Evoked potentials in multiple system atrophy (MSA)

OBJECTIVES: To study the involvement of pyramidal tracts and sensory pathways in multiple system atrophy (MSA). MATERIALS AND METHODS: Evoked potential studies were performed in 45 MSA patients suffering from either MSA of cerebellar type (MSA-C) or MSA of parkinsonian type (MSA-P). RESULTS: Motor evoked potentials were normal in all MSA patients, whereas visual and somatosensory evoked potential abnormalities were found in about 40% of the MSA patients with no significant difference between the cerebellar (MSA-C) and parkinsonian (MSA-P) subgroup. Abnormal latencies of wave III in brainstem auditory evoked potentials were significantly more frequent in MSA-C. CONCLUSIONS: Abnormalities of somatosensory, visual and auditory evoked potentials are frequent findings in MSA, whereas abnormal motor evoked potentials are not a characteristic feature of the disease.     

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.     

Middle latency auditory evoked potentials (MLAEPs) in (MS)

Middle latency auditory evoked potentials (MLAEPs) were studied in 30 definite multiple sclerosis (MS) patients in addition to brain-stem auditory evoked potentials (BAEPs). BAEP abnormalities were detected in 18 (60%) patients. MLAEPs were abnormal in 22 (73%) of them. In 15 patients BAEPs and MLAEPs were both abnormal. MLAEPs were found abnormal in 7 of the 12 patients with normal BAEPs. In 18 patients with abnormal BAEPs only 3 had normal MLAEPs. MLAEPs abnormalities are consistent with a rostral auditory pathway involvement. Therefore, they can be used in combination with BAEPs to examine the whole auditory system to improve the sensitivity.     

Brainstem auditory evoked potentials in the diagnosis of multiple sclerosis

Brainstem auditory evoked potentials (BAEPs) have been investigated in 34 patients affected by Multiple Sclerosis. Abnormalities were found in 68% of the patients. Silent lesions of the brainstem were detected in 60% of the clinically definite and in 44% of the probable cases. The diagnostic value of these findings is discussed.

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Sommario I potenziali evocati uditivi sono stati investigati in 34 pazienti affetti da sclerosi multipla. Anormalità sono state evidenziate nel 68% dei pazienti affetti da sclerosi multipla clinicamente definita. Lesioni silenti del brainstem sono state trovate nel 60% delle forme clinicamente definite e nel 44% di quelle probabili. Il valore diagnostico di questi reperti è discusso.

     

多发性硬化的诱发电位特点

目的分析多发性硬化(multiple sclerosis,MS)模式翻转视觉诱发电位(pattern reversal evoked po-tential,PRVEP)、脑干听觉诱发电位(brainstem auditory evoked potential,BAEP)和体感诱发电位(somatosenso-ry evoked potential,SEP)等三种诱发电位(evoked potential,EP)的临床特点。方法对83例确诊MS患者进行回顾性分析,根据有无相应临床症状、病程及功能残障程度对EP进行分层研究,探讨其变化规律。结果三种EP的异常率在有临床症状组〔PRVEP、BAEP及下肢短潜伏期体感诱发电位(SLSEP)异常率分别为88.00%、66.67%、100%〕与无临床症状组(PRVEP、BAEP及下肢SLSEP异常率分别为60.61%、31.71%、79.63%)间比较均存在统计学差异(均P<0.05)。PRVEP的峰潜伏期(PL)延长及侧间峰潜伏期差值(ILD)增加的异常率之和与病程呈正相关(r=1.0,P<0.05);病程在20年以内时BAEP异常率与病程呈正相关(r=1.0,P<0.05);SLSEP下肢未引出率与病程呈正相关(r=1.0,P<0.05)。PRVEP异常率与EDSS分值呈正相关(r=1.7,P<0.01);SLSEP上肢异常率及下肢未引出率也与EDSS分值呈正相关(分别r=1.8,P<0.01;r=1.6,P<0.01)。结论三种EP的异常率与有无相应临床症状相关,且与病程及功能残障程度在一定范围内呈正相关。     

Usefulness of trigeminal somatosensory evoked potentials to detect subclinical trigeminal impairment in multiple sclerosis patients

Trigeminal somatosensory evoked potentials (TSEPs) by surface electric pulse stimulation were recorded in 30 normal subjects and in 70 multiple sclerosis (MS) patients, 13 of whom presenting clinical trigeminal impairment. We observed significant prolongation of all TSEPs parameters in MS group. TSEPs were abnormal in 45 patients (64.3%). Clinical and neurophysiological data agreed in 36 patients (51%) on 84 sides (60%). TSEPs were able to detect clinically silent lesions 54 times. TSEPs recording proves to be an additional useful test in MS multimodal evoked potential protocols.     

Multimodal evoked potentials in spinocerebellar ataxia types 1, 2, and 3

Aims:

Spinocerebellar ataxias (SCA) are a clinically heterogeneous group of disorders that are characterized by ataxia and an autosomal dominant pattern of inheritance. The aim of our study was to describe the findings of evoked potentials (EPs) among genetically proven SCA types 1, 2, and 3 and to additionally evaluate if EPs can be used to differentiate between them.

Materials and Methods:

Forty-three cases of genetically proven SCA (SCA1 = 19, SCA2 = 13, and SCA3 = 11) were evaluated with median somatosensory-EP (mSSEP), visual-EP (VEP), and brainstem auditory-evoked response (BAER) by standard procedures and compared with normative laboratory data. An EP was considered abnormal if latency was prolonged (>mean + 3 standard deviation (SD) of laboratory control data) or the waveform was absent or poorly defined. The waves studied were as follows: mSSEP - N20, VEP - P100 and BAER - interpeak latency 1-3 and 3-5.

Results:

EPs were abnormal in at least one modality in 90.9% of patients. The most common abnormality was of BAER (86.1%) followed by VEP (34.9%) and mSSEP (30.2%). The degree of abnormality in VEP, mSSEP, and BAER among patients with SCA1 was 42.1, 41.2, and 73.3%, respectively; among patients with SCA2 was 38.5, 27.3, and 100%, respectively; and among patients with SCA3 was 18.2, 37.5, and 88.9%, respectively. The differences between the subgroups of SCAs were not statistically significant.

Conclusions:

BAER was the most frequent abnormality in SCA types 1, 2, and 3; abnormalities of mSSEP were comparable in the three SCAs; whereas, abnormality of VEP was less often noted in SCA3.     

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.     

The location by early auditory evoked potentials (EAEP) of acoustic nerve and brainstem demyelination in multiple sclerosis (MS)

Summary Tone pips of suprathreshold intensities elicit an acoustic nerve response (I) and six low amplitude brainstem potentials (II–VII) during the initial 10 ms. Seven waves were studied in 40 control subjects and 5 waves (I–V) in 47 patients with MS. The results suggest involvement of the auditory pathway of 24 of 27 patients in the clinically definite, of 5 of 9 cases in the probable and in none of 5 patients in the possible MS groups. EAEPs were normal in 6 cases with a spinal form with one exception where changes of potential were indicative of a midbrain lesion. Dysfunction within the acoustic pathway was observed at the level of the acoustic nerve and in the medulla oblongata, pons and midbrain. The significance of the bilateral EAEP abnormalities found in some patients at different levels is discussed with regard to a polytopic location of the underlying lesion.This work includes part of a thesis of E. Schäfer (University of Mainz)     

MRI and visual-evoked potentials in partners of multiple sclerosis patients

Hawkes CH, Chawda S, Derakshani S, Muhammed N, Visentin E, Boniface D. MRI and visual‐evoked potentials in partners of multiple sclerosis patients.
Acta Neurol Scand: 2012: 125: 424–430.
© 2011 John Wiley & Sons A/S. Objective – Some epidemiological evidence, particularly concerning the role of Epstein Barr Virus implies that multiple sclerosis (MS) may be transmissible and if correct, this might be revealed by increased prevalence of MS in cohabiting partners. Methods – We addressed this problem by neurological assessment, visual‐evoked potentials (VEP) and magnetic resonance imaging (MRI) in 112 partners of patients with MS in comparison to a control group of 93 individuals with clinically non‐significant head or neck pain and in comparison to UK prevalence. Results – We found one instance of conjugal definite MS. Including this case, VEP were abnormal in five instances with either significant delay (n = 3) or increased interocular latency difference (IOLD) (n = 2) in partners of MS patients thus raising the possibility of subclinical optic nerve demyelination. The mean absolute value of IOLD in partners was greater than the value in controls (P = 0.033). There were no significant differences in MRI findings between the two groups. Conclusion – The finding of one conjugal pair and abnormal VEP in a further four MS partners could have several explanations. It is compatible with the concept of a transmissible agent, although our observations could be due to several biases as well as the play of chance alone.     

Brainstem auditory evoked potentials in tuberous sclerosis

Brainstem auditory evoked potentials were recorded in 4 subjects and pattern reversal evoked potentials in 1 subject, all with tuberous sclerosis. Alterations were found (absence or delay of components and prolonged interpeak intervals) which may suggest impaired nervous conduction also at brainstem level in patients with tuberous sclerosis.

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Sommario Sono stati registrati i potenziali evocati auditivi troncoencefalici in 4 soggetti con sclerosi tuberosa, in uno di essi sono stati registrati anche i potenziali evocati visivi da pattern reversal. Sono state ritrovate alterazioni delle risposte (assenza o ritardo di alcune componenti ed intervalli interpicco prolungati) che possono suggerire l'esistenza di una conduzione nervosa alterata anche a livello del tronco dell'encefalo nei pazienti con sclerosi tuberosa.

     

Visual and auditory evoked potentials in the early diagnosis and follow-up of neurosarcoidosis

Visual and brainstem auditory evoked potentials (VEPs, BAEPs) were recorded in 23 patients with neurosarcoidosis. Eight patients (35%) had abnormal BAEPs, and 10 (43%) had abnormal VEPs. Four of the 8 patients with abnormal BAEPs had facial paresis, one had impaired memory and only 3 had symptoms and signs compatible with brainstem lesion. Seven of the patients with abnormal VEPs had no visual symptoms. These findings suggest that BAEP and VEP can reveal subclinical nervous system involvement in sarcoidosis and can also help in the early diagnosis of neurosarcoidosis. Successive recordings of 5 patients showed that BAEP and VEP were useful in the follow-up of these patients.     

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.     

Evaluation of various brain structures in multiple sclerosis with multimodality evoked potentials,blink reflex and nystagmography

Summary Pattern reversal visual evoked potentials (VEP), blink reflexes, auditory brainstem evoked potentials (ABEP), spinal and scalp recorded somatosensory evoked potentials (SSEP), and nystagmographic records were investigated in 55 patients with multiple sclerosis (MS), who were separated in different categories of probability according to the clinical history, symptoms, and signs. The combined use of different electrophysiological methods forms a sensitive battery for investigating clinically uncertain cases of MS. It was stressed that care should be taken in the interpretation of the electrophysiological findings, since a single lesion in the central nervous system, particularly in the brainstem, may affect different functional systems simultaneously and therefore mimic a disseminated disease.

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Zusammenfassung Visuelle musterevozierte Potentiale, der elektrisch ausgelöste Blinkreflex, auditorisch evozierte Hirnstammpotentiale, somatosensorisch evozierte Potentiale mit Ableitung über dem unteren Cervicalmark und dem jeweiligen kontralateralen Handfeld sowie nystagmographische Ableitungen wurden bei 55 Patienten mit einer Multiplen Sklerose untersucht. Die Patienten wurden entsprechend der anamnestischen Daten und der klinischen Symptomatologie in vier Gruppen unterschiedlicher diagnostischer Wahrscheinlichkeit getrennt. Die Resultate zeigten, daß die Kombination verschiedener evozierter Potentiale einen hohen Aussagewert in solchen Fällen haben kann, in denen die Diagnose einer MS klinisch nicht eindeutig ist. Es wird jedoch hervorgehoben, daß die Interpretation der elektrophysiologischen Befunde mit großer Sorgfalt vorgenommen werden soll, da eine einzige Läsion im Zentralnervensystem, besonders im Bereich des Hirnstammes, gleichzeitig verschiedene funktionelle Systeme befallen und dadurch eine disseminierte Erkrankung vortäuschen kann.

     

Detection of brainstem lesions in multiple sclerosis: comparison of brainstem auditory evoked potentials with nuclear magnetic resonance imaging

Topographical information provided by brainstem auditory evoked potentials (BAEPs) was investigated in 43 patients by comparison with cerebral nuclear magnetic resonance imaging (NMR). Lesions in the region of the brainstem auditory pathways were demonstrated by BAEPs in 44.2%, and in 39.5% by NMR. As regards brainstem levels, in 15/21 (71.4%) with abnormal findings at least one lesion was verified by NMR-matched BAEP results. The study confirms the topographical information provided by the BAEPs on the different levels of the brainstem, but not the assumption that generation of the BAEPs is predominantly ipsilateral. BAEPs retain their importance for the detection of disseminated lesions in the diagnosis of multiple sclerosis (MS) in the era of expensive imaging methods.     

帕金森病早期多种诱发电位检测的临床诊断价值

目的 观察帕金森病早期体感诱发电位(SL-SEP)、脑干听觉诱发电位(BAEP)和视觉诱发电位(PR-VEP)的异常特征．寻找敏感可靠的诊断指标。方法 对一组52例Yahr分期为Ⅰ期的帕金森病人和一组40例年龄匹配的健康对照组进行三种诱发电位观测。结果帕金森病早期SLSEP异常率为69．2％；BAEP的异常率为32．7％：PR-VEP的异常率为30、7％，病例组SL-SEP各主波峰潜伏期、峰间潜伏期、P25和N30波幅与对照组比较差异有湿著性意义；病例组BAEPⅠ—ⅢIPL、Ⅲ—ⅤIPL、Ⅰ一Ⅲ／Ⅲ一Ⅴ比值和PR-VEP的P100PL与对照组比较差异无显著性意义．结论 在帕金森病的早期，皮层感觉处理过程已受到干扰：体感诱发电位中央前成份以及顶成份P25是一个敏感的诊断指标。     

Somatosensory and visual evoked potentials in children with cerebral palsy: Correlations and discrepancies with MRI findings and clinical picture

Purpose: To determine if there is any association between the findings of visual evoked potentials (VEPs), somatosensory evoked potentials (SEPs), and magnetic resonance imaging (MRI) findings with the neurodevelopment and severity in children with cerebral palsy (CP). Methods: The present study included 15 children with spastic diplegic CP and five children with spastic hemiplegic CP and 42 healthy children as controls. The number of the controls was two-times greater than the study group to increase statistical power of this study. VEPs and SEPs were recorded in the CP children and compared with healthy controls. All MR scans were obtained using a 1.5 T MR scanner. Results: A significant difference was found in the latencies P100 (VEP) between the CP and controls. No correlations between increased P100 latencies and asphyxia, prematurity, the CP severity, MRI findings and mental retardation were noted. A significant difference in N13–N20 conductions (SEPs) between the subjects with CP and the control group was found. SEPs were positively correlated with mental retardation in CP children. The brain lesions in MRI showed a significant correlation with the CP severity scores and mental retardation. Conclusion: The differences in VEPs and SEPs were determined between CP children and healthy children. The MRI findings were positively correlated with the CP severity and mental retardation.     

Serial evoked potentials in multiple sclerosis bouts. Relation to steroid treatment

Serial recordings of multimodal sensory (visual, acoustic and somatosensory) evoked potentials were made in 19 relapsing-remitting Multiple Sclerosis patients enrolled in a clinical trial designed to evaluate the efficacy of dexamethasone versus high-and low-dose methylprednisolone in acute multiple sclerosis bouts. Electrophysiological and clinical evaluations were performed at the onset of therapy and until 6 months after the end of treatment. Using an arbitrary Evoked Potentials score that takes into account both latency and waveform alterations, we found a positive correlation between evoked potentials and clinical disability scores. Furthermore, different electrophysiological profiles were detected in the three therapeutic subgroups. Evoked potentials may be useful for monitoring acute Multiple Sclerosis bouts and evaluating the effect of therapy.

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Sommario I potenziali evocati visivi, acustici e somatosensoriali sono stati monitorati in 19 pazienti affetti da Sclerosi Multipla, inclusi in un trial clinico volto alla valutazione dell' efficacia del desametazone e di basse e alte dosi di metilprednisolone nel trattamento delle riaccensioni della malattia. La valutazione clinica ed elettrofisiologica veniva effttuata all'inizio e alla fine del trattamento (a 15 giorni) e a 3 e 6 mesi dopo la sospensione. Utilizzando una scala arbitraria elettrofisiologica che prendeva in considerazione sia le alterazioni di latenza che di morfologia, abbiamo riscontrato una correlazione positiva tra punteggio elettrofisiologico e disabilità clinica. Inoltre differenti profili elettrofisiologici erano osservati nei tre sottogruppi terapeutici. Lo studio dei potenziali evocati appare utile nel monitoraggio delle riaccensioni della malattia e nella valutazione dell' effetto della terapia.

     

诱发电位监测在显微外科手术治疗颅内动脉瘤中的初步应用

背景 近年来显微外科手术技巧取得很大的进步,然而颅内动脉瘤手术仍然存在众多并发症.多种术中特定手术操作造成的大脑功能区缺血与术后神经系统功能损伤有关.为进一步提高颅内动脉瘤手术的安全性、减少术后脑缺血性并发症的发生,有必要在术中对相应脑血管供血区域的缺血性损伤进行实时的监测.我们在颅内动脉瘤显微外科手术中联合应用运动诱发电位(MEPs)、体感诱发电位(SSEPs)及脑干听觉诱发电位(BAEPs)监测,提高术中诱发电位(EPs)信号改变对特定手术步骤导致脑缺血的敏感性,并研究它们与术后神经功能结果之间的关联性.方法 我们于2006年3月至2006年8月对我院25例采用显微手术的动脉瘤患者联合应用MEPs、SSEPs和BAEPs进行术中监测.对22例前循环动脉瘤手术,单纯行SSEPs监测4例,行MEPs及SSEPs监测18例,对3例后循环动脉瘤手术同时监测MEPs、SSEPs及BAEPs,将术中监测结果与术后神经功能作前瞻性观察研究.①SSEPs监测记录及刺激电极均采用皮下针电极.监测上肢SSEPs时,按国际脑电学会制定(10～20)系统,参考电极放在Fz,记录电极放在C3'、C4'和双侧Erb点,分别记录双侧皮质电位和外周电位.刺激电极放在腕部左右正中神经,刺激强度为15～25 mA,刺激间期0.2 ms,刺激频率3.1 Hz,波带通50～300 Hz,分析时间50 ms.监测下肢SSEPs时,记录电极置于Cz和双侧腘窝,分别记录双侧皮质电位和腘窝电位.刺激电极放在内踝部左右胫后神经,刺激强度为20～30 mA,记录参数与上肢SSEPs监测相同.术中主要观察手术侧皮质电位(上肢为N20波,下肢为P37波).所有波形均以麻醉后40 min SSEPs的值为标准,警报标准为波幅降低大于基线的50%或潜伏期延长10%.②MEPs监测采用外接电刺激器(Digitimer D 185 stimulator),刺激电极采用螺旋塞电极,记录电极采用皮下针电极.刺激电极放在C3/C4或C1/C2前1～2 cm,阴极放在对侧相应的地方.刺激采用恒流经颅连续短串电刺激5个单相方波,阳极刺激,持续时间300μs,刺激间隔2 ms(重复频率500 Hz),最大刺激电压600 V.记录从双侧肱二头肌、拇短展肌、胫前肌和拇展肌诱发的肌源性MEPs.警报标准为肌原性MEPs波幅消失.采用四联刺激肌肉收缩试验(TOF)监测神经肌肉反应活动.③BAEPs监测记录电极采用皮下针电极,置于两侧乳突.参考电极置于头顶(Cz).耳道插入式短声刺激.11.1 Hz疏密波,100 dBnHL级,对侧耳道60 dBnHL白噪音掩蔽.波带通30～1 500 Hz,分析时间15 ms,叠加1 000次.警报标准为V波潜伏期延长大于0.8 ms或波幅降低大于基线的50%.麻醉维持采用异丙芬、芬太尼、异氟醚、N2O和万可松,控制吸入性麻醉剂和肌松药的用量.结果 对载瘤动脉临时阻断、载瘤及临近重要血管的误夹、过度脑牵拉、血管痉挛或小穿支血管损害等术中事件引起的脑缺血,MEPs5/21、SSEPs5/25、BAEPs1/3出现异常.3例术后出现新的肢体运动功能障碍病人中,术中均有MEPs异常,而SSEPs仅1例异常.术中EPs未出现异常的病例,术后均未出现新的神经功能障碍.结论 通过本组初步研究,笔者认为MEPs监测对于运动系统缺血性损伤的敏感性优于SSEPs监测,术中EPs信号改变与术后神经功能结果之间具有良好的关联性,而稳定的EPs联合监测有助于预测健全的感觉运动功能,并且保证足够的远端侧支血流量,允许术者安全地完成潜在危险性的操作.