Evoked potentials

ABSTRACT- A survey is given of my studies of evoked potentials in patients with multiple sclerosis (MS) and in control subjects. Potentials were recorded following random low-rate auditory stimulation (BAEP), checkerboard pattern-reversal stimulation (VEP), somatosensory stimulation (SEP); blink reflexes (BR) were recorded following electrical stimulation of the supraorbital nerve. Normal data had to be related to age and sex in evaluating BAEPs and VEPs.
In 160 MS patients, a total of 421 recordings were obtained. Changes by repeated BAEP and VEP tests might reflect changes in the clinical state, but they also did occur in clinically stable patients. In patients with definite MS, high incidences of abnormality were shown, supporting the clinical findings. The diagnostic value was greatest when clinically silent lesions were demonstrated in patients with suspected or possible MS. In these patients, either BAEP or VEP gave evidence of subclinical lesions in about 50%, and when combined, in 71% of the patients, thus making a transfer to a more certain diagnostic classification possible and invasive examinations unnecessary. When SEP and BR tests were added, subclinical lesions were found in 74% of the patients. The SEP recordings did show a high incidence of abnormality, but only few silent lesions; the BR test was the least sensitive. The VEP was abnormal in all patients with signs of optic neuritis and in all but one with a history of optic neuritis.
The present results are compared to those obtained in other laboratories and with other types of examinations in MS patients. It is concluded that although the tests are not specific for MS, they give valuable information in the majority of patients with a clinically uncertain diagnosis. This information will most often not be given by other types of examination. The combination of VEP and BAEP is recommended, but it should be supplemented by SEP recording in patients without spinal signs.     

Visual, early auditory and somatosensory evoked potentials in multiple sclerosis (917 cases)

Visual (VEP), brainstem auditory (BAEP) and somatosensory (SEP) evoked potentials were recorded over a 6 year period in 917 patients with or suspected of multiple sclerosis according to Mc Alpine's criteria. Evoked potentials provided information of diagnostic relevance in detecting clinically unsuspected lesions (spatial dissemination). They also gave valuable informations in patients with atypical or borderline clinical features. When abnormal, VEP indicated clinically silent lesions in 45.1 p. 100 of patients with definite MS, 66 p. 100 of those with probable MS and 78 p. 100 of the possible MS. Less than 15 p. 100 of SEP and/or BAEP abnormalities were found in 83 patients with a simple or recurring retrobulbar optic neuritis. Thirteen patients with acute transverse myelopathy and no prior history of neurological disease were studied. All had normal visual and brainstem auditory evoked potentials. Abnormal VEPs helped to the clinical assessment of 88 patients with progressive spastic paraparesis 46,6 p. 100 of whom had abnormal VEPs demonstrating disseminated lesions and 36,1 p. 100 had abnormal BAEPs. The frequency of the various types of VEP, BAEP and SEP abnormalities was studied as well as their course on repeated recordings. Results of multivariate analysis are given. It was found that the longer the time interval between the first MS relapse and the evoked potential recording, the higher the incidence of abnormalities. The incidence of evoked potentials abnormalities was lower in patients with normal CSF and higher in patients with inflammatory CSF. The abnormalities were more frequent when patients had clinical evidence of lesions of the sensory pathways explored by the tests.     

Multimodal evoked potentials in neuro-Behçet: a longitudinal study of two cases

Two neuro-Behçet patients have been studied, over a period of several months, by means of peroneal and median somatosensory- (SEP), brainstem auditory- (BAEP), and visual- (VEP) evoked potentials. In both patients, peroneal SEP showed evidence of a pathological reduction in the central conduction velocity without a related deep sensation impairment, while VEP changes were consistent with the visual disorders. Conversely, BAEP and median SEP findings did not show disease-related abnormalities. The observed anomalies were detectable irrespective of the clinical phase of the disease. Thus, evoked potential assessment is useful in providing objective evidence for evaluating and monitoring CNS damage in neuro-Behçet's syndrome.     

卡马西平对诱发电位的影响及意义

目的研究长期口服卡马西平治疗癫对诱发电位的影响,并讨论其意义。方法选择尚未治疗的癫病人31例作为试验组;以性别、年龄与癫组相匹配的健康正常人26例作为对照组。两组先分别做脑干听觉诱发电位(BAEP)、事件相关电位P300、视觉诱发电位(VEP)和体感诱发电位(SEP),之后癫组开始卡马西平治疗,服药一年后再作上述各项检查。结果癫组病人治疗前各项电生理学指标与正常对照组相比无显著性差异;癫组卡马西平治疗后各项电生理指标与治疗前相比BAEP各波、P300以及VEP的P100波潜伏期均显著延长;SEP的潜伏期无显著变化。结论神经电生理学检查可以早期发现长期服用卡马西平导致的亚临床毒性。     

The value of brain stem auditory, visual and somatosensory evoked potentials and blink reflexes in the diagnosis of multiple sclerosis

Cervical and cortical somatosensory evoked potentials (SEP) following electrical stimulation of the median nerve and blink reflexes (BR) following electrical stimulation of the supraorbital nerve were recorded in 30 normal subjects aged 20–49 years. Subjects aged 40–49 had longer SEP latencies than subjects aged 20–39 years.
A total of 29 slightly affected patients with multiple sclerosis (MS) aged 26–49 years, including four patients without clinical signs (suspected MS) and 19 patients with signs indicating only one lesion (possible MS) were examined by low-rate random-stimulated brain stem auditory (BAEP), checkerboard pattern-reversal visual evoked potentials (VEP), SEP and BR. Abnormal recordings by at least one of the examinations were found in all but three patients, and by all four tests in five patients.
In patients with definite or probable MS, demonstration of clinically recognized or subclinical lesions was of minor diagnostic value, in contrast to the importance such findings had in patients with suspected or possible MS. Silent lesions were shown by at least one of the tests in the four suspected and in 13 of the possible MS patients, so these 17 patients could be transferred to a more certain diagnostic category. This reclassification was most often due to the BAEP recording.
In patients with spinal signs, the combination of BAEP and VEP recording was sufficiently efficient. In patients with optic neuritis a combination of BAEP and SEP was preferred. No abnormal recordings were found in 15 normal subjects examined by all four tests.     

Brain-stem auditory evoked potentials in multiple sclerosis: the relation to VEP,SEP and CSF immunoglobulins

Summary One hundred patients with multiple sclerosis (MS) were analysed retrospectively with respect to investigations of brain-stem auditory evoked potentials (BAEP), pattern reversal visual evoked potentials (VEP), somatosensory evoked potentials (SEP), and cerebrospinal fluid immunoglobulins (CSF-IG). BAEP were abnormal in 42% of those with normal VEP and SEP examinations, and in 38% of patients with normal CSF-IG. The chance of obtaining at least one abnormal EP was lower in patients with normal CSF-IG than in patients with abnormal CSF. When a dispersion ratio was included in the criteria for BAEP abnormality, the sensitivity increased compared with conventional BAEP criteria. We recommend that BAEP should still be included in the EP test battery for patients with suspected MS.     

多发性硬化患者的MRI及多种诱发电位研究

目的探讨磁共振成像(MRI)和诱发电位(EPs)在诊断多发性硬化中的价值。方法对68例多发性硬化患者的头颅MRI、脑干听觉诱发电位、视觉诱发电位以及体感诱发电位等指标进行回顾性分析和比较。结果多发性硬化患者的头颅MRI、脑干听觉诱发电位、视觉诱发电位以及体感诱发电位的异常率分别为91.2%(62/68)、80.9%(55/68)、82.4%(56/68)和77.9%(53/68),且均发现多发性硬化的亚临床病灶;两项或多项联合检查的异常率较单项检查的异常率增高,差异有统计学意义(P<0.01)。结论头颅MRI和诱发电位检查有助于临床早期确诊多发性硬化,联合应用可使其敏感性提高。     

Somatosensory and brainstem auditory evoked potentials in neurodegenerative system disorders

Brainstem auditory (BAEP) and somatosensory (SEP) evoked potentials to median and peroneal nerve stimulation were investigated in 25 patients with neurodegenerative system disorders: 9 Friedreich's ataxia, 7 hereditary motor sensory neuropathies, 3 familial spastic paraplegia, 3 olivopontocerebellar atrophy, 1 ataxia telangiectasia and 1 abetalipoproteinemia. BAEPs were abnormal in 39%, SEPs to both upper- and lower-limb stimulation were abnormal in 63%. Serial evoked potential testing paralleled the clinical progression. SEPs were more frequently and severely altered than BAEPs suggesting that SEP testing may be a more sensitive indicator of early involvement of afferent pathways in these disorders.     

Friedreich''s ataxia: clinical involvement and evoked potentials

In 15 patients definitely affected by Friedreich's ataxia, precocious SEP abnormalities were constantly recorded independent of the duration of symptoms and the severity of clinical involvement; VEPs were frequently involved, but neither VEP abnormalities, nor visual impairment could be correlated with the severity or duration of Friedreich's ataxia clinical involvement; BAEPs were, to different extents, abnormal. These were completely dissociated from hearing disorders and significantly correlated (P less than 0.001) with Friedreich's ataxia clinical disability. Our observation of increased latency of the VEP P100 component and the early disappearance of BAEP Wave V with persistence of Wave I is in contrast with the hypothesis that changes are related to primary axonal degeneration. For practical purposes SEPs could help in the early diagnosis of Friedreich's ataxia, and BAEPs could be used for the electrophysiological monitoring of its clinical progression.     

Adrenoleukodystrophy in the child and adrenomyeloneuropathy. Study of 2 families

Ten subjects from 2 families with adrenoleukodystrophy (ALD) and adrenomyeloneuropathy (AMN), hereditary X-linked diseases, were systematically explored. We performed endocrinological, biochemical assays and neurophysiological tests; the latter consisted of nerve conductions (CNV), Hoffmann's reflex and multimodal evoked potentials: visual (flash and pattern, VEP), brainstem auditory (BAEP) and somesthetic (SEP) using median nerve stimulation at the wrist. We only considered values above 2 SD. The purpose of our study was to determine the correlation between neurophysiological and endocrinological perturbations and the presence of pathological traits. Our results suggest that the correlation is high in diseased male patients, lower for the ALD carriers (BAEP, SEP and CNV were more frequently abnormal) and very low for the AMN carriers. Only the biochemical assays appeared to have any value for the characterization of female carriers of ALD and AMN.     

DM基因CTG重复数与BAEP、SEP、VEP对比分析

目的：探讨强直性肌营养不良（DM）患者及其家系成员三核苷酸重复数CTG（胞嘧啶、胸腺嘧啶、乌嘌呤）的变化与脑干听觉诱发电位（BAEP）、体感诱发电位（SEP）、视觉诱发电位（VEP）的关系。方法：用聚合酶链（PCR）扩增及DNA杂交法对5例临床诊断DM患者及其中三个家系的16名成员进行DM基因的CTG重复数和BAE、SEP和VEP测定。结果：10名正常人CTG重复数是30个，BAEP、SEP、VEP正常；5例DM病人CTG重复数均在85个以上，其中2列在1605个以上，明显高于正常人；16例家系成员中除4例正常，余12例CTG重复数均超过正常基因，而且，CTG重复数与临床症状、BAEP、SEP、VEP轻重有关。结论DM基因诊断有其临床症状、BAEP、SEP、VEP改变相一致。     

多系统萎缩44例的临床与神经电生理特点分析

目的 探讨临床和神经电生理检查对于多系统萎缩(MSA)的诊断价值。方法 对44例MSA患者分组分析其临床特点、肌电图(EMG)、神经传导速度(NCV)、躯体感觉诱发电位(SEP)、运动诱发电位(MEP)、脑干听觉诱发电位(BAEP)及视觉诱发电位(VEP)。并比较临床表现和电生理检查结果在各组间的差异。结果 本组患者以自主神经功能障碍和小脑生共济失调的异常率最高(88．6％)。帕金森综合征出现率在各组间差异有显著意义(P值分别为0．027、0．007、0．025)，卧立位血压异常在拟诊组和可能组间差异有显著意义(76．5％、18．2％)。EMG和NCV的异常率为38．1％，各组间出现率有不同。各种诱发电位的异常出现率在分组比较中无显著性差异。结论 仅凭临床表现无法对：MSA进行分组。各项神经电生理检查中以BAEP的阳性率最高。EMG和NCV结果在各组之间的差异提示该项检查对于MSA的分组可能有一定的帮助。     

Magnetic stimulation motor evoked potential in multiple sclerosis. Comparison with visual evoked potentials, brain stem auditory evoked potentials and somatosensory evoked potentials]

This study consists of 45 patients with clinically definite MS, laboratory supported definite MS and clinically probable MS. We compared MEP results with other multimodal evoked potentials (VEP, BAEP and SEP). The abnormal rate of MEP was 87.6%, which was the highest. Abnormal MEP showed prolonged central motor conduction time (CMCT), consistent with pathological change of the demyelination. There was a evident correlation between the abnormal MEP and VEP, which is consistent with the most common MS (Devic Syndrome) in our country.     

39例多系统萎缩的神经电生理特点分析

目的:观察多系统萎缩(MSA)患者神经电生理改变,探讨神经电生理对MSA的诊断价值。方法:22例行肢体骨骼肌肌电图(EMG)和神经传导速度(NCV)检测,39例均行肛门括约肌肌电图(EAS-EMG)检测,35例行脑干听觉诱发电位(BAEP)检测,26例行下肢体感诱发电位(SEP)检测,10例行视觉诱发电位(VEP)检测。电生理检查结果与本科检查室正常值比较。结果:肢体骨骼肌EMG和NCV的异常率为36．4％,肛门括约肌EMG异常率为89。7％,均呈神经源性受损表现;诱发电位的异常出现率分别为:BAEP(57．1％)、SEP(34．1％)、VEP(21．4％)。结论:神经电生理检测对于MSA的早期诊断有一定的帮助,可提高诊断的准确性。     

支架置入术对椎基底动脉系统短暂性脑缺血发作患者诱发电位的影响

目的 观察支架置入术能否改善椎基底动脉系统短暂性脑缺血发作（TIA）患者的亚临床症状。方法 11例症状性椎基底动脉狭窄的椎基底动脉系统TIA患者,支架置入术前后分别检测体感诱发电位（SEP）、脑干听觉诱发电位（BAEP）、视觉诱发电位（VEP）,记录各诱发电位的潜伏期及波幅。结果 （1）术前诱发电位均异常,主要表现为SEP N20及P40潜伏期异常,BAEPⅠ、Ⅲ、Ⅴ波潜伏期延长,VEP P100潜伏期延长。（2）与术前相比,术后1周BAEP表现为Ⅰ～Ⅲ波潜伏期缩短（P =0.046）、Ⅲ波幅升高（P =0.05）;SEP表现为N20潜伏期缩短（P =0.012）,N13～N20间期缩短（P =0.013）,P14～N20间期缩短（P =0.005）;VEP表现为 P100潜伏期缩短（P =0.022）。结论 支架置入术后,椎基底动脉系统TIA患者的SEP、BAEP、VEP好转,提示患者的亚临床症状恢复。     

Neurophysiologic and intellectual evaluation of beta-thalassemia patients

In order to detect involvement of the central and peripheral nervous system in beta-thalassemic patients, 32 children and young adults (mean age 14.5 +/- 6.4 years) participated in a systematic neurophysiologic and intellectual prospective study. All patients were in a regular transfusion program, receiving subcutaneous desferrioxamine chelation and maintaining a mean serum ferritin level of 2,101.56 +/- 986.32 ng/ml. Study patients underwent neurophysiologic evaluation consisting of brainstem auditory, visual and somatosensory evoked potential examination (BAEP, VEP, SEP) as well as motor and sensory nerve conduction velocity studies (MCV, SCV). Additionally, the verbal, performance and total IQ were assessed in patients under 16 years of age using the Weschler Intelligence Scale for Children (WISC-III). The incidence of abnormal BAEP, VEP, SEP and NCVs was 0, 3.12, 3.12 and 18.75%, respectively, findings comparative to or better than previously reported. On the contrary, the prevalence of abnormal total IQ score was considerably high (36.4%), not correlating, however, to any of the parameters assessed (age, sex, ferritin level, BAEP, VEP, SEP, NCV). Factors associated with chronic illness, rather than the disease per se, could play a potential role in the development of cognitive dysfunction in beta-thalassemia patients.     

Neurophysiologic assessment of mucopolysaccharidosis III.

OBJECTIVE: To describe finding of various neurophysiologic tests in patients with mucopolysaccharidosis III (MPS III) early in the disease course. METHODS: Patients were evaluated with flash visual evoked potentials (VEP), brainstem auditory evoked potentials (BAEP), electroencephalography (EEG), and nerve conduction studies (NCS) before they underwent hematopoietic stem cell transplantation (HSCT). RESULTS: Thirteen children underwent at least one neurophysiologic test before HSCT. The mean age at testing was 2.7 years. Ten of 11 (91%) patients had a normal flash VEP, and all 9 who had BAEP had normal central conduction. EEG was normal in 7/13 (54%), with the others showing diffuse slowing. NCS was normal in 10/11 (91%) patients. CONCLUSIONS: Despite extensive central nervous system involvement in MPS III, flash VEP and BAEP are almost always normal. EEG is often abnormal early in the disease. SIGNIFICANCE: This is the first report of neurophysiologic tests in a large series of MPS III patients.     

Evoked potentials and CSF-immunoglobulins in MS: relationship to disease duration, disability, and functional status

In 100 MS patients, BAEP and tibial SEP abnormality rates increased significantly with disease duration and clinical disability. VEP correlated non-linearly with disease duration, and median nerve SEP correlated with disability. In multifactorial analysis, however, BAEP correlated significantly only with clinical brainstem and cerebellar signs. These results suggest that evoked potentials correlate more strongly with neurological status of the functional subsystems than either overall disability or disease duration. These findings indirectly suggest that evoked potentials may be useful monitors during large therapeutical trials in MS patients.     

Evoked potential studies in Friedreich's ataxia and progressive early onset cerebellar ataxia

We recorded somatosensory evoked potentials (SEP) in 15 patients affected by Friedreich's ataxia (FA) and in 9 patients with progressive early onset cerebellar ataxia (PEOCA). Brainstem auditory evoked potentials (BAEP) were also recorded in 14 FA patients and in five PEOCA patients. SEP results showed clear differences between groups of FA, evidence of peripheral involvement was seen in all patients, with absence of the N9 potential or a major reduction of its amplitude. In patients in whom central responses could be recorded, conduction velocity was normal or near normal up to the brainstem but was reduced from brainstem to cerebral cortex. Four patients with PEOCA had SEP abnormalities similar to those seen in FA. In the five other patients, the amplitude and latency of N9 were normal but conduction velocity was reduced from brainstem to cerebral cortex. In FA, BAEP were abnormal in all patients with a disease duration of four years or more but were normal in four of the five PEOCA patients. Systematic evoked potential recording is useful in the investigation of hereditary ataxias.     

A case of alpha coma in acute brainstem dysfunction--consecutive electroencephalograms and evoked potentials

A 31-year-old woman was admitted because of severe headache and dysarthria in December 1985. Neurological examination on admission revealed severe impairment of consciousness, anisocoria, absent light reflex on the right side, and evidence of left hemiparesis, but other brainstem reflexes were intact. A CT scan taken shortly after arrival demonstrated a large hematoma in the right temporal lobe and the right cerebellum. Breathing became irregular and intubation was needed. An emergency operation was performed. After the operation the patient remained comatose without any spontaneous respiration or brainstem reflexes. The next day she was still comatose without any spontaneous movement and other neurological finding remained unchanged. An initial EEG obtained at this time showed an 8- to 9-Hz alpha rhythm of about 15-40 microV with preponderance over the posterior and central regions. Some spontaneous variability was noted. The same day, investigations of brainstem auditory evoked potential (BAEP), visual evoked potential (VEP), and somatosensory evoked potential (SEP) were performed. BAEP showed only the first, second and third waves (I-III) bilaterally. VEP was able to elicit the primary response (II-III) without the secondary response. SEP could not be obtained from the early cortical response to left median nerve stimulation, but showed N14 bilaterally and small N20 upon right median nerve stimulation. On the second day of hospitalization, a repeated EEG showed generalized slowing with loss of alpha frequency rhythms and it proved impossible for SEP to elicit N20 bilaterally. At this time, BAEP showed bilateral I-IIIth waves and VEP still showed primary response.(ABSTRACT TRUNCATED AT 250 WORDS)