Masseter Vestibular evoked myogenic potentials: A new tool to assess the vestibulomasseteric reflex pathway

Purpose: This review article provides the readers with an in-depth insight in understanding and interpreting various research literatures on the masseter vestibular evoked myogenic potentials(mVEMP). The article also reviews the contemporary researches involving the clinical applications of the mVEMP. Conclusions: Masseter VEMP is an evolving yet clinically promising neuro-otology test tool that has recently gained more research interest and is considered an additional tool to diagnose various vestibular disorders. Masseter VEMP assesses the functional integrity of the acoustic-masseteric and vestibulo-masseteric reflex pathways. The mVEMP could be used as a complementary test to evaluate the same peripheral generator as the cervical VEMP but a different central pathway i.e., vestibulo-trigeminal pathway. Various research studies that have experimented on parameters such as the effect of different electrode montages(zygomatic vs mandibular configurations), stimulation rates, filter settings and stimuli used to evoke mVEMP have been discussed in this article that could assist in the optimization of a comprehensive clinical protocol. The latency and the amplitude of mVEMP waveforms serve as significant parameters in differentiating normals from those of the clinical populations. Along with the cVEMPs and oVEMPs, mVEMP might help diagnose brainstem lesions in REM Sleep behaviour disorders, Multiple Sclerosis and Parkinson's disease. However, further studies are required to probe in this area of research.

Median Nerve Somatosensory Evoked Potentials in Patients with Chiari Malformation

Abnormal SEP reflects dysfunction of the medial lemniscus and posterior cervical cord. These structures are likely to be affected in Chiari malformation. Therefore, SEP abnormalities may provide valuable information in patients with CM. However, the consistency of SEP abnormality or normality with the damage is a matter of research. Knowing whether median nerve somatosensory evoked potential (SEP) is useful in revealing subclinical damage in patients with Chiari malformation is important in the treatment and follow-up plan of the disease. The aim of this study was to investigate the relationship between median nerve SEP values and the severity of cerebellar ectopia in patients with Chiari type 1 malformation. Median nerve SEP values were obtained from 30 healthy individuals and 146 individuals with Chiari malformation. The cerebellar ectopia degree and McRae line length were measured. SEP values were not significantly different between groups. The McRae line was found to be significantly shorter in the control group than in the Chiari malformation group (p = 0.031). There was no correlation between the degree of cerebellar ectopia and the length of the McRae line (r = 0.002, p = 0.979). Neither cerebellar ectopy degree nor McRae line length had a relationship with SEP values (r = -0.153, p = 0.066;r = -0.056, p = 0.500, respectively). There was no difference in cerebellar ectopy degree or SEP values between the groups with cerebellar ectopy with and without a syrinx (p = 0.899;p = 0.080, respectively). Likewise, McRae line length was not found to be related to the presence of a syrinx (p = 0.139). Median nerve SEP examination was not beneficial for diagnosing asymptomatic-oligosymptomatic Chiari malformation as a subclinical injury, whether accompanied by syringomyelia or not.

Identification of injury type using somatosensory and motor evoked potentials in a rat spinal cord injury model

The spinal cord is at risk of injury during spinal surgery.If intraoperative spinal co rd injury is identified early,irreve rsible impairment or loss of neurological function can be prevented.Different types of spinal cord injury result in damage to diffe rent spinal cord regions,which may cause diffe rent somatosensory and motor evoked potential signal res ponses.In this study,we examined electrophysiological and histopathological changes between contusion,distra ction,and dislocation spinal cord injuries in a rat model.We found that contusion led to the most severe dorsal white matter injury and caused considerable attenuation of both somatosensory and motor evoked potentials.Dislocation resulted in loss of myelinated axons in the lateral region of the injured spinal cord along the rostrocaudal axis.The amplitude of attenuation in motor evoked potential responses caused by dislocation was greater than that caused by contusion.After distraction injury,extracellular spaces were slightly but not significantly enlarged;somatosensory evoked potential res ponses slightly decreased and motor evoked potential responses were lost.Correlation analysis showed that histological and electrophysiological findings we re significantly correlated and related to injury type.Intraope rative monitoring of both somatosensory and motor evoked potentials has the potential to identify iatrogenic spinal cord injury type during surgery.

Observing the steady-state visual evoked potentials with a compact quad-channel spin exchange relaxation-free magnetometer

We observed the steady-state visually evoked potential(SSVEP) from a healthy subject using a compact quad-channel potassium spin exchange relaxation-free(SERF) optically pumped magnetometer(OPM). To this end, 30 s of data were collected, and SSVEP-related magnetic responses with signal intensity ranging from 150 fT to 300 f T were observed for all four channels. The corresponding signal to noise ratio(SNR) was in the range of 3.5–5.5. We then used different channels to operate the sensor as a gradiometer. In the specific case of detecting SSVEP, we noticed that the short channel separation distance led to a strongly diminished gradiometer signal. Although not optimal for the case of SSVEP detection, this set-up can prove to be highly useful for other magnetoencephalography(MEG) paradigms that require good noise cancellation.Considering its compactness, low cost, and good performance, the K-SERF sensor has great potential for biomagnetic field measurements and brain-computer interfaces(BCI).

Effect of sodium tungstate on visual evoked potentials in diabetic rats

AIM: To evaluate the effect of sodium tungstate on visual evoked potentials(VEPs) in diabetic rats.· METHODS: Wistar rats were randomly divided into three groups as normal control, diabetic control and diabetic rats treated with sodium tungstate. Diabetes was induced by single intraperitoneal injection of streptozotocin(50 mg/kg). Sodium tungstate [40 mg/(kg·d)]was administered for 12 wk and then VEPs were recorded.Additionally, thiobarbituric acid reactive substance(TBARS) levels were measured in brain tissues.·RESULTS: The latencies of P1, N1, P2, N2 and P3 waves were significantly prolonged in diabetic rats compared with control group. Diabetes mellitus caused an increase in the lipid peroxidation process that was accompanied by changes in VEPs. However, prolonged latencies of VEPs for all components returned to control levels in sodium tungstate-treated group. The treatment of sodium tungstate significantly decreased brain TBARS levels and depleted the prolonged latencies of VEP components compared with diabetic control group.· CONCLUSION: Sodium tungstate shows protective effects on visual pathway in diabetic rats, and it can be worthy of further study for potential use.

Specificity and sensitivity of visual evoked potentials P100 latency to different events exercise

Visual evoked potentials (VEPs) are a series of signals about visual occipital cortex in response to visual stimuli and can be used as one of ob-jective non-invasive neuro-physiological pa-rameters to reflect the visual organs and central visual pathway’s functional integrity. Previous studies have shown that acute and chronic ex-ercise could affect VEPs independent from body temperature and other physiological parameters. VEPs may well be used as neuro-physiological criteria in defining the performances of the ath-letes. Different sports training have different effects on VEPs, but the results are not consis-tent. P100 latency is the representative compo-nent of VEPs and it is of high, steady amplitude and of slight intra- and inter-individual variabil-ity so that the index is most commonly used. The purpose of this study was to investigate the specificity and sensitivity of P100 latency to dif-ferent physical activities. The neural electricity device of NDI-200 was used to measure the pattern reversal VEPs of all subjects, including the values of the resting state before and after different events exercise. Different events exer-cise contained an aerobic cycloergometric ex-ercise (7 subjects were conducted to a Bruce Graded Exercise Test on the Monark Ergomedic 839E cycloergometer, THR (target heart rate) = 85% HRmax, 3 times/week, about 10 minutes once time, 6 weeks), tennis training (16 volun-teers, 2 hours/day, 3 days/week, 8 weeks), aerobic Latin exercise (7 subjects, 1 hour/day, 3 days/week, 6 weeks) and the Baduanjin of Health Qigong training (6 subjects, 1 hour/day, 3 days/week, 6 weeks). The VEPs recordings of the control groups obtained synchronized with the experimental groups. SPSS 11.5 for win-dows was used for statistical analysis. A level of P﹤0.05 was accepted as statistically significant. The VEPs P100 latency of post-exercise of all experimental groups except Baduanjin group became shorter significantly compared with those of pre-exercise (P﹤0.05). No significant difference was found between pre-and post- exercise for the control groups. This study showed that exercise could shorten the P100 la-tency significantly. Moreover, it also indicated that VEPs were sensitive to exercise to a certain extent. We concluded that VEPs might well be used as neuro-physiological criteria in defining the performances of the athletes. It was found that the VEPs P100 latency became shorter after most training programs;furthermore, it demon-strated that P100 latency of VEPs had little specificity to different events.

EFFECTS OF ACUPUNCTURE ON SENSORY EVOKED CORTICAL POTENTIALS IN RABBITS

The effects of acupuncture on the sensory evoked cortical potentials were investigated in 31 rabbits anaesthetized with urethane of conscious, so as to see what happened to the functional state of cerebral cortex in the meantime. The visual, auditory and somatosensory evoked potentials as well as raw EEGs were recorded from the animal’s scalp. In most cases, an electro-acupuncture instrument was used instead of manual acupuncture. The main component amplitudes of evoked potentials,the frequency band powers and the total integral values of raw EEGs were analyzed. Results showed that during acupuncture the main components of evoked potentials were significantly depressed and the raw EEGs appeared desynchronized while the experimental animals were slightly activated. Moreover,both the total integral values of raw EEGs and the powers of lower frequency waves (1 - 3. 99 Hz)were decreased and positively correlated well with the amplitudes of main components of the evoked potentials. Therefore, the possibility that the effects of acupuncture on the evoked potentials are secondary to the changes of raw EEGs remains to be ruled out, and it is suggested that the inhibition of evoked potentials during acupuncture does not necessarily mean that the cerebral cortex is in an inhibitory

Vestibular-evoked myogenic potentials recorded from miniature pigs and rats

Objective:To report vestibular evoked myogenic potentials from different recording sites(neck extensor or masseter muscles) in miniature pigs and rats.Methods:Potentials were recorded using 1000 Hz tone bursts from the neck extensor muscle or masseter muscle in normal adult Bama miniature pigs and rats anesthetized with 3%pentobarbital sodium and Sumianxin Ⅱ.Results:At 80 dB SPL,the first positive wave(P wave) of VEMPs was recognizable in 58%of rats with a latency of 6.45±0.23 ms and an amplitude of 1.45±0.49 μV when recorded from the neck extensor muscle,and in 50%of rats with a latency of 6.38±0.34 ms and an amplitude of 1.57±0.35 μV when recorded from the masseter muscle.In miniature pigs,at the same stimulus intensity,P wave was recognizable in 58%of the animals with a latency of 7.65±0.64 ms and an amplitude of 1.66±0.34 μV when recorded from the neck extensor muscle,and in 50%of the animals with a latency of 7.65±0.64 ms and an amplitude of 0.31±0.28 μV when recorded from the masseter muscle.Conclusion:VEMP can be induced from both neck extensor and masseter muscles in the miniature pig and rat.For a given species,the site of recording affects P wave induction rate and amplitude but not latency.Consistency and repeatability analysis suggests that the masseter muscle is a better recording site in miniature pigs while the cervical extensor is a better recording site in rats.For a given recording site,both latency and amplitude of the P wave are slightly greater in miniature pigs than in rats.

Vestibular evoked myogenic potentials in patients with diabetes mellitus

Although the exact mechanism and most involved region of the vestibular system have not yet been fully clarified, vestibular dysfunction has been demonstrated in patients with diabetes mellitus (DM). Vestibular evoked myogenic potential (VEMP) is a short latency electromyographic response to sound or vibration stimuli that may reflect otolith organ or related reflex functions. Since its first description in 1992, VEMP has become a significant part of the vestibular test battery as an objective measurement tool. In diabetic patients, VEMP responses have been studied in order to determine any otolith organ or related reflex dysfunctions. Here, we review the literature with regard to VEMP findings representing any peripheral vestibular end-organ dysfunction in patients with DM. Distinctive vestibular end-organ impairments seem to be demonstrated in patients with DM either with or without DNP via objective vestibular testing tools including VEMP recordings according to relevant studies. However, further studies with larger sample sizes are required to reveal the more definitive findings of VEMP recordings regarding the vestibular pathologies in patients with DM.

Brainstem auditory evoked potentials in patients with delayed encephalopathy after acute carbon monoxide poisoning

Objective:To evaluate the changes of brainstem auditory evoked potential (BAEP) in patients with delayed encephalopathy after acute carbon monoxide poisoning. Methods: BAEPs were performed in 32 controls and 40 patients. Wave Ⅰ , Ⅱ , Ⅲ ,Ⅳ, Ⅴ latencies and Ⅰ-Ⅲ , Ⅲ-Ⅴ , Ⅰ-Ⅴ interpeak latencies were measured, respectively. Results: Abnormalities of BAEPs in 13 patients (13/40, 32 ％). Among the13 abnormal BAEPs, 3 displayed prolongation of latency to waves in one side, no potential in another side; 5 displayed a similar abnormality which was bilateral prolongation of latency to waves ;and another 5 displayed unilateral latency delay. Compared wave Ⅰ , Ⅱ , Ⅲ , Ⅳ, Ⅴ latencies and Ⅰ-Ⅲ , Ⅲ-Ⅴ , Ⅰ-Ⅴ interpeak latencies in the patients and the controls, there were no significant differences (P＞0.05). Conclusion: BAEPs can be used for evaluating the diagnostic and prognostic values in the cases of delayed encephalopathy after acute carbon monoxide poisoning.

Evaluation of ocular and cervical vestibular evoked myogenic potentials in a conductive hearing loss model

Objective: To investigate the effects of conductive hearing loss(CHL) on vestibular evoked myogenic potentials(VEMPs) using a simulated CHL model, and to provide the basis for future studies.Methods: Twenty-one healthy subjects were recruited in this study. We measured ocular VEMPs(o VEMPs) and cervical VEMPs(c VEMPs) in these subjects by air-conduction sound(ACS) stimulation. CHL was simulated later by blocking the right external auditory canal with a soundproof earplug to evaluate its impacts on VEMPs. Subjects' responses before simulated CHL served as the control, and were compared to their responses following simulated CHL.Results: o VEMPs following simulated CHL showed decreased response rate, elevated thresholds, attenuated amplitudes and prolonged N1 latencies compared with those before simulated CHL, and the differences were statistically significant. Similarly, c VEMPs following simulated CHL also showed decreased response rate, elevated thresholds and attenuated amplitudes, with prolonged P1 latencies compared with those before simulated CHL, although only differences in response rate, threshold and amplitude were significant.Conclusions: Conductive hearing loss affects the response rate and other response parameters in o VEMPs and c VEMPs.

Clinical application of electrically evoked compound action potentials

ECAPs are the summary of multiple neurons' spikes which could be recorded by a bidirectional stimulation-recording system via the cochlear implant,with the artifact elimination paradigms of forward-masking subtraction paradigm or alternating polarity paradigm.Three kinds of FDA approved cochlear implants support ECAP testing.This article is to summarize the clinical application of ECAP lest.ECAP test after insertion of electrode during implant operation has been widely used during cochlear implant surgery.In recent years.ECAP thresholds are also used to estimate the T levels and C levels helping programming.However,correlation between ECAP thresholds and psychophysical thresholds is affected by many factors.So far,ECAPs cannot yet be a good indicator of post-operative hearing and speech performance.

The mechanisms underlying long-term potentiation of C-fiber evoked field potentials in spinal dorsal horn

Long-term potentiation(LTP) of C-fiber evoked field potentials in spinal dorsal horn is first reported in 1995.Since then,the mechanisms underlying the long-lasting enhancement in synaptic transmission between primary afferent C-fibers and neurons in spinal dorsal horn have been investigated by different laboratories.In this article,the related data were summarized and discussed.

Changes in the latencies of visual-evoked potentials in people undergoing tennis training Dynamic comparison before and after 8 weeks training

BACKGROUND: Some previous studies have shown that exercise is an important factor that affects the latencies of visual-evoked potentials (VEPs). OBJECTIVE: To investigate the effects of spending a period of time undergoing tennis training on the latencies of VEPs by comparing the latencies of VEPs before tennis training with those after 8 weeks of tennis training. DESIGN, TIME AND SETTING: The non-randomly concurrent controlled experiment was performed in the Department of Human Movement Sciences, Physical Education College, Shandong Normal University from April to June 2007. PARTICIPANTS: In total, 45 healthy volunteers from Shandong Normal University were selected as subjects, including 31 students majoring in physical education (11 males and 5 females participated in the tennis training plan for 8 weeks), and 14 students from other subjects. Informed consent was obtained. According to whether they were majoring in physical education or not, and whether or not they took part in tennis training, the students were divided into 3 groups: a tennis group of physical education students (n =16), a non-tennis group of physical education students (n =15) and a non-tennis group of non-physical education students (n =14). METHODS: The subjects in the tennis group took part in a regular tennis training plan of 2 hours a day and 3 days per week, for 8 weeks, while the subjects in two non-tennis groups were not in the tennis training plan. The NDI-200 neural electricity tester (Shanghai Haishen Medical Electronic Instrument Co., Ltd.) was used to measure VEPs before and after the experiment in all three groups, and to compare the latencies of VEPs recorded before training with those recorded after training. MAIN OUTCOME MEASURES: Comparison of the changes in latencies of VEPs before and after 8 weeks of tennis training. RESULTS: All 45 subjects finished the test and datas from all were included in the statistical analysis. There were no significant differences among all the three groups before tennis training, but the female subjects in each group showed significantly shorter N75 latencies than male subjects of the same group (P < 0.05). Comparing the latencies of VEPs after training with those recorded before training, the N75, P100 and N145 latencies were all found to be significantly shorter than before training in the tennis group (P < 0.05), but the N75, P100 and N145 latencies were unaffected in the two non-tennis groups (P > 0.05); some latencies were even significantly longer than the before-training values. CONCLUSION: Special tennis training for 8 weeks can make the subjects’ VEP latencies significantly shorter. Thus, VEP latencies can change with tennis training.

Application of pudendal evoked potentials in diagnosis of erectile dysfunction

Aim: Extensive neurophysiological investigations were carried out in I00 healthy subjects and 84, patients with penile erectile dysfunction.

A study on vestibular-evoked myogenic potentials via galvanic vestibular stimulation in normal people

Objectives: The aim of our study is to examine vestibular-evoked myogenic potentials(VEMPs) elicited by the galvanic vestibular stimulation in the sternocleidomastoid muscle(SCM) in healthy subjects for clinical applications of auditory neuropathy or vestibular neuropathy in the future.Methods: We enrolled sixteen healthy subjects to record the average responses of SCM to galvanic vestibular stimulation(GVS) [current 3 mA;duration 1 ms] by electromyography(EMG). SPSS 18.0 software was used to analyze the obtained data for mean and standard deviation.Results: In all healthy subjects mastoid-forehead galvanic vestibular stimulation produced a positive-negative biphasic EMG responses on SCM ipsilateral to the cathodal electrode. The latency of p13 was 11.7 ± 3.0 ms. The latency of n23 was 17.8 ± 3.4 ms. The amplitude of p13-n23 was147.0 ± 69.0 μV. The interaural asymmetry ratio(AR) of p13, n23 latency and the amplitude was respectively 0.12 ± 0.09, 0.08 ± 0.08 and0.16 ± 0.10.Discussions: Galvanic vestibular stimulation could elicit biphasic EMG responses from SCM via the vestibular nerve but not from the otolith organs. Galvanic stimulation together with air conducted sound(ACS) or bone conducted vibration(BCV) can elicit VEMPs and may enable the differentiation of retrolabyrinthine lesions from labyrinthine lesions in vestibular system.

Benefits of combination of electroencephalography, short latency somatosensory evoked potentials, and transcranial Doppler techniques for confirming brain death

Objective: Optimization of combining electroencephalography (EEG), short latency somatosensory evoked potentials (SLSEP) and transcranial Doppler (TCD) techniques to diagnose brain death. Methods: One hundred and eleven patients (69 males, 42 females) from the major hospitals of Zhejiang Province were examined with portable EEG, SLSEP and TCD devices. Re-examinations occurred ≤12 h later. Results: The first examination revealed that the combination of SLSEP and EEG led to more sensitive diagnoses than the combination of SLSEP and TCD. Re-examination confirmed this and also revealed that the combination of TCD and EEG was the most sensitive. Conclusion: The results show that using multiple techniques to diagnose brain death is superior to using single method, and that the combination of SLSEP and EEG is better than other combinations.

Characteristics of brainstem auditory evoked potentials of students studying folk dance

BACKGROUND: Previous experiments have demonstrated that brainstem auditory evoked potential is affected by exercise,exercise duration,and frequency. OBJECTIVE: Comparing the brainstem auditory evoked potential of students studying folk dance to students studying other subjects. DESIGN: Observational contrast study. SETTING: Physical Education College,Shandong Normal University PARTICIPANTS: Fifty-five female students were enrolled at Shandong Normal University between September and December in 2005,including 21 students that studied folk dance and 34 students that studied other subjects. The age of the folk dance students averaged (19 ± 1) years and dance training length was (6.0 ± 1.5) years. The students that studied other subjects had never taken part in dance training or other physical training,and their age averaged (22 ± 1) years,body height averaged (162 ± 5) cm,body mass averaged (51 ± 6) kg. All subjects had no prior ear disease or history of other neurological disorders. All students provided informed consent for the experimental project. METHODS: The neural electricity tester,NDI-200 (Shanghai Poseidon Medical Electronic Instrument Factory) was used to examine and record Brainstem Auditory Evoked Potential values of the subjects during silence,as well as to transversally analyze the Brainstem Auditory Evoked Potential values. The electrode positions were cleaned and degreased with soapy water,followed by ethanol. The selected bipolar electrodes were situated on the head: recording electrodes were placed at the Baihui acupoint,and the reference electrode was placed at the mastoid of the measured ear,with grounding electrodes in the center of the forehead. Brainstem Auditory Evoked Potential values were elicited by monaural stimulation of a "click" though an earphone; the other ear was sheltered by the white noise. The click intensity was 102 db,the stimulation frequency was 30 Hz,the bandpass filters were 1 000-3 000 Hz,the sensitivity was 5 μV,and a total of 2 000 sweeps were averaged. Waveform identification and analysis: various components of the Brainstem Auditory Evoked Potential values were identified,and the peak latencies and peak-peak values were analyzed. MAIN OUTCOME MEASURES: Latency of Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ and Peak-Peak Value of Ⅰ,Ⅲ,Ⅴ were measured. RESULTS: Fifty-five subjects were enrolled in the final analysis,without any loss. Compared to the students who studied other subjects ①Ⅰ-Ⅴ peak latencies (PL): Ⅳ PL of the right ear of the folk dance students was obviously longer (P < 0.05); ②Ⅰ,Ⅲ,Ⅴ peak-peak values: Ⅰ peak-peak values of the right ear were obviously higher (P < 0.05). CONCUSION: ① PL of the right ear of the folk dance students was obviously longer,which indicates that dancing results in a stronger sensibility to auditory stimuli. ②P?eak-peak values were obviously higher,which indicates that long-term exercise enhances the music senses and synchrony of auditory nerve impulses.

Vestibular-evoked myogenic potentials in miniature pigs

Objective: To report detection of vestibular-evoked myogenic potentials(VEMPs) in the miniature pig.Methods: Potentials evoked by 1000 Hz tone bursts were recorded from neck extensor muscles and the masseter muscles in normal adult Bama miniature pigs anesthetized with 3% pentobarbital sodium and Carbachol II.Results: The latency of the first positive wave P from neck extensor muscles was 7.65 ± 0.64 ms, with an amplitude of 1.66 ± 0.34 uv and a rate of successful induction of 75% at 80 d B SPL. The latency of potentials evoked from the masseter muscles was 7.60 ± 0.78 ms, with an amplitude of 1.31 ± 0.28 uv and a rate successful induction of 66% at 80 d B SPL.Conclusion: The latencies and thresholds of VEMPs recorded from the neck extensor muscle and the masseter muscle appear to be comparable in normal adult Bama miniature pigs, although the amplitude recorded from the neck extensor muscle seems to be higher than that from the masseter muscle. However, because of their usually relatively superficial and easily accessible location, as well as their large volume and strong contractions, masseter muscles may be better target muscles for recording myogenic potentials.

On-Line Suppression of Periodic Noises in Evoked Potentials

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