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.

Monitoring somatosensory evoked potentials in spinal cord ischemia-reperfusion injury

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 potentia~ ~atency can reflect the degree of spinat 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.

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.

Short-duration transient visual evoked potentials and color reflectivity discretization analysis in glaucoma patients and suspects

AIM： To evaluate the use of short-duration transient visual evoked potentials（VEP） and color reflectivity discretization analysis（CORDA） in glaucomatous eyes,eyes suspected of having glaucoma,and healthy eyes.METHODS： The study included 136 eyes from 136 subjects： 49 eyes with glaucoma,45 glaucoma suspect eyes,and 42 healthy eyes.Subjects underwent Humphrey visual field（VF） testing,VEP testing,as well as peripapillary retinal nerve fiber layer optical coherence tomography imaging studies with post-acquisition CORDA applied.Statistical analysis was performed using means and ranges,ANOVA,post-hoc comparisons using Turkey＇s adjustment,Fisher＇s Exact test,area under the curve,and Spearman correlation coefficients.RESULTS： Parameters from VEP and CORDA correlated significantly with VF mean deviation（MD）（P〈0.05）.In distinguishing glaucomatous eyes from controls,VEP demonstrated area under the curve（AUC） values of 0.64-0.75 for amplitude and 0.67-0.81 for latency.The CORDA HR1 parameter was highly discriminative for glaucomatous eyes vs controls（AUC=0.94）.CONCLUSION： Significant correlations are found between MD and parameters of short-duration transient VEP and CORDA,diagnostic modalities which warrant further consideration in identifying glaucoma characteristics.

Determination of Median Nerve Somatosensory Evoked Potentials in 27 Patients with Hemiplegia

Summary: Twenty-seven in-patients with hemiplegia following brain injury were studied by using upper extremity median nerve somatosensory evoked patentials (SVEP), Brunnstrom assessment in hemiplegic hand and assessment of the patients' activities of daily lioing (ADL) (Barthel index). The upper extremity median nerve SEP on the affected and normal sides was determined. By using Kovindha standard, upper extremity median nerve SEP was graded in accordance with N20. The correlation between the differences of SEP N20 amplitude and the latencies on the both sides and the Barthel index scores was analyzed. A Spearman correlation analysis was made between the median nerve SEP N20 grades and Brunnstrom stages in hand or ADL on the affected side. The results showed that upper extremity median nerve SEP grades were positively correlated with those of the Brunnstrom stages in hand (r 1=0.6925, P 1<0.01). The correlation coefficient between SEP N20 grades and patients' ADL grades was r 2=0.5015, P 2<0 01. It was concluded that upper extremity median nerve SEP could be used as a sensitive electrophysiological predictor to clinically assess hemiplegic hand function. SEP N20 might play a role in predicting the ADL of the patients with hemiplegia to some extent, but could not be used as a sensitive predictor to directly observe and predict the ADL of the patients.

Normal values of flash visual evoked potentials in rabbits: Differences between the sexes and the eyes

BACKGROUND: The wave form, latency and wave amplitude of visual evoked potentials (VEP) are obviously affected by the stimulative parameters, physiological status of the subjects and anesthetics, thus there are greater normal variations and individual differences. The features of flash VEP (F-VEP) are to be observed. OBJECTIVE: To observe and compare the differences of F-VEP latencies and wave amplitudes between eyes in rabbits, and investigate the correlation with sex and the side of eyes. DESIGN: A comparative animal experiment. SETTING: Department of Neurosurgery, General Hospital of Chinese PLA. MATERIALS: The experiment was carried out in the neurophysiological laboratory of the Institute of Neurosciences, General Hospital of Chinese PLA from September 2004 to February 2005. Thirty big-ear rabbits of clean degree, 15 males and 15 females, weighing 2.0-2.5 kg, were provided by the animal center of the General Hospital of Chinese PLA. METHODS: Viking-IV perioperative monitor and flash stimulator for special use were applied. The rabbits were anesthetized with intramuscular injection of compound ketamine. The recording electrode was placed at 3 mm anterior to exoccipital tuberosity (onion, Oz), and the reference electrode was placed at the ear edge of the same side. The stimulative frequency was 1.9 Hz, and the amplifier was 50 μV; The range of wave filter was 5 Hz for high pass and 100 Hz for low pass; The average overlapping was 200 times, and the analytical time was 250 ms. MAIN OUTCOME MEASURES: Comparison of F-VEP wave forms; F-VEP latencies and wave amplitudes. RESULTS: All the 30 rabbits were involved in the analysis of results. ① Comparison of F-VEP wave forms in rabbits: The F-VEP waves mainly manifested as positive-negative-positive (PNP). The F-VEP manifestations to light stimulations were extremely similar between left and right eyes, and the wave amplitudes of both eyes were obviously increased. ② Determinations of F-VEP latencies and wave amplitudes: There were no significant differences in the latencies and wave amplitudes of F-VEP between the two groups (P > 0.05), the latencies of P1, N1 and P2 waves of left eye were (32.59±2.01), (43.85±4.35) and (66.20±8.13) ms, respectively, and the wave amplitudes of P1, N1 and P2 waves of left eye were (16.45±10.22), (7.93±3.56) and (17.62±8.18) μV. F-VEP latencies were stable with small changes, whereas amplitudes had greater changes. CONCLUSION: ① The latency and wave amplitudes F-VEP were stable with good repetition. ② The latencies and wave amplitudes had no significant differences between males and females, as well as between left and right eyes. Further investigation should be undertaken on the animal and clinical field.

Test-Retest Reliability of Sensory Evoked Potentials in Low-Functioning Autism: A Case Report

Sensory abnormalities are common in individuals with autism spectrum disorders (ASD) but are often difficult to assess using standard behavioral methods. Evoked potentials provide objective, non-invasive electrophysiological measures of neural sensory processing that could be useful for clinical and investigative studies of individuals with low-functioning autism who are unable to perform behavioral testing. Despite increased use, the reliability of sensory evoked potentials has not been established for individuals with low-functioning autism. Establishing reliability is important for validating the utility of sensory evoked potentials. In this study, we explored the feasibility of assessing the test-retest reliability of sensory evoked potentials using repeat recordings, acquired over 2.5- and 6-month intervals, from a minimally verbal adult with low-functioning autism. Repeat auditory and visual evoked potential recordings showed high test-retest reliability, with cross-correlation coefficients ≥ 0.80. This case demonstrates the feasibility of establishing test-retest reliability for individuals with low-functioning autism and supports the utility of sensory evoked potentials in clinical and investigative ASD studies.

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

Objective： To evaluate the diagnostic and prognostic values in patients with delayed encephalopathy after acute carbon monoxide poisoning. Methods： The tibial nerve somatosensory evoked potentials （SEPs）, vision evoked potentials （VEPs）, and brain stem audition evoked potentials（BAEPs） were performed in 32 healthy adults and 43 patients with delayed encephalopathy after acute carbon monoxide poisoning. Results： This paper indicated abnormalities of tibial nerve SEPs in 31 patients （31/43, 72.1%）, VEPs in 17 patients （17/28, 60.7%）, and BAEPs in 14, patients （14/43, 32.6%）. These results showed that the greatest diagnostic value was SEPs, followed by VEPs and, BAEPs with the lowest sensitivity. Conclusion： Multimodality evoked potentials （EPs） can be used for evaluating the diagnostic and prognostic values in cases of delayed encephalopathy after acute carbon monoxide poisoning.

Dermatomal Somatosensory Evoked Potentials: An Indicator of Improvement of Breast Sensibility after Reduction Mammaplasty

Introduction: Many women think about reduction mammaplasty for different reasons. The effect of surgery on the beast sensibility is one of the greatest concerns after reconstructive reductive breast surgery through its affect on patient’s social life and psychological health. The dermatomal somatosensory evoked potential (D-SEP) is a new method to quantitatively evaluate breast sensibility. Patients and Methods: Twenty-five women enrolled in this study presenting with breast enlargement, underwent mammary reduction by using the inferior pyramidal breast reduction technique using the same operative technique described by Robbins with some modifications. All D-SEP amplitudes and latencies were calculated preoperatively and then were reassessed six and twelve months post-surgery in each breast. Result: The results revealed that there is a significant difference in the D-SEP latency pre- and post-operatively. The statistically significant decrease in latency and the breast size demonstrated indicates that the sensibility improved after breast reduction surgery both at six and twelve months. There is also a significant increase in the D-SEP amplitude pre- and post-operatively. The negative and statistically significant increase in amplitude with the decrease in breast size demonstrated indicates that the sensibility improved after breast reduction surgery both at six and twelve months. Conclusion: This study concluded that breast sensibility will improve after breast reduction as indicated by significant reduction of D-SEP latencies and increase of its amplitudes. Our results confirm an inverse relationship between breast size and sensibility, with improvement in sensibility after breast reduction.

EXPERIMENTAL AND CLINICAL STUDY ON BILIRUBIN NEUROTOXICITY DETECTED BY VISUAL EVOKED POTENTIALS TO FLASH

Objective Evaluate the sensitivity and reliability of visual evoked potential to flash (F-VEP) in detecting bilirubin neurotoxicity and approach the risk parameters of bilirubin neurotoxicity in hyper-bilirubinemia newborns. Methods Based on the successful establishment of animal models for acute bilirubin encephalopathy by intraperitoneal infusion of bilirubin with a dosage of 100～200μg/g body weight to 1-week-old guinea pigs, the F-VEP was recorded in animal models and human neonates with hyperbilirubinemia, and the sensitivity and reliability of F-VEP in detecting bilirubin neurotoxicity were evaluated. Results F-VEP features and its P1 latency significantly correlated to brain adenosine triphosphate (ATP) level, neurobeha-vioral and neuropathological changes in experimental bilirubin encephalopathy; neonates with hyperbiliru-binemia showed significant F-VEP changes characterized by absence of P1 or P1 latency prolonged in 1～7-day-old newborns, especially when the jaundice was caused by immun oincompatibility and infectious diseases. Conclusion F-VEP would be a good discriminator for bilirubin neurotoxicity, and can become a promising technique in monitoring bilirubin encephalopathy.

CLINICAL STUDY OF MOTOR EVOKED POTENTIALS BY MAGNETIC STIMULATION IN CERVICAL SPONDYLOTIC MYELOPATHY

The combined use of motor .yoked pot'ntlais (MEPs) with F way, recording was cornpared with somatesemory evoked potentials (SEPs) in order to evaluate the clinical value or MEPs incervical spondylotic myelopathy. Magnetic stimulation of motor cortex with F wave recording was used assess central motor conduction. time, (CMCT). and central somatoseusory conduction time(CSCT)was evaluated by SEPs in 20 pailents surffring from myeloP8thy of cervical spondylosis. Theresults were comapared with 20 control subjects. The results showed that CMCT of Patients was obviously prolonged then that of contral subjects, the sbnormal rate was 80% which was higher than70K of SEPs slid that the prolongation or CMCT had a good correlation with the severe degree ofmyelopathy. The Painless and noninvasive .magnetic stimulation of PEPs could figure out the compressed degree of motor descending pathway and was. useful technique for diagnosis of cervicalspondylotic myelopathy.

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 ta V, 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, Ⅴwere measured. RESULTS： Fifty-five subjects were enrolled in the final analysis, without any loss. Compared to the students who studied other subjects ① Ⅰ -Ⅴ peak latencies （PL）： Ⅳ PL of the right ear of the folk dance students was obviously longer （P 〈 0.05）; ② Ⅰ, 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. ②. Peak-peak values were obviously higher, which indicates that long-term exercise enhances the music senses and synchrony of auditory nerve impulses.

Changes in somatosensory evoked potentials elicited by stimulation of upper-limb and lower-limb nerves in amyotrophic lateral sclerosis patients

This study observed the changes in somatosensory evoked potentials between patients with amyotrophic lateral sclerosis （ALS） and healthy controls to evaluate the function of the central deep somatosensory pathway. In patients with ALS, 28 patients （54%） showed an abnormality in somatosensory evoked potentials. All had abnormal lower limb somatosensory evoked potentials. Compared with healthy controls, the abnormality in somatosensory evoked potential was characterized by prolonged N20, P2, N2 latency and central conduction time, with or without a decrease in wave amplitude or disappearance of waveform. Results showed marked alterations in the somatosensory evoked potential in cortical components of the upper and lower limb in 54% of patients with ALS, and confirmed that patients with ALS may also have a defective deep somatosensory pathway, particularly an abnormal central deep somatosensory pathway.

Enhanced auditory evoked potentials in musicians:A review of recent findings

Auditory evoked potentials serve as an objective mode for assessment to check the functioning of the auditory system and neuroplasticity.Literature has reported enhanced electrophysiological responses in musicians, which shows neuroplasticity in musicians. Various databases including Pub Med, Google, Google Scholar and Medline were searched for references related to auditory evoked potentials in musicians from 1994 till date. Different auditory evoked potentials in musicians have been summarized in the present article. The findings of various studies may support as evidences for music-induced neuroplasticity which can be used for the treatment of various clinical disorders. The search results showed enhanced auditory evoked potentials in musicians compared to non-musicians from brainstem to cortical levels. Also, the present review showed enhanced attentive and pre-attentive skills in musicians compared to non-musicians.

Effect of Wei’s triple nine needling therapy on flash visual evoked potentials in rats with traumatic optic neuropathy

Objective:To investigate the effect of Wei’s triple nine needling therapy on the N2-P2 wave of the flash visual evoked potential(FVEP)in rats of the of the transverse directional pulling model.Methods:Thirty-six Wistar rats were randomly grouped,nine were in normal control group without any treatment,and the remaining 27 were surgically modelled in the right eyes.Eighteen of these rats were randomly divided into a Wei’s triple nine needling therapy group and a model group of nine rats each after the TON model was made using the transverse quantitative retraction method.The other 9 rats were sham-operated,and only the optic nerve was exposed without retraction.On the next day of modelling,the Wei’s triple nine needling therapy group was treated with Wei’s triple nine needling therapy for 20 minutes/1 time/1 day for 14 days.The model group,sham-operated group and normal control group were not intervened.Wei's triple nine acupoints were represented as follows:1st link:"Jingming"(BL1)and"Chengqi"(ST1);2nd link:"Sizhukong"(SJ23)penetrating"Taiyang"(EX-HN5);and the third:"Fengchi"(GB 20)and"Taichong"(LV3).The FVEP of each group was observed on 1d,7d and 14d.The FVEP of each group was observed on 1d,7d and 14d.Results:Compared with the model group,the N2 wave latency and P2 wave latency were shortened in the Wei’s triple nine needling therapy on 1d(P<0.05,P<0.01);on 7d,their N2 wave latency was shortened(P<0.01)and the N2-P2 wave amplitude was increased compared with the model group(P<0.05);on 14d,their P2 wave latency was shortened(P<0.05)and the N2-P2 wave amplitude was increased.There was no statistical difference in N2 wave latency,P2 wave latency and N2-P2 wave amplitude in the sham-operated group on 1d,7d and 14d(P>0.05).The delayed N2 and P2 wave latencies in the model group did not improve from 1d to 14d(P>0.05)and the amplitude decreased throughout,showing a significant difference on 14d compared to 1d(P<0.05).In contrast,the N2 wave latency in Wei’s triple nine needling therapy group was not significantly different until 7d to 14d(P<0.05);its P2 wave latency,although significantly delayed from 1d to 7d(P<0.05),recovered on 14d and reached a level that was not statistically different from 1d and 7d(P>0.05).There was also no significant decrease in N2-P2 wave amplitude between 1d and 14d in Wei’s triple nine needling therapy group(P>0.05).Conclusion:In this experiment,the TON rat model was successfully established by the transverse quantitative retraction method,and the treatment of TON rats with Wei’s triple nine needling therapy reduced the P2 wave delay of the FVEP electrophysiological signal and increased the N2-P2 amplitude,which had a certain positive effect on the repair of optic nerve injury,probably related to its effect of improving the conduction function of the optic nerve and protecting the retinal ganglion cells that had not been degenerated and necrosed.

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.

Value of somatosensory evoked potentials in diagnosis, surgical monitoring and prognosis of cervical spondylotic myelopathy

Background The value of somatosensory evoked potentials （SEPs） in the diagnosis and prognosis of cervical spondylotic myelopathy, as well as the usefulness of monitoring intraoperative potentials in terms of safety and predictive factors were investigated. Methods Each of the 76 myelopathic patients underwent surgical intervention. According to the wave configurations of the SEPs, the cases were categorised into four groups： Type Ⅰ, Ⅱ, Ⅲ and Ⅳ. The clinical myelopathy disability was classified and the severity of neurological deficits was scored. Clinical function after surgery was evaluated. Preoperative potentials and intraoperative monitoring were categorized. The correlations between .evoked potentials detection, monitoring, myelopathy disability and surgical outcome in the different groups were discussed. Results According to the configurations of the SEPs, there were 27 patients （36%） of Type Ⅰ, 30 patients （39%） of Type Ⅱ, 8 patients （11%） of Type Ⅲ, and 11 patients （14%） of Type Ⅳ. The categorised evoked potentials were shown to be significantly associated with the clinical representation of myelopathy （P 〈0.01） and the recovery rate from identifiable SEPs waves （groups A, B and C） was significantly higher than unidentifiable waves （group D, P〈0.01）. A deterioration of SEPs was detected in 23 cases （30%）, whereas there was no change in 40 cases （53%） and improvements in 13 cases （17%）. A significant difference in recovery rates could be observed in various monitoring groups within the short-term follow-up period, while there were no obvious differences in the long-term follow-up groups. Conclusions SEP technique is a valuable and practical tool for the diagnosis, monitoring and prognosis of myelopathy. Classified evoked potentials are well correlated with cervical spondylotic myelopathy disability, and unidentifiable SEPs waves in patients are indicative of a relatively poor outcome. In addition, intraoperative monitoring of SEPs plays an important role in protecting neural structures during cervical spine surgery.

Intraoperative facial motor evoked potentials monitoring with transcranial electrical stimulation for preservation of facial nerve function in patients with large acoustic neuroma

Background Although various monitoring techniques have been used routinely in the treatment of the lesions in the skull base, iatrogenic facial paresis or paralysis remains a significant clinical problem. The aim of this study was to investigate the effect of intraoperative facial motor evoked potentials monitoring with transcranial electrical stimulation on preservation of facial nerve function. Method From January to November 2005, 19 patients with large acoustic neuroma were treated using intraoperative facial motor evoked potentials monitoring with transcranial electrical stimulation （TCEMEP） for preservation of facial nerve function. The relationship between the decrease of MEP amplitude after tumor removal and the postoperative function of the facial nerve was analyzed. Results MEP amplitude decreased more than 75% in 11 patients, of which 6 presented significant facial paralysis （H-B grade 3）, and 5 had mild facial paralysis （H-B grade 2）. In the other 8 patients, whose MEP amplitude decreased less than 75%, 1 experienced significant facial paralysis, 5 had mild facial paralysis, and 2 were normal. Conclusions Intraoperative TCEMEP can be used to predict postoperative function of the facial nerve. The decreased MEP amplitude above 75 % is an alarm point for possible severe facial paralysis.

The effect of lead on brainstem auditory evoked potentials in children

To determine whether lead affects brainstem auditory evoked potentials (BAEPs) in low-to-moderate lead exposed children Methods BAEPs were recorded from 114 asymptomatic children aged 1-6 years Average values were calculated for peak latency (PL) and amplitude (Amp) Whole blood lead (PbB) levels were assessed by graphite furnace atomic absorption spectroscopy Based on their PbB levels, subjects were divided into low lead (PbB<100 μg/L) and high lead subgroups (PbB ≥100 μg/L) Results The PbB levels of the 114 subjects ranged from 32 0 to 380 0 μg/L in a positively skewed distribution The median of PbB levels was 90 0 μg/L while the arithmetic average was 88 0 μg/L Of the subjects, 43 0% (49/114) had levels equal to or greater than 100 μg/L Bilateral PLs Ⅰ, Ⅴ, and Ⅲ of the left ear in the high lead subgroup were significantly longer than those in the low lead subgroup (P<0 05) A positive correlation was found between PbB levels and bilateral PLs Ⅰ, Ⅴ and Ⅲ of the left ear (P<0 05), after controlling for age and gender as confounding factors A significant and positive correlation between PbB levels and PL Ⅰ of the left ear, even when PbB levels were lower than 100 μg/L, in the low subgroup (r=0 295, P=0 019) was also found Conclusions Lead poisoning in children younger than 6 years old is a very serious problem to which close attention should be paid The indications that lead prolongs partial PLs may imply that lead, even at PbB levels lower than 100 μg/L, impairs both the peripheral and the central portions of the auditory system BAEPs may be a sensitive detector of subclinical lead exposure effects on the nervous system in children