.006) reported the wrong movement direction. Furthermore, the patients consistently localized the movement sensation in their shoulders instead of the lumbar region. The altered motor-evoked potentials and somatosensory-evoked potentials were observed in 11 and 16 patients, respectively. Abnormal motor-evoked potentials had inconsistent associations with impaired movement perception and postural stability and abnormal somatosensory-evoked potentials had no associations with other findings. Many patients with lumbar spinal stenosis have difficulties in sensing the lumbar rotational movement, which may indicate impaired proprioceptive abilities. Abnormal motor-evoked potentials and somatosensory-evoked potentials are

  16. Increased threshold of short-latency motor evoked potentials in transgenic mice expressing Channelrhodopsin-2.

    PubMed

    Wu, Wei; Xiong, Wenhui; Zhang, Ping; Chen, Lifang; Fang, Jianqiao; Shields, Christopher; Xu, Xiao-Ming; Jin, Xiaoming

    2017-01-01

    Transgenic mice that express channelrhodopsin-2 or its variants provide a powerful tool for optogenetic study of the nervous system. Previous studies have established that introducing such exogenous genes usually does not alter anatomical, electrophysiological, and behavioral properties of neurons in these mice. However, in a line of Thy1-ChR2-YFP transgenic mice (line 9, Jackson lab), we found that short-latency motor evoked potentials (MEPs) induced by transcranial magnetic stimulation had a longer latency and much lower amplitude than that of wild type mice. MEPs evoked by transcranial electrical stimulation also had a much higher threshold in ChR2 mice, although similar amplitudes could be evoked in both wild and ChR2 mice at maximal stimulation. In contrast, long-latency MEPs evoked by electrically stimulating the motor cortex were similar in amplitude and latency between wild type and ChR2 mice. Whole-cell patch clamp recordings from layer V pyramidal neurons of the motor cortex in ChR2 mice revealed no significant differences in intrinsic membrane properties and action potential firing in response to current injection. These data suggest that corticospinal tract is not accountable for the observed abnormality. Motor behavioral assessments including BMS score, rotarod, and grid-walking test showed no significant differences between the two groups. Because short-latency MEPs are known to involve brainstem reticulospinal tract, while long-latency MEPs mainly involve primary motor cortex and dorsal corticospinal tract, we conclude that this line of ChR2 transgenic mice has normal function of motor cortex and dorsal corticospinal tract, but reduced excitability and responsiveness of reticulospinal tracts. This abnormality needs to be taken into account when using these mice for related optogenetic study.

  17. Monitoring of Motor and Somatosensory Evoked Potentials During Spine Surgery: Intraoperative Changes and Postoperative Outcomes

    PubMed Central

    2016-01-01

    Objective To evaluate whether the combination of muscle motor evoked potentials (mMEPs) and somatosensory evoked potentials (SEPs) measured during spinal surgery can predict immediate and permanent postoperative motor deficits. Methods mMEP and SEP was monitored in patients undergoing spinal surgery between November 2012 and July 2014. mMEPs were elicited by a train of transcranial electrical stimulation over the motor cortex and recorded from the upper/lower limbs. SEPs were recorded by stimulating the tibial and median nerves. Results Combined mMEP/SEP recording was successfully achieved in 190 operations. In 117 of these, mMEPs and SEPs were stable and 73 showed significant changes. In 20 cases, motor deficits in the first 48 postoperative hours were observed and 6 patients manifested permanent neurological deficits. The two potentials were monitored in a number of spinal surgeries. For surgery on spinal deformities, the sensitivity and specificity of combined mMEP/SEP monitoring were 100% and 92.4%, respectively. In the case of spinal cord tumor surgeries, sensitivity was only 50% but SEP changes were observed preceding permanent motor deficits in some cases. Conclusion Intraoperative monitoring is a useful tool in spinal surgery. For spinal deformity surgery, combined mMEP/SEP monitoring showed high sensitivity and specificity; in spinal tumor surgery, only SEP changes predicted permanent motor deficits. Therefore, mMEP, SEP, and joint monitoring may all be appropriate and beneficial for the intraoperative monitoring of spinal surgery. PMID:27446784

  18. Basic Principles and Recent Trends of Transcranial Motor Evoked Potentials in Intraoperative Neurophysiologic Monitoring.

    PubMed

    Tsutsui, Shunji; Yamada, Hiroshi

    2016-08-15

    Transcranial motor evoked potentials (TcMEPs), which are muscle action potentials elicited by transcranial brain stimulation, have been the most popular method for the last decade to monitor the functional integrity of the motor system during surgery. It was originally difficult to record reliable and reproducible potentials under general anesthesia, especially when inhalation-based anesthetic agents that suppressed the firing of anterior horn neurons were used. Advances in anesthesia, including the introduction of intravenous anesthetic agents, and progress in stimulation techniques, including the use of pulse trains, improved the reliability and reproducibility of TcMEP responses. However, TcMEPs are much smaller in amplitude compared with compound muscle action potentials evoked by maximal peripheral nerve stimulation, and vary from one trial to another in clinical practice, suggesting that only a limited number of spinal motor neurons innervating the target muscle are excited in anesthetized patients. Therefore, reliable interpretation of the critical changes in TcMEPs remains difficult and controversial. Additionally, false negative cases have been occasionally encountered. Recently, several facilitative techniques using central or peripheral stimuli, preceding transcranial electrical stimulation, have been employed to achieve sufficient depolarization of motor neurons and augment TcMEP responses. These techniques might have potentials to improve the reliability of intraoperative motor pathway monitoring using TcMEPs.

  19. Basic Principles and Recent Trends of Transcranial Motor Evoked Potentials in Intraoperative Neurophysiologic Monitoring

    PubMed Central

    TSUTSUI, Shunji; YAMADA, Hiroshi

    2016-01-01

    Transcranial motor evoked potentials (TcMEPs), which are muscle action potentials elicited by transcranial brain stimulation, have been the most popular method for the last decade to monitor the functional integrity of the motor system during surgery. It was originally difficult to record reliable and reproducible potentials under general anesthesia, especially when inhalation-based anesthetic agents that suppressed the firing of anterior horn neurons were used. Advances in anesthesia, including the introduction of intravenous anesthetic agents, and progress in stimulation techniques, including the use of pulse trains, improved the reliability and reproducibility of TcMEP responses. However, TcMEPs are much smaller in amplitude compared with compound muscle action potentials evoked by maximal peripheral nerve stimulation, and vary from one trial to another in clinical practice, suggesting that only a limited number of spinal motor neurons innervating the target muscle are excited in anesthetized patients. Therefore, reliable interpretation of the critical changes in TcMEPs remains difficult and controversial. Additionally, false negative cases have been occasionally encountered. Recently, several facilitative techniques using central or peripheral stimuli, preceding transcranial electrical stimulation, have been employed to achieve sufficient depolarization of motor neurons and augment TcMEP responses. These techniques might have potentials to improve the reliability of intraoperative motor pathway monitoring using TcMEPs. PMID:26935781

  20. Poor diagnostic accuracy of transcranial motor and somatosensory evoked potential monitoring during brainstem cavernoma resection.

    PubMed

    Shiban, Ehab; Zerr, Marina; Huber, Thomas; Boeck-Behrends, Tobias; Wostrack, Maria; Ringel, Florian; Meyer, Bernhard; Lehmberg, Jens

    2015-11-01

    Microsurgical resection of brainstem cavernomas carries a high risk of new postoperative morbidity such as cranial nerve, motor and sensory deficits as well as functional deterioration. Intraoperative monitoring is used to avoid impending damage to these highly eloquent tracts. However, data on neurophysiological monitoring during resection of brainstem cavernomas are lacking. Consecutive patients with brainstem cavernomas who underwent surgical removal from June 2007 to December 2014 were retrospectively analysed. Transcranial motor-evoked potential (MEP) and somatosensory-evoked potential (SSEP) monitorings were performed in all cases. The evoked potential (EP) monitoring data were reviewed and related to new postoperative motor and sensory deficits and postoperative imaging. Clinical outcomes were assessed during follow-up. Twenty-six consecutive patients with brainstem cavernoma underwent 27 surgical resections within this study. MEP and SSEP monitoring was technically feasible in 26 and 27 cases, respectively. MEP sensitivity and specificity were 33 and 88 %, respectively. MEP positive and negative predictive values were 28 and 78 %, respectively. SSEP sensitivity and specificity were 20 and 81 %, respectively. SSEP positive and negative predictive values were 20 and 81 %, respectively. In continuous MEP and SSEP monitoring during brainstem cavernoma microsurgery, high rates of false-positive and -negative results are encountered, resulting in low positive and relatively high negative predictive values. Careful interpretation of the intraoperative monitoring results is essential in order to avoid potentially unjustified termination of brainstem cavernoma resection.

  1. Loss of lower limb motor evoked potentials and spinal cord injury during the initial exposure in scoliosis surgery.

    PubMed

    Legatt, Alan D; Fried, Stephen J; Amaral, Terry D; Sarwahi, Vishal; Moguilevitch, Marina

    2014-04-01

    To report a case of motor evoked potential changes and spinal cord injury during the initial dissection in scoliosis surgery. Motor evoked potentials to transcranial electrical stimulation were recorded from multiple muscles. Somatosensory evoked potentials to limb nerve stimulation were recorded from the scalp. Clear motor evoked potentials were initially present in all monitored muscles. The patient was then pharmacologically paralyzed for the initial dissection. More than usual bleeding was encountered during that dissection, prompting transfusion. As the neuromuscular blockade subsided, motor evoked potentials persisted in the hand muscles but disappeared and remained absent in all monitored leg muscles. The spine had not been instrumented. A wake-up test demonstrated paraplegia; the surgery was aborted. There were no adverse somatosensory evoked potential changes. MRI showed an anterior spinal cord infarct. Copious soft tissue bleeding during the initial dissection might have lowered pressures in critical segmental arteries enough to cause spinal cord infarction through a steal phenomenon. The lack of somatosensory evoked potential changes reflected sparing of the dorsal columns. When neuromuscular blockade is used during the initial soft tissue dissection, motor evoked potentials should be assessed after this, but before spinal instrumentation, to determine whether there had been any spinal cord compromise during the initial dissection.

  2. Direct cortical stimulation but not transcranial electrical stimulation motor evoked potentials detect brain ischemia during brain tumor resection.

    PubMed

    Li, Fenghua; Deshaies, Eric M; Allott, Geoffrey; Canute, Gregory; Gorji, Reza

    2011-09-01

    Motor evoked potentials (MEPs) elicited by both direct cortical stimulation (DCS) and transcranial electrical stimulation are used during brain tumor resection. Parallel use of direct cortical stimulation motor evoked potentials (DCS-MEPs) and transcranial electrical stimulation motor evoked potentials (TCeMEPs) has been practiced during brain tumor resection. We report that DCS-MEPs elicited by direct subdural grid stimulation, but not TCeMEPs, detected brain ischemia during brain tumor resection. Following resection of a brainstem high-grade glioma in a 21-year-old, the threshold of cortical motor-evoked-potentials (cMEPs) increased from 13 mA to 20 mA while amplitudes decreased. No changes were noted in transcranial motor evoked potentials (TCMEPs), somatosensory evoked potentials (SSEPs), auditory evoked potentials (AEPs), anesthetics, or hemodynamic parameters. Our case showed the loss of cMEPs and SSEPs, but not TCeMEPs. Permanent loss of DCS-MEPs and SSEPs was correlated with permanent left hemiplegia in our patient even when appropriate action was taken. Parallel use of DCS- and TCeMEPs with SSEPs improves sensitivity of intraoperative detection of motor impairment. DCS may be superior to TCeMEPs during brain tumor resection.

  3. Parkinson's disease rigidity: magnetic motor evoked potentials in a small hand muscle.

    PubMed

    Cantello, R; Gianelli, M; Bettucci, D; Civardi, C; De Angelis, M S; Mutani, R

    1991-09-01

    We studied the EMG potentials evoked in the bilateral first dorsal interosseus muscle by electromagnetic stimulation of the corticomotoneuronal descending system in 10 Parkinson's disease patients and in 10 age- and sex-matched normal controls. We selected patients who did not have tremor but had predominant rigidity with asymmetric body involvement. On the rigid side of the PD patients, the threshold to cortical stimulation was lower than on the contralateral side or than normal values. On average, patients had normal central conduction times, but their motor evoked potentials (MEPs) on the rigid side were larger than those of controls when the cortical stimulus was at rest or during slight tonic contraction of the target muscle. In the latter condition, a silent period shorter than that of controls followed MEPs, whereas the peripheral silent period following ulnar nerve stimulation at the wrist was prolonged. Alpha motor neuron excitability, tested by the F-wave method, was enhanced on the rigid side at rest. In rigidity, spinal motor nuclei may be more responsive than normal to descending inputs from motor cortex, or the entire corticomotoneuron system may prove hyperexcitable under given conditions.

  4. Effect of neck flexion on somatosensory and motor evoked potentials in Hirayama disease.

    PubMed

    Abraham, A; Gotkine, M; Drory, V E; Blumen, S C

    2013-11-15

    Hirayama disease (HD) is a rare motor disorder mainly affecting young men, characterized by atrophy and weakness of forearm and hand muscles corresponding to a C7-T1 myotome distribution. The weakness is usually unilateral or asymmetric and progression usually stops within several years. The etiology of HD is not well understood. One hypothesis, mainly based on MRI findings, is that the weakness is a consequence of cervical flexion myelopathy. The aim of this study was to explore the function of corticospinal and ascending somatosensory pathways during neck flexion using evoked responses. 15 men with HD and 7 age-matched control male subjects underwent somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP) studies with the neck in neutral position and fully flexed. SSEP studies included electrical stimulation of median and ulnar nerves at the wrist, and tibial nerve at the ankle with recording over the ipsilateral Erb's point, cervical spine, and contralateral sensory cortex. MEP recordings were obtained by magnetic stimulation of the motor cortex and the cervical lower spinal roots; the evoked responses were recorded from the contralateral thenar and abductor hallucis muscles. MEP recordings demonstrated significant lower amplitudes, and slightly prolonged latencies in HD patients on cervical stimulation, compared to control subjects. During neck flexion, MEP studies also demonstrated a statistically significant drop in mean upper limb amplitude on cervical stimulation in HD patients, as well as in control subjects, although to a lesser degree. In contrast, no significant differences were found in SSEP studies in HD patients compared to control subjects, or between neutral and flexed position in these groups. The study shows a negative effect of cervical flexion on MEP amplitudes in HD patients as well as in control subjects, requiring more studies to investigate its significance. Neck flexion did not have an influence on any SSEP parameters in

  5. Auditory- and Vestibular-Evoked Potentials Correlate with Motor and Non-Motor Features of Parkinson's Disease.

    PubMed

    Shalash, Ali Soliman; Hassan, Dalia Mohamed; Elrassas, Hanan Hani; Salama, Mohamed Mosaad; Méndez-Hernández, Edna; Salas-Pacheco, José M; Arias-Carrión, Oscar

    2017-01-01

    Degeneration of several brainstem nuclei has been long related to motor and non-motor symptoms (NMSs) of Parkinson's disease (PD). Nevertheless, due to technical issues, there are only a few studies that correlate that association. Brainstem auditory-evoked potential (BAEP) and vestibular-evoked myogenic potential (VEMP) responses represent a valuable tool for brainstem assessment. Here, we investigated the abnormalities of BAEPs, ocular VEMPs (oVEMPs), and cervical VEMPs (cVEMPs) in patients with PD and its correlation to the motor and NMSs. Fifteen patients diagnosed as idiopathic PD were evaluated by Unified Parkinson's Disease Rating Scale and its subscores, Hoehn and Yahr scale, Schwab and England scale, and Non-Motor Symptoms Scale. PD patients underwent pure-tone, speech audiometry, tympanometry, BAEP, oVEMPs, and cVEMPs, and compared to 15 age-matched control subjects. PD subjects showed abnormal BAEP wave morphology, prolonged absolute latencies of wave V and I-V interpeak latencies. Absent responses were the marked abnormality seen in oVEMP. Prolonged latencies with reduced amplitudes were seen in cVEMP responses. Rigidity and bradykinesia were correlated to the BAEP and cVEMP responses contralateral to the clinically more affected side. Contralateral and ipsilateral cVEMPs were significantly correlated to sleep (p = 0.03 and 0.001), perception (p = 0.03), memory/cognition (p = 0.025), and urinary scores (p = 0.03). The oVEMP responses showed significant correlations to cardiovascular (p = 0.01) and sexual dysfunctions (p = 0.013). PD is associated with BAEP and VEMP abnormalities that are correlated to the motor and some non-motor clinical characteristics. These abnormalities could be considered as potential electrophysiological biomarkers for brainstem dysfunction and its associated motor and non-motor features.

  6. Auditory- and Vestibular-Evoked Potentials Correlate with Motor and Non-Motor Features of Parkinson’s Disease

    PubMed Central

    Shalash, Ali Soliman; Hassan, Dalia Mohamed; Elrassas, Hanan Hani; Salama, Mohamed Mosaad; Méndez-Hernández, Edna; Salas-Pacheco, José M.; Arias-Carrión, Oscar

    2017-01-01

    Degeneration of several brainstem nuclei has been long related to motor and non-motor symptoms (NMSs) of Parkinson’s disease (PD). Nevertheless, due to technical issues, there are only a few studies that correlate that association. Brainstem auditory-evoked potential (BAEP) and vestibular-evoked myogenic potential (VEMP) responses represent a valuable tool for brainstem assessment. Here, we investigated the abnormalities of BAEPs, ocular VEMPs (oVEMPs), and cervical VEMPs (cVEMPs) in patients with PD and its correlation to the motor and NMSs. Fifteen patients diagnosed as idiopathic PD were evaluated by Unified Parkinson’s Disease Rating Scale and its subscores, Hoehn and Yahr scale, Schwab and England scale, and Non-Motor Symptoms Scale. PD patients underwent pure-tone, speech audiometry, tympanometry, BAEP, oVEMPs, and cVEMPs, and compared to 15 age-matched control subjects. PD subjects showed abnormal BAEP wave morphology, prolonged absolute latencies of wave V and I–V interpeak latencies. Absent responses were the marked abnormality seen in oVEMP. Prolonged latencies with reduced amplitudes were seen in cVEMP responses. Rigidity and bradykinesia were correlated to the BAEP and cVEMP responses contralateral to the clinically more affected side. Contralateral and ipsilateral cVEMPs were significantly correlated to sleep (p = 0.03 and 0.001), perception (p = 0.03), memory/cognition (p = 0.025), and urinary scores (p = 0.03). The oVEMP responses showed significant correlations to cardiovascular (p = 0.01) and sexual dysfunctions (p = 0.013). PD is associated with BAEP and VEMP abnormalities that are correlated to the motor and some non-motor clinical characteristics. These abnormalities could be considered as potential electrophysiological biomarkers for brainstem dysfunction and its associated motor and non-motor features. PMID:28289399

  7. Immediate plasticity in the motor pathways after spinal cord hemisection: implications for transcranial magnetic motor-evoked potentials.

    PubMed

    Fujiki, Minoru; Kobayashi, Hidenori; Inoue, Ryo; Ishii, Keisuke

    2004-06-01

    The present study evaluates motor functional recovery after C2 spinal cord hemisection with or without contralateral brachial root transection, which causes a condition that is similar to the crossed phrenic phenomenon on rats. Descending motor pathways, including the reticulospinal extrapyramidal tract and corticospinal pyramidal tracts, were evaluated by transcranial magnetic motor-evoked potentials (mMEPs) and direct cortical electrical motor-evoked potentials (eMEP), respectively. All MEPs recorded from the left forelimb were abolished immediately after the left C2 hemisection. Left mMEPs recovered dramatically immediately after contralateral right brachial root transection. Corticospinal eMEPs never recovered, regardless of transection. The facilitation of mMEPs in animals that had undergone combined contralateral root transection was well correlated with open-field behavioral motor performance. Both electrophysiological and neurological facilitations were significantly attenuated by the selective serotonin synthesis inhibitor para-chlorophenylalanine (p-CPA). These results suggest that serotonergic reticulospinal fibers located contralateral to hemisection contribute to the behavioral and electrophysiological improvement that immediately follows spinal cord injury (SCI).

  8. Quantification of the proportion of motor neurons recruited by transcranial electrical stimulation during intraoperative motor evoked potential monitoring.

    PubMed

    Tsutsui, Shunji; Yamada, Hiroshi; Hashizume, Hiroshi; Minamide, Akihito; Nakagawa, Yukihiro; Iwasaki, Hiroshi; Yoshida, Munehito

    2013-12-01

    Transcranial motor evoked potentials (TcMEPs) are widely used to monitor motor function during spinal surgery. However, they are much smaller and more variable in amplitude than responses evoked by maximal peripheral nerve stimulation, suggesting that a limited number of spinal motor neurons to the target muscle are excited by transcranial stimulation. The aim of this study was to quantify the proportion of motor neurons recruited during TcMEP monitoring under general anesthesia. In twenty patients who underwent thoracic and/or lumbar spinal surgery with TcMEP monitoring, the triple stimulation technique (TST) was applied to the unilateral upper arm intraoperatively. Total intravenous anesthesia was employed. Trains of four stimuli were delivered with maximal intensity and an inter-pulse interval of 1.5 ms. TST responses were recorded from the abductor digiti minimi muscle, and the negative peak amplitude and area were measured and compared between the TST test (two collisions between transcranial and proximal and distal peripheral stimulation) and control response (two collisions between two proximal and one distal peripheral stimulation). The highest degree of superimposition of the TST test and control responses was chosen from several trials per patient. The average ratios (test:control) were 17.1 % (range 1.8-38 %) for the amplitudes and 21.6 % (range 2.9-40 %) for the areas. The activity of approximately 80 % of the motor units to the target muscle cannot be detected by TcMEP monitoring. Therefore, changes in evoked potentials must be interpreted cautiously when assessing segmental motor function with TcMEP monitoring.

  9. Motor evoked potentials in the preoperative and postoperative assessment of normal pressure hydrocephalus.

    PubMed Central

    Zaaroor, M; Bleich, N; Chistyakov, A; Pratt, H; Feinsod, M

    1997-01-01

    Motor evoked potentials and central motor conduction time (CMCT) were examined from both upper and lower limbs in patients with normal pressure hydrocephalus to find a predictor for the success of shunting procedures. The hypotheses that walking disturbances are due to pyramidal tract compression as well as the possibility that the upper limbs are affected subclinically in these patients were also studied. The study suggests that the walking disturbances are not the result of a major pyramidal tract dysfunction but probably involve the sensorimotor integration leading to normal gait. Furthermore, CMCT measured with electromagnetic motor stimulation can help in selecting the patients that will benefit from shunting. The study does not provide electrophysiological evidence of upper limb involvement in normal pressure hydrocephalus. PMID:9153613

  10. Facilitation of motor evoked potentials (MEPs) in first dorsal interosseous (FDI) muscle is dependent on different motor images.

    PubMed

    Yahagi, S; Kasai, T

    1998-10-01

    We investigated changes in motor evoked potentials (MEPs) to explain why mental practice can improve motor performance. MEPs were recorded from right and left first dorsal interosseous (FDI) muscles of 9 normal, right-handed subjects during different motor images of index finger movement: (1) rest, (2) flexion, (3) abduction, (4) extension. A paired t test was used to compare differences of stimulus intensities and MEP amplitudes among conditions. MEP amplitudes significantly increased in both FDI muscles during motor images of flexion and abduction but not of extension. Moreover, MEP amplitudes were larger in flexion than in abduction. These differences were proportional to the amount of real EMG discharge of FDI muscle in the selected direction of index finger movement. With regard to right-left differences, MEP amplitudes in the right FDI muscle were larger than those in the left. The primary motor cortex plays a role in the mental representation of motor acts. Furthermore, the amount of corticomotoneuronal cell activity is affected by the different motor images utilizing the same muscle. Right-left difference of MEP amplitude supports the view of left-hemisphere dominance for motor programming as an aspect of normal brain function among right-handers.

  11. Motor-evoked potentials (MEP) during brainstem surgery to preserve corticospinal function.

    PubMed

    Sarnthein, Johannes; Bozinov, Oliver; Melone, Angelina Graziella; Bertalanffy, Helmut

    2011-09-01

    Brainstem surgery bears a risk of damage to the corticospinal tract (CST). Motor-evoked potentials (MEPs) are used intraoperatively to monitor CST function in order to detect CST damage at a reversible stage and thus impede permanent neurological deficits. While the method of MEP is generally accepted, warning criteria in the context of brainstem surgery still have to be agreed on. We analyzed 104 consecutive patients who underwent microsurgical resection of lesions affecting the brainstem. Motor grade was documented prior to surgery, early postoperatively and at discharge. A baseline MEP stimulation intensity threshold was defined and intraoperative testing aimed to keep MEP response amplitude constant. MEPs were considered deteriorated and the surgical team was notified whenever the threshold was elevated by ≥20 mA or MEP response fell under 50%. On the first postoperative day, 18 patients experienced new paresis that resolved by discharge in 11. MEPs deteriorated in 39 patients, and 16 of these showed new postoperative paresis, indicating a 41% risk of new paresis. In the remaining 2/18 patients, intraoperative MEPs were stable, although new paresis appeared postoperatively. In one of these patients, intraoperative hemorrhage caused postoperative swelling, and the new motor deficit persisted until discharge. Of all 104 patients, 7 deteriorated in motor grade at discharge, 92 remained unchanged, and 5 patients have improved. Adjustment of surgical strategy contributed to good motor outcome in 33/39 patients. MEP monitoring may help significantly to prevent motor deficits during demanding neurosurgical procedures on the brainstem.

  12. The motor evoked potential in AIDS and HAM/TSP: state of the evidence.

    PubMed

    Leon-Sarmiento, Fidias E; Elfakhani, Mohamed; Boutros, Nash N

    2009-12-01

    We aimed to better understand the involvement of the corticospinal tract, assessed by non-invasive transcranial stimulation, in order to determine the actual involvement of the motor system in patients with HAM/TSP and AIDS. An exhaustive MEDLINE search for the period of 1985 to 2008 for all articles cross-referenced for 'HTLV-I, HTLV-II, HTLV-III and HIV, HIV1, HIV2, evoked potential, motor evoked potential, high voltage electrical stimulation, transcranial magnetic stimulation, magnetic stimulation, corticomotor physiology, motor pathways, acquired immunodeficiency syndrome, AIDS, SIDA, tropical spastic paraparesis, HTLV-I-associated myelopathy, HAM, TSP, and HAM/TSP' were selected and analysed. Eighteen papers published in English, Spanish, Portuguese, French and Japanese were identified. Only the central motor conduction time has been analyzed in seropositive patients to human retroviruses. The investigations done on HAM/TSP support the involvement of the pyramidal tract mainly at lower levels, following a centripetal pattern; in AIDS, such an involvement seems to be more prominent at brain levels following a centrifugal pattern. The central motor conduction time abnormalities and involvement differences of the corticospinal tract of patients with AIDS and HAM/TSP dissected here would allow to re-orient early neurorehabilitation measures in these retroviruses-associated neurodegenerative disorders. Besides this, more sophisticated and sensitive non-invasive corticospinal stimulation measures that detect early changes in thalamocortical-basal ganglia circuitry will be needed in both clinically established as well as asymptomatic patients at times when the fastest corticospinal fibers remain uninvolved.

  13. Value of somatosensory and motor evoked potentials in predicting arm recovery after a stroke

    PubMed Central

    Feys, H.; Van Hees, J.; Bruyninckx, F.; Mercelis, R.; De Weerdt, W.

    2000-01-01

    OBJECTIVES—Prediction of motor recovery in the arm in patients with stroke is generally based on clinical examination. However, neurophysiological measures may also have a predictive value. The aims of this study were to assess the role of somatosensory (SSEPs) and motor (MEPs) evoked potentials in the prediction of arm motor recovery and to determine whether these measures added further predictive information to that gained from clinical examination.
METHODS—Sixty four patients who had had a stroke and presented with obvious motor deficit of the arm were examined in terms of three clinical variables (motor performance, muscle tone, and overall disability) and for SSEPs and MEPs. Clinical and neurophysiological examinations were done at entry to the study (2 to 5 weeks poststroke), and at about 2 months after stroke. Further clinical follow up was conducted at 6 and 12 months after stroke.
RESULTS—Neurophysiological measures made in the acute phase were of little use alone in predicting motor recovery of the arm at 2,6, and 12 months after stroke. At 2 months, the absence of SSEPs and MEPs indicated a very poor outcome. Conversely, if the responses were preserved, a great variation in motor outcome was found. Multiple regression analysis showed that the addition of SSEPs and MEPs to the clinical examination increased the possibility of predicting arm recovery in the long term. In the acute phase, the combination of the motor score and SSEPs were best able to predict outcome. The long term outcome based on variables taken at 2 months, was best predicted through incorporating the three clinical measures and MEPs.
CONCLUSIONS—Neurophysiological measures alone are of limited value in predicting long term outcome. However, predictive accuracy is substantially improved through the combined use of both of these measures and clinical variables.

 PMID:10675214

  14. A comparative study of recording procedures for motor evoked potential signals.

    PubMed

    Agrawal, Gracee; Iyer, Shrivats; All, Angelo H

    2009-01-01

    Motor evoked potential (MEP) signals serve as an objective measure of the functional integrity of motor pathways in the spinal cord. Hence, they provide a reliable assessment of the extent of spinal cord injury (SCI). There are two methods currently being used for serial MEP recordings in rats: a low-frequency and a high-frequency method. In this paper, we compared the two methods and determined the better method for MEP recordings. We also compared the effect of two anesthetic agents - inhalational isoflurane and intraperitoneal ketamine - on the MEP signals. We found that under ketamine anesthesia, low-frequency stimulation led to more consistent results, while high-frequency stimulation required greater stimulation intensity and was prone to unwanted side-effects including excessive head twitches. We further found that isoflurane anesthesia severely depressed the MEP response for both low-frequency and high-frequency stimulation which rendered the resulting signal unusable.

  15. Reciprocal facilitation of motor evoked potentials immediately before voluntary movements in Parkinson's disease.

    PubMed

    Imai, T; Yamamoto, T; Ohkubo, Y; Kashiwagi, M; Chiba, S; Matsumoto, H

    1999-06-01

    Changes of motor evoked potentials (MEPs) from the agonist and antagonist forearm muscles were investigated in 13 patients with Parkinson's disease and age-matched controls, in whom transcranial magnetic stimulation (TCMS) was delivered to the cortical hand motor area immediately before voluntary wrist flexion. MEPs recorded from the agonist muscles, namely the wrist flexors, were gradually facilitated in accordance with a shortening of the interval between TCMS and wrist flexion in both groups. In contrast, MEPs recorded from the antagonist muscles, namely the wrist extensors, were gradually facilitated as the intervals were shortened only in parkinsonian patients. The reciprocal facilitation of the antagonist MEPs was statistically significant when TCMS was delivered within 80 msec before the voluntary movements, suggesting the presence of the same underlying mechanism of symptomatic cocontraction observed in patients with Parkinson's disease.

  16. Electromagnetic interference in intraoperative monitoring of motor evoked potentials and a wireless solution.

    PubMed

    Farajidavar, Aydin; Seifert, Jennifer L; Delgado, Mauricio R; Sparagana, Steven; Romero-Ortega, Mario I; Chiao, J-C

    2016-02-01

    Intraoperative neurophysiological monitoring (IONM) is utilized to minimize neurological morbidity during spine surgery. Transcranial motor evoked potentials (TcMEPs) are principal IONM signals in which the motor cortex of the subject is stimulated with electrical pulses and the evoked potentials are recorded from the muscles of interest. Currently available monitoring systems require the connection of 40-60 lengthy lead wires to the patient. These wires contribute to a crowded and cluttered surgical environment, and limit the maneuverability of the surgical team. In this work, it was demonstrated that the cumbersome wired system is vulnerable to electromagnetic interference (EMI) produced by operating room (OR) equipment. It was hypothesized that eliminating the lengthy recording wires can remove the EMI induced in the IONM signals. Hence, a wireless system to acquire TcMEPs was developed and validated through bench-top and animal experiments. Side-by-side TcMEPs acquisition from the wired and wireless systems in animal experiments under controlled conditions (absence of EMI from OR equipment) showed comparable magnitudes and waveforms, thus demonstrating the fidelity in the signal acquisition of the wireless solution. The robustness of the wireless system to minimize EMI was compared with a wired-system under identical conditions. Unlike the wired-system, the wireless system was not influenced by the electromagnetic waves from the C-Arm X-ray machine and temperature management system in the OR. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

  17. [Recommendations for the clinical use of motor evoked potentials in multiple sclerosis].

    PubMed

    Fernández, V; Valls-Sole, J; Relova, J L; Raguer, N; Miralles, F; Dinca, L; Taramundi, S; Costa-Frossard, L; Ferrandiz, M; Ramió-Torrentà, Ll; Villoslada, P; Saiz, A; Calles, C; Antigüedad, A; Alvarez-Cermeño, J C; Prieto, J M; Izquierdo, G; Montalbán, X; Fernández, O

    2013-09-01

    To establish clinical guidelines for the clinical use and interpretation of motor evoked potentials (MEP) in diagnosing and monitoring patients with multiple sclerosis (MS). Recommendations for MEP use and interpretation will help us rationalise and optimise resources used in MS patient diagnosis and follow up. We completed an extensive literature review and pooled our own data to produce a consensus statement with recommendations for the clinical use of MEPs in the study of MS. MEPs, in addition to spinal and cranial magnetic resonance imaging (MRI), help us diagnose and assess MS patients whose disease initially presents as spinal cord syndrome and those with non-specific brain MRI findings, or a normal brain MRI and clinical signs of MS. Whenever possible, a multimodal evoked potential study should be performed on patients with suspected MS in order to demonstrate involvement of the motor pathway which supports a diagnosis of dissemination in space. Copyright © 2012 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

  18. Modulation of Cortical Motor Evoked Potential After Stroke During Electrical Stimulation of the Lateral Cerebellar Nucleus.

    PubMed

    Park, Hyun-Joo; Furmaga, Havan; Cooperrider, Jessica; Gale, John T; Baker, Kenneth B; Machado, Andre G

    2015-01-01

    Deep brain stimulation (DBS) targeting the dentato-thalamo-cortical (DTC) pathway at its origin in the lateral cerebellar nucleus (LCN) has been shown to enhance motor recovery in a rodent model of cortical ischemia. LCN DBS also yielded frequency-specific changes in motor cortex excitability in the normal brain, indexed by motor evoked potential (MEP) amplitude. To investigate the effect of cortical stroke on cortical motor excitability in a rodent ischemia model and to measure the effects of LCN DBS on post-ischemia excitability as a function of stimulation parameters. Adult Sprague-Dawley rats were divided into two groups: naïve and stroke, with cortical ischemia induced through multiple, unilateral endothelin-1 injections. All animals were implanted with a bipolar electrode in the LCN opposite the affected hemisphere. MEPs were elicited from the affected hemisphere using intracortical microstimulation (ICMS) techniques. Multiple LCN DBS parameters were examined, including isochronal stimulation at 20, 30, 50, and 100 Hz as well as a novel burst stimulation pattern. ICMS-evoked MEPs were reduced in stroke (n = 10) relative to naïve (n = 12) animals. However, both groups showed frequency-dependent augmentation of cortical excitability in response to LCN DBS. In the naïve group, LCN DBS increased MEPs by 22-58%, while in the stroke group, MEPs were enhanced by 9-41% compared to OFF-DBS conditions. Activation of the DTC pathway increases cortical excitability in both naïve and post-stroke animals. These effects may underlie, at least partially, functional reorganization and therapeutic benefits associated with chronic LCN DBS in post-stroke animals. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Modulation of cortical motor evoked potential after stroke during electrical stimulation of the lateral cerebellar nucleus

    PubMed Central

    Park, Hyun-Joo; Furmaga, Havan; Cooperrider, Jessica; Gale, John T.; Baker, Kenneth B.; Machado, Andre G.

    2015-01-01

    Background Deep brain stimulation (DBS) targeting the dentato-thalamo-cortical (DTC) pathway at its origin in the lateral cerebellar nucleus (LCN) has been shown to enhance motor recovery in a rodent model of cortical ischemia. LCN DBS also yielded frequency specific changes in motor cortex excitability in the normal brain, indexed by motor evoked potential (MEP) amplitude. Objective To investigate the effect of cortical stroke on cortical motor excitability in a rodent ischemia model and to measure the effects of LCN DBS on post-ischemia excitability as a function of stimulation parameters. Methods Adult Sprague-Dawley rats were divided into two groups: naïve and stroke, with cortical ischemia induced through multiple, unilateral endothelin-1 injections. All animals were implanted with a bipolar electrode in the LCN opposite the affected hemisphere. MEPs were elicited from the affected hemisphere using intracortical microstimulation (ICMS) techniques. Multiple LCN DBS parameters were examined, including isochronal stimulation at 20, 30, 50, and 100 Hz as well as a novel burst stimulation pattern. Results ICMS-evoked MEPs were reduced in stroke (n=10) relative to naïve (n=12) animals. However, both groups showed frequency-dependent augmentation of cortical excitability in response to LCN DBS. In the naïve group, LCN DBS increased MEPs by 22–58%, while in the stroke group, MEPs were enhanced by 9–41% compared to OFF DBS conditions. Conclusions Activation of the DTC pathway increases cortical excitability in both naïve and post-stroke animals. These effects may underlie, at least partially, functional reorganization and therapeutic benefits associated with chronic LCN DBS in post-stroke animals. PMID:26215752

  20. Epidural motor cortex stimulation suppresses somatosensory evoked potentials in the primary somatosensory cortex of the rat.

    PubMed

    Chiou, Ruei-Jen; Lee, Hsiao-Yun; Chang, Chen-Wei; Lin, Kuan-Hung; Kuo, Chung-Chih

    2012-06-29

    Motor cortex stimulation (MCS) is a promising clinical procedure to help alleviate chronic pain. Animal models demonstrated that MCS is effective in lessening nocifensive behaviors. The present study explored the effects of MCS on cortical somatosensory evoked potentials (SEPs) recorded at the primary somatosensory cortex (SI) of the rat. SEPs were evoked by electrical stimulation applied to the contralateral forepaws. Effects of different intensities, frequencies, and durations of MCS were tested. MCS at ≥2V suppressed SEPs of the ipsilateral SI. Suppression lasted 120 min at an intensity of 5 V. The optimal frequency was 50 Hz, and the duration was 30s. In contrast, MCS did not affect SEPs recorded on the contralateral SI. Cortical stimulation out of the motor cortex did not induce a decrease in the ipsilateral SEPs. We also investigated involvement of the endogenous opioid system in this inhibition of SEPs induced by MCS. The opioid antagonist, naloxone (0.5 mg/kg), was administered 30 min before MCS. Application of naloxone completely prevented the inhibitory effect of MCS on ipsilateral SEPs. These results demonstrate that MCS blocked the transmission of somatosensory information to the primary somatosensory cortex, and this interference was mediated by the endogenous opioid system. This inhibitory effect on sensory transmission induced by MCS may reflect its antinociceptive effect.

  1. Concomitant hypertension, bradycardia, and loss of transcranial electric motor evoked potentials during pedicle hook removal: report of a case.

    PubMed

    Ambardekar, A P; Sestokas, A K; Schwartz, D M; Flynn, J M; Rehman, M

    2010-12-01

    Neurophysiologic monitors in the form of transcranial electric motor evoked potentials (tceMEPs) and somatosensory evoked potentials (SSEPs) have become widely used modalities to monitor spinal cord function during major orthopedic spine procedures. In combination with invasive and non-invasive clinical monitoring and an anesthesia information management system (AIMS), we promptly recognized an acute change in hemodynamic and neurophysiologic parameters, managed intraoperative spinal cord contusion, and successfully minimized iatrogenic injury to the spinal cord during corrective spine surgery.

  2. Motor evoked potentials of trunk muscles in traumatic brain injury patients.

    PubMed

    Seo, Min-Ho; Park, Sung-Hee; Ko, Myoung-Hwan; Seo, Jeong-Hwan

    2011-08-01

    To evaluate the motor innervation of trunk muscles in traumatic brain injury patients. Twenty patients (12 men and 8 women) with traumatic brain injury were enrolled in this study. Their mean age was 41 years. Motor evoked potentials (MEPs) were performed on the motor cortex. Electromyographic activities were recorded from the bilateral rectus abdominis muscles, the external oblique abdominal muscles, and the 4th and 9th thoracic erector spinae muscles. The onset latency and amplitude of contralateral and ipsilateral MEPs were measured. All patients were assessed by the Korean version of the Berg Balance Scale (K-BBS) to investigate the relationship between the frequency of MEPs in trunk muscles and gait ability. The mean frequency of ipsilateral MEPs was 23.8% with more damaged hemisphere stimulation, while the contralateral MEPs showed a mean frequency of 47.5% with more damaged hemisphere stimulation in traumatic brain injury patients. The latencies and amplitudes of MEPs obtained from the more damaged hemisphere were not significantly different from those of the less damaged hemisphere. There was no correlation between the manifestation of MEPs in trunk muscles and gait ability. The ipsilateral and contralateral corticospinal pathways to trunk muscles are less likely to be activated in traumatic brain injury patients because of direct injury of the descending corticospinal motor tract or decreased excitability of the corticospinal tract from prefrontal contusion.

  3. Evoked potential studies of the effects of impact acceleration on the motor nervous system.

    PubMed

    Saltzberg, B; Burton, W D; Burch, N R; Ewing, C L; Thomas, D J; Weiss, M; Berger, M D; Jessop, E; Sances, A; Walsh, P R

    1983-12-01

    The initial results of a continuing investigation into the effects of various levels of impact acceleration on the functional integrity of the motor nervous system are summarized. The results are based on the measurement of alterations in neural transmission along the motor pathway of the Rhesus monkey as revealed by latency and amplitude changes in the motor pathway evoked potential (EP) following the delivery of various levels of impact acceleration to a test vehicle. The EPs were produced by electrical stimulation of and recording from the motor pathway of experimental animals subjected to -Y (lateral impact) acceleration and animals subjected to -X (frontal impact) acceleration. High resolution latency and amplitude measures of the EP recorded from these animals before and after impact were tracked so that the time course of recovery of nerve propagation following impact could be accurately assessed. Analysis of these EP measures revealed that the time course of recovery to preimpact values is directly related to the intensity of the acceleration impulse delivered to the test vehicle.

  4. Somatosensory evoked potentials show plastic changes following a novel motor training task with the thumb.

    PubMed

    Andrew, D; Haavik, H; Dancey, E; Yielder, P; Murphy, B

    2015-03-01

    Accumulating evidence indicates that plastic changes can be maladaptive in nature, resulting in movement and neurological disorders. The aim of this study was to further the understanding of these neurophysiological changes in sensorimotor integration (SMI) using somatosensory evoked potentials (SEPs) and concurrent performance changes following a repetitive typing task. SEPs were recorded following median nerve stimulation at the wrist and performed pre and post intervention. 24 participants were randomly assigned to either an intervention group which performed a 20min repetitive typing task or a control group which participated in a 20min period of mental recitation. The P22-N24 amplitude increased by 59.6%, compared to only 0.96% increase following the control. The P22-N30 SEP peak amplitude increased on average 13.4% following the motor training, compared to only 0.92% following the control. Significant improvement in reaction time when comparing performance of the motor task for the intervention group was observed. The N24 increase supports the involvement of cerebellar connections and the N30 increase provides further support for changes in SMI following motor learning. Combining motor training tasks with electrophysiological techniques gives insight into the mechanisms of disordered SMI and whether the changes are adaptive or maladaptive. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  5. Direct motor evoked potentials and cortical mapping using the NIM® nerve monitoring system: A technical note.

    PubMed

    Bharadwaj, Suparna; Haji, Faizal; Hebb, Matthew; Chui, Jason

    2017-04-01

    Motor evoked potentials (MEPs) are commonly used to prevent neurological injury when operating in close proximity to the motor cortex or corticospinal pathway. We report a novel application of the NIM® nerve monitoring system (Medtronic@ NIM response 3.0) for intraoperative direct cortical (dc)-MEPs monitoring. A 69-year-old female patient presented with a 4month history of progressive left hemiparesis resulting from a large right sided posterior frontal meningioma that abutted and compressed the motor cortex. Motor cortical mapping and MEPs were indicated. The patient was anesthetized and maintained on total intravenous anesthetics. Compound muscle action potentials (CMAP) of the right upper limb were monitored using the NIM system. After a craniotomy was performed, we first used the Ojemann stimulator (monopolar) for dc-stimulation and then switched to use the monopolar nerve stimulator probe of the NIM system. The CMAP response was successfully elicited using the NIM stimulating probe (pulse width=250s, train frequency=7pulses/s, current=20mA). A gross total resection of the tumor was achieved with intermittent cortical mapping of MEPs. There were no intraoperative complications and the patient's motor function was preserved after the surgery. In this case, we reported the successful use of the NIM nerve monitoring system to elicit dc-MEPs under general anesthesia. The advantages of using this system include a simple set up and application, neurosurgeon familiarity, wide availability and lower cost. dc-MEPs can be achieved using the NIM system. We conclude that the NIM nerve monitoring system is a feasible alternative to standard neurophysiological monitoring systems.

  6. Neuromodulation of motor-evoked potentials during stepping in spinal rats

    PubMed Central

    Gad, Parag; Lavrov, Igor; Shah, Prithvi; Zhong, Hui; Roy, Roland R.; Gerasimenko, Yury

    2013-01-01

    The rat spinal cord isolated from supraspinal control via a complete low- to midthoracic spinal cord transection produces locomotor-like patterns in the hindlimbs when facilitated pharmacologically and/or by epidural electrical stimulation. To evaluate the role of epidural electrical stimulation in enabling motor control (eEmc) for locomotion and posture, we recorded potentials evoked by epidural spinal cord stimulation in selected hindlimb muscles during stepping and standing in adult spinal rats. We hypothesized that the temporal details of the phase-dependent modulation of these evoked potentials in selected hindlimb muscles while performing a motor task in the unanesthetized state would be predictive of the potential of the spinal circuitries to generate stepping. To test this hypothesis, we characterized soleus and tibialis anterior (TA) muscle responses as middle response (MR; 4–6 ms) or late responses (LRs; >7 ms) during stepping with eEmc. We then compared these responses to the stepping parameters with and without a serotoninergic agonist (quipazine) or a glycinergic blocker (strychnine). Quipazine inhibited the MRs induced by eEmc during nonweight-bearing standing but facilitated locomotion and increased the amplitude and number of LRs induced by eEmc during stepping. Strychnine facilitated stepping and reorganized the LRs pattern in the soleus. The LRs in the TA remained relatively stable at varying loads and speeds during locomotion, whereas the LRs in the soleus were strongly modulated by both of these variables. These data suggest that LRs facilitated electrically and/or pharmacologically are not time-locked to the stimulation pulse but are highly correlated to the stepping patterns of spinal rats. PMID:23761695

  7. Neuromodulation of motor-evoked potentials during stepping in spinal rats.

    PubMed

    Gad, Parag; Lavrov, Igor; Shah, Prithvi; Zhong, Hui; Roy, Roland R; Edgerton, V Reggie; Gerasimenko, Yury

    2013-09-01

    The rat spinal cord isolated from supraspinal control via a complete low- to midthoracic spinal cord transection produces locomotor-like patterns in the hindlimbs when facilitated pharmacologically and/or by epidural electrical stimulation. To evaluate the role of epidural electrical stimulation in enabling motor control (eEmc) for locomotion and posture, we recorded potentials evoked by epidural spinal cord stimulation in selected hindlimb muscles during stepping and standing in adult spinal rats. We hypothesized that the temporal details of the phase-dependent modulation of these evoked potentials in selected hindlimb muscles while performing a motor task in the unanesthetized state would be predictive of the potential of the spinal circuitries to generate stepping. To test this hypothesis, we characterized soleus and tibialis anterior (TA) muscle responses as middle response (MR; 4-6 ms) or late responses (LRs; >7 ms) during stepping with eEmc. We then compared these responses to the stepping parameters with and without a serotoninergic agonist (quipazine) or a glycinergic blocker (strychnine). Quipazine inhibited the MRs induced by eEmc during nonweight-bearing standing but facilitated locomotion and increased the amplitude and number of LRs induced by eEmc during stepping. Strychnine facilitated stepping and reorganized the LRs pattern in the soleus. The LRs in the TA remained relatively stable at varying loads and speeds during locomotion, whereas the LRs in the soleus were strongly modulated by both of these variables. These data suggest that LRs facilitated electrically and/or pharmacologically are not time-locked to the stimulation pulse but are highly correlated to the stepping patterns of spinal rats.

  8. Multi-limb acquisition of motor evoked potentials and its application in spinal cord injury.

    PubMed

    Iyer, Shrivats; Maybhate, Anil; Presacco, Alessandro; All, Angelo H

    2010-11-30

    The motor evoked potential (MEP) is an electrical response of peripheral neuro-muscular pathways to stimulation of the motor cortex. MEPs provide objective assessment of electrical conduction through the associated neural pathways, and therefore detect disruption due to a nervous system injury such as spinal cord injury (SCI). In our studies of SCI, we developed a novel, multi-channel set-up for MEP acquisition in rat models. Unlike existing electrophysiological systems for SCI assessment, the set-up allows for multi-channel MEP acquisition from all limbs of rats and enables longitudinal monitoring of injury and treatment for in vivo models of experimental SCI. The article describes the development of the set-up and discusses its capabilities to acquire MEPs in rat models of SCI. We demonstrate its use for MEP acquisition under two types of anesthesia as well as a range of cortical stimulation parameters, identifying parameters yielding consistent and reliable MEPs. To validate our set-up, MEPs were recorded from a group of 10 rats before and after contusive SCI. Upon contusion with moderate severity (12.5mm impact height), MEP amplitude decreased by 91.36±6.03%. A corresponding decline of 93.8±11.4% was seen in the motor behavioral score (BBB), a gold standard in rodent models of SCI. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Long-latency TMS-evoked potentials during motor execution and inhibition

    PubMed Central

    Kadota, Hiroshi; Nozaki, Daichi

    2013-01-01

    Transcranial magnetic stimulation (TMS) has often been used in conjunction with electroencephalography (EEG), which is effective for the direct demonstration of cortical reactivity and corticocortical connectivity during cognitive tasks through the spatio-temporal pattern of long-latency TMS-evoked potentials (TEPs). However, it remains unclear what pattern is associated with the inhibition of a planned motor response. Therefore, we performed TMS-EEG recording during a go/stop task, in which participants were instructed to click a computer mouse with a right index finger when an indicator that was moving with a constant velocity reached a target (go trial) or to avoid the click when the indicator randomly stopped just before it reached the target (stop trial). Single-pulse TMS to the left (contralateral) or right (ipsilateral) motor cortex was applied 500 ms before or just at the target time. TEPs related to motor execution and inhibition were obtained by subtractions between averaged EEG waveforms with and without TMS. As a result, in TEPs induced by both contralateral and ipsilateral TMS, small oscillations were followed by a prominent negative deflection around the TMS site peaking at approximately 100 ms post-TMS (N100), and a less pronounced later positive component (LPC) over the broad areas that was centered at the midline-central site in both go and stop trials. However, compared to the pattern in go and stop trials with TMS at 500 ms before the target time, N100 and LPC were differently modulated in the go and stop trials with TMS just at the target time. The amplitudes of both N100 and LPC decreased in go trials, while the amplitude of LPC decreased and the latency of LPC was delayed in both go and stop trials. These results suggested that TMS-induced neuronal reactions in the motor cortex and subsequent their propagation to surrounding cortical areas might change functionally according to task demand when executing and inhibiting a motor response. PMID

  10. Task-specific changes in motor evoked potentials of lower limb muscles after different training interventions.

    PubMed

    Beck, S; Taube, W; Gruber, M; Amtage, F; Gollhofer, A; Schubert, M

    2007-11-07

    This study aimed to identify sites and mechanisms of long-term plasticity following lower limb muscle training. Two groups performing either a postural stability maintenance training (SMT) or a ballistic ankle strength training (BST) were compared to a non-training group. The hypothesis was that practicing of a self-initiated voluntary movement would facilitate cortico-spinal projections, while practicing fast automatic adjustments during stabilization of stance would reduce excitatory influence from the primary motor cortex. Training effects were expected to be confined to the practiced task. To test for training specificity, motor evoked potentials (MEP) induced by transcranial magnetic stimulation (TMS) were recorded at rest and during motor tasks that were similar to each training. Intracortical, cortico-spinal, as well as spinal parameters were assessed at rest and during these tasks. The results show high task and training specificity. Training effects were only observable during performance of the trained task. While MEP size was decreased in the SMT group for the trained tasks, MEP recruitment was increased in the BST group in the trained task only. The control group did not show any changes. Background electromyogram levels, M. soleus H-reflex amplitudes and intracortical parameters were unaltered. In summary, it is suggested that the changes of MEP parameters in both training groups, but not in the control group, reflect cortical motor plasticity. While cortico-spinal activation was enhanced in the BST group, SMT may be associated with improved motor control through increased inhibitory trans-cortical effects. Since spinal excitability remained unaltered, changes most likely occur on the supraspinal level.

  11. [Motor cortex stimulation for post-stroke pain using neuronavigation and evoked potentials: report of 3 cases].

    PubMed

    Ito, Masaki; Kuroda, Satoshi; Takano, Kazuya; Maruichi, Katsuhiko; Chiba, Yasuhiro; Morimoto, Yuji; Iwasaki, Yoshinobu

    2006-09-01

    Although motor cortex stimulation (MCS) has been accepted as an effective therapeutic option for central pain, the efficacy of MCS widely varies among previous reports. In this report, we describe our recent trial for successful MCS in 3 patients with central pain due to cerebral stroke. Medical treatments were transiently effective, but gradually became ineffective in all of the cases. During surgery, the appropriate cortical target was determined by using neuronavigation, somatosensory evoked potential (SEP), and motor evoked potential (MEP). A flat, four-plate electrode was positioned on the dura mater parallel to the motor cortex. After surgery, pain almost resolved in 2 of 3 patients and markedly improved in another. The pain relief depended on their motor function. These findings strongly suggest that both patient selection and intraoperative monitoring for targeting the motor cortex are quite important for successful MCS, although further studies were essential.

  12. Motor evoked potentials in a case of stiff-man syndrome: a longitudinal study.

    PubMed

    Logullo, F; Di Bella, P; Provinciali, L

    1999-04-01

    The clinical and neurophysiological findings in a patient with a typical stiff-man syndrome and their three-year evolution are described. The patient had high titers of anti-glutamic acid decarboxylase antibodies in both serum and cerebrospinal fluid. Magnetic resonance imaging (MRI) of brain and spinal cord was normal. Transcranial magnetic stimulation (TMS) revealed a distinctive motor evoked potential (MEP) pattern in proximal lower limb muscles consisting of markedly increased MEP amplitudes and MEP/M ratios, reduced excitability thresholds, and absent silent period. However, MEP latencies, central and peripheral conduction times and amplitudes obtained by magnetic spinal root stimulation were normal. Treatment with benzodiazepine and baclofen normalized both the clinical picture and the MEP values. TMS may be useful both as a diagnostic tool and to monitor the response to drug treatment.

  13. Magnetic resonance imaging and motor-evoked potentials in spinal cord infarction: report of two cases.

    PubMed

    Nardone, Raffaele; Bergmann, Jürgen; Kronbichler, Martin; Lochner, Piergiorgio; Caleri, Francesca; Tezzon, Frediano; Ladurner, Gunther; Golaszewski, Stefan

    2010-08-01

    Because in the early phases of spinal cord ischemia magnetic resonance imaging (MRI) can be normal, its clinical diagnosis is often difficult. We aimed to explore if motor-evoked potentials (MEPs) recordings may contribute to earlier diagnosis of spinal cord stroke. The clinical, MRI, and MEP findings in one case each of cervical and lumbar spinal cord infarction were reported. Spinal MRI at admission was unremarkable in both patients. At this time, MEPs were abnormal in both patients, to the upper and lower limbs in the first patient, exclusively to the lower limbs in the second. Follow-up MRI examinations documented an infarction in the territory of the anterior spinal artery and of the Adamkiewicz artery, respectively. MEP study can be useful in demonstrating spinal cord involvement also when radiological evidence for spinal cord damage is absent or equivocal. Early diagnosis may allow earlier intervention and contribute to improved patient management.

  14. Effects of anesthetic regimens and other confounding factors affecting the interpretation of motor evoked potentials during pediatric spine surgery.

    PubMed

    Balvin, Mark J; Song, Kit M; Slimp, Jefferson C

    2010-09-01

    Children undergoing corrective spine surgery are at risk of serious neurologic injury. Monitoring transcranial electric motor evoked potentials (TCeMEPs) during these procedures may identify and help prevent injury to motor pathways. The difficulty in obtaining consistent motor evoked potential (MEP) responses during pediatric spine surgery can result in part to the suppression of evoked responses caused by volatile inhalational anesthetics, elevated levels of propofol, and/or physiologic variables. Data obtained from 140 pediatric patients who underwent spine surgery with MEP monitoring were retrospectively analyzed and evaluated for age and anesthetic effects on stimulation variables. MEPs acquired under inhalational anesthetic agents required greater stimulation compared to intravenous propofol anesthesia. Additionally, the responses were more variable when inhalational agents were used. These effects were more prominent in younger age patients. The number of alerts of MEP loss or reduction related to anesthetic levels or blood pressure changes was higher under inhalational agents.

  15. Intraoperative Monitoring of Facial Nerve Motor-Evoked Potentials in Children.

    PubMed

    Bozinov, Oliver; Grotzer, Michael A; Sarnthein, Johannes

    2015-09-01

    To determine whether transcranial motor-evoked potential monitoring of the facial nerve (FNMEP) during eloquent tumor resection is feasible in children and can predict both immediate and postoperative facial nerve (FN) function. We included 24 consecutive procedures involving 21 patients (median age 5.5 years, range 5 months to 15 years, 8 female) who were operated on with FNMEP monitoring by the first author in 2013 and 2014. During surgery, we maintained a constant response amplitude by increasing the stimulation intensity and aimed to establish a warning criterion based on the "threshold-level" method. A threshold increase of greater than 20 mA for eliciting the FNMEP in the most reliable facial nerve target muscle was considered to be a prediction of reduced postoperative facial nerve function and consequently, a warning was given to the surgeon. The preoperative and early postoperative function was documented with the House-Brackmann grading system. Monitoring of the FNMEP was feasible in all the surgeries in at least one facial nerve target muscle. The orbicularis oris muscle yielded the best result (95% of the trials), followed by the mentalis (87%) and orbicularis oculi muscles (86%). The median stimulation threshold was initially 65 mA (range 40-110 mA) for the FNMEP and 60 mA (15-220 mA) for the motor-evoked potential of the thenar muscles. The FNMEP deterioration showed a sensitivity of 100% for House-Brackmann deterioration and specificity of 74%. Intraoperative FNMEP monitoring is feasible and safe in infants and children. We found no evidence that the procedures and thresholds should differ from FNMEP monitoring in adults. FNMEP monitoring provides valid evidence for FN function in pediatric eloquent area surgery; its use is complementary to direct electrical FN stimulation and continuous EMG monitoring of FN target muscles. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Intraoperative tractography and motor evoked potential (MEP) monitoring in surgery for gliomas around the corticospinal tract.

    PubMed

    Maesawa, Satoshi; Fujii, Masazumi; Nakahara, Norimoto; Watanabe, Tadashi; Wakabayashi, Toshihiko; Yoshida, Jun

    2010-07-01

    Our goal is to indicate the importance of combining intraoperative tractography with motor-evoked potential (MEP) monitoring for glioma surgery in motor eloquent areas. Tumor removal was performed in 28 patients with gliomas in and around the corticospinal tract (CST), in an operation theater equipped with an integrated high-field intraoperative magnetic resonance imaging and a neuronavigation system. Diffusion-tensor imaging-based tractography of the CST was implemented preoperatively and intraoperatively. When the surgically manipulated area came close to the corticospinal pathway, MEP responses were elicited by subcortical stimulation. Responsive areas were compared with the locations of fibers traced by preoperative and intraoperative tractography. Imaging and functional outcomes were reviewed. Intraoperative tractography demonstrated significant inward or outward shift during surgery. MEP responses were observed around the tract at various intensities, and the distance between MEP responsive sites and intraoperative tractography was significantly correlated with the stimulation intensity (P < 0.01). The distance from preoperative tractography was not correlated. A more than subtotal resection was achieved in 24 patients (85.7%). Transient motor deterioration was seen in 12 patients (42.8%), and a permanent deficit was seen in 1 patient (3.5%). We found that intraoperative tractography demonstrated the location of the CST more accurately than preoperative tractography. The results of the linear regression between distance and stimulation intensity were informative for guiding approaches to tumor remnants without impinging on the CST. The combination of intraoperative tractography and MEP monitoring can enhance the quality of surgery for gliomas in motor eloquent areas. Copyright © 2010 Elsevier Inc. All rights reserved.

  17. Specific neck training induces sustained corticomotor hyperexcitability as assessed by motor evoked potentials.

    PubMed

    Rittig-Rasmussen, Bjarne; Kasch, Helge; Fuglsang-Frederiksen, Anders; Jensen, Troels S; Svensson, Peter

    2013-07-15

    Experimental investigation of short-term and long-term corticomotor effects of specific neck training, coordination training, and no training. To determine the effects of different training programs on the motor neurons controlling the neck muscles as well as the effects of training on muscle strength and muscle fatigue, and the correlations between corticomotor control and motor learning. Training is usually recommended for unspecific neck pain and consists of neck and upper body coordination, strengthening, and endurance exercises. However, it is unclear which type of training is the most effective. No studies have previously investigated the neural effect of neck training and the possible differential effect of specific versus coordination training on corticomotor control. Transcranial magnetic stimulation and electromyography were used to elicit and monitor motor evoked potentials (MEPs) from the trapezius and thumb muscles before and 30 minutes, 1 hour, and 7 days after training. Parameters measured were MEP amplitude, MEP latency, strength, learning effects, and muscle fatigue. Only specific neck training yielded a 67% increase in MEP amplitudes for up to 7 days after training compared with baseline (P < 0.001). No significant changes were seen after coordination training, no training, and in the within-subject control muscle. The mean muscle strength increased immediately after specific neck training from 56.6 to 61 kg (P < 0.001). No subjective or objective measures of fatigue were observed. Specific neck training induced a sustained hyperexcitability of motor neurons controlling the neck muscles compared with coordination training and controls. These findings may prove valuable in the process of developing more effective clinical training programs for unspecific neck pain.

  18. The impact of several craniotomies on transcranial motor evoked potential monitoring during neurosurgery.

    PubMed

    Tomio, Ryosuke; Akiyama, Takenori; Toda, Masahiro; Ohira, Takayuki; Yoshida, Kazunari

    2017-09-01

    OBJECTIVE Transcranial motor evoked potential (tMEP) monitoring is popular in neurosurgery; however, the accuracy of tMEP can be impaired by craniotomy. Each craniotomy procedure and changes in the CSF levels affects the current spread. The aim of this study was to investigate the influence of several craniotomies on tMEP monitoring by using C3-4 transcranial electrical stimulation (TES). METHODS The authors used the finite element method to visualize the electric field in the brain, which was generated by TES, using realistic 3D head models developed from T1-weighted MR images. Surfaces of 5 layers of the head (brain, CSF, skull, subcutaneous fat, and skin layer) were separated as accurately as possible. The authors created 5 models of the head, as follows: normal head; frontotemporal craniotomy; parietal craniotomy; temporal craniotomy; and occipital craniotomy. The computer simulation was investigated by finite element methods, and clinical recordings of the stimulation threshold level of upper-extremity tMEP (UE-tMEP) during neurosurgery were also studied in 30 patients to validate the simulation study. RESULTS Bone removal during the craniotomy positively affected the generation of the electric field in the motor cortex if the motor cortex was just under the bone at the margin of the craniotomy window. This finding from the authors' simulation study was consistent with clinical reports of frontotemporal craniotomy cases. A major decrease in CSF levels during an operation had a significantly negative impact on the electric field when the motor cortex was exposed to air. The CSF surface level during neurosurgery depends on the body position and location of the craniotomy. The parietal craniotomy and temporal craniotomy were susceptible to the effect of the changing CSF level, based on the simulation study. A marked increase in the threshold following a decrease in CSF was actually recorded in clinical reports of the UE-tMEP threshold from a temporal craniotomy

  19. A novel model incorporating two variability sources for describing motor evoked potentials

    PubMed Central

    Goetz, Stefan M.; Luber, Bruce; Lisanby, Sarah H.; Peterchev, Angel V.

    2014-01-01

    Objective Motor evoked potentials (MEPs) play a pivotal role in transcranial magnetic stimulation (TMS), e.g., for determining the motor threshold and probing cortical excitability. Sampled across the range of stimulation strengths, MEPs outline an input–output (IO) curve, which is often used to characterize the corticospinal tract. More detailed understanding of the signal generation and variability of MEPs would provide insight into the underlying physiology and aid correct statistical treatment of MEP data. Methods A novel regression model is tested using measured IO data of twelve subjects. The model splits MEP variability into two independent contributions, acting on both sides of a strong sigmoidal nonlinearity that represents neural recruitment. Traditional sigmoidal regression with a single variability source after the nonlinearity is used for comparison. Results The distribution of MEP amplitudes varied across different stimulation strengths, violating statistical assumptions in traditional regression models. In contrast to the conventional regression model, the dual variability source model better described the IO characteristics including phenomena such as changing distribution spread and skewness along the IO curve. Conclusions MEP variability is best described by two sources that most likely separate variability in the initial excitation process from effects occurring later on. The new model enables more accurate and sensitive estimation of the IO curve characteristics, enhancing its power as a detection tool, and may apply to other brain stimulation modalities. Furthermore, it extracts new information from the IO data concerning the neural variability—information that has previously been treated as noise. PMID:24794287

  20. Analysis of facial motor evoked potentials for assessing a central mechanism in hemifacial spasm.

    PubMed

    Wilkinson, Marshall F; Chowdhury, Tumul; Mutch, W Alan; Kaufmann, Anthony M

    2017-02-01

    OBJECTIVE Hemifacial spasm (HFS) is a cranial nerve hyperactivity disorder characterized by unique neurophysiological features, although the underlying pathophysiology remains disputed. In this study, the authors compared the effects of desflurane on facial motor evoked potentials (MEPs) from the spasm and nonspasm sides of patients who were undergoing microvascular decompression (MVD) surgery to test the hypothesis that HFS is associated with a central elevation of facial motor neuron excitability. METHODS Facial MEPs were elicited in 31 patients who were undergoing MVD for HFS and were administered total intravenous anesthesia (TIVA) with or without additional desflurane, an inhaled anesthetic known to centrally suppress MEPs. All measurements were completed before dural opening while a consistent mean arterial blood pressure was maintained and electroencephalography was performed. The activation threshold voltage and mean amplitudes of the MEPs from both sides of the face were compared. RESULTS There was a significantly lower mean activation threshold of facial MEPs on the spasm side than on the nonspasm side (mean ± SD 162.9 ± 10.1 vs 198.3 ± 10.1 V, respectively; p = 0.01). In addition, MEPs were also elicited more readily when single-pulse transcranial electrical stimulation was used on the spasm side (74% vs 31%, respectively; p = 0.03). Although desflurane (1 minimum alveolar concentration) suppressed facial MEPs on both sides, the suppressive effects of desflurane were less on the spasm side than on the nonspasm side (59% vs 79%, respectively; p = 0.03), and M waves recorded from the mentalis muscle remained unchanged, which indicates that desflurane did not affect the peripheral facial nerve or neuromuscular junction. CONCLUSIONS Centrally acting inhaled anesthetic agents can suppress facial MEPs and therefore might interfere with intraoperative monitoring. The elevated motor neuron excitability and differential effects of desflurane between the spasm

  1. A Preclinical Study of Laryngeal Motor-Evoked Potentials as a Marker Vagus Nerve Activation.

    PubMed

    Grimonprez, Annelies; Raedt, Robrecht; De Taeye, Leen; Larsen, Lars Emil; Delbeke, Jean; Boon, Paul; Vonck, Kristl

    2015-12-01

    Vagus nerve stimulation (VNS) is a treatment for refractory epilepsy and depression. Previous studies using invasive recording electrodes showed that VNS induces laryngeal motor-evoked potentials (LMEPs) through the co-activation of the recurrent laryngeal nerve and subsequent contractions of the laryngeal muscles. The present study investigates the feasibility of recording LMEPs in chronically VNS-implanted rats, using a minimally-invasive technique, to assess effective current delivery to the nerve and to determine optimal VNS output currents for vagal fiber activation. Three weeks after VNS electrode implantation, signals were recorded using an electromyography (EMG) electrode in the proximity of the laryngeal muscles and a reference electrode on the skull. The VNS output current was gradually ramped up from 0.1 to 1.0 mA in 0.1 mA steps. In 13/27 rats, typical LMEPs were recorded at low VNS output currents (median 0.3 mA, IQR 0.2-0.3 mA). In 11/27 rats, significantly higher output currents were required to evoke electrophysiological responses (median 0.7 mA, IQR 0.5-0.7 mA, p < 0.001). The latencies of these responses deviated significantly from LMEPs (p < 0.05). In 3/27 rats, no electrophysiological responses to simulation were recorded. Minimally invasive LMEP recordings are feasible to assess effective current delivery to the vagus nerve. Furthermore, our results suggest that low output currents are sufficient to activate vagal fibers.

  2. Phrenic nerve conduction and diaphragmatic motor evoked potentials: evaluation of respiratory dysfunction.

    PubMed

    Lu, Z; Tang, X; Huang, X

    1998-06-01

    To investigate preliminarily the value of phrenic nerve conduction (PNC) and diaphragmatic motor evoked potentials (MEPs) in the evaluation of various respiratory dysfunction (RDF). Thirty-four patients with various RDF, (19 patients with neurogenical diseases and 15 patients with respiratory disorders) were investigated. Fifty healthy volunteers served as controls. The phrenic nerve was cutaneously stimulated by electrical pulse current at the midpoint of the posterior border of the sternomastoid muscle, and the diaphragmatic muscle compound action potentials (DCAP) were recorded between the 7th and 8th intercostal space and xiphoid process. When the magnetic transcranial stimulation (MTS) of the cortex was given, the recordings were made under the condition of maximal deep inspiration. All patients with myopathies had normal PNC. The patients with Guillain Barre syndrome (GBS), hereditary motor and sensory neuropathy (HMSN) and myasthenic crisis had abnormal PNC. The findings in PNC studies remarkably correlated with RDF, while serial examinations were performed in the patients with GBS and myasthenia gravis (MG). In 7 patients with sleep apnea syndrome (SAS), 4 had abnormal PNC, and 2 of 3 patients with chronic obstructive pulmonary diseases (COPD), and 1 of 5 patients with chest tightness or breathlessness on the supine position showed decreased amplitude. When MEPs were recorded, 3 of 5 patients showed abnormal SAS (1 had no response, 2 lower amplitude). Three patients with COPD had normal MEP. PNC studies could not only evaluate neuromuscular RDF and predict the outcome of diseases, but also supply additional information about diaphragmatic dysfunction for the RDF caused by respiratory disorders. The results of PNC and diaphragmatic MEP may differentiate the types of SAS.

  3. Low-frequency rTMS inhibitory effects in the primary motor cortex: Insights from TMS-evoked potentials.

    PubMed

    Casula, Elias P; Tarantino, Vincenza; Basso, Demis; Arcara, Giorgio; Marino, Giuliana; Toffolo, Gianna Maria; Rothwell, John C; Bisiacchi, Patrizia S

    2014-09-01

    The neuromodulatory effects of repetitive transcranial magnetic stimulation (rTMS) have been mostly investigated by peripheral motor-evoked potentials (MEPs). New TMS-compatible EEG systems allow a direct investigation of the stimulation effects through the analysis of TMS-evoked potentials (TEPs). We investigated the effects of 1-Hz rTMS over the primary motor cortex (M1) of 15 healthy volunteers on TEP evoked by single pulse TMS over the same area. A second experiment in which rTMS was delivered over the primary visual cortex (V1) of 15 healthy volunteers was conducted to examine the spatial specificity of the effects. Single-pulse TMS evoked four main components: P30, N45, P60 and N100. M1-rTMS resulted in a significant decrease of MEP amplitude and in a significant increase of P60 and N100 amplitude. There was no effect after V1-rTMS. 1-Hz rTMS appears to increase the amount of inhibition following a TMS pulse, as demonstrated by the higher N100 and P60, which are thought to originate from GABAb-mediated inhibitory post-synaptic potentials. Our results confirm the reliability of the TMS-evoked N100 as a marker of cortical inhibition and provide insight into the neuromodulatory effects of 1-Hz rTMS. The present finding could be of relevance for therapeutic and diagnostic purposes.

  4. Modulation of amplitude and latency of motor evoked potential by direction of transcranial magnetic stimulation

    NASA Astrophysics Data System (ADS)

    Sato, Aya; Torii, Tetsuya; Iwahashi, Masakuni; Itoh, Yuji; Iramina, Keiji

    2014-05-01

    The present study analyzed the effects of monophasic magnetic stimulation to the motor cortex. The effects of magnetic stimulation were evaluated by analyzing the motor evoked potentials (MEPs). The amplitude and latency of MEPs on the abductor pollicis brevis muscle were used to evaluate the effects of repetitive magnetic stimulation. A figure eight-shaped flat coil was used to stimulate the region over the primary motor cortex. The intensity of magnetic stimulation was 120% of the resting motor threshold, and the frequency of magnetic stimulation was 0.1 Hz. In addition, the direction of the current in the brain was posterior-anterior (PA) or anterior-posterior (AP). The latency of MEP was compared with PA and AP on initial magnetic stimulation. The results demonstrated that a stimulus in the AP direction increased the latency of the MEP by approximately 2.5 ms. MEP amplitude was also compared with PA and AP during 60 magnetic stimulations. The results showed that a stimulus in the PA direction gradually increased the amplitude of the MEP. However, a stimulus in the AP direction did not modulate the MEP amplitude. The average MEP amplitude induced from every 10 magnetic pulses was normalized by the average amplitude of the first 10 stimuli. These results demonstrated that the normalized MEP amplitude increased up to approximately 150%. In terms of pyramidal neuron indirect waves (I waves), magnetic stimulation inducing current flowing backward to the anterior preferentially elicited an I1 wave, and current flowing forward to the posterior elicited an I3 wave. It has been reported that the latency of the I3 wave is approximately 2.5 ms longer than the I1 wave elicitation, so the resulting difference in latency may be caused by this phenomenon. It has also been reported that there is no alteration of MEP amplitude at a frequency of 0.1 Hz. However, this study suggested that the modulation of MEP amplitude depends on stimulation strength and stimulation direction.

  5. Repetitive common peroneal nerve stimulation increases ankle dorsiflexor motor evoked potentials in incomplete spinal cord lesions.

    PubMed

    Thompson, Aiko K; Lapallo, Brandon; Duffield, Michael; Abel, Briana M; Pomerantz, Ferne

    2011-04-01

    Plasticity of corticospinal tract (CST) activity likely plays a key role in motor function recovery after central nervous system (CNS) lesions. In non-injured adults, 30 min of repetitive common peroneal nerve stimulation (rCPnS) increases CST excitability by 40-50% and the effect persists for at least 30 min. The present study evaluated with transcranial magnetic stimulation (TMS) the changes in CST excitability after 30 min of rCPnS in people with foot drop due to incomplete SCI. Suprathreshold rCPnS (25 Hz, alternating 1 s on 1 s off stimulation cycle) was given for two 15-min periods, while the subject sat at rest with ankle and knee joints fixed. Before, between, and after the periods of stimulation, the tibialis anterior (TA) motor evoked potentials (MEPs) to TMS were measured at a TMS intensity that originally produced a half-maximum MEP (typically 10-20% above threshold) while the sitting subject provided 25-30% maximum voluntary TA contraction. In 10 subjects with SCI, the peak-to-peak TA MEP increased by 14 ± 3% after rCPnS and the peak increase (+21 ± 7%) occurred 15 min after the cessation of rCPnS. The TA H-reflex, measured in separate experiments in 7 subjects, did not increase after rCPnS. The results indicate that rCPnS can increase CST excitability for the TA in people with incomplete SCI, although its effects appear smaller and shorter lasting than those found in non-injured control subjects. Such short-term plasticity in the CST excitability induced by rCPnS may contribute to long-term therapeutic effects of functional electrical stimulation previously reported in people with CNS lesions.

  6. [Recovery from rocuronium by sugammadex does not affect motor evoked potentials].

    PubMed

    Hashimoto, Yuko; Gotanda, Yuki; Ito, Takahiko; Ushijima, Kazuo

    2011-08-01

    Motor evoked potential (MEP) monitoring has been employed to detect the spinal cord injury during spinal, neurosurgical and cardiovascular operations. Muscle relaxants diminish the amplitude of MEP because MEP is the picture of electromyogram. In 5 cases undergoing MEP monitoring, we examined the effect of rocuronium followed by the administration of sugammadex on MEP Anesthesia was induced with propofol (target controlled infusion 3.0-3.5 microg x ml(-1)) and remifentanil 0.15-0.3 microg x kg(-1) x min(-1), and the trachea was intubated with the use of rocuronium 0.6 mg x kg(-1) without any muscle rigidity, bucking and laryngospasm. General anesthesia was maintained by total intravenous anesthesia using propofol and remifentanil with no muscle relaxants. Immediately after the tracheal intubation, sugammadex 4 mg x kg(-1) was intravenously given. The amplitude of MEP was measured just before the administration of rocuronium, immediately after the tracheal intubation, and 1, 2, 3, 5 min following the administration of sugammadex. Sugammadex restored the MEP amplitude, deteriorated by rocuronium, in 3 to 5 min to the level of non-paralytic muscles. In one case, it took 8 min to restore the MEP of hemiparetic leg. Taking these findings into consideration, it is likely that rocuronium might not affect the MEP when reversed by sugammadex, and should be safe for smooth tracheal intubation in patients who need MEP monitoring.

  7. Continuous theta burst stimulation of the supplementary motor area: effect upon perception and somatosensory and motor evoked potentials.

    PubMed

    Legon, Wynn; Dionne, Jennifer K; Staines, W Richard

    2013-11-01

    The supplementary motor area (SMA) has been implicated in many aspects of movement preparation and execution. In addition to motor roles, the SMA is responsive to somesthetic stimuli though it is unclear exactly what role the SMA plays in a somatosensory network. It is the purpose of this study to assess how continuous theta burst stimulation (cTBS) of the SMA affects both somatosensory (SEPs) and motor evoked potentials (MEPs) and if cTBS leads to alterations in tactile perception thresholds of the index fingertip. In experiment 1, cTBS was delivered over scalp sites FCZ (SMA stimulation) (n = 10) and CZ (control stimulation) (n = 10) in separate groups for 40 s (600 pulses) at 90% of participants' resting motor threshold. For both groups, median nerve SEPs were elicited from the right wrist at rest via electrical stimulation (0.5 ms pulse) before and at 10 min intervals post-cTBS out to 30 min (t = pre, 10, 20, and 30 min). Subjects' perceptual thresholds were assessed at similar time intervals as the SEP data using a biothesiometer (120 Hz vibration). In experiment 2 (n = 10) the effect of cTBS to SMA upon single and paired-pulse MEP amplitudes from the right first dorsal interosseous (FDI) was assessed. cTBS to scalp site FCZ (SMA stimulation) reduced the frontal N30 SEP and increased tactile perceptual thresholds 30 min post-stimulation. However, parietal SEPs and MEP amplitudes from both single and paired-pulse stimulation were unaffected at all time points post-stimulation. cTBS to stimulation site CZ (control) did not result in any physiological or behavioral changes. These data demonstrate cTBS to the SMA reduces the amplitude of the N30 coincident with an increase in vibration sensation threshold but does not affect primary somatosensory or motor cortex excitability. The SMA may play a significant role in a somatosensory tactile attention network. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. The relationships of motor-evoked potentials to hand dexterity, motor function, and spasticity in chronic stroke patients: a transcranial magnetic stimulation study.

    PubMed

    Cakar, Engin; Akyuz, Gulseren; Durmus, Oguz; Bayman, Levent; Yagci, Ilker; Karadag-Saygi, Evrim; Gunduz, Osman Hakan

    2016-12-01

    The standardization of patient evaluation and monitoring methods has a special importance in evaluating the effectiveness of therapeutic methods using drugs or rehabilitative techniques in stroke rehabilitation. The aim of this study was to investigate the relationships between clinical instruments and transcranial magnetic stimulation (TMS)-evoked neurophysiological parameters in stroke patients. This study included 22 chronic post-stroke patients who were clinically assessed using the Motricity Index (MI), finger-tapping test (FTT), Motor Activity Log (MAL) 28, Brunnstrom motor staging and Ashworth Scale (ASH). Motor-evoked potential (MEP) latency and amplitude, resting motor threshold (rMT) and central motor conduction time (CMCT) were measured with TMS. Shorter MEP-latency, shorter CMCT, higher motor-evoked potential amplitude, and diminished rMT exhibited significant correlations with clinical measures evaluating motor stage, dexterity, and daily life functionality. rMT exhibited a negative correlation with hand and lower extremity Brunnstrom stages (r = -0.64, r = -0.51, respectively), MI score (r = -0.48), FTT score (r = -0.69), and also with amount of use scale and quality of movement scale of MAL 28 scores (r = -0.61, r = -0.62, respectively). Higher MEP amplitude and diminished rMT showed positive correlations with reduced ASH score (r = -0.65, r = 0.44, respectively). The TMS-evoked neurophysiologic parameters including MEP latency, amplitude, rMT and CMCT generally have positive correlation with clinical measures which evaluate motor stage, dexterity and daily life functionality. Additionally, spasticity has also remarkable relationships with MEP amplitude and rMT. These results suggest that TMS-evoked neurophysiological parameters were useful measures for monitoring post-stroke patients.

  9. Change in body surface temperature as an ancillary measurement to motor evoked potentials.

    PubMed

    Yang, J H; Suh, S W; Park, Y-S; Lee, J-H; Park, B K; Ham, C H; Choi, J W

    2015-11-01

    Experimental study. To study the role of surface temperature as an adjunct to motor evoked potentials (MEPs) in rabbit spinal cord injury (SCI) model. Department of Orthopedics, Korea University Guro Hospital, Seoul, Korea. Rabbits (n =18) were divided into Complete (n = 9) and Incomplete (n = 9) SCI groups. Complete SCI was defined as being non-responsive to a wake-up test with loss of MEPs after transection of spinal cord. Incomplete SCI was defined as being responsive to a wake-up test with significant attenuation (⩾ 80%) of MEPs after impaction on spinal cord. Surface temperature of upper and lower extremities, core temperature and MEPs signals were checked before, during and after SCI for 20 min. A wake-up test was conducted and spinal cord was histologicaly evaluated. Experimental conditions between the two groups were statistically similar (P > 0.005 for all values). After SCI, upper extremity temperatures did not change in either group (P > 0.005); however, the surface temperature of the lower extremities in the Complete SCI Group elevated to 1.7 ± 0.5°C in comparison to 0.5 ± 0.1°C in the Incomplete SCI Group (P < 0.001). The scores of wake-up test in the Incomplete SCI Group were significantly different from that of the Complete SCI Group (P < 0.001), while white and gray matter damage was variable on histology. Monitoring of changes of body surface temperature of the lower extremities can be potentially used to identify the completeness of SCI in a rabbit model.

  10. Discrepancy between voluntary movement and motor-evoked potentials in evaluation of motor function during clipping of anterior circulation aneurysms.

    PubMed

    Suzuki, Kengo; Mikami, Takeshi; Sugino, Toshiya; Wanibuchi, Masahiko; Miyamoto, Susumu; Hashimoto, Nobuo; Mikuni, Nobuhiro

    2014-12-01

    Various modalities have been used to confirm the blood flow through parent arteries or surrounding perforating arteries during surgical aneurysm clipping, including motor-evoked potentials (MEPs), Doppler ultrasound, and indocyanine green videoangiography. Nonetheless, contralateral hemiparesis due to arterial blood flow insufficiency may arise because of false-positive or false-negative errors. By performing controlled intraoperative awakening during aneurysm clipping, we compared patients' voluntary movements with simultaneous MEP. Four patients with anterior choroidal artery aneurysms and one patient with a dorsal internal carotid artery aneurysm were included in this study. MEP and intraoperative voluntary movements under awake craniotomy were assessed simultaneously during and after the clipping procedure. Aneurysms were safely and successfully clipped in all patients, with no evidence of postoperative neurological deficits. Voluntary movements and MEP findings did not differ from the control state in three patients. In the other two patients, we observed a discrepancy between MEP amplitudes and voluntary movements. In one patient, deterioration and subsequent improvement in voluntary movements were preceded by MEP amplitude reduction during clipping. In the other patient, MEP amplitude did not change although voluntary movement deteriorated during temporary occlusion of the internal carotid artery. Intraoperative neurological assessment during aneurysmal clipping under awake craniotomy is feasible and safe, and should be valuable for the assessment of ischemia, especially in the anterior choroidal artery. From a neurophysiologic viewpoint, MEP may be insufficiently sensitive for evaluating voluntary movement under ischemia. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Comparison of Motor-Evoked Potentials Versus Somatosensory-Evoked Potentials as Early Indicators of Neural Compromise in Rat Model of Spinal Cord Compression.

    PubMed

    Morris, Susan H; Howard, Jason J; El-Hawary, Ron

    2017-03-15

    Randomized controlled study comparing the efficacy of intraoperative somatosensory-evoked potentials (SSEPs) versus transcranial motor-evoked potentials (TcMEPs) as early indicators of neural compromise and predictors of postoperative function in a rat model of spinal cord compression. To compare the relative efficacy of SSEPs and TcMEPs to detect spinal cord compromise and predict postoperative functional deficit after spinal cord compression. There is controversy regarding the efficacy of SSEPs versus TcMEPs to detect intraoperative spinal cord compromise and predict functional outcomes. Previous trials provide some guidance as to the role of each modality in spinal cord monitoring but randomized controlled trials, which are not feasible in humans, are lacking. Twenty-four adult male Wistar rats were evenly divided into three experimental groups and one control group. The experimental groups were determined according to the length of time that 100% TcMEP signal loss was maintained: 0, 5, or 15 minutes. All animals had standardized preoperative functional testing. Spinal cord compromise was initiated utilizing a validated protocol, which involved compression via a balloon catheter introduced into the thoracic sublaminar space. Both SSEPs and TcMEPs were recorded during cord compression for each experimental group. Functional behavioral testing using two validated methods (tilt and modified Tarlov) was repeated 24 hours after termination of spinal cord compression. Post hoc, animals were redistributed into two functional subgroups, noncompromised and compromised, for statistical analysis. TcMEPs consistently detected spinal cord compromise either in advance of or at the same time as SSEPs; however, the delay in SSEP response was not significant for cases when compromised postoperative function resulted. Both SSEP and TcMEP amplitude recovery correlated well with postoperative functional scores. TcMEPs are more sensitive to spinal cord compromise than SSEPs, but the

  12. Transcranial motor evoked potential waveform changes in corrective fusion for adolescent idiopathic scoliosis.

    PubMed

    Kobayashi, Kazuyoshi; Imagama, Shiro; Ito, Zenya; Ando, Kei; Hida, Tetsuro; Ito, Kenyu; Tsushima, Mikito; Ishikawa, Yoshimoto; Matsumoto, Akiyuki; Nishida, Yoshihiro; Ishiguro, Naoki

    2017-01-01

    OBJECTIVE Corrective surgery for spinal deformities can lead to neurological complications. Several reports have described spinal cord monitoring in surgery for spinal deformity, but only a few have included patients younger than 20 years with adolescent idiopathic scoliosis (AIS). The goal of this study was to evaluate the characteristics of cases with intraoperative transcranial motor evoked potential (Tc-MEP) waveform deterioration during posterior corrective fusion for AIS. METHODS A prospective database was reviewed, comprising 68 patients with AIS who were treated with posterior corrective fusion in a prospective database. A total of 864 muscles in the lower extremities were chosen for monitoring, and acceptable baseline responses were obtained from 819 muscles (95%). Intraoperative Tc-MEP waveform deterioration was defined as a decrease in intraoperative amplitude of ≥ 70% of the control waveform. Age, Cobb angle, flexibility, operative time, estimated blood loss (EBL), intraoperative body temperature, blood pressure, number of levels fused, and correction rate were examined in patients with and without waveform deterioration. RESULTS The patients (3 males and 65 females) had an average age of 14.4 years (range 11-19 years). The mean Cobb angles before and after surgery were 52.9° and 11.9°, respectively, giving a correction rate of 77.4%. Fourteen patients (20%) exhibited an intraoperative waveform change, and these occurred during incision (14%), after screw fixation (7%), during the rotation maneuver (64%), during placement of the second rod after the rotation maneuver (7%), and after intervertebral compression (7%). Most waveform changes recovered after decreased correction or rest. No patient had a motor deficit postoperatively. In multivariate analysis, EBL (OR 1.001, p = 0.085) and number of levels fused (OR 1.535, p = 0.045) were associated with waveform deterioration. CONCLUSIONS Waveform deterioration commonly occurred during rotation maneuvers

  13. Transoesophageal spinal cord stimulation for motor-evoked potentials monitoring: feasibility, safety and stability.

    PubMed

    Tsuda, Kazumasa; Shiiya, Norihiko; Takahashi, Daisuke; Ohkura, Kazuhiro; Yamashita, Katsushi; Kando, Yumi

    2015-08-01

    Specificity of transcranial motor-evoked potentials (MEPs) is low because amplitude fluctuation is common, which seems due to several technical and fundamental reasons including difficulty in electrodes positioning and fixation for transcranial stimulation and susceptibility to anaesthesia. This study aimed to investigate the feasibility, safety and stability of our novel technique of transoesophageal spinal cord stimulation to improve the stability of MEPs. Ten anaesthetized adult beagle dogs were used. Transoesophageal stimulation was performed between the oesophageal luminal surface electrode (cathode) and a subcutaneous needle electrode (anode) at the fourth to fifth thoracic vertebra level. Stimulation was achieved with a train of five pulses delivered at 2.0-ms intervals. Compound muscle action potentials were recorded from four limbs and external anal sphincter muscles. Stability to anaesthetic agents was tested at varying speeds of propofol and remifentanil, and effects of varying concentration of sevoflurane inhalation were also evaluated. Transoesophageal MEPs could be recorded without difficulty in all dogs. Fluoroscopic evaluation showed that electrodes misalignment up to 5 cm cranially or caudally could be tolerated. Stimulus intensity to achieve maximum amplitude of hindlimb muscle potentials on both sides was significantly lower by transoesophageal stimulation than by transcranial stimulation (383 ± 41 vs 533 ± 121 V, P = 0.02) and had less interindividual variability. Latency of transoesophageal MEPs was shorter than that of transcranial MEPs at every recording point. No arrhythmia was provoked during stimulation. Animals that were allowed to recover showed no neurological abnormality. In the two sacrificed animals, the explanted oesophagus showed no mucosal injury. Stability to varying dose of anaesthetic agents was similar between transoesophageal and transcranial stimulation, except for the potentials of forelimbs by transoesophageal

  14. Comparison of Diffusion Tensor Tractography and Motor Evoked Potentials for the Estimation of Clinical Status in Subacute Stroke.

    PubMed

    Chun, Kwang-Soo; Lee, Yong-Taek; Park, Jong-Wan; Lee, Joon-Youn; Park, Chul-Hyun; Yoon, Kyung Jae

    2016-02-01

    To compare diffusion tensor tractography (DTT) and motor evoked potentials (MEPs) for estimation of clinical status in patients in the subacute stage of stroke. Patients with hemiplegia due to stroke who were evaluated using both DTT and MEPs between May 2012 and April 2015 were recruited. Clinical assessments investigated upper extremity motor and functional status. Motor status was evaluated using Medical Research Council grading and the Fugl-Meyer Assessment of upper limb and hand (FMA-U and FMA-H). Functional status was measured using the Modified Barthel Index (MBI). Patients were classified into subgroups according to DTT findings, MEP presence, fractional anisotropy (FA) value, FA ratio (rFA), and central motor conduction time (CMCT). Correlations of clinical assessments with DTT parameters and MEPs were estimated. Fifty-five patients with hemiplegia were recruited. In motor assessments (FMA-U), MEPs had the highest sensitivity and negative predictive value (NPV) as well as the second highest specificity and positive predictive value (PPV). CMCT showed the highest specificity and PPV. Regarding functional status (MBI), FA showed the highest sensitivity and NPV, whereas CMCT had the highest specificity and PPV. Correlation analysis showed that the resting motor threshold (RMT) ratio was strongly associated with motor status of the upper limb, and MEP parameters were not associated with MBI. DTT and MEPs could be suitable complementary modalities for analyzing the motor and functional status of patients in the subacute stage of stroke. The RMT ratio was strongly correlated with motor status.

  15. Origin of facilitation of motor-evoked potentials after paired magnetic stimulation: direct recording of epidural activity in conscious humans.

    PubMed

    Di Lazzaro, V; Pilato, F; Oliviero, A; Dileone, M; Saturno, E; Mazzone, P; Insola, A; Profice, P; Ranieri, F; Capone, F; Tonali, P A; Rothwell, J C

    2006-10-01

    A magnetic transcranial conditioning stimulus given over the motor cortex at intensities below active threshold for obtaining motor-evoked potentials (MEPs) facilitates EMG responses evoked at rest in hand muscles by a suprathreshold magnetic stimulus given 10-25 ms later. This is known as intracortical facilitation (ICF). We recorded descending volleys produced by single and paired magnetic motor cortex stimulation through high cervical epidural electrodes implanted for pain relief in six conscious patients. At interstimulus intervals (ISIs) of 10 and 15 ms, although MEP was facilitated, there was no change in the amplitude or number of descending volleys. An additional I wave sometimes was observed at 25 ms ISI. In one subject, we also evaluated the effects of reversing the direction of the induced current in the brain. At 10 ms ISI, the facilitation of the MEPs disappeared and was replaced by slight suppression; at 2 ms ISI, there was a pronounced facilitation of epidural volleys. Subsequent experiments on healthy subjects showed that a conditioning stimulus capable of producing ICF of MEPs had no effect on the EMG response evoked by transmastoidal electrical stimulation of corticospinal tract. We conclude that ICF occurs because either 1) the conditioning stimulus has a (thus far undetected) effect on spinal cord excitability that increases its response to the same amplitude test volley or 2) that it can alter the composition (but not the amplitude) of the descending volleys set up by the test stimulus such that a larger proportion of the activity is destined for the target muscle.

  16. Use of magnetic stimulation to elicit motor evoked potentials, somatosensory evoked potentials, and H-reflexes in non-sedated rodents.

    PubMed

    Zhang, Yi Ping; Shields, Lisa B E; Zhang, Yongjie; Pei, Jiong; Xu, Xiao-Ming; Hoskins, Rachel; Cai, Jun; Qiu, Meng Sheng; Magnuson, David S K; Burke, Darlene A; Shields, Christopher B

    2007-09-15

    Assessment of locomotor function of rodents may be supplemented using electrophysiological tests which monitor the integrity of ascending and descending tracts as well as the focal circuitry of the spinal cord in non-sedated rodents. Magnetically induced SSEPs (M-SSEPs) were elicited in rats by activating the hindpaw using magnetic stimulation (MS). M-SSEP response latencies were slightly longer than those elicited by electrical stimulation. M-SSEPs were eliminated following selective dorsal column lacerations of the spinal cord, indicating that they were transmitted via this tract. Magnetically induced motor evoked potentials (M-MEPs) were elicited in mice following transcranial MS and recorded from the gastrocnemius muscles. M-MEPs performed on myelin deficient mice demonstrated longer onset latencies and smaller amplitudes than in wild-type mice. Magnetically induced H-reflexes (MH-reflexes) which assess local circuitry in the lumbosacral area of the spinal cord were performed in rats. This response disappeared following an L3 contusion spinal cord injury, however, kainic acid (KA) injection at L3, known to selectively destroy interneurons, caused a shorter latency and an increase in the amplitude of the MH-reflex. M-SSEPs and MH-reflexes in rats and M-MEPs in mice compliment locomotor evaluation in assessing the functional integrity of the spinal cord under normal and pathological conditions in the non-sedated animal.

  17. Ischemic Cervical Myelopathy Caused by Vertebral Artery Dissection: The Clinical Utility of a Motor-evoked Potential Study.

    PubMed

    Lee, Woo Hyung; Lee, Shi-Uk; Jung, Se Hee

    2016-01-01

    Vertebral artery dissection (VAD) has been increasingly recognized as one of the important causes of ischemic stroke especially in young and middle-aged population. Rarely, VAD can involve the spinal cord, causing ischemic cervical myelopathy. A 51-year-old man presented with sudden onset of weakness and hypesthesia involving right upper extremity, accompanied by posterior neck pain and headache. He also complained nonwhirling type of dizziness and nausea and he exhibited ataxic gait. Brain magnetic resonance imaging showed acute infarction at the right cerebellar hemisphere and temporo-occipital lobe. Right VAD was identified by MR angiography and confirmed by transfemoral cerebral angiography. Because the selective proximal weakness of the right upper extremity and hypesthesia at C5 and C6 dermatomes was not be fully explained by the brain lesion, electrophysiological studies were performed. The motor-evoked potential studies revealed that the latency and central motor conduction time was prolonged in the right cervical and lumbosacral roots. These studies implied cervical myelopathy involving the right anterior column. Magnetic resonance imaging of the cervical spine demonstrated high signal intensity of the right anterior column at C3-C4 level, which confirmed cervical ischemic myelopathy. When there is diagnostic ambiguity between the upper and lower motor neuron lesions in VAD, motor-evoked potential study can be helpful to diagnose peripheral neurological complication of VAD.

  18. Motor evoked potentials after transcranial magnetic stimulation support hypothesis of coexisting central mechanism in obstetric brachial palsy.

    PubMed

    Colon, A J; Vredeveld, J W; Blaauw, G

    2007-02-01

    Six infants with obstetric brachial palsy, ranging from 4 to 7 months of age, were investigated. One was suspected of having extensive brachial plexus lesions and five were suspected of having a unilateral lesion of both roots C5 and C6. All were referred to our center to investigate the possibility for reconstructive surgery. In all infants, even at this age, transcranial magnetic stimulation resulted in motor evoked potentials (MEP) in the biceps (in one, in the brachioradial) muscles. Averaging could not be done because of the intraindividual variation in latency. The MEP was easier to recognize if evoked when the infant had the arm bent. In all five infants suspected of upper brachial plexus lesion with avulsion of both roots C5 and C6 and/or complete rupture of the upper trunk, proven in four, an MEP on the lesioned side could be evoked. Combined with earlier investigations showing (almost) normal EMG and somatosensory evoked potentials in infants with upper plexus lesion, this leads us to the conclusion that the paralysis of these infants cannot only be attributed to the peripheral axonal damage alone but that central plasticity must also play an important role. As this is a slow process, some infants might not yet be able to use the paralytic muscles. Some theoretic issues are discussed.

  19. Significance of intraoperative motor function monitoring using transcranial electrical motor evoked potentials (MEP) in patients with spinal and cranial lesions near the motor pathways.

    PubMed

    Krammer, Matthias Johannes; Wolf, Stefan; Schul, David Baruch; Gerstner, Werner; Lumenta, Christianto Bernardo

    2009-02-01

    Intraoperative motor evoked potential (MEP) monitoring in patients with spinal and cranial lesions is thought to be a valuable tool for prevention of postoperative motor deficits. Aim of this study was to investigate its diagnostic value in a spinal and a cranial patient group. Ninety-six patients, 31 with spinal and 65 with intracranial lesions, were studied. Transcranial stimulation was performed with a high-frequency electrical train stimulation using two subdermal needle electrodes. MEPs were recorded from the pathology-related muscles. Decreasing amplitudes of 50% or more, increasing stimulus intensities of 20% or more or increased latencies were taken as warning criteria. MEP recording was possible in 90% of the spinal and 98% of the cranial group. With two further exclusions, 28 patients of the spinal and 62 of the cranial group were analyzed. We saw a temporary maximum amplitude reduction of 50% or more and an increase in stimulation intensity of 20% or more in 8 spinal and 29 cranial patients. Five of the spinal and nine of the cranial patients deteriorated in motor function postoperatively. One patient with normal MEP monitoring showed a temporary motor weakness postoperatively. Latencies were normal in all patients. Given both warning criteria, intraoperative MEP changes had a sensitivity of 83%/ 100% and a specificity of 86%/ 62% (spinal/ cranial group). The positive predictive value of MEP changes for postoperative motor function deterioration was 63%/ 31%, and the negative predictive value was 95%/ 100%. Transcranial electrical monitoring of MEP is a practicable and safe method. However, there are many events, which can cause amplitude changes of MEP independent from surgical manipulations. Although sensitivity is high for both groups, this results in a moderate specificity for the cranial group and a low positive predictive value for both groups.

  20. The need to add motor evoked potential monitoring to somatosensory and electromyographic monitoring in cervical spine surgery

    PubMed Central

    Epstein, Nancy E.

    2013-01-01

    Intraoperative neural monitoring (IONM), utilizing somatosensory evoked potentials (SEP) and electromyography (EMG), was introduced to cervical spine surgery in the late 1980's. However, as SEP only provided physiological data regarding the posterior cord, new motor deficits were observed utilizing SEP alone. This prompted the development of motor evoked potential monitoring (MEP) which facilitated real-time assessment of the anterior/anterolateral spinal cord. Although all three modalities, SEP, EMG, and MEP, are routinely available for IONM of cervical spine procedures, MEP are not yet routinely employed. The purpose of this review is to emphasize that MEP should now routinely accompany SEP and EMG when performing IONM of cervical spine surgery. Interestingly, one of the most common reasons for malpractice suits involving the cervical spine, is quadriparesis/quadriplegia following a single level anterior cervical diskectomy and fusion (ACDF). Previously, typical allegations in these suits included; negligent surgery, lack of informed consent, failure to diagnose/treat, and failure to brace. Added to this list, perhaps, as the 5th most reason for a suit will be failure to monitor with MEP. This review documents the value of MEP monitoring in addition to SEP and EMG monitoring in cervical spine surgery. The addition of MEP0 should minimize major motor injuries, and more accurately and reliably detect impending anterior cord deterioration that may be missed with SEP monitoring alone. PMID:24340237

  1. Safe transcranial electric stimulation motor evoked potential monitoring during posterior spinal fusion in two patients with cochlear implants.

    PubMed

    Yellin, Joseph L; Wiggins, Cheryl R; Franco, Alier J; Sankar, Wudbhav N

    2016-08-01

    Transcranial electric stimulation (TES) motor evoked potentials (MEPs) have become a regular part of intraoperative neurophysiologic monitoring (IONM) for posterior spinal fusion (PSF) surgery. Almost all of the relative contraindications to TES have come and gone. One exception is in the case of patients with a cochlear implant (CI). Herein we illustrate two cases of pediatric patients with CIs who underwent PSF using TES MEPs as part of IONM. In both instances the patients displayed no untoward effects from TES, and post-operatively both CIs were intact and functioning as they were prior to surgery.

  2. Comparison of Diffusion Tensor Tractography and Motor Evoked Potentials for the Estimation of Clinical Status in Subacute Stroke

    PubMed Central

    Chun, Kwang-Soo; Lee, Yong-Taek; Park, Jong-Wan; Lee, Joon-Youn; Park, Chul-Hyun

    2016-01-01

    Objective To compare diffusion tensor tractography (DTT) and motor evoked potentials (MEPs) for estimation of clinical status in patients in the subacute stage of stroke. Methods Patients with hemiplegia due to stroke who were evaluated using both DTT and MEPs between May 2012 and April 2015 were recruited. Clinical assessments investigated upper extremity motor and functional status. Motor status was evaluated using Medical Research Council grading and the Fugl-Meyer Assessment of upper limb and hand (FMA-U and FMA-H). Functional status was measured using the Modified Barthel Index (MBI). Patients were classified into subgroups according to DTT findings, MEP presence, fractional anisotropy (FA) value, FA ratio (rFA), and central motor conduction time (CMCT). Correlations of clinical assessments with DTT parameters and MEPs were estimated. Results Fifty-five patients with hemiplegia were recruited. In motor assessments (FMA-U), MEPs had the highest sensitivity and negative predictive value (NPV) as well as the second highest specificity and positive predictive value (PPV). CMCT showed the highest specificity and PPV. Regarding functional status (MBI), FA showed the highest sensitivity and NPV, whereas CMCT had the highest specificity and PPV. Correlation analysis showed that the resting motor threshold (RMT) ratio was strongly associated with motor status of the upper limb, and MEP parameters were not associated with MBI. Conclusion DTT and MEPs could be suitable complementary modalities for analyzing the motor and functional status of patients in the subacute stage of stroke. The RMT ratio was strongly correlated with motor status. PMID:26949679

  3. Repetition suppression in transcranial magnetic stimulation-induced motor-evoked potentials is modulated by cortical inhibition.

    PubMed

    Kallioniemi, E; Pääkkönen, A; Julkunen, P

    2015-12-03

    Transcranial magnetic stimulation (TMS) can be applied to modulate cortical phenomena. The modulation effect is dependent on the applied stimulation frequency. Repetition suppression (RS) has been demonstrated in the motor system using TMS with short suprathreshold 1-Hz stimulation trains repeated at long inter-train intervals. RS has been reported to occur in the resting motor-evoked potentials (MEPs) with respect to the first pulse in a train of stimuli. Although this RS in the motor system has been described in previous studies, the neuronal origin of the phenomenon is still poorly understood. The present study evaluated RS in three TMS-induced motor responses; resting and active MEPs as well as corticospinal silent periods (SPs) in order to clarify the mechanism behind TMS-induced RS. We studied 10 healthy right-handed subjects using trains of four stimuli with stimulation intensities of 120% of the resting motor threshold (rMT) and 120% of the silent period threshold for an SP duration of 30 ms (SPT30). Inter-trial interval was 20s, with a 1-s inter-stimulus interval within the trains. We confirmed that RS appears in resting MEPs (p < 0.001), whereas active MEPs did not exhibit RS (p > 0.792). SPs, on the contrary, lengthened (p < 0.001) indicating modulation of cortical inhibition. The effects of the two stimulation intensities exhibited a similar trend; however, the SPT30 evoked a more profound inhibitory effect compared to that achieved by rMT. Moreover, the resting MEP amplitudes and SP durations correlated (rho ⩽ -0.674, p < 0.001) and the pre-TMS EMG level did not differ between stimuli in resting MEPs (F = 0.0, p ⩾ 0.999). These results imply that the attenuation of response size seen in resting MEPs might originate from increasing activity of inhibitory GABAergic interneurons which relay the characteristics of SPs.

  4. Age-dependent decline in motor evoked potential (MEP) amplitude: with a comment on changes in Parkinson's disease.

    PubMed

    Eisen, A; Siejka, S; Schulzer, M; Calne, D

    1991-06-01

    Peak-to-peak measurement of the maximum amplitude motor evoked potential (MAXMEP) elicited by 20 consecutive transcranial magnetic stimuli recorded from the contracting thenar and hypothenar muscles measured 9.8 +/- 2.0 mV and 7.25 +/- 2.9 mV respectively (P less than 0.01). The ratio of MAXMEP/CMAP measured 92.6 +/- 25.8% and 54.8 +/- 12.3% respectively (P less than 0.001). Repeat studies showed good individual reproducibility. Amplitudes declined linearly with age (r = -0.836 for thenar MAXMEP P less than 0.001). It is argued that MAXMEP related to age is more meaningful than the MEP/CMAP wave ratio and is proportional to the number of fast conducting cortical motor neurons excited. In 7/18 patients with Parkinson's disease (PD) MAXMEP was increased; in 2 other patients MAXMEP was decreased for their age.

  5. Augmentation of motor evoked potentials using multi-train transcranial electrical stimulation in intraoperative neurophysiologic monitoring during spinal surgery.

    PubMed

    Tsutsui, Shunji; Iwasaki, Hiroshi; Yamada, Hiroshi; Hashizume, Hiroshi; Minamide, Akihito; Nakagawa, Yukihiro; Nishi, Hideto; Yoshida, Munehito

    2015-02-01

    Transcranial motor evoked potentials (TcMEPs) are widely used to monitor motor function during spinal surgery. Improvements in transcranial stimulation techniques and general anesthesia have made it possible to record reliable and reproducible potentials. However, TcMEPs are much smaller in amplitude compared with compound muscle action potentials (CMAPs) evoked by maximal peripheral nerve stimulation. In this study, multi-train transcranial electrical stimulation (mt-TES) was introduced to enhance TcMEPs, and the optimal setting of mt-TES was investigated. In 30 patients undergoing surgical correction of spinal deformities (4 males and 26 females with normal motor status; age range 11-75 years), TcMEPs from the abductor hallucis (AH) and quadriceps femoris (QF) were analyzed. A multipulse (train) stimulus with an individual pulse width of 0.5 ms and an inter-pulse interval of 2 ms was delivered repeatedly (2-7 times) at different rates (2, 5, and 10 Hz). TcMEP amplitudes increased with the number of train stimuli for AH, with the strongest facilitation observed at 5 Hz. The response amplitude increased 6.1 times on average compared with single-train transcranial electrical stimulation (st-TES). This trend was also observed in the QF. No adverse events (e.g., seizures, cardiac arrhythmias, scalp burns, accidental injury resulting from patient movement) were observed in any patients. Although several facilitative techniques using central or peripheral stimuli, preceding transcranial electrical stimulation, have been recently employed to augment TcMEPs during surgery, responses are still much smaller than CMAPs. Changing from conventional st-TES to mt-TES has potential to greatly enhance TcMEP responses.

  6. The hybrid BCI system for movement control by combining motor imagery and moving onset visual evoked potential

    NASA Astrophysics Data System (ADS)

    Ma, Teng; Li, Hui; Deng, Lili; Yang, Hao; Lv, Xulin; Li, Peiyang; Li, Fali; Zhang, Rui; Liu, Tiejun; Yao, Dezhong; Xu, Peng

    2017-04-01

    Objective. Movement control is an important application for EEG-BCI (EEG-based brain–computer interface) systems. A single-modality BCI cannot provide an efficient and natural control strategy, but a hybrid BCI system that combines two or more different tasks can effectively overcome the drawbacks encountered in single-modality BCI control. Approach. In the current paper, we developed a new hybrid BCI system by combining MI (motor imagery) and mVEP (motion-onset visual evoked potential), aiming to realize the more efficient 2D movement control of a cursor. Main result. The offline analysis demonstrates that the hybrid BCI system proposed in this paper could evoke the desired MI and mVEP signal features simultaneously, and both are very close to those evoked in the single-modality BCI task. Furthermore, the online 2D movement control experiment reveals that the proposed hybrid BCI system could provide more efficient and natural control commands. Significance. The proposed hybrid BCI system is compensative to realize efficient 2D movement control for a practical online system, especially for those situations in which P300 stimuli are not suitable to be applied.

  7. Awake far lateral craniotomy for resection of foramen magnum meningioma in a patient with tenuous motor and somatosensory evoked potentials.

    PubMed

    deipolyi, Amy R; Han, Seunggu J; Sughrue, Michael E; Litt, Lawrence; Parsa, Andrew T

    2011-09-01

    We report a patient with an infratentorial lesion resected under a far-lateral approach during awake craniotomy to optimize intraoperative monitoring. A 72-year-old man presented with falls, difficulty walking, and lower extremity weakness. MRI revealed a 2.2 by 2.3 by 2.8 cm mass at the right cervicomedullary junction, with mass effect on the adjacent spinal cord. During two attempts during surgical positioning under general anesthesia, motor evoked potentials were lost. Each time the operation was aborted. During the third operation, the patient underwent monitored, light anaesthesia and was awakened periodically to confirm conscious motor function. The operation proceeded without complication, and postoperatively there was no further decrease in motor function. This is, to our knowledge, the first use of an awake operation for an infratentorial meningioma via the far-lateral approach, demonstrating the technique may be used safely and can be useful in optimizing motor function monitoring. Copyright © 2011. Published by Elsevier Ltd.

  8. Effect of cued training on motor evoked potential and cortical silent period in people with Parkinson's disease.

    PubMed

    Mak, Margaret; Hallett, Mark

    2013-03-01

    To examine whether training under visual cues could enhance motor cortical excitability and intracortical inhibition in individuals with Parkinson's disease (PD). This was a single blinded cross-over study. Eight individuals with PD received two sessions of 30-min pinch-grip training with and without visual cues. The visual cue was given in form of an arrow that indicated the pre-set force level on a computer screen. Outcome measures consisted of peak motor evoked potential (MEP) and cortical silent period (CSP) of the first dorsal interosseus as well as behavioural tests including Purdue pegboard test, tapping speed in 30s, and the maximum pinch grip force exerted by the thumb and index finger. After cued training, there were significant increases in the peak MEP, CSP duration and tapping speed (all p<0.05). In contrast, there was no change in all outcome measures after training under the non-cued condition. Thirty minutes of pinch-grip training with visual cues could enhance motor cortical excitability and intracortical inhibition in individuals with PD. The findings on the neurophysiological changes after cued-training may inform further clinical application of visual cues to maximize motor improvement and corticomotor plasticity in people with PD. Copyright © 2012 International Federation of Clinical Neurophysiology. All rights reserved.

  9. Asymmetry of magnetic motor evoked potentials recorded in calf muscles of the dominant and non-dominant lower extremity.

    PubMed

    Olex-Zarychta, Dorota; Koprowski, Robert; Sobota, Grzegorz; Wróbel, Zygmunt

    2009-08-07

    The aim of the study was to determine the applicability of magnetic stimulation and magnetic motor evoked potentials (MEPs) in motor asymmetry studies by obtaining quantitative and qualitative measures of efferent activity during low intensity magnetic stimulation of the dominant and non-dominant lower extremities. Magnetic stimulation of the tibial nerve in the popliteal fossa was performed in 10 healthy male right-handed and right-footed young adults. Responses were recorded from the lateral head of the gastrocnemius muscles of the right and left lower extremities. Response characteristics (duration, onset latency, amplitude) were analyzed in relation to the functional dominance of the limbs and in relation to the direction of the current in the magnetic coil by use of the Wilcoxon pair sequence test. The CCW direction of coil current was related to reduced amplitudes of recorded MEPs. Greater amplitudes of evoked potentials were recorded in the non-dominant extremity, both in the CW and CCW coil current directions, with the statistical significance of this effect (p=0.005). No differences in duration of response were found in the CW current direction, while in CCW the time of the left-side response was prolonged (p=0.01). In the non-dominant extremity longer onset latencies were recorded in both current directions, but only for the CW direction the side asymmetries showed a statistical significance of p=0.005. In the dominant extremity the stimulation correlated with stronger paresthesias, especially using the CCW direction of coil current. The results indicate that low intensity magnetic stimulation may be useful in quantitative and qualitative research into the motor asymmetry.

  10. Early somatosensory evoked potentials.

    PubMed

    Sances, A; Larson, S J; Cusick, J F; Myklebust, J; Ewing, C L; Jodat, R; Ackmann, J J; Walsh, P

    1978-10-01

    The early somatosensory evoked potential secondary to median nerve stimulation in the human had an onset latency of 9--12 msec when recorded from scalp electrodes at vertex-to-mastoid, vertex-to-inion or at the base of the skull. Similar latencies were observed from responses recorded over the cervical dorsal columns during neurologic surgery. A latency difference of 1.5 msec was observed between the early response and the responses recorded from the junction of medial lemniscus and nucleus ventralis posterior lateralis of the thalamus during human stereotaxic surgery. Cervical cord transections and transection at the midpontine levels of the monkey showed that the evoked potential was due to generators between these levels. Depth recording of the monkey indicate that the early evoked potential originates in the region of dorsal column nuclei, while the later components are secondary to generators in cerebral cortex.

  11. Sex-Specific Automatic Responses to Infant Cries: TMS Reveals Greater Excitability in Females than Males in Motor Evoked Potentials

    PubMed Central

    Messina, Irene; Cattaneo, Luigi; Venuti, Paola; de Pisapia, Nicola; Serra, Mauro; Esposito, Gianluca; Rigo, Paola; Farneti, Alessandra; Bornstein, Marc H.

    2016-01-01

    Neuroimaging reveals that infant cries activate parts of the premotor cortical system. To validate this effect in a more direct way, we used event-related transcranial magnetic stimulation (TMS). Here, we investigated the presence and the time course of modulation of motor cortex excitability in young adults who listened to infant cries. Specifically, we recorded motor evoked potentials (MEPs) from the biceps brachii (BB) and interosseus dorsalis primus (ID1) muscles as produced by TMS delivered from 0 to 250 ms after sound onset in six steps of 50 ms in 10 females and 10 males. We observed an excitatory modulation of MEPs at 100 ms from the onset of infant cry specific to females and to the ID1 muscle. We regard this modulation as a response to natural cry sounds because it was attenuated to stimuli increasingly different from natural cry and absent in a separate group of females who listened to non-cry stimuli physically matched to natural infant cries. Furthermore, the 100-ms latency of this response is not compatible with a voluntary reaction to the stimulus but suggests an automatic, bottom-up audiomotor association. The brains of adult females appear to be tuned to respond to infant cries with automatic motor excitation. PMID:26779061

  12. Loss of somatosensory evoked potentials during intramedullary spinal cord surgery predicts postoperative neurologic deficits in motor function [corrected].

    PubMed

    Kearse, L A; Lopez-Bresnahan, M; McPeck, K; Tambe, V

    1993-01-01

    To estimate the sensitivity and specificity of somatosensory evoked potentials (SSEPs) for predicting new postoperative motor neurologic deficits during intramedullary spinal cord surgery; to establish whether SSEPs more accurately predicted postoperative deficits in position and vibration sense than in strength. Prospective open and retrospective study. University-affiliated hospital. 20 patients with intramedullary spinal cord tumors scheduled for surgery with intraoperative SSEPs. Median, ulnar, and tibial nerve cortical and subcortical SSEPs were recorded continuously. Conventional intraoperative SSEP criteria considered indicative of neurologic injury were modified and defined as either the complete and permanent loss of the SSEP or the simultaneous amplitude reduction of 50% or greater in the nearest recording electrode rostral to the surgical site and 0.5 millisecond increase in the central latency. Our definition required confirmation of both amplitude and latency changes on a repeated average. All patients had 1 or more SSEPs, which were reproducible and sufficiently stable for analysis throughout the operation. Six patients developed new postoperative neurologic deficits. One had new motor deficits in an extremity from which no baseline SSEPs could be elicited. In each of the other 5 patients, significant SSEP changes preceded the postoperative motor deficits in the extremity or extremities monitored. In no patient without a new postoperative motor deficit was there a significant change in the SSEP. In only 2 of these 5 patients was there a documented postoperative loss or diminution in vibration or position sense. Intraoperative SSEP changes during intramedullary spinal cord surgery are a sensitive predictor of new postoperative motor deficits, but such changes may not correlate reliably with postoperative deficits in position or vibration sense. In this setting SSEP monitoring serves primarily to reassure the operating team that, when the SSEPs remain

  13. Modulation of short- and long-interval intracortical inhibition with increasing motor evoked potential amplitude in a human hand muscle.

    PubMed

    Opie, George M; Semmler, John G

    2014-07-01

    The aim of the current study was to investigate the effect of increasing test motor evoked potential (MEP) amplitude on short- (SICI) and long-interval intracortical inhibition (LICI) at rest and during activation of the first dorsal interosseous (FDI) muscle. In 22 young subjects, a conditioning-test transcranial magnetic stimulation (TMS) paradigm was used to assess SICI and LICI at 5 different test TMS intensities (110-150% motor threshold) in resting and active FDI. In 9 additional subjects, SICI and LICI data were quantified when the test MEP amplitude represented specific proportions of the maximal compound muscle action potential (Mmax) in each subject. Test TMS intensity influenced SICI and LICI in rest and active FDI muscle. The normalised test MEP amplitude (%Mmax) did not influence SICI at rest, whereas there was a decrease in LICI at rest and an increase in SICI in active FDI with an increased normalised test MEP amplitude (%Mmax). Our results demonstrate differential effects of normalised test MEP amplitude (%Mmax) on SICI and LICI in resting and active FDI muscle. Estimation of SICI and LICI under some circumstances may be influenced by the normalised test MEP amplitude in subject populations with different Mmax characteristics. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  14. Effects of ketamine and propofol on motor evoked potentials elicited by intracranial microstimulation during deep brain stimulation

    PubMed Central

    Furmaga, Havan; Park, Hyun-Joo; Cooperrider, Jessica; Baker, Kenneth B.; Johnson, Matthew; Gale, John T.; Machado, Andre G.

    2014-01-01

    Few preclinical or clinical studies have evaluated the effect of anesthetics on motor evoked potentials (MEPs), either alone or in the presence of conditioning stimuli such as deep brain stimulation (DBS). In this study we evaluated the effects of two commonly used anesthetic agents, propofol and ketamine (KET), on MEPs elicited by intra-cortical microstimulation of the motor cortex in a rodent model with and without DBS of the dentatothalamocortical (DTC) pathway. The effects of propofol anesthesia on MEP amplitudes during DTC DBS were found to be highly dose dependent. Standard, but not high, dose propofol potentiated the facilitatory effects of 30 Hz DTC DBS on MEPs. This facilitation was sustained and phase-dependent indicating that, compared to high dose propofol, standard dose propofol has a beta-band excitatory effect on cortical networks. In contrast, KET anesthetic demonstrated a monotonic relationship with increasing frequencies of stimulation, such that the highest frequency of stimulation resulted in the greatest MEP amplitude. KET also showed phase dependency but less pronounced than standard dose propofol. The results underscore the importance of better understanding the complex effects of anesthetics on cortical networks and exogenous stimuli. Choice of anesthetic agents and dosing may significantly confound or even skew research outcomes, including experimentation in novel DBS indications and paradigms. PMID:24904312

  15. Motor-evoked potential gain is a helpful test for the detection of corticospinal tract dysfunction in amyotrophic lateral sclerosis.

    PubMed

    Duclos, Y; Grapperon, A M; Jouve, E; Truillet, R; Zemmour, C; Verschueren, A; Pouget, J; Attarian, S

    2017-02-01

    The detection of upper motor neuron (UMN) dysfunction is necessary for the diagnosis of amyotrophic lateral sclerosis (ALS). However, signs of UMN dysfunction may be difficult to establish. This study aimed to determine whether motor-evoked potential (MEP) gain (MEP area/background electromyographic activity) represents an efficient alternative to assess UMN dysfunction. MEP area, MEP/compound muscle action potential (CMAP) area ratio, and MEP gain were tested at different force levels in healthy control subjects and ALS patients. Receiver operating characteristic (ROC) curve analyses was used to determine the diagnostic utility of MEP gain and compare it to alternative techniques, namely, diffusion tensor imaging (DTI) and the triple stimulation technique (TST). MEP gain revealed a significant difference between the patients and healthy control subjects in contrast to MEP area and MEP/CMAP area ratio. The diagnostic utility of MEP gain was comparable with that of TST and superior to that of DTI. MEP gain can distinguish ALS patients from control subjects and may be helpful for the diagnosis of ALS. MEP gain appears to be a useful adjunct test and noninvasive method for the assessment of corticospinal dysfunction. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  16. Prolonged activity evokes potentiation and the "sag" phenomenon in slow motor units of rat soleus.

    PubMed

    Drzymała-Celichowska, Hanna; Raikova, Rositsa; Krutki, Piotr

    2016-01-01

    Slow motor units (MUs) have no sag in their unfused tetani. This study in anesthetized rats shows that the sag can be observed in slow soleus MUs after prolonged activity. Twitches and unfused tetanic contractions were recorded from male (n=35) and female (n=39) MUs before and after the four minutes of the fatigue test (trains of 13 pulses at 40 Hz repeated every second). After this activity twitch contractions potentiated and a shift in the steep part of the force-frequency curve towards lower frequencies was observed in both sexes. Initially no sag was visible in unfused tetani, but after the fatigue test the phenomenon was observed in 77% of male, while in 13% of female MUs, the result consistent with the previously reported higher content of IIa myosin and faster contraction of MUs in male soleus. The decomposition of tetani with sag into trains of twitch-shape responses to consecutive stimuli revealed higher forces of initial decomposed twitches than later. The revealed alterations the force development due to long-lasting activation of slow MUs were sex-related and more pronounced in male soleus.

  17. Dissociation of the pathways mediating ipsilateral and contralateral motor-evoked potentials in human hand and arm muscles

    PubMed Central

    Ziemann, Ulf; Ishii, Kenji; Borgheresi, Alessandra; Yaseen, Zaneb; Battaglia, Fortunato; Hallett, Mark; Cincotta, Massimo; Wassermann, Eric M

    1999-01-01

    Growing evidence points toward involvement of the human motor cortex in the control of the ipsilateral hand. We used focal transcranial magnetic stimulation (TMS) to examine the pathways of these ipsilateral motor effects.Ipsilateral motor-evoked potentials (MEPs) were obtained in hand and arm muscles of all 10 healthy adult subjects tested. They occurred in the finger and wrist extensors and the biceps, but no response or inhibitory responses were observed in the opponens pollicis, finger and wrist flexors and the triceps.The production of ipsilateral MEPs required contraction of the target muscle. The threshold TMS intensity for ipsilateral MEPs was on average 1.8 times higher, and the onset was 5.7 ms later (in the wrist extensor muscles) compared with size-matched contralateral MEPs.The corticofugal pathways of ipsilateral and contralateral MEPs could be dissociated through differences in cortical map location and preferred stimulating current direction.Both ipsi- and contralateral MEPs in the wrist extensors increased with lateral head rotation toward, and decreased with head rotation away from, the side of the TMS, suggesting a privileged input of the asymmetrical tonic neck reflex to the pathway of the ipsilateral MEP.Large ipsilateral MEPs were obtained in a patient with complete agenesis of the corpus callosum.The dissociation of the pathways for ipsilateral and contralateral MEPs indicates that corticofugal motor fibres other than the fast-conducting crossed corticomotoneuronal system can be activated by TMS. Our data suggest an ipsilateral oligosynaptic pathway, such as a corticoreticulospinal or a corticopropriospinal projection as the route for the ipsilateral MEP. Other pathways, such as branching of corticomotoneuronal axons, a transcallosal projection or a slow-conducting monosynaptic ipsilateral pathway are very unlikely or can be excluded. PMID:10420023

  18. Differences in Motor Evoked Potentials Induced in Rats by Transcranial Magnetic Stimulation under Two Separate Anesthetics: Implications for Plasticity Studies

    PubMed Central

    Sykes, Matthew; Matheson, Natalie A.; Brownjohn, Philip W.; Tang, Alexander D.; Rodger, Jennifer; Shemmell, Jonathan B. H.; Reynolds, John N. J.

    2016-01-01

    Repetitive transcranial magnetic stimulation (rTMS) is primarily used in humans to change the state of corticospinal excitability. To assess the efficacy of different rTMS stimulation protocols, motor evoked potentials (MEPs) are used as a readout due to their non-invasive nature. Stimulation of the motor cortex produces a response in a targeted muscle, and the amplitude of this twitch provides an indirect measure of the current state of the cortex. When applied to the motor cortex, rTMS can alter MEP amplitude, however, results are variable between participants and across studies. In addition, the mechanisms underlying any change and its locus are poorly understood. In order to better understand these effects, MEPs have been investigated in vivo in animal models, primarily in rats. One major difference in protocols between rats and humans is the use of general anesthesia in animal experiments. Anesthetics are known to affect plasticity-like mechanisms and so may contaminate the effects of an rTMS protocol. In the present study, we explored the effect of anesthetic on MEP amplitude, recorded before and after intermittent theta burst stimulation (iTBS), a patterned rTMS protocol with reported facilitatory effects. MEPs were assessed in the brachioradialis muscle of the upper forelimb under two anesthetics: a xylazine/zoletil combination and urethane. We found MEPs could be induced under both anesthetics, with no differences in the resting motor threshold or the average baseline amplitudes. However, MEPs were highly variable between animals under both anesthetics, with the xylazine/zoletil combination showing higher variability and most prominently a rise in amplitude across the baseline recording period. Interestingly, application of iTBS did not facilitate MEP amplitude under either anesthetic condition. Although it is important to underpin human application of TMS with mechanistic examination of effects in animals, caution must be taken when selecting an

  19. Differences in Motor Evoked Potentials Induced in Rats by Transcranial Magnetic Stimulation under Two Separate Anesthetics: Implications for Plasticity Studies.

    PubMed

    Sykes, Matthew; Matheson, Natalie A; Brownjohn, Philip W; Tang, Alexander D; Rodger, Jennifer; Shemmell, Jonathan B H; Reynolds, John N J

    2016-01-01

    Repetitive transcranial magnetic stimulation (rTMS) is primarily used in humans to change the state of corticospinal excitability. To assess the efficacy of different rTMS stimulation protocols, motor evoked potentials (MEPs) are used as a readout due to their non-invasive nature. Stimulation of the motor cortex produces a response in a targeted muscle, and the amplitude of this twitch provides an indirect measure of the current state of the cortex. When applied to the motor cortex, rTMS can alter MEP amplitude, however, results are variable between participants and across studies. In addition, the mechanisms underlying any change and its locus are poorly understood. In order to better understand these effects, MEPs have been investigated in vivo in animal models, primarily in rats. One major difference in protocols between rats and humans is the use of general anesthesia in animal experiments. Anesthetics are known to affect plasticity-like mechanisms and so may contaminate the effects of an rTMS protocol. In the present study, we explored the effect of anesthetic on MEP amplitude, recorded before and after intermittent theta burst stimulation (iTBS), a patterned rTMS protocol with reported facilitatory effects. MEPs were assessed in the brachioradialis muscle of the upper forelimb under two anesthetics: a xylazine/zoletil combination and urethane. We found MEPs could be induced under both anesthetics, with no differences in the resting motor threshold or the average baseline amplitudes. However, MEPs were highly variable between animals under both anesthetics, with the xylazine/zoletil combination showing higher variability and most prominently a rise in amplitude across the baseline recording period. Interestingly, application of iTBS did not facilitate MEP amplitude under either anesthetic condition. Although it is important to underpin human application of TMS with mechanistic examination of effects in animals, caution must be taken when selecting an

  20. Ipsilesional motor-evoked potential absence in pediatric hemiparesis impacts tracking accuracy of the less affected hand.

    PubMed

    Cassidy, Jessica M; Carey, James R; Lu, Chiahao; Krach, Linda E; Feyma, Tim; Durfee, William K; Gillick, Bernadette T

    2015-12-01

    This study analyzed the relationship between electrophysiological responses to transcranial magnetic stimulation (TMS), finger tracking accuracy, and volume of neural substrate in children with congenital hemiparesis. Nineteen participants demonstrating an ipsilesional motor-evoked potential (MEP) were compared with eleven participants showing an absent ipsilesional MEP response. Comparisons of finger tracking accuracy from the affected and less affected hands and ipsilesional/contralesional (I/C) volume ratio for the primary motor cortex (M1) and posterior limb of internal capsule (PLIC) were done using two-sample t-tests. Participants showing an ipsilesional MEP response demonstrated superior tracking performance from the less affected hand (p=0.016) and significantly higher I/C volume ratios for M1 (p=0.028) and PLIC (p=0.005) compared to participants without an ipsilesional MEP response. Group differences in finger tracking accuracy from the affected hand were not significant. These results highlight differentiating factors amongst children with congenital hemiparesis showing contrasting MEP responses: less affected hand performance and preserved M1 and PLIC volume. Along with MEP status, these factors pose important clinical implications in pediatric stroke rehabilitation. These findings may also reflect competitive developmental processes associated with the preservation of affected hand function at the expense of some function in the less affected hand. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Ipsilesional Motor-Evoked Potential Absence in Pediatric Hemiparesis Impacts Tracking Accuracy of the Less Affected Hand

    PubMed Central

    Cassidy, Jessica M.; Carey, James R.; Lu, Chiahao; Krach, Linda E.; Feyma, Tim; Durfee, William K.; Gillick, Bernadette T.

    2015-01-01

    This study analyzed the relationship between electrophysiological responses to transcranial magnetic stimulation (TMS), finger tracking accuracy, and volume of neural substrate in children with congenital hemiparesis. Nineteen participants demonstrating an ipsilesional motor-evoked potential (MEP) were compared with eleven participants showing an absent ipsilesional MEP response. Comparisons of finger tracking accuracy from the affected and less affected hands and ipsilesional/contralesional (I/C) volume ratio for the primary motor cortex (M1) and posterior limb of internal capsule (PLIC) were done using two-sample t-tests. Participants showing an ipsilesional MEP response demonstrated superior tracking performance from the less affected hand (p = 0.016) and significantly higher I/C volume ratios for M1 (p= 0.028) and PLIC (p = 0.005) compared to participants without an ipsilesional MEP response. Group differences in finger tracking accuracy from the affected hand were not significant. These results highlight differentiating factors amongst children with congenital hemiparesis showing contrasting MEP responses: less affected hand performance and preserved M1 and PLIC volume. Along with MEP status, these factors pose important clinical implications in pediatric stroke rehabilitation. These findings may also reflect competitive developmental processes associated with the preservation of affected hand function at the expense of some function in the less affected hand. PMID:26426515

  2. Effect of dexmedetomidine-etomidate-fentanyl combined anesthesia on somatosensory- and motor-evoked potentials in patients undergoing spinal surgery.

    PubMed

    Lin, Sheng; Dai, Na; Cheng, Zhengyan; Shao, Wei; Fu, Zhijian

    2014-05-01

    This aim of the present study was to evaluate the effects of dexmedetomidine (DEX) on the intraoperative monitoring of somatosensory-evoked potentials (SEPs) and motor-evoked potentials (MEPs) in patients undergoing spinal surgery. A total of 36 patients who received spinal surgery under general anesthesia were randomly divided into two groups (n=18 per group), group C, the test group and group D, the control group, and these groups were subjected to a matching anesthesia induction. In brief, the anesthesia was administered via injection of etomidate and fentanyl; once the patients were unconscious, a laryngeal mask airway (LMA) was inserted, SEPs and MEPs were monitored and the collected data were considered to be basic data. Cisatracurium was subsequently injected and an endotracheal tube (7#) was inserted to replace the LMA. The following procedures were conducted for anesthesia maintenance: Group C, the anesthesia was maintained via target-controlled infusion of etomidate and intermittent injection of fentanyl; and group D, DEX (0.5 μg/kg) was injected over a duration of 10 min and then pumped at a rate of 0.5 μg/kg/h. In the two groups, all of the other drugs used were the same and a muscle relaxant was not administered. The bispectral index was maintained between 45 and 55 during surgery, and the SEPs and MEPs were monitored continuously until the surgery was completed. No significant difference in duration and amplitude of the SEPs (P15-N20) was identified between group C and D (P>0.05). Furthermore, the MEPs were monitored in the two groups at specific durations and no significant difference was observed between the two groups (P>0.05). The SEPs and MEPs were maintained in the patients who were administered with the DEX-etomidate-fentanyl combined anesthesia during spinal surgery.

  3. Evoked Potential Studies of the Effects of Impact Acceleration on the Motor Nervous System,

    DTIC Science & Technology

    1983-01-01

    Thomas 2 , M.S. Weiss 2 , M.D. Berger , A. Sances Jr. P.R Wls ,JMyklebust ~, S.J. Larson, E~. Js "Texas Research Institute of Mental Sciences...the measurement of alter- a five-in-line lead parallel array placed over ations in neural transmission along the motor the spinal cord. Recording

  4. N30 Somatosensory Evoked Potential Is Negatively Correlated with Motor Function in Parkinson’s Disease

    PubMed Central

    Kang, Suk Yun; Ma, Hyeo-Il

    2016-01-01

    Objective The aim of this study was to investigate frontal N30 status in Parkinson’s disease (PD) and to examine the correlation between the amplitude of frontal N30 and the severity of motor deficits. Methods The frontal N30 was compared between 17 PD patients and 18 healthy volunteers. Correlations between the amplitude of frontal N30 and the Unified Parkinson’s Disease Rating Scale (UPDRS) motor score of the more severely affected side was examined. Results The mean latency of the N30 was not significantly different between patients and healthy volunteers (p = 0.981), but the mean amplitude was lower in PD patients (p < 0.025). There was a significant negative correlation between the amplitude of N30 and the UPDRS motor score (r = -0.715, p = 0.013). Conclusions The frontal N30 status indicates the motor severity of PD. It can be a useful biomarker reflecting dopaminergic deficits and an objective measurement for monitoring the clinical severity of PD. PMID:26828214

  5. Does navigated transcranial stimulation increase the accuracy of tractography? A prospective clinical trial based on intraoperative motor evoked potential monitoring during deep brain stimulation.

    PubMed

    Forster, Marie-Therese; Hoecker, Alexander Claudius; Kang, Jun-Suk; Quick, Johanna; Seifert, Volker; Hattingen, Elke; Hilker, Rüdiger; Weise, Lutz Martin

    2015-06-01

    Tractography based on diffusion tensor imaging has become a popular tool for delineating white matter tracts for neurosurgical procedures. To explore whether navigated transcranial magnetic stimulation (nTMS) might increase the accuracy of fiber tracking. Tractography was performed according to both anatomic delineation of the motor cortex (n = 14) and nTMS results (n = 9). After implantation of the definitive electrode, stimulation via the electrode was performed, defining a stimulation threshold for eliciting motor evoked potentials recorded during deep brain stimulation surgery. Others have shown that of arm and leg muscles. This threshold was correlated with the shortest distance between the active electrode contact and both fiber tracks. Results were evaluated by correlation to motor evoked potential monitoring during deep brain stimulation, a surgical procedure causing hardly any brain shift. Distances to fiber tracks clearly correlated with motor evoked potential thresholds. Tracks based on nTMS had a higher predictive value than tracks based on anatomic motor cortex definition (P < .001 and P = .005, respectively). However, target site, hemisphere, and active electrode contact did not influence this correlation. The implementation of tractography based on nTMS increases the accuracy of fiber tracking. Moreover, this combination of methods has the potential to become a supplemental tool for guiding electrode implantation.

  6. Time-varying coupling of EEG oscillations predicts excitability fluctuations in the primary motor cortex as reflected by motor evoked potentials amplitude: an EEG-TMS study.

    PubMed

    Ferreri, Florinda; Vecchio, Fabrizio; Ponzo, David; Pasqualetti, Patrizio; Rossini, Paolo Maria

    2014-05-01

    Motor evoked potentials (MEPs) elicited by a train of consecutive, individual transcranial magnetic stimuli demonstrate fluctuations in amplitude with respect to time when recorded from a relaxed muscle. The influence of time-varying, instantaneous modifications of the electroencephalography (EEG) properties immediately preceding the transcranial magnetic stimulation (TMS) has rarely been explored. The aim of this study was to investigate the influence of the pre-TMS motor cortex and related areas EEG profile on time variants of the MEPs amplitude. MRI-navigated TMS and multichannel TMS-compatible EEG devices were used. For each experimental subject, post-hoc analysis of the MEPs amplitude that was based on the 50th percentile of the MEPs amplitude distribution provided two subgroups corresponding to "high" (large amplitude) and "low" (small amplitude). The pre-stimulus EEG characteristics (coherence and spectral profile) from the motor cortex and related areas were analyzed separately for the "high" and "low" MEPs and were then compared. On the stimulated hemisphere, EEG coupling was observed more often in the high compared to the low MEP trials. Moreover, a paradigmatic pattern in which TMS was able to lead to significantly larger MEPs was found when the EEG of the stimulated motor cortex was coupled in the beta 2 band with the ipsilateral prefrontal cortex and in the delta band with the bilateral centro-parietal-occipital cortices. This data provide evidence for a statistically significant influence of time-varying and spatially patterned synchronization of EEG rhythms in determining cortical excitability, namely motor cortex excitability in response to TMS. Copyright © 2013 Wiley Periodicals, Inc.

  7. Motor-Evoked Potentials in the Lower Back Are Modulated by Visual Perception of Lifted Weight

    PubMed Central

    Behrendt, Frank; de Lussanet, Marc H. E.; Zentgraf, Karen; Zschorlich, Volker R.

    2016-01-01

    Facilitation of the primary motor cortex (M1) during the mere observation of an action is highly congruent with the observed action itself. This congruency comprises several features of the executed action such as somatotopy and temporal coding. Studies using reach-grasp-lift paradigms showed that the muscle-specific facilitation of the observer’s motor system reflects the degree of grip force exerted in an observed hand action. The weight judgment of a lifted object during action observation is an easy task which is the case for hand actions as well as for lifting boxes from the ground. Here we investigated whether the cortical representation in M1 for lumbar back muscles is modulated due to the observation of a whole-body lifting movement as it was shown for hand action. We used transcranial magnetic stimulation (TMS) to measure the corticospinal excitability of the m. erector spinae (ES) while subjects visually observed the recorded sequences of a person lifting boxes of different weights from the floor. Consistent with the results regarding hand action the present study reveals a differential modulation of corticospinal excitability despite the relatively small M1 representation of the back also for lifting actions that mainly involve the lower back musculature. PMID:27336751

  8. Motor-Evoked Potentials in the Lower Back Are Modulated by Visual Perception of Lifted Weight.

    PubMed

    Behrendt, Frank; de Lussanet, Marc H E; Zentgraf, Karen; Zschorlich, Volker R

    2016-01-01

    Facilitation of the primary motor cortex (M1) during the mere observation of an action is highly congruent with the observed action itself. This congruency comprises several features of the executed action such as somatotopy and temporal coding. Studies using reach-grasp-lift paradigms showed that the muscle-specific facilitation of the observer's motor system reflects the degree of grip force exerted in an observed hand action. The weight judgment of a lifted object during action observation is an easy task which is the case for hand actions as well as for lifting boxes from the ground. Here we investigated whether the cortical representation in M1 for lumbar back muscles is modulated due to the observation of a whole-body lifting movement as it was shown for hand action. We used transcranial magnetic stimulation (TMS) to measure the corticospinal excitability of the m. erector spinae (ES) while subjects visually observed the recorded sequences of a person lifting boxes of different weights from the floor. Consistent with the results regarding hand action the present study reveals a differential modulation of corticospinal excitability despite the relatively small M1 representation of the back also for lifting actions that mainly involve the lower back musculature.

  9. Motor-evoked potentials in masseter muscle by electrical and magnetic stimulation in intact alert man.

    PubMed

    Macaluso, G M; Pavesi, G; Bonanini, M; Mancia, D; Gennari, P U

    1990-01-01

    The electromyographic responses of the masseter after different types of transcranial stimulation were recorded with surface and needle electrodes. Magnetic stimulation at 4 cm lateral to the vertex on the biauricular line elicited MEPs in the contralateral masseter (latency 6.9 ms) due to activation of motor cortex or adjacent elements along the cortico-nuclear pathway. The ipsilateral responses to the same stimuli and to more lateral ones had shorter latencies and were ascribed to direct stimulation of the trigeminal nerve, probably its intracisternal portion. This was also the probable origin of the ipsilateral MEPs after both anodic and cathodic bipolar electrical stimulation at 7 and 11 cm lateral to the vertex on the biauricular line.

  10. A comparison of the effects of desflurane versus propofol on transcranial motor-evoked potentials in pediatric patients.

    PubMed

    Holdefer, Robert N; Anderson, Corrie; Furman, Michele; Sangare, Yoro; Slimp, Jefferson C

    2014-12-01

    The aim was to compare the effects of propofol and desflurane anesthesia on transcranial motor evoked potentials (MEPs) from pediatric patients undergoing surgery for spinal deformities. Desflurane and propofol cohorts (25 patients each) were obtained retrospectively and matched for patient characteristics and surgical approach. MEPs from the thenar eminence and abductor hallucis were compared during maintenance anesthesia on desflurane (0.6-0.8 MAC) or propofol infusion (150-300 μg/kg/min). MEP amplitudes and durations were obtained for successive 30-min intervals for 150 min, beginning 60 min after maintenance anesthesia. Mean peak to peak amplitudes of MEPs under desflurane anesthesia from the thenar eminence (419 μV) and abductor hallucis (386 μv) were not significantly different from those under propofol (608 μV, 343 μV, thenar, and abductor hallucis, respectively). Stimulation was greater by 42 V and 136 mA, and trains were slightly longer in the desflurane compared to the propofol group (p < 0.05). Most MEP amplitudes for the desflurane and propofol cohorts remained the same or increased (71 % of cases) when those after 150 min were compared to those in the first 30-min interval. MEPs with good amplitudes were obtained under desflurane only anesthesia that were comparable to propofol only anesthesia in pediatric patients during surgery for spinal deformities. There was no evidence for anesthetic fade over the time period examined. When used by itself, desflurane can be considered a viable alternative to propofol anesthesia.

  11. Test-retest reliability of motor evoked potentials (MEPs) at the submental muscle group during volitional swallowing.

    PubMed

    Doeltgen, Sebastian H; Ridding, Michael C; O'Beirne, Greg A; Dalrymple-Alford, John; Huckabee, Maggie-Lee

    2009-03-30

    Motor evoked potentials (MEPs) recorded from pharyngeal and anterior hyo-mandibular (submental) muscles at rest have been used to evaluate treatment effects on neural pathways underlying swallowing. This study documents a novel methodological approach of recording reliable intra- and inter-session MEPs at the submental muscle group during task-related volitional swallowing. MEPs were elicited by single-pulse transcranial magnetic stimulation (TMS), triggered by a custom-made system when a pre-set level of surface electromyographic activity in the target muscles was breached. Fifteen MEPs were recorded during each of four sessions. Intraclass correlation coefficients (ICCs) were used to assess test-retest reliability within and across sessions for blocks of 3, 5, 10 and 15 trials. Highly reliable intra-session reliability was achieved, maximal for blocks of five trials (0.915). Inter-session reliability varied between 0.474 (three trials per block) and 0.909 (10 trials per block). Surface electromyography-triggered TMS allows reliable measurement of MEP amplitude at the submental muscle group within and across sessions when muscles are pre-activated during volitional swallowing. This methodology will be useful for future investigations on the effects of pathology and modulation of swallowing neural pathways.

  12. Evoked Potential Variability

    PubMed Central

    Hu, Lingli; Boutros, Nash N.; Jansen, Ben H.

    2008-01-01

    An unsupervised correlation-based clustering method was developed to assess the trial-to-trial variability of auditory evoked potentials (AEPs). The method first decomposes single trials into three frequency bands, each containing activity primarily associated with one of the three major AEP components, i.e., P50, N100 and P200. Next, single-trial evoked potentials with similar post-stimulus characteristics are clustered and selectively averaged to determine the presence or absence of an AEP component. The method was evaluated on actual AEP and spontaneous EEG data collected from 25 healthy participants using a paradigm in which pairs of identical tones were presented, with the first stimulus (S1) presented 0.5 s before the second stimulus (S2). Homogeneous, well-separated clusters were obtained and substantial AEP variability was found. Also, there was a trend for S2 to produce fewer ‘complete’ (and significantly smaller) responses than S1. Tests conducted on spontaneous EEG produced similar clusters as obtained from EP data, but significantly fewer stimuli produced responses containing all three EP components than seen in AEP data. These findings suggest that the clustering method presented here performs adequately to assess trial-to-trial EP variability. Also, the results suggest that the sensory gating observed in normal controls may be caused by the fact that the second stimulus generates fewer ‘responsive’ trials than the first stimulus, thus resulting in smaller ensemble averages. PMID:19103222

  13. Somatosensory and motor evoked potentials as biomarkers for post-operative neurological status.

    PubMed

    Holdefer, R N; MacDonald, D B; Skinner, S A

    2015-05-01

    SEPs and MEPs (EPs) are often used as surrogates for postoperative clinical endpoints of muscle strength and sensory status, as these true endpoints are not available during surgery. EPs as surrogate endpoints were evaluated using a three step framework (Analytical Validation, Qualification, Utilization) recently proposed by the Institute of Medicine (USA). EP performance on Analytical Validation may surpass that of some other biomarkers used in medicine (tumor size, cardiac troponin). Qualification of EP surrogates was evaluated with guidelines for causation proposed by A.B. Hill, which supported causal links between surgical events and EP changes and revised estimates of EP diagnostic test performance for three illustrative studies. Qualification was also addressed with a 3×2 contingency analysis which demonstrated decreased deficit proportions for EP declines which recovered after surgeon intervention. Utilization of EP surrogates will depend on surgical procedure and alert criteria. EPs are often used as surrogate endpoints to avoid new postoperative deficits. Although not fully validated, their continued use as surrogates during surgical procedures with the potential for significant morbidity is justified by their potential to help avoid injury and the absence of "second best options." Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  14. Does transcranial stimulation for motor evoked potentials (TcMEP) worsen seizures in epileptic patients following spinal deformity surgery?

    PubMed

    Salem, Khalid M I; Goodger, Laura; Bowyer, Katherine; Shafafy, Masood; Grevitt, Michael P

    2016-10-01

    To investigate the effect of Transcranial Motor Evoked Potentials (TcMEP) in increasing the severity or frequency of post-operative seizures in patients undergoing deformity corrective spine surgery with a known history of seizures pre-operatively. The information on all patients with history of epilepsy/seizures who underwent spinal TcMEP cord monitoring for deformity correction surgery was retrospectively collected through a review of the hospital notes. The benefits of TcMEP in the early detection of potential cord ischemia were deemed by the operating surgeon to outweigh the increased risks of seizures, tongue biting, etc. Data on age, gender, pre-operative diagnosis, curve type, intra-operative monitoring alerts, duration of hospital stay, and post-operative in-hospital seizures were collected. Additionally, the patients were contacted following discharge and data on any change in the frequency of the seizures or an alteration in seizure-related medication post-operatively was also collected. The records of 449 consecutively monitored patients were reviewed and 12 (2.7 %) patients with a history of seizures pre-operatively were identified. The mean age was 23 (9-59) years, 7 females, 11 scoliosis corrections (4 neuromuscular, 1 degenerative, 6 idiopathic adolescent), and one sagittal balance correction surgery. Intra-operatively, all patients had TcMEP monitoring, were catheterised, and had no neuromonitoring alerts or record of tongue biting or laceration. Post-operatively, the mean hospital stay was 12 (4-25) days with no recorded seizures. At a mean of 23 (12-49) months post-discharge, none of the patients reported a worsening of seizures (pattern or frequency) or required an alteration in the seizure-related medications. TcMEP does not appear to trigger intra-operative or post-operative seizures and is not associated with deterioration in the seizure control of patients suffering seizures pre-operatively.

  15. Effects of high-frequency repetitive transcranial magnetic stimulation of primary motor cortex on laser-evoked potentials in migraine.

    PubMed

    de Tommaso, Marina; Brighina, Filippo; Fierro, Brigida; Francesco, Vito Devito; Santostasi, Roberto; Sciruicchio, Vittorio; Vecchio, Eleonora; Serpino, Claudia; Lamberti, Paolo; Livrea, Paolo

    2010-12-01

    The aim of this study was to examine the effects of high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS) of the left primary motor cortex (M1) on subjective pain and evoked responses induced by laser stimulation (LEPs) of the contralateral hand and supraorbital zone in a cohort of migraine patients without aura during the inter-critical phase, and to compare the effects with those of non-migraine healthy controls. Thirteen migraine patients and 12 sex- and age-matched controls were evaluated. Each rTMS session consisted of 1,800 stimuli at a frequency of 5 Hz and 90% motor threshold intensity. Sham (control) rTMS was performed at the same stimulation position. The vertex LEP amplitude was reduced at the trigeminal and hand levels in the sham-placebo condition and after rTMS to a greater extent in the migraine patients than in healthy controls, while the laser pain rating was unaffected. These results suggest that HF rTMS of motor cortex and the sham procedure can both modulate pain-related evoked responses in migraine patients.

  16. The Predictive Value of Motor-Evoked Potentials and the Silent Period on Patient Outcome after Acute Cerebral Infarction.

    PubMed

    Zhang, Xueqing; Ji, Wenzhen; Li, Lancui; Yu, Changshen; Wang, Wanjun; Liu, Shoufeng; Gao, Chunlin; Qiu, Lina; Tong, Xiaoguang; Wang, Jinhuan; Wu, Jialing

    2016-07-01

    The predictive value of neurophysiologic assessment on patients' outcome after acute cerebral infarction is poorly understood. The aim of this study was to investigate the prognostic value of motor-evoked potentials (MEPs) and the silent period (SP) on clinical outcome. A total of 202 patients with acute cerebral infarction were prospectively recruited. MEP and SP were recorded from the abductor pollicis brevis of the affected side within 10 days after stroke onset. Patient outcome was measured as the dependency rate. Cortical MEP was induced in 78 patients whereas it was absent in 82 patients. The initial NIHSS (National Institutes of Health Stroke Scale) score was significantly lower in patients with MEP than in those without MEP (P < .001). Regression analysis demonstrated that a left-sided lesion (OR = .391, 95% CI .178-.858, P = .019), NIHSS at admission (OR = .826, 95% CI .744-.917, P < .001), and presence of MEP (OR = 3.918, 95% CI 1.770-8.672, P < .001) were independent predictors of outcome 3 months after stroke. Among patients with MEP, only the contralateral cortical SP value was significantly shorter in the good outcome subgroup (t = 2.541, P = .013). Receiver operating characteristic curve analysis demonstrated that SP was able to predict patients at higher risk of unfavorable outcome 3 months after stroke onset (area under the curve .721, 95% CI .58-.86, P = .008). These data suggested that MEP and SP were useful tools to predict patients' acute outcomes following cerebral infarction. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  17. Comparative Sensitivity of Intraoperative Motor Evoked Potential Monitoring in Predicting Postoperative Neurologic Deficits: Nondegenerative versus Degenerative Myelopathy.

    PubMed

    Clark, Aaron J; Safaee, Michael; Chou, Dean; Weinstein, Philip R; Molinaro, Annette M; Clark, John P; Mummaneni, Praveen V

    2016-08-01

    Retrospective review. Intraoperative motor evoked potential (MEP) monitoring in spine surgery may assist surgeons in taking corrective measures to prevent neurologic deficits. The efficacy of monitoring MEPs intraoperatively in patients with myelopathy from nondegenerative causes has not been quantified. We compared the sensitivity and specificity of intraoperative MEP monitoring in patients with myelopathy caused by nondegenerative processes to patients with degenerative cervicothoracic spondylotic myelopathy (CSM). We retrospectively reviewed our myelopathy surgical cases during a 1-year period to identify patients with degenerative CSM and CSM of nondegenerative causes and collected data on intraoperative MEP changes and postoperative new deficits. Categorical variables were analyzed by Fisher exact test. Receiver operator curves assessed intraoperative MEP monitoring performance in the two groups. In all, 144 patients were identified: 102 had degenerative CSM and 42 had CSM of nondegenerative causes (24 extra-axial tumors, 12 infectious processes, 5 traumatic fractures, and 1 rheumatoid arthritis). For degenerative CSM, there were 11 intraoperative MEP alerts and 7 new deficits (p < 0.001). The corresponding sensitivity was 71% and the specificity was 94%. In the nondegenerative group, there were 11 intraoperative MEP alerts and 3 deficits, which was not significant (p > 0.99). The sensitivity (33%) and specificity (74%) were lower. Among patients with degenerative CSM, the model performed well for predicting postoperative deficits (area under the curve [AUC] 0.826), which appeared better than the nondegenerative group, although it did not reach statistical significance (AUC 0.538, p = 0.16). Based on this large retrospective analysis, intraoperative MEP monitoring in surgery for nondegenerative CSM cases appears to be less sensitive to cord injury and less predictive of postoperative deficits when compared with degenerative CSM cases.

  18. Assessment of intraoperative motor evoked potentials for predicting postoperative paraplegia in thoracic and thoracoabdominal aortic aneurysm repair.

    PubMed

    Horiuchi, Toshinori; Kawaguchi, Masahiko; Inoue, Satoki; Hayashi, Hironobu; Abe, Ryuichi; Tabayashi, Nobuoki; Taniguchi, Shigeki; Furuya, Hitoshi

    2011-02-01

    Monitoring motor evoked potentials (MEPs) has been recognized as a highly reliable method to detect intraoperative spinal cord ischemia (SCI) in aortic repair. However, the data regarding the sensitivity and specificity of MEPs for predicting postoperative paraplegia are limited. We retrospectively assessed the value of intraoperative MEP amplitudes for predicting postoperative paraplegia. The medical records of 44 patients were reviewed. A train-of-five stimulation was delivered to C3-C4, and MEPs were recorded from the abductor pollicis brevis and the tibialis anterior muscles. The cutoff point for detecting SCI was set at 75% decrease of the baseline MEP. Receiver operating characteristic curves were applied at various cutoff points. Three patients (6.8%) had postoperative paraplegia. The minimum MEP during surgery had 100% sensitivity and 64.9% specificity in predicting paraplegia, and the MEP at the end of surgery had 66.7% sensitivity and 78.0% specificity in predicting paraplegia: only 1 patient, who had borderline paraplegia (right monoparesis), showed a false-negative result. Receiver operating characteristic curves indicated that adequate cutoff points for the minimum MEP during surgery and for the MEP amplitude at the end of surgery were a 75-90% decrease and a 64-75% decrease of the baseline MEP, respectively. Monitoring MEPs had relatively high sensitivity and acceptable specificity, with the cutoff point set at 75% decrease of the baseline MEP, for predicting paraplegia and paraparesis. Because of the small sample in our study, further investigations would be necessary to investigate an adequate cutoff point that could predict postoperative paraplegia.

  19. Comparative Sensitivity of Intraoperative Motor Evoked Potential Monitoring in Predicting Postoperative Neurologic Deficits: Nondegenerative versus Degenerative Myelopathy

    PubMed Central

    Clark, Aaron J.; Safaee, Michael; Chou, Dean; Weinstein, Philip R.; Molinaro, Annette M.; Clark, John P.; Mummaneni, Praveen V.

    2015-01-01

    Study Design  Retrospective review. Objective  Intraoperative motor evoked potential (MEP) monitoring in spine surgery may assist surgeons in taking corrective measures to prevent neurologic deficits. The efficacy of monitoring MEPs intraoperatively in patients with myelopathy from nondegenerative causes has not been quantified. We compared the sensitivity and specificity of intraoperative MEP monitoring in patients with myelopathy caused by nondegenerative processes to patients with degenerative cervicothoracic spondylotic myelopathy (CSM). Methods  We retrospectively reviewed our myelopathy surgical cases during a 1-year period to identify patients with degenerative CSM and CSM of nondegenerative causes and collected data on intraoperative MEP changes and postoperative new deficits. Categorical variables were analyzed by Fisher exact test. Receiver operator curves assessed intraoperative MEP monitoring performance in the two groups. Results  In all, 144 patients were identified: 102 had degenerative CSM and 42 had CSM of nondegenerative causes (24 extra-axial tumors, 12 infectious processes, 5 traumatic fractures, and 1 rheumatoid arthritis). For degenerative CSM, there were 11 intraoperative MEP alerts and 7 new deficits (p < 0.001). The corresponding sensitivity was 71% and the specificity was 94%. In the nondegenerative group, there were 11 intraoperative MEP alerts and 3 deficits, which was not significant (p > 0.99). The sensitivity (33%) and specificity (74%) were lower. Among patients with degenerative CSM, the model performed well for predicting postoperative deficits (area under the curve [AUC] 0.826), which appeared better than the nondegenerative group, although it did not reach statistical significance (AUC 0.538, p = 0.16). Conclusions  Based on this large retrospective analysis, intraoperative MEP monitoring in surgery for nondegenerative CSM cases appears to be less sensitive to cord injury and less predictive of postoperative

  20. Incidence of intraoperative seizures during motor evoked potential monitoring in a large cohort of patients undergoing different surgical procedures.

    PubMed

    Ulkatan, Sedat; Jaramillo, Ana Maria; Téllez, Maria J; Kim, Jinu; Deletis, Vedran; Seidel, Kathleen

    2017-04-01

    OBJECTIVE The purpose of this study was to investigate the incidence of seizures during the intraoperative monitoring of motor evoked potentials (MEPs) elicited by electrical brain stimulation in a wide spectrum of surgeries such as those of the orthopedic spine, spinal cord, and peripheral nerves, interventional radiology procedures, and craniotomies for supra- and infratentorial tumors and vascular lesions. METHODS The authors retrospectively analyzed data from 4179 consecutive patients who underwent surgery or an interventional radiology procedure with MEP monitoring. RESULTS Of 4179 patients, only 32 (0.8%) had 1 or more intraoperative seizures. The incidence of seizures in cranial procedures, including craniotomies and interventional neuroradiology, was 1.8%. In craniotomies in which transcranial electrical stimulation (TES) was applied to elicit MEPs, the incidence of seizures was 0.7% (6/850). When direct cortical stimulation was additionally applied, the incidence of seizures increased to 5.4% (23/422). Patients undergoing craniotomies for the excision of extraaxial brain tumors, particularly meningiomas (15 patients), exhibited the highest risk of developing an intraoperative seizure (16 patients). The incidence of seizures in orthopedic spine surgeries was 0.2% (3/1664). None of the patients who underwent surgery for conditions of the spinal cord, neck, or peripheral nerves or who underwent cranial or noncranial interventional radiology procedures had intraoperative seizures elicited by TES during MEP monitoring. CONCLUSIONS In this largest such study to date, the authors report the incidence of intraoperative seizures in patients who underwent MEP monitoring during a wide spectrum of surgeries such as those of the orthopedic spine, spinal cord, and peripheral nerves, interventional radiology procedures, and craniotomies for supra- and infratentorial tumors and vascular lesions. The low incidence of seizures induced by electrical brain stimulation

  1. Diagnostic accuracy of motor evoked potentials to detect neurological deficit during idiopathic scoliosis correction: a systematic review.

    PubMed

    Thirumala, Parthasarathy D; Crammond, Donald J; Loke, Yoon K; Cheng, Hannah L; Huang, Jessie; Balzer, Jeffrey R

    2017-03-01

    OBJECTIVE The goal of this study was to evaluate the efficacy of intraoperative transcranial motor evoked potential (TcMEP) monitoring in predicting an impending neurological deficit during corrective spinal surgery for patients with idiopathic scoliosis (IS). METHODS The authors searched the PubMed and Web of Science database for relevant lists of retrieved reports and/or experiments published from January 1950 through October 2014 for studies on TcMEP monitoring use during IS surgery. The primary analysis of this review fit the operating characteristic into a hierarchical summary receiver operating characteristic curve model to determine the efficacy of intraoperative TcMEP-predicted change. RESULTS Twelve studies, with a total of 2102 patients with IS were included. Analysis found an observed incidence of neurological deficits of 1.38% (29/2102) in the sample population. Of the patients who sustained a neurological deficit, 82.8% (24/29) also had irreversible TcMEP change, whereas 17.2% (5/29) did not. The pooled analysis using the bivariate model showed TcMEP change with sensitivity (mean 91% [95% CI 34%-100%]) and specificity (mean 96% [95% CI 92-98%]). The diagnostic odds ratio indicated that it is 250 times more likely to observe significant TcMEP changes in patients who experience a new-onset motor deficit immediately after IS correction surgery (95% CI 11-5767). TcMEP monitoring showed high discriminant ability with an area under the curve of 0.98. CONCLUSIONS A patient with a new neurological deficit resulting from IS surgery was 250 times more likely to have changes in TcMEPs than a patient without new deficit. The authors' findings from 2102 operations in patients with IS show that TcMEP monitoring is a highly sensitive and specific test for detecting new spinal cord injuries in patients undergoing corrective spinal surgery for IS. They could not assess the value of TcMEP monitoring as a therapeutic adjunct owing to the limited data available and their

  2. The warning-sign hierarchy between quantitative subcortical motor mapping and continuous motor evoked potential monitoring during resection of supratentorial brain tumors.

    PubMed

    Seidel, Kathleen; Beck, Jürgen; Stieglitz, Lennart; Schucht, Philippe; Raabe, Andreas

    2013-02-01

    Mapping and monitoring are believed to provide an early warning sign to determine when to stop tumor removal to avoid mechanical damage to the corticospinal tract (CST). The objective of this study was to systematically compare subcortical monopolar stimulation thresholds (1-20 mA) with direct cortical stimulation (DCS)-motor evoked potential (MEP) monitoring signal abnormalities and to correlate both with new postoperative motor deficits. The authors sought to define a mapping threshold and DCS-MEP monitoring signal changes indicating a minimal safe distance from the CST. A consecutive cohort of 100 patients underwent tumor surgery adjacent to the CST while simultaneous subcortical motor mapping and DCS-MEP monitoring was used. Evaluation was done regarding the lowest subcortical mapping threshold (monopolar stimulation, train of 5 stimuli, interstimulus interval 4.0 msec, pulse duration 500 μsec) and signal changes in DCS-MEPs (same parameters, 4 contact strip electrode). Motor function was assessed 1 day after surgery, at discharge, and at 3 months postoperatively. The lowest individual motor thresholds (MTs) were as follows (MT in mA, number of patients): > 20 mA, n = 12; 11-20 mA, n = 13; 6-10 mA, n = 20; 4-5 mA, n = 30; and 1-3 mA, n = 25. Direct cortical stimulation showed stable signals in 70 patients, unspecific changes in 18, irreversible alterations in 8, and irreversible loss in 4 patients. At 3 months, 5 patients had a postoperative new or worsened motor deficit (lowest mapping MT 20 mA, 13 mA, 6 mA, 3 mA, and 1 mA). In all 5 patients DCS-MEP monitoring alterations were documented (2 sudden irreversible threshold increases and 3 sudden irreversible MEP losses). Of these 5 patients, 2 had vascular ischemic lesions (MT 20 mA, 13 mA) and 3 had mechanical CST damage (MT 1 mA, 3 mA, and 6 mA; in the latter 2 cases the resection continued after mapping and severe DCS-MEP alterations occurred thereafter). In 80% of patients with a mapping MT of 1-3 mA and in

  3. Patient characteristics and anesthetic technique are additive but not synergistic predictors of successful motor evoked potential monitoring.

    PubMed

    Deiner, Stacie G; Kwatra, Shawn G; Lin, Hung-Mo; Weisz, Donald J

    2010-08-01

    Spinal cord monitoring is associated with a significantly lower rate of neurologic deficits after deformity surgery, and has been shown to have predictive value in cervical, thoracic, and lumbar surgery. Lower extremity motor evoked potentials (MEPs) are particularly sensitive to anesthetics and physiologic change, and can be difficult to obtain at baseline. The anesthesiologist is often required to modify the maintenance anesthetic to facilitate signal attainment. Although intuitive, the predictive significance of increasing age, body mass index (BMI), presence of diabetes and/or hypertension, surgical procedure, and anesthetic technique has not been well delineated. We conducted a retrospective chart review of the anesthetic records of all patients who underwent spine surgery and MEP monitoring of the lower extremities from August 1, 2001 to December 31, 2005. Patients with preexisting paralysis of the lower extremities were excluded. Univariate analysis was performed to examine the distribution of diabetes, hypertension, anesthesia technique, age, gender, BMI, and surgical procedure. The chi(2) test and the 2-sample t test were used to test associations between MEP status and potential risk factors. Cochran-Armitage test was used to analyze trends in BMI and age by quartile. The effects of diabetes and hypertension, compared with patients with neither, were presented for each anesthetic technique. Bivariate analysis of the data was performed to analyze a potentially synergistic deleterious effect of diabetes, hypertension, and anesthetic technique using the Breslow-Day test for homogeneity of the odds ratios. Logistic regression analysis through stepwise selection was performed to form a model of the data. Two hundred fifty-six charts were reviewed. The univariate analysis showed that diabetes, hypertension, anesthesia technique, age, and BMI were significantly associated with failure to obtain MEP signals. None of the variables were found to have a synergistic

  4. Visual evoked potentials in neonatal hyperbilirubinemia.

    PubMed

    Chen, Wen-Xiong; Wong, Virginia

    2006-01-01

    The management of neonatal hyperbilirubinemia is very standardized. However, there is a lack of an objective method to evaluate the cerebral effects of bilirubin apart from brainstem auditory evoked potentials. There were few studies evaluating the effects of hyperbilirubinemia or phototherapy on the visual pathway in infants with hyperbilirubinemia. Serial visual evoked potentials of two groups of term neonates (N = 24)--group 1 with moderate hyperbilirubinemia (n = 16) and group 2 with severe hyperbilirubinemia (n = 8)--were evaluated prospectively. All infants had regular physical, neurologic, visual, and auditory evaluations until 3 years. Four (16%) had abnormal visual evoked potentials before 1 year, and the abnormalities returned to normal thereafter. There was no significant difference in visual evoked potentials between the two groups. All had normal neurodevelopmental status by 3 years, with the exception of one child from the severe group with ABO incompatibility with transient mild motor delay, hypotonia, and abnormal visual evoked potential. There were no abnormal effects of phototherapy on visual evoked potentials in infants with neonatal hyperbilirubinemia after 1 year of age. Although our sample size was small, the results suggest that the effects of hyperbilirubinemia on visual evoked potentials might be transient. (J Child Neurol 2006;21:58-62).

  5. Evoked potentials in the ICU.

    PubMed

    Amantini, A; Amadori, A; Fossi, S

    2008-01-01

    The most informative neurophysiological techniques available in the neurosurgical intensive care unit are electroencephalograph and somatosensory evoked potentials. Such tools, which give an evaluation of cerebral function in comatose patients, support clinical evaluation and are complementary to neuroimaging. They serve both diagnostic/prognostic and monitoring purposes. While for the former, discontinuous monitoring is sufficient, for the latter, to obtain increased clinical impact, continuous monitoring is necessary. To perform and interpret these examinations in the neurosurgical intensive care unit, both the technician and the neurophysiologist need specific training in the intensive care field. There is sufficient evidence to show that somatosensory evoked potentials are the best single indicator of early prognosis in traumatic and hypoxic-ischaemic coma compared to the Glasgow Coma Score, computed tomography scan and electroencephalograph. Indeed, somatosensory evoked potentials should always be combined with clinical examination to determine the prognosis of coma. Despite widespread use of somatosensory evoked potentials and their prognostic utility in acute brain injury, few studies exist on continuous somatosensory evoked potential monitoring in the intensive care unit. We carried out a pilot study of continuous electroencephalograph-somatosensory evoked potential monitoring in the neurosurgical intensive care unit (traumatic brain injury and intracranial haemorrhage, Glasgow Coma Score <9, intracranial pressure monitoring). All patients stable from a clinical and computed tomography scan point of view showed no significant somatosensory evoked potential modifications, while in the case of clinical deterioration (23%), somatosensory evoked potentials always showed significant modifications. While somatosensory evoked potentials correlated with short-term outcome, intracranial pressure showed a poor correlation. We believe neurophysiological monitoring is

  6. Single Trial Predictors for Gating Motor-Imagery Brain-Computer Interfaces Based on Sensorimotor Rhythm and Visual Evoked Potentials.

    PubMed

    Geronimo, Andrew; Kamrunnahar, Mst; Schiff, Steven J

    2016-01-01

    For brain-computer interfaces (BCIs) that utilize visual cues to direct the user, the neural signals extracted by the computer are representative of ongoing processes, visual evoked responses, and voluntary modulation. We proposed to use three brain signatures for predicting success on a single trial of a BCI task. The first two features, the amplitude and phase of the pre-trial mu amplitude, were chosen as a correlate for cortical excitability. The remaining feature, related to the visually evoked response to the cue, served as a possible measure of fixation and attention to the task. Of these three features, mu rhythm amplitude over the central electrodes at the time of cue presentation and to a lesser extent the single trial visual evoked response were correlated with the success on the subsequent imagery task. Despite the potential for gating trials using these features, an offline gating simulation was limited in its ability to produce an increase in device throughput. This discrepancy highlights a distinction between the identification of predictive features, and the use of this knowledge in an online BCI. Using such a system, we cannot assume that the user will respond similarly when faced with a scenario where feedback is altered by trials that are gated on a regular basis. The results of this study suggest the possibility of using individualized, pre-task neural signatures for personalized, and asynchronous (self-paced) BCI applications, although these effects need to be quantified in a real-time adaptive scenario in a future study.

  7. Post-tetanic transcranial motor evoked potentials augment the amplitude of compound muscle action potentials recorded from innervated and non-innervated muscles.

    PubMed

    Shigematsu, Hideki; Kawaguchi, Masahiko; Hayashi, Hironobu; Takatani, Tsunenori; Iwata, Eiichiro; Tanaka, Masato; Okuda, Akinori; Morimoto, Yasuhiko; Masuda, Keisuke; Yamamoto, Yusuke; Tanaka, Yasuhito

    2017-09-01

    Transcranial electrical stimulation used to produce motor evoked potentials (TES-MEPs) and subsequent compound muscle action potential (CMAP) recording is widely used to monitor motor function during surgery when there is risk of damaging the spinal cord. Nonetheless, some muscles do not produce CMAP amplitudes sufficient for intraoperative monitoring. This study aimed to investigate the utility of tetanic stimulation at single and multiple peripheral nerve sites for augmenting CMAP amplitudes recorded from innervated and non-innervated muscles. A retrospective study was carried out. The study sample comprised 24 patients with cervical myelopathy who underwent decompression surgery at our department between November 2005 and March 2007. Compound muscle action potential amplitude was a physiological measure. We used two patterns of tetanic peripheral nerve stimulation for each patient. The first pattern consisted of tetanic stimulation of the left tibial nerve only (Pattern 1), and the second pattern consisted of tetanic stimulation of the bilateral median nerves and left tibial nerve (Pattern 2). Compound muscle action potential amplitudes from all muscles were augmented by both tetanic stimulation patterns compared with conventional TES-MEP recording; however, Pattern 2 elicited the greatest augmentation of CMAP amplitudes, especially for CMAPs recorded from the bilateral abductor pollicis brevis muscles. Although tetanic stimulation of a single peripheral nerve increased CMAP amplitudes recorded from both innervated and non-innervated muscles, CMAP amplitudes were best augmented when the corresponding nerve received tetanic stimulation. Additionally, tetanic stimulation of multiple nerves rather than a single nerve appears to provide better augmentation. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Vestibular evoked myogenic potentials: review.

    PubMed

    Mudduwa, R; Kara, N; Whelan, D; Banerjee, Anirvan

    2010-10-01

    Disorders of balance often pose a diagnostic conundrum for clinicians, and a multitude of investigations have emerged over the years. Vestibular evoked myogenic potential testing is a diagnostic tool which can be used to assess vestibular function. Over recent years, extensive study has begun to establish a broader clinical role for vestibular evoked myogenic potential testing. To provide an overview of vestibular evoked myogenic potential testing, and to present the evidence for its clinical application. REVIEW TYPE: Structured literature search according to evidence-based medicine guidelines, performed between November 2008 and April 2009. No restrictions were applied to the dates searched. The benefits of vestibular evoked myogenic potential testing have already been established as regards the diagnosis and monitoring of several clinical conditions. Researchers continue to delve deeper into potential new clinical applications, with early results suggesting promising future developments.

  9. Single fibre motor evoked potentials to brain, spinal roots and nerve stimulation. Comparisons of the 'central' and 'peripheral' response jitter to magnetic and electric stimuli.

    PubMed

    Zarola, F; Caramia, M D; Paradiso, C; Mariorenzi, R; Martino, G; Traversa, R; Rossini, P M

    1989-08-28

    Single fibre motor evoked potentials to magnetic and electric non-invasive stimulation of brain, spinal cord and peripheral nerve were recorded in 8 healthy volunteers. The 'central motor jitter' and the 'peripheral motor jitter' were respectively calculated and a comparison between the magnetic and electric modalities was made. The highest degree of latency variability was observed for both magnetic and electric central motor jitter, whilst the peripheral motor jitter to nerve stimulation was as low as the neuromuscular one (range 16-60 microsecond). The magnetic 'central motor jitter' (range 94-1024 microsecond) was much larger than the electric one (range 55-280 microsecond), which was in the order of jitter calculated on H-reflex studies; moreover, the former was organized in a bi- or trimodal distribution. On the contrary, no significant differences were observed between the two modalities when the jitter to nerve stimulation was taken into account. Possible contributions of corticocortical circuitries containing several synaptic interruptions during magnetic as opposed to electric transcranial stimulation, is discussed.

  10. Transient and reproducible loss of motor-evoked potential signals after intravenous levetiracetam in a child undergoing craniotomy for resection of astrocytoma.

    PubMed

    Simpao, Allan F; Janik, Luke S; Hsu, Grace; Schwartz, Alan Jay; Heuer, Gregory G; Warrington, Andrew P; Rehman, Mohamed A

    2015-01-15

    Transcranial electrical motor-evoked potential (tceMEP) monitoring is used in complex intracranial and spinal surgeries to detect and prevent neurological injury. We present a case of transient, reproducible loss of tceMEPs after an infusion of levetiracetam during craniotomy and tumor resection in a child. Cessation of the infusion resulted in restoration of baseline tceMEPs. When the infusion was resumed at the end of the procedure, a similar decrease in tceMEPs was seen as before, after the infusion was stopped. The surgery and postoperative course proceeded without incident, and the patient experienced a full recovery.

  11. Single Trial Predictors for Gating Motor-Imagery Brain-Computer Interfaces Based on Sensorimotor Rhythm and Visual Evoked Potentials

    PubMed Central

    Geronimo, Andrew; Kamrunnahar, Mst; Schiff, Steven J.

    2016-01-01

    For brain-computer interfaces (BCIs) that utilize visual cues to direct the user, the neural signals extracted by the computer are representative of ongoing processes, visual evoked responses, and voluntary modulation. We proposed to use three brain signatures for predicting success on a single trial of a BCI task. The first two features, the amplitude and phase of the pre-trial mu amplitude, were chosen as a correlate for cortical excitability. The remaining feature, related to the visually evoked response to the cue, served as a possible measure of fixation and attention to the task. Of these three features, mu rhythm amplitude over the central electrodes at the time of cue presentation and to a lesser extent the single trial visual evoked response were correlated with the success on the subsequent imagery task. Despite the potential for gating trials using these features, an offline gating simulation was limited in its ability to produce an increase in device throughput. This discrepancy highlights a distinction between the identification of predictive features, and the use of this knowledge in an online BCI. Using such a system, we cannot assume that the user will respond similarly when faced with a scenario where feedback is altered by trials that are gated on a regular basis. The results of this study suggest the possibility of using individualized, pre-task neural signatures for personalized, and asynchronous (self-paced) BCI applications, although these effects need to be quantified in a real-time adaptive scenario in a future study. PMID:27199630

  12. Evoked potentials in multiple sclerosis.

    PubMed

    Kraft, George H

    2013-11-01

    Before the development of magnetic resonance imaging (MRI), evoked potentials (EPs)-visual evoked potentials, somatosensory evoked potentials, and brain stem auditory evoked responses-were commonly used to determine a second site of disease in patients being evaluated for possible multiple sclerosis (MS). The identification of an area of the central nervous system showing abnormal conduction was used to supplement the abnormal signs identified on the physical examination-thus identifying the "multiple" in MS. This article is a brief overview of additional ways in which central nervous system (CNS) physiology-as measured by EPs-can still contribute value in the management of MS in the era of MRIs. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Intraoperative monitoring during decompression of the spinal cord and spinal nerves using transcranial motor-evoked potentials: The law of twenty percent.

    PubMed

    Tanaka, Satoshi; Hirao, Jun; Oka, Hidehiro; Akimoto, Jiro; Takanashi, Junko; Yamada, Junichi

    2015-09-01

    Motor-evoked potential (MEP) monitoring was performed during 196 consecutive spinal (79 cervical and 117 lumbar) surgeries for the decompression of compressive spinal and spinal nerve diseases. MEP monitoring in spinal surgery has been considered sensitive to predict postoperative neurological recovery. In this series, transcranial stimulation consisted of trains of five pulses at a constant voltage (200-600 V). For the normalization of MEP, we recorded compound muscle action potentials (CMAP) after peripheral nerve stimulation, usually on the median nerve at the wrist 2 seconds before or after each transcranial stimulation of the motor area, for all operations. The sensitivity and specificity of MEP monitoring was 100% and 97.4%, respectively, or 96.9% with or without CMAP compensation (if the threshold of postoperative motor palsy was defined as 20% relative amplitude rate [RAR]). The mean RAR after CMAP normalization, of the most affected muscle in the patient group with excellent postoperative results (recovery rate of a Japan Orthopedic Association score of more than 50%) was significantly higher than that in the other groups (p=0.0224). All patients with an amplitude increase rate (AIR) with CMAP normalization of more than 20% achieved neurological recovery postoperatively. Our results suggest that if the RAR is more than 20%, postoperative motor palsy can be avoided in spinal surgery. If the AIR with normalization by CMAP after peripheral nerve stimulation is more than 20%, neurological recovery can be expected in spinal surgery.

  14. Higher success rate with transcranial electrical stimulation of motor-evoked potentials using constant-voltage stimulation compared with constant-current stimulation in patients undergoing spinal surgery.

    PubMed

    Shigematsu, Hideki; Kawaguchi, Masahiko; Hayashi, Hironobu; Takatani, Tsunenori; Iwata, Eiichiro; Tanaka, Masato; Okuda, Akinori; Morimoto, Yasuhiko; Masuda, Keisuke; Tanaka, Yuu; Tanaka, Yasuhito

    2017-05-05

    During spine surgery, the spinal cord is electrophysiologically monitored via transcranial electrical stimulation of motor-evoked potentials (TES-MEPs) to prevent injury. Transcranial electrical stimulation of motor-evoked potential involves the use of either constant-current or constant-voltage stimulation; however, there are few comparative data available regarding their ability to adequately elicit compound motor action potentials. We hypothesized that the success rates of TES-MEP recordings would be similar between constant-current and constant-voltage stimulations in patients undergoing spine surgery. The objective of this study was to compare the success rates of TES-MEP recordings between constant-current and constant-voltage stimulation. This is a prospective, within-subject study. Data from 100 patients undergoing spinal surgery at the cervical, thoracic, or lumbar level were analyzed. The success rates of the TES-MEP recordings from each muscle were examined. Transcranial electrical stimulation with constant-current and constant-voltage stimulations at the C3 and C4 electrode positions (international "10-20" system) was applied to each patient. Compound muscle action potentials were bilaterally recorded from the abductor pollicis brevis (APB), deltoid (Del), abductor hallucis (AH), tibialis anterior (TA), gastrocnemius (GC), and quadriceps (Quad) muscles. The success rates of the TES-MEP recordings from the right Del, right APB, bilateral Quad, right TA, right GC, and bilateral AH muscles were significantly higher using constant-voltage stimulation than those using constant-current stimulation. The overall success rates with constant-voltage and constant-current stimulations were 86.3% and 68.8%, respectively (risk ratio 1.25 [95% confidence interval: 1.20-1.31]). The success rates of TES-MEP recordings were higher using constant-voltage stimulation compared with constant-current stimulation in patients undergoing spinal surgery. Copyright © 2017

  15. Intraoperative Motor-Evoked Potential Disappearance versus Amplitude-Decrement Alarm Criteria During Cervical Spinal Surgery: A Long-Term Prognosis

    PubMed Central

    Kim, Dong-Gun; Choi, Young-Doo; Jin, Seung-Hyun; Kim, Chi Heon; Lee, Kwang-Woo; Park, Kyung Seok

    2017-01-01

    Background and Purpose We studied the clinical significance of amplitude-reduction and disappearance alarm criteria for transcranial electric muscle motor-evoked potentials (MEPs) during cervical spinal surgery according to different lesion locations [intramedullary (IM) vs. nonintramedullary (NIM)] by evaluating the long-term postoperative motor status. Methods In total, 723 patients were retrospectively dichotomized into the IM and NIM groups. Each limb was analyzed respectively. One hundred and sixteen limbs from 30 patients with IM tumors and 2,761 limbs from 693 patients without IM tumors were enrolled. Postoperative motor deficits were assessed up to 6 months after surgery. Results At the end of surgery, 61 limbs (2.2%) in the NIM group and 14 limbs (12.1%) in the IM group showed MEP amplitudes that had decreased to below 50% of baseline, with 13 of the NIM limbs (21.3%) and 2 of the IM limbs (14.3%) showing MEP disappearance. Thirteen NIM limbs (0.5%) and 5 IM limbs (4.3%) showed postoperative motor deficits. The criterion for disappearance showed a lower sensitivity for the immediate motor deficit than did the criterion for amplitude decrement in both the IM and NIM groups. However, the disappearance criterion showed the same sensitivity as the 70%-decrement criterion in IM (100%) and NIM (83%) surgeries for the motor deficit at 6 months after surgery. Moreover, it has the highest specificity for the motor deficits among diverse alarm criteria, from 24 hours to 6 months after surgery, in both the IM and NIM groups. Conclusions The MEP disappearance alarm criterion had a high specificity in predicting the long-term prognosis after cervical spinal surgery. However, because it can have a low sensitivity in predicting an immediate postoperative deficit, combining different MEP alarm criteria according to the aim of specific instances of cervical spinal surgery is likely to be useful in practical intraoperative monitoring. PMID:27730765

  16. [Evoked potentials monitoring in aortic surgery].

    PubMed

    Shiiya, Norihiko; Takahashi, Daisuke; Tsuda, Kazumasa

    2014-07-01

    Somatosensory evoked potential (SSEP), evoked spinal cord potential (ESCP) and motor evoked potential (MEP) have been used to detect spinal cord ischemia during aortic surgery. SSEP evaluates the sensory pathway, and is recorded from the sensory cortex by peripheral nerve stimulation. The interval from the onset of ischemia to change is relatively long(5-10 minutes). It has less frequently been used because of the high false negative and false positive rate. ESCP is recorded from the spinal cord by direct stimulation of the cord. It reflects the function of spinal tract but not that of alpha motor neurons. It is resistant to anesthesia and both the sensitivity and specificity is high, but the interval from ischemia to change is relatively long. Together with the necessity of 2 epidural electrodes, its application in aortic surgery has become infrequent. Since the introduction of train pulse transcranial electrical stimulation, myogenic MEP have gained widespread acceptance. It evaluates motor pathways from the cortex to the muscle, and therefore is influenced by non-spinal factors such as peripheral nerve ischemia. Its vulnerability to anesthesia requires special anesthetic consideration, and baseline amplitude fluctuation is common. It is highly sensitive and shows changes in the early phase of spinal cord ischemia.

  17. A role for motor and somatosensory evoked potentials during anterior cervical discectomy and fusion for patients without myelopathy: Analysis of 57 consecutive cases

    PubMed Central

    Xu, Risheng; Ritzl, Eva K.; Sait, Mohammed; Sciubba, Daniel M.; Wolinsky, Jean-Paul; Witham, Timothy F.; Gokaslan, Ziya L.; Bydon, Ali

    2011-01-01

    Background: Although the usage of combined motor and sensory intraoperative monitoring has been shown to improve the surgical outcome of patients with cervical myelopathy, the role of transcranial electric motor evoked potentials (tceMEP) used in conjunction with somatosensory evoked potentials (SSEP) in patients presenting with radiculopathy but without myelopathy has been less clear. Methods: We retrospectively reviewed all patients (n = 57) with radiculopathy but without myelopathy, undergoing anterior cervical decompression and fusion at a single institution over the past 3 years, who had intraoperative monitoring with both tceMEPs and SSEPs. Results: Fifty-seven (100%) patients presented with radiculopathy, 53 (93.0%) with mechanical neck pain, 35 (61.4%) with motor dysfunction, and 29 (50.9%) with sensory deficits. Intraoperatively, 3 (5.3%) patients experienced decreases in SSEP signal amplitudes and 4 (6.9%) had tceMEP signal changes. There were three instances where a change in neuromonitoring signal required intraoperative alteration of the surgical procedure: these were deemed clinically significant events/true positives. SSEP monitoring showed two false positives and two false negatives, whereas tceMEP monitoring only had one false positive and no false negatives. Thus, tceMEP monitoring exhibited higher sensitivity (33.3% vs. 100%), specificity (95.6% vs. 98.1%), positive predictive value (33.3% vs. 75.0%), negative predictive value (97.7% vs. 100%), and efficiency (91.7% vs. 98.2%) compared to SSEP monitoring alone. Conclusions: Here, we present a retrospective series of 57 patients where tceMEP/SSEP monitoring likely prevented irreversible neurologic damage. Though further prospective studies are needed, there may be a role for combined tceMEP/SSEP monitoring for patients undergoing anterior cervical decompression without myelopathy. PMID:22059128

  18. Comparison of effectiveness between cork-screw and peg-screw electrodes for transcranial motor evoked potential monitoring using the finite element method

    PubMed Central

    Tomio, Ryosuke; Akiyama, Takenori; Ohira, Takayuki; Yoshida, Kazunari

    2016-01-01

    Background: Intraoperative monitoring of motor evoked potentials by transcranial electric stimulation is popular in neurosurgery for monitoring motor function preservation. Some authors have reported that the peg-screw electrodes screwed into the skull can more effectively conduct current to the brain compared to subdermal cork-screw electrodes screwed into the skin. The aim of this study was to investigate the influence of electrode design on transcranial motor evoked potential monitoring. We estimated differences in effectiveness between the cork-screw electrode, peg-screw electrode, and cortical electrode to produce electric fields in the brain. Methods: We used the finite element method to visualize electric fields in the brain generated by transcranial electric stimulation using realistic three-dimensional head models developed from T1-weighted images. Surfaces from five layers of the head were separated as accurately as possible. We created the “cork-screws model,” “1 peg-screw model,” “peg-screws model,” and “cortical electrode model”. Results: Electric fields in the brain radially diffused from the brain surface at a maximum just below the electrodes in coronal sections. The coronal sections and surface views of the brain showed higher electric field distributions under the peg-screw compared to the cork-screw. An extremely high electric field was observed under cortical electrodes. Conclusion: Our main finding was that the intensity of electric fields in the brain are higher in the peg-screw model than the cork-screw model. PMID:27920938

  19. Evoked Potentials and Human Intelligence.

    ERIC Educational Resources Information Center

    Ertl, John P.; Schafer, Edward W. P.

    Evidence of a relationship between the electrical responses of the human brain and psychometric measure of intelligence is presented. These involuntary cortical responses, known as average evoked potentials are considered to be the electrical signs of information processing by the brain. The time delays of these responses from presentation of a…

  20. Deep Brain Stimulation of the Lateral Cerebellar Nucleus Produces Frequency-Specific Alterations in Motor Evoked Potentials in the Rat In Vivo

    PubMed Central

    Baker, Kenneth B.; Schuster, Daniel; Cooperrider, Jessica; Machado, Andre G.

    2010-01-01

    The cerebral cortex is tightly and reciprocally linked to the cerebellum and the ascending dentato-thalalmo-cortical pathway influences widespread cortical regions. Using a rodent model of middle cerebral artery stroke, we showed previously that chronic, 20 Hz stimulation of the contralateral lateral cerebellar nucleus (LCN) improved motor recovery, while 50 Hz stimulation did not. Using motor evoked potentials (MEP) elicited by intracortical microstimulation, we now show the effect of LCN stimulation on motor cortex excitability as a function of pulse frequency in propofol-anesthetized rats. MEPs were recorded serially, at 15-second intervals, with cerebellar stimulation delivered in 10-minute blocks at rates of 20, 30, 40, 50 or 100 Hz. Stimulation at 20, 30, 40 or 50 Hz enhanced the average MEP response across the block, with the maximal overall increase observed during 30 Hz stimulation. However, the effect varied as a function of both repeated trials within the block and LCN stimulation frequency, such that 40 Hz and 50 Hz stimulation showed a reduced effect over time. Stimulation at 100 Hz produced a transient increase in MEP amplitude in some animals; however the overall effect across the block was a trend towards reduced cortical excitability. These results suggest that direct stimulation of the LCN can yield frequency-dependent changes in cortical excitability and may provide a therapeutic approach to modulating cortical activity for the treatment of strokes or other focal cortical lesions, movement disorders and epilepsy. PMID:20816822

  1. Effect of inter-train interval on the induction of repetition suppression of motor-evoked potentials using transcranial magnetic stimulation.

    PubMed

    Pitkänen, Minna; Kallioniemi, Elisa; Julkunen, Petro

    2017-01-01

    Repetition suppression (RS) is evident as a weakened response to repeated stimuli after the initial response. RS has been demonstrated in motor-evoked potentials (MEPs) induced with transcranial magnetic stimulation (TMS). Here, we investigated the effect of inter-train interval (ITI) on the induction of RS of MEPs with the attempt to optimize the investigative protocols. Trains of TMS pulses, targeted to the primary motor cortex by neuronavigation, were applied at a stimulation intensity of 120% of the resting motor threshold. The stimulus trains included either four or twenty pulses with an inter-stimulus interval (ISI) of 1 s. The ITI was here defined as the interval between the last pulse in a train and the first pulse in the next train; the ITIs used here were 1, 3, 4, 6, 7, 12, and 17 s. RS was observed with all ITIs except with the ITI of 1 s, in which the ITI was equal to ISI. RS was more pronounced with longer ITIs. Shorter ITIs may not allow sufficient time for a return to baseline. RS may reflect a startle-like response to the first pulse of a train followed by habituation. Longer ITIs may allow more recovery time and in turn demonstrate greater RS. Our results indicate that RS can be studied with confidence at relatively short ITIs of 6 s and above.

  2. A multi-train electrical stimulation protocol facilitates transcranial electrical motor evoked potentials and increases induction rate and reproducibility even in patients with preoperative neurological deficits.

    PubMed

    Ushio, Shuta; Kawabata, Shigenori; Sumiya, Satoshi; Kato, Tsuyoshi; Yoshii, Toshitaka; Yamada, Tsuyoshi; Enomoto, Mitsuhiro; Okawa, Atsushi

    2017-07-14

    This study sought to evaluate the facilitation effect of repetitive multi-train transcranial electrical stimulation (mt-TES) at 2 repetition rates on transcranial electrical motor evoked potential (Tc-MEP) monitoring during spinal surgery, and to assess the induction rate in patients with impaired motor function from a compromised spinal cord or spinal nerve. We studied 32 consecutive patients with impaired motor function undergoing cervical or thoracic spinal surgery (470 muscles). A series of 10 TESs with 5 pulse trains were preoperatively delivered at 2 repetition rates (1 and 5 Hz). All peak-topeak amplitudes of the MEPs of the upper and lower extremity muscles elicited by the 10 TESs were measured. The induction rates of the lower extremity muscles were also assessed with muscle and preoperative lower extremity motor function scores. In each of the muscles, MEP amplitudes were augmented by about 2-3 times at 1 Hz and 5-6 times at 5 Hz. Under the 5-Hz condition, all limb muscles showed significant amplification. Also, in all preoperative motor function score groups, the amplitudes and induction rates of the lower extremity muscles were significantly increased. Moreover, the facilitation effects tended to peak in the last half of the series of 10 TESs. In all score groups of patients with preoperative neurological deficits, repetitive mt-TES delivered at a frequency of 5 Hz markedly facilitated the MEPs of all limb muscles and increased the induction rate. We recommend this method to improve the reliability of intraoperative monitoring during spinal surgery.

  3. Effects of left primary motor and dorsolateral prefrontal cortex transcranial direct current stimulation on laser-evoked potentials in migraine patients and normal subjects.

    PubMed

    Vecchio, Eleonora; Ricci, Katia; Montemurno, Anna; Delussi, Marianna; Invitto, Sara; de Tommaso, Marina

    2016-07-28

    Migraine is characterized by an altered cortical excitability. Because transcranial direct current stimulation (tDCS) can change brain activity noninvasively, it is possible to hypothesize its efficacy in modulating pain in migraine. In this study, we compared the effects of tDCS of the left primary motor cortex (M1) and left dorsolateral prefrontal cortex (DLPFC) both on subjective pain and on evoked responses induced by laser stimulation (LEPs). Thirty-two patients and sixteen controls were randomized to receive sham stimulation and real tDCS with the anode centered over M1 or DLPFC. Laser Evoked potentials were recorded in basal, sham and tDCS conditions. We did not find significant acute changes in LEPs parameters and pain perception among subjects who received tDCS of both M1 and DLPFC. After DLPFC tDCS, we observed a significant increase of N2-P2 component habituation in migraine patients while M1 stimulation reduced it. These findings may suggest a modulation of abnormal pain processing induced by DLPFC and M1 anodal tDCS and outline the need for future investigations exploring the possible neuronal plasticity changes supporting the clinical effect on migraine.

  4. Vestibular-evoked myogenic potentials.

    PubMed

    Colebatch, J G; Rosengren, S M; Welgampola, M S

    2016-01-01

    The vestibular-evoked myogenic potential (VEMP) is a short-latency potential evoked through activation of vestibular receptors using sound or vibration. It is generated by modulated electromyographic signals either from the sternocleidomastoid muscle for the cervical VEMP (cVEMP) or the inferior oblique muscle for the ocular VEMP (oVEMP). These reflexes appear to originate from the otolith organs and thus complement existing methods of vestibular assessment, which are mainly based upon canal function. This review considers the basis, methodology, and current applications of the cVEMP and oVEMP in the assessment and diagnosis of vestibular disorders, both peripheral and central. © 2016 Elsevier B.V. All rights reserved.

  5. Time Perception and Evoked Potentials

    DTIC Science & Technology

    1988-07-01

    settlement of beat - sound syn- chronization with cadences or rhythms is very fast, and simultaneity is already carried out on the third stimulus. In the...During the binaural listening of the stimulations (empty durations delimited by clicks), the auditory evoked potentials (AEP) of the subjects were re...1974a), the stimulus duration (HUANG, 1981), the stimulation delivery way, monaural or binaural (ALLEN, 1968) or the . stimulus probability (FITZGERALD

  6. Pre-stimulus Alpha Oscillations and Inter-subject Variability of Motor Evoked Potentials in Single- and Paired-Pulse TMS Paradigms

    PubMed Central

    Iscan, Zafer; Nazarova, Maria; Fedele, Tommaso; Blagovechtchenski, Evgeny; Nikulin, Vadim V.

    2016-01-01

    Inter- and intra-subject variability of the motor evoked potentials (MEPs) to TMS is a well-known phenomenon. Although a possible link between this variability and ongoing brain oscillations was demonstrated, the results of the studies are not consistent with each other. Exploring this topic further is important since the modulation of MEPs provides unique possibility to relate oscillatory cortical phenomena to the state of the motor cortex probed with TMS. Given that alpha oscillations were shown to reflect cortical excitability, we hypothesized that their power and variability might explain the modulation of subject-specific MEPs to single- and paired-pulse TMS (spTMS, ppTMS, respectively). Neuronal activity was recorded with multichannel electroencephalogram. We used spTMS and two ppTMS conditions: intracortical facilitation (ICF) and short-interval intracortical inhibition (SICI). Spearman correlations were calculated within and across subjects between MEPs and the pre-stimulus power of alpha oscillations in low (8–10 Hz) and high (10–12 Hz) frequency bands. Coefficient of quartile variation was used to measure variability. Across-subject analysis revealed no difference in the pre-stimulus alpha power among the TMS conditions. However, the variability of high-alpha power in spTMS condition was larger than in the SICI condition. In ICF condition pre-stimulus high-alpha power variability correlated positively with MEP amplitude variability. No correlation has been observed between the pre-stimulus alpha power and MEP responses in any of the conditions. Our results show that the variability of the alpha oscillations can be more predictive of TMS effects than the commonly used power of oscillations and we provide further support for the dissociation of high and low-alpha bands in predicting responses produced by the stimulation of the motor cortex. PMID:27774060

  7. Pre-stimulus Alpha Oscillations and Inter-subject Variability of Motor Evoked Potentials in Single- and Paired-Pulse TMS Paradigms.

    PubMed

    Iscan, Zafer; Nazarova, Maria; Fedele, Tommaso; Blagovechtchenski, Evgeny; Nikulin, Vadim V

    2016-01-01

    Inter- and intra-subject variability of the motor evoked potentials (MEPs) to TMS is a well-known phenomenon. Although a possible link between this variability and ongoing brain oscillations was demonstrated, the results of the studies are not consistent with each other. Exploring this topic further is important since the modulation of MEPs provides unique possibility to relate oscillatory cortical phenomena to the state of the motor cortex probed with TMS. Given that alpha oscillations were shown to reflect cortical excitability, we hypothesized that their power and variability might explain the modulation of subject-specific MEPs to single- and paired-pulse TMS (spTMS, ppTMS, respectively). Neuronal activity was recorded with multichannel electroencephalogram. We used spTMS and two ppTMS conditions: intracortical facilitation (ICF) and short-interval intracortical inhibition (SICI). Spearman correlations were calculated within and across subjects between MEPs and the pre-stimulus power of alpha oscillations in low (8-10 Hz) and high (10-12 Hz) frequency bands. Coefficient of quartile variation was used to measure variability. Across-subject analysis revealed no difference in the pre-stimulus alpha power among the TMS conditions. However, the variability of high-alpha power in spTMS condition was larger than in the SICI condition. In ICF condition pre-stimulus high-alpha power variability correlated positively with MEP amplitude variability. No correlation has been observed between the pre-stimulus alpha power and MEP responses in any of the conditions. Our results show that the variability of the alpha oscillations can be more predictive of TMS effects than the commonly used power of oscillations and we provide further support for the dissociation of high and low-alpha bands in predicting responses produced by the stimulation of the motor cortex.

  8. Efficacy and safety of novel high-frequency multi-train stimulation for recording transcranial motor evoked potentials in a rat model.

    PubMed

    Deguchi, Tsuyoshi; Tsutsui, Shunji; Iwahashi, Hiroki; Nakagawa, Yukihiro; Yoshida, Munehito

    2016-08-26

    Recently, low-frequency multi-train stimulation (MTS) was shown to effectively enhance transcranial motor-evoked potentials (TcMEPs). In contrast, high- frequency double-train stimulation was reported to elicit a marked facilitation. The aim of this study was to evaluate the efficacy of high-frequency MTS in the augmentation of potentials. In addition, we investigated the safety of high-frequency MTS, behaviorally and histologically. TcMEPs were recorded from the triceps surae muscle in 38 rats. A multipulse stimulus was delivered repeatedly at different rates (2, 5, 10, 20, and 50 Hz), and was defined as MTS. A conditioned taste aversion method was used to investigate the effect of high-frequency MTS on learning and memory function. Subsequently, animals were sacrificed, and the brains were removed and examined using the standard hematoxylin-eosin method. Compared with conventional single train stimulation, TcMEP amplitudes increased 1.3, 2.1, 1.9, and 2.0 times on average with 5, 10, 20, and 50 Hz stimulation, respectively. The aversion index was >0.8 in all animals after they received 100 high-frequency MTSs. Histologically, no pathological changes were evident in the rat brains. High-frequency MTS shows potential to effectively enhance TcMEP responses, and to be used safely in transcranial brain stimulation.

  9. Effects of a common transcranial direct current stimulation (tDCS) protocol on motor evoked potentials found to be highly variable within individuals over 9 testing sessions.

    PubMed

    Horvath, Jared Cooney; Vogrin, Simon J; Carter, Olivia; Cook, Mark J; Forte, Jason D

    2016-09-01

    Transcranial direct current stimulation (tDCS) uses a weak electric current to modulate neuronal activity. A neurophysiologic outcome measure to demonstrate reliable tDCS modulation at the group level is transcranial magnetic stimulation engendered motor evoked potentials (MEPs). Here, we conduct a study testing the reliability of individual MEP response patterns following a common tDCS protocol. Fourteen participants (7m/7f) each underwent nine randomized sessions of 1 mA, 10 min tDCS (3 anode; 3 cathode; 3 sham) delivered using an M1/orbito-frontal electrode montage (sessions separated by an average of ~5.5 days). Fifteen MEPs were obtained prior to, immediately following and in 5 min intervals for 30 min following tDCS. TMS was delivered at 130 % resting motor threshold using neuronavigation to ensure consistent coil localization. A number of non-experimental variables were collected during each session. At the individual level, considerable variability was seen among different testing sessions. No participant demonstrated an excitatory response ≥20 % to all three anodal sessions, and no participant demonstrated an inhibitory response ≥20 % to all three cathodal sessions. Intra-class correlation revealed poor anodal and cathodal test-retest reliability [anode: ICC(2,1) = 0.062; cathode: ICC(2,1) = 0.055] and moderate sham test-retest reliability [ICC(2,1) = 0.433]. Results also revealed no significant effect of tDCS at the group level. Using this common protocol, we found the effects of tDCS on MEP amplitudes to be highly variable at the individual level. In addition, no significant effects of tDCS on MEP amplitude were found at the group level. Future studies should consider utilizing a more strict experimental protocol to potentially account for intra-individual response variations.

  10. Subcortical evoked activity and motor enhancement in Parkinson's disease

    PubMed Central

    Anzak, Anam; Tan, Huiling; Pogosyan, Alek; Khan, Sadaquate; Javed, Shazia; Gill, Steven S.; Ashkan, Keyoumars; Akram, Harith; Foltynie, Thomas; Limousin, Patricia; Zrinzo, Ludvic; Green, Alexander L.; Aziz, Tipu; Brown, Peter

    2016-01-01

    Enhancements in motor performance have been demonstrated in response to intense stimuli both in healthy subjects and in the form of ‘paradoxical kinesis’ in patients with Parkinson's disease. Here we identify a mid-latency evoked potential in local field potential recordings from the region of the subthalamic nucleus, which scales in amplitude with both the intensity of the stimulus delivered and corresponding enhancements in biomechanical measures of maximal handgrips, independent of the dopaminergic state of our subjects with Parkinson's disease. Recordings of a similar evoked potential in the related pedunculopontine nucleus – a key component of the reticular activating system – provide support for this neural signature in the subthalmic nucleus being a novel correlate of ascending arousal, propagated from the reticular activating system to exert an ‘energizing’ influence on motor circuitry. Future manipulation of this system linking arousal and motor performance may provide a novel approach for the non-dopaminergic enhancement of motor performance in patients with hypokinetic disorders such as Parkinson's disease. PMID:26687971

  11. Subcortical evoked activity and motor enhancement in Parkinson's disease.

    PubMed

    Anzak, Anam; Tan, Huiling; Pogosyan, Alek; Khan, Sadaquate; Javed, Shazia; Gill, Steven S; Ashkan, Keyoumars; Akram, Harith; Foltynie, Thomas; Limousin, Patricia; Zrinzo, Ludvic; Green, Alexander L; Aziz, Tipu; Brown, Peter

    2016-03-01

    Enhancements in motor performance have been demonstrated in response to intense stimuli both in healthy subjects and in the form of 'paradoxical kinesis' in patients with Parkinson's disease. Here we identify a mid-latency evoked potential in local field potential recordings from the region of the subthalamic nucleus, which scales in amplitude with both the intensity of the stimulus delivered and corresponding enhancements in biomechanical measures of maximal handgrips, independent of the dopaminergic state of our subjects with Parkinson's disease. Recordings of a similar evoked potential in the related pedunculopontine nucleus - a key component of the reticular activating system - provide support for this neural signature in the subthalmic nucleus being a novel correlate of ascending arousal, propagated from the reticular activating system to exert an 'energizing' influence on motor circuitry. Future manipulation of this system linking arousal and motor performance may provide a novel approach for the non-dopaminergic enhancement of motor performance in patients with hypokinetic disorders such as Parkinson's disease.

  12. Do pursuit movement tasks lead to differential changes in early somatosensory evoked potentials related to motor learning compared with typing tasks?

    PubMed

    Andrew, Danielle; Yielder, Paul; Murphy, Bernadette

    2015-02-15

    Central nervous system (CNS) plasticity is essential for development; however, recent research has demonstrated its role in pathology, particularly following overuse and repetition. Previous studies investigating changes in sensorimotor integration (SMI) have used relatively simple paradigms resulting in minimal changes in neural activity, as determined through the use of somatosensory evoked potentials (SEPs). This study sought to utilize complex tasks and compare separate motor paradigms to determine which one best facilitates long-term learning. Spinal, brainstem, and cortical SEPs were recorded following median nerve stimulation at the wrist pre- and postinterventions. Eighteen participants performed the same paradigms, a control condition of 10 min of mental recitation and two interventions, one consisting of 10 min of tracing and the other 10 min of repetitive typing. Significant increases in the N13, N20, P25, and N30 SEP peaks were seen for both interventions. A significant decrease in the N24 SEP peak was observed for both interventions. Significant improvements in accuracy were seen for both interventions postacquisition but only for tracing during retention. The changes seen following motor learning were congruent with those associated with long-term learning, which was also reflected by significant increases in accuracy during retention. Tracing or the pursuit movement paradigm was shown to be a more effective learning tool. The identification of a task that is sufficiently novel and complex, leading to robust changes in SEP peaks, indicates a task that can be utilized in future work to study clinical populations and the effect of experimental interventions on SMI. Copyright © 2015 the American Physiological Society.

  13. Magnetic stimulation of biceps after intercostal cross-innervation for brachial plexus palsy. A study of motor evoked potentials in 25 patients.

    PubMed

    Kawai, H; Murase, T; Shibuya, R; Kawabata, H; Yonenobu, K; Masatomi, T; Ono, K

    1994-07-01

    We studied the motor evoked potentials (MEP) in the biceps of 25 patients with traumatic brachial plexus palsy from root avulsion after cross-innervation by intercostal nerves. We used transcranial, transcervical and transthoracic magnetic stimulation at 8 to 235 months (mean 51) after transfer of intercostal nerves to the musculocutaneous nerve. Biceps strength recovered to MRC grade 2 in eight patients, grade 3 in three and grade 4 in 14. The mean latency of the MEP in the normal biceps on transcranial stimulation was 12.5 +/- 1.3 ms and on transcervical stimulation 6.3 +/- 1.1 ms. After intercostal reinnervation the mean latency on transcranial stimulation was 21.7 +/- 4.5 ms and on transthoracic stimulation 11.6 +/- 3.8 ms. The latency of the biceps MEP after reinnervation by intercostal nerves on transcranial and transthoracic magnetic stimulation correlated well with the duration of follow-up and the latency of the MEP on transthoracic magnetic stimulation correlated significantly with muscle power.

  14. Evaluation of the Predictive Value of Intraoperative Changes in Motor-Evoked Potentials of Caudal Cranial Nerves for the Postoperative Functional Outcome.

    PubMed

    Kullmann, Marcel; Tatagiba, Marcos; Liebsch, Marina; Feigl, Guenther C

    2016-11-01

    The predictive value of changes in intraoperatively acquired motor-evoked potentials (MEPs) of the lower cranial nerves (LCN) IX-X (glossopharyngeal-vagus nerve) and CN XII (hypoglossal nerve) on operative outcomes was investigated. MEPs of CN IX-X and CN XII were recorded intraoperatively in 63 patients undergoing surgery of the posterior cranial fossa. We correlated the changes of the MEPs with postoperative nerve function. For CN IX-X, we found a correlation between the amplitude of the MEP ratio and uvula deviation (P = 0.028) and the amplitude duration of the MEP and gag reflex function (P = 0.027). Patients with an MEP ratio of the glossopharyngeal-vagus amplitude ≤1.47 μV had a 3.4 times increased risk of developing a uvula deviation. Patients with a final MEP duration of the CN IX-X ≤11.6 milliseconds had a 3.6 times increased risk for their gag reflex to become extinct. Our study greatly contributes to the current knowledge of intraoperative MEPs as a predictor for postoperative cranial nerve function. We were able to extent previous findings on MEP values of the facial nerve on postoperative nerve function to 3 additional cranial nerves. Finding reliable predictors for postoperative nerve function is of great importance to the overall quality of life for a patient undergoing surgery of the posterior cranial fossa. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Effects of Dexmedetomidine on motor- and somatosensory-evoked potentials in patients with thoracic spinal cord tumor: a randomized controlled trial.

    PubMed

    Li, Yan; Meng, Lingzhong; Peng, Yuming; Qiao, Hui; Guo, Lanjun; Han, Ruquan; Gelb, Adrian W

    2016-08-02

    We hypothesized that the addition of dexmedetomidine in a clinically relevant dose to propofol-remifentanil anesthesia regimen does not exert an adverse effect on motor-evoked potentials (MEP) and somatosensory-evoked potentials (SSEP) in adult patients undergoing thoracic spinal cord tumor resection. Seventy-one adult patients were randomized into three groups. Propofol group (n = 25): propofol-remifentanil regimenand the dosage was adjusted to maintain the bispectral index (BIS) between 40 and 50. DP adjusted group (n = 23): Dexmedetomidine (0.5 μg/kg loading dose infused over 10 min followed by a constant infusion of 0.5 μg/kg/h) was added to the propofol-remifentanil regimen and propofol was adjusted to maintain BIS between 40 and 50. DP unadjusted group (n = 23): Dexmedetomidine (administer as DP adjusted group) was added to the propofol-remifentanil regimen and propofol was not adjusted. All patients received MEP, SSEP and BIS monitoring. There were no significant changes in the amplitude and latency of MEP and SSEP among different groups (P > 0.05). The estimated propofol plasma concentration in DP adjusted group (2.7 ± 0.3 μg/ml) was significantly lower than in propofol group (3.1 ± 0.2 μg/ml) and DP unadjusted group (3.1 ± 0.2 μg/ml) (P = 0.000). BIS in DP unadjusted group (35 ± 5) was significantly lower than in propofol group (44 ± 3) (P = 0.000). The addition of dexmedetomidine to propofol-remifentanil regimen does not exert an adverse effect on MEP and SSEP monitoring in adult patients undergoing thoracic spinal cord tumor resection. The study was registered with the Chinese Clinical Trial Registry on January 31st, 2014. The reference number was ChiCTR-TRC-14004229.

  16. Using Transcranial Magnetic Stimulation to Evaluate the Motor Pathways After an Intraoperative Spinal Cord Injury and to Predict the Recovery of Intraoperative Transcranial Electrical Motor Evoked Potentials: A Case Report.

    PubMed

    Grover, Helen J; Thornton, Rachel; Lutchman, Lennel N; Blake, Julian C

    2016-06-01

    The authors report a case of unilateral loss of intraoperative transcranial electrical motor evoked potentials (TES MEP) associated with a spinal cord injury during scoliosis correction and the subsequent use of extraoperative transcranial magnetic stimulation to monitor the recovery of spinal cord function. The authors demonstrate the absence of TES MEPs and absent transcranial magnetic stimulation responses in the immediate postoperative period, and document the partial recovery of transcranial magnetic stimulation responses, which corresponded to partial recovery of TES MEPs. Intraoperative TES MEPs were enhanced using spatial facilitation technique, which enabled the patient to undergo further surgery to stabilize the spine and correct her scoliosis. This case report supports evidence of the use of extraoperative transcranial magnetic stimulation to predict the presence of intraoperative TES responses and demonstrates the usefulness of spatial facilitation to monitor TES MEPs in a patient with a preexisting spinal cord injury.

  17. Facilitation of motor evoked potentials from magnetic brain stimulation in man: a comparative study of different target muscles.

    PubMed

    Kischka, U; Fajfr, R; Fellenberg, T; Hess, C W

    1993-10-01

    The influence of tonic muscle contraction and stimulus intensity on compound muscle action potentials (CMAPs) elicited by magnetic brain stimulation was studied in the biceps brachii (34 subjects), the abductor digiti minimi (11 subjects), the anterior tibial muscle (12 subjects), and the soleus muscle (5 subjects). The muscles were examined at rest and with various degrees of background contraction of up to 60% of maximum force. Stimulus intensity was set at threshold (TSI) or 20% above threshold (1.2 TSI), and in one series additionally at 50% above threshold (1.5 TSI). The effect of voluntary background contraction on CMAP onset latency was similar in the four muscles tested: the latencies shortened by approximately 3 ms when the muscle changed from the relaxed to the contracted state of the 10% of maximum force. An additional increase in the background contraction up to 60% of maximum force induced only few, if any, additional decreases in latency. The uniformity of the latency shift in distal and proximal muscles conflicts with the idea of recruitment of larger and rapidly conducting motoneurons being the cause, since this hypothesis would imply a more pronounced latency reduction in distal than in proximal muscles. The shorter latency during voluntary contraction is more likely due to an enhanced synaptic efficacy at spinal level. Since the motoneurons are brought into an increased state of activity during contraction, they require less temporal summation to reach firing threshold and thus discharge earlier. The CMAP amplitudes of the different muscles were more distinctly affected by voluntary background contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Continuous distraction-induced delayed spinal cord injury on motor-evoked potentials and histological changes of spinal cord in a porcine model.

    PubMed

    Hong, J-Y; Suh, S-W; Lee, S-H; Park, J-H; Park, S-Y; Rhyu, I J; Yang, J-H

    2016-09-01

    Experimental study. This study evaluated distraction-induced delayed spinal cord injury in a porcine model. Department of Orthopedics, Korea University Guro Hospital, Seoul, Korea. Global osteotomy of three columns was performed on the thirteenth thoracic vertebrae with 13 pigs. The osteotomized vertebrae were distracted to 57-103% of segmental vertebral height (SVH) length, which was less than the distraction length that induces prompt SCI. The vertebral height was maintained until the loss of motor-evoked potential (MEP) signals with continuous distraction. The distraction distance and the time at which SCI occurred were measured, and distraction was then released to observe MEP recovery patterns. We found delayed SCI in 8 of the 12 pigs, with a mean 20.9 mm (range 19-25 mm) and 10.7 min (range 8-12 min) of continuous spinal distraction, which was equivalent to 74.3% (68-84%) of SVH and 3.63% (3.42-4.31%) of thoracolumbar spinal length. A continuous 74.3% SVH distraction over an average of 10.7 min caused a delayed SCI, which was indicated by mild histologic changes in the spinal cord. Recovery patterns from SCI after distraction release were compatible with the degree of histological change; however, these patterns differed from the previously investigated prompt type of SCI. Late onset injury due to continuous spinal distraction, which is comparable to iatrogenic SCI in spinal correction surgery, is important for understanding the impact of corrective surgery.

  19. Setting up and utilizing a service for measuring perioperative transcranial motor evoked potentials during thoracoabdominal aortic surgery and thoracic endovascular repair.

    PubMed

    Jafarzadeh, Fatemeh; Bashir, Mohamad; Yan, Tristan; Harrington, Deborah; Field, Mark L; Kuduvalli, Manoj; Oo, Aung; Desmond, Michael

    2014-06-01

    Paraplegia is a complication that may occur following surgery or endovascular stenting of thoracic and thoracoabdominal aortic pathology. Measuring transcranial motor evoked potentials (tcMEPs) has been shown to provide a reliable measure of spinal cord function during such procedures allowing interventions to protect cord function. In the spirit of sharing experience and eliminating the learning curve for others, this manuscript describes our experience of setting up a service for tcMEP monitoring as well as the documents and algorithms for measuring, recording and acting on the patient data, the so-called 'MEP Pathway'. Recording and interpretation of tcMEP during thoracoabdominal aortic intervention requires training of staff and close team working in the operating theatre and postoperative intensive care unit. Providing consistent, reliable, specific and sensitive information on spinal cord function and its safe and effective use to alter patient outcomes requires a protocol. The MEP pathway was developed by medical and paramedical staff at our institution based on clinical experience and literature reviews over a 1-year period (2012-2013). The tcMEP pathway comprises six documents that guide staff in: (a) assessing suitability of patients, (b) setting up hardware, (c) preparing algorithms for management, (d) documenting intervention (left heart bypass, cardiopulmonary bypass or endovascular stenting) as well as (e) documenting postoperative intensive care processes. The tcMEP pathway acts as a guide for safe introduction and use of tcMEPs in thoracoabdominal aortic interventions. tcMEP-led guidance of intraoperative and postoperative management in thoracic aortic surgery is an important adjunct in caring for this patient group. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  20. Effects of vertebral column distraction on transcranial electrical stimulation-motor evoked potential and histology of the spinal cord in a porcine model.

    PubMed

    Yang, Jae Hyuk; Suh, Seung Woo; Modi, Hitesh N; Ramani, Easwar T; Hong, Jae Young; Hwang, Jin Ho; Jung, Woon Yong

    2013-05-01

    Spinal cord injury can occur following surgical procedures for correction of scoliosis and kyphosis, as these procedures produce lengthening of the vertebral column. The objective of this study was to cause spinal cord injury by vertebral column distraction and evaluate the histological changes in the spinal cord in relationship to the pattern of recovery from the spinal cord injury. Global osteotomy of all three spinal columns was performed on the ninth thoracic vertebra of sixteen pigs. The osteotomized vertebra was distracted until transcranial electrical stimulation-motor evoked potential (TES-MEP) signals disappeared or decreased by >80% compared with the baseline amplitude; this was defined as spinal cord injury. The distraction distance at which spinal cord injury occurred was measured, the distraction was released, and the TES-MEP recovery pattern was observed. A wake-up test was performed, two days of observations were made, and histological changes were evaluated in relationship to the recovery pattern. Spinal cord injury developed at a distraction distance of 20.2 ± 4.7 mm, equivalent to 3.6% of the thoracolumbar spinal length, and the distraction distance was correlated with the thoracolumbar spinal length (r = 0.632, p = 0.009). No animals exhibited complete recovery according to TES-MEP testing, eleven exhibited incomplete recovery, and five exhibited no recovery. During the two days of observation, all eleven animals with incomplete recovery showed positive responses to sensory and motor tests, whereas none of the five animals with no recovery had positive responses. On histological evaluation, three animals that exhibited no recovery all showed complete severance of nerve fibers (axotomy), whereas six animals that exhibited incomplete recovery all showed partial white-matter injury. Parallel distraction of approximately 3.6% of the thoracolumbar length after global osteotomy resulted in spinal cord injury and histological evidence of spinal cord

  1. [Intraoperative electrophysiological monitoring with evoked potentials].

    PubMed

    Nitzschke, R; Hansen-Algenstaedt, N; Regelsberger, J; Goetz, A E; Goepfert, M S

    2012-04-01

    During the last 30 years intraoperative electrophysiological monitoring (IOEM) has gained increasing importance in monitoring the function of neuronal structures and the intraoperative detection of impending new neurological deficits. The use of IOEM could reduce the incidence of postoperative neurological deficits after various surgical procedures. Motor evoked potentials (MEP) seem to be superior to other methods for many indications regarding monitoring of the central nervous system. During the application of IOEM general anesthesia should be provided by total intravenous anesthesia with propofol with an emphasis on a continuous high opioid dosage. When intraoperative MEP or electromyography guidance is planned, muscle relaxation must be either completely omitted or maintained in a titrated dose range in a steady state. The IOEM can be performed by surgeons, neurologists and neurophysiologists or increasingly more by anesthesiologists. However, to guarantee a safe application and interpretation, sufficient knowledge of the effects of the surgical procedure and pharmacological and physiological influences on the neurophysiological findings are indispensable.

  2. Hypothyroidism Affects Olfactory Evoked Potentials

    PubMed Central

    Świdziński, Teodor; Czerniejewska-Wolska, Hanna; Wiskirska-Woźnica, Bożena; Owecki, Maciej; Głowacka, Maria Danuta; Frankowska, Anna; Łącka, Katarzyna; Glapiński, Mariusz; Maciejewska-Szaniec, Zofia; Świdziński, Piotr

    2016-01-01

    Background. Objective electrophysiological methods for investigations of the organ of smell consist in recordings of olfactory cortex responses to specific, time restricted odor stimuli. In hypothyroidism have impaired sense of smell. Material and Methods. Two groups: control of 31 healthy subjects and study group of 21 with hypothyroidism. The inclusion criterion for the study group was the TSH range from 3.54 to 110 μIU/mL. Aim. Assessment of the latency time of evoked responses from the olfactory nerve N1 and the trigeminal nerve N5 using two smells of mint and anise in hypothyroidism. Results. The smell perception in subjective olfactory tests was normal in 85% of the hypothyroid group. Differences were noticed in the objective tests. The detailed intergroup analysis of latency times of recorded cortical responses PN5 and PN1 performed by means between the groups of patients with overt clinical hypothyroidism versus subclinical hypothyroidism demonstrated a significant difference (p < 0.05) whereas no such differences were found between the control group versus subclinical hypothyroidism group (p > 0.05). Conclusion. We can conclude that registration of cortex potentials at irritation of olfactory and trigeminal nerves offers possibilities for using this method as an objective indicator of hypothyroidism severity and prognostic process factor. PMID:27656655

  3. Hypothyroidism Affects Olfactory Evoked Potentials.

    PubMed

    Świdziński, Teodor; Linkowska-Świdzińska, Kamila; Czerniejewska-Wolska, Hanna; Wiskirska-Woźnica, Bożena; Owecki, Maciej; Głowacka, Maria Danuta; Frankowska, Anna; Łącka, Katarzyna; Glapiński, Mariusz; Maciejewska-Szaniec, Zofia; Świdziński, Piotr

    Background. Objective electrophysiological methods for investigations of the organ of smell consist in recordings of olfactory cortex responses to specific, time restricted odor stimuli. In hypothyroidism have impaired sense of smell. Material and Methods. Two groups: control of 31 healthy subjects and study group of 21 with hypothyroidism. The inclusion criterion for the study group was the TSH range from 3.54 to 110 μIU/mL. Aim. Assessment of the latency time of evoked responses from the olfactory nerve N1 and the trigeminal nerve N5 using two smells of mint and anise in hypothyroidism. Results. The smell perception in subjective olfactory tests was normal in 85% of the hypothyroid group. Differences were noticed in the objective tests. The detailed intergroup analysis of latency times of recorded cortical responses PN5 and PN1 performed by means between the groups of patients with overt clinical hypothyroidism versus subclinical hypothyroidism demonstrated a significant difference (p < 0.05) whereas no such differences were found between the control group versus subclinical hypothyroidism group (p > 0.05). Conclusion. We can conclude that registration of cortex potentials at irritation of olfactory and trigeminal nerves offers possibilities for using this method as an objective indicator of hypothyroidism severity and prognostic process factor.

  4. [The visual evoked potentials in diabetic retinopathy].

    PubMed

    Costache, Doina; Damian, Carmen; Iancău, Maria

    2004-01-01

    The recording of Visual Evoked Potential alterations at the patients with diabetic retinopathy. It was performed the Visual Evoked Potential recordings at 24 patients with diabetic retinopathy in different stages of evolution, with or without complications. The type of Visual Evoked Potential recording was pattern reversal with vertical bars. We followed the diagram alterations in correlation with the evolution stages of diabetic retinopathy and the visual parameter alterations. In all cases we recorded alteration of the Visual Evoked Potential. In nonproliferative diabetic retinopathy was noticed the delay of P100 wave with inconstant presence of the N75 and N135 waves. In proliferative diabetic retinopathy and its complications the alterations of the tract were important. The gradual alteration of the Visual Evoked Potential tract at the patients with diabetic retinopathy represents a prognosis of the disease.

  5. [Evoked somatosensory plexus and cervical evoked potentials in cervicobrachialgia].

    PubMed

    Rossi, L; Ubiali, E; Merli, R; Rottoli, M R

    1983-01-01

    The authors study the sensitive potential evoked from point of Erb and from cervical spine in C6-C7, obtained by stimulation of median nerve in a control group (normals) and in a greater group of 40 cases from patients affected by radiculopathie with or without discal protrusion and by myelopathie spondiloartrosic. The date supply significant informations and are (obicurred in analytique) analyzed with accuracy.

  6. The effect of sevoflurane on myogenic motor-evoked potentials induced by single and paired transcranial electrical stimulation of the motor cortex during nitrous oxide/ketamine/fentanyl anesthesia.

    PubMed

    Kawaguchi, M; Inoue, S; Kakimoto, M; Kitaguchi, K; Furuya, H; Morimoto, T; Sakaki, T

    1998-07-01

    To overcome anesthetic-induced depression of myogenic motor-evoked potentials (MEPs), several techniques of stimulation using paired pulses or trains of pulses are used. This study investigated the effect of sevoflurane on myogenic MEPs induced by single and paired transcranial electrical stimulation of the motor cortex. Nine patients undergoing elective spinal surgery were anesthetized with fentanyl-N2O-ketamine. Partial neuromuscular blockade (single-twitch height 15% of baseline) was maintained with vecuronium. Single and paired (interstimulus interval 2 milliseconds) electrical stimuli were delivered to the scalp, and compound muscle action potentials were recorded from the left and right tibialis anterior muscles. In all patients, baseline MEPs were recorded from both the left and right anterior tibialis muscles (in a total of 18 legs). During the administration of 0.25 MAC and 0.5 MAC sevoflurane, MEPs induced by stimulation with a single pulse could be recorded in 12 of 18 and 4 of 18 legs, respectively, and MEP amplitude was significantly reduced to 48% and 4% of the control value, respectively. During the administration of 0.75 MAC sevoflurane, MEPs following single-pulse stimulation could not be recorded in any legs. The success rate of MEP recording during the administration of sevoflurane was greater after paired stimulation than after single stimulation, and percentage MEP amplitude (percentage of the control value after single stimulation but before sevoflurane) after paired stimulation was significantly higher than after single stimulation before and during the administration of 0.25 MAC and 0.5 MAC sevoflurane. The success rate of MEP recording and MEP amplitude after paired stimulation decreased in a dose-dependent manner during the administration of sevoflurane. These results suggest that although facilitation by the second stimulus was considerable, paired stimuli are still not sufficient to overcome the depressant effects of sevoflurane in

  7. Intraoperative monitoring of somatosensory (SSEPs) and transcranial electric motor-evoked potentials (tce-MEPs) during surgical correction of neuromuscular scoliosis in patients with central or peripheral nervous system diseases.

    PubMed

    Pastorelli, F; Di Silvestre, M; Vommaro, F; Maredi, E; Morigi, A; Bacchin, M R; Bonarelli, S; Plasmati, R; Michelucci, R; Greggi, T

    2015-11-01

    Combined intraoperative monitoring (IOM) of transcranial electric motor-evoked potentials (tce-MEPs) and somatosensory-evoked potentials (SSEPs) is safe and effective for spinal cord monitoring during scoliosis surgery. However, the literature data regarding the reliability of spinal cord monitoring in patients with neuromuscular scoliosis are conflicting and need to be confirmed. We reviewed IOM records of 40 consecutive patients with neuromuscular scoliosis related to central nervous system (CNS) (29 pts) or peripheral nervous system (PNS) (11 patients) diseases, who underwent posterior fusion with instrumentation surgery for spinal deformity. Multimodalitary IOM with SSEPs and tce-MEPs was performed. Spinal cord monitoring using at least one modality was attempted in 38/40 (95 %) patients. No false-negative results were present in either group, but a relatively high incidence of false-positive cases (4/29, 13.8 %) was noted in the CNS group. Two patients in the CNS group and one patient in the PNS group presented transient postoperative motor deficits (true positive), related to surgical manoeuvres in two cases and to malposition in the other one. Multimodalitary IOM is safe and effective to detect impending spinal cord and peripheral nerves dysfunction in neuromuscular scoliosis surgery. However, the interpretation of neurophysiological data may be challenging in such patients, and the rate of false-positive results is high when pre-operatory motor deficits are severe.

  8. Pneumatic evoked potential. Sensory or auditive potential?

    PubMed

    Condé, S; Créac'h, C; Brun, X; Moreau, R; Convers, P; Peyron, R

    2013-06-01

    In this study, evoked potentials (EPs) to a pneumatic, innocuous, and calibrated stimulation of the skin were recorded in 22 volunteers. Air-puff stimuli were delivered through a home-made device (INSA de Lyon, Laboratoire Ampère, CHU de Saint-Étienne, France) synchronized with an EEG recording (Micromed(®)). A reproducible EP was recorded in 18 out of 22 subjects (82% of cases) with a mean latency of about 120-130ms, and maximal amplitude at Cz. This EP actually consisted of two components, an auditory and a somatosensory one. Indeed, it was significantly decreased in amplitude, but did not disappear, when the noise generated by the air-puff was masked. We also verified that a stimulation close to the skin but not perceived by the subject was not associated with any EP. Conduction velocity between hand and shoulder was calculated around 25m/s. This preliminary study demonstrates that pneumatic EPs can be recorded in normal volunteers. Copyright © 2013. Published by Elsevier SAS.

  9. Further experience with distal aortic perfusion and motor-evoked potential monitoring in the management of extent I-III thoracoabdominal aortic anuerysms.

    PubMed

    Lancaster, Robert T; Conrad, Mark F; Patel, Virendra I; Cambria, Matthew R; Ergul, Emel A; Cambria, Richard P

    2013-08-01

    Prior studies indicated improved early mortality and paraplegia rates in a small cohort of patients with type I-III thoracoabdominal aortic aneurysms (TAAs) treated with atriofemoral bypass (AFB) and motor-evoked potentials (MEVPs) when compared with a propensity-matched cohort of patients treated with the clamp and sew (CS) method, wherein epidural cooling was the principal spinal cord protective adjunct. The use of AFB/MEVP increases the complexity of TAA repair and in this study, we address whether the early benefits will be sustained when this is applied to a general population with type I-III TAAs. Consecutive patients undergoing repair of nonruptured Crawford extent I-III TAAs from 1/1987 to 12/2011 were identified. Patients were stratified according to operative approach (AFB/MEVP vs CS). Endpoints included long-term survival, and the composite outcome of perioperative death and paraplegia. A multivariate, risk-adjusted model was then created to determine if operative approach independently influenced outcome. There were 485 patients (CS = 385 [79%]; AFB/MEVP = 100 [21%]). The cohorts differed in that the AFB/MEVP group was younger (65.8 ± 12.5 years vs 70.9 ± 9.7 years; P < .001), had more extent I/II aneurysms (66% vs 50.1%; P = .005), and had more chronic dissections (30.3% vs 18.9%; P = .018). Operative variables differed in that the AFB/MEVP cohort had longer operative times (434 ± 112 minutes vs 324 ± 98 minutes; P < .001) and higher blood turnover (6028 ± 3473 mL vs 3581 ± 3111 mL; P < .0001). There was no difference in the rate of intraoperative death (AFB/MEVP = 1.0% vs CS = 0.5%; P = .50), length of intensive care unit stay (AFB/MEVP = 9.6 ± 8.6 days vs CS = 9.5 ± 12.3 days; P = .95) or hospital length of stay (AFB/MEVP = 19.9 ± 12.6 days vs CS = 21.6 ± 23.5 days; P = .49). The composite perioperative death and paraplegia rate was lower in the AFB/MEVP cohort (7% vs 19%; P = .004). The multivariate model for predictors of the composite

  10. Efferent and afferent evoked potentials in patients with adrenomyeloneuropathy.

    PubMed

    Matsumoto, Hideyuki; Hanajima, Ritsuko; Terao, Yasuo; Hamada, Masashi; Yugeta, Akihiro; Shirota, Yuichiro; Yuasa, Kaoru; Sato, Fumio; Matsukawa, Takashi; Takahashi, Yuji; Goto, Jun; Tsuji, Shoji; Ugawa, Yoshikazu

    2010-02-01

    This paper investigates efferent and afferent conductions of the central nervous system by various evoked potentials in patients with adrenomyeloneuropathy (AMN). Ten pure AMN patients without cerebral involvement were studied. Motor evoked potentials (MEPs), somatosensory evoked potentials (SEPs), auditory brainstem response (ABR), and pattern reversal full-field visual evoked potentials (VEPs) were recorded. For MEP recording, single-pulse or double-pulse magnetic brainstem stimulation (BST) was also performed. Abnormal MEP was observed in all ten patients, abnormal SEP in all ten, abnormal ABR in nine, and abnormal VEP in only one. Brainstem latency was measured in three of the seven patients with central motor conduction time (CMCT) prolongation. The cortical-brainstem conduction time was severely prolonged along the normal or mildly delayed brainstem-cervical conduction time in those three patients. The pattern of normal VEP and abnormal MEP, SEP, ABR is a clinically useful electrophysiological feature for the diagnosis. BST techniques are helpful to detect, functionally, intracranial corticospinal tract involvement, probably demyelination, in pure AMN patients. 2009 Elsevier B.V. All rights reserved.

  11. Short latency visual evoked potentials in man.

    PubMed

    Pratt, H; Bleich, N; Berliner, E

    1982-07-01

    Contrary to auditory and somatosensory evoked potentials, surface recorded visual evoked potentials which arise in subcortical neural elements have rarely been described. Considerable disagreement exists between the reports in the literature on such visual potentials. In this study, flash stimuli were used to evoke the potentials which were recorded from the skin overlying the infra-orbital ridge, outer canthus, middle of the forehead, vertex, mastoid ipsilateral to the stimulated eye and inion, using a non-cephalic reference. The potentials were amplified in a band which was chosen to omit slow retinal and cortical potentials, and to enhance activity which might include compound neural activity. Potentials were recorded from 9 subjects (13 eyes), and for each one the effects of eye position and stimulus intensity were studied. The results indicate that the series of components recorded within the first 100 msec following photic stimulation were volume-conducted activity generated by a subset of the visual system which is activated by luminosity changes. The generators of the first 4 or 5 components seem to be situated within the retina, the subsequent components seem to be generated in the optic nerve or tracts, and the later components may be thalamo-cortical in origin. These potentials may complement pattern evoked potentials in a more accurate definition of sites of lesions along the visual pathway.

  12. [Evoked potentials and post-traumatic evolution].

    PubMed

    Guérit, J-M

    2005-06-01

    Visual, somatosensory, and brainstem auditory evoked potentials provide functional quantitative assessment of the cerebral cortex and brainstem. Their contribution at the acute stage of coma concerns diagnosis, prognosis, and follow-up. Four patterns are observed in traumatic coma: pattern 1=dysfunction of the cerebral cortex, brainstem integrity: good prognosis in more than 80% of cases; pattern 2=midbrain dysfunction: prognosis depends on both the reversibility of midbrain dysfunction and the extent of associated axonal lesions in the hemispheric white matter; pattern 3=pontine dysfunction due to transtentorial herniation: ominous prognosis, this pattern must be early detected by continuous monitoring; pattern 4=brain death: we currently use evoked potentials at the only brain-death confirmatory test, even in sedated patients. The contribution of evoked potentials in vegetative or minimally responsive states concerns the identification of these patients whose state is determined by midbrain dysfunction and the evaluation of persisting cognitive abilities in individual cases.

  13. Experimental studies on spinal cord function using evoked action potentials.

    PubMed

    Soeda, S; Satomi, K; Hirabayashi, K

    1990-01-01

    Experiments were carried out on cats to determine the use of conductive evoked spinal cord action potentials in diagnosing motor function of the spinal cord. Direct stimulation from the dura produced three negative wave potentials, N1, N2 and N3. The intraspinal pathway of N2 and N3 was the dorsal column. The pathways of N1, determined by dorsal and ventral epidural recording, were the dorsilateral funicle and the extrapyramidal tracts. A collision experiment between potential N1 and pyramidal tract action potential did not reflect the function of the tract as the amplitude of the action potential was too small. Nevertheless, it is considered that conductive evoked spinal cord action potentials could become a valuable method of assessing spinal cord function as they reflect the function of the extrapyramidal tracts, as well as of the dorsilateral funicle and the dorsal column.

  14. Evoked potentials in monitoring multiple sclerosis.

    PubMed

    Leocani, L; Medaglini, S; Comi, G

    2000-01-01

    The usefulness of evoked potentials (EPs) in the diagnosis of multiple sclerosis is limited by its relatively low sensitivity to subclinical lesions. However, they are still a good tool to assess the integrity of afferent and efferent pathways and to quantify the severity of white matter involvement. Transversal and longitudinal studies have demonstrated good correlation between EP abnormalities and disability, suggesting that multimodal evoked potentials could be useful in monitoring the disease evolution in single patients and as surrogate end points in clinical trials.

  15. Laser evoked potentials in carpal tunnel syndrome.

    PubMed

    de Tommaso, Marina; Libro, Giuseppe; Difruscolo, Olimpia; Sardaro, Michele; Serpino, Claudia; Calabrese, Rita; Vecchio, Eleonora; Livrea, Paolo

    2009-02-01

    The aim of this study was to evaluate the function of Adelta fibers at the hand level in patients with clinical symptoms of Carpal Tunnel Syndrome (CTS) using CO(2) laser evoked potentials (LEPs), in light of the intensity and distribution of sensory symptoms and pain. Thirty-four CTS outpatients (62 hands) were compared to 23 sex- and age-matched control subjects (46 hands). The periungueal skin of the first, second, third and fifth fingers, and the dorsum of the hands were stimulated in random order. The latency and amplitude of the N2, P2 and N1 components were evaluated with respect to the Nerve Conduction Study (NCS) data, clinical scales, pain intensity and glove-like symptoms distribution. The amplitude of the N2-P2 complex was significantly reduced in CTS hands compared to normal hands after stimulation of the second and third fingers, even in patients with mild nerve conduction impairment. No significant fifth finger LEP abnormalities were found in patients with glove-like distribution symptoms. The N2-P2 amplitude at the second and third fingers was positively correlated with the severity of sensory symptoms. The involvement of median nerve Adelta fibers in CTS seems to be an early phenomenon, which concurs with the impairment of large motor and sensory afferents and is linked to the severity of the disease. The finding of reduced sensory symptoms in patients with severe thin afferents damage, may suggest a slight expression of central sensitisation phenomena in the advanced stage of CTS syndrome.

  16. Recording and assessment of evoked potentials with electrode arrays.

    PubMed

    Miljković, N; Malešević, N; Kojić, V; Bijelić, G; Keller, T; Popović, D B

    2015-09-01

    In order to optimize procedure for the assessment of evoked potentials and to provide visualization of the flow of action potentials along the motor systems, we introduced array electrodes for stimulation and recording and developed software for the analysis of the recordings. The system uses a stimulator connected to an electrode array for the generation of evoked potentials, an electrode array connected to the amplifier, A/D converter and computer for the recording of evoked potentials, and a dedicated software application. The method has been tested for the assessment of the H-reflex on the triceps surae muscle in six healthy humans. The electrode array with 16 pads was positioned over the posterior aspect of the thigh, while the recording electrode array with 16 pads was positioned over the triceps surae muscle. The stimulator activated all the pads of the stimulation electrode array asynchronously, while the signals were recorded continuously at all the recording sites. The results are topography maps (spatial distribution of evoked potentials) and matrices (spatial visualization of nerve excitability). The software allows the automatic selection of the lowest stimulation intensity to achieve maximal H-reflex amplitude and selection of the recording/stimulation pads according to predefined criteria. The analysis of results shows that the method provides rich information compared with the conventional recording of the H-reflex with regard the spatial distribution.

  17. [Evoked potentials in multiple sclerosis: progress or stagnation?].

    PubMed

    Zakrzewska-Pniewska, Beata

    2010-01-01

    Evoked potentials (EPs): visual (VEP), short latency somatosensory (SSEP), brainstem auditory (BAEP) and motor evoked potentials (MEP) can provide objective evidence of central nervous system (CNS) abnormalities that complement the clinical and radiological findings in establishing the diagnosis of multiple sclerosis (MS). The EPs studies may also improve the sensitivity of MS diagnosis. Abnormal EPs can provide evidence for pathology to satisfy the diagnostic criteria of lesions disseminated in space in the absence of clinical findings and for a relapse in patient with new symptoms but no changes on clinical examination. Since magnetic resonance imaging (MRI) plays a critical role in the current diagnostic criteria of MS, it is important to consider the relationship between EPs and MRI. Evoked potentials provide neurophysiological information about CNS functional abnormalities, while MRI provide anatomical localisation of CNS lesions. VEPs are even more sensitive than MRI in detecting acute and old pre-chiasmatic optic nerve lesions. The revised diagnostic criteria for MS include the provision for an abnormal VEP to serve as a diagnostic factor. Rarely, patients with spinal cord pathology may have an abnormal SEP or MEP without an observed lesions on MRI. Combining multimodality evoked potentials and MRI results in the greatest diagnostic yield. More widespread use of multimodality EPs in combination with MRI might lead to better outcome measurement in clinical trials as well as in open therapeutic approach. Thought EPs have some limitations, they remain an important factor in the diagnosis and clinical management of MS patients.

  18. [Effect of sleep deprivation on visual evoked potentials and brain stem auditory evoked potentials in epileptics].

    PubMed

    Urumova, L T; Kovalenko, G A; Tsunikov, A I; Sumskiĭ, L I

    1984-01-01

    The article reports on the first study of the evoked activity of the brain in epileptic patients (n = 20) following sleep deprivation. An analysis of the data obtained has revealed a tendency to the shortening of the peak latent intervals of visual evoked potentials in the range of 100-200 mu sec and the V component and the interpeak interval III-V of evoked auditory trunk potentials in patients with temporal epilepsy. The phenomenon may indicate the elimination of stabilizing control involving the specific conductive pathways and, possibly, an accelerated conduction of a specific sensor signal.

  19. Evoked potentials and head injury. 2. Clinical applications.

    PubMed

    Rappaport, M; Hopkins, H K; Hall, K; Belleza, T

    1981-10-01

    The method of rating abnormality of evoked brain potential patterns and assessing the extent and severity of cortical and subcortical brain dysfunction in head injury patients described in Part I is applied in a clinical context. Evoked potential abnormality (EPA) scores are found to be significantly correlated both with admission and outcome disability approximately one year after head injury. Correlations increase with the increase in the number of sensory modalities tested. Correlations between EPA scores and clinical disability (measured by the Disability Rating Scale) decrease with time after injury. Significant correlations, however, persist for about 60 days after onset of injury. It was found that EP pattern abnormalities can reflect specific sensory (and at times motor) deficits in noncommunicative patients and thereby contribute significantly to early treatment and rehabilitation planning.

  20. Early visual evoked potentials in callosal agenesis.

    PubMed

    Barr, Melodie S; Hamm, Jeff P; Kirk, Ian J; Corballis, Michael C

    2005-11-01

    Three participants with callosal agenesis and 12 neurologically normal participants were tested on a simple reaction time task, with visual evoked potentials collected using a high-density 128-channel system. Independent-components analyses were performed on the averaged visual evoked potentials to isolate the components of interest. Contrary to previous research with acallosals, evidence of ipsilateral activation was present in all 3 participants. Although ipsilateral visual components were present in all 4 unilateral conditions in the 2 related acallosal participants, in the 3rd, these were present only in the crossed visual field-hand conditions and not in the uncrossed conditions. Suggestions are made as to why these results differ from earlier findings and as to the neural mechanisms facilitating this ipsilateral activation.

  1. A primer on motion visual evoked potentials.

    PubMed

    Heinrich, Sven P

    2007-03-01

    Motion visual evoked potentials (motion VEPs) have been used since the late 1960s to investigate the properties of human visual motion processing, and continue to be a popular tool with a possible future in clinical diagnosis. This review first provides a synopsis of the characteristics of motion VEPs and then summarizes important methodological aspects. A subsequent overview illustrates how motion VEPs have been applied to study basic functions of human motion processing and shows perspectives for their use as a diagnostic tool.

  2. Laser and somatosensory evoked potentials in amyotrophic lateral sclerosis.

    PubMed

    Isak, Baris; Tankisi, Hatice; Johnsen, Birger; Pugdahl, Kirsten; Finnerup, Nanna Brix; Fuglsang-Frederiksen, Anders

    2016-10-01

    Mild involvement of sensory nerves has been reported in previous studies in ALS patients. In this study, we assessed sensory pathways in ALS patients using laser evoked potentials (LEPs) and somatosensory evoked potentials (SSEPs). We recruited 18 ALS patients and 31 healthy subjects. Neodymium-doped yttrium aluminium perovskite (Nd:YAP)-laser was used to evoke LEPs in upper (UE) and lower (LE) extremities. N1 and N2P2 potentials were obtained from contralateral insular cortex (T3 or T4) and vertex (Cz), respectively. Median SSEPs were recorded from C3' or C4' and tibial SSEPs from Cz'. Compared to controls, ALS patients had longer N2 and P2 latencies, and smaller N2P2 amplitudes in both UE- and LE-LEPs (p<0.05), and longer latencies for median and tibial SSEPs (p<0.05). LEPs and SSEPs were abnormal in 72.2% and 56.6% patients, respectively. Cortical potentials showed that A-beta or A-delta sensory fibres, or both, were impaired in more than half of the ALS patients. The findings support that ALS is a multi-systemic disorder involving, although to a lesser degree, other systems than the motor. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  3. Evoked potentials in immobilized cats to a combination of clicks with painful electrocutaneous stimuli

    NASA Technical Reports Server (NTRS)

    Gilinskiy, M. A.; Korsakov, I. A.

    1979-01-01

    Averaged evoked potentials in the auditory, somatosensory, and motor cortical zones, as well as in the mesencephalic reticular formation were recorded in acute experiments on nonanesthetized, immobilized cats. Omission of the painful stimulus after a number of pairings resulted in the appearance of a delayed evoked potential, often resembling the late phases of the response to the painful stimulus. The characteristics of this response are discussed in comparison with conditioned changes of the sensory potential amplitudes.

  4. Contact heat evoked potentials in normal subjects.

    PubMed

    Chen, I-An; Hung, Steven Wu; Chen, Yu-Hsien; Lim, Siew-Na; Tsai, Yu-Tai; Hsiao, Cheng-Lun; Hsieh, Hsiang-Yao; Wu, Tony

    2006-09-01

    Laser-evoked potentials are widely used to investigate nociceptive pathways. The newly developed contact heat stimulator for evoking brain response has the advantages of obtaining reliable scalp potentials and absence of cutaneous lesions. This study aimed to identify the most appropriate stimulation site with consistent cortical responses, and to correlate several parameters of the contact heat evoked potentials (CHEPs) with age, gender, and body height in normal subjects. CHEPs were recorded at Cz with a contact heat stimulator (Medoc, Israel) in 35 normal controls. The subjects were asked to keep eyes open and remain alert. The baseline temperature was 32 degrees C, and stimulation peak heat intensity of 51 degrees C was applied to five body sites: bilateral forearm, right dorsum hand, right peroneal area, and right dorsum foot. Reproducible CHEPs were recorded more frequently when stimulated at volar forearm (62.5%) than at the lower limbs (around 40%). The first negative peak latency (N1) was 370.1 +/- 20.3 ms, first positive peak latency (P1) was 502.4 +/- 33.0 ms, and peak to peak amplitude was 10.2 +/- 4.9 microV with stimulation of the forearm. Perceived pain intensity was not correlated with the presence or amplitude of CHEPs. No gender or inter-side differences were observed for N1 latency and N1-P1 amplitude. Also, no correlation was noted between N1 and age or body height. These results support future clinical access of CHEPs as a diagnostic tool.

  5. [Cognitive evoked potentials. Perspectives for mismatch negativity].

    PubMed

    Gurtubay, I G

    2009-01-01

    The techniques of cognitive evoked potentials are considered long and technically complex, which is why their use in clinical practice is not very widespread in spite of their potential utility. Recent advances in registering and analysis, together with improvement of the software managing these signals, have appreciably reduced these problems. Mismatch negativity stands out as the most promising of all the cognitive potentials due to its special characteristics regarding its generation requisites and its proven clinical utility. The fact that it can be generated without care requirements makes it especially useful for evaluating subjects with a low level of consciousness; it serves for predicting when they will emerge from a coma, amongst other uses. The incorporation of this technique into the arsenal of neurophysiological techniques for evaluating the state of these subjects will bring a substantial improvement in the evaluation of cases whose management in clinical practice is extremely complex.

  6. Long Latency Auditory Evoked Potentials during Meditation.

    PubMed

    Telles, Shirley; Deepeshwar, Singh; Naveen, Kalkuni Visweswaraiah; Pailoor, Subramanya

    2015-10-01

    The auditory sensory pathway has been studied in meditators, using midlatency and short latency auditory evoked potentials. The present study evaluated long latency auditory evoked potentials (LLAEPs) during meditation. Sixty male participants, aged between 18 and 31 years (group mean±SD, 20.5±3.8 years), were assessed in 4 mental states based on descriptions in the traditional texts. They were (a) random thinking, (b) nonmeditative focusing, (c) meditative focusing, and (d) meditation. The order of the sessions was randomly assigned. The LLAEP components studied were P1 (40-60 ms), N1 (75-115 ms), P2 (120-180 ms), and N2 (180-280 ms). For each component, the peak amplitude and peak latency were measured from the prestimulus baseline. There was significant decrease in the peak latency of the P2 component during and after meditation (P<.001; analysis of variance and post hoc analysis with Bonferroni adjustment). The P1, P2, and N2 components showed a significant decrease in peak amplitudes during random thinking (P<.01; P<.001; P<.01, respectively) and nonmeditative focused thinking (P<.01; P<.01; P<.05, respectively). The results suggest that meditation facilitates the processing of information in the auditory association cortex, whereas the number of neurons recruited was smaller in random thinking and non-meditative focused thinking, at the level of the secondary auditory cortex, auditory association cortex and anterior cingulate cortex.

  7. Effects of exercise on visual evoked potentials.

    PubMed

    Ozmerdivenli, Recep; Bulut, Serpil; Bayar, Hale; Karacabey, Kursat; Ciloglu, Figen; Peker, Ismail; Tan, Uner

    2005-07-01

    The aim of this study was to investigate the effects of acute or habitual exercise on visual evoked potentials (VEP). The study group consisted of 9 female and 7 male volleyball players and the control group contained 9 female and 7 male students who were not involved in any sportive activity. The N75, P100, and N145 latency and amplitudes were measured before and after exercise. Intragroup comparison was made to evaluate the acute effects and intergroup comparison for the chronic effects of exercise. Significant differences were noted between athletes and the sedentary subjects in terms of pre-exercise left-N145 latencies and amplitudes and left -P100 amplitudes. Right-eye N145 latencies of inactive female subjects obtained before and after exercise were also statistically different. The results suggest that acute and habitual exercise affects the VEP responses independent from the body temperature and other physiological parameters. Small sized pre-exercise P100 amplitudes in the athletes can be attributed to the effect of rapid visual-activity-demanding sports on the central nervous system. Visual evoked potentials maybe used as neurophysiological criteria in defining the performance of an athlete.

  8. [Personality dimensions and cerebral evoked potential].

    PubMed

    Camposano, S; Alvarez, C; Lolas, F

    1994-12-01

    Eysenck's personality theory postulates 3 orthogonal dimensions of personality: extraversion (E), neuroticism (N) and psychoticism (P), predicting conductual and physiological predispositions to suffer mental illness. Biological bases of Eysenck's personality traits have been documented electrophysiologically. Psychoticism, the latest described dimension, is controverted, since there is some evidence of common factors with the other two. In order to assess the relation between Eysenck's dimensions and sensorial reactivity and information encoding processes we studied 20 healthy young subjects (mean age 28.5 years) with flash visual cortical evoked potentials (VEP, 3 intensities, peak to peak amplitude of III, IV-V-VI, VII components), and auditory cognitive evoked potentials (odd ball paradigm, P300 latency). There was a positive correlation between N and P dimensions (Spearman, r = 0.52), between N and VEP amplitude at high intensity (r = 0.58) and a negative correlation between E and P300 latency (r = 0.58). In short we found that P is not an independent dimension, but is related to sensorial reactivity. E dimension was related to encoding processes supporting Eysenck's observations about memory and learning differences.

  9. New perspectives on vestibular evoked myogenic potentials.

    PubMed

    Rosengren, Sally M; Kingma, Herman

    2013-02-01

    Although the vestibular evoked myogenic potential (VEMP) measured from the cervical muscles (cVEMP, cervical VEMP) is well described and has documented clinical utility, its analogue recorded from the extraocular muscles (oVEMP, ocular VEMP) has been described only recently and is currently emerging as an additional test of otolith function. This review will, therefore, summarize recent developments in VEMP research with a focus on the oVEMP. Recent studies suggest that the oVEMP is produced by otolith afferents in the superior vestibular nerve division, whereas the cVEMP evoked by sound is thought to be an inferior vestibular nerve reflex. Correspondingly, the oVEMP correlates better with caloric and subjective visual vertical tests than sound-cVEMPs. cVEMPs are more complicated than often thought, as shown by the presence of crossed responses and conflicting results of recent vibration studies. Altered inner ear mechanics produced by the vestibular diseases superior semicircular canal dehiscence and Ménière's disease lead to changes in the preferred frequency of the oVEMP and cVEMP. The oVEMP provides complementary diagnostic information to the cVEMP and is likely to be a useful addition to the diagnostic test battery in neuro-otology.

  10. Cervical vestibular evoked myogenic potentials in children.

    PubMed

    Pereira, Alcione Botelho; Silva, Gabriela Souza de Melo; Assunção, Aída Regina Monteiro; Atherino, Ciriaco Cristóvão Tavares; Volpe, Fernando Madalena; Felipe, Lilian

    2015-01-01

    Cervical vestibular evoked myogenic potential is a test used in neurotological examination. It verifies the integrity of vestibular function through a muscular response evoked by an acoustic stimulation which activates the saccular macula. Normal standards in adults have been established, however, there are few published data on the normal responses in children. To establish normal standards for vestibular myogenic responses in children without neurotological complaints. This study's design is a cohort with cross-sectional analysis. The sample consisted of 30 subjects, 15 females (50%) and 15 males (50%). The age of the subjects ranged between 8 and 13 years, with a mean of 10.2 (± 1.7). P1 peak showed an average latency of 17.26 (± 1.78)ms and a mean amplitude of 49.34 (± 23.07)μV, and the N2 peak showed an average latency of 24.78 (± 2.18)ms and mean amplitude of 66.23 (± 36.18)μV. P1-N2 mean amplitude was 115.6 (± 55.7)μV. There were no statistically significant differences when comparing by gender or by laterality. We established normal values of cervical myogenic vestibular responses in children between 8 and 13 years without neurotological complaints. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  11. Non-invasive modulation of somatosensory evoked potentials by the application of static magnetic fields over the primary and supplementary motor cortices.

    PubMed

    Kirimoto, Hikari; Asao, Akihiko; Tamaki, Hiroyuki; Onishi, Hideaki

    2016-10-04

    This study was performed to investigate the possibility of non-invasive modulation of SEPs by the application of transcranial static magnetic field stimulation (tSMS) over the primary motor cortex (M1) and supplementary motor cortex (SMA), and to measure the strength of the NdFeB magnetic field by using a gaussmeter. An NdFeB magnet or a non-magnetic stainless steel cylinder (for sham stimulation) was settled on the scalp over M1 and SMA of 14 subjects for periods of 15 min. SEPs following right median nerve stimulation were recorded before and immediately after, 5 min after, and 10 min after tSMS from sites C3' and F3. Amplitudes of the N33 component of SEPs at C3' significantly decreased immediately after tSMS over M1 by up to 20%. However, tSMS over the SMA did not affect the amplitude of any of the SEP components. At a distance of 2-3 cm (rough depth of the cortex), magnetic field strength was in the range of 110-190 mT. Our results that tSMS over M1 can reduce the amplitude of SEPs are consistent with those of low-frequency repeated TMS and cathodal tDCS studies. Therefore, tSMS could be a useful tool for modulating cortical somatosensory processing.

  12. Non-invasive modulation of somatosensory evoked potentials by the application of static magnetic fields over the primary and supplementary motor cortices

    PubMed Central

    Kirimoto, Hikari; Asao, Akihiko; Tamaki, Hiroyuki; Onishi, Hideaki

    2016-01-01

    This study was performed to investigate the possibility of non-invasive modulation of SEPs by the application of transcranial static magnetic field stimulation (tSMS) over the primary motor cortex (M1) and supplementary motor cortex (SMA), and to measure the strength of the NdFeB magnetic field by using a gaussmeter. An NdFeB magnet or a non-magnetic stainless steel cylinder (for sham stimulation) was settled on the scalp over M1 and SMA of 14 subjects for periods of 15 min. SEPs following right median nerve stimulation were recorded before and immediately after, 5 min after, and 10 min after tSMS from sites C3′ and F3. Amplitudes of the N33 component of SEPs at C3′ significantly decreased immediately after tSMS over M1 by up to 20%. However, tSMS over the SMA did not affect the amplitude of any of the SEP components. At a distance of 2–3 cm (rough depth of the cortex), magnetic field strength was in the range of 110–190 mT. Our results that tSMS over M1 can reduce the amplitude of SEPs are consistent with those of low-frequency repeated TMS and cathodal tDCS studies. Therefore, tSMS could be a useful tool for modulating cortical somatosensory processing. PMID:27698365

  13. Resting Heart Rate and Auditory Evoked Potential

    PubMed Central

    Fiuza Regaçone, Simone; Baptista de Lima, Daiane Damaris; Engrácia Valenti, Vitor; Figueiredo Frizzo, Ana Cláudia

    2015-01-01

    The objective of this study was to evaluate the association between rest heart rate (HR) and the components of the auditory evoked-related potentials (ERPs) at rest in women. We investigated 21 healthy female university students between 18 and 24 years old. We performed complete audiological evaluation and measurement of heart rate for 10 minutes at rest (heart rate monitor Polar RS800CX) and performed ERPs analysis (discrepancy in frequency and duration). There was a moderate negative correlation of the N1 and P3a with rest HR and a strong positive correlation of the P2 and N2 components with rest HR. Larger components of the ERP are associated with higher rest HR. PMID:26504838

  14. Visual evoked potentials in rubber factory workers.

    PubMed

    Tandon, O P; Kumar, V

    1997-01-01

    Pattern reversal visual evoked potentials (pVEP) were studied in 39 male rubber factory workers in the age range of 18-55 years and 20 control subjects (aged 18-46 years) not exposed to the rubber factory environment. Results revealed that 20 (51%) rubber factory workers had abnormal latencies of wave P1 (dominant component of pVEP) as per accepted criteria of 99% tolerance limit set for the control group (i.e. any value above mean +3 SD of control was considered abnormal). The section-wise per cent distribution of abnormalities was vulcanization (83%), tubing (75%), calendering (60%), loading (38%) and mixing (14%). This study provides electrophysiological evidence that rubber factory environments affect the conduction processes in optical pathways from their origin in the retina to striate cortex. However, this study has its limitations in not identifying the specific chemical(s) causing these changes in VEP.

  15. Auditory evoked potentials in senescent forgetfulness.

    PubMed

    Loring, D W; Levin, H S; Papanicolaou, A C; Larrabee, G J; Eisenberg, H M

    1984-10-01

    Two evoked potential (EP) techniques and the selective reminding test were employed to investigate an apparently benign forgetfulness in seven elderly subjects and seven age-matched elderly subjects with normal memory. EPs were also recorded in a group of seven young adults. Latency of the P3 component, which has been demonstrated to increase in primary degenerative dementia, displayed the normal age-related variation in both elderly groups, but did not differ between the forgetful subjects and the elderly controls. Further, no difference in the recovery cycle of the EP, as measured in a two tone stimulation paradigm, was present between forgetful and elderly control groups. Reexamination of memory after nearly a year disclosed no evidence of deterioration in either elderly group. These findings suggest that senescent forgetfulness, as defined herein, may be a nonprogressive memory disorder.

  16. Visual evoked potentials through night vision goggles.

    PubMed

    Rabin, J

    1994-04-01

    Night vision goggles (NVG's) have widespread use in military and civilian environments. NVG's amplify ambient illumination making performance possible when there is insufficient illumination for normal vision. While visual performance through NVG's is commonly assessed by measuring threshold functions such as visual acuity, few attempts have been made to assess vision through NVG's at suprathreshold levels of stimulation. Such information would be useful to better understand vision through NVG's across a range of stimulus conditions. In this study visual evoked potentials (VEP's) were used to evaluate vision through NVG's across a range of stimulus contrasts. The amplitude and latency of the VEP varied linearly with log contrast. A comparison of VEP's recorded with and without NVG's was used to estimate contrast attenuation through the device. VEP's offer an objective, electrophysiological tool to assess visual performance through NVG's at both threshold and suprathreshold levels of visual stimulation.

  17. [Lissajous figures of the visual evoked potentials].

    PubMed

    Watanabe, Y; Watanabe, M; Takigawa, M

    1986-03-01

    The value of the visual evoked potential (VEP) technique for diagnosis of epilepsy is limited. Except for photosensitive epilepsies, the visual evoked potentials (VEPs) do not reveal more than a routine EEG. As one of the reasons of that, it is pointed out that a review of VEP literature reveals different "normal values" for peak latencies and amplitudes. Thus in this study, lissajous figures of VEPs (VEP-L) were attempted instead of the measurement of peak latencies and amplitudes of VEPs. Thirty six epileptic subjects (14 have partial seizures, 22 have generalized seizures) and 22 control subjects were investigated. Several EEGs to storoboscopic flashes were recorded from scalp electrodes placed at the frontal (Fz) and occipital (Oz) regions according to the 10-20 electrode system, using a right ear as nonreference with a EEG amplifier (Nihon Kohden ME-175 E) and a data recorder (TEAC R-60). Then the phasic relationships between the VEPs from the two areas were analyzed with a medical computer (Nohon Kohden ATAC-2300) and printed out as VEP-L. The results are summerized as follows: First, as time passes from 100 msec to 200 msec in the VEP-L, the epileptic patient group showed more right-roted types than that of the control group (p less than 0.01). Second, the VEP-L at the periods from 50 msec after photic stimulus, were classified into 5 types inspectively. The 5 types are the right-ascending type, the left-ascending type, the vertical type, the horizontal type, and the circular type.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Auditory Evoked Potentials from the Frog Eighth Nerve

    DTIC Science & Technology

    1989-09-01

    ACCESSION NO. Brooks AFB, TX 78235-5301 62202F 7757 01 85 11. TITLE (I nclude Security Classification) (U) Auditory Evoked Potentials from the Frog Eighth...identify by block number) S FIELD jGROUP SUB-GROUP F6 07 Auditory Evoked Potential Eighth Nerve Frog 06 10 19. ABSTRACT (Continue on reverse if necessary...and identify by block number) A method for recording evoked potentials from the eighth nerve of frogs using midline and lateral electrodes is described

  19. Chirp-modulated visual evoked potential as a generalization of steady state visual evoked potential.

    PubMed

    Tu, Tao; Xin, Yi; Gao, Xiaorong; Gao, Shangkai

    2012-02-01

    Visual evoked potentials (VEPs) are of great concern in cognitive and clinical neuroscience as well as in the recent research field of brain-computer interfaces (BCIs). In this study, a chirp-modulated stimulation was employed to serve as a novel type of visual stimulus. Based on our empirical study, the chirp stimuli visual evoked potential (Chirp-VEP) preserved frequency features of the chirp stimulus analogous to the steady state evoked potential (SSVEP), and therefore it can be regarded as a generalization of SSVEP. Specifically, we first investigated the characteristics of the Chirp-VEP in the time-frequency domain and the fractional domain via fractional Fourier transform. We also proposed a group delay technique to derive the apparent latency from Chirp-VEP. Results on EEG data showed that our approach outperformed the traditional SSVEP-based method in efficiency and ease of apparent latency estimation. For the recruited six subjects, the average apparent latencies ranged from 100 to 130 ms. Finally, we implemented a BCI system with six targets to validate the feasibility of Chirp-VEP as a potential candidate in the field of BCIs.

  20. Chirp-modulated visual evoked potential as a generalization of steady state visual evoked potential

    NASA Astrophysics Data System (ADS)

    Tu, Tao; Xin, Yi; Gao, Xiaorong; Gao, Shangkai

    2012-02-01

    Visual evoked potentials (VEPs) are of great concern in cognitive and clinical neuroscience as well as in the recent research field of brain-computer interfaces (BCIs). In this study, a chirp-modulated stimulation was employed to serve as a novel type of visual stimulus. Based on our empirical study, the chirp stimuli visual evoked potential (Chirp-VEP) preserved frequency features of the chirp stimulus analogous to the steady state evoked potential (SSVEP), and therefore it can be regarded as a generalization of SSVEP. Specifically, we first investigated the characteristics of the Chirp-VEP in the time-frequency domain and the fractional domain via fractional Fourier transform. We also proposed a group delay technique to derive the apparent latency from Chirp-VEP. Results on EEG data showed that our approach outperformed the traditional SSVEP-based method in efficiency and ease of apparent latency estimation. For the recruited six subjects, the average apparent latencies ranged from 100 to 130 ms. Finally, we implemented a BCI system with six targets to validate the feasibility of Chirp-VEP as a potential candidate in the field of BCIs.

  1. Evoked potentials during cardiac and major vascular operations.

    PubMed

    Stecker, Mark M

    2004-06-01

    Somatosensory evoked potentials are widely used in spine surgery to prevent injury to the spinal cord. However, their application in cardiac and major vascular surgery is largely unappreciated. This paper will review the unique stresses placed on peripheral nerves, spinal cord, and brain during these operations. In addition, the potential benefits of peri-operative somatosensory evoked potentials monitoring are described in detail.

  2. Neonatal somatosensory evoked potentials persist during hypothermia.

    PubMed

    Nevalainen, Päivi; Lauronen, Leena; Metsäranta, Marjo; Lönnqvist, Tuula; Ahtola, Eero; Vanhatalo, Sampsa

    2017-06-01

    Treatment with therapeutic hypothermia has challenged the use of amplitude-integrated electroencephalography in predicting outcomes after perinatal asphyxia. In this study, we assessed the feasibility and gain of somatosensory evoked potentials (SEP) during hypothermia. This retrospective study comprised neonates from 35 + 6 to 42 + 2 gestational weeks and treated for asphyxia or hypoxic-ischaemic encephalopathy at Helsinki University Hospital between 14 February 2007 and 23 December 2009. This period was partly before the introduction of routine therapeutic hypothermia, which enabled us to include normothermic neonates who would these days receive hypothermia treatment. We analysed SEPs from 47 asphyxiated neonates and compared the results between 23 normothermic and 24 hypothermic neonates. Our data showed that hypothermia led to SEP latencies lengthening by a few milliseconds, but the essential gain for predicting outcomes by SEPs was preserved during hypothermia. Of the 24 hypothermic neonates, bilaterally absent SEPs were associated with poor outcome in 2/2 neonates, normal SEPs were associated with good outcomes in 13/15 neonates and 5/7 neonates with unilaterally absent or grossly delayed SEPs had a poor outcome. Our findings indicated that SEPs were a reliable tool for evaluating the somatosensory system in asphyxiated neonates in both normothermic and hypothermic conditions. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  3. [Auditory evoked potentials: basics and clinical applications].

    PubMed

    Radeloff, A; Cebulla, M; Shehata-Dieler, W

    2014-09-01

    Auditory evoked potentials (AEPs) are elicited at various levels of the auditory system following acoustic stimulation. Electrocochleography is a technique for recording AEPs of the inner ear. The recording is performed by means of a needle electrode placed on the promontory or non-invasive with tympanic membrane or ear canal electrodes. Clinically, electrocochleography is used for the diagnosis of auditory neuropathy spectrum disorder (ANSD) and endolymphatic hydrops. According to their latencies, AEPs of the central auditory pathway are subdivided into early, middle and late (cortical) AEPs. These AEPs are recorded via surface scalp electrodes. Normally, the larger EEG masks AEPs. For unmasking the AEP, several techniques are applied. Early AEPs or auditory brainstem responses (ABR) are the most widely used AEPs for functional evaluation of the auditory pathway. In contrast to otoacoustic emissions, early AEPs can detect ANSD. Thus, they are more suitable for hearing screening in newborns. For this purpose automated procedures are implemented. © Georg Thieme Verlag KG Stuttgart · New York.

  4. Auditory evoked potential measurements with cetaceans

    NASA Astrophysics Data System (ADS)

    Mann, David; Cook, Mandy; Bauer, Gordon; Fellner, Wendi; Wells, Randy

    2005-04-01

    Auditory evoked potentials (AEPs) allow researchers to measure the hearing abilities of animals that would be difficult or impossible to train for behavioral measurements of hearing. The hearing abilities of live-stranded cetaceans and wild dolphins can only be made with AEP techniques. In these situations, time with the animal is often restricted to an hour or less, and there is often little control over the acoustic environment in which the tests are performed. AEP measurements may be made while the animals are in air or in shallow pools. For cetaceans in air, sounds are typically presented with a suction cup jawphone. For cetaceans in water, sounds may be presented in a direct field (with the transducer located at some distance from the test subject) or with a jawphone. In each of these situations it is important to understand how thresholds derived from AEP measurements compare with behavioral hearing measurements. Examples of AEP measurements from wild and live-stranded cetaceans are presented to illustrate their usefulness and the constraints under which these measurements must be made. AEP measurements from bottlenose dolphins in air and in water are also compared with their behavioral audiograms.

  5. Effects of aging on laser evoked potentials.

    PubMed

    Creac'H, Christelle; Bertholon, Alexandre; Convers, Philippe; Garcia-Larrea, Luis; Peyron, Roland

    2015-05-01

    Aging has been reported to reduce the amplitude of laser evoked potentials. However, it is unknown whether this effect depends on the length of the sensory fibers. This is an important issue, because most painful neuropathies are length-dependent. We conducted a study of 40 healthy subjects, half of whom were older than age 50 years. Nociceptive stimuli were delivered to the feet and thighs using a CO2 laser stimulator. Detection and pain perception thresholds did not correlate with age. Latencies of N1, N2, and P2 correlated positively with age on the feet but not on the thighs, whereas the amplitude of N2-P2 decreased with age for both areas. The effects of aging on latencies may reflect a distal loss of peripheral inputs and a length-dependent de-synchronization of the ascending nociceptive volley. Additional changes in peripheral and central processes may explain the diffuse decrease of N2-P2 amplitudes observed with aging. © 2014 Wiley Periodicals, Inc.

  6. Auditory evoked potential measurements in elasmobranchs

    NASA Astrophysics Data System (ADS)

    Casper, Brandon; Mann, David

    2005-04-01

    Auditory evoked potentials (AEP) were first used to examine hearing in elasmobranchs by Corwin and Bullock in the late 1970s and early 1980s, marking the first time AEPs had been measured in fishes. Results of these experiments identified the regions of the ear and brain in which sound is processed, though no actual hearing thresholds were measured. Those initial experiments provided the ground work for future AEP experiments to measure fish hearing abilities in a manner that is much faster and more convenient than classical conditioning. Data will be presented on recent experiments in which AEPs were used to measure the hearing thresholds of two species of elasmobranchs: the nurse shark, Ginglymostoma cirratum, and the yellow stingray, Urobatis jamaicencis. Audiograms were analyzed and compared to previously published audiograms obtained using classical conditioning with results indicating that hearing thresholds were similar for the two methods. These data suggest that AEP testing is a viable option when measuring hearing in elasmobranchs and can increase the speed in which future hearing measurements can be obtained.

  7. Caloric vestibular stimulation modulates nociceptive evoked potentials

    PubMed Central

    Ferrè, Elisa Raffaella; Haggard, Patrick; Bottini, Gabriella; Iannetti, Gian Domenico

    2016-01-01

    Vestibular stimulation has been reported to alleviate central pain. Clinical and physiological studies confirm pervasive interactions between vestibular signals and somatosensory circuits, including nociception. However, the neural mechanisms underlying vestibular-induced analgesia remain unclear, and previous clinical studies cannot rule out explanations based on alternative, non-specific effects such as distraction or placebo. To investigate how vestibular inputs influence nociception, we combined caloric vestibular stimulation (CVS) with psychophysical and electrocortical responses elicited by nociceptive-specific laser stimulation in humans (laser-evoked potentials, LEPs). Cold-water CVS applied to the left ear resulted in significantly lower subjective pain intensity for experimental laser pain to the left hand immediately after CVS, relative both to before CVS, and to 1 hour after CVS. This transient reduction in pain perception was associated with reduced amplitude of all LEP components, including the early N1 wave reflecting the first arrival of nociceptive input to primary somatosensory cortex. We conclude that cold left ear CVS elicits a modulation of both nociceptive processing and pain perception. The analgesic effect induced by CVS could be mediated by either subcortical gating of the ascending nociceptive input, or by direct modulation of the primary somatosensory cortex. PMID:26282602

  8. Caloric vestibular stimulation modulates nociceptive evoked potentials.

    PubMed

    Ferrè, Elisa Raffaella; Haggard, Patrick; Bottini, Gabriella; Iannetti, Gian Domenico

    2015-12-01

    Vestibular stimulation has been reported to alleviate central pain. Clinical and physiological studies confirm pervasive interactions between vestibular signals and somatosensory circuits, including nociception. However, the neural mechanisms underlying vestibular-induced analgesia remain unclear, and previous clinical studies cannot rule out explanations based on alternative, non-specific effects such as distraction or placebo. To investigate how vestibular inputs influence nociception, we combined caloric vestibular stimulation (CVS) with psychophysical and electrocortical responses elicited by nociceptive-specific laser stimulation in humans (laser-evoked potentials, LEPs). Cold water CVS applied to the left ear resulted in significantly lower subjective pain intensity for experimental laser pain to the left hand immediately after CVS, relative both to before CVS and to 1 h after CVS. This transient reduction in pain perception was associated with reduced amplitude of all LEP components, including the early N1 wave reflecting the first arrival of nociceptive input to primary somatosensory cortex. We conclude that cold left ear CVS elicits a modulation of both nociceptive processing and pain perception. The analgesic effect induced by CVS could be mediated either by subcortical gating of the ascending nociceptive input, or by direct modulation of the primary somatosensory cortex.

  9. Clinical aspects of the visually evoked potential.

    PubMed Central

    Weinstein, G W

    1977-01-01

    The visually evoked potential (VEP) was studied in normal and abnormal human subjects, and in Rhesus monkeys with central, paracentral, and peripheral photocoagulation lesions. A relatively simple protocol for clinical VEP testing is described. The monkeys showed similar VEP responses but these were smaller in amplitude than those obtained from human subjects. Central, but not paracentral or peripheral retinal lesions were associated with VEP abnormalities. For both monkey and human subjects, some variability of responses between normal and subjects was noted. Generally, there are differences in VEP responses obtained from the affected eye of abnormal subjects who had one eye which could serve as a control, as compared to responses from the normal eye. In these subjects as well as in subjects with two abnormal eyes, computer analysis of digitized VEP data from 10 Hz stimulus responses was performed. Fourier transformation analyses showed abnormalities which could be detected easily by evaluating the pattern of the amplitudes of the fundamental and first three harmonics. With this technique, it was possible to group correctly normal VEP's with eyes with normal visual acuity (greater than or equal to 20/30 or 0.67), and abnormal VEP's with eyes with poor visual acuity (less than 20/30 or 0.67) in 72% of cases. Analysis of the data obtained with 1 Hz and 10 Hz stimulation suggests that the components of the VEP related to visual acuity occur within the first 60-100 msec of the response, corresponding to the primary evoked response of Chiganek. The second, smaller wave of the response complex to 10 Hz flash stimuli corresponds to the primary evoked response, and is closely related to visual acuity. This was further supported in another series in which the digitized data was filtered around the stimulating frequency. It was possible to recognize visually this VEP waveform and subjectively interpret the record correctly in 85% of eyes with regard to visual acuity

  10. Visual evoked potentials in the horse.

    PubMed

    Ström, L; Ekesten, B

    2016-06-21

    Electrical potentials generated in the central nervous system in response to brief visual stimuli, flash visual evoked potentials (FVEPs), can be recorded non-invasively over the occipital cortex. FVEPs are used clinically in human medicine and also experimentally in a number of animal species, but the method has not yet been evaluated in the horse. The method would potentially allow the ophthalmologist and equine clinician to evaluate visual impairment caused by disorders affecting post-retinal visual pathways. The aim was to establish a method for recording of FVEPs in horses in a clinical setting and to evaluate the waveform morphology in the normal horse. Ten horses were sedated with a continuous detomidine infusion. Responses were recorded from electrodes placed on the scalp. Several positions were evaluated to determine suitable electrode placement. Flash electroretinograms (FERGs) were recorded simultaneously. To evaluate potential contamination of the FVEP from retinal potentials, a retrobulbar nerve block was performed in two horses and transection of the optic nerve was performed in one horse as a terminal procedure. A series of positive (P) and negative (N) peaks in response to light stimuli was recorded in all horses. Reproducible wavelets with mean times-to-peaks of 26 (N1), 55 (P2), 141 (N2) and 216 ms (P4) were seen in all horses in all recordings. Reproducible results were obtained when the active electrode was placed in the midline rostral to the nuchal crest. Recording at lateral positions gave more variable results, possibly due to ear muscle artifacts. Averaging ≥100 responses reduced the impact of noise and artifacts. FVEPs were reproducible in the same horse during the same recording session and between sessions, but were more variable between horses. Retrobulbar nerve block caused a transient loss of the VEP whereas transection of the optic nerve caused an irreversible loss. We describe the waveform of the equine FVEP and our results show

  11. [Utilization of evoked potentials in intensive care units].

    PubMed

    Ferré, A; Lainez, E; Moreno, I

    2009-04-01

    Evoked Potentials (EP) are a neurophysiological tool that makes it possible for us to make an extensive study of the cerebral cortex, the brainstem and the spinal cord. Different techniques can be applied while performing the EPs, such as Visual Evoked Potentials (VEPs), Somatosensory Evoked Potentials (SSEPs), Long Latency Somatosensory Evoked Potentials (LLSEPs), Brainstem Auditory Evoked Potentials (BAEPs), Middle Latency Auditory Evoked Potentials (MLAEPs), Long Latency Auditory Evoked Potentials (LLAEP) and Mismatch Negativity (MMN). The combination of the different techniques of Evoked Potentials (EP) allows us to make a neurofunctional evaluation of comatose patients in the Intensive Care Units (ICU). It is also a useful tool in the diagnosis of the origin of coma, to confirm brain death, and as an evolutive prognosis value of the different central nervous system diseases (SNC). There are also studies that propose using EPs as a monitoring tool of the SNC. We present an up-dated review on the principal aspects of EP neuromonitoring in Intensive Care Unit (ICU) patients.

  12. [Experimental visual evoked potentials. Interstimuli interval and cortical excitability].

    PubMed

    Díaz Calavia, E; Fernández del Moral, R; Dawid-Milner, S; Jiménez Vargas, J

    1989-01-01

    The excitability of the visual system was studied in ten adult chronic cats. Visual evoked potentials were recorded, using decreasing interstimulus intervals. A decrease of the excitability of the visual system is observed when interstimulus intervals are less than 800 milliseconds. Clinical applications with regard to visual evoked potential recording on comatose patients are suggested.

  13. Variance of vestibular-evoked myogenic potentials.

    PubMed

    Ochi, K; Ohashi, T; Nishino, H

    2001-03-01

    Vestibular-evoked myogenic potential (VEMP) has been thought to originate from sacculus. The variance of this potential and the effectiveness of the adjustments of pInII amplitudes using average muscle tonus of ipsilateral sternocleidomastoid muscle were evaluated. In addition, clinical application of VEMP was examined in patients with acoustic tumors (ATs) and vestibular neurolabyrinthitis (VNL). Prospective evaluation of the VEMP in 18 normal volunteers and 6 patients. Variance and left-right difference of each parameter, including pI latency, nII latency, pInII amplitude, and threshold, was analyzed. Input-output function of pInII amplitude was evaluated. Average muscle tonus was calculated in 20 ears and applied for adjustment of pInII amplitude. Sensitivity of each parameter of VEMP was examined in 3 patients with ATs and 3 patients with VNL. VEMP was present in all 36 ears of 18 control subjects. Thresholds of VEMP for normal subjects were 80 to 95 dB normal hearing level (nHL). The muscle tonus affected pInII amplitude significantly; however, no statistically significant improvement was observed in test-retest investigation after adjustment using muscle tonus. The threshold of the affected side was elevated compared with the non-affected side in all patients with ATs, whereas 2 of 3 patients showed normal pInII-ratio. One patient with VNL presented normal VEMP, whereas 2 patients presented no VEMP to the highest stimulus intensity. Interaural difference of thresholds might be the most useful parameters. Adjustment using average muscle tonus is not necessary when the subject is able to get sufficient muscle tonus.

  14. [Brainstem auditory evoked potentials and somatosensory evoked potentials in Chiari malformation].

    PubMed

    Moncho, Dulce; Poca, María A; Minoves, Teresa; Ferré, Alejandro; Rahnama, Kimia; Sahuquillo, Juan

    2013-06-16

    Introduccion. La malformacion de Chiari (MC) incluye una serie de anomalias congenitas que tienen como comun denominador la ectopia de las amigdalas del cerebelo por debajo del foramen magno, lo que puede condicionar fenomenos compresivos del troncoencefalo, la medula espinal alta y los nervios craneales, alterando las respuestas de los potenciales evocados auditivos del tronco cerebral (PEATC) y de los potenciales evocados somatosensoriales (PESS). Sin embargo, las indicaciones de ambas exploraciones en las MC han sido motivo de estudio en un numero limitado de publicaciones, centradas en series cortas y heterogeneas de pacientes. Objetivo. Revisar los hallazgos de los PEATC y los PESS en los estudios publicados en pacientes con MC tipo 1 (MC-1) o tipo 2 (MC-2), y su indicacion en el diagnostico, tratamiento y seguimiento, especialmente en la MC-1. Desarrollo. Es un estudio de revision realizado mediante analisis de los estudios publicados en Medline desde 1966, localizados mediante PubMed, utilizando combinaciones de las palabras clave 'Chiari malformation', 'Arnold-Chiari malformation', 'Chiari type 1 malformation', 'Arnold-Chiari type 1 malformation', 'evoked potentials', 'brainstem auditory evoked potentials' y 'somatosensory evoked potentials', asi como informacion de pacientes con MC-1 valorados en los servicios de neurocirugia y neurofisiologia clinica del Hospital Universitari Vall d'Hebron. Conclusiones. Los hallazgos mas comunes de los PESS son la reduccion en la amplitud cortical para el nervio tibial posterior, la reduccion o ausencia del potencial cervical del nervio mediano y el aumento del intervalo N13-N20. En el caso de los PEATC, los hallazgos mas frecuentes descritos son el aumento del intervalo I-V y la alteracion periferica o coclear.

  15. Pattern visual evoked potentials for identifying malingering.

    PubMed

    Sun, I-Ting; Lee, Jong-Jer; Huang, Hsiu-Mei; Kuo, Hsi-Kung

    2015-06-01

    To investigate the efficacy of pattern visual evoked potentials (VEPs) in evaluating objective visual acuity (VA) and discriminating malingerers. Two hundred and forty-nine eyes of 249 patients aged 20-65 years were included. There were 147 eyes with macular diseases (group 1) and 102 eyes with optic nerve diseases (group 2). Amplitudes and latencies were analyzed and correlated with best-corrected visual acuity by a regression analysis. We found the best-correlated mode of pattern VEP, determined the relations, and then calculated the pattern VEP-estimated VA (PVEP-VA) of all 249 eyes, another 30 malingering eyes, 13 eyes with macular diseases, and 17 eyes with optic nerve diseases, and used a receiver operating characteristic (ROC) curve to determine a cutoff for acceptable variance between PVEP-VA and subjective VA to discriminate malingerers. The best correlation was between the amplitude of 50' checkerboard size (Amp50') and VA in every group. Significant correlation was between Amp50' and VA, where p < 0.0001 in group 1 and p = 0.020 in group 2. A logarithmic curve best fitted the correlation in the regression analysis, where y = 1.731 - 1.569x (R(2) = 0.611, p < 0.0001) in group 1 and y = 2.413 - 2.169x (R(2) = 0.531, p < 0.0001) in group 2 [x: log(Amp50'), y: PVEP-VA (logMAR)]. By using the relations and ROC curve, we determined a variance value of 0.4041 (logMAR) with 100% sensitivity and 94.0% specificity in group 1 and 0.3658 with 70.6% sensitivity and 50.5% specificity in group 2 to discriminate malingerers. The pattern VEP amplitude of 50' checkerboard size was useful to assess VA and can be helpful in discriminating malingering from real disability.

  16. Aging effect on vestibular evoked myogenic potential.

    PubMed

    Su, Hsuan-Chao; Huang, Tsung-Wei; Young, Yi-Ho; Cheng, Po-Wen

    2004-11-01

    Vestibular evoked myogenic potential (VEMP) is applied to explore the integrity of sacculocollic reflex. Although tests to evaluate vestibular-ocular reflex pathway have shown that vestibular function is adversely affected by aging, VEMP, in this study, is used as a novel test to define how aging influences sacculocollic reflex pathway. Prospective study. Academic tertiary referral center. Eighty normal subjects, equally divided into four groups according to their age, were enrolled to this study. Group I included patients aged <20 years, Group II patient ages ranged from 21 to 40 years, Group III patients were 41 to 60 years, and Group IV included patients older than 60 years. Recordings of VEMP responses. The response rate and parameters of VEMP, including p13 latency, n23 latency, amplitude, and interaural difference ratio. The VEMP response rates from Groups I to IV was 98%, 98%, 90%, and 60%, respectively, disclosing a significant difference only between Group IV and other groups (p < 0.05). The amplitude was negatively correlated with age in contrast to the n23 latency, correlating positively with age; both reached a significant difference (p < 0.05). Although the p13 latency had a trend to prolong as age increased, no significant correlation existed (p < 0.06). Moreover, the interaural difference ratio was also not significantly correlated with age. As age increased over 60 years, the VEMP response rate decreased dramatically. While age increased, the VEMP amplitude decreased in comparison to n23 latency prolonged. These findings might suggest that aging could deteriorate the saccular and corresponding neural functions. When interpreting the VEMP parameters, it should be kept in mind that aging could affect VEMP responses. Based on this study, we suggest establishing different reference values according to different age groups when evaluating VEMP response in patients with vestibular diseases.

  17. A Bayesian approach to estimate evoked potentials.

    PubMed

    Sparacino, Giovanni; Milani, Stefano; Arslan, Edoardo; Cobelli, Claudio

    2002-06-01

    Several approaches, based on different assumptions and with various degree of theoretical sophistication and implementation complexity, have been developed for improving the measurement of evoked potentials (EP) performed by conventional averaging (CA). In many of these methods, one of the major challenges is the exploitation of a priori knowledge. In this paper, we present a new method where the 2nd-order statistical information on the background EEG and on the unknown EP, necessary for the optimal filtering of each sweep in a Bayesian estimation framework, is, respectively, estimated from pre-stimulus data and obtained through a multiple integration of a white noise process model. The latter model is flexible (i.e. it can be employed for a large class of EP) and simple enough to be easily identifiable from the post-stimulus data thanks to a smoothing criterion. The mean EP is determined as the weighted average of the filtered sweeps, where each weight is inversely proportional to the expected value of the norm of the correspondent filter error, a quantity determinable thanks to the employment of the Bayesian approach. The performance of the new approach is shown on both simulated and real auditory EP. A signal-to-noise ratio enhancement is obtained that can allow the (possibly automatic) identification of peak latencies and amplitudes with less sweeps than those required by CA. For cochlear EP, the method also allows the audiology investigator to gather new and clinically important information. The possibility of handling single-sweep analysis with further development of the method is also addressed.

  18. Evoked potentials and head injury. 1. Rating of evoked potential abnormality.

    PubMed

    Rappaport, M; Hall, K; Hopkins, H K; Belleza, T

    1981-10-01

    This paper describes a method for rating the degree of abnormality of auditory, visual and somatosensory evoked potential patterns in head injury (HI) patients. Criteria for judging degree of EP abnormality are presented that allow assessment of the extent and severity of subcortical and cortical dysfunction associated with traumatic brain damage. Interrater reliability data based upon blind ratings of normal and HI patients are presented and shown to be highly significant. Tables of normative values of peak latencies and amplitudes are given and illustrations of EP patterns of different degrees of abnormality are presented.

  19. Electroretinography and Visual Evoked Potentials in Childhood Brain Tumor Survivors.

    PubMed

    Pietilä, Sari; Lenko, Hanna L; Oja, Sakari; Koivisto, Anna-Maija; Pietilä, Timo; Mäkipernaa, Anne

    2016-07-01

    This population-based cross-sectional study evaluates the clinical value of electroretinography and visual evoked potentials in childhood brain tumor survivors. A flash electroretinography and a checkerboard reversal pattern visual evoked potential (or alternatively a flash visual evoked potential) were done for 51 survivors (age 3.8-28.7 years) after a mean follow-up time of 7.6 (1.5-15.1) years. Abnormal electroretinography was obtained in 1 case, bilaterally delayed abnormal visual evoked potentials in 22/51 (43%) cases. Nine of 25 patients with infratentorial tumor location, and altogether 12 out of 31 (39%) patients who did not have tumors involving the visual pathways, had abnormal visual evoked potentials. Abnormal electroretinographies are rarely observed, but abnormal visual evoked potentials are common even without evident anatomic lesions in the visual pathway. Bilateral changes suggest a general and possibly multifactorial toxic/adverse effect on the visual pathway. Electroretinography and visual evoked potential may have clinical and scientific value while evaluating long-term effects of childhood brain tumors and tumor treatment.

  20. Auditory evoked potentials and vestibular evoked myogenic potentials in evaluation of brainstem lesions in multiple sclerosis.

    PubMed

    Ivanković, Anita; Nesek Mađarić, Vesna; Starčević, Katarina; Krbot Skorić, Magdalena; Gabelić, Tereza; Adamec, Ivan; Habek, Mario

    2013-05-15

    The aim of this study was to determine the roles of magnetic resonance imaging (MRI), auditory evoked potentials (AEP) and vestibular evoked myogenic potentials (VEMP) in the evaluation of brainstem involvement in multiple sclerosis (MS). Altogether 32 patients with the diagnosis of MS participated in the study. The following data was collected from all patients: age, gender, Expanded Disability Status Scale (EDSS) score, brainstem functional system score (BSFS) (part of the EDSS evaluating brainstem symptomatology), and involvement of the brainstem on the brain MRI. AEP and ocular VEMP (oVEMP) and cervical VEMP (cVEMP) were studied in all patients. BSFS, MRI, AEP, oVEMP and cVEMP involvement of the brainstem was evident in 9 (28.1%), 14 (43.8%), 7 (21.9%), 12 (37.5%) and 10 (31.0%) patients, respectively. None of the tests used showed statistically significant advantage in the detection of brainstem lesions. When combining oVEMP and cVEMP 18 (56.3%) patients showed brainstem involvement. This combination showed brainstem involvement in greater percentage than BSFS or AEP, with statistical significance (p=0.035 and p=0.007, respectively). VEMP is a reliable method in detection of brainstem involvement in MS. It is comparable with MRI, but superior to clinical examination or AEP. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Monitoring somatosensory evoked potentials in spinal cord ischemia-reperfusion injury

    PubMed Central

    Ji, Yiming; Meng, Bin; Yuan, Chenxi; Yang, Huilin; Zou, Jun

    2013-01-01

    It remains unclear whether spinal cord ischemia-reperfusion injury caused by ischemia and other non-mechanical factors can be monitored by somatosensory evoked potentials. Therefore, we monitored spinal cord ischemia-reperfusion injury in rabbits using somatosensory evoked potential detection technology. The results showed that the somatosensory evoked potential latency was significantly prolonged and the amplitude significantly reduced until it disappeared during the period of spinal cord ischemia. After reperfusion for 30–180 minutes, the amplitude and latency began to gradually recover; at 360 minutes of reperfusion, the latency showed no significant difference compared with the pre-ischemic value, while the somatosensory evoked potential amplitude in-creased, and severe hindlimb motor dysfunctions were detected. Experimental findings suggest that changes in somatosensory evoked potential latency can reflect the degree of spinal cord ischemic injury, while the amplitude variations are indicators of the late spinal cord reperfusion injury, which provide evidence for the assessment of limb motor function and avoid iatrogenic spinal cord injury. PMID:25206629

  2. Effect of intrathecal baclofen on evoked pain perception: an evoked potentials and quantitative thermal testing study.

    PubMed

    Kumru, H; Kofler, M; Flores, M C; Portell, E; Robles, V; Leon, N; Vidal, J

    2013-08-01

    Somatic antinociceptive effects of baclofen have been demonstrated in animal models. We hypothesized that if enhanced thermal or pain sensitivity is produced by loss of gamma-aminobutyric acid (GABA)-ergic tone in the central nervous system, spinal administration of GABA agonists might be predicted to be effective in thermal and/or pain perception changes and pain-related evoked potentials in candidates for intrathecal baclofen (ITB) treatment. Eleven patients with severe spinal cord injury (SCI) who suffered from severe spasticity were evaluated during a 50-μg ITB bolus test. Warm and heat pain thresholds, evoked heat pain perception, and contact heat-evoked potentials (CHEPs) were determined above SCI level from the right and left sides. Nine age- and gender-matched healthy volunteers undergoing repeat testing without any placebo injection served as control group. In patients, heat pain perception threshold increased, and evoked pain perception and amplitude of CHEPs decreased significantly after ITB bolus application in comparison with baseline (p < 0.005), with no change in warm perception threshold. In controls, no significant changes were observed in repeat testing over time. Our findings indicate that ITB modulates heat pain perception threshold, evoked heat pain perception and heat pain-related evoked potentials without inducing warm perception threshold changes in SCI patients. This phenomenon should be taken into account in the clinical evaluation and management of pain in patients receiving baclofen. © 2012 European Federation of International Association for the Study of Pain Chapters.

  3. Flash visual evoked potentials in preterm infants.

    PubMed

    Feng, Jing-Jing; Wang, Wei-Ping; Guo, Shu-Juan; Liu, Zhi-Wei; Xu, Xiu

    2013-03-01

    To describe the development of flash visual evoked potentials (FVEPs) in preterm infants from 1 to 18 months and to determine if the maturation of FVEPs is similar to that of term infants. Longitudinal follow-up study. Twenty very low birth weight (VLBW) preterm infants, 42 low birth weight (LBW) preterm infants, and 41 term infants underwent FVEP recordings and neurodevelopmental examinations at 1, 3, 6, 9, 12, and 18 months of corrected and chronological ages. The FVEP recordings were carried out with the VikingQuest-IV neuroelectrophysiological device (VikingQuest, Nicolet, WI), and neurodevelopmental assessments were made by the Development Screen Test and Bayley Scales of Infant Development, Second Edition. At 1, 3, 6, and 9 months of age, neurodevelopment was measured with the Mental Index and Developmental Quotient. At 12 and 18 months, neurodevelopment was assessed using the Mental Developmental Index and Psychomotor Developmental Index. Two FVEP values were analyzed: the P2 amplitude (peak to peak from the preceding N2 wave) and the latency of the P2 wave. There was no significant difference for age-dependent decreased pattern of FVEP P2 latency between preterm infants and the control group. This pattern consisted of a rapid decrease in the first 6 months of life, a gradual decline from 6 to 12 months of age, and a steady reduction from 12 to 18 months of age. The P2 latencies were prolonged significantly at all 6 recorded times in the VLBW group compared with the controls and showed a delay in the LBW group at 1 and 3 months of corrected age. The maturation of P2 latency in LBW infants is similar to that of the controls at 3 months of corrected age, but the maturation of P2 latency in VLBW children remained delayed when compared with the controls until 18 months of corrected age. Although the FVEP development pattern of preterm infants was similar to that of healthy full-term infants, the former had deficits in visual electrophysiologic maturation

  4. Somatosensory Evoked Potential Findings in Ankylosing Spondylitis

    PubMed Central

    Cidem, Muharrem; Sahin, Zerrin; Aydin, Teoman; Aysal, Fikret

    2014-01-01

    Objective: Somatosensory evoked potential (SSEP) abnormalities were reported in patients with ankylosing spondylitis (AS). This study aimed to investigate SSEP abnormalities and its relation with clinical findings in AS patients. Materials and Methods: The study included 26 patients with AS and 17 age-matched health volunteers (Control for SSEP). Median nerve SSEP findings were normal in all AS cases. Results: However, delayed latency and/or very low amplitude of tibial nerve SSEP was found in 20 (76.9%) AS patients. There were significant correlations between tibial SSEP latency and disease duration (R=0.433 to 0.635). There was also an inverse correlation between tibial SSEP amplitude and disease duration (R=−0.429, p=0.047). Serum estradiol level, hip total bone mineral density, The Bath Ankylosing Spondylitis Functional Index (BASFI) score and Beck depression score were significantly lower in AS patients with SSEP abnormalities (37.3±10.8 pg/mL, 0.916±0.123 g/cm2, 35.0±27.9, 12.8±8.4, respectively) than in AS patients without SSEP abnormalities (53.7±12.3 pg/mL, 1.103±0.197 g/cm2, 64.8±15.5, 24.8±10.1, respectively). Conclusion: Significant inverse correlations between SSEP latencies and dehydroepiandrosterone sulphate (DHEAS) levels were found (R=−0.400 to −0.713). There were also significant inverse correlation between SSEP latencies and DHEAS/oestrogen index (R=−0.596 to −0.868), and between SSEP latencies and DHEAS/Progesterone index (R=−0.467 to −0.685). As a conclusion, this study indicates that tibial nerve SSEP abnormalities are common in patients with AS and there are significant correlations between clinical findings of AS and SSEP abnormalities. PMID:25610293

  5. Correlation between temperature and vibration thresholds and somatosensory evoked potentials.

    PubMed

    Meh, D; Denislic, M

    2000-01-01

    The psychophysically assessed thermal specific, thermal pain and vibration sensitivities were correlated to somatosensory evoked potentials in eighteen patients with definite multiple sclerosis. In the psychophysical tests, modality specific stimuli were used. Somatosensory potentials were electrically evoked. The abnormalities of both the temperature and the vibration sensitivity were to same extent related to the somatosensory evoked potentials. Dorsal columns-medial lemnisc and anterolateral-spinothalamic demyelinating lesions were presumed. The psychophysical tests supplement the clinical, laboratory, neuroradiologic and electrophysiological tests. These should be included in the battery of diagnostic tests in multiple sclerosis.

  6. Click- and chirp-evoked human compound action potentials.

    PubMed

    Chertoff, Mark; Lichtenhan, Jeffery; Willis, Marie

    2010-05-01

    In the experiments reported here, the amplitude and the latency of human compound action potentials (CAPs) evoked from a chirp stimulus are compared to those evoked from a traditional click stimulus. The chirp stimulus was created with a frequency sweep to compensate for basilar membrane traveling wave delay using the O-Chirp equations from Fobel and Dau [(2004). J. Acoust. Soc. Am. 116, 2213-2222] derived from otoacoustic emission data. Human cochlear traveling wave delay estimates were obtained from derived compound band action potentials provided by Eggermont [(1979). J. Acoust. Soc. Am. 65, 463-470]. CAPs were recorded from an electrode placed on the tympanic membrane (TM), and the acoustic signals were monitored with a probe tube microphone attached to the TM electrode. Results showed that the amplitude and latency of chirp-evoked N1 of the CAP differed from click-evoked CAPs in several regards. For the chirp-evoked CAP, the N1 amplitude was significantly larger than the click-evoked N1s. The latency-intensity function was significantly shallower for chirp-evoked CAPs as compared to click-evoked CAPs. This suggests that auditory nerve fibers respond with more unison to a chirp stimulus than to a click stimulus.

  7. Evoked response study tool: a portable, rugged system for single and multiple auditory evoked potential measurements.

    PubMed

    Finneran, James J

    2009-07-01

    Although the potential of using portable auditory evoked potential systems for field testing of stranded cetaceans has been long recognized, commercial systems for evoked potential measurements generally do not possess the bandwidth required for testing odontocete cetaceans and are not suitable for field use. As a result, there have been a number of efforts to develop portable evoked potential systems for field testing of cetaceans. This paper presents another such system, called the evoked response study tool (EVREST). EVREST is a Windows-based hardware/software system designed for calibrating sound stimuli and recording and analyzing transient and steady-state evoked potentials. The EVREST software features a graphical user interface, real-time analysis and visualization of recorded data, a variety of stimulus options, and a high level of automation. The system hardware is portable, rugged, battery-powered, and possesses a bandwidth that encompasses the audible range of echolocating odontocetes, making the system suitable for field testing of stranded or rehabilitating cetaceans.

  8. Magnetic stimulation of the human motor cortex evokes skin sympathetic nerve activity.

    PubMed

    Silber, D H; Sinoway, L I; Leuenberger, U A; Amassian, V E

    2000-01-01

    Single-pulse magnetic coil stimulation (Cadwell MES 10) over the cranium induces without pain an electric pulse in the underlying cerebral cortex. Stimulation over the motor cortex can elicit a muscle twitch. In 10 subjects, we tested whether motor cortical stimulation could also elicit skin sympathetic nerve activity (SSNA; n = 8) and muscle sympathetic nerve activity (MSNA; n = 5) in the peroneal nerve. Focal motor cortical stimulation predictably elicited bursts of SSNA but not MSNA; with successive stimuli, the SSNA responses did not readily extinguish (94% of discharges to the motor cortex evoked SSNA responses) and had predictable latencies [739 +/- 33 (SE) to 895 +/- 13 ms]. The SSNA responses were similar after stimulation of dominant and nondominant sides. Focal stimulation posterior to the motor cortex elicited extinguishable SSNA responses. In three of six subjects, anterior cortical stimulation evoked SSNA responses similar to those seen with motor cortex stimulation but without detectable movement; in the other subjects, anterior stimulation evoked less SSNA discharge than that seen with motor cortex stimulation. Contrasting with motor cortical stimulation, evoked SSNA responses were more readily extinguished with 1) peripheral stimulation that directly elicited forearm muscle activation accompanied by electromyograms similar to those with motor cortical stimulation; 2) auditory stimulation by the click of the energized coil when off the head; and 3) in preliminary experiments, finger afferent stimulation sufficient to cause tingling. Our findings are consistent with the hypothesis that motor cortex stimulation can cause activation of both alpha-motoneurons and SSNA.

  9. Brainstem Auditory Evoked Potential in HIV-Positive Adults

    PubMed Central

    Matas, Carla Gentile; Samelli, Alessandra Giannella; Angrisani, Rosanna Giaffredo; Magliaro, Fernanda Cristina Leite; Segurado, Aluísio C.

    2015-01-01

    Background To characterize the findings of brainstem auditory evoked potential in HIV-positive individuals exposed and not exposed to antiretroviral treatment. Material/Methods This research was a cross-sectional, observational, and descriptive study. Forty-five HIV-positive individuals (18 not exposed and 27 exposed to the antiretroviral treatment – research groups I and II, respectively – and 30 control group individuals) were assessed through brainstem auditory evoked potential. Results There were no significant between-group differences regarding wave latencies. A higher percentage of altered brainstem auditory evoked potential was observed in the HIV-positive groups when compared to the control group. The most common alteration was in the low brainstem. Conclusions HIV-positive individuals have a higher percentage of altered brainstem auditory evoked potential that suggests central auditory pathway impairment when compared to HIV-negative individuals. There was no significant difference between individuals exposed and not exposed to antiretroviral treatment. PMID:26485202

  10. Postural sway and brain potentials evoked by visual depth stimuli.

    PubMed

    Kiyota, Takeo; Fujiwara, Katsuo

    2008-07-01

    This study measured the postural sway and brain potentials evoked by a visual depth stimulus. Thirteen subjects maintained standing posture on a force platform, and were administered two types of depth stimuli, strong and weak. The latency and amplitude of evoked potentials as well as changes in center of foot pressure (CFP) and the electromyogram (EMG) were examined. CFP displacement was found to change according to stimulus intensity. In the occipital lobe, evoked potentials exhibited a triphasic peak, with the first positive peak at approximately 120 ms (P120), the first negative peak at approximately 160 ms (N200), and the second positive peak at approximately 260 ms (P250). Brain evoked potentials correlated with CFP displacement as well as the latency of onset of EMG response. Onset of EMG response was probably related to the P120 component, whereas CFP displacement was related to the P250 component.

  11. A Basis for Evoked Potential Assessment of Certain Visual Functions.

    DTIC Science & Technology

    1981-06-30

    Chromatic adaptation and steady-state evoked potentials. Vision Res., 1968, 8, 149-158. 6. Regan, D. Evoked potentials and sensation. Perception Psycho...D. Evidence for the existence of neural mechanisms selectively sensitive to the direction of movement in space. J. Physiol., 1973, 235, 17-29. 34a...Beverley, K.I. 1 Regan, D. Selective adaptation in stereoscopic depth perception. J. Phvsiol., 1973, 232, 40-41P. 35. Regan, D. & Beverley, K.I

  12. Sensory evoked potentials in Guillain-Barré polyneuropathy.

    PubMed Central

    Brown, W F; Feasby, T E

    1984-01-01

    In 11 patients with acute Guillain-Barré polyneuropathy examined within 2 weeks of the onset of the paralysis, sensory evoked potential techniques were able to demonstrate a proximal conduction delay between Erb's point and the cervical cord in 10 subjects; while sensory conduction distal to Erb's point was much more commonly normal in the early period. Sensory evoked potential techniques provide therefore a valuable way to demonstrate proximal conduction velocity slowing early in the course of this disease. PMID:6707675

  13. Brainstem auditory evoked potentials and middle latency auditory evoked potentials in young children.

    PubMed

    Luo, Jin Jun; Khurana, Divya S; Kothare, Sanjeev V

    2013-03-01

    Measurements of brainstem auditory evoked potentials (BAEP) and middle latency auditory evoked potentials (MLAEP) are readily available neurophysiologic assessments. The generators for BAEP are believed to involve the structures of cochlear nerve, cochlear nucleus, superior olive complex, dorsal and rostral pons, and lateral lemniscus. The generators for MLAEP are assumed to be located in the subcortical area and auditory cortex. BAEP are commonly used in evaluating children with autistic and hearing disorders. However, measurement of MLAEP is rarely performed in young children. To explore the feasibility of this procedure in young children, we retrospectively reviewed our neurophysiology databank and charts for a 3-year period to identify subjects who had both BAEP and MLAEP performed. Subjects with known or identifiable central nervous system abnormalities from the history, neurologic examination and neuroimaging studies were excluded. This cohort of 93 children up to 3 years of age was divided into 10 groups based on the age at testing (upper limits of: 1 week; 1, 2, 4, 6, 8, 10 and 12 months; 2 years; and 3 years of age). Evolution of peak latency, interpeak latency and amplitude of waveforms in BAEP and MLAEP were demonstrated. We concluded that measurement of BAEP and MLAEP is feasible in children, as early as the first few months of life. The combination of both MLAEP and BAEP may increase the diagnostic sensitivity of neurophysiologic assessment of the integrity or functional status of both the peripheral (acoustic nerve) and the central (brainstem, subcortical and cortical) auditory conduction systems in young children with developmental speech and language disorders. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. [The visual evoked potentials in open angle glaucoma].

    PubMed

    Damian, Carmen; Iancău, Maria; Costache, Doina

    2004-01-01

    The study purpose to analyse the variations of Visual Evoked Potentials on a group of patients with Open Angle Glaucoma. It was performed the Visual Evoked Potential recordings on a number of patients with Open Angle Glaucoma in different stages of evolutions. Some of the patients were monitored by the Visual Evoked Potentials recordings in a dynamic way, before and after the law pressure treatment. The type of Visual Evoked Potentials recording was pattern reversal with vertical bars. In incipient stage of Open Angle Glaucoma the alteration of the tract was minimal with inconstant presence of the N75 and N135 waves and just a few variation of the delay of P100. In advanced stages of Open Angle Glaucoma the alterations of the tract were important: the delay of P100 wave. In absolute stage the tract was null. The alterations of Visual Evoked Potentials tract was influenced by the different stages of evolution of Open Angle Glaucoma. The gradual alteration of the Visual Evoked Potential tract represents a prognosis of the disease.

  15. Motor tics evoked by striatal disinhibition in the rat

    PubMed Central

    Bronfeld, Maya; Yael, Dorin; Belelovsky, Katya; Bar-Gad, Izhar

    2013-01-01

    Motor tics are sudden, brief, repetitive movements that constitute the main symptom of Tourette syndrome (TS). Multiple lines of evidence suggest the involvement of the cortico-basal ganglia system, and in particular the basal ganglia input structure—the striatum in tic formation. The striatum receives somatotopically organized cortical projections and contains an internal GABAergic network of interneurons and projection neurons' collaterals. Disruption of local striatal GABAergic connectivity has been associated with TS and was found to induce abnormal movements in model animals. We have previously described the behavioral and neurophysiological characteristics of motor tics induced in monkeys by local striatal microinjections of the GABAA antagonist bicuculline. In the current study we explored the abnormal movements induced by a similar manipulation in freely moving rats. We targeted microinjections to different parts of the dorsal striatum, and examined the effects of this manipulation on the induced tic properties, such as latency, duration, and somatic localization. Tics induced by striatal disinhibition in monkeys and rats shared multiple properties: tics began within several minutes after microinjection, were expressed solely in the contralateral side, and waxed and waned around a mean inter-tic interval of 1–4 s. A clear somatotopic organization was observed only in rats, where injections to the anterior or posterior striatum led to tics in the forelimb or hindlimb areas, respectively. These results suggest that striatal disinhibition in the rat may be used to model motor tics such as observed in TS. Establishing this reliable and accessible animal model could facilitate the study of the neural mechanisms underlying motor tics, and the testing of potential therapies for tic disorders. PMID:24065893

  16. Potential long-term benefits of acute hypothermia after spinal cord injury: assessments with somatosensory-evoked potentials.

    PubMed

    Maybhate, Anil; Hu, Charles; Bazley, Faith A; Yu, Qilu; Thakor, Nitish V; Kerr, Candace L; All, Angelo H

    2012-02-01

    Neuroprotection by hypothermia has been an important research topic over last two decades. In animal models of spinal cord injury, the primary focus has been assessing the effects of hypothermia on behavioral and histologic outcomes. Although a few studies have investigated electrophysiological changes in descending motor pathways with motor-evoked potentials recorded during cooling, we report here hypothermia induced increased electrical conduction in the ascending spinal cord pathways with somatosensory-evoked potentials in injured rats. In our experiments, these effects lasted long after the acute hypothermia and were accompanied by potential long-term improvements in motor movement. Laboratory investigation. University medical school. Twenty-one female Lewis rats. Hypothermia. All animals underwent spinal cord contusion with the NYU-Impactor by a 12.5-mm weight drop at thoracic vertebra T8. A group (n = 10) was randomly assigned for a systemic 2-hr hypothermia episode (32 ± 0.5°C) initiated approximately 2.0 hrs postinjury. Eleven rats were controls with postinjury temperature maintained at 37 ± 0.5°C for 2 hrs. The two groups underwent preinjury, weekly postinjury (up to 4 wks) somatosensory-evoked potential recordings and standard motor behavioral tests (BBB). Three randomly selected rats from each group were euthanized for histologic analysis at postinjury day 3 and day 28. Compared with controls, the hypothermia group showed significantly higher postinjury somatosensory-evoked potential amplitudes with longer latencies. The BBB scores were also higher immediately after injury and 4 wks later in the hypothermia group. Importantly, specific changes in the Basso, Beattie, Bresnahan scores in the hypothermia group (not seen in controls) indicated regained functions critical for motor control. Histologic evaluations showed more tissue preservation in the hypothermia group. After spinal cord injury, early systemic hypothermia provided significant

  17. Auditory evoked potentials from the cortex: audiology applications.

    PubMed

    Cone-Wesson, Barbara; Wunderlich, Julia

    2003-10-01

    The audiological applications of cortical auditory evoked potentials are reviewed. Cortical auditory evoked potentials have some advantages compared with more commonly used techniques such as the auditory brainstem response, because they are more closely tied to perception and can be evoked by complex sounds such as speech. These response characteristics suggest that these potentials could be used clinically in the estimation of threshold and also to assess speech discrimination and perception. Clinical uses of auditory evoked potentials include threshold estimation and their use as an electrophysiological index of auditory system development, auditory discrimination and speech perception, and the benefits from cochlear implantation, auditory training, or amplification. Cortical auditory evoked potentials obtained in passively alert adults have a remarkably high correspondence with perceptual threshold. Acoustic features of complex sounds may be reflected in the waveform and latency of these potentials and so might be used to determine the integrity of neural encoding for such features and thus contribute to speech perception assessment. MMN and P3 have been used to discern discrimination abilities among groups of normal-hearing and hearing-impaired individuals; however, their sensitivity and specificity for testing an individual's abilities has not yet been established. Cortical auditory potentials are affected by listening experience and attention and so could be used to gauge the effects of aural habilitation. The presence of cortical potentials in children with auditory neuropathy appears to indicate residual hearing abilities. Parametric and developmental research is needed to further establish these applications in audiology.

  18. Multiple Color Stimulus Induced Steady State Visual Evoked Potentials

    DTIC Science & Technology

    2007-11-02

    MULTIPLE COLOR STIMULUS INDUCED STEADY STATE VISUAL EVOKED POTENTIALS M. Cheng, X. Gao, S. Gao, D. Xu Institute of Biomedical Engineering...characteristics of high SNR and effectiveness in short-term identification of evoked responses. In most of the SSVEP experiments, single high...frequency stimuli are used. To characterize the complex rhythms in SSVEP, a new multiple color stimulus pattern is proposed in this paper. FFT and

  19. Diagnostic accuracy of evoked potentials for functional impairment after contusive spinal cord injury in adult rats.

    PubMed

    Thirumala, Parthasarathy; Zhou, James; Krishnan, Rohan; Manem, Nihita; Umredkar, Shreya; Hamilton, D K; Balzer, Jeffrey R; Oudega, Martin

    2016-03-01

    Iatrogenic spinal cord injury (SCI) is a cause of potentially debilitating post-operative neurologic complications. Currently, intra-operative neurophysiological monitoring (IONM) via somatosensory evoked potentials and motor-evoked potentials is used to detect and prevent impending SCI. However, no empirically validated interventions exist to halt the progression of iatrogenic SCI once it is detected. This is in part due to the lack of a suitable translational model that mimics the circumstances surrounding iatrogenic SCI detected via IONM. Here, we evaluate a model of simulated contusive iatrogenic SCI detected via IONM in adult female Sprague-Dawley rats. We show that transient losses of somatosensory evoked potentials responses are 88.24% sensitive (95% confidence interval [CI] 63.53-98.20) and 80% specific (95% CI 51.91-95.43) for significant functional impairment following simulated iatrogenic SCI. Similarly, we show that transient losses in motor-evoked potentials responses are 70.83% sensitive (95% CI 48.91-87.33) and 100% specific (95% CI 62.91-100.00) for significant functional impairment following simulated iatrogenic SCI. These results indicate that our model is a suitable replica of the circumstances surrounding clinical iatrogenic SCI.

  20. Efficacy of intraoperative monitoring of transcranial electrical stimulation-induced motor evoked potentials and spontaneous electromyography activity to identify acute-versus delayed-onset C-5 nerve root palsy during cervical spine surgery: clinical article.

    PubMed

    Bhalodia, Vidya M; Schwartz, Daniel M; Sestokas, Anthony K; Bloomgarden, Gary; Arkins, Thomas; Tomak, Patrick; Gorelick, Judith; Wijesekera, Shirvinda; Beiner, John; Goodrich, Isaac

    2013-10-01

    Deltoid muscle weakness due to C-5 nerve root injury following cervical spine surgery is an uncommon but potentially debilitating complication. Symptoms can manifest upon emergence from anesthesia or days to weeks following surgery. There is conflicting evidence regarding the efficacy of spontaneous electromyography (spEMG) monitoring in detecting evolving C-5 nerve root compromise. By contrast, transcranial electrical stimulation-induced motor evoked potential (tceMEP) monitoring has been shown to be highly sensitive and specific in identifying impending C-5 injury. In this study the authors sought to 1) determine the frequency of immediate versus delayed-onset C-5 nerve root injury following cervical spine surgery, 2) identify risk factors associated with the development of C-5 palsies, and 3) determine whether tceMEP and spEMG neuromonitoring can help to identify acutely evolving C-5 injury as well as predict delayed-onset deltoid muscle paresis. The authors retrospectively reviewed the neuromonitoring and surgical records of all patients who had undergone cervical spine surgery involving the C-4 and/or C-5 level in the period from 2006 to 2008. Real-time tceMEP and spEMG monitoring from the deltoid muscle was performed as part of a multimodal neuromonitoring protocol during all surgeries. Charts were reviewed to identify patients who had experienced significant changes in tceMEPs and/or episodes of neurotonic spEMG activity during surgery, as well as those who had shown new-onset deltoid weakness either immediately upon emergence from the anesthesia or in a delayed fashion. Two hundred twenty-nine patients undergoing 235 cervical spine surgeries involving the C4-5 level served as the study cohort. The overall incidence of perioperative C-5 nerve root injury was 5.1%. The incidence was greatest (50%) in cases with dual corpectomies at the C-4 and C-5 spinal levels. All patients who emerged from anesthesia with deltoid weakness had significant and unresolved

  1. Steady-State Somatosensory Evoked Potential for Brain-Computer Interface—Present and Future

    PubMed Central

    Ahn, Sangtae; Kim, Kiwoong; Jun, Sung Chan

    2016-01-01

    Brain-computer interface (BCI) performance has achieved continued improvement over recent decades, and sensorimotor rhythm-based BCIs that use motor function have been popular subjects of investigation. However, it remains problematic to introduce them to the public market because of their low reliability. As an alternative resolution to this issue, visual-based BCIs that use P300 or steady-state visually evoked potentials (SSVEPs) seem promising; however, the inherent visual fatigue that occurs with these BCIs may be unavoidable. For these reasons, steady-state somatosensory evoked potential (SSSEP) BCIs, which are based on tactile selective attention, have gained increasing attention recently. These may reduce the fatigue induced by visual attention and overcome the low reliability of motor activity. In this literature survey, recent findings on SSSEP and its methodological uses in BCI are reviewed. Further, existing limitations of SSSEP BCI and potential future directions for the technique are discussed. PMID:26834611

  2. Steady-State Somatosensory Evoked Potential for Brain-Computer Interface-Present and Future.

    PubMed

    Ahn, Sangtae; Kim, Kiwoong; Jun, Sung Chan

    2015-01-01

    Brain-computer interface (BCI) performance has achieved continued improvement over recent decades, and sensorimotor rhythm-based BCIs that use motor function have been popular subjects of investigation. However, it remains problematic to introduce them to the public market because of their low reliability. As an alternative resolution to this issue, visual-based BCIs that use P300 or steady-state visually evoked potentials (SSVEPs) seem promising; however, the inherent visual fatigue that occurs with these BCIs may be unavoidable. For these reasons, steady-state somatosensory evoked potential (SSSEP) BCIs, which are based on tactile selective attention, have gained increasing attention recently. These may reduce the fatigue induced by visual attention and overcome the low reliability of motor activity. In this literature survey, recent findings on SSSEP and its methodological uses in BCI are reviewed. Further, existing limitations of SSSEP BCI and potential future directions for the technique are discussed.

  3. [Application of evoked potentials monitoring in total thoracoabdominal aorta aneurysm repair].

    PubMed

    Duan, Y Y; Zheng, J; Pan, X D; Zhu, J M; Liu, Y M; Ge, Y P; Cheng, L J; Sun, L Z

    2016-04-05

    To evaluate the application value of evoked potentials (EP) monitoring in patients undergoing aorta-iliac bypass for total thoracoabdominal aorta aneurysm repair (tTAAAR). A prospective study, with a total of 31 patients undergoing tTAAAR and intraoperative EP monitoring from June 2014 to April 2015 was carried out. The results of intraoperative evoked potentials, clinical outcomes and follow-up data of patients were collected for further evaluation. The EP wave disappeared [motor evoked potentials for (55.6±18.1) min, somatosensory evoked potentials for (50.3±18.7) min] after proximal descending aorta being clamped, and gradually recovered after the segment arteries of spine cord were reconstructed. The EP wave was restored to normal level at the end of operation in all the cases. The somatosensory evoked potentials remained unchanged in 2 cases (false negative). One case died after operation. No spinal cord injury occurred. The median follow-up after operation was 10 months (5-14 months). There was no delayed neurological deficit. EP provided an on-line monitoring of the condition of spinal cord function, which become an intraoperative protocol to avoid the irreversible injury of spinal cord.

  4. Visual and brainstem auditory evoked potentials in infants with severe vitamin B12 deficiency.

    PubMed

    Demir, Nihat; Koç, Ahmet; Abuhandan, Mahmut; Calik, Mustafa; Işcan, Akin

    2015-01-01

    Vitamin B12 plays an important role in the development of mental, motor, cognitive, and social functions via its role in DNA synthesis and nerve myelination. Its deficiency in infants might cause neuromotor retardation as well as megaloblastic anemia. The objective of this study was to investigate the effects of infantile vitamin B12 deficiency on evoked brain potentials and determine whether improvement could be obtained with vitamin B12 replacement at appropriate dosages. Thirty patients with vitamin B12 deficiency and 30 age-matched healthy controls were included in the study. Hematological parameters, visual evoked potentials, and brainstem auditory evoked potentials tests were performed prior to treatment, 1 week after treatment, and 3 months after treatment. Visual evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs) were found to be prolonged in 16 (53.3%) and 15 (50%) patients, respectively. Statistically significant improvements in VEP and BAEP examinations were determined 3 months after treatment. Three months after treatment, VEP and BAEP examinations returned to normal in 81.3% and 53.3% of subjects with prolonged VEPs and BAEPs, respectively. These results demonstrate that vitamin B12 deficiency in infants causes significant impairment in the auditory and visual functioning tests of the brain, such as VEP and BAEP.

  5. Vestibular receptors contribute to cortical auditory evoked potentials.

    PubMed

    Todd, Neil P M; Paillard, Aurore C; Kluk, Karolina; Whittle, Elizabeth; Colebatch, James G

    2014-03-01

    Acoustic sensitivity of the vestibular apparatus is well-established, but the contribution of vestibular receptors to the late auditory evoked potentials of cortical origin is unknown. Evoked potentials from 500 Hz tone pips were recorded using 70 channel EEG at several intensities below and above the vestibular acoustic threshold, as determined by vestibular evoked myogenic potentials (VEMPs). In healthy subjects both auditory mid- and long-latency auditory evoked potentials (AEPs), consisting of Na, Pa, N1 and P2 waves, were observed in the sub-threshold conditions. However, in passing through the vestibular threshold, systematic changes were observed in the morphology of the potentials and in the intensity dependence of their amplitude and latency. These changes were absent in a patient without functioning vestibular receptors. In particular, for the healthy subjects there was a fronto-central negativity, which appeared at about 42 ms, referred to as an N42, prior to the AEP N1. Source analysis of both the N42 and N1 indicated involvement of cingulate cortex, as well as bilateral superior temporal cortex. Our findings are best explained by vestibular receptors contributing to what were hitherto considered as purely auditory evoked potentials and in addition tentatively identify a new component that appears to be primarily of vestibular origin.

  6. A Comprehensive Review on Methodologies Employed for Visual Evoked Potentials

    PubMed Central

    Kothari, Ruchi; Bokariya, Pradeep; Singh, Smita; Singh, Ramji

    2016-01-01

    Visual information is fundamental to how we appreciate our environment and interact with others. The visual evoked potential (VEP) is among those evoked potentials that are the bioelectric signals generated in the striate and extrastriate cortex when the retina is stimulated with light which can be recorded from the scalp electrodes. In the current paper, we provide an overview of the various modalities, techniques, and methodologies which have been employed for visual evoked potentials over the years. In the first part of the paper, we cast a cursory glance on the historical aspect of evoked potentials. Then the growing clinical significance and advantages of VEPs in clinical disorders have been briefly described, followed by the discussion on the earlier and currently available methods for VEPs based on the studies in the past and recent times. Next, we mention the standards and protocols laid down by the authorized agencies. We then summarize the recently developed techniques for VEP. In the concluding section, we lay down prospective research directives related to fundamental and applied aspects of VEPs as well as offering perspectives for further research to stimulate inquiry into the role of visual evoked potentials in visual processing impairment related disorders. PMID:27034907

  7. Noninvasive recordings of cochlear evoked potentials in Meniere's disease.

    PubMed

    Podoshin, L; Ben-David, Y; Pratt, H; Fradis, M; Feiglin, H

    1986-08-01

    Noninvasive meatal electrocochleography simultaneously recorded with brain stem auditory evoked potentials were performed on 24 adult patients with unilateral Meniere's disease. Data from the affected ear were compared with those of the nonaffected ear and with those of ten healthy normally hearing adults. The most striking finding was the significant deviation from the norm of the nonaffected ears' action potential duration. The combination of simultaneously recorded surface meatal electrocochleography and brain stem auditory evoked potentials complement the diagnostic battery of Meniere's disease in ruling out retrocochlear involvement, indicating cochlear involvement of the affected ear, and revealing subclinical changes in the contralateral ears.

  8. Some effects of room acoustics on evoked auditory potentials.

    PubMed

    MARSH, J T; WORDEN, F G; HICKS, L

    1962-07-27

    Auditory potentials were recorded from bipolar electrodes chronically implanted in the cochlear nuclei of four cats. In a training box modified to reduce echoes these animals were exposed to clicks and tone pulses presented from an overhead speaker. Slight changes in the position of the animal in the resulting sound field produced marked changes in the potentials evoked from the cochlear nucleus. These phenomena were observed in the unanesthetized, unrestrained subjects as well as in those under Nembutal anesthesia. It is suggested that these acoustic effects complicate the analysis and interpretation of potentials evoked from the cochlear nucleus under conditions of habituation, shifts in attention, and learning.

  9. [Exogenous evoked potentials in adolesccents with muftiple sclerosis].

    PubMed

    Kroczka, Sławomir; Steczkowska, Małgorzata; Kaciński, Marek

    2016-01-01

    Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system. The disease usually affects young people, with a peak onset between the ages of 20 and 40, although it may also occur in early childhood. MS is one of the most common reasons of disability in young people. Aim of the study. The aim of the study was a neurophysiological characterisation of patients with relapsing-remitting MS (RRMS) eligible to receive an. In this study 23 patients have been included. According to initial symptoms two categories of patients were identified: in one group [group 1] (12123) there were patients with focal signs such as motor andlor sensory abnormalities while the second one [group 2] (11123) consisted of patients with retrobulbar optic neuritis. There were no significant differences in VEP latencies and amplitudes in both I and 2 group. In both groups a significant latency prolongation as well as P100 amplitude decrease has been observed in comparison to the control group. Furthermore, the study has shown that the average latencies of N75 and N135 in group 2 were prolongated when compared to the control group. In BAEP examination no statistically relevant differences have been observed between average latencies and interlatencies in group I and group 2 as well as between the two test groups and control group. In SSEP examination group I has demonstrated a substantial latency prolongation of P14, NIB and N20 when compared to the control group, and the same result for P14, N20, P25 and CCT has been detected in group 2. The average amplitudes of all waves in group I were insignificantly lower than in the control group. In group 2 an insignificant decrease of amplitudes P9 and P18 from the control group has been noticed. In contrast, P25 amplitude was significantly lower. I. Visual evoked potentials test is an effective neurophysiological method in a diagnosis of subclinical focal demyelination in CNS. 2. Auditory pathway is highly

  10. Potential Long Term Benefits of Acute Hypothermia after Spinal Cord Injury: Assessments with Somatosensory Evoked Potentials

    PubMed Central

    Maybhate, Anil; Hu, Charles; Bazley, Faith A.; Yu, Qilu; Thakor, Nitish V.; Kerr, Candace L.; All, Angelo H.

    2011-01-01

    Objective Neuroprotection by hypothermia has been an important research topic over last two decades. In animal models of spinal cord injury (SCI), the primary focus has been assessing effects of hypothermia on behavioral and histological outcomes. While a few studies have investigated electrophysiological changes in descending motor pathways with motor evoked potentials recorded during cooling, we report here, hypothermia induced increased electrical conduction in the ascending spinal cord pathways with somatosensory evoked potentials (SSEPs) in injured rats. In our experiments these effects lasted long after the acute hypothermia and were accompanied with potential long term improvements in motor movement. Design Laboratory Investigation. Setting University Medical School. Subjects 21 Female Lewis Rats. Interventions Hypothermia. Measurements and Main Results All animals underwent spinal cord contusion, with the NYU-Impactor, by a 12.5mm weight drop at thoracic vertebra T8. A group (n=10) was randomly assigned for a systemic 2hr. hypothermia episode (32±0.5°C) initiated ~2.0hrs post-injury. 11 rats were controls with post-injury temperature maintained at 37±0.5°C for 2hrs. The two groups underwent pre-injury, weekly post-injury (up to 4wks) SSEP recordings and standard motor behavioral tests (BBB). Three randomly selected rats from each group were euthanized for histological analysis at post-injury Day 3 and Day 28. Compared to controls, the hypothermia group showed significantly higher SSEP amplitudes post-injury; with longer latencies. The BBB scores were also higher immediately after injury and 4 weeks later in the hypothermia group. Importantly, specific changes in the BBB scores in hypothermia group (not seen in controls) indicated regained functions critical for motor control. Histological evaluations showed more tissue preservation in hypothermia group. Conclusions Post-SCI, early systemic hypothermia provided significant neuroprotection weeks after

  11. The Duration of Motor Responses Evoked with Intracortical Microstimulation in Rats Is Primarily Modulated by Stimulus Amplitude and Train Duration

    PubMed Central

    Watson, Meghan; Sawan, Mohamad

    2016-01-01

    Microstimulation of brain tissue plays a key role in a variety of sensory prosthetics, clinical therapies and research applications, however the effects of stimulation parameters on the responses they evoke remain widely unknown. In particular, the effects of parameters when delivered in the form of a stimulus train as opposed to a single pulse are not well understood despite the prevalence of stimulus train use. We aimed to investigate the contribution of each parameter of a stimulus train to the duration of the motor responses they evoke in forelimb muscles. We used constant-current, biphasic, square wave pulse trains in acute terminal experiments under ketamine anaesthesia. Stimulation parameters were systematically tested in a pair-wise fashion in the caudal forelimb region of the motor cortex in 7 Sprague-Dawley rats while motor evoked potential (MEP) recordings from the forelimb were used to quantify the influence of each parameter in the train. Stimulus amplitude and train duration were shown to be the dominant parameters responsible for increasing the total duration of the MEP, while interphase interval had no effect. Increasing stimulus frequency from 100–200 Hz or pulse duration from 0.18–0.34 ms were also effective methods of extending response durations. Response duration was strongly correlated with peak time and amplitude. Our findings suggest that motor cortex intracortical microstimulations are often conducted at a higher frequency rate and longer train duration than necessary to evoke maximal response duration. We demonstrated that the temporal properties of the evoked response can be both predicted by certain response metrics and modulated via alterations to the stimulation signal parameters. PMID:27442588

  12. The Duration of Motor Responses Evoked with Intracortical Microstimulation in Rats Is Primarily Modulated by Stimulus Amplitude and Train Duration.

    PubMed

    Watson, Meghan; Sawan, Mohamad; Dancause, Numa

    2016-01-01

    Microstimulation of brain tissue plays a key role in a variety of sensory prosthetics, clinical therapies and research applications, however the effects of stimulation parameters on the responses they evoke remain widely unknown. In particular, the effects of parameters when delivered in the form of a stimulus train as opposed to a single pulse are not well understood despite the prevalence of stimulus train use. We aimed to investigate the contribution of each parameter of a stimulus train to the duration of the motor responses they evoke in forelimb muscles. We used constant-current, biphasic, square wave pulse trains in acute terminal experiments under ketamine anaesthesia. Stimulation parameters were systematically tested in a pair-wise fashion in the caudal forelimb region of the motor cortex in 7 Sprague-Dawley rats while motor evoked potential (MEP) recordings from the forelimb were used to quantify the influence of each parameter in the train. Stimulus amplitude and train duration were shown to be the dominant parameters responsible for increasing the total duration of the MEP, while interphase interval had no effect. Increasing stimulus frequency from 100-200 Hz or pulse duration from 0.18-0.34 ms were also effective methods of extending response durations. Response duration was strongly correlated with peak time and amplitude. Our findings suggest that motor cortex intracortical microstimulations are often conducted at a higher frequency rate and longer train duration than necessary to evoke maximal response duration. We demonstrated that the temporal properties of the evoked response can be both predicted by certain response metrics and modulated via alterations to the stimulation signal parameters.

  13. Familial influences on cortical evoked potentials in migraine.

    PubMed

    Sándor, P S; Afra, J; Proietti-Cecchini, A; Albert, A; Schoenen, J

    1999-04-26

    Cortical information processing in migraine patients is impaired between attacks, showing deficient habituation of pattern-reversal visual evoked potentials (VEP), and strong intensity dependence of auditory cortical evoked potentials (IDAP). This could be a genetic trait as certain genetic patterns are known for evoked potentials in healthy subjects. We investigated VEP habituation and IDAP in 20 pairs of migraineurs made up of parents and their children. Using a Monte-Carlo statistical method, we selectively assessed vertical familial influences. VEP habituation and IDAP were abnormal in both parents and children. However, similarity was far more pronounced between related pairs than between unrelated pairs. Familial influences are highly significant in determinants of cortical information processing in migraineurs, hence supporting the important role of genetic factors.

  14. Obtaining single stimulus evoked potentials with wavelet denoising

    NASA Astrophysics Data System (ADS)

    Quian Quiroga, R.

    2000-11-01

    We present a method for the analysis of electroencephalograms (EEG). In particular, small signals due to stimulation, so-called evoked potentials (EPs), have to be detected in the background EEG. This is achieved by using a denoising implementation based on the wavelet decomposition. One recording of visual evoked potentials, and recordings of auditory evoked potentials from four subjects corresponding to different age groups are analyzed. We find higher variability in older individuals. Moreover, since the EPs are identified at the single stimulus level (without need of ensemble averaging), this will allow the calculation of better resolved averages. Since the method is parameter free (i.e. it does not need to be adapted to the particular characteristics of each recording), implementations in clinical settings are imaginable.

  15. Effect of ischaemia on somatosensory evoked potentials in diabetic patients.

    PubMed Central

    López-Alburquerque, T; García Miguel, A; Ruiz Ezquerro, J J; de Portugal Alvarez, J

    1987-01-01

    The nerve action potential at the elbow and somatosensory evoked potentials (SEPs) at the scalp were recorded over 30 minutes of tourniquet-induced limb ischaemia in 10 diabetic patients and 10 controls. According to the SEP changes, an increased resistance to nerve ischaemia in diabetic patients was observed. The pathways involved in SEP conduction are discussed. PMID:3585354

  16. Attenuation of auditory evoked potentials for hand and eye-initiated sounds.

    PubMed

    Mifsud, Nathan G; Beesley, Tom; Watson, Tamara L; Whitford, Thomas J

    2016-10-01

    Reduction of auditory event-related potentials (ERPs) to self-initiated sounds has been considered evidence for a predictive model in which copies of motor commands suppress sensory representations of incoming stimuli. However, in studies which involve arbitrary auditory stimuli evoked by sensory-unspecific motor actions, learned associations may underlie ERP differences. Here, in a new paradigm, eye motor output generated auditory sensory input, a naïve action-sensation contingency. We measured the electroencephalogram (EEG) of 40 participants exposed to pure tones, which they produced with either a button-press or volitional saccade. We found that button-press-initiated stimuli evoked reduced amplitude compared to externally initiated stimuli for both the N1 and P2 ERP components, whereas saccade-initiated stimuli evoked intermediate attenuation at N1 and no reduction at P2. These results indicate that the motor-to-sensory mapping involved in speech production may be partly generalized to other contingencies, and that learned associations also contribute to the N1 attenuation effect.

  17. [Brain stem auditory evoked potentials in brain death state].

    PubMed

    Kojder, I; Garell, S; Włodarczyk, E; Sagan, L; Jezewski, D; Slósarek, J

    1998-01-01

    The authors studied auditory brainstem evoked potentials (BAEP) in 27 organ donors aged 40 to 68 years treated in neurosurgery units in Szczecin and Grenoble. Abnormal results were found in all cases. In 63% of cases no evoked action potentials were obtained, in 34% only the 1st wave was obtained, and in two cases evolution was observed with activity extinction. The authors believe that in the process of shaping of BAEP morphotic extinction begins from the later waves to earlier ones in agreement with the rostrocaudal direction of extinction of the functions or brain midline structures, and in a single study various findings may be obtained.

  18. Cortical evoked potentials to an auditory illusion: binaural beats.

    PubMed

    Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

    2009-08-01

    To define brain activity corresponding to an auditory illusion of 3 and 6Hz binaural beats in 250Hz or 1000Hz base frequencies, and compare it to the sound onset response. Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000Hz to one ear and 3 or 6Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3Hz and 6Hz, in base frequencies of 250Hz and 1000Hz. Tones were 2000ms in duration and presented with approximately 1s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. All stimuli evoked tone-onset P(50), N(100) and P(200) components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P(50) had significantly different sources than the beats-evoked oscillations; and N(100) and P(200) sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp.

  19. Cortical Evoked Potentials to an Auditory Illusion: Binaural Beats

    PubMed Central

    Pratt, Hillel; Starr, Arnold; Michalewski, Henry J.; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

    2009-01-01

    Objective: To define brain activity corresponding to an auditory illusion of 3 and 6 Hz binaural beats in 250 Hz or 1,000 Hz base frequencies, and compare it to the sound onset response. Methods: Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000 Hz to one ear and 3 or 6 Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3 Hz and 6 Hz, in base frequencies of 250 Hz and 1000 Hz. Tones were 2,000 ms in duration and presented with approximately 1 s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. Results: All stimuli evoked tone-onset P50, N100 and P200 components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P50 had significantly different sources than the beats-evoked oscillations; and N100 and P200 sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Conclusions: Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Significance: Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the

  20. Motor behaviors in the sheep evoked by electrical stimulation of the subthalamic nucleus.

    PubMed

    Lentz, Linnea; Zhao, Yan; Kelly, Matthew T; Schindeldecker, William; Goetz, Steven; Nelson, Dwight E; Raike, Robert S

    2015-11-01

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is used to treat movement disorders, including advanced Parkinson's disease (PD). The pathogenesis of PD and the therapeutic mechanisms of DBS are not well understood. Large animal models are essential for investigating the mechanisms of PD and DBS. The purpose of this study was to develop a novel sheep model of STN DBS and quantify the stimulation-evoked motor behaviors. To do so, a large sample of animals was chronically-implanted with commercial DBS systems. Neuroimaging and histology revealed that the DBS leads were implanted accurately relative to the neurosurgical plan and also precisely relative to the STN. It was also possible to repeatedly conduct controlled evaluations of stimulation-evoked motor behavior in the awake-state. The evoked motor responses depended on the neuroanatomical location of the electrode contact selected for stimulation, as contacts proximal to the STN evoked movements at significantly lower voltages. Tissue stimulation modeling demonstrated that selecting any of the contacts stimulated the STN, whereas selecting the relatively distal contacts often also stimulated thalamus but only the distal-most contact stimulated internal capsule. The types of evoked motor behaviors were specific to the stimulation frequency, as low but not high frequencies consistently evoked movements resembling human tremor or dyskinesia. Electromyography confirmed that the muscle activity underlying the tremor-like movements in the sheep was consistent with human tremor. Overall, this work establishes that the sheep is a viable a large-animal platform for controlled testing of STN DBS with objective motor outcomes. Moreover, the results support the hypothesis that exaggerated low-frequency activity within individual nodes of the motor network can drive symptoms of human movement disorders, including tremor and dyskinesia. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. [Anesthetic and physiologic implications of neurophysiologic monitoring with evoked potentials during spinal surgery].

    PubMed

    Valverde Junguito, J L; Aldana Díaz, E M; Pérez Lorensu, P J; González Miranda, F

    2007-04-01

    Neurophysiologic monitoring with somatosensory and motor evoked potentials in spinal surgery is now widely applied in order to reduce the risk of neural injury and facilitate intraoperative decision making. Most anesthetics affect such monitoring by altering both somatosensory and motor evoked responses and these effects may place constraints on the choice of anesthetic. Intraoperative management includes maintaining stable physiologic conditions, which involves adjusting hemodynamic parameters, maintaining normal blood flow to promote proper oxygen exchange, ensuring proper ventilation, and avoiding variations in temperature. Close collaboration between the anesthetist, the surgeon, and the neurophysiologist will ensure the success of intraoperative monitoring and make it possible to avoid neural injury by making timely changes in the surgical approach.

  2. Motor Neuron-Specific Overexpression of the Presynaptic Choline Transporter: Impact on Motor Endurance and Evoked Muscle Activity

    PubMed Central

    Lund, David; Ruggiero, Alicia M.; Ferguson, Shawn M.; Wright, Jane; English, Brett A.; Reisz, Peter A.; Whitaker, Sarah M.; Peltier, Amanda C.; Blakely, Randy D.

    2010-01-01

    The presynaptic, hemicholinium-3 sensitive, high-affinity choline transporter (CHT) supplies choline for acetylcholine (ACh) synthesis. In mice, a homozygous deletion of CHT (CHT−/−) leads to premature cessation of spontaneous or evoked neuromuscular signaling and is associated with perinatal cyanosis and lethality within 1 hr. Heterozygous (CHT+/−) mice exhibit diminished brain ACh levels and demonstrate an inability to sustain vigorous motor activity. We sought to explore the contribution of CHT gene dosage to motor function in greater detail using transgenic mice where CHT is expressed under control of the motor neuron promoter Hb9 (Hb9:CHT). On a CHT−/− background, the Hb9:CHT transgene conferred mice with the ability to move and breath for a postnatal period of ~24 hrs, thus increasing survival. Conversely, Hb9:CHT expression on a wild-type background (CHT+/+;Hb9:CHT) leads to an increased capacity for treadmill running compared to wild-type littermates. Analysis of the stimulated compound muscle action potential (CMAP) in these animals under basal conditions established that CHT+/+;Hb9:CHT mice display an unexpected, bidirectional change, producing either elevated or reduced CMAP amplitude, relative to CHT+/+ animals. To examine whether these two groups arise from underlying changes in synaptic properties, we used high-frequency stimulation of motor axons to assess CMAP recovery kinetics. Although CHT+/+;Hb9:CHT mice in the two groups display an equivalent, time-dependent reduction in CMAP amplitude, animals with a higher basal CMAP amplitude demonstrate a significantly enhanced rate of recovery. To explain our findings, we propose a model whereby CHT support for neuromuscular signaling involves contributions to ACh synthesis as well as cholinergic synaptic vesicle availability. PMID:20888396

  3. Motor neuron-specific overexpression of the presynaptic choline transporter: impact on motor endurance and evoked muscle activity.

    PubMed

    Lund, D; Ruggiero, A M; Ferguson, S M; Wright, J; English, B A; Reisz, P A; Whitaker, S M; Peltier, A C; Blakely, R D

    2010-12-29

    The presynaptic, hemicholinium-3 sensitive, high-affinity choline transporter (CHT) supplies choline for acetylcholine (ACh) synthesis. In mice, a homozygous deletion of CHT (CHT-/-) leads to premature cessation of spontaneous or evoked neuromuscular signaling and is associated with perinatal cyanosis and lethality within 1 h. Heterozygous (CHT+/-) mice exhibit diminished brain ACh levels and demonstrate an inability to sustain vigorous motor activity. We sought to explore the contribution of CHT gene dosage to motor function in greater detail using transgenic mice where CHT is expressed under control of the motor neuron promoter Hb9 (Hb9:CHT). On a CHT-/- background, the Hb9:CHT transgene conferred mice with the ability to move and breath for a postnatal period of ∼24 h, thus increasing survival. Conversely, Hb9:CHT expression on a wild-type background (CHT+/+;Hb9:CHT) leads to an increased capacity for treadmill running compared to wild-type littermates. Analysis of the stimulated compound muscle action potential (CMAP) in these animals under basal conditions established that CHT+/+;Hb9:CHT mice display an unexpected, bidirectional change, producing either elevated or reduced CMAP amplitude, relative to CHT+/+ animals. To examine whether these two groups arise from underlying changes in synaptic properties, we used high-frequency stimulation of motor axons to assess CMAP recovery kinetics. Although CHT+/+; Hb9:CHT mice in the two groups display an equivalent, time-dependent reduction in CMAP amplitude, animals with a higher basal CMAP amplitude demonstrate a significantly enhanced rate of recovery. To explain our findings, we propose a model whereby CHT support for neuromuscular signaling involves contributions to ACh synthesis as well as cholinergic synaptic vesicle availability.

  4. Are somatosensory evoked potentials of the tibial nerve the most sensitive test in diagnosing multiple sclerosis?

    PubMed

    Djuric, S; Djuric, V; Zivkovic, M; Milosevic, V; Jolic, M; Stamenovic, J; Djordjevic, G; Calixto, M

    2010-01-01

    Multiple sclerosis (MS) is mostly diagnosed clinically, but the diagnosis has significantly improved through the use of brain magnetic resonance imaging (MRI), testing of cerebrospinal fluid, and multimodal evoked potentials (MEPs). Even though MRI is the superior method in diagnosing this illness, MEPs remain important because they can detect clinically silent lesions in the sensory and motor pathways of the central nervous system (CNS). The aim of the study is to test the diagnostic sensitivity of MEPs and MRI and the ratio of their sensitivity in patients with MS. The study subjects included 293 patients with MS with disease duration of two to six years: 249 patients with relapsing-remitting (RR) MS and 44 with primary-progressive (PP) MS. All patients were subjected to an MRI brain scan, visual evoked potentials (VEPs), median somatosensory evoked potentials (SEPs), tibial somatosensory evoked potentials (SEPs), and auditory evoked potentials (AEPs). Abnormal Findings Included : changed wave morphology, interside difference in wave amplitude, absolute and interwave latency increased by 2.5 SD as compared with the control group. The control group comprised of 35 healthy subjects. Results : In this study the most abnormal findings were tibial SEPs, median SEPs, and VEPs. Our results suggest different sensitivity of MEPs in patients suffering from different forms of MS. In RR-MS the sensitivity of tibial SEPs was statically significant (Fischer's exact probability test) as compared to other evoked potential modalities. Similarly VEPs were more sensitive as compared to AEPs. In the PP-MS, median SEPs have been found to be more sensitive than VEPs, while tibial SEPs have been found to be more sensitive than AEPs. There was no significant difference in the sensitivity of MRI and MEPs both the forms of MS. Tibial SEPs produce the most abnormal results and the highest sensitivity in the RR-MS. We propose that this test as useful criterion for the diagnosis of MS.

  5. Evoked cochlear potentials in the barn owl.

    PubMed

    Köppl, Christine; Gleich, Otto

    2007-06-01

    Gross electrical responses to tone bursts were measured in adult barn owls, using a single-ended wire electrode placed onto the round window. Cochlear microphonic (CM) and compound action potential (CAP) responses were evaluated separately. Both potentials were physiologically vulnerable. Selective abolishment of neural responses at high frequencies confirmed that the CAP was of neural origin, while the CM remained unaffected. CAP latencies decreased with increasing stimulus frequency and CAP amplitudes were correlated with known variations in afferent fibre numbers from the different papillar regions. This suggests a local origin of the CAP along the tonotopic gradient within the basilar papilla. The audiograms derived from CAP and CM threshold responses both showed a broad frequency region of optimal sensitivity, very similar to behavioural and single-unit data, but shifted upward in absolute sensitivity. CAP thresholds rose above 8 kHz, while CM responses showed unchanged sensitivity up to 10 kHz.

  6. On hemispheric differences in evoked potentials to speech stimuli

    NASA Technical Reports Server (NTRS)

    Galambos, R.; Benson, P.; Smith, T. S.; Schulman-Galambos, C.; Osier, H.

    1975-01-01

    Confirmation is provided for the belief that evoked potentials may reflect differences in hemispheric functioning that are marginal at best. Subjects were right-handed and audiologically normal men and women, and responses were recorded using standard EEG techniques. Subjects were instructed to listen for the targets while laying in a darkened sound booth. Different stimuli, speech and tone signals, were used. Speech sounds were shown to evoke a response pattern that resembles that to tone or clicks. Analysis of variances on peak amplitude and latency measures showed no significant differences between hemispheres, however, a Wilcoxon test showed significant differences in hemispheres for certain target tasks.

  7. Spinal evoked potentials in the primate: neural substrate.

    PubMed

    Cusick, J F; Myklebust, J; Larson, S J; Sances, A

    1978-10-01

    Summated responses evoked by peripheral nerve stimulation were recorded from electrodes located in the epidural and subdural spaces anterior and posterior to the monkey spinal cord. Segmental microsurgical resection of the dorsal columns both at the thoracic and cervical levels resulted in total obliteration of the response recorded rostral to these lesions. Isolated segmental dorsal column preservation did not significantly alter response latency or wave form recorded at the rostral electrodes. Bilateral cervical dorsolateral column resection also resulted in no discernible alterations of these responses. These data indicate that spinal evoked potentials recorded from levels rostral to their root entry zones arise almost exclusively from the dorsal columns.

  8. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    ERIC Educational Resources Information Center

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

    In some cochlear implant users, success is not achieved in spite of optimal clinical factors (including age at implantation, duration of rehabilitation and post-implant hearing level), which may be attributed to disorders at higher levels of the auditory pathway. We used cortical auditory evoked potentials to investigate the ability to perceive…

  9. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    ERIC Educational Resources Information Center

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

    In some cochlear implant users, success is not achieved in spite of optimal clinical factors (including age at implantation, duration of rehabilitation and post-implant hearing level), which may be attributed to disorders at higher levels of the auditory pathway. We used cortical auditory evoked potentials to investigate the ability to perceive…

  10. Evaluation of Evoked Potentials to Dyadic Tones after Cochlear Implantation

    ERIC Educational Resources Information Center

    Sandmann, Pascale; Eichele, Tom; Buechler, Michael; Debener, Stefan; Jancke, Lutz; Dillier, Norbert; Hugdahl, Kenneth; Meyer, Martin

    2009-01-01

    Auditory evoked potentials are tools widely used to assess auditory cortex functions in clinical context. However, in cochlear implant users, electrophysiological measures are challenging due to implant-created artefacts in the EEG. Here, we used independent component analysis to reduce cochlear implant-related artefacts in event-related EEGs of…

  11. Evaluation of Evoked Potentials to Dyadic Tones after Cochlear Implantation

    ERIC Educational Resources Information Center

    Sandmann, Pascale; Eichele, Tom; Buechler, Michael; Debener, Stefan; Jancke, Lutz; Dillier, Norbert; Hugdahl, Kenneth; Meyer, Martin

    2009-01-01

    Auditory evoked potentials are tools widely used to assess auditory cortex functions in clinical context. However, in cochlear implant users, electrophysiological measures are challenging due to implant-created artefacts in the EEG. Here, we used independent component analysis to reduce cochlear implant-related artefacts in event-related EEGs of…

  12. Ocular vestibular evoked myogenic potentials in patients with acoustic neuroma.

    PubMed

    Piras, Gianluca; Brandolini, Cristina; Castellucci, Andrea; Modugno, Giovanni Carlo

    2013-02-01

    To assess the usefulness of vestibular testing in patients with acoustic neuroma, considering two main aspects: to compare diagnostic sensitivity of the current vestibular tests, especially considering ocular vestibular evoked myogenic potentials (OVEMPs) and to identify pre-operative localization of the tumor (inferior vestibular nerve vs. superior vestibular nerve) only with the help of vestibular electrophysiological data. Twenty-six patients with unilateral acoustic neuroma (mainly intracanalicular type) were studied with a full audio-vestibular test battery (pure tone and speech audiometry, caloric bithermal test, vibration-induced nystagmus test (VIN), cervical and OVEMPs). 18 patients (69 %) showed abnormal caloric responses. 12 patients (46.2 %) showed a pattern of VIN test suggestive of vestibular asymmetry. 16 patients (61.5 %) showed abnormal OVEMPs (12 only to AC, 4 both to AC and BC). 10 patients (38.5 %) showed abnormal cervical vestibular evoked myogenic potentials (5 both to AC and BC, 5 only to AC). In one case, results of vestibular evoked potentials and caloric test were confirmed by intra-operative and post-operative findings. Results of electrophysiological tests in AN patients could be helpful for planning the proper surgical approach, considering that sensitivity of every exam is quite low in intracanalicular lesion; clinical data allow a better interpretation of vestibular evoked myogenic potentials.

  13. Brainstem Auditory Evoked Potential Study in Children with Autistic Disorder.

    ERIC Educational Resources Information Center

    Wong, Virginia; Wong, Sik Nin

    1991-01-01

    Brainstem auditory evoked potentials were compared in 109 children with infantile autism, 38 with autistic condition, 19 with mental retardation, and 20 normal children. Children with infantile autism or autistic condition had significantly longer brainstem transmission time than normal children suggesting neurological damage as the basis of…

  14. Initial and serial evoked potentials in cerebrovascular critical care patients.

    PubMed

    Haupt, Walter F; Pawlik, Gunter; Thiel, Alexander

    2006-10-01

    Results of somatosensory evoked potential (SEP) and brainstem auditory evoked potential (BAEP) examinations performed early in the clinical course of patients with acute cerebrovascular disease correlate statistically significantly with outcome regardless of type and localization of the primary lesion. The prognostic value of serial examinations of SEP and BAEP has not been studied yet. The authors examined a group of 215 patients suffering from acute stroke requiring neurocritical care composed of 75 supratentorial and 36 infratentorial ischemic strokes, 58 supratentorial and 18 infratentorial hemorrhages, and 28 aneurysmatic subarachnoid hemorrhages prospectively using spinal and cortical SEP and BAEP according to routine procedures on admission as well as after 1 and 2 weeks. The findings were correlated to outcome at 4 weeks. Statistical assessment was performed using standard methods of contingency analysis. In all groups, SEP findings were significantly correlated with outcome at initial and all subsequent examinations, similar correlations were also found for BAEP. However, after partialling out the prognostic information gained from the initial examination of SEP and BAEP, the follow-up examinations rendered only a marginal increase in prognostic information. Therefore, the initial examination of evoked potentials supplies valuable prognostic information, however, serial examinations of evoked potentials during the first weeks of disease improve the prognostic information only marginally.

  15. Somatosensory-evoked potentials and MRI in tuberculous spondylodiscitis.

    PubMed

    Titlic, M; Isgum, V; Buca, A; Kolic, K; Tonkic, A; Jukic, I; Milas, I

    2007-01-01

    Early diagnosis of spondylodiscitis is a condition of efficient conservative treatment. Somatosensory-evoked potentials with clinical examination results are used in assessing the diagnosis, as well as in monitoring the course of disease and healing. MRI clearly shows the inflammatory process, healing and scars. We report a 46-year-old woman suffering from non-specific interscapular pains. The evoked somatosensory potentials of the tibial nerveshow potential conductivity being slowed down through the thoracic spine, which is clearly evident from the prolonged latency and the decreased amplitude of the evoked response. The performed thoracic spine MRI shows spondylodiscitis at the Thl0-11 level. The subject is a nurse administering BCG therapy at a urology clinic, due to the fact of which this was deemed to have been a case of tuberculous spondylodiscitis. Due to the possibility of scattering the causative agent by needle, the biopsy was given up and antituberculous therapy was administered ex juvantibus. The disease was followed up by clinical examinations, somatosensory-evoked potentials and MRI up to fully successful and final recovery from spondylodiscitis. The above examinations are of great help in diagnosing the tuberculous spondylodiscitis and monitoring the recovery (Fig. 6, Ref. 16).

  16. Thermal grill conditioning: Effect on contact heat evoked potentials

    PubMed Central

    Jutzeler, Catherine R.; Warner, Freda M.; Wanek, Johann; Curt, Armin; Kramer, John L. K.

    2017-01-01

    The ‘thermal grill illusion’ (TGI) is a unique cutaneous sensation of unpleasantness, induced through the application of interlacing warm and cool stimuli. While previous studies have investigated optimal parameters and subject characteristics to evoke the illusion, our aim was to examine the modulating effect as a conditioning stimulus. A total of 28 healthy control individuals underwent three testing sessions on separate days. Briefly, 15 contact heat stimuli were delivered to the right hand dorsum, while the left palmar side of the hand was being conditioned with either neutral (32 °C), cool (20 °C), warm (40 °C), or TGI (20/40 °C). Rating of perception (numeric rating scale: 0–10) and evoked potentials (i.e., N1 and N2P2 potentials) to noxious contact heat stimuli were assessed. While cool and warm conditioning decreased cortical responses to noxious heat, TGI conditioning increased evoked potential amplitude (N1 and N2P2). In line with other modalities of unpleasant conditioning (e.g., sound, visual, and olfactory stimulation), cortical and possibly sub-cortical modulation may underlie the facilitation of contact heat evoked potentials. PMID:28079118

  17. [Auditory evoked potentials in individuals over 50 years].

    PubMed

    Matas, Carla Gentile; Filha, Valdete Alves Valentins dos Santos; Okada, Melissa Mitsue Cunha Pires; Resque, Juliana Reis

    2006-01-01

    auditory evoked potentials. to describe the results of brainstem auditory evoked potentials (PEATE), middle latency auditory evoked potentials (PEAML) and cognitive potential (P300) in individuals over 50 years. this study was developed at the Speech and Hearing Investigation Laboratory in Auditory Evoked Potentials of the Speech-Language and Hearing Course of the Department of Physiotherapy, Speech-language and Hearing Sciences and Occupational Therapy of FMUSP. Twenty four subjects (45 ears) were evaluated through PEATE and P300, and only 18 of these subjects (36 ears) were evaluated through PEAML. All subjects had ages between 51 and 74 years and were divided in three groups: GI (50-59 years), GII (60-69 years) and GIII (70-79 years). All subjects presented either normal hearing or neurossensorial hearing loss of a moderate-severe level in the PEATE, and of a moderate level in the PEAML and in the P300. The frequency range evaluated in the PEATE and in the PEAML varied from 3000 to 6000Hz, while in the P300 it varied from 1000 to 1500Hz. For the statistical analyses of the data, the Kruskal-Wallis test, the Mann-Whitney test and the two proportion equality test were used. significant statistical differences were simultaneously observed between the groups for the interpeak I-V in the PEATE and for the Na wave latency in the PEAML - in the PEATE the difference was caused by GIII and in the PEAML it was caused by GI. A statistically significant difference between the groups was observed for the latency of the P300 component. Considerable alterations were also found regarding the quality of the responses of the auditory evoked potentials, indicating a strong correlation between the deterioration of the responses and the increase in age. the aging process of the auditory system progressively affects the auditory pathways throughout the brainstem and temporal lobe.

  18. Auditory evoked potentials and impairments to psychomotor activity evoked by falling asleep.

    PubMed

    Dorokhov, V B; Verbitskaya, Yu S; Lavrova, T P

    2010-05-01

    Sounds provide the most suitable stimuli for studies of information processes occurring in the brain during falling asleep and at different stages of sleep. The widely used analysis of evoked potentials averaged for groups of subjects has a number of disadvantages associated with their individual variability. Thus, in the present study, measures of the individual components of auditory evoked potentials were determined and selectively summed for individual subjects, with subsequent analysis by group. The aim of the present work was to identify measures of auditory evoked potentials providing quantitative assessment of the dynamics of the brain's functional state during the appearance of errors in activity associated with decreases in the level of waking and falling asleep. A monotonous psychomotor test was performed in the lying position with the eyes closed; this consisted of two alternating parts: the first was counting auditory stimuli from 1 to 10 with simultaneous pressing of a button, and the second was counting stimuli from 1 to 5 silently without pressing the button, and so on. Computer-generated sound stimuli (duration 50 msec, envelope filling frequency 1000 Hz, intensity 60 dB) were presented binaurally with interstimulus intervals of 2.4-2.7 sec. A total of 41 subjects took part (both genders, mean age 25 years), of which only 23 fell asleep; data for 14 subjects with sufficient episodes of falling asleep were analyzed. Comparison of measures of auditory evoked potentials (the latencies and amplitudes of the N1, P2, N2, and P3 components) during correct and erroneous psychomotor test trials showed that decreases in the level of consciousness elicited significant increases in the amplitudes of the components of the vertex N1-P2-N2 complex in series without button pressing. The greatest changes in auditory evoked potentials in both series were seen in the N2 component, with latency 330-360 msec, which has a common origin with the EEG theta rhythm and is

  19. Somatosensory evoked potentials following proprioceptive stimulation of finger in man.

    PubMed

    Mima, T; Terada, K; Maekawa, M; Nagamine, T; Ikeda, A; Shibasaki, H

    1996-09-01

    Brisk passive flexion of the proximal interphalangeal joint of the middle finger, produced by using a newly devised instrument, elicited evoked potentials on the scalp. The present study carefully excluded the possible contribution of sensory modalities other than proprioception. The initial part of cortical response was a positive deflexion at the contralateral central area (P1 at 34.6 ms after the stimulus). This was followed by a midfrontal negative wave (N1 at 44.8 ms) and a clear positivity at the contralateral centroparietal area (P2 at 48.0 ms). The evoked responses persisted in spite of the abolition of cutaneous and joint afferents of the finger caused by ischemic anesthesia, but they were lost by ischemic anesthesia of the forearm. Thus, the cortical evoked responses obtained in this study most probably reflect muscle afferent inputs. The scalp distribution of P1 suggested that its cortical generator source was different from that of the N20-P20 components of evoked potentials to electrical median nerve stimulation. Brodmann areas 2 and 3a of human brain, which are known to receive deep receptor inputs, are the most plausible generator sites for the early components of the proprioception-related evoked responses. The amplitude of P2 was related to the velocity but not to the magnitude of movement. In conclusion, the present study established a method for recording the evoked responses to the brisk passive movement of the finger joint, which mainly reflect the dynamic aspects of proprioception mediated through muscle afferent.

  20. Visual evoked potentials in patients after methanol poisoning.

    PubMed

    Urban, Pavel; Zakharov, Sergey; Diblík, Pavel; Pelclová, Daniela; Ridzoň, Petr

    2016-01-01

    We report the results of the visual evoked potentials (VEP) examination in patients after severe poisoning by methanol. The group of 47 patients (38 males and 9 females) was assembled out of persons who survived an outbreak of poisoning by the methanol adulterated alcohol beverages, which happened in the Czech Republic in 2012-2013. The visual evoked potentials examination was performed using monocular checkerboard pattern-reversal stimulation. Two criteria of abnormality were chosen: missing evoked response, and wave P1 latency > 117 ms. Non-parametric statistical methods (median, range, and the median test) were used to analyze factors influencing the VEP abnormality. The visual evoked potential was abnormal in 20 patients (43%), 5 of them had normal visual acuity on the Snellen chart. The VEP abnormality did not correlate significantly with initial serum concentrations of methanol, formic acid or lactate; however, it showed statistically significant inverse relation to the initial serum pH: the subgroup with the abnormal VEP had significantly lower median pH in comparison with the subgroup with the normal VEP (7.16 vs. 7.34, p = 0.04). The abnormality was not related to chronic alcohol abuse. The visual evoked potentials examination appeared sensitive enough to detected even subclinical impairment of the optic system. Metabolic acidosis is likely to be the key factor related to the development of visual damage induced by methanol. The examination performed with a delay of 1-9 months after the poisoning documented the situation relatively early after the event. It is considered as a baseline for the planned long-term follow-up of the patients, which will make it possible to assess the dynamics of the observed changes, their reversibility, and the occurrence of potential late sequelae. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  1. Automatic classification of visual evoked potentials based on wavelet decomposition

    NASA Astrophysics Data System (ADS)

    Stasiakiewicz, Paweł; Dobrowolski, Andrzej P.; Tomczykiewicz, Kazimierz

    2017-04-01

    Diagnosis of part of the visual system, that is responsible for conducting compound action potential, is generally based on visual evoked potentials generated as a result of stimulation of the eye by external light source. The condition of patient's visual path is assessed by set of parameters that describe the time domain characteristic extremes called waves. The decision process is compound therefore diagnosis significantly depends on experience of a doctor. The authors developed a procedure - based on wavelet decomposition and linear discriminant analysis - that ensures automatic classification of visual evoked potentials. The algorithm enables to assign individual case to normal or pathological class. The proposed classifier has a 96,4% sensitivity at 10,4% probability of false alarm in a group of 220 cases and area under curve ROC equals to 0,96 which, from the medical point of view, is a very good result.

  2. [Evoked motor activity and maturation sequence of striate complex structures during chick embryogenesis].

    PubMed

    Gevorgian, E G; Bogdanov, O V; Medvedeva, M V

    1977-01-01

    Morphological and functional maturation of different structures of the striatal complex takes place heterochronously, as revealed in studies on motor activity of 17--21-day chick embryos evoked by electrical stimulation of these structures. Phylogenetically more ancient structures, i. e. archi- and paleostriatum, are the first to be involved into regulation of the motor activity. These structures together with the structures of the midbrain and cerebellum are considered as "the primary" step of regulatory mechanisms which develop during functional maturation of the motor analyser. Neostriatal mechanisms operate from the 19th day of incubation, whereas hyperstriatal ones--only to the day of hatching.

  3. Visual evoked potentials in a patient with prosopagnosia.

    PubMed

    Small, M

    1988-01-01

    Visual evoked potentials (VEPs) were recorded from a 53-year-old man with prosopagnosia during presentation of slides of known and unknown faces and under two control conditions. ANOVA comparisons with a normal male group showed no differences in P100 amplitude, P300 amplitude or P300 latency. There were no significant evoked potential differences between the patient and controls specifically related to the face conditions. There was, however, a significant delay in the latency of P100 from both hemispheres during all types of stimuli. This prolonged latency was asymmetrical, showing a right sided emphasis with the control conditions: pattern reversal and slides of geometric designs. This finding, of a dissociation in the interhemispheric delay, provides physiological evidence of stimulus-specific organisation at an early, sensory level. The fact that the P100 component showed a marked delay, yet P300 fell within normal limits for amplitude and latency, suggests that this patient's problem lies at a perceptual level.

  4. Skin denervation does not alter cortical potentials to surface concentric electrode stimulation: A comparison with laser evoked potentials and contact heat evoked potentials.

    PubMed

    La Cesa, S; Di Stefano, G; Leone, C; Pepe, A; Galosi, E; Alu, F; Fasolino, A; Cruccu, G; Valeriani, M; Truini, A

    2017-09-12

    In the neurophysiological assessment of patients with neuropathic pain, laser evoked potentials (LEPs), contact heat evoked potentials (CHEPs) and the evoked potentials by the intraepidermal electrical stimulation via concentric needle electrode are widely agreed as nociceptive specific responses; conversely, the nociceptive specificity of evoked potentials by surface concentric electrode (SE-PREPs) is still debated. In this neurophysiological study we aimed at verifying the nociceptive specificity of SE-PREPs. We recorded LEPs, CHEPs and SE-PREPs in eleven healthy participants, before and after epidermal denervation produced by prolonged capsaicin application. We also used skin biopsy to verify the capsaicin-induced nociceptive nerve fibre loss in the epidermis. We found that whereas LEPs and CHEPs were suppressed after capsaicin-induced epidermal denervation, the surface concentric electrode stimulation of the same denervated skin area yielded unchanged SE-PREPs. The suppression of LEPs and CHEPs after nociceptive nerve fibre loss in the epidermis indicates that these techniques are selectively mediated by nociceptive system. Conversely, the lack of SE-PREP changes suggests that SE-PREPs do not provide selective information on nociceptive system function. Capsaicin-induced epidermal denervation abolishes laser evoked potentials (LEPs) and contact heat evoked potentials (CHEPs), but leaves unaffected pain-related evoked potentials by surface concentric electrode (SE-PREPs). These findings suggest that unlike LEPs and CHEPs, SE-PREPs are not selectively mediated by nociceptive system. © 2017 European Pain Federation - EFIC®.

  5. Visual evoked potential (VEP): basic concepts and clinical applications.

    PubMed

    Sherman, J

    1979-01-01

    The Visual Evoked Potential is the objective measurement of visual function monitored at the level of the occipital cortex with scalp electrodes. This article summarizes many of the recent clinical applications of the VEP. Included are basic concepts of the VEP and its clinical utilization for the objective assessment of refractive error, visual acuity, amblyopia, binocularity, demyelinating diseases, psychogenic disorders, pre-surgical prediction of post-surgical visual function, visual fields, color blindness and neurological development.

  6. Human Auditory and Visual Unimodal and Biomodal Continuous Evoked Potentials

    DTIC Science & Technology

    1988-03-01

    to amplitude-modulated light stimuli, have been extensively investigated and applied in various fields: system identification studies ( Tweel and Lund...msec ( Tweel and Lunel, 1965, for MFs > 35 Hz; Regan, 1972; Spekreijse et al., 1977). 4.1.2 Auditory continuous evoked potentials Contrary to the visual...researchers ( Tweel and Lunel, 1965; Regan, 1966, 1972; Spckreijse, 1966; Spekreijse et al., 1977; Diamond, 1977; Junker, 1984; Junker and Peio, 1984

  7. Establishing an evoked-potential vision-tracking system

    NASA Technical Reports Server (NTRS)

    Skidmore, Trent A.

    1991-01-01

    This paper presents experimental evidence to support the feasibility of an evoked-potential vision-tracking system. The topics discussed are stimulator construction, verification of the photic driving response in the electroencephalogram, a method for performing frequency separation, and a transient-analysis example. The final issue considered is that of object multiplicity (concurrent visual stimuli with different flashing rates). The paper concludes by discussing several applications currently under investigation.

  8. Pattern-visual evoked potentials in thinner abusers.

    PubMed

    Poblano, A; Lope Huerta, M; Martínez, J M; Falcón, H D

    1996-01-01

    Organic solvents cause injury to lipids of neuronal and glial membranes. A well known characteristic of workers exposed to thinner is optic neuropathy. We decided to look for neurophysiologic signs of visual damage in patients identified as thinner abusers. Pattern reversal visual evoked potentials was performed on 34 thinner abuser patients and 30 controls. P-100 wave latency was found to be longer on abuser than control subjects. Results show the possibility of central alterations on thinner abusers despite absence of clinical symptoms.

  9. Harmonic coupling of steady-state visual evoked potentials.

    PubMed

    Krusienski, Dean J; Allison, Brendan Z

    2008-01-01

    Steady-state visual evoked potentials (SSVEPs) are oscillating components of the electroencephalogram (EEG) that are detected over the occipital areas, having frequencies corresponding to visual stimulus frequencies. SSVEPs have been demonstrated to be reliable control signals for operating a brain-computer interface (BCI). This study uses offline analyses to investigate the characteristics of SSVEP harmonic amplitude and phase coupling and the impact of using this information to construct a matched filter for continuously tracking the signal.

  10. Topographic mapping of single sweep evoked potentials in the brain.

    PubMed

    Liberati, D; DiCorrado, S; Mandelli, S

    1992-09-01

    Single trial analysis of brain-evoked potentials via stochastic parametric identification and filtering is here extended to multichannel recordings, leading to the topographic mapping of the brain activity elicited by a single stimulus, instead of the usual averaged mapping. The temporal dynamics of the subsequent sweeps in the protocol of a neurophysiologic experiment can thus be recovered and quantified also on its spatial characteristic.

  11. The electroretinogram and visual evoked potential of freely moving rats.

    PubMed

    Szabó-Salfay, O; Pálhalmi, J; Szatmári, E; Barabás, P; Szilágyi, N; Juhász, G

    2001-09-01

    The vascularised rat retina could be one of the most useful experimental objects in visual neuroscience to understand human visual physiological and pathological processes. We report here on a new method of implantation for studying the visual system of freely moving rats that provides a rat model for simultaneous recording at corneal and cortical level and is stable enough to record for months. We implanted light emitting diodes onto the skull behind the eyeball to stimulate the eye with flashes and to light adapt the retina with constant light levels. A multistrand, stainless steel, flexible fine wire electrode placed on the eyeball was used for electroretinogram recording and screw electrodes (left/right visual and parietal cortical) were used to record the visual evoked potential and the electroencephalogram. In the present report we focus on the new method of implantation for recording the corneal flash electroretinogram of normal, freely moving rats simultaneously with the visual evoked cortical potential showing examples in various visual experiments. We also introduce a program for retinogram and visual evoked potential analysis, which defines various measures (latencies, areas, amplitudes, and durations) and draw attention to the benefits of this method for those involved in visual, functional genomic, pharmacological, and human ophthalmologic research.

  12. Cervical and ocular vestibular evoked myogenic potentials in Behcet's disease.

    PubMed

    Bayram, Ali; Doğan, Murat; Koç, Ali; Kalkan, Mehmet; Akçadağ, Alper; Özcan, İbrahim

    2015-01-01

    To investigate vestibular evoked myogenic potentials combined with audiologic status in Behcet's disease (BD) and to compare the results with normal healthy subjects. Cervical vestibular evoked myogenic potential (cVEMP) test, ocular vestibular evoked myogenic potential (oVEMP) test, Dix-Hallpike test, conventional pure tone audiometry (cPTA) and high frequency audiometry (HFA), and 226 and 1000Hz tympanometry were performed to each subject of the study. Cranial magnetic resonance imaging (MRI) with contrast enhancement was also performed to evaluate the central nervous system (CNS) in patients with BD. VEMP parameters including the mean peak latencies of p13-n23 and n10-p15, AR values and thresholds were not statistically different both in cVEMP and oVEMP between the BD and control groups. Except for 250Hz, mean audiological thresholds were significantly higher in the BD group. Five of the 20 patients had pathological cranial MRI findings that may be compatible with central nervous system involvement. To our knowledge, the present study is the first report investigating oVEMP and cVEMP responses combined with MRI findings in patients with BD. The presence of high frequency hearing loss is a common finding in BD and HFA may help early detection of hearing loss in patients with BD when combined with cPTA. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Perceptual learning of acoustic noise generates memory-evoked potentials.

    PubMed

    Andrillon, Thomas; Kouider, Sid; Agus, Trevor; Pressnitzer, Daniel

    2015-11-02

    Experience continuously imprints on the brain at all stages of life. The traces it leaves behind can produce perceptual learning [1], which drives adaptive behavior to previously encountered stimuli. Recently, it has been shown that even random noise, a type of sound devoid of acoustic structure, can trigger fast and robust perceptual learning after repeated exposure [2]. Here, by combining psychophysics, electroencephalography (EEG), and modeling, we show that the perceptual learning of noise is associated with evoked potentials, without any salient physical discontinuity or obvious acoustic landmark in the sound. Rather, the potentials appeared whenever a memory trace was observed behaviorally. Such memory-evoked potentials were characterized by early latencies and auditory topographies, consistent with a sensory origin. Furthermore, they were generated even on conditions of diverted attention. The EEG waveforms could be modeled as standard evoked responses to auditory events (N1-P2) [3], triggered by idiosyncratic perceptual features acquired through learning. Thus, we argue that the learning of noise is accompanied by the rapid formation of sharp neural selectivity to arbitrary and complex acoustic patterns, within sensory regions. Such a mechanism bridges the gap between the short-term and longer-term plasticity observed in the learning of noise [2, 4-6]. It could also be key to the processing of natural sounds within auditory cortices [7], suggesting that the neural code for sound source identification will be shaped by experience as well as by acoustics.

  14. Intraoperative Subcortical Fiber Mapping with Subcortico-Cortical Evoked Potentials.

    PubMed

    Enatsu, Rei; Kanno, Aya; Ohtaki, Shunya; Akiyama, Yukinori; Ochi, Satoko; Mikuni, Nobuhiro

    2016-02-01

    During brain surgery, there are difficulties associated with identifying subcortical fibers with no clear landmarks. We evaluated the usefulness of cortical evoked potentials with subcortical stimuli (subcortico-cortical evoked potential [SCEP]) in identifying subcortical fibers intraoperatively. We used SCEP to identify the pyramidal tract in 4 patients, arcuate fasciculus in 1 patient, and both in 2 patients during surgical procedures. After resection, a 1 × 4-electrode plate was placed on the floor of the removal cavity and 1-Hz alternating electrical stimuli were delivered to this electrode. A 4 × 5 recording electrode plate was placed on the central cortical areas to map the pyramidal tract and temporoparietal cortical areas for the arcuate fasciculus. SCEPs were obtained by averaging electrocorticograms time locked to the stimulus onset. The subcortical stimulation within 15 mm of the target fiber induced cortical evoked potentials in the corresponding areas, whereas the stimulation apart from 20 mm did not. Five patients showed transient worsening of neurologic symptoms after surgery. However, all patients recovered. SCEP was useful for identifying subcortical fibers and confirmed the preservation of these fibers. This technique is expected to contribute to the effectiveness and safety of resective surgery in patients with lesions close to eloquent areas. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Visual Evoked Potentials in Infants With Diffuse Periventricular Leukomalacia.

    PubMed

    Carbajal-Valenzuela, Cintli Carolina; Santiago-Rodríguez, Efraín; Harmony, Thalía; Fernández-Bouzas, Antonio

    2014-10-01

    Periventricular leukomalacia (PVL) is characterized by necrosis of the cerebral white matter in the dorsolateral portions of the lateral ventricles. PVL causes motor, sensory, and cognitive deficits. The aim of this study was to analyze the conduction characteristics of the visual pathway in infants with diffuse PVL using visual evoked potentials (VEPs). We studied 11 healthy infants (mean age 3.3 ± 1.3 months) and 17 with diffuse PVL (mean age 2.9 ± 0.8 months and mean gestational age 31.9 ± 3.1 weeks). The N75, P100, and N135 wave latencies; the interwave N75-P100 and P100-N135 latencies; and the N75-P100 and P100-N135 amplitudes were measured in the occipital leads. VEPs were recorded during binocular stimulation at an angle of 120' from the Fz-Oz lead. Healthy children had mean N75, P100, and N135 wave latencies of 84.4 ± 5.8, 143.4 ± 30.6 and 222.9 ± 40.4 ms, respectively. The mean interwave N75-P100 and P100-N135 latencies were 59.0 ± 28.6 and 79.5 ± 13.6 ms, respectively. Compared with the healthy group, infants with PVL had longer N75 and N135 latencies at 92.3 ± 15.3 (P = .05) and 265.0 ms ± 60.3 (P = .05), respectively. The interwave latency P100-N135 (105.5 ± 29.1 ms; P = .017) was longer in children with PVL than in healthy infants. Infants with diffuse PVL had mild alterations in their N75, P100 and, particularly, their N135 latencies. These increases in P100-N135 interwave latencies could be because of damage to the geniculocortical pathways and V2-V3 networks. © EEG and Clinical Neuroscience Society (ECNS) 2014.

  16. Is the movement-evoked potential mandatory for movement execution? A high-resolution EEG study in a deafferented patient.

    PubMed

    Kristeva, Rumyana; Chakarov, Vihren; Wagner, Michael; Schulte-Mönting, Jürgen; Hepp-Reymond, M-C

    2006-06-01

    During simple self-paced index finger flexion with and without visual feedback of the finger, we compared the movement-evoked potentials of the completely deafferented patient GL with those of 7 age-matched healthy subjects. EEG was recorded from 58 scalp positions, together with the electromyogram (EMG) from the first dorsal interosseous muscle and the movement trace. We analyzed the movement parameters and the contralateral movement-evoked potential and its source. The patient performed the voluntary movements almost as well as the controls in spite of her lack of sensory information from the periphery. In contrast, the movement-evoked potential was observed only in the controls and not in the patient. These findings clearly demonstrate that the movement-evoked potential reflects cutaneous and proprioceptive feedback from the moving part of the body. They also indicate that in absence of sensory peripheral input the motor control switches from an internal "sensory feedback-driven" to a "feedforward" mode. The role of the sensory feedback in updating the internal models and of the movement-evoked potential as a possible cortical correlate of motor awareness is discussed.

  17. Determination of sources using brain-evoked potential maps

    NASA Astrophysics Data System (ADS)

    Amir, Avner; Jewett, Don L.

    1993-08-01

    Methods to localize the sources of Brain Evoked Potential Maps based on modeling of the sources as point dipoles have been widely used for more than twenty years. Such methods still lack a basic theory which can answer questions regarding the resolution and uniqueness of the results in the context of a realistic head model, with no a prior restrictions on the sources. In the first part of the paper we present simple physical models for the origin of far-field potentials associated with the auditory and somatosensory systems. An action potential travels along a straight axon can only produce a quadrupole field at far distances. We show that the far field potentials must originate when the action potential passes through a bent axon or through changes in the conductivities or in the external boundaries of the volume conductor surrounding the axon. We discuss the question of uniqueness of the solution for the 'inverse problem' of evoked potentials. This problem involved the reconstruction of the location and pattern of activity of the neuronal generators in the brain, given the map of the scalp electric potentials. We show that in a head shape with a realistic geometry spatially distinct points, line or open surface generators cannot create the same scalp potential map. The same applies to two non-overlapping generators occupying finite volumes.

  18. Evoked potential application to study of echolocation in cetaceans

    NASA Astrophysics Data System (ADS)

    Supin, Alexander Ya.; Nactigall, Paul E.; Pawloski, Jeffrey; Au, Whitlow W. L.

    2002-05-01

    The evoked-potential (EP) method is effective in studies of hearing capabilities of cetaceans. However, until now EP studies in cetaceans were performed only in conditions of passive hearing by recording EP to external stimuli. Can this method be applied to study active echolocation in odontocetes? To answer this question, auditory brainstem evoked responses (ABR) were recorded in a false killer whale while the animal echolocated a target within an experiment in which the animal reported the target present or absent. The ABR collection was triggered by echolocation clicks. In these conditions, the recorded ABR pattern contained a duplicate set of waves. A comparison of ABR wave delays recorded during echolocation with those recorded during regular external stimulation has shown that the first set of waves is a response to the emitted click whereas the second one is a response to the echo. Both responses, to the emitted click and to the echo, were of comparable amplitude in spite of the intensity difference of these two sounds of more than 40 dB near the animal's head. This finding indicates some mechanisms releasing responses to echoes from masking by loud emitted clicks. The evoked-potential method may be productive to investigate these mechanisms.

  19. Polarity stimulation effects on brainstem auditory evoked potentials.

    PubMed

    Lima, Janaina Patricio de; Alvarenga, Kátia de Freitas; Foelkel, Tábata Pierini; Monteiro, Camila Zotelli; Agostinho, Raquel Sampaio

    2008-01-01

    Brainstem Auditory Evoked Potentials are considered exogenous potentials, that is, the responses obtained are highly dependent upon the characteristic of the stimulus used to evoke them. To investigate the influence of the click stimulus polarity in the study of Brainstem Evoked Response Audiometry (BERA) at different intensities, using insertion-canal earphones. Clinical. 33 individuals, aged between 18 and 28, with no auditory alteration were submitted to BERA testing, with click stimulus on the rarefaction, condensation and alternate polarities, in different intensities. The absolute latencies of the V wave proved to be lower in the rarefaction polarity when compared to the others and, at 80 dBnHL, there was a significant difference between rarefaction and the other polarities for interpeak latencies III-V and I-V. There was a high correlation between the condensation and alternating polarities for absolute and interpeak latencies at 80 dBnHL. the click stimulus polarity has a significant influence on BERA. In the routine use of the TDH 39 earphone, with alternating polarity, we suggest that condensation polarity is more adequate for standardized comparison purposes, due to the higher similarity of the latencies found in this insertion earphone study.

  20. Dexmedetomidine Does Not Affect Evoked Potentials During Spine Surgery.

    PubMed

    Rozet, Irene; Metzner, Julia; Brown, Marcia; Treggiari, Miriam M; Slimp, Jefferson C; Kinney, Greg; Sharma, Deepak; Lee, Lorri A; Vavilala, Monica S

    2015-08-01

    The effect of dexmedetomidine on evoked potentials (EPs) has not been elucidated. We aimed to investigate the effect of dexmedetomidine on somatosensory, motor, and visual EPs. After IRB approval, 40 adult patients scheduled for elective spine surgery using total IV anesthesia with propofol and remifentanil were randomly assigned to receive either dexmedetomidine (n = 20) or placebo (n = 20) in a double-blind, placebo-controlled trial. After obtaining informed consent, positioning, and baseline EPs recording, patients were randomly assigned to either IV dexmedetomidine 0.6 μg/kg infused over 10 minutes, followed by 0.6 μg/kg/h, or a corresponding volume of IV normal saline (placebo). EP measures at 60 ± 30 minutes after initiation of study drug were defined as T1 and at 150 ± 30 minutes were defined as T2. Changes from baseline to T1 (primary end point) and from baseline to T2 (secondary end point) in EP latencies (milliseconds) and amplitudes (microvolts) were compared between groups. Data presented as mean ± SD (95% confidence interval). Data from 40 patients (dexmedetomidine: n = 20; age, 54 ± 3 years; 10 males; placebo: n = 20; age, 52 ± 2 years; 5 males) were analyzed. There was no difference between dexmedetomidine versus placebo groups in primary end points: change of somatosensory EPs at T1, latency: 0.01 ± 1.3 (-0.64, 0.65) vs 0.01 ± 1.3 (-0.64, 0.65), P = 0.43 (-1.24, 0.45); amplitude: 0.03 ± 0.14 (-0.06, 0.02) vs -0.01 ± 0.13 (-0.07, 0.05), P = 0.76 (-0.074, 0.1); motor EPs amplitude at T1: 65.1 ± 194.8 (-35, 165; n = 18) vs 109.2 ± 241.4 (-24, 243; n = 16), P = 0.57 (-113.5, 241.57); visual EPs at T1 (right eye), amplitude: 2.3 ± 3.6 (-0.4, 5.1; n = 11) vs 0.3 ± 6.0 (-3.3, 3.9; n = 16), P = 0.38 (-6.7, 2.6); latency N1: 2.3 ± 3.6 (-0.4, 5.1) vs 0.3 ± 6.0 (-3.3, 3.9), P = 0.38 (-6.7, 2.6); latency P1: -1.6 ± 13.4 (-11.9, 8.7) vs -1.4 ± 8.1 (-6.3, 3.5), P = 0.97 (-9.3, 9.7) or secondary end points. There were no differences between

  1. The Efficacy of Intraoperative Neurophysiological Monitoring Using Transcranial Electrically Stimulated Muscle-evoked Potentials (TcE-MsEPs) for Predicting Postoperative Segmental Upper Extremity Motor Paresis After Cervical Laminoplasty

    PubMed Central

    Manabe, Hideki; Izumi, Bunichiro; Tanaka, Hiroyuki; Kawai, Kazumi; Tanaka, Nobuhiro

    2016-01-01

    Study Design: Prospective study. Objective: To investigate the efficacy of transcranial electrically stimulated muscle-evoked potentials (TcE-MsEPs) for predicting postoperative segmental upper extremity palsy following cervical laminoplasty. Summary of Background Data: Postoperative segmental upper extremity palsy, especially in the deltoid and biceps (so-called C5 palsy), is the most common complication following cervical laminoplasty. Some papers have reported that postoperative C5 palsy cannot be predicted by TcE-MsEPs, although others have reported that it can be predicted. Methods: This study included 160 consecutive cases that underwent open-door laminoplasty, and TcE-MsEP monitoring was performed in the biceps brachii, triceps brachii, abductor digiti minimi, tibialis anterior, and abductor hallucis. A >50% decrease in the wave amplitude was defined as an alarm point. According to the monitoring alarm, interventions were performed, which include steroid administration, foraminotomies, etc. Results: Postoperative deltoid and biceps palsy occurred in 5 cases. Among the 155 cases without segmental upper extremity palsy, there were no monitoring alarms. Among the 5 deltoid and biceps palsy cases, 3 had significant wave amplitude decreases in the biceps during surgery, and palsy occurred when the patients awoke from anesthesia (acute type). In the other 2 cases in which the palsy occurred 2 days after the operation (delayed type), there were no significant wave decreases. In all of the cases, the palsy was completely resolved within 6 months. Discussion: The majority of C5 palsies have been reported to occur several days after surgery, but some of them have been reported to occur immediately after surgery. Our results demonstrated that TcE-MsEPs can predict the acute type, whereas the delayed type cannot be predicted. Conclusions: A >50% wave amplitude decrease in the biceps is useful to predict acute-type segmental upper extremity palsy. Further examination

  2. The Electrically Evoked Compound Action Potential: From Laboratory to Clinic.

    PubMed

    He, Shuman; Teagle, Holly F B; Buchman, Craig A

    2017-01-01

    The electrically evoked compound action potential (eCAP) represents the synchronous firing of a population of electrically stimulated auditory nerve fibers. It can be directly recorded on a surgically exposed nerve trunk in animals or from an intra-cochlear electrode of a cochlear implant. In the past two decades, the eCAP has been widely recorded in both animals and clinical patient populations using different testing paradigms. This paper provides an overview of recording methodologies and response characteristics of the eCAP, as well as its potential applications in research and clinical situations. Relevant studies are reviewed and implications for clinicians are discussed.

  3. Evoked potentials are useful for diagnosis of neuromyelitis optica spectrum disorder.

    PubMed

    Ohnari, Keiko; Okada, Kazumasa; Takahashi, Toshiyuki; Mafune, Kosuke; Adachi, Hiroaki

    2016-05-15

    Neuromyelitis optica spectrum disorder (NMOSD) has been differentiated from relapsing-remitting multiple sclerosis (RRMS) by clinical, laboratory, and pathological findings, including the presence of the anti-aquaporin 4 antibody. Measurement of evoked potentials (EPs) is often used for the diagnosis of RRMS, although the possibility of applying EPs to the diagnosis of NMOSD has not been investigated in detail. Eighteen patients with NMOSD and 28 patients with RRMS were included in this study. The patients' neurological symptoms and signs were examined and their EPs were recorded. Characteristic findings were absence of visual evoked potentials and absence of motor evoked potentials in the lower extremities in patients with NMOSD, and a delay in these potentials in patients with RRMS. Most patients with NMOSD did not present abnormal subclinical EPs, whereas many patients with RRMS did. None of the patients with NMOSD showed abnormalities in auditory brainstem responses. NMOSD can be differentiated from RRMS by EP data obtained in the early stages of these diseases.

  4. Brainstem auditory evoked potentials in children with lead exposure.

    PubMed

    Alvarenga, Katia de Freitas; Morata, Thais Catalani; Lopes, Andrea Cintra; Feniman, Mariza Ribeiro; Corteletti, Lilian Cassia Bornia Jacob

    2015-01-01

    Earlier studies have demonstrated an auditory effect of lead exposure in children, but information on the effects of low chronic exposures needs to be further elucidated. To investigate the effect of low chronic exposures of the auditory system in children with a history of low blood lead levels, using an auditory electrophysiological test. Contemporary cross-sectional cohort. Study participants underwent tympanometry, pure tone and speech audiometry, transient evoked otoacoustic emissions, and brainstem auditory evoked potentials, with blood lead monitoring over a period of 35.5 months. The study included 130 children, with ages ranging from 18 months to 14 years, 5 months (mean age 6 years, 8 months ± 3 years, 2 months). The mean time-integrated cumulative blood lead index was 12 μg/dL (SD ± 5.7, range: 2.433). All participants had hearing thresholds equal to or below 20 dBHL and normal amplitudes of transient evoked otoacoustic emissions. No association was found between the absolute latencies of waves I, III, and V, the interpeak latencies I-III, III-V, and I-V, and the cumulative lead values. No evidence of toxic effects from chronic low lead exposures was observed on the auditory function of children living in a lead contaminated area. Copyright © 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  5. Evoked potentials in the management of patients with cochlear implants: research and clinical applications.

    PubMed

    Kileny, Paul R

    2007-04-01

    Evoked potential measures are integral to the treatment of patients with cochlear implants. In particular, these techniques are useful in the management of the pediatric patient. This brief report describes three categories of evoked potentials including clinical and research examples: electrically evoked auditory brain stem responses with transtympanic stimulation, middle-latency responses with cochlear implant stimulation, and cognitive evoked potentials elicited by speech stimuli.

  6. Auditory evoked potential could reflect emotional sensitivity and impulsivity

    PubMed Central

    Kim, Ji Sun; Kim, Sungkean; Jung, Wookyoung; Im, Chang-Hwan; Lee, Seung-Hwan

    2016-01-01

    Emotional sensitivity and impulsivity could cause interpersonal conflicts and neuropsychiatric problems. Serotonin is correlated with behavioral inhibition and impulsivity. This study evaluated whether the loudness dependence of auditory evoked potential (LDAEP), a potential biological marker of central serotonergic activity, could reflect emotional sensitivity and impulsivity. A total of 157 healthy individuals were recruited, who performed LDAEP and Go/Nogo paradigms during electroencephalogram measurement. Barratt impulsivity scale (BIS), Conners’ Adult ADHD rating scale (CAARS), and affective lability scale (ALS) were evaluated. Comparison between low and high LDAEP groups was conducted for behavioural, psychological, and event-related potential (ERP) measures. The high LDAEP group showed significantly increased BIS, a subscale of the CAARS, ALS, and false alarm rate of Nogo stimuli compared to the low LDAEP group. LDAEP showed significant positive correlations with the depression scale, ALS scores, subscale of the CAARS and Nogo-P3 amplitude. In the source activity of Nogo-P3, the cuneus, lingual gyrus, and precentral gyrus activities were significantly increased in the high LDAEP group. Our study revealed that LDAEP could reflect emotional sensitivity and impulsivity. LDAEP, an auditory evoked potential could be a useful tool to evaluate emotional regulation. PMID:27910865

  7. Short latency vestibular evoked potentials in the chicken embryo

    NASA Technical Reports Server (NTRS)

    Jones, S. M.; Jones, T. A.

    1996-01-01

    Electrophysiological responses to pulsed linear acceleration stimuli were recorded in chicken embryos incubated for 19 or 20 days (E19/E20). Responses occurred within the first 16 ms following the stimulus onset. The evoked potentials disappeared following bilateral labyrinthectomy, but persisted following cochlear destruction alone, thus demonstrating that the responses were vestibular. Approximately 8 to 10 response peaks could be identified. The first 4 positive and corresponding negative components (early peaks with latencies < 6.0 ms) were scored and latencies and amplitudes quantified. Vestibular response latencies were significantly longer (P < 0.01) and amplitudes significantly smaller (P < 0.001) than those observed in 2-week-old birds. Mean response threshold for anesthetized embryos was -15.9dBre 1.0 g/ms, which was significantly higher (P < 0.03) than those observed in 2-week-old birds (-23.0dBre 1.0 g/ms). Latency/intensity functions (that is, slopes) were not significantly different between embryos and 2-week-old animals, but amplitude/intensity functions for embryos were significantly shallower than those for 2-week-old birds (P < 0.001). We presume that these differences reflect the refinement of sensory function that occurs following 19 to 20 days of incubation. The recording of vestibular evoked potentials provides an objective, direct and noninvasive measure of peripheral vestibular function in the embryo and, as such, the method shows promise as an investigative tool. The results of the present study form the definitive basis for using vestibular evoked potentials in the detailed study of avian vestibular ontogeny and factors that may influence it.

  8. Short latency vestibular evoked potentials in the chicken embryo

    NASA Technical Reports Server (NTRS)

    Jones, S. M.; Jones, T. A.

    1996-01-01

    Electrophysiological responses to pulsed linear acceleration stimuli were recorded in chicken embryos incubated for 19 or 20 days (E19/E20). Responses occurred within the first 16 ms following the stimulus onset. The evoked potentials disappeared following bilateral labyrinthectomy, but persisted following cochlear destruction alone, thus demonstrating that the responses were vestibular. Approximately 8 to 10 response peaks could be identified. The first 4 positive and corresponding negative components (early peaks with latencies < 6.0 ms) were scored and latencies and amplitudes quantified. Vestibular response latencies were significantly longer (P < 0.01) and amplitudes significantly smaller (P < 0.001) than those observed in 2-week-old birds. Mean response threshold for anesthetized embryos was -15.9dBre 1.0 g/ms, which was significantly higher (P < 0.03) than those observed in 2-week-old birds (-23.0dBre 1.0 g/ms). Latency/intensity functions (that is, slopes) were not significantly different between embryos and 2-week-old animals, but amplitude/intensity functions for embryos were significantly shallower than those for 2-week-old birds (P < 0.001). We presume that these differences reflect the refinement of sensory function that occurs following 19 to 20 days of incubation. The recording of vestibular evoked potentials provides an objective, direct and noninvasive measure of peripheral vestibular function in the embryo and, as such, the method shows promise as an investigative tool. The results of the present study form the definitive basis for using vestibular evoked potentials in the detailed study of avian vestibular ontogeny and factors that may influence it.

  9. Clinical application of vestibular evoked myogenic potential (VEMP).

    PubMed

    Murofushi, Toshihisa

    2016-08-01

    The author reviewed clinical aspects of vestibular evoked myogenic potentials (VEMPs). Now two types of VEMPs are available. The first one is cervical VEMP, which is recorded in the sternocleidomastoid muscle and predominantly reflects sacculo-collic reflex. The other is ocular VEMP, which is usually recorded below the lower eye lid and predominantly reflects utriculo-ocular reflex. VEMPs play important roles not only for assessment of common vestibular diseases but also for establishment of new clinical entities. Clinical application in Meniere's disease, vestibular neuritis, benign paroxysmal positional vertigo, vestibular migraine, idiopathic otolithic vertigo, and central vertigo/dizziness was reviewed. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  10. The division of attention and the human auditory evoked potential

    NASA Technical Reports Server (NTRS)

    Hink, R. F.; Van Voorhis, S. T.; Hillyard, S. A.; Smith, T. S.

    1977-01-01

    The sensitivity of the scalp-recorded, auditory evoked potential to selective attention was examined while subjects responded to stimuli presented to one ear (focused attention) and to both ears (divided attention). The amplitude of the N1 component was found to be largest to stimuli in the ear upon which attention was to be focused, smallest to stimuli in the ear to be ignored, and intermediate to stimuli in both ears when attention was divided. The results are interpreted as supporting a capacity model of attention.

  11. Enhancement Of Visual Evoked Potentials By Adaptive Processing

    NASA Astrophysics Data System (ADS)

    Wolf, W.; Appel, U.; Rauner, H.

    1982-11-01

    Transient evoked potentials (EP) are variations of the on-going electroencephalogram (EEG) in response to the application of sensory stimuli. Since their amplitudes are very small in comparison to the spontaneous EEG, signal extraction methods must be applied to them before their characteristics are measureable. Several signal ex-traction methods which are actually used in EP research are outlined, especially those showing an adaptive characteristic. As a further development, a new method is proposed which considers the on-going EEG preceding the stimulus application for the EP processing. The computational procedure will be described and some preliminary results are given.

  12. The division of attention and the human auditory evoked potential

    NASA Technical Reports Server (NTRS)

    Hink, R. F.; Van Voorhis, S. T.; Hillyard, S. A.; Smith, T. S.

    1977-01-01

    The sensitivity of the scalp-recorded, auditory evoked potential to selective attention was examined while subjects responded to stimuli presented to one ear (focused attention) and to both ears (divided attention). The amplitude of the N1 component was found to be largest to stimuli in the ear upon which attention was to be focused, smallest to stimuli in the ear to be ignored, and intermediate to stimuli in both ears when attention was divided. The results are interpreted as supporting a capacity model of attention.

  13. Evaluation of breast sensibility using dermatomal somatosensory evoked potentials.

    PubMed

    DelVecchyo, Carlos; Caloca, Jaime; Caloca, Jaime; Gómez-Jauregui, Jesica

    2004-06-01

    This study was undertaken to prospectively evaluate breast sensibility before and after reduction mammaplasty with a new, objective, and quantitative neurophysiologic method based on the anatomic knowledge of breast innervation and the congruent areas of dermatomal maps. An innovative application of dermatomal somatosensory evoked potentials was used to study the breast regions of 42 healthy women, bilaterally. The areas stimulated in each breast were the superior quadrant, the nipple-areola complex and the medial and lateral quadrants, and the inferior quadrant; these areas correspond to T3, T4, and T5 dermatomes, respectively, following the accepted concepts of segmentary innervation of the skin. The two groups of 21 patients each were formed according to breast size: group I comprised small-breasted, unoperated controls (brassiere cup size A or B); group II comprised macromastia patients (brassiere cup size C or greater) who presented to a general plastic surgery department for breast reduction surgery. First the authors established the normal range of latency and amplitude in the dermatomal somatosensory evoked potentials for the five areas stimulated in patients with small breasts and compared these parameters with those obtained from patients with macromastia. Then, after the macromastia patients underwent reduction mammaplasty using the McKissock technique, the authors compared the postoperative sensory values with their own preoperative values and with those from the small-breasted group. Using dermatomal somatosensory evoked potentials, they found that small breasts were statistically more sensitive than large breasts, which concurs with studies in the literature that use other methods to evaluate breast sensibility. They also found that after breast reduction, the macromastia patients presented statistically significant improvement in breast sensibility in relation to their own preoperative latency and amplitude values, with no statistical difference in

  14. A Nonlinear Regression Procedure for Evoked Potential Data Analysis.

    DTIC Science & Technology

    1985-06-01

    XBAR+X (I) YBAR - YBAR +V (I) CONTINUE XBAR=XBAR/N VBAR= YBAR /N A-0. B-O. DO 10 I=19N C-X(I)-XBAR A=A+ Y (I)*C -36- B=B+C**2 *10 CONTINUE BSLP=A/B BI NT=YDAR...and duration of the latency effect following impact, the following exponential model was proposed: y = B + St + h(t)D + h(t)Aexp(t/T) + £(t) (1) where... y is the value of the shift in latency with respect to the preimpact baseline average evoked potential (AEP

  15. Visual evoked potentials and heart rate during white noise stimulation.

    PubMed

    Lucchese, F; Mecacci, L

    1999-03-01

    Visual evoked potentials (VEPs) were recorded in 12 adult participants as a function of the temporal frequency of a phase-reversed checkerboard, with or without a simultaneously presented white noise. During the VEP recordings also the pulse rate was measured. VEP amplitude changed as function of temporal frequency, but it was not affected by noise. Pulse rate was stable during the session without noise, but it increased during the white noise stimulation at high temporal frequencies. Heart acceleration might be associated to conditions when processing at low levels of visual sensitivity (high temporal frequencies) is furthermore disturbed by interfering stimulation (noise).

  16. Dissection of perceptual, motor and autonomic components of brain activity evoked by noxious stimulation.

    PubMed

    Piché, M; Arsenault, M; Rainville, P

    2010-06-01

    In the past two decades, functional brain imaging has considerably advanced our knowledge of cerebral pain processing. However, many important links are still missing in our understanding of brain activity in relation to the regulation of pain-related physiological responses. This fMRI study investigates the cerebral correlates of pain (rating), motor responses (RIII-reflex) and autonomic activity (skin conductance response; SCR) evoked by noxious electrical stimulation. Stimulus intensity was adjusted individually based on the RIII threshold to control for differences in peripheral processes and baseline spinal activation. Covariance analyses were used to reveal individual differences in brain activity uniquely associated with individual differences in pain, RIII and SCR. Shock-evoked activity in cingulate, medial orbitofrontal and parahippocampal regions predicted pain sensitivity. Moreover, lateral orbitofrontal and cingulate areas showed strong positive associations with individual differences in motor reactivity but negative associations with autonomic reactivity. Notably, individual differences in OFC activation was almost fully accounted by the combination of individual measures of autonomic and motor reactivity (R(2)=0.93). Additionally, trial-to-trial fluctuations of RIII-reflex and SCR (within-subjects) were proportional to shock-evoked responses in subgenual cingulate cortex (RIII), anterior insula (SCR) and midcingulate cortex (SCR and RIII). Together, these results confirm that individual differences in perceptual, motor, and autonomic components of pain reflect robust individual differences in brain activity. Furthermore, the brain correlates of trial-to-trial fluctuations in pain responses provide additional evidence for a partial segregation of sub-systems involved more specifically in the ongoing monitoring, and possibly the regulation, of pain-related motor and autonomic responses.

  17. A novel shape analysis technique for somatosensory evoked potentials.

    PubMed

    Agrawal, Gracee; Sherman, David; Thakor, Nitish; All, Angelo

    2008-01-01

    Somatosensory evoked potentials (SEP) have been shown to be an important electrophysiological measure to assess the integrity of the spinal cord. However the peaks in the SEP waveform are often undetectable due to low signal-to-noise (SNR) ratio. Sometimes they also become indistinct during injury when the SEP flattens. Hence time-domain analysis methods are often subject to errors, and need human-expert intervention. In this paper, we propose a new technique for analyzing the shape of the evoked potentials, in which slope information is obtained for the entire signal in specific time bins. Apart from solving the problems associated with present methods, this technique has an added advantage of analyzing the SEP signal as a whole rather than simply a few peaks. The efficacy of this technique was investigated on SEP signals recorded from 12 rats before and after contusion spinal cord injury at thoracic vertebra T8. The statistical analysis results revealed significant effect of injury to hindlimbs, whereas almost none to forelimbs. Thus, the results show high potential of this technique to differentiate between normal and injured spinal cord.

  18. Influence of stimulation intensity on paired-pulse suppression of human median nerve somatosensory evoked potentials.

    PubMed

    Gatica Tossi, Mario A; Lillemeier, Ann-Sophie; Dinse, Hubert R

    2013-06-19

    Paired-pulse stimulation, the application of two stimuli in close succession, is a useful tool to investigate cortical excitability. Suppression of the second response after short interstimulus intervals characterizes paired-pulse behavior. Although paired-pulse suppression is often studied as a marker of cortical excitability in humans, little is known about the influence of stimulation intensity on paired-pulse suppression. To systematically explore the effect of stimulus intensity on paired-pulse suppression of median nerve somatosensory evoked potentials (MNSEPs), we recorded single-pulse or paired-pulse MNSEPs in healthy volunteers using stimulation intensities ranging from the sensory threshold to 1.2 times the motor threshold using interstimulus intervals of 10, 30, and 100 ms. Of the various somatosensory evoked potential components, only the N20-P25 component showed an effect of intensity, where higher intensities resulted in stronger paired-pulse suppression. However, when only intermediate intensities were considered, paired-pulse suppression was not or only weakly influenced. Our data suggest that stimulation intensity in contrast to single pulse-evoked MNSEPs has only a weak influence on the paired-pulse suppression of early MNSEPs. Paired-pulse suppression is believed to arise from inhibition generated by intracortical networks. The lack of intensity dependence within the range tested can be considered as a step toward creating invariance against fluctuations of stimulus intensity. Thus, intracortical computations as apparent in paired-pulse behavior might be characterized by different properties compared with feed-forward processing.

  19. A joint sparse representation-based method for double-trial evoked potentials estimation.

    PubMed

    Yu, Nannan; Liu, Haikuan; Wang, Xiaoyan; Lu, Hanbing

    2013-12-01

    In this paper, we present a novel approach to solving an evoked potentials estimating problem. Generally, the evoked potentials in two consecutive trials obtained by repeated identical stimuli of the nerves are extremely similar. In order to trace evoked potentials, we propose a joint sparse representation-based double-trial evoked potentials estimation method, taking full advantage of this similarity. The estimation process is performed in three stages: first, according to the similarity of evoked potentials and the randomness of a spontaneous electroencephalogram, the two consecutive observations of evoked potentials are considered as superpositions of the common component and the unique components; second, making use of their characteristics, the two sparse dictionaries are constructed; and finally, we apply the joint sparse representation method in order to extract the common component of double-trial observations, instead of the evoked potential in each trial. A series of experiments carried out on simulated and human test responses confirmed the superior performance of our method.

  20. Prematurely Delivered Rats Show Improved Motor Coordination During Sensory-evoked Motor Responses Compared to Age-matched Controls

    PubMed Central

    Roberto, Megan E.; Brumley, Michele R.

    2014-01-01

    The amount of postnatal experience for perinatal rats was manipulated by delivering pups one day early (postconception day 21; PC21) by cesarean delivery and comparing their motor behavior to age-matched controls on PC22 (the typical day of birth). On PC22, pups were tested on multiple measures of motor coordination: leg extension response (LER), facial wiping, contact righting, and fore- and hindlimb stepping. The LER and facial wiping provided measures of synchronous hind- and forelimb coordination, respectively, and were sensory-evoked. Contact righting also was sensory-evoked and provided a measure of axial coordination. Stepping provided a measure of alternated forelimb and hindlimb coordination and was induced with the serotonin receptor agonist quipazine. Pups that were delivered prematurely and spent an additional day in the postnatal environment showed more bilateral limb coordination during expression of the LER and facial wiping, as well as a more mature righting strategy, compared to controls. These findings suggest that experience around the time of birth shapes motor coordination and the expression of species-typical behavior in the developing rat. PMID:24680729

  1. Prematurely delivered rats show improved motor coordination during sensory-evoked motor responses compared to age-matched controls.

    PubMed

    Roberto, Megan E; Brumley, Michele R

    2014-05-10

    The amount of postnatal experience for perinatal rats was manipulated by delivering pups one day early (postconception day 21; PC21) by cesarean delivery and comparing their motor behavior to age-matched controls on PC22 (the typical day of birth). On PC22, pups were tested on multiple measures of motor coordination: leg extension response (LER), facial wiping, contact righting, and fore- and hindlimb stepping. The LER and facial wiping provided measures of synchronous hind- and forelimb coordination, respectively, and were sensory-evoked. Contact righting also was sensory-evoked and provided a measure of axial coordination. Stepping provided a measure of alternated forelimb and hindlimb coordination and was induced with the serotonin receptor agonist quipazine. Pups that were delivered prematurely and spent an additional day in the postnatal environment showed more bilateral limb coordination during expression of the LER and facial wiping, as well as a more mature righting strategy, compared to controls. These findings suggest that experience around the time of birth shapes motor coordination and the expression of species-typical behavior in the developing rat.

  2. Abdominal acupuncture reduces laser-evoked potentials in healthy subjects.

    PubMed

    Pazzaglia, C; Liguori, S; Minciotti, I; Testani, E; Tozzi, A E; Liguori, A; Petti, F; Padua, L; Valeriani, M

    2015-09-01

    Acupuncture is known to reduce clinical pain, although the exact mechanism is unknown. The aim of the current study was to investigate the effect of acupuncture on laser-evoked potential amplitudes and laser pain perception. In order to evaluate whether abdominal acupuncture is able to modify pain perception, 10 healthy subjects underwent a protocol in which laser-evoked potentials (LEPs) and laser pain perception were collected before the test (baseline), during abdominal acupuncture, and 15 min after needle removal. The same subjects also underwent a similar protocol in which, however, sham acupuncture without any needle penetration was used. During real acupuncture, both N1 and N2/P2 amplitudes were reduced, as compared to baseline (p<0.01). The reduction lasted up to 15 min after needle removal. Furthermore, laser pain perception was reduced during real acupuncture, although the difference was marginally significant (p=0.06). Our results show that abdominal acupuncture reduces LEP amplitude in healthy subjects. Our results provide a theoretical background for the use of abdominal acupuncture as a therapeutic approach in the treatment of pain conditions. Future studies will have to be conducted in clinical painful syndromes, in order to confirm the analgesic effect of acupuncture in patients suffering from pain. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  3. Vestibular evoked myogenic potentials in patients with rheumatoid arthritis

    PubMed Central

    Heydari, Nahid; Hajiabolhassani, Fahimeh; Fatahi, Jamileh; Movaseghi, Shafieh; Jalaie, Shohreh

    2015-01-01

    Background: Rheumatoid arthritis (RA) is an autoimmune systemic disease. Most common autoimmune diseases are multisystem disorders that may also present with otological manifestations, and autoimmune inner ear disease accompanied by vestibular dysfunction. This study aimed to compare the vestibular function between RA patients and normal subjects using cervical vestibular evoked myogenic potentials (cVEMPs). Methods: In this cross- sectional study, 25patients with RA (19 female and 6 male: mean (±SD) age, 40.00 (±7.92) years) and 20 healthy subjects (15 female and 5 male: mean (±SD) age, 35.35 (±10.48) years) underwent cVEMPs, using 500 Hz-tone bursts at 95 dB nHL intensity level. Data were analyzed using independent sample t-test through SPSS software v. 16. Results: The mean peak latency of p13 was significantly higher in RA patients (p<0.001). The mean peak latency of n23 was significantly higher in patients in the left ear (p=0.03). Vestibular evoked myogenic potential (VEMP) responses were present in all (100%) of the participants. There were no significant differences in mean peak to peak amplitude and amplitude ratio between the two groups. Conclusion: According to the prolonged latency of VEMP responses in RA patients, lesions in the retrolabyrinthine, especially in the vestibulospinal tract are suspected. PMID:26478874

  4. Evoked trigeminal nerve potential in chronic trichloroethylene intoxication

    SciTech Connect

    Barret, L.; Arsac, P.; Vincent, M.; Faure, J.; Garrel, S.; Reymond, F.

    1982-06-01

    Results of a study of trigeminal nerve impairment resulting from trichloroethylene intoxication by the somatosensory-evoked potential method reveal three kinds of abnormalities: increased stimulation voltage, excessive latency delay with morphological abnormalities, and excessive graph amplitude. These abnormalities confirm clinical disturbance (hypesthesia of the trigeminal nerve area) and open debate about the real mechanism of trichloroethylene neurotoxicity. Industrial intoxication by solvents, particularly trichloroethylene, is common. We have conducted a study of 188 workers chronically exposed to trichloroethylene and have confirmed the selective neurological disturbances of this intoxication in the trigeminal nerve (20%) (3, 10). We utilized a new experimental method, developed for studies of chronic intoxications effecting the median nerve (5, 8), of recording the somatosensory evoked potential following stimulation of the trigeminal nerve (4, 6, 7). The workers in this study were selected following clinical evaluation of their facial sensitivity and trigeminal nerve reflexes. In this paper we present our preliminary results on 11 workers, 9 suffering effects of intoxication and 2 controls.

  5. Vestibular evoked myogenic potentials in multiple sclerosis patients.

    PubMed

    Versino, Maurizio; Colnaghi, Silvia; Callieco, Roberto; Bergamaschi, Roberto; Romani, Alfredo; Cosi, Vittorio

    2002-09-01

    Vestibular evoked myogenic potentials (VEMPs) are saccular responses to loud acoustic stimuli and are recordable from the sterno-cleido-mastoid muscle ipsilaterally to the stimulated ear. This study aimed to investigate VEMPs in patients suffering from multiple sclerosis (MS), and to compare these findings with both clinical and instrumental data. We recorded VEMPs from 70 MS patients, whose clinical data were retrospectively evaluated for the possible occurrence of: past and current (with respect to VEMP recording) brainstem and/or cerebellar symptoms; current brainstem and/or cerebellar signs. Sixty-five patients underwent brainstem auditory evoked potentials (BAEPs) recording; 63 of the same patients underwent saccadic eye movement recording and subjective visual vertical (SVV) evaluation. VEMPs were abnormal in 31%, BAEPs in 38% and SVV in 21% of the patients. Saccadic eye movements showed a possible brainstem dysfunction in 44.4% of the patients. There was no correlation between the occurrence of abnormalities and the technical means of detection. The same held true for correlations with clinical data, with the exception of the BAEPs; these proved to be more frequently abnormal in patients presenting at neurological examination with brainstem and/or cerebellar signs that were possibly related to the complaint of dizziness. VEMPs should be considered a useful complementary neurophysiological tool for the evaluation of brainstem dysfunction.

  6. Visual evoked potentials, reaction times and eye dominance in cricketers.

    PubMed

    Thomas, N G; Harden, L M; Rogers, G G

    2005-09-01

    Few studies have examined the physiology of cricket, including the difference in ability between batsmen to make controlled contact with a ball bowled at high speed. We therefore measured visual evoked potentials and choice reaction times with dominant eyes, non-dominant eyes, and both eyes together, in 15 elite batsmen and 10 elite bowlers (aged 20.9 SD 1.9 years) and 9 control subjects (aged 20.2 SD 1.5 years). The latency and amplitude of waves N70, P100 and N145 were determined for each visual evoked potential (VEP). In addition interpeak latencies and peak to peak amplitudes were measured. The subjects also completed a choice reaction test to a visual stimulus. We found that cricketers were not more likely to have crossed dominance (dominant eye contralateral to dominant hand) than controls. Cricketers had a faster latency for VEP wave N70 than controls (p=0.03). However reaction time was not different between cricketers and the control group. Across all subjects, in comparison to monocular testing, binocular testing led to a faster choice reaction time (p=0.02) and larger amplitudes of VEP wave N70 (p=0.01). Visual processing during the first 100(-1)50 ms of the balls flight together with binocular vision facilitates retinal activation in talented cricketers.

  7. Characteristics and clinical applications of ocular vestibular evoked myogenic potentials.

    PubMed

    Kantner, C; Gürkov, R

    2012-12-01

    Recently, ocular vestibular evoked myogenic potentials (oVEMPs) have been described and added to the neuro-otologic test battery as a new measure for the vestibulo-ocular reflex. oVEMPs represent extraocular muscle activity in response to otolith stimulation e.g. by air-conducted sound or bone-conducted vibration. In response to vestibular stimulation, electromyographic activity of the extraocular muscles can be recorded by means of surface electrodes placed beneath the contralateral eye. oVEMPs are likely to reflect predominantly utricular function, while the widely established cervical vestibular evoked myogenic potentials (cVEMPs) assess saccular function. Thus, measuring oVEMPs and cVEMPs in addition to caloric and head impulse testing provides further evaluation of the vestibular system and enables quick and cost-effective assessment of otolith function. This review summarizes the neurophysiological properties of oVEMPs, gives recommendations for recording conditions and discusses oVEMP alterations in various disorders of the vestibular system. With increasing insight into oVEMP characteristics in vestibular disorders, e.g. Menière's disease and superior semicircular canal dehiscence syndrome, oVEMPs are becoming a promising new diagnostic tool for evaluating utricular function. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Evoked brain potentials and disability in brain-damaged patients.

    PubMed

    Rappaport, M; Hall, K; Hopkins, K; Belleza, T; Berrol, S; Reynolds, G

    1977-08-01

    Various measures of evoked brain potential abnormality (EPA) were correlated with disability ratings (DR) for 35 brain-damaged patients. EPA data consisted of judgements of abnormality of ipsilateral, contralateral and bilateral responses to auditory and visual stimuli reflecting activity in the brain stem, subcortex and cortex. DR data were obtained from a scale developed for this study to quantize and categorize patients with a wide range of disabilities from coma to normal functioning. EPA scores based on visual and auditory cortical responses showed significantly positive correlations with degree of disability. Visual response correlation was .49, auditory .38 and combined visual and auditory .51. It was concluded that EPA measures can reflect disability independently of clinical information. They are useful in assessing brain function in general and, specifically, in assessing impairment of sensory function. The evoked potential technique was particularly useful in patients who were not able to participate fully in their own examination. There were indications that the technique may also be valuable in monitoring progress and in predicting clinical outcome in brain-damaged patients.

  9. Visual and brainstem auditory evoked potentials in children with obesity.

    PubMed

    Akın, Onur; Arslan, Mutluay; Akgün, Hakan; Yavuz, Süleyman Tolga; Sarı, Erkan; Taşçılar, Mehmet Emre; Ulaş, Ümit Hıdır; Yeşilkaya, Ediz; Ünay, Bülent

    2016-03-01

    The aim of our study is to investigate alterations in visual evoked potentials (VEP) and brainstem auditory evoked potentials (BAEP) in children with obesity. A total of 96 children, with a mean age of 12.1±2.0 years (range 9-17 years, 63 obese and 33 age and sex-matched control subjects) were included in the study. Laboratory tests were performed to detect insulin resistance (IR) and dyslipidemia. The latencies and amplitudes of VEP and BAEP were measured in healthy and obese subjects. The VEP P100, BAEP interpeak latency (IPL) I-III and IPL I-V averages of obese children were significantly longer than the control subjects. When the obese group was divided into two subgroups, those with IR and without IR, BAEP wave I, wave III and P100 wave latencies were found to be longer in the group with IR. A statistically significant correlation was observed between BAEP wave I latency, IPL I-V, IPL I-III and the homeostatic model assessment insulin resistance (HOMA IR) index and fasting insulin level. Our findings suggest that VEP and BAEP can be used to determine early subclinical on auditory and visual functions of obese children with insulin resistance. Copyright © 2015 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  10. Evoked-potential changes following discrimination learning involving complex sounds

    PubMed Central

    Orduña, Itzel; Liu, Estella H.; Church, Barbara A.; Eddins, Ann C.; Mercado, Eduardo

    2011-01-01

    Objective Perceptual sensitivities are malleable via learning, even in adults. We trained adults to discriminate complex sounds (periodic, frequency-modulated sweep trains) using two different training procedures, and used psychoacoustic tests and evoked potential measures (the N1-P2 complex) to assess changes in both perceptual and neural sensitivities. Methods Training took place either on a single day, or daily across eight days, and involved discrimination of pairs of stimuli using a single-interval, forced-choice task. In some participants, training started with dissimilar pairs that became progressively more similar across sessions, whereas in others training was constant, involving only one, highly similar, stimulus pair. Results Participants were better able to discriminate the complex sounds after training, particularly after progressive training, and the evoked potentials elicited by some of the sounds increased in amplitude following training. Significant amplitude changes were restricted to the P2 peak. Conclusion Our findings indicate that changes in perceptual sensitivities parallel enhanced neural processing. Significance These results are consistent with the proposal that changes in perceptual abilities arise from the brain’s capacity to adaptively modify cortical representations of sensory stimuli, and that different training regimens can lead to differences in cortical sensitivities, even after relatively short periods of training. PMID:21958655

  11. Evaluation of the neural function of nonhuman primates with spinal cord injury using an evoked potential-based scoring system

    PubMed Central

    Ye, Jichao; Ma, Mengjun; Xie, Zhongyu; Wang, Peng; Tang, Yong; Huang, Lin; Chen, Keng; Gao, Liangbin; Wu, Yanfeng; Shen, Huiyong; Zeng, Yuanshan

    2016-01-01

    Nonhuman primate models of spinal cord injury (SCI) have been widely used in evaluation of the efficacy and safety of experimental restorative interventions before clinical trials. However, no objective methods are currently available for the evaluation of neural function in nonhuman primates. In our long-term clinical practice, we have used evoked potential (EP) for neural function surveillance during operation and accumulated extensive experience. In the present study, a nonhuman primate model of SCI was established in 6 adult cynomologus monkeys through spinal cord contusion injury at T8–T9. The neural function before SCI and within 6 months after SCI was evaluated based on EP recording. A scoring system including somatosensory evoked potentials (SSEPs) and transcranial electrical stimulation-motor evoked potentials (TES-MEPs) was established for the evaluation of neural function of nonhuman primates with SCI. We compared the motor function scores of nonhuman primates before and after SCI. Our results showed that the EP below the injury level significantly changed during the 6 months after SCI. In addition, a positive correlation was identified between the EP scores and motor function. The EP-based scoring system is a reliable approach for evaluating the motor function changes in nonhuman primates with SCI. PMID:27629352

  12. Diagnostic use of dermatomal somatosensory-evoked potentials in spinal disorders: Case series

    PubMed Central

    Dikmen, Pinar Yalinay; Oge, A. Emre

    2013-01-01

    Objective/Context Dermatomal somatosensory-evoked potentials (dSEPs) may be valuable for diagnostic purposes in selected cases with spinal disorders. Design Reports on cases with successful use of dSEPs. Findings Cases 1 and 2 had lesions causing multiple root involvement (upper to middle lumbar region in Case 1 and lower sacral region in Case 2). Cystic lesions in both cases seemed to compress more than one nerve root, and stimulation at the center of the involved dermatomes in dSEPs helped to reveal the functional abnormality. Cases 3 and 4 had lesions involving the spinal cord with or without nerve root impairment. In Case 3, an magnetic resonance imaging (MRI)-verified lesion seemed to occupy a considerable volume of the lower spinal cord, causing only very restricted clinical sensory and motor signs. In Case 4, a cervical MRI showed a small well-circumscribed intramedullary lesion at right C2 level. All neurophysiological investigations were normal in the latter two patients (motor, tibial, and median somatosensory-evoked potentials in Case 3, and electromyography in both) except for the dSEPs. Conclusions Objectifying the presence and degree of sensory involvement in spinal disorders may be helpful for establishing diagnoses and in therapeutic decision-making. Valuable information could be provided by dSEPs in selected patients with multiple root or spinal cord involvement. PMID:24089995

  13. Band limited chirp stimulation in vestibular evoked myogenic potentials.

    PubMed

    Walther, Leif Erik; Cebulla, Mario

    2016-10-01

    Air conducted vestibular evoked myogenic potentials (VEMP) can be elicited by various low frequency and intense sound stimuli, mainly clicks or short tone bursts (STB). Chirp stimuli are increasingly used in diagnostic audiological evaluations as an effective means to obtain acoustically evoked responses in narrowed or extended frequency ranges. We hypothesized in this study that band limited chirp stimulation, which covers the main sensitivity range of sound sensitive otolithic afferents (around 500 Hz), might be useful for application in cervical and ocular VEMP to air conduction. For this purpose we designed a chirp stimulus ranging 250-1000 Hz (up chirp). The chirp stimulus was delivered with a stimulus intensity of 100 dB nHL in normal subjects (n = 10) and patients with otolith involvement (vestibular neuritis) (n = 6). Amplitudes of the designed chirp ("CW-VEMP-chirp, 250-1000 Hz") were compared with amplitudes of VEMPs evoked by click stimuli (0.1 ms) and a short tone burst (STB, 1-2-1, 8 ms, 500 Hz). CVEMPs and oVEMPs were detectable in 9 of 10 normal individuals. Statistical evaluation in healthy patients revealed significantly larger cVEMP and oVEMP amplitudes for CW-VEMP-chirp (250-1000 Hz) stimuli. CVEMP amplitudes evoked by CW-VEMP-chirp (250-1000 Hz) showed a high stability in comparison with click and STB stimulation. CW-VEMP-chirp (250-1000 Hz) showed abnormal cVEMP and oVEMP amplitudes in patients with vestibular neuritis, with the same properties as click and STB stimulated VEMPs. We conclude that the designed CW-VEMP-chirp (250-1000 Hz) is an effective stimulus which can be further used in VEMP diagnostic. Since a chirp stimulus can be easily varied in its properties, in particular with regard to frequency, this might be a promising tool for further investigations.

  14. Automatic denoising of single-trial evoked potentials.

    PubMed

    Ahmadi, Maryam; Quian Quiroga, Rodrigo

    2013-02-01

    We present an automatic denoising method based on the wavelet transform to obtain single trial evoked potentials. The method is based on the inter- and intra-scale variability of the wavelet coefficients and their deviations from baseline values. The performance of the method is tested with simulated event related potentials (ERPs) and with real visual and auditory ERPs. For the simulated data the presented method gives a significant improvement in the observation of single trial ERPs as well as in the estimation of their amplitudes and latencies, in comparison with a standard denoising technique (Donoho's thresholding) and in comparison with the noisy single trials. For the real data, the proposed method largely filters the spontaneous EEG activity, thus helping the identification of single trial visual and auditory ERPs. The proposed method provides a simple, automatic and fast tool that allows the study of single trial responses and their correlations with behavior.

  15. Automatic Parametrization of Somatosensory Evoked Potentials With Chirp Modeling.

    PubMed

    Vayrynen, Eero; Noponen, Kai; Vipin, Ashwati; Thow, X Y; Al-Nashash, Hasan; Kortelainen, Jukka; All, Angelo

    2016-09-01

    In this paper, an approach using polynomial phase chirp signals to model somatosensory evoked potentials (SEPs) is proposed. SEP waveforms are assumed as impulses undergoing group velocity dispersion while propagating along a multipath neural connection. Mathematical analysis of pulse dispersion resulting in chirp signals is performed. An automatic parameterization of SEPs is proposed using chirp models. A Particle Swarm Optimization algorithm is used to optimize the model parameters. Features describing the latencies and amplitudes of SEPs are automatically derived. A rat model is then used to evaluate the automatic parameterization of SEPs in two experimental cases, i.e., anesthesia level and spinal cord injury (SCI). Experimental results show that chirp-based model parameters and the derived SEP features are significant in describing both anesthesia level and SCI changes. The proposed automatic optimization based approach for extracting chirp parameters offers potential for detailed SEP analysis in future studies. The method implementation in Matlab technical computing language is provided online.

  16. Are hormones psychoactive? Evoked potential investigations in man.

    PubMed

    Saletu, B; Saletu, M; Herrmann, W M; Itil, T M

    1975-08-01

    The somatosensory evoked potential (SEP) of physically and mentally healthy male subjects was recorded before as well as 4 hours after administration of one single dose of placebo, cyproterone acetate (an antiandrogen), and mesterolone (an androgen). Quantitative evaluation of drug-induced changes in SEP latencies and amplitudes, which, when plotted in terms of t-values, result in the so-called "SEP profiles", did not demonstrate any significant alterations after placebo. Contrary to this, cyproterone acetate induced systematic and significant changes characterized by a latency increase in the early peaks and latency decrease in the late peaks of the SEP. Apart from the non-significant amplitude changes, such alterations were previously described by us as typical for drugs of the anxiolytic class. Mesterolone on the other hand, produced a significant latency decrease in the early part and a latency increase in the late part of the evoked response which was found to be typical for the SEP profiles of tricyclic antidepressants. The amplitude did not show any systematic changes. Based on step-wise discriminant analysis of these data we could significantly differentiate both hormones from placebo as well as from each other. A comparative analysis of low and high doses did not yield any significant differences between the two levels. It was concluded that both test substances have psychoactive properties; whereas cyproterone acetate reveals anxiolytic qualities, mesterolone exhibits antidepressant ones. These findings are discussed from the clinical as well as from the neurophysiological point of view.

  17. Maximally reliable spatial filtering of steady state visual evoked potentials.

    PubMed

    Dmochowski, Jacek P; Greaves, Alex S; Norcia, Anthony M

    2015-04-01

    Due to their high signal-to-noise ratio (SNR) and robustness to artifacts, steady state visual evoked potentials (SSVEPs) are a popular technique for studying neural processing in the human visual system. SSVEPs are conventionally analyzed at individual electrodes or linear combinations of electrodes which maximize some variant of the SNR. Here we exploit the fundamental assumption of evoked responses--reproducibility across trials--to develop a technique that extracts a small number of high SNR, maximally reliable SSVEP components. This novel spatial filtering method operates on an array of Fourier coefficients and projects the data into a low-dimensional space in which the trial-to-trial spectral covariance is maximized. When applied to two sample data sets, the resulting technique recovers physiologically plausible components (i.e., the recovered topographies match the lead fields of the underlying sources) while drastically reducing the dimensionality of the data (i.e., more than 90% of the trial-to-trial reliability is captured in the first four components). Moreover, the proposed technique achieves a higher SNR than that of the single-best electrode or the Principal Components. We provide a freely-available MATLAB implementation of the proposed technique, herein termed "Reliable Components Analysis".

  18. Vestibular evoked myogenic potentials: past, present and future.

    PubMed

    Rosengren, S M; Welgampola, M S; Colebatch, J G

    2010-05-01

    Since the first description of sound-evoked short-latency myogenic reflexes recorded from neck muscles, vestibular evoked myogenic potentials (VEMPs) have become an important part of the neuro-otological test battery. VEMPs provide a means of assessing otolith function: stimulation of the vestibular system with air-conducted sound activates predominantly saccular afferents, while bone-conducted vibration activates a combination of saccular and utricular afferents. The conventional method for recording the VEMP involves measuring electromyographic (EMG) activity from surface electrodes placed over the tonically-activated sternocleidomastoid (SCM) muscles. The "cervical VEMP" (cVEMP) is thus a manifestation of the vestibulo-collic reflex. However, recent research has shown that VEMPs can also be recorded from the extraocular muscles using surface electrodes placed near the eyes. These "ocular VEMPs" (oVEMPs) are a manifestation of the vestibulo-ocular reflex. Here we describe the historical development and neurophysiological properties of the cVEMP and oVEMP and provide recommendations for recording both reflexes. While the cVEMP has documented diagnostic utility in many disorders affecting vestibular function, relatively little is known as yet about the clinical value of the oVEMP. We therefore outline the known cVEMP and oVEMP characteristics in common central and peripheral disorders encountered in neuro-otology clinics.

  19. ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.

    EPA Science Inventory

    This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats

    " NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo.

    " The pattern evok...

  20. ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.

    EPA Science Inventory

    This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats

    " NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo.

    " The pattern evok...

  1. Assessment of visual disability using visual evoked potentials

    PubMed Central

    2012-01-01

    Background The purpose of this study is to validate the use of visual evoked potential (VEP) to objectively quantify visual acuity in normal and amblyopic patients, and determine if it is possible to predict visual acuity in disability assessment to register visual pathway lesions. Methods A retrospective chart review was conducted of patients diagnosed with normal vision, unilateral amblyopia, optic neuritis, and visual disability who visited the university medical center for registration from March 2007 to October 2009. The study included 20 normal subjects (20 right eyes: 10 females, 10 males, ages 9–42 years), 18 unilateral amblyopic patients (18 amblyopic eyes, ages 19–36 years), 19 optic neuritis patients (19 eyes: ages 9–71 years), and 10 patients with visual disability having visual pathway lesions. Amplitude and latencies were analyzed and correlations with visual acuity (logMAR) were derived from 20 normal and 18 amblyopic subjects. Correlation of VEP amplitude and visual acuity (logMAR) of 19 optic neuritis patients confirmed relationships between visual acuity and amplitude. We calculated the objective visual acuity (logMAR) of 16 eyes from 10 patients to diagnose the presence or absence of visual disability using relations derived from 20 normal and 18 amblyopic eyes. Results Linear regression analyses between amplitude of pattern visual evoked potentials and visual acuity (logMAR) of 38 eyes from normal (right eyes) and amblyopic (amblyopic eyes) subjects were significant [y = −0.072x + 1.22, x: VEP amplitude, y: visual acuity (logMAR)]. There were no significant differences between visual acuity prediction values, which substituted amplitude values of 19 eyes with optic neuritis into function. We calculated the objective visual acuity of 16 eyes of 10 patients to diagnose the presence or absence of visual disability using relations of y = −0.072x + 1.22 (−0.072). This resulted in a prediction reference of visual

  2. Peripheral neuropathy and visual evoked potential changes in workers exposed to n-hexane.

    PubMed

    Kutlu, Gulnihal; Gomceli, Yasemin B; Sonmez, Tolga; Inan, Levent E

    2009-10-01

    The aim of this study was to evaluate patients who had peripheral neuropathy and changes to their visual evoked responses resulting from exposure to n-hexane. Eighteen patients with acute or subacute neuropathy, who were working in a shoe factory, were investigated clinically and electrophysiologically. These evaluations were then repeated 9 months to 12 months after cessation of exposure to n-hexane. Results of the nerve conduction studies predominantly showed a decrease in motor and sensory conduction velocities. Between 9 and 12 months after cessation of exposure to n-hexane, 83.3% of patients had a complete clinical recovery. The electrophysiological studies also revealed improvement to the majority of motor and sensory nerve conduction velocities. The results of the visual evoked potential (VEP) studies were considered normal at admission, however, the P100 latencies at the 9-month to 12-month retest had improved (p < 0.05). As the abnormalities identified with clinical examination and nerve conduction studies, and the subclinical abnormalities revealed through VEP assessment, could be reversed after exposure to n-hexane had ceased, the clinical prognosis was usually good.

  3. The visual evoked potential in acute primary angle closure glaucoma.

    PubMed Central

    Mitchell, K. W.; Wood, C. M.; Howe, J. W.; Church, W. H.; Smith, G. T.; Spencer, S. R.

    1989-01-01

    Visual evoked potentials (VEPs) were elicited from 29 patients who had experienced a previous attack of acute primary angle closure glaucoma. The VEPs were shown to be abnormal in at least one of the measures (latency, amplitude, contrast threshold, or slope) in 72.4% of affected eyes, whereas only 41.4% indicated obvious optic nerve damage. It is notable that 48.1% of fellow eyes with no (known) history of acute pressure rise also showed some form of VEP abnormality. The possible pathophysiological mechanisms operating in both affected and fellow eyes are discussed. It is concluded that, despite the presence of possible artefactual influences, the results probably reflect the presence of primary angle closure glaucoma. PMID:2751978

  4. Psychiatric vulnerability, monoamine oxidase, and the average evoked potential.

    PubMed

    Haier, R J; Buchsbaum, M S; Murphy, D L; Gottesman, I I; Coursey, R D

    1980-03-01

    College students in two separate studies had platelet monoamine oxidase (MAO) activity determinations and average evoked potential (AEP) measurements taken. On the basis of Minnesota Muliphasic Personality Inventory (MMPI) or Research Diagnostic Criteria (RDC) evaluations, psychopathology, particularly affective disorder, was found to be more prevalent among both persons with the combination of low MAO activity and AEP augmenting and those with high MAO activity and AEP reducing. The same pattern is apparent whether students were selected for extremely high or low MAO activity (study 1) or for elevated or normal MMPI scores (study 2). Some psychiatric patient groups also show this pattern. An interactive model of sensation-seeking and sensory inhibition is presented.

  5. Visual evoked potentials and selective attention to points in space

    NASA Technical Reports Server (NTRS)

    Van Voorhis, S.; Hillyard, S. A.

    1977-01-01

    Visual evoked potentials (VEPs) were recorded to sequences of flashes delivered to the right and left visual fields while subjects responded promptly to designated stimuli in one field at a time (focused attention), in both fields at once (divided attention), or to neither field (passive). Three stimulus schedules were used: the first was a replication of a previous study (Eason, Harter, and White, 1969) where left- and right-field flashes were delivered quasi-independently, while in the other two the flashes were delivered to the two fields in random order (Bernoulli sequence). VEPs to attended-field stimuli were enhanced at both occipital (O2) and central (Cz) recording sites under all stimulus sequences, but different components were affected at the two scalp sites. It was suggested that the VEP at O2 may reflect modality-specific processing events, while the response at Cz, like its auditory homologue, may index more general aspects of selective attention.

  6. Spatial coincidence modulates interaction between visual and somatosensory evoked potentials.

    PubMed

    Schürmann, Martin; Kolev, Vasil; Menzel, Kristina; Yordanova, Juliana

    2002-05-07

    The time course of interaction between concurrently applied visual and somatosensory stimulation with respect to evoked potentials (EPs) was studied. Visual stimuli, either in the left or right hemifield, and electric stimuli to the left wrist were delivered either alone or simultaneously. Visual and somatosensory EPs were summed and compared to bimodal EPs (BiEP, response to actual combination of both modalities). Temporal coincidence of stimuli lead to sub-additive or over-additive amplitudes in BiEPs in several time windows between 75 and 275 ms. Additional effects of spatial coincidence (left wrist with left hemifield) were found between 75 and 300 ms and beyond 450 ms. These interaction effects hint at a temporo-spatial pattern of multiple brain areas participating in the process of multimodal integration.

  7. Laser-evoked potentials in primary headaches and cranial neuralgias.

    PubMed

    de Tommaso, Marina

    2008-09-01

    Using neurophysiological methods to explore nociceptive pathways may improve knowledge of the functional changes subtending pain processing in the different forms of headache and facial pain. Laser-evoked potentials (LEPs) are a reliable neurophysiological assay for the clinical assessment of pain syndromes. Reduced amplitude of LEPs seems to characterize trigeminal neuralgia and painful temporomandibular disorders, suggesting the neuropathic origin of pain. In tension-type headache, as well as in fibromyalgia, enhanced pericranial LEP amplitude suggests the psychogenic origin of pain. In migraine, a normal amplitude of basal LEPs with reduced habituation and altered attentive modulation seems to express a general dysfunction of cortical pain processing, which may also contribute, other than to predispose, to the persistence of migraine. LEPs may be employed in the clinical evaluation of the neurophysiological and psychophysiological aspects of pain in the different forms of headaches and facial pain to improve the therapeutic approach and provide an objective measure of treatment efficacy.

  8. [Lateralization in dissociated vertical deviation with flash visual evoked potentials].

    PubMed

    Suwa, K; Yagasaki, T; Awaya, S

    1996-08-01

    Lateralization, suggesting misrouting of optic nerve fibers in albinism, was examined by the flash visual evoked potentials (flash VEP) test in dissociated vertical deviation (DVD). Eighteen cases of DVD were studied and compared with 5 cases of X-recessive ocular albinism and 4 normal controls. Full-field monocular and binocular stimulation was employed with electroencepharograph electrodes on O1 and O2 (10/20 system), and the latency of P100 was statistically analysed with two-way analysis of variance. The difference in the P100 latency between contralateral and ipsilateral stimulation was significant (p < 0.05) in albinism, but not in DVD and normal controls. Therefore, DVD is probably not associated with misrouting of optic nerve fibers.

  9. Visual evoked potentials in neuromyelitis optica and its spectrum disorders.

    PubMed

    Ringelstein, Marius; Kleiter, Ingo; Ayzenberg, Ilya; Borisow, Nadja; Paul, Friedemann; Ruprecht, Klemens; Kraemer, Markus; Cohn, Eva; Wildemann, Brigitte; Jarius, Sven; Hartung, Hans-Peter; Aktas, Orhan; Albrecht, Philipp

    2014-04-01

    Optic neuritis (ON) is a key feature of neuromyelitis optica (NMO). Recently, NMO patients of predominantly Afro-Brazilian origin were evaluated by visual evoked potentials (VEPs) and showed marked amplitude reductions. Here, we analyzed VEPs in a predominantly Caucasian cohort, consisting of 43 patients with definite NMO, 18 with anti-aquaporin (AQP) 4 antibody-seropositive NMO spectrum disorders and 61 matched healthy controls. We found reduced amplitudes in only 12.3%, prolonged latencies in 41.9% and a lack of response in 14.0% of NMO eyes. Delayed P100 latencies in eyes without prior ON suggested this was a subclinical affection. The data indicate heterogenous patterns in NMO, warranting further investigation.

  10. Visual evoked potentials and selective attention to points in space

    NASA Technical Reports Server (NTRS)

    Van Voorhis, S.; Hillyard, S. A.

    1977-01-01

    Visual evoked potentials (VEPs) were recorded to sequences of flashes delivered to the right and left visual fields while subjects responded promptly to designated stimuli in one field at a time (focused attention), in both fields at once (divided attention), or to neither field (passive). Three stimulus schedules were used: the first was a replication of a previous study (Eason, Harter, and White, 1969) where left- and right-field flashes were delivered quasi-independently, while in the other two the flashes were delivered to the two fields in random order (Bernoulli sequence). VEPs to attended-field stimuli were enhanced at both occipital (O2) and central (Cz) recording sites under all stimulus sequences, but different components were affected at the two scalp sites. It was suggested that the VEP at O2 may reflect modality-specific processing events, while the response at Cz, like its auditory homologue, may index more general aspects of selective attention.

  11. Identification of diagnostic evoked response potential segments in Alzheimer's disease.

    PubMed

    Benvenuto, James; Jin, Yi; Casale, Malcolm; Lynch, Gary; Granger, Richard

    2002-08-01

    Evoked response potentials (ERPs) to brief flashes of light were analyzed for constituent features that could be used to distinguish individuals with Alzheimer's disease (AD, n = 15) from matched control subjects (n = 17). Statistical k nearest-neighbor methods distinguished AD from control with a maximum sensitivity of 29% and false alarm rate of 12%. The comparable sensitivity/false-alarm values for a statistical projection pursuit method and an extended projection pursuit method, which selectively identify discriminative features for classification, were 75%/18% and 100%/6%, respectively. The results demonstrate that combinations of selected ERP time segments across different electrodes contain signal features that discriminate AD from control subjects with high sensitivity and specificity.

  12. Auditory Evoked Potential Response and Hearing Loss: A Review

    PubMed Central

    Paulraj, M. P; Subramaniam, Kamalraj; Yaccob, Sazali Bin; Adom, Abdul H. Bin; Hema, C. R

    2015-01-01

    Hypoacusis is the most prevalent sensory disability in the world and consequently, it can lead to impede speech in human beings. One best approach to tackle this issue is to conduct early and effective hearing screening test using Electroencephalogram (EEG). EEG based hearing threshold level determination is most suitable for persons who lack verbal communication and behavioral response to sound stimulation. Auditory evoked potential (AEP) is a type of EEG signal emanated from the brain scalp by an acoustical stimulus. The goal of this review is to assess the current state of knowledge in estimating the hearing threshold levels based on AEP response. AEP response reflects the auditory ability level of an individual. An intelligent hearing perception level system enables to examine and determine the functional integrity of the auditory system. Systematic evaluation of EEG based hearing perception level system predicting the hearing loss in newborns, infants and multiple handicaps will be a priority of interest for future research. PMID:25893012

  13. Transient visually evoked potentials to sinusoidal gratings in optic neuritis.

    PubMed Central

    Plant, G T

    1983-01-01

    Transient visually evoked potentials (VEPs) to sinusoidal gratings over a range of spatial frequencies have been recorded in cases of optic neuritis. The use of the response to pattern onset in addition to the response to pattern reversal extended the range to higher spatial frequencies by up to two octaves. There was an increase in VEP delay and a greater degree of discrimination from a control group at higher spatial frequencies. This finding is discussed in the light of previous reports of luminance and checkerboard VEPs in demyelinating optic nerve disease. An attempt is made to relate amplitude changes in various VEP components to contrast sensitivity measurements in this group of patients. PMID:6663312

  14. Brainstem auditory evoked potentials in cattle sedated with xylazine

    PubMed Central

    Arai, Shozo

    2008-01-01

    This study examined the effect of sedation with xylazine on the brainstem auditory evoked potentials (BAEP) of cattle to determine whether sedation causes differences in waveform configuration, peak latencies, interpeak latencies, measurement time of the average count (2000 responses), and clinical signs. There were no significant differences between the sedation and no-sedation groups in peak latency of any stimulus intensities. In the sedation group, the baselines of waveforms were comparatively stabilized. Those in the no-sedation group were unstable, however, because the measurement can be influenced by excessive muscle movement. The present findings suggest that clinically, it is useful to use a sedative when measuring BAEP in cattle to control excessive movement of the cattle without influencing the peak latencies. PMID:18505193

  15. Visual evoked potential findings in Behcet's disease without neurological manifestations.

    PubMed

    Anlar, Omer; Akdeniz, Necmettin; Tombul, Temel; Calka, Omer; Bilgili, Serap G

    2006-03-01

    Behçet's disease (BD) is a chronic, recurrent multisystem inflammatory disorder firstly described by Turkish dermatologist Dr. Hulusi Behçet in 1937. The classic triad consists of recurrent oral and genital ulcerations and uveitis. The article presents the value of visual evoked potential findings of a series of 44 patients with BD without neurological manifestations seen at the Medical Hospital in Neurology and Dermatology clinics over the past 8 years. The mean latency value of positive peak P100 in BD patients was significantly delayed compared to that of control subjects (patients's mean: 105.6 ms in right eye and 107.7 ms in left eye; control subject's mean: 101.4 ms in right eye and 101.7 ms in left eye).

  16. Do evoked potentials contribute to the functional follow-up and clinical prognosis of multiple sclerosis?

    PubMed

    Giffroy, Xavier; Maes, Nathalie; Albert, Adelin; Maquet, Pierre; Crielaard, Jean-Michel; Dive, Dominique

    2017-03-01

    The clinical variability and complexity of multiple sclerosis (MS) challenges the individual clinical course prognostication. This study aimed to find out whether multimodal evoked potentials (EP) correlate with the motor components of multiple sclerosis functional composite (MSFCm) and predict clinically relevant motor functional deterioration. One hundred MS patients were assessed at baseline (T 0) and about 7.5 years later (T 1), with visual, somatosensory and motor EP and rated on the Expanded Disability Status Scale (EDSS) and the MSFCm, including the 9 Hole Peg Test and the Timed 25 Foot Walk (T25FW). The Spearman correlation coefficient (r S) was used to evaluate the cross-sectional and longitudinal relationship between EP Z scores and clinical findings. The predictive value of baseline electrophysiological data for clinical worsening (EDSS, 9-HPT, T25FW, MSFCm) during follow-up was assessed by logistic regression analysis. Unlike longitudinal correlations, cross-sectional correlations between EP Z scores and clinical outcomes were all significant and ranged between 0.22 and 0.67 (p < 0.05). The global EP Z score was systematically predictive of EDSS and MSFCm worsening over time (all p < 0.05). EP latency was a better predictor than amplitude, although weaker than latency and amplitude aggregation in the global EP Z score. The study demonstrates that EP numerical scores can be used for motor function monitoring and outcome prediction in patients with MS.

  17. Somatosensory evoked cerebral potentials (SSEP) in multiple sclerosis.

    PubMed

    Loncarević, Nedim; Tirić-Campara, Merita; Mulabegović, Nedzad

    2008-01-01

    Neurological findings are the main criteria for making the diagnosis of multiple sclerosis, including head and spine MRI, CSF findings and evoked potentials. Investigate and observe correlation in SSEP especially wave P22 in group of healthy examiners, as well on those suffering multiple sclerosis. Present Evoked potentials clinical application benefits in Multiple sclerosis diagnostic procedures used in Neurological Clinic, Clinical Center University of Sarajevo. EXAMINES AND METHODS: Examination is prospective and clinically applicable. Examination involved one hundred examinees in total, divided in two group where 50 examinees where confirmed with Multiple sclerosis diagnosis, and 50 others made up control group of healthy volunteers. Examination is made based on neurological findings, questionnaires for EP and MS, and SSEP done for all examinees. Statistical assessment is based upon percentage, standard deviation, Chi square test and Student t test. average age of patients in control group is 35.28, and at the same time 34.90 in experimental group and do not have statistical significance. In both group females were dominant gender and there was no statistical significance of gender ration between two group. Wave P22 was statistical significantly extended in group of MS diagnosed patients compared to the group of healthy examinees. our studies dominantly affected female gender. Studies presented statistically significant increase of SSEP abnormalities in MS diagnosed patients group compared to the group of healthy examinees, in term of extended latency of waves P22 as cortical responses. These figures shows significance of SSEP clinical use in MS diagnostically procedures, to additionally confirm definite diagnosis.

  18. Somatosensory evoked potentials predict neurolysis outcome in meralgia paraesthetica.

    PubMed

    Siu, Timothy L T; Chandran, K Nadana

    2004-01-01

    The role of somatosensory evoked potentials (SEP) in predicting the outcome of nerve entrapment syndrome following surgical release has not been fully verified. All patients included in our study had preoperative SEP recordings and had undergone neurolysis for treatment of meralgia paraesthetica by our senior author (KNC) between 1996 and 2000. The outcome of surgery was assessed 6 weeks after the procedure; follow up was continued at 3 month intervals if symptoms persisted. Telephone interviews were conducted to assess long-term results. Univariate and multivariate logistic regression analyses were used to establish the predictive value of side-to-side N1 and P1 latency differences in obtaining complete relief of symptoms following surgery. Twenty-four patients who had preoperative SEP recordings and had undergone neurolysis for meralgia paraesthetica were followed for 4.0 +/- 1.5 (SD) years. A prolonged side-to-side N1 latency difference (DeltaN1) was found to be significantly associated with complete relief of symptoms at about 6 weeks postoperatively, after adjustment for age, sex and duration of symptoms (OR, 1.75; CI, 1.03-2.96). Logistic regression identified a critical cut-off value of 8 ms (OR, 27.2; CI, 1.4-547.0). This association disappeared with longer follow up. Somatosensory evoked potentials provide significant data for prediction of good surgical outcome for meralgia paraesthetica. Re-evaluation of the diagnosis, adequate trial of conservative treatments and special attention to anomalous branches are recommended for patients with low preoperative DeltaN1 values.

  19. EEG, evoked potentials and pulsed Doppler in asphyxiated term infants.

    PubMed

    Julkunen, Mia K; Himanen, Sari-Leena; Eriksson, Kai; Janas, Martti; Luukkaala, Tiina; Tammela, Outi

    2014-09-01

    To evaluate electroencephalograms (EEG), evoked potentials (EPs) and Doppler findings in the cerebral arteries as predictors of a 1-year outcome in asphyxiated newborn infants. EEG and EPs (brain stem auditory (BAEP), somatosensory (SEP), visual (VEP) evoked potentials) were assessed in 30 asphyxiated and 30 healthy term infants during the first days (range 1-8). Cerebral blood flow velocities (CBFV) were measured from the cerebral arteries using pulsed Doppler at ∼24h of age. EEG, EPs, Doppler findings, symptoms of hypoxic ischemic encephalopathy (HIE) and their combination were evaluated in predicting a 1-year outcome. An abnormal EEG background predicted poor outcome in the asphyxia group with a sensitivity of 67% and 81% specificity, and an abnormal SEP with 75% and 79%, respectively. Combining increased systolic CBFV (mean+3SD) with abnormal EEG or SEP improved the specificity, but not the sensitivity. The predictive values of abnormal BAEP and VEP were poor. Normal EEG and SEP predicted good outcome in the asphyxia group with sensitivities from 79% to 81%. The combination of normal EEG, normal SEP and systolic CBFV<3SD predicted good outcome with a sensitivity of 74% and 100% specificity. Combining abnormal EEG or EPs findings with increased systolic CBFV did not improve prediction of a poor 1-year outcome of asphyxiated infants. Normal EEG and normal SEP combined with systolic CBFV<3SD at about 24 h can be valuable in the prediction of normal 1-year outcome. Combining systolic CBFV at 24 h with EEG and SEP examinations can be of use in the prediction of normal 1-year outcome among asphyxiated infants. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  20. Neurosurgical procedures, spinal nerve roots - one stage removal of thoracic dumb-bell tumor: role of spinal evoked potential.

    PubMed

    Srivastava, Dharmendra Kumar; Singh, Deepak; Tiwari, Bhuwan Chandra; Awasthi, Namarata; Hussain, Nuzhat

    2014-02-01

    We report a rare case of benign thoracic dumb-bell tumor in the upper posterior mediastinum, which was successfully removed by posterolateral thoracotomy and foraminotomy, using intraoperative monitoring of spinal motor-evoked potentials. This technique has many advantages including minimal morbidity and mortality, a single incision, one-step complete resection with adequate exposure, spinal stabilization, avoidance of laminectomy, nerve root identification, and good predicted postoperative function.

  1. Discharges of aortic and carotid sinus baroreceptors during spontaneous motor activity and pharmacologically evoked pressor interventions.

    PubMed

    Matsukawa, Kanji; Ishii, Kei; Kadowaki, Akito; Ishida, Tomoko; Idesako, Mitsuhiro; Liang, Nan

    2014-07-01

    Our laboratory has demonstrated that the cardiomotor component of aortic baroreflex is temporarily inhibited at the onset of spontaneous motor activity in decerebrate cats, without altering carotid sinus baroreflex. A reason for this dissociation may be attributed to a difference in the responses between aortic nerve activity (AoNA) and carotid sinus nerve activity (CsNA) during spontaneous motor activity. The stimulus-response curves of AoNA and CsNA against mean arterial blood pressure (MAP) were compared between the pressor interventions evoked by spontaneous motor activity and by intravenous administration of phenylephrine or norepinephrine, in which the responses in heart rate (HR) were opposite (i.e., tachycardia vs. baroreflex bradycardia), despite the identical increase in MAP of 34-40 mmHg. In parallel to the pressor response, mean AoNA and CsNA increased similarly by 78-81 and by 88 % of the baseline control, respectively, irrespective of whether the pressor response was evoked by spontaneous motor activity or by a pharmacological intervention. The slope of the stimulus-response curve of the mean AoNA became greater (P < 0.05) during spontaneous motor activity as compared to the pharmacological intervention. On the other hand, the stimulus-response curve of the mean CsNA and its slope were equal (P > 0.05) between the two pressor interventions. Furthermore, the slopes of the stimulus-response curves of both diastolic AoNA and CsNA (defined as the minimal value within a beat) exhibited a greater increase during spontaneous motor activity. All differences in the slopes of the stimulus-response curves were abolished by restraining HR at the intrinsic cardiac frequency. In conclusion, mean mass activities of both aortic and carotid sinus baroreceptors are able to encode the beat-by-beat changes in MAP not only at rest but also during spontaneous motor activity and spontaneous motor activity-related reduction of aortic baroreceptor activity is denied

  2. Recording Visual Evoked Potentials and Auditory Evoked P300 at 9.4T Static Magnetic Field

    PubMed Central

    Hahn, David; Boers, Frank; Shah, N. Jon

    2013-01-01

    Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4T were not different from those recorded at 0T. The amplitudes of ERPs were higher at 9.4T when compared to recordings at 0T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses. PMID:23650538

  3. Recording visual evoked potentials and auditory evoked P300 at 9.4T static magnetic field.

    PubMed

    Arrubla, Jorge; Neuner, Irene; Hahn, David; Boers, Frank; Shah, N Jon

    2013-01-01

    Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4 T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4 T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4 T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4 T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4 T were not different from those recorded at 0 T. The amplitudes of ERPs were higher at 9.4 T when compared to recordings at 0 T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses.

  4. Instrumentalization of movements evoked by stimulation of the motor cortex by food reinforcement in dogs.

    PubMed

    Frolov, A G; Pavlova, O G

    2003-03-01

    The possibility that hindlimb movements (elevations) evoked by stimulation of the corresponding contralateral area of the motor cortex could be instrumentalized by reinforcement with food was demonstrated, contradicting some previously published data. Operant movements (interstimulus voluntary high elevations of the hindlimb) were acquired as a result of consistent combinations: cortical stimulation - movement - food. Acquisition required more than 50-200 combinations. Delivery of food was accompanied by a click at exactly the moment at which the hindlimb reached the required height. The click became the food-related conditioned signal and served as a secondary operant reinforcement, which facilitated acquisition of the operant movement. These results support the view that the motor cortex can have an immediate role in forming "operant" temporary connections (motivation-movement) and that simple operant movements can be initiated via this arc.

  5. Promontory electrical stimulation to elicit vestibular evoked myogenic potentials (VEMPs).

    PubMed

    Park, Jonas J-H; Shen, Anmin; Westhofen, Martin

    2015-03-01

    Vestibular evoked myogenic potentials (VEMPs) provoked electrically at the promontory provide a feasible method to record vestibular responses in awake patients. Electrically evoked VEMP testing has been performed by galvanic stimulation at the mastoid so far. The present study examined an electrical stimulation mode close to the otolith organs at the promontory. Fourteen cochlear implant candidates who were planned for clinical routine promontory stimulation testing (PST) to assess auditory nerve function underwent promontory VEMP testing. After testing the cochlear nerve function during PST promontory cervical VEMPs (p-c-VEMPs) and promontory ocular VEMPs (p-o-VEMPs) were recorded during subsequent transtympanic electrical stimulation at the promontory. Promontory VEMP testing was well tolerated by the patients. Mean latencies for p-c-VEMPs were 10.30 ± 2.23 ms (p1) and 17.86 ± 3.83 ms (n1). Mean latencies for p-o-VEMPs were 7.64 ± 1.24 ms (n1) and 11.2 ± 1.81 ms (p1). The stimulation threshold level was measured at 0.15 ± 0.07 mA for p-c-VEMPs and at 0.19 ± 0.11 mA for p-o-VEMPs. The discomfort level was found to be at 0.78 ± 0.29 mA for p-c-VEMPs and at 0.69 ± 0.25 mA for p-oVEMPs. Mean p1-n1 amplitude in p-c-VEMPs was 124.78 ± 56.55 µV and p-o-VEMPs showed a mean n1-p1 amplitude of 30.94 ± 18.98 µV.

  6. A new role for evoked potentials in MS? Repurposing evoked potentials as biomarkers for clinical trials in MS.

    PubMed

    Hardmeier, Martin; Leocani, Letizia; Fuhr, Peter

    2017-09-01

    Evoked potentials (EP) characterize signal conduction in selected tracts of the central nervous system in a quantifiable way. Since alteration of signal conduction is the main mechanism of symptoms and signs in multiple sclerosis (MS), multimodal EP may serve as a representative measure of the functional impairment in MS. Moreover, EP have been shown to be predictive for disease course, and thus might help to select patient groups at high risk of progression for clinical trials. EP can detect deterioration, as well as improvement of impulse propagation, independently from the mechanism causing the change. Therefore, they are candidates for biomarkers with application in clinical phase-II trials. Applicability of EP in multicenter trials has been limited by different standards of registration and assessment.

  7. Applications of pain-related evoked potentials and short-latency somatosensory evoked potentials in acupuncture research: a narrative review.

    PubMed

    Lin, Chi; Ma, Liangxiao; Zhu, Shipeng; Hu, Nijuan; Wang, Pei; Zhang, Peng; Qi, Dandan; Hao, Jie; Li, Jing; Xin, Siyuan; Zhu, Jiang

    2015-10-01

    To review and discuss the Chinese and English literature on the use of pain-related evoked potentials (PREP) and short-latency somatosensory EP (SLSEP) in acupuncture research. China National Knowledge Infrastructure Database and MEDLINE were searched for the following key words: acupuncture and PREP or SLSEP. Thirty-seven articles were included in the review. Researchers usually use PREPs to study the analgesic effect of acupuncture, observe influential factors, or for mechanistic exploration. In the SLSEP studies, researchers focused on response characteristics of acupuncture, acupoint specificity, and influential factors of the treatment. There were some problems with the study design and conclusions. Researchers could use PREP and SLSEP to objectively validate the effects of acupuncture and explore its mechanisms using nerve electrophysiology. Further studies can benefit from observing more acupoints' effects using PREPs or SLSEPs and investigating the placebo effect of acupuncture.

  8. Mapping human brain networks with cortico-cortical evoked potentials.

    PubMed

    Keller, Corey J; Honey, Christopher J; Mégevand, Pierre; Entz, Laszlo; Ulbert, Istvan; Mehta, Ashesh D

    2014-10-05

    The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex.

  9. Mapping human brain networks with cortico-cortical evoked potentials

    PubMed Central

    Keller, Corey J.; Honey, Christopher J.; Mégevand, Pierre; Entz, Laszlo; Ulbert, Istvan; Mehta, Ashesh D.

    2014-01-01

    The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex. PMID:25180306

  10. Sensory-evoked and spontaneous gamma and spindle bursts in neonatal rat motor cortex.

    PubMed

    An, Shuming; Kilb, Werner; Luhmann, Heiko J

    2014-08-13

    Self-generated neuronal activity originating from subcortical regions drives early spontaneous motor activity, which is a hallmark of the developing sensorimotor system. However, the neural activity patterns and role of primary motor cortex (M1) in these early movements are still unknown. Combining voltage-sensitive dye imaging (VSDI) with simultaneous extracellular multielectrode recordings in postnatal day 3 (P3)-P5 rat primary somatosensory cortex (S1) and M1 in vivo, we observed that tactile forepaw stimulation induced spindle bursts in S1 and gamma and spindle bursts in M1. Approximately 40% of the spontaneous gamma and spindle bursts in M1 were driven by early motor activity, whereas 23.7% of the M1 bursts triggered forepaw movements. Approximately 35% of the M1 bursts were uncorrelated to movements and these bursts had significantly fewer spikes and shorter burst duration. Focal electrical stimulation of layer V neurons in M1 mimicking physiologically relevant 40 Hz gamma or 10 Hz spindle burst activity reliably elicited forepaw movements. We conclude that M1 is already involved in somatosensory information processing during early development. M1 is mainly activated by tactile stimuli triggered by preceding spontaneous movements, which reach M1 via S1. Only a fraction of M1 activity transients trigger motor responses directly. We suggest that both spontaneously occurring and sensory-evoked gamma and spindle bursts in M1 contribute to the maturation of corticospinal and sensorimotor networks required for the refinement of sensorimotor coordination.

  11. Vestibular evoked myogenic potentials (VEMPs) in central neurological disorders.

    PubMed

    Venhovens, J; Meulstee, J; Verhagen, W I M

    2016-01-01

    Several types of acoustic stimulation (i.e. tone bursts or clicks), bone-conducted vibration, forehead taps, and galvanic stimulation elicit myogenic potentials. These can be recorded in cervical and ocular muscles, the so called vestibular evoked myogenic potentials (VEMPs). The cervical VEMP (cVEMP) resembles the vestibulo-collic reflex and the responses can be recorded from the ipsilateral sternocleidomastoid muscle. The ocular VEMP resembles the vestibulo-ocular reflex and can be recorded from extra-ocular muscles by a surface electrode beneath the contralateral infraorbital margin. Initially, the literature concerning VEMPs was limited to peripheral vestibular disorders, however, the field of VEMP testing is rapidly expanding, with an increasing focus on central neurological disorders. The current literature concerning VEMP abnormalities in central neurological disorders is critically reviewed, especially regarding the methodological aspects in relation to quality as well as the clinical interpretation of the VEMP results. Suggestions for further research are proposed as well as some clinically useful indications. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  12. [Clinical study of time-shift evoked potentials].

    PubMed

    Chiba, H

    2000-05-01

    Quick change of the interaural time difference (ITD) generates moving sound stimuli. Specific biphasic event-related potentials called "time-shift evoked potentials (TSEPs)" can be recorded when this moving sound is given. The results of TSEPs in various types of hearing loss were analyzed in comparison with auditory brainstem response (ABR) and slow vertical response (SVR) in order to evaluate clinial applicability of TSEPs. Firstly, the detection threshold of TSEPs was established in groups of patients with low tone sensorineural hearing loss and with steep high tone sensorineural hearing loss. The usefulness of TSEPs was then evaluated in patients with retrocochlear hearing loss and with functional deafness. The patients with retrocochlear hearing loss were divided into 2 subgroups, one with auditory nerve disorder and the other with cortical disorder. It was found that TSEPs participate in the transference of auditory time-factors. They reflect the function of not only the auditory nerve and brainstem which form major components of ABR, but also the central nervous system superior to the inferior colliculus. TSEPs could be recorded in most patients with functional deafness and are more useful for its diagnosis than using the conventional directional hearing test. It is concluded that TSEPs is useful as a clinical test for detection of cortical disorder and functional deafness.

  13. Vestibular evoked myogenic potentials and habituation to seasickness.

    PubMed

    Tal, Dror; Hershkovitz, Dov; Kaminski-Graif, Gil; Wiener, Guy; Samuel, Orit; Shupak, Avi

    2013-12-01

    Seasickness may impose severe limitations on the performance of ships' crew. Cervical vestibular evoked myogenic potentials (cVEMP) assess the function of the saccule, the organ responsible for monitoring vertical linear acceleration, which has been found to be the most provocative motion stimulus in the evolution of motion sickness. We used the cVEMP test in a prospective evaluation of susceptibility and habituation to seasickness. Forty-six naval recruits underwent the cVEMP test before exposure to sea conditions. After 6 months' sailing experience, participants completed a questionnaire evaluating their initial and current seasickness severity. Based on their most recent experience, subjects were divided into three groups: non-vomiting non-habituating (NV-NH), vomiting (V), and non-vomiting habituating (NV-H). Statistically significant lower thresholds for cVEMP were found in subjects who habituated to sea conditions (NV-H), compared with those remaining severely susceptible (V) (77.0 dB HL vs. 84.9 dB HL; p<0.01). The ability to produce the cVEMP at lower thresholds represents a broader dynamic range, in which the reflex can respond to a wider array of stimuli amplitudes. The present study demonstrates the potential of the cVEMP test for predicting future habituation to seasickness. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  14. Laser Evoked Potentials in Early and Presymptomatic Huntington's Disease

    PubMed Central

    de Tommaso, Marina; Franco, Giovanni; Ricci, Katia; Montemurno, Anna; Sciruicchio, Vittorio

    2016-01-01

    Pain was rarely studied in Huntington's disease (HD). We presently aimed to extend our previous study on pain pathways functions by laser evoked potentials (LEPs) to a larger cohort of early unmedicated HD patients and a small group of presymptomatic HD (PHD) subjects. Forty-two early HD patients, 10 PHD patients, and 64 controls were submitted to LEPs by right-hand stimulation. Two series of 30 laser stimuli were delivered, and artifact-free responses were averaged. The N1, N2, and P2 latencies were significantly increased and the N2P2 amplitude significantly reduced in HD patients compared to controls. In the HD group, the LEPs abnormalities correlated with functional decline. PHD subjects showed a slight and insignificant increase in LEPs latencies, which was inversely correlated with the possible age of HD clinical onset. Data of the present study seem to suggest that the functional state of nociceptive pathways as assessed by LEPs may be a potential biomarker of disease onset and progression. The assessment of pain symptoms in premanifest and manifest HD may also open a new scenario in terms of subtle disturbances of pain processing, which may have a role in the global burden of the disease. PMID:27087746

  15. Visual Evoked Potentials in Children Prenatally Exposed to Methylmercury

    PubMed Central

    Yorifuji, Takashi; Murata, Katsuyuki; Bjerve, Kristian S.; Choi, Anna L; Weihe, Pal; Grandjean, Philippe

    2013-01-01

    Prenatal exposure to methylmercury can cause both neurobehavioral deficits and neurophysiological changes. However, evidence of neurotoxic effects within the visual nervous system is inconsistent, possibly due to incomplete statistical adjustment for beneficial nutritional factors. We evaluated the effect of prenatal methylmercury exposure on visual evoked potential (VEP) latencies in Faroese children with elevated prenatal methylmercury exposure. A cohort of 182 singleton term births was assembled in the Faroe Islands during 1994–1995. At age 7 years, VEP tracings were obtained from 139 cohort subjects after exclusion of subjects with abnormal vision conditions. We used multiple regression analysis to evaluate the association of mercury concentrations in cord blood and maternal hair at parturition with VEP latencies after adjustment for potential confounders that included the cord-serum phospholipid concentration of n-3 polyunsaturated fatty acids (PUFAs) and the duration of breastfeeding. Unadjusted correlations between mercury exposure and VEP latencies were equivocal. Multiple regression models showed that increased mercury concentrations, especially in maternal hair, were associated with delayed latencies for VEP peak N145. After covariate adjustment, a delay of 2.22 ms (p=0.02) was seen for each doubling of the mercury concentration in maternal hair. In agreement with neuropsychological findings, the present study suggests that prenatal methylmercury exposure may have an adverse effect on VEP findings despite the absence of clinical toxicity to the visual system. However, this association was apparent only after adjustment for n-3 PUFA status. PMID:23548974

  16. Vestibular evoked myogenic potentials in patients with ankylosing spondylitis.

    PubMed

    Özgür, Abdulkadir; Serdaroğlu Beyazal, Münevver; Terzi, Suat; Coşkun, Zerrin Özergin; Dursun, Engin

    2016-10-01

    Ankylosing spondylitis (AS) is a chronic systemic inflammatory disease with unknown etiology. Although sacroiliac joint involvement is the classic sign along with the formed immune mediators, it may result in immune-mediated inner ear disease and may cause damage to the audiovestibular system. Vestibular evoked myogenic potentials (VEMP) is a clinical reflex test used in the diagnosis of vestibular diseases and is performed by recording and evaluating the muscle potentials resulting from the stimulation of the vestibular system with different stimuli. The aim of this study is to evaluate the cervical VEMP test results in AS patients without vestibular symptoms. Thirty-three patients with AS and a control group of 30 healthy volunteers with similar demographic characteristics were evaluated in the study. VEMP wave latency, P13-N23 wave amplitude, and VEMP asymmetry ratio (VAR) values were compared between the groups. The relationship between clinical and laboratory findings of the AS patients and VEMP data were also investigated. Compared with healthy people, this study shows the response rate of patients with ankylosing spondylitis was reduced in the VEMP test, and P13-N23 wave amplitude showed a decrease in AS patients who had VEMP response (p < 0.001). There was no correlation between the clinical and laboratory findings and VEMP findings in patients with ankylosing spondylitis. The data obtained from this study suggest that AS may lead to decreased sensitivity of the vestibular system.

  17. Vestibular evoked myogenic potential findings in multiple sclerosis.

    PubMed

    Escorihuela García, Vicente; Llópez Carratalá, Ignacio; Orts Alborch, Miguel; Marco Algarra, Jaime

    2013-01-01

    Multiple sclerosis is an inflammatory disease involving the occurrence of demyelinating, chronic neurodegenerative lesions in the central nervous system. We studied vestibular evoked myogenic potentials (VEMPs) in this pathology, to allow us to evaluate the saccule, inferior vestibular nerve and vestibular-spinal pathway non-invasively. There were 23 patients diagnosed with multiple sclerosis who underwent VEMP recordings, comparing our results with a control group consisting of 35 healthy subjects. We registered p13 and n23 wave latencies, interaural amplitude difference and asymmetry ratio between both ears. Subjects also underwent an otoscopy and audiometric examination. The prolongation of p13 and n23 wave latencies was the most notable characteristic, with a mean p13 wave latency of 19.53 milliseconds and a mean latency of 30.06 milliseconds for n23. In contrast, the asymmetry index showed no significant differences with our control group. In case of multiple sclerosis, the prolongation of the p13 and n23 VEMP wave latencies is a feature that has been attributed to slowing of conduction by demyelination of the vestibular-spinal pathway. In this regard, alteration of the response or lack thereof in these potentials has a locator value of injury to the lower brainstem. Copyright © 2013 Elsevier España, S.L. All rights reserved.

  18. [Evoked potentials and regional cerebral blood flow changes in conversion disorder: a case report and review].

    PubMed

    Gürses, Nadide; Temuçin, Cağri Mesut; Lay Ergün, Eser; Ertuğrul, Aygün; Ozer, Suzan; Demir, Başaran

    2008-01-01

    Conversion disorder is defined as the presence of functional impairment in motor, sensory or neurovegetative systems which cannot be explained by a general medical condition. Although the diagnostic systems emphasize the absence of an organic basis for the dysfunction in conversion disorder, there has been a growing interest in the specific functional brain correlates of conversion symptoms in recent years, particularly by examining neuroimaging and neurophysiological measures. In this case report, regional cerebral blood flow changes and evoked potentials of a patient with conversion symptoms are presented. Somatosensory evoked potentials (SEP) of this patient with conversion disorder who had signs of movement disorder revealed that the latency to N20, P 25 waves were in normal limits while the amplitudes of the P25 and N33 components were extremely high (giant SEP). Regional cerebral blood flow assessment revealed hypoperfusion in the left parietal and temporal lobes of the brain. Three months after the first assessment, the control scans showed that the left parietal hypoperfusion disappeared while the left temporal hypoperfusion was still present. The following SEP evaluations which were repeated twice in three months intervals after the initial recordings, showed the persistence of the abnormalities in somatosensorial measures. The neurophysiological and neuroimaging findings in conversion disorder were reviewed and the results of the evaluations of this case were discussed in this article.

  19. Cold-evoked potentials - Ready for clinical use?

    PubMed

    Hüllemann, P; Nerdal, A; Binder, A; Helfert, S; Reimer, M; Baron, R

    2016-11-01

    Cold-evoked potentials (CEPs) are known to assess the integrity of A-delta fibres and the spinothalamic tract. Nevertheless, the clinical value was not investigated previously. The aim of this study was to measure CEPs in 16 healthy subjects from the face, hand and foot sole and to investigate whether CEPs reliably detect A-delta fibre abnormalities. Swift cold stimuli were applied to the skin with a commercially available thermode, which cooled down from 30 to 25 °C in approximately 0.5 s. CEP latencies (N1, N2 and P2) and amplitudes (N1, N2/P2) were recorded with EEG. Reversible A-fibre function loss was induced by applying a selective A-fibre block at the superficial radial nerve. In all 16 subjects CEPs could be recorded from all locations; N2, P2 mean latencies were 276.4 ± 38.9 and 389.8 ± 52.5 (face), 318.6 ± 31.6 ms and 477.7 ± 43.6 (hand), and 627.6 ± 84.4 and 774.2 ± 94.0 (foot sole). N2/P2 amplitudes were 10.7 ± 4.1, 11.3 ± 4.1 and 7.5 ± 4.1 μV. During A-fibre block no CEPs were detectable in the grand average, which restored 10 min after block removal. CEPs were reliably recorded in healthy subjects at the hand, face and foot. Experimentally induced reversible A-delta fibre function loss was detected by CEPs. Functional recovery was assessed as well. This study is basis for further CEP evaluation studies and might be the first step for implementing CEPs in clinical routine for the early diagnosis of small-fibre disease. WHAT DOES THIS STUDY ADD?: Cold-evoked potentials are capable of reliably measuring A-delta fibre integrity, loss of function and functional recovery in healthy subjects, which is an essential prerequisite for diagnostic use in patients with small-fibre disease. © 2016 European Pain Federation - EFIC®.

  20. Cortical auditory evoked potential (P1): a potential objective indicator for auditory rehabilitation outcome.

    PubMed

    Thabet, Mirahan T; Said, Nithreen M

    2012-12-01

    Cortical auditory evoked potentials are a non-invasive tool that can provide objective information on maturation of the auditory pathways. This work was designed to study the role of cortical auditory evoked potential (P1) in assessment of the benefits of amplification and aural rehabilitation in hearing impaired children. The study consisted of 31 children classified into 2 groups. Study group included 18 hearing impaired children ranging in age 4-14 years old and classified into two subgroups according to adequacy of aural rehabilitation. A control group consisted of 13 normal hearing children ranging in age from 5 to 13 years. All children were subjected to history taking, basic audiological evaluation, intelligence quotient and language assessment. Cortical auditory evoked potential (P1) was measured using synthesized speech syllable /da/ as a recording stimulus that was presented binaurally via a loudspeaker. P1 was recorded in all children with significantly prolonged latencies in hearing impaired children with inadequate rehabilitation. P1 latency was correlated to hearing loss duration in hearing impaired children with inadequate aural rehabilitation. Auditory experience was correlated with P1 latency in hearing impaired children with adequate aural rehabilitation. Cortical auditory evoked potential (P1) might provide a clinical tool to monitor aural rehabilitation outcome and to guide intervention choices. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  1. Repetitive magnetic stimulation affects the microenvironment of nerve regeneration and evoked potentials after spinal cord injury.

    PubMed

    Jiang, Jin-Lan; Guo, Xu-Dong; Zhang, Shu-Quan; Wang, Xin-Gang; Wu, Shi-Feng

    2016-05-01

    Repetitive magnetic stimulation has been shown to alter local blood flow of the brain, excite the corticospinal tract and muscle, and induce motor function recovery. We established a rat model of acute spinal cord injury using the modified Allen's method. After 4 hours of injury, rat models received repetitive magnetic stimulation, with a stimulus intensity of 35% maximum output intensity, 5-Hz frequency, 5 seconds for each sequence, and an interval of 2 minutes. This was repeated for a total of 10 sequences, once a day, 5 days in a week, for 2 consecutive weeks. After repetitive magnetic stimulation, the number of apoptotic cells decreased, matrix metalloproteinase 9/2 gene and protein expression decreased, nestin expression increased, somatosensory and motor-evoked potentials recovered, and motor function recovered in the injured spinal cord. These findings confirm that repetitive magnetic stimulation of the spinal cord improved the microenvironment of neural regeneration, reduced neuronal apoptosis, and induced neuroprotective and repair effects on the injured spinal cord.

  2. Theta Burst Stimulation of the Cerebellum Modifies the TMS-Evoked N100 Potential, a Marker of GABA Inhibition

    PubMed Central

    2015-01-01

    Theta burst stimulation (TBS) of the cerebellum, a potential therapy for neurological disease, can modulate corticospinal excitability via the dentato-thalamo-cortical pathway, but it is uncertain whether its effects are mediated via inhibitory or facilitatory networks. The aim of this study was to investigate the effects of 30Hz cerebellar TBS on the N100 waveform of the TMS-evoked potential (TEP), a marker of intracortical GABAB-mediated inhibition. 16 healthy participants (aged 18–30 years; 13 right handed and 3 left handed) received 30Hz intermittent TBS (iTBS), continuous TBS (cTBS) or sham stimulation over the right cerebellum, in three separate sessions. The first 8 participants received TBS at a stimulus intensity of 80% of active motor threshold (AMT), while the remainder received 90% of AMT. Motor evoked potentials (MEP) and TEP were recorded before and after each treatment, by stimulating the first dorsal interosseus area of the left motor cortex. Analysis of the 13 right handed participants showed that iTBS at 90% of AMT increased the N100 amplitude compared to sham and cTBS, without significantly altering MEP amplitude. cTBS at 80% of active motor threshold decreased the N100 amplitude and cTBS overall reduced resting MEP amplitude. The study demonstrates effects of 30Hz cerebellar TBS on inhibitory cortical networks that may be useful for treatment of neurological conditions associated with dysfunctional intracortical inhibition. PMID:26529225

  3. Evoked potential versus behavior to detect minor insult to the spinal cord in a rat model.

    PubMed

    Agrawal, Gracee; Thakor, Nitish V; All, Angelo H

    2009-08-01

    Reliable outcome measurement is needed for spinal cord injury research to critically evaluate the severity of injury and recovery thereafter. However, such measurements can sometimes be affected by minor, injury to the spinal cord during surgical procedures, including laminectomy. The open-field Basso, Beattie and Bresnahan (BBB) behavior motor scores are subjective and prone to human error. We investigated somatosensory evoked potential (SEP) as an electrophysiological measure to assess the integrity of the spinal cord after injury. In our experiment, control rats with a minor unintentional spinal cord insult during laminectomy showed a decrease in SEP amplitude by 16% to 18%, which recovered in around 7 days. However, there was no change in the BBB scores for the same animals over the same period. This highlights the sensitivity of SEP to minor insult as compared to BBB. These differences may be beneficial in accurate evaluation of the severity and progression of spinal cord injury, and subsequent recovery.

  4. ISCEV standard for clinical visual evoked potentials: (2016 update).

    PubMed

    Odom, J Vernon; Bach, Michael; Brigell, Mitchell; Holder, Graham E; McCulloch, Daphne L; Mizota, Atsushi; Tormene, Alma Patrizia

    2016-08-01

    Visual evoked potentials (VEPs) can provide important diagnostic information regarding the functional integrity of the visual system. This document updates the ISCEV standard for clinical VEP testing and supersedes the 2009 standard. The main changes in this revision are the acknowledgment that pattern stimuli can be produced using a variety of technologies with an emphasis on the need for manufacturers to ensure that there is no luminance change during pattern reversal or pattern onset/offset. The document is also edited to bring the VEP standard into closer harmony with other ISCEV standards. The ISCEV standard VEP is based on a subset of stimulus and recording conditions that provide core clinical information and can be performed by most clinical electrophysiology laboratories throughout the world. These are: (1) Pattern-reversal VEPs elicited by checkerboard stimuli with large 1 degree (°) and small 0.25° checks. (2) Pattern onset/offset VEPs elicited by checkerboard stimuli with large 1° and small 0.25° checks. (3) Flash VEPs elicited by a flash (brief luminance increment) which subtends a visual field of at least 20°. The ISCEV standard VEP protocols are defined for a single recording channel with a midline occipital active electrode. These protocols are intended for assessment of the eye and/or optic nerves anterior to the optic chiasm. Extended, multi-channel protocols are required to evaluate postchiasmal lesions.

  5. Auditory Evoked Potential Variability in Healthy and Schizophrenia Subjects

    PubMed Central

    Jansen, Ben H.; Hu, Lingli; Boutros, Nash N.

    2010-01-01

    Objectives To investigate if the reduced P50, N100 and P200 auditory evoked potential (EP) components and gating deficits seen in schizophrenia can be explained in terms of response incompleteness. Methods Twenty-five healthy and schizophrenia participants were studied using pairs of 1000 Hz tones (S1 and S2, 0.5 s apart) separated by 8.0 s. A correlation-based clustering method identified the responses containing P50, N100, and/or P200 related-activity. Results Schizophrenia participants produced fewer S1 and S2 responses containing all three EP components than healthy participants. Healthy participants, but not the patient population, produced fewer and smaller S2 than S1 responses containing all three EP components. However, the S2 responses following complete S1 responses were smaller than the complete S1 responses in both populations. Conclusions The gating deficits observed in schizophrenia are due to two mechanisms. First, the S1 response consistency is less in schizophrenia than in health. Second, the S2 responses are attenuated less in schizophrenia. Significance This research contributes to the understanding of response variability and sensory gating in health and schizophrenia. It also extends previous reports that fewer and smaller P300 components are produced in schizophrenia than in health to the mid-latency component range. PMID:20363180

  6. Cortical processing of human gut sensation: an evoked potential study.

    PubMed

    Hobday, David I; Hobson, Anthony R; Sarkar, Sanchoy; Furlong, Paul L; Thompson, David G; Aziz, Qasim

    2002-08-01

    The rectum has a unique physiological role as a sensory organ and differs in its afferent innervation from other gut organs that do not normally mediate conscious sensation. We compared the central processing of human esophageal, duodenal, and rectal sensation using cortical evoked potentials (CEP) in 10 healthy volunteers (age range 21-34 yr). Esophageal and duodenal CEP had similar morphology in all subjects, whereas rectal CEP had two different but reproducible morphologies. The rectal CEP latency to the first component P1 (69 ms) was shorter than both duodenal (123 ms; P = 0.008) and esophageal CEP latencies (106 ms; P = 0.004). The duodenal CEP amplitude of the P1-N1 component (5.0 microV) was smaller than that of the corresponding esophageal component (5.7 microV; P = 0.04) but similar to that of the corresponding rectal component (6.5 microV; P = 0.25). This suggests that rectal sensation is either mediated by faster-conducting afferent pathways or that there is a difference in the orientation or volume of cortical neurons representing the different gut organs. In conclusion, the physiological and anatomic differences between gut organs are reflected in differences in the characteristics of their afferent pathways and cortical processing.

  7. Ocular vestibular evoked myogenic potentials are abnormal in internuclear ophthalmoplegia.

    PubMed

    Rosengren, S M; Colebatch, J G

    2011-06-01

    The cervical vestibular evoked myogenic potential (cVEMP) is sensitive to lower brainstem lesions affecting the vestibulo-collic pathway. We wished to determine whether the ocular VEMP (oVEMP), a recently-described otolith-ocular reflex, is also abnormal in patients with brainstem lesions. We tested patients with internuclear ophthalmoplegia (INO), caused by a brainstem lesion in the medial longitudinal fasciculus (MLF), to investigate whether the oVEMP is abnormal in patients with a lesion of the otolith-ocular pathway. We describe a patient who developed a right INO during his first episode of demyelination, and report results from 12 additional patients, most of whom had multiple sclerosis. All subjects were stimulated with air-conducted tone bursts. cVEMPs and oVEMPs were measured using surface electrodes placed over the neck and beneath the eyes. Overall, oVEMPs showed significantly more abnormalities (69%) than cVEMPs (8%). Ocular VEMPs were absent with stimulation of 13/26 ears, significantly delayed in 5/26 cases and normal in only 8/26 cases. Ocular VEMPs are often abnormal in patients with multiple sclerosis who have an INO, while cVEMPs are usually normal. Ocular VEMPs provide a new, non-invasive method for examining central vestibular pathways in humans and are sensitive to lesions of the MLF. Copyright © 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  8. Hyperglycemia with occipital seizures: images and visual evoked potentials.

    PubMed

    Wang, Chung-Pang; Hsieh, Peiyuan F; Chen, Clayton Chi-Chang; Lin, Wan-Yu; Hu, Wei-Hsiung; Yang, Dar-Yu; Chang, Ming-Hong

    2005-07-01

    Hyperglycemia may rarely be seen with visual seizures. Observation of both visual evoked potentials (VEPs) and magnetic resonance imaging (MRI) in visual status epilepticus (SE) has not been reported. We describe acute and follow-up VEP and MRI findings of a patient with hyperglycemia-related visual SE of occipital origin. In a 59-year-old diabetic woman, complex visual hallucinations and illusions developed with < or =10 seizures per hour as an initial manifestation of nonketotic hyperglycemia. Neurologic examination revealed ictal nystagmus to the right and continuous right hemianopsia. Ictal electroencephalography (EEG) and Tc-99m hexamethylpropylene amine oxime (HMPAO) single-photon emission computed tomography (SPECT) revealed an epileptogenic focus in the left occipital lobe. MRI with fluid-attenuated inversion recovery showed focal subcortical hypointensity and gyral hyperintensity. Follow-up MRI showed only minimal gyral hyperintensity at 6 months. The P100 amplitude of VEP was significantly higher at the right occipital area during SE, but slightly higher on the left after the patient had been seizure free for 6 months. Occipital seizures and hemianopsia can be caused by hyperglycemia and may be accompanied by special MRI and VEP findings.

  9. Intraoperative monitoring of flash visual evoked potential under general anesthesia

    PubMed Central

    Hayashi, Hironobu

    2017-01-01

    In neurosurgical procedures that may cause visual impairment in the intraoperative period, the monitoring of flash visual evoked potential (VEP) is clinically used to evaluate visual function. Patients are unconscious during surgery under general anesthesia, making flash VEP monitoring useful as it can objectively evaluate visual function. The flash stimulus input to the retina is transmitted to the optic nerve, optic chiasm, optic tract, lateral geniculate body, optic radiation (geniculocalcarine tract), and visual cortical area, and the VEP waveform is recorded from the occipital region. Intraoperative flash VEP monitoring allows detection of dysfunction arising anywhere in the optic pathway, from the retina to the visual cortex. Particularly important steps to obtain reproducible intraoperative flash VEP waveforms under general anesthesia are total intravenous anesthesia with propofol, use of retinal flash stimulation devices using high-intensity light-emitting diodes, and a combination of electroretinography to confirm that the flash stimulus has reached the retina. Relatively major postoperative visual impairment can be detected by intraoperative decreases in the flash VEP amplitude. PMID:28367282

  10. Software for analysing multifocal visual evoked potential signal latency progression.

    PubMed

    de Santiago, L; Klistorner, A; Ortiz, M; Fernández-Rodríguez, A J; Rodríguez Ascariz, J M; Barea, R; Miguel-Jiménez, J M; Boquete, L

    2015-04-01

    This paper describes a new non-commercial software application (mfVEP(2)) developed to process multifocal visual-evoked-potential (mfVEP) signals in latency (monocular and interocular) progression studies. The software performs analysis by cross-correlating signals from the same patients. The criteria applied by the software include best channels, signal window, cross-correlation limits and signal-to-noise ratio (SNR). Software features include signal display comparing different tests and groups of sectors (quadrants, rings and hemispheres). The software's performance and capabilities are demonstrated on the results obtained from a patient with acute optic neuritis who underwent 9 follow-up mfVEP tests. Numerical values and graphics are presented and discussed for this case. The authors present a software application used to study progression in mfVEP signals. It is also useful in research projects designed to improve mfVEP techniques. This software makes it easier for users to manage the signals and allows them to choose various ways of selecting signals and representing results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Effect of stimulus check size on multifocal visual evoked potentials.

    PubMed

    Balachandran, Chandra; Klistorner, Alexander I; Graham, Stuart L

    2003-03-01

    In this study we examined the effects of varying stimulus check size on multifocal visual evoked potential (VEP). We also evaluated the currently used cortical scaling of stimulus segments. The ObjectiVision multifocal objective perimeter stimulates the eye with random check patterns at 56 cortically scaled segments within the visual field extending to a radius of 26 degrees. All cortically scaled segments have equal number of checks, which gradually increase in size from the center to the periphery, proportional to the size of the segment. Stimuli with 9, 16, 25, 36 and 49 checks/segment were tested on 10 eyes belonging to 10 normal subjects. The check size varied inversely with number of checks per segment. VEP was recorded using bipolar occipital cross electrodes (7 min/eye), the amplitude and latency of responses obtained were compared with the check size at different eccentricities. Our findings suggest that the existing setting with 16 checks/segment subtending 26' to 140' from center to periphery, is the most effective amongst all the check sizes. Decreasing the check size prolongs the latency in the central field only. Cortical scaling of segments generates responses of the same order of magnitude throughout the field, but could be improved slightly to enhance the signal from the outer two rings.

  12. Effect of pupil size on multifocal pattern visual evoked potentials.

    PubMed

    Martins, Alessandra; Balachandran, Chandra; Klistorner, Alexander I; Graham, Stuart L; Billson, Francis A

    2003-08-01

    The purpose of this study was to investigate the influence of pupil diameter on the amplitude and latency of multifocal visual evoked potentials (mfVEP). The multifocal objective perimeter (Accumap; Objectivision) was used to stimulate the visual field at 56 sites extending to 32 degrees using a pseudo-random pattern stimulus. The mfVEP were recorded using bipolar occipital electrodes, 7 min/eye. Ten normal subjects were recruited from the community and one eye was randomly selected for testing. The mfVEP were recorded at four different pupil diameters (2 mm, 4 mm, 6 mm, 8 mm), obtained by applying tropicamide (0.5%) or pilocarpine (2%) in different dilutions. Appropriate refractive correction was provided to overcome cycloplegia and achieve a visual acuity of 6/7.5 or better. Analysis revealed that at most pupil diameters the normalized full field amplitude did not show significant variation, except at the most miotic pupil diameter (2 mm), where the amplitude became reduced, based on 2-way anova and Tukey's T method. There was, however, significant correlation between latency and pupil area (correlation coefficient: upper field -0.63, lower field -0.76). The results suggest that even in the presence of mydriatics or miotics, the mfVEP test can be used to assess diseases that affect amplitude, provided near correction is used. The interpretation of latency, however, must be made with caution, as a borderline conduction defect with a dilated pupil may appear normal.

  13. Visual-evoked potentials in patients with brain circulatory problems.

    PubMed

    Pojda-Wilczek, Dorota

    2015-04-01

    The aim of this study was to find out if local brain circulatory problems may influence visual-evoked potentials (VEP). Thirty-eight patients were divided into the following groups: (I) those with hemianopsia or quadrantanopsia and hemiparesis after brain stroke; (II) those with hemianopsia or quadrantanopsia without paresis after brain stroke; and (III) those with amaurosis fugax. The control group consisted of 38 patients. The VEP pattern (PVEP) and flash VEP (FVEP) were examined monocularly using two electrodes placed at O1 and O2. Latency and amplitude of the N75, P100 and N2, P2 waves were measured. The Newman-Keuls test was used for statistical analysis. In PVEP, no differences between the groups were observed. In FVEP, the mean P2 latency was significantly longer in group I than in group III, and the P2 amplitude was significantly lower in all examined groups when compared with the control group. PVEP and FVEP revealed differences in P latency over 3 ms between brain hemispheres and differences in P amplitude over 30% in all examined groups. In the control group, there were no differences in latency between brain hemispheres and only a small difference in amplitude. Local brain circulatory problems that may lead to brain ischemia cause differences in VEP amplitude and latency between brain hemispheres. Changes in VEPs observed in patients with amaurosis fugax may be considered the result of recurrent brain ischemia.

  14. [Dipole tracing of visual evoked potentials in human brain].

    PubMed

    Shevelev, I A; Mikhaĭlova, E S; Kulikov, M A; Slavutskaia, A V

    2008-01-01

    3D tracing of equivalent current dipoles (ECDs) of averaged human visual evoked potentials (VEP) by their distribution across a 34-electrode array was obtained under short presentation of pattern-onset stimuli (sets of 45 horizontal, vertical bars or crosses). Using a 2-dipole spherical three-layer model, we dynamically (step of 1 ms) localized dipoles in four healthy subjects. Dipole locations were matched to anatomical brain regions visualized in structural MRI. Best-fitting source parameters were superimposed on MR images of each subject to identify the anatomical structures giving rise to the surface patterns. It was found that during 50-300 ms following the onset of the stimuli, the ECDs in all subjects were localized in the occipital cortex and demonstrated reliable systematic shift in localization. Two local (1-2 cm3) zones of the preferable dipole attendance were found at 5-6 cm behind zero line: the first one was localized near the midline of the brain, whereas the other zone was situated in the right hemisphere at a distance of 6-7 cm from the first zone. Their localization and strength of activation were reliably different for crosses and lines and changed during VEP generation. Zones of relatively rare dipole attendance were found also. The data are discussed in relation to localization of initial and endpoint of ECDs trajectories, as well as with sensitivity of the visual cortex to line crossing and branching.

  15. An Intelligent Decision System for Intraoperative Somatosensory Evoked Potential Monitoring.

    PubMed

    Fan, Bi; Li, Han-Xiong; Hu, Yong

    2016-02-01

    Somatosensory evoked potential (SEP) is a useful, noninvasive technique widely used for spinal cord monitoring during surgery. One of the main indicators of a spinal cord injury is the drop in amplitude of the SEP signal in comparison to the nominal baseline that is assumed to be constant during the surgery. However, in practice, the real-time baseline is not constant and may vary during the operation due to nonsurgical factors, such as blood pressure, anaesthesia, etc. Thus, a false warning is often generated if the nominal baseline is used for SEP monitoring. In current practice, human experts must be used to prevent this false warning. However, these well-trained human experts are expensive and may not be reliable and consistent due to various reasons like fatigue and emotion. In this paper, an intelligent decision system is proposed to improve SEP monitoring. First, the least squares support vector regression and multi-support vector regression models are trained to construct the dynamic baseline from historical data. Then a control chart is applied to detect abnormalities during surgery. The effectiveness of the intelligent decision system is evaluated by comparing its performance against the nominal baseline model by using the real experimental datasets derived from clinical conditions.

  16. Long-latency evoked potentials to irrelevant, deviant stimuli

    NASA Technical Reports Server (NTRS)

    Snyder, E.; Hillyard, S. A.

    1976-01-01

    Occasional shifts of loudness in a repetitive train of clicks elicited a late-positive wave (P3a) in nonattending subjects which peaked at a mean latency of 258 msec and had a frontocentral scalp distribution; P3a was typically preceded by an 'N2' component at 196 msec. The P3a wave was distinguishable from the longer-latency (378 msec) parietocentrally distributed 'P3b' wave that was evoked by the same stimulus in an actively attending subject, thus confirming the findings of Squires et al. (1975). Infrequently presented single sounds did not produce large or consistent N2-P3a components; the critical condition for the generation of an N2-P3a wave seemed to be that the infrequent sounds represent a deviation (intensity increment or decrement) from a repetitive background. Furthermore, increasing the repetition rate of the background clicks drastically reduced N1-P2 amplitude but had little effect on the amplitude of N2-P3a. This suggests that N2-P3a is not simply a delayed N1-P2 'vertex potential', but rather reflects the operation of a 'mismatch' detector, which registers deviations from an ongoing auditory background.

  17. Vestibular evoked myogenic potentials in patients with BPPV

    PubMed Central

    Korres, Stavros; Gkoritsa, Eleni; Giannakakou-Razelou, Dimitra; Yiotakis, Ioannis; Riga, Maria; Nikolpoulos, Thomas P.

    2011-01-01

    Summary Background The probable cause of Benign Paroxysmal Positional Vertigo (BPPV) is a degeneration of the oto lithic organs (utricle and saccule). The aim of the study is to find possible alterations in Vestibular Evoked Myogenic Potentials (VEMP) recordings in BPPV patients, because the saccule is part of the VEMP pathway. Material/Methods 27 BPPV patients (24 unilateral and 3 bilateral) aged 20 to 70 years and 30 healthy age matched controls. BPPV was diagnosed by the upbeating geotropic nystagmus found in the supine position with the head overextended towards one side. The subjects were investigated with pure tone audiometry, bi-thermal caloric test with electronystagmographic (ENG) recording, and VEMP recording. Results P1 latency and N1 latency did not present any statistical difference between control ears and affected ears of the BPPV population. The percentage of abnormal VEMP in the BPPV population was statistically higher than in the control ears (p<0.005). No significant relationship could be shown between the occurrence of Canal Paresis and abnormal VEMP. No relationship was found between the side (right or left ear) where BPPV appeared clinically and the side where abnormal VEMP was registered. Conclusions BPPV is a clinical entity associated with increased occurrence of abnormal VEMP recordings, possibly due to degeneration of the saccular macula, which is part of the neural VEMP pathway. PMID:21169909

  18. Reliability of vestibular evoked myogenic potentials in healthy subjects.

    PubMed

    Isaradisaikul, Suwicha; Strong, Darcy A; Moushey, Jamie M; Gabbard, Sandra A; Ackley, Steven R; Jenkins, Herman A

    2008-06-01

    To analyze test-retest reliability of vestibular evoked myogenic potential (VEMP) responses with and without the use of electromyography (EMG) monitoring in people with normal audiovestibular function. Twenty adult volunteers with no history of ear disease, normal otoscopic examination, normal pure-tone audiometry thresholds, and normal tympanograms. Prospective evaluation of VEMP responses with and without the use of EMG monitoring in 2 separate sessions 1 to 4 weeks apart. Threshold repeatability, p13 and n23 latency, p13-n23 interlatency, and interamplitude and interaural amplitude difference from the first and the second sessions were assessed via the intraclass correlation coefficient. Test-retest reliability of p13-n23 interamplitude was found to be excellent, and the reliability of threshold and latency was found to be fair to good (with the exception of poor reliability for p13 latency in the EMG monitoring condition). Overall, VEMP response parameters were found to have fair to good test-retest reliability. The intraclass correlation coefficient value for amplitude was found to be more reliable than latency, with the latency of n23 more reliable than the latency of p13. Clinicians should consider these findings when interpreting VEMP responses. Maintenance of symmetric head rotation with and without EMG monitoring produced reliably reproducible results, the VEMP amplitude being the best criteria.

  19. Flash visual evoked potentials in diurnal birds of prey.

    PubMed

    Dondi, Maurizio; Biaggi, Fabio; Di Ianni, Francesco; Dodi, Pier Luigi; Quintavalla, Fausto

    2016-01-01

    The objective of this pilot study was to evaluate the feasibility of Flash Visual Evoked Potentials (FVEPs) testing in birds of prey in a clinical setting and to describe the protocol and the baseline data for normal vision in this species. FVEP recordings were obtained from 6 normal adult birds of prey: n. 2 Harris's Hawks (Parabuteo unicinctus), n. 1 Lanner Falcon (Falco biarmicus), n. 2 Gyrfalcons (Falco rusticolus) and n. 1 Saker Falcon (Falco cherrug). Before carrying out VEP tests, all animals underwent neurologic and ophthalmic routine examination. Waveforms were analysed to identify reproducible peaks from random variation of baseline. At least three positive and negative peaks were highlighted in all tracks with elevated repeatability. Measurements consisted of the absolute and relative latencies of these peaks (P1, N1, P2, N2, P3, and N3) and their peak-to-peak amplitudes. Both the peak latency and wave morphology achieved from normal animals were similar to those obtained previously in other animal species. This test can be easily and safely performed in a clinical setting in birds of prey and could be useful for an objective assessment of visual function.

  20. Pattern Visual Evoked Potential Changes in Diabetic Patients without Retinopathy

    PubMed Central

    Sungur, Gulten; Yakin, Mehmet; Unlu, Nurten; Balta, Oyku Bezen; Ornek, Firdevs

    2017-01-01

    Purpose. To assess the different check sizes of pattern visual evoked potential (PVEP) in diabetic patients without retinopathy according to HbA1c levels and diabetes duration. Methods. Fifty-eight eligible patients with type 2 diabetes mellitus and 26 age- and sex-matched healthy controls were included in the study. Only the right eye of each patient was analyzed. All of the patients underwent a comprehensive ophthalmic examination, and the PVEPs were recorded. Results. There was a statistically significant difference in P100 latency in 1-degree check size and in N135 latency in 2-degree check size between controls and patient groups which have different HbA1c levels. There were statistically significant, positive, and weak correlations with diabetes duration and P100 latency in 7-minute and 15-minute check sizes and N135 latency in 15-minute check size. Conclusions. It was showed that there were prolongations in P100 latency only in 1-degree check size and in N135 only in 2-degree check size in diabetic patients without retinopathy. There was statistically significant correlation between diabetes duration and P100 and N135 latencies in different check sizes. PMID:28392940

  1. Pattern Visual Evoked Potentials Elicited by Organic Electroluminescence Screen

    PubMed Central

    Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Funada, Hideaki; Minoda, Haruka

    2014-01-01

    Purpose. To determine whether organic electroluminescence (OLED) screens can be used as visual stimulators to elicit pattern-reversal visual evoked potentials (p-VEPs). Method. Checkerboard patterns were generated on a conventional cathode-ray tube (S710, Compaq Computer Co., USA) screen and on an OLED (17 inches, 320 × 230 mm, PVM-1741, Sony, Tokyo, Japan) screen. The time course of the luminance changes of each monitor was measured with a photodiode. The p-VEPs elicited by these two screens were recorded from 15 eyes of 9 healthy volunteers (22.0 ± 0.8 years). Results. The OLED screen had a constant time delay from the onset of the trigger signal to the start of the luminescence change. The delay during the reversal phase from black to white for the pattern was 1.0 msec on the cathode-ray tube (CRT) screen and 0.5 msec on the OLED screen. No significant differences in the amplitudes of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by the CRT and the OLED screens. Conclusion. The OLED screen can be used as a visual stimulator to elicit p-VEPs; however the time delay and the specific properties in the luminance change must be taken into account. PMID:25197652

  2. Pattern visual evoked potentials elicited by organic electroluminescence screen.

    PubMed

    Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Funada, Hideaki; Sasaki, Kakeru; Minoda, Haruka; Iwata, Takeshi; Mizota, Atsushi

    2014-01-01

    To determine whether organic electroluminescence (OLED) screens can be used as visual stimulators to elicit pattern-reversal visual evoked potentials (p-VEPs). Checkerboard patterns were generated on a conventional cathode-ray tube (S710, Compaq Computer Co., USA) screen and on an OLED (17 inches, 320 × 230 mm, PVM-1741, Sony, Tokyo, Japan) screen. The time course of the luminance changes of each monitor was measured with a photodiode. The p-VEPs elicited by these two screens were recorded from 15 eyes of 9 healthy volunteers (22.0 ± 0.8 years). The OLED screen had a constant time delay from the onset of the trigger signal to the start of the luminescence change. The delay during the reversal phase from black to white for the pattern was 1.0 msec on the cathode-ray tube (CRT) screen and 0.5 msec on the OLED screen. No significant differences in the amplitudes of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by the CRT and the OLED screens. The OLED screen can be used as a visual stimulator to elicit p-VEPs; however the time delay and the specific properties in the luminance change must be taken into account.

  3. Flash visual evoked potentials in diurnal birds of prey

    PubMed Central

    Biaggi, Fabio; Di Ianni, Francesco; Dodi, Pier Luigi; Quintavalla, Fausto

    2016-01-01

    The objective of this pilot study was to evaluate the feasibility of Flash Visual Evoked Potentials (FVEPs) testing in birds of prey in a clinical setting and to describe the protocol and the baseline data for normal vision in this species. FVEP recordings were obtained from 6 normal adult birds of prey: n. 2 Harris’s Hawks (Parabuteo unicinctus), n. 1 Lanner Falcon (Falco biarmicus), n. 2 Gyrfalcons (Falco rusticolus) and n. 1 Saker Falcon (Falco cherrug). Before carrying out VEP tests, all animals underwent neurologic and ophthalmic routine examination. Waveforms were analysed to identify reproducible peaks from random variation of baseline. At least three positive and negative peaks were highlighted in all tracks with elevated repeatability. Measurements consisted of the absolute and relative latencies of these peaks (P1, N1, P2, N2, P3, and N3) and their peak-to-peak amplitudes. Both the peak latency and wave morphology achieved from normal animals were similar to those obtained previously in other animal species. This test can be easily and safely performed in a clinical setting in birds of prey and could be useful for an objective assessment of visual function. PMID:27547536

  4. Polar bear Ursus maritimus hearing measured with auditory evoked potentials.

    PubMed

    Nachtigall, Paul E; Supin, Alexander Y; Amundin, Mats; Röken, Bengt; Møller, Thorsten; Mooney, T Aran; Taylor, Kristen A; Yuen, Michelle

    2007-04-01

    While there has been recent concern about the effects of sound on marine mammals, including polar bears, there are no data available measuring the hearing of any bear. The in-air hearing of three polar bears was measured using evoked auditory potentials obtained while tone pips were played to three individually anaesthetized bears at the Kolmården Djurpark. Hearing was tested in half-octave steps from 1 to 22.5 kHz. Measurements were not obtainable at 1 kHz and best sensitivity was found in the range from 11.2-22.5 kHz. Considering the tone pips were short and background noise measurements were available, absolute measurements were estimated based on an assumed mammalian integration time of 300 ms. These data show sensitive hearing in the polar bear over a wide frequency range and should cause those concerned with the introduction of anthropogenic noise into the polar bear's environment to operate with caution.

  5. Visual evoked potentials in infants exposed to methadone in utero.

    PubMed

    McGlone, L; Mactier, H; Hamilton, R; Bradnam, M S; Boulton, R; Borland, W; Hepburn, M; McCulloch, D L

    2008-09-01

    We investigated the effects of maternal drug misuse on neonatal visual evoked potentials (VEPs). Flash VEPs were recorded within 4 days of birth from 21 term infants of mothers misusing drugs and prescribed substitute methadone and 20 controls. Waveforms were classified as typical, atypical, immature or non-detectable, and amplitude and latencies were measured. VEPs from drug-exposed infants were less likely to be of typical waveform and more likely to be immature or non-detectable (p<0.01) than those of control infants. They were also smaller in amplitude (median 10.8 vs 24.4 microV, p<0.001). VEPs of drug-exposed infants had matured after 1 week but remained of lower amplitude than VEPs of newborn controls (p<0.01) and were non-detectable in 15%. Flash VEPs differ between maternal drug-exposed and non-drug-exposed newborns. Future research should address the specific effects of maternal methadone and/or other illicit drug misuse on infant VEPs, and associations between neonatal VEPs and subsequent visual development.

  6. A Subspace Method for Dynamical Estimation of Evoked Potentials

    PubMed Central

    Georgiadis, Stefanos D.; Ranta-aho, Perttu O.; Tarvainen, Mika P.; Karjalainen, Pasi A.

    2007-01-01

    It is a challenge in evoked potential (EP) analysis to incorporate prior physiological knowledge for estimation. In this paper, we address the problem of single-channel trial-to-trial EP characteristics estimation. Prior information about phase-locked properties of the EPs is assesed by means of estimated signal subspace and eigenvalue decomposition. Then for those situations that dynamic fluctuations from stimulus-to-stimulus could be expected, prior information can be exploited by means of state-space modeling and recursive Bayesian mean square estimation methods (Kalman filtering and smoothing). We demonstrate that a few dominant eigenvectors of the data correlation matrix are able to model trend-like changes of some component of the EPs, and that Kalman smoother algorithm is to be preferred in terms of better tracking capabilities and mean square error reduction. We also demonstrate the effect of strong artifacts, particularly eye blinks, on the quality of the signal subspace and EP estimates by means of independent component analysis applied as a prepossessing step on the multichannel measurements. PMID:18288257

  7. Changes in vestibular evoked myogenic potentials after Meniere attacks.

    PubMed

    Kuo, Shih-Wei; Yang, Ting-Hua; Young, Yi-Ho

    2005-09-01

    The aim of this study was to apply videonystagmography (VNG) and vestibular evoked myogenic potential (VEMP) tests to patients with Meniere attacks, to explore the mechanics of where saccular disorders may affect the semicircular canals. From January 2001 to December 2003, 12 consecutive patients with unilateral definite Meniere's disease with vertiginous attacks underwent VNG for recording spontaneous nystagmus, as well as VEMP tests. At the very beginning of the Meniere attack, the spontaneous nystagmus beat toward the lesion side in 5 patients (42%) and toward the healthy side in 7 patients (58%). Twenty-four hours later, only 6 patients (50%) showed spontaneous nystagmus beating toward the healthy side. Nevertheless, spontaneous nystagmus subsided in all patients within 48 hours. The VEMP test was performed within 24 hours of a Meniere attack; the VEMPs were normal in 4 patients and abnormal in 8 patients (67%). After 48 hours, 4 patients with initially abnormal VEMPs had resolution and return to normal VEMPs, and the other 4 patients still had absent VEMPs. Most patients (67%) with Meniere attacks revealed abnormal VEMPs, indicating that the saccule participates in a Meniere attack. This is an important idea that stimulates consideration of the mechanism of Meniere attacks.

  8. Intraoperative monitoring of flash visual evoked potential under general anesthesia.

    PubMed

    Hayashi, Hironobu; Kawaguchi, Masahiko

    2017-04-01

    In neurosurgical procedures that may cause visual impairment in the intraoperative period, the monitoring of flash visual evoked potential (VEP) is clinically used to evaluate visual function. Patients are unconscious during surgery under general anesthesia, making flash VEP monitoring useful as it can objectively evaluate visual function. The flash stimulus input to the retina is transmitted to the optic nerve, optic chiasm, optic tract, lateral geniculate body, optic radiation (geniculocalcarine tract), and visual cortical area, and the VEP waveform is recorded from the occipital region. Intraoperative flash VEP monitoring allows detection of dysfunction arising anywhere in the optic pathway, from the retina to the visual cortex. Particularly important steps to obtain reproducible intraoperative flash VEP waveforms under general anesthesia are total intravenous anesthesia with propofol, use of retinal flash stimulation devices using high-intensity light-emitting diodes, and a combination of electroretinography to confirm that the flash stimulus has reached the retina. Relatively major postoperative visual impairment can be detected by intraoperative decreases in the flash VEP amplitude.

  9. Does speaker presentation affect auditory evoked potential thresholds in goldfish?

    PubMed

    Ladich, Friedrich; Wysocki, Lidia Eva

    2009-11-01

    The auditory evoked potential (AEP) recording technique has proved to be a very versatile and successful approach in studying auditory sensitivities in fishes. The AEP protocol introduced by Kenyon, Ladich and Yan in 1998 using an air speaker with the fish positioned at the water surface gave auditory thresholds in goldfish very close to behavioural values published before. This approach was subsequently modified by several laboratories, raising the question whether speaker choice (air vs. underwater) or the position of subjects affect auditory threshold determination. To answer these questions, the hearing specialist Carassius auratus was measured using an air speaker, an underwater speaker and alternately positioning the fish directly at or 5cm below the water surface. Mean hearing thresholds obtained using these 4 different setups varied by 5.6dB, 3.7dB and 4dB at 200Hz, 500Hz and 1000Hz, respectively. Accordingly, pronounced differences in AEP thresholds in goldfish measured in different laboratories reflect other factors than speaker used and depth of the test subjects, namely variations in threshold definition, background noise, population differences, or calibration errors.

  10. Diagnosis of deafness in a horse by brainstem auditory evoked potential

    PubMed Central

    Harland, Malte M.; Marshall, Arvle E.; Belknap, Ellen B.

    2006-01-01

    Abstract Deafness was confirmed in a blue-eyed, 3-year-old, overo paint horse by brainstem auditory evoked potential. Congenital inherited deafness associated with lack of facial pigmentation was suspected. Assessment of hearing should be considered, especially in paint horses, at the time of pre-purchase examination. Brainstem auditory evoked potential assessment is well tolerated and accurate. PMID:16579041

  11. [Intraoperative pain stimuli change somatosensory evoked potentials, but not auditory evoked potentials during isoflurane/nitrous oxide anesthesia].

    PubMed

    Rundshagen, I; Kochs, E; Bischoff, P; Schulte am Esch, J

    1997-10-01

    Evoked potentials are used for intraoperative monitoring to assess changes of cerebral function. This prospective randomised study assesses the influence of surgical stimulation on midlatency components of somatosensory (SEPs) and auditory evoked potentials (AEPs) in anaesthetised patients. After approval of the Ethics Committee and written informed consent 36 orthopaedic patients (34 +/- 15 y, 73 +/- 14 kg. 1.71 +/- 0.07 m, ASA I-II) were randomly included in the study. Anaesthesia was induced with 1.5 micrograms/kg fentanyl, 0.3 mg/kg etomidate and 0.1 mg/kg vecuronium. The lungs were intubated and patients normoventilated in steady state anaesthesia with isoflurane (end-tidal 0.6%) and 66% nitrous oxide. 18 patients (group 1) were assigned to the SEP group: median nerve stimulation, recording at Erb, C 6 and the contralateral somatosensory cortex (N20, P25, N35) vs Fz. AEPs were recorded in group 2 (n = 18): binaural stimulation, recording at Cz versus linked mastoid (V, Na, Pa, Nb). Recordings were performed during 30 min before the start of surgery (baseline: BL), at skin incision (SURG1) and at the preparation of the periost (SURG2). Heart rate, mean arterial blood pressure, oxygen saturation, endtidal pCO2 and isoflurane (PetISO) concentrations were registered simultaneously. Data were analysed by one-way analysis of variance. Post hoc comparison were made by Mann-Whitney U-Wilcoxon Rank Sum Test with p < 0.05 significant. During steady state isoflurane anaesthesia surgical stimulation (SURG2) resulted in significant increases of N20 P25 amplitudes compared with BL (BL: 1.4 +/- 0.7 microV; SURG2: 2.0 +/- 0.8 microV; p < 0.05). Latencies of SEPs and midlatency components of AEPs did not change over time. There were no differences in autonomic parameters between SEP and AEP groups. MAP increased from 76 +/- 6 mmHg at BL to 93 +/- 16 mmHg at SURG1 and 96 +/- 17 mmHg at SURG2 (n = 36; p < 0.05). HR increased from BL (60 +/- 8 beats/min) to SURG2 (76 +/- 12 beats

  12. Peripheral and segmental spinal abnormalities of median and ulnar somatosensory evoked potentials in Hirayama's disease

    PubMed Central

    Polo, A; Dossi, M; Fiaschi, A; Zanette, G; Rizzuto, N

    2003-01-01

    Objectives: To investigate the origin of juvenile muscle atrophy of the upper limbs (Hirayama's disease, a type of cervical myelopathy of unknown origin). Subjects: Eight male patients were studied; data from 10 normal men were used as control. Methods: Median and ulnar nerve somatosensory evoked potentials (SEP) were recorded. Brachial plexus potentials at Erb's point (EP), dorsal horn responses (N13), and subcortical (P14) and cortical potentials (N20) were evaluated. Tibial nerve SEP and motor evoked potentials (MEP) were also recorded from scalp and spinal sites to assess posterior column and pyramidal tract conduction, respectively. Results: The most important SEP findings were: a very substantial attenuation of both the EP potentials and the N13 spinal responses; normal amplitude of the scalp N20; and normal latency of the individual peaks (EP-N9-N13-P14-N20). Although both nerves were involved, abnormalities in response to median nerve stimulation were more significant than those in response to ulnar nerve stimulation. There was little correlation between the degree of alterations observed and the clinical state. Latencies of both spinal and cortical potentials were normal following tibial nerve stimulation. The mean latency of cervical MEP and the central conduction time from the thenar eminence were slightly but significantly longer in patients than in controls. Conclusions: The findings support the hypothesis that this disease, which is clinically defined as a focal spinal muscle atrophy of the upper limb, may also involve the sensory system; if traumatic injury caused by stretching plays a role in the pathogenesis, the damage cannot be confined to the anterior horn of the spinal cord. PMID:12700306

  13. n-Hexane-induced changes in nerve conduction velocities and somatosensory evoked potentials.

    PubMed

    Mutti, A; Ferri, F; Lommi, G; Lotta, S; Lucertini, S; Franchini, I

    1982-01-01

    Fifteen women from a shoe factory were examined clinically and their cerebral evoked responses to 256 electrical stimulations of the median nerve were averaged. Neurophysiological investigations included maximal motor (MCV) and distal sensory (dSCV) nerve conduction velocity measurement on ulnar, median, and peroneal nerves. A referent group was composed of 15 age-matched women without exposure to neurotoxic chemicals. MCVs and dSCVs of the exposed workers were significantly reduced vs referents, while P15 and N20 components of the somatosensory evoked potentials (SEP) showed an increased latency. A negative linear relationship was found between dSCV and P15 latency. However, two subjects with an abnormally low dSCV showed normal SEP latency, and two other subjects displayed abnormal SEP latency, while their dSCV was in the normal range. Therefore, SEP investigation may give additional information on nervous system function, even in subjects with peripheral neuropathy. The later SEP components were much flatter in the exposed than in the referent group, suggesting some neurotoxic effects of n-hexane on the central nervous system too.

  14. Single-trial detection for intraoperative somatosensory evoked potentials monitoring.

    PubMed

    Hu, L; Zhang, Z G; Liu, H T; Luk, K D K; Hu, Y

    2015-12-01

    Abnormalities of somatosensory evoked potentials (SEPs) provide effective evidence for impairment of the somatosensory system, so that SEPs have been widely used in both clinical diagnosis and intraoperative neurophysiological monitoring. However, due to their low signal-to-noise ratio (SNR), SEPs are generally measured using ensemble averaging across hundreds of trials, thus unavoidably producing a tardiness of SEPs to the potential damages caused by surgical maneuvers and a loss of dynamical information of cortical processing related to somatosensory inputs. Here, we aimed to enhance the SNR of single-trial SEPs using Kalman filtering and time-frequency multiple linear regression (TF-MLR) and measure their single-trial parameters, both in the time domain and in the time-frequency domain. We first showed that, Kalman filtering and TF-MLR can effectively capture the single-trial SEP responses and provide accurate estimates of single-trial SEP parameters in the time domain and time-frequency domain, respectively. Furthermore, we identified significant correlations between the stimulus intensity and a set of indicative single-trial SEP parameters, including the correlation coefficient (between each single-trial SEPs and their average), P37 amplitude, N45 amplitude, P37-N45 amplitude, and phase value (at the zero-crossing points between P37 and N45). Finally, based on each indicative single-trial SEP parameter, we investigated the minimum number of trials required on a single-trial basis to suggest the existence of SEP responses, thus providing important information for fast SEP extraction in intraoperative monitoring.

  15. A model of evoked potentials in spinal cord stimulation.

    PubMed

    Laird, James H; Parker, John L

    2013-01-01

    Electrical stimulation of the spinal cord is used for pain relief, and is in use for hundreds of thousands of cases of chronic neuropathic pain. In spinal cord stimulation (SCS), an array of electrodes is implanted in the epidural space of the cord, and electrical currents are used to stimulate nearby nerve fibers, believed to be in the dorsal columns of the cord. Despite the long history of SCS for pain, stretching over 30 years, its underlying mechanisms are poorly understood, and the therapy has evolved very little in this time. Recent work has resulted in the ability to record complex compound action potential waveforms during therapy. These waveforms reflect the neural activity evoked by the therapeutic stimulation, and reveal information about the underlying physiological processes. We aim to simulate these processes to the point of reproducing these recordings. We establish a hybrid model of SCS, composed of a three dimensional electrical model and a neural model. The 3D model describes the geometry of the spinal regions under consideration, and the electric fields that result from any flow of current within them. The neural model simulates the behaviour of spinal nerve fibers, which are the target tissues of the therapy. The combination of these two models is used to predict which fibers may be recruited by a given stimulus, as well as to predict the ensuing recorded waveforms. The model is shown to reproduce major features of spinal compound action potentials, such as threshold and propagation behaviour, which have been observed in experiments. The model's coverage of processes from stimulation to recording allows it to be compared side-by-side with actual experimental data, and will permit its refinement to a substantial level of accuracy.

  16. Neurotransmitter release evoked by nerve impulses without Ca2+ entry through Ca2+ channels in frog motor nerve endings.

    PubMed Central

    Silinsky, E M; Watanabe, M; Redman, R S; Qiu, R; Hirsh, J K; Hunt, J M; Solsona, C S; Alford, S; MacDonald, R C

    1995-01-01

    1. The requirement for extracellular Ca2+ in the process of evoked acetylcholine (ACh) release by nerve impulses was tested at endplates in frog skeletal muscle. Ca(2+)-containing lipid vesicles (Ca2+ liposomes) were used to elevate cytoplasmic Ca2+ concentrations under conditions in which Ca2+ entry from the extracellular fluid was prevented. 2. In an extracellular solution containing no added Ca2+ and 1 mM Mg2+ ('Ca(2+)-free' solution), Ca2+ liposomes promoted the synchronous release of ACh quanta, reflected electrophysiologically as endplate potentials (EPPs), in response to temporally isolated nerve impulses. 3. Motor nerve stimulation generated EPPs during superfusion with Ca2+ liposomes in Ca(2+)-free solutions containing the Ca2+ channel blocker Co2+ (1 mM), and the Ca2+ chelator EGTA (2 mM). As a physiological control for Ca2+ leakage from the liposomes to the extracellular fluid, the effect of Ca2+ liposomes on asynchronous evoked ACh release mediated by Ba2+ was examined. In contrast to the effects of 0.2-0.3 mM extracellular Ca2+, which generated EPPs but antagonized Ba(2+)-mediated asynchronous ACh release, Ca2+ liposomes generated EPPs but did not reduce asynchronous release mediated by Ba2+. The effects of Ca2+ liposomes were thus not due to leakage of Ca2+ from the liposome to the extracellular fluid. 4. Morphological studies using fluorescently labelled liposomes in conjunction with a confocal microscope demonstrate that lipid is transferred from the liposomes to nerve endings and liposomal contents are delivered to the nerve terminal cytoplasm. 5. The results suggest that when intracellular Ca2+ is elevated using liposomes as a vehicle, evoked ACh release can occur in the absence of Ca2+ entry via Ca2+ channels. Images Figure 5 Figure 6 PMID:7738845

  17. [Origin of olfactory and rhinosensory evoked cortical potentials in diseases of the central nervous system].

    PubMed

    Westhofen, M; Herberhold, C; Thayssen, G; Jend, H H

    1985-08-01

    This is the first report to be published on olfactory evoked potentials in patients with well-defined lesions of the central nervous system and the trigeminal nerve. Absence of olfactory evoked potentials is seen in post-central and parietotemporal lesions. The first peak of the so-called olfactory evoked twin potential is absent in lesions of the basal nuclei and sectioning of the trigeminal or ophthalmic nerve, whereas there is no second peak in subcortico-frontal and cortico-temporal lesions. Tumours of the corpus callosum and sectioning of the maxillary and mandibular nerves do not disturb the olfactory evoked potentials. The anatomically different localisation and the functional synergism of the olfactory and trigeminal systems in the perception of odours and the processing of olfactory evoked potentials are pointed out.

  18. Comparison of descending volleys evoked by transcranial and epidural motor cortex stimulation in a conscious patient with bulbar pain.

    PubMed

    Di Lazzaro, V; Oliviero, A; Pilato, F; Saturno, E; Dileone, M; Meglio, M; Cioni, B; Papacci, F; Tonali, P A; Rothwell, J C

    2004-04-01

    To compare the pattern of activation of motor cortex produced by transcranial magnetic stimulation and epidural electrical stimulation. The spinal volleys evoked by transcranial magnetic stimulation and epidural electrical stimulation over the cerebral motor cortex were recorded from an electrode inserted into the cervical epidural space of one conscious subject who also had a cortical epidural electrode over the motor area. The volleys were termed D- and I-waves according to their latency. Magnetic stimulation was performed with a figure-of-eight coil and the induced current flowed either in a postero-anterior (PA) or in latero-medial (LM) direction. At active motor threshold intensity LM magnetic stimulation evoked a D wave whereas PA stimulation evoked an I(1) wave with later I waves being recruited at increasing stimulus intensities. Electrical epidural stimulation evoked both a D wave and I waves. However, the D wave evoked by electrical epidural stimulation had a longer latency than the LM D wave, suggesting either a more proximal site of activation of the pyramidal axon or activation of slightly faster conducting set of corticospinal fibres by LM stimulation. The I3 wave evoked by electrical epidural stimulation also had a longer latency than the PA I3-wave Epidural stimulation of the motor cortex can produce repetitive excitation of corticospinal neurones. The order of recruitment of the volleys, and the latency of the D and I3 waves may be slightly different to that seen after transcranial magnetic stimulation. Our findings suggest that there may be subtle differences in the populations of neurones activated by the two forms of stimulation.

  19. Vestibular evoked myogenic potentials versus vestibular test battery in patients with Meniere's disease.

    PubMed

    Rauch, Steven D; Silveira, M Beatriz; Zhou, Guangwei; Kujawa, Sharon G; Wall, Conrad; Guinan, John J; Herrmann, Barbara S

    2004-11-01

    The present study was undertaken to assess the sensitivity of vestibular evoked myogenic potentials testing to side-of-disease in Meniere's disease patients and to test the hypothesis that information supplied by vestibular evoked myogenic potentials is complementary to that provided by a conventional vestibular test battery. Prospective cohort study. Large specialty hospital, department of otolaryngology. Twenty consenting adults (9 men and 11 women) with unilateral Meniere's disease by American Academy of Otolaryngology-Head and Neck Surgery diagnostic criteria. All subjects underwent bilateral vestibular evoked myogenic potentials testing using ipsilateral broadband click and short-toneburst stimuli at 250, 500, and 1,000 Hz. All subjects also underwent electronystagmography and sinusoidal vertical axis rotation testing. Accuracy of side-of-disease assignment by vestibular evoked myogenic potentials, caloric asymmetry, and multivariate analysis. Side-of-disease assignment was most accurate using caloric asymmetry with a 5% interaural difference criterion, achieving 85% correct assignment. The next best method was vestibular evoked myogenic potentials using 250-Hz toneburst stimuli, achieving 80% correct assignment. The least accurate method was caloric asymmetry using a traditional 30% interaural difference limen, achieving 55% correct assignment. Comparison of 5% interaural difference criterion and vestibular evoked myogenic potentials using 250-Hz toneburst stimuli showed discordant results, but in no case did both 5% interaural difference criterion and vestibular evoked myogenic potentials using 250-Hz toneburst stimuli make an incorrect assignment. Vestibular evoked myogenic potentials threshold was shown to be highly sensitive to side-of-disease in unilateral Meniere's disease. We observed instances of discordance in side-of-disease assignment by caloric asymmetry and vestibular evoked myogenic potential methods but no case in which both methods were

  20. [The effect of noradrenaline on the neuronal reactions of the motor cortex evoked by conditional stimulation].

    PubMed

    Storozhuk, V M; Stezhka, V V; Ivanova, S F

    1990-01-01

    In chronic experiments on cats the influence of iontophoretic application of adrenomimetic ephedrin and beta-adrenoblocker obsidan (propranolol) on motor cortex neuron reactions following conditional stimuli was investigated under instrumental placing reaction. It was shown for a majority of neurons that the background impulse activity and reactions following conditional stimulation were suppressed by the influence of ephedrin and on the contrary were increased by obsidan application. It is concluded that there exists a consistent tonic suppressing influence of the noradrenergic system on background and evoked cortical neurons impulse activity in the natural state. It is supposed that noradrenergic influence temporal increase may serve as an important link in mechanisms of external inhibition during stress situations, aversive effects, and distractive external excitations.

  1. Giant early components of somatosensory evoked potentials to tibial nerve stimulation in cortical myoclonus.

    PubMed

    Anzellotti, Francesca; Onofrj, Marco; Bonanni, Laura; Saracino, Antonio; Franciotti, Raffaella

    2016-01-01

    Enlarged cortical components of somatosensory evoked potentials (giant SEPs) recorded by electroencephalography (EEG) and abnormal somatosensory evoked magnetic fields (SEFs) recorded by magnetoencephalography (MEG) are observed in the majority of patients with cortical myoclonus (CM). Studies on simultaneous recordings of SEPs and SEFs showed that generator mechanism of giant SEPs involves both primary sensory and motor cortices. However the generator sources of giant SEPs have not been fully understood as only one report describes clearly giant SEPs following lower limb stimulation. In our study we performed a combined EEG-MEG recording on responses elicited by electric median and tibial nerve stimulation in a patient who developed consequently to methyl bromide intoxication CM with giant SEPs to median and tibial nerve stimuli. SEPs wave shapes were identified on the basis of polarity-latency components (e.g. P15-N20-P25) as defined by earlier studies and guidelines. At EEG recording, the SEP giant component did not appear in the latency range of the first cortical component for median nerve SEP (N20), but appeared instead in the range of the P37 tibial nerve SEP, which is currently identified as the first cortical component elicited by tibial nerve stimuli. Our MEG and EEG SEPs recordings also showed that components in the latency range of P37 were preceded by other cortical components. These findings suggest that lower limb P37 does not correspond to upper limb N20. MEG results confirmed that giant SEFs are the second component from both tibial (N43m-P43m) and median (N27m-P27m) nerve stimulation. MEG dipolar sources of these giant components were located in the primary sensory and motor area.

  2. Connections of the limbic network: a corticocortical evoked potentials study.

    PubMed

    Enatsu, Rei; Gonzalez-Martinez, Jorge; Bulacio, Juan; Kubota, Yuichi; Mosher, John; Burgess, Richard C; Najm, Imad; Nair, Dileep R

    2015-01-01

    Papez proposed a network for higher brain function, which is termed the limbic network. However, the in vivo human limbic network has not been established. We investigated the connectivity of the human limbic system using corticocortical evoked potential (CCEP). This retrospective analysis included 28 patients with medically intractable focal epilepsy who underwent stereoelectroencephalography (SEEG) and CCEP. Alternating 1 Hz electrical stimuli were delivered to parts of the limbic system [anterior and posterior hippocampus, temporal pole, parahippocampal gyrus (PHG), amygdala, anterior (ACG) and posterior cingulate gyrus (PCG), medial and lateral orbitofrontal cortex (OF)]. A total of 40-60 stimuli were averaged in each trial to obtain CCEP responses. CCEP distributions were evaluated by calculating the root mean square (RMS) of CCEP responses. Anterior hippocampal stimulation elicited prominent CCEP responses in medial and lateral temporal structures, PCG, medial OF and insula over the ipsilateral hemisphere. Posterior hippocampal stimulation induced CCEP responses in the ipsilateral medial and lateral temporal structures and PCG. The findings also revealed connections from temporal pole to the ipsilateral medial temporal structures, and connections from PHG to the ipsilateral hippocampus and PCG. The amygdala projected to broad areas including the ipsilateral medial and lateral temporal structures, medial and lateral frontal areas, the cingulate gyrus, insula and inferior parietal lobule. ACG and PCG showed connections to the ipsilateral medial fronto-parietal areas and connections to bilateral medial temporo-parieto-occipital and lateral parieto-occipital areas, respectively. Medial and lateral OF stimulation induced responses in the adjacent cortices. This study revealed that various regions within the limbic network are intimately connected in reverberating circuits and are linked to specific ipsilateral and contralateral regions, which may reflect

  3. Visual function with acupuncture tested by visual evoked potential.

    PubMed

    Sagara, Yoshiko; Fuse, Nobuo; Seimiya, Motohiko; Yokokura, Syunji; Watanabe, Kei; Nakazawa, Toru; Kurusu, Masayuki; Seki, Takashi; Tamai, Makoto

    2006-07-01

    Visual evoked potential (VEP) testing is used frequently and is an important ophthalmologic physiological test to examine visual functions objectively. The VEP is a complicated waveform consisting of negative waveform named N75 and N135, and positive waveform named P100. Delayed P100 latency and greatly attenuated amplitude on VEP are known characteristics for diagnosing optic nerve disease. Acupuncture has been used to treat wide clinical symptoms with minimal side effects. The confirmation of the efficacy of acupuncture generally relies on subjective symptoms. There is not much scientific evidence supporting the acupuncture treatments for eye diseases up to today. However, the VEP test can evaluate objectively and numerically the efficacy of the treatment by the acupuncture. We analyzed 19 healthy subjects (38 eyes). The P100 latencies in the group of less than 101.7 msec (total average) before acupuncture stimulations were not different than those after treatment (98.2 +/- 3.0 msec, 98.2 +/- 4.0 msec, respectively, p = 0.88, n = 17), but the latencies in those subjects with longer or equal to 101.7 msec were statistically different after acupuncture (104.6 +/- 2.8 msec, 101.9 +/- 3.7 msec, respectively, p = 0.006, n = 21). These results show that the acupuncture stimulation contributes to the P100 latencies of pattern reversal (PR)-VEP to some subjects who have delayed latencies, and this electrophysiological method is a valuable technique in monitoring the effectiveness of acupuncture therapy in the improvements of visual functions. The purpose of this study is to evaluate the physiological effects by acupuncture stimulations using PR-VEP in normal subjects.

  4. Peripheral sensitization reduces laser-evoked potential habituation.

    PubMed

    Hüllemann, P; Watfeh, R; Shao, Y-Q; Nerdal, A; Binder, A; Baron, R

    2015-12-01

    Laser-evoked potential (LEP) habituation was investigated under the influence of capsaicin-induced peripheral and central sensitization. Fifteen subjects received 100 repetitive painful laser stimuli at the right hand dorsum at primary (application area; condition I) and secondary areas (beyond application area; condition II) in two different sessions after applying capsaicin topically. Conditions I and II were compared to a control condition without capsaicin application. N1, N2, and P2 latencies and N1 and N2/P2 amplitudes were recorded by EEG. Quantitative sensory testing (QST) and the Liewald Diary reaction time experiment were used as control tests. QST documented heat hyperalgesia as a sign of peripheral sensitization in the primary area and pinprick hyperalgesia in the primary and secondary area as a sign of central sensitization, after applying capsaicin. The N2/P2 amplitude habituation was significantly reduced in the primary area compared to controls (the primary area represents peripheral sensitization). The LEPs of the secondary area (the secondary area represents central sensitization) showed no significant N2/P2 amplitude habituation compared to controls. The comparison between conditions I vs. II showed no significant difference regarding N2/P2 amplitude and laser pain rating. Capsaicin-induced central sensitization does not alter LEP habituation. The physiological habituation of LEP amplitudes is reduced due to peripheral mechanisms after applying capsaicin topically. These findings form a basis for future studies, which use the habituation paradigm to investigate pain conditions promoted by sensitization phenomena. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  5. Vestibular-evoked myogenic potentials in central vestibular disorders.

    PubMed

    Oh, Sun-Young; Kim, Hyo-Jeong; Kim, Ji-Soo

    2016-02-01

    Vestibular-evoked myogenic potentials (VEMPs) are short latency manifestations of vestibulo-ocular and vestibulocollic reflexes that originate from the utricle and saccule. Although cervical and ocular VEMPs have mostly been applied to peripheral vestibular disorders, the characteristics and the diagnostic values of VEMPs have been expanded to assess the function of the central otolithic pathways. In the central nervous system, the cervical VEMPs (cVEMPs) are mediated by the vestibular nuclei and uncrossed medial vestibulospinal tract descending in the lower brainstem and spinal cord. In contrast, the ocular VEMPs (oVEMPs) reflect the function of the vestibular nuclei and the crossed vestibulo-ocular reflex (VOR) pathways, mostly contained in the medial longitudinal fasciculus (MLF). Therefore, lesions involving the vestibular nuclei can present abnormalities of both cVEMPs and oVEMPs. The medullary lesions involving the descending MLF or the spinal accessory nucleus impair cVEMPs. In contrast, the lesions involving the MLF, the crossed ventral tegmental tract, oculomotor nuclei and the interstitial nucleus of Cajal can impair oVEMPs. Patients with unilateral cerebellar infarctions may show abnormal VEMPs especially when they have the ocular tilt reaction. Delayed responses of VEMPs are characteristic of multiple sclerosis (MS). Reduced VEMP responses can be observed in patients with vestibular migraine. VEMPs are useful in evaluating central as well as peripheral otolithic function that are not readily defined by conventional vestibular function tests, and can aid in detecting and localizing central lesions, especially silent brainstem lesions such as tiny infarctions or MS plaques.

  6. Effect of fixation tasks on multifocal visual evoked potentials.

    PubMed

    Martins, Alessandra; Klistorner, Alexander; Graham, Stuart; Billson, Frank

    2005-10-01

    This study investigated the effects of cognitive influence on the multifocal visual evoked potential (mVEP) at different levels of eccentricity. Three different foveal fixation conditions were utilized involving varying levels of task complexity. A more complex visual fixation task has been known to suppress peripheral signals in subjective testing. Twenty normal subjects had monocular mVEPs recorded using the AccuMap objective perimeter. This allowed simultaneous stimulation of 58 segments of the visual field to an eccentricity of 24 degrees. The mVEP was recorded using three different fixation conditions in random order. During task 1 the subject passively viewed the central fixation area. For task 2 alternating numbers were displayed within the fixation area; the subject on viewing the number '3' in the central fixation area indicated recognition by pressing a button. Throughout task 3, numbers were displayed as in task 2. The subject had the cognitive task of summating all the numbers. Analysis revealed that the increased attention and concentration demanded by tasks 2 and 3 in comparison with task 1 resulted in significantly enhanced central amplitudes of 9.41% (Mann-Whitney P = 0.0002) and 13.45% (P = 0.0002), respectively. These amplitudes became reduced in the periphery and approached those of task 1, resulting in no significant difference between the three tasks. Latencies demonstrated no significant difference between each task nor at any eccentricity (P > 0.05). As the complexity of each task increased the amount of alpha rhythm was significantly reduced. Our findings indicate that task 1 required a minimal demand of cognition and was associated with the greatest amount of alpha rhythm. It was also the most difficult to perform because of loss of interest. The other two tasks required a greater demand of higher order cognitive skills resulting in significantly enhanced amplitudes centrally and the attenuation of alpha rhythm. Therefore, amplitudes are

  7. Visual evoked potentials in patients with pineal gland cyst.

    PubMed

    Bosnjak, Jelena; Mikula, Ivan; Miskov, Snjezana; Budisic, Mislav; Ivkic, Goran; Demarin, Vida

    2012-09-01

    The functional effect of the pineal gland cyst is difficult to evaluate with visual field examination. The aim of this study is to investigate the usefulness of visual evoked potentials (VEP) in patients with pineal gland cyst due to the possible compression on the visual pathway. Black-and-white pattern-reversal checkerboard VEP were recorded in 75 patients (50 females and 25 males, mean age 26.3 ± 15.7 and 25.6 ± 17.6 years, respectively) with pineal gland cyst detected on magnetic resonance of the brain (subject group) and 75 age and sex-matched control subjects (control group). Amplitudes and P100 latencies were collected and later grouped as: (1) normal finding; (2) prechiasmal; (3) prechiasmal and postchiasmal; and (4) postchiasmal dysfunction. P100 latencies differed significantly between subject (110.26 ± 13.23 ms) and control group (101.01 ± 5.36 ms) (p < 0.01). Findings of the VEP differed significantly (p < 0.01) between subject and control group, mainly due to the postchiasmal dysfunction frequency in subject group. Findings of the VEP differed significantly according to the pineal gland cyst volume (p = 0.006) with more frequent postchiasmal dysfunctions among subjects with larger cysts. Postchiasmal changes were significantly more frequent in patients with described compression of the cyst on surrounding brain structures (p = 0.016). Postchiasmal dysfunction on VEP can be seen in patients with pineal gland cyst, mostly with larger cysts and with compression of the cyst on surrounding brain structures. VEP serve as a useful method to determine functional impairment of the visual pathway in patients with pineal gland cyst.

  8. Visual evoked potentials in subgroups of migraine with aura patients.

    PubMed

    Coppola, Gianluca; Bra