Magnetic resonance imaging and brain-stem auditory evoked potentials in neuro-Behcet's disease

We studied central nervous system lesions in patients with neuro-Behcet's disease using magnetic resonance imaging (MRI) of the brain and recording of brain-stem auditory evoked potentials (BAEPs). MRI revealed abnormal findings in seven of eight patients. MRI studies demonstrated extensive regions with high intensity signal in the brain stem and/or basal ganglia on T2-weighted images obtained during the acute stage of the disease in three patients. One of these patients had a strongly gadolinum-enhanced round lesion in the lower pons. In four of the other five patients with chronic disease, brain-stem atrophy was observed on T1-weighted images. Atrophic changes were more severe in the brain stem than in the cerebellum. Abnormal BAEPs were observed in three patients and consisted of prolongation of interpeak latency of waves III-V and defects of wave III or V. Abnormal BAEPs were recorded in patients with severe inflammatory changes or progression of atrophic changes in the brain stem. Our findings show that MRI and BAEPs are useful in detecting the presence and assessing the degree of neurological involvement in patients with neuro-Behcet's disease.     

Brain function in patients with cerebral fat embolism evaluated using somatosensory and brain-stem auditory evoked potentials

Summary In two victims of traffic accidents with broken bones and fat embolism, serial recordings of somatosensory evoked potentials (SEPs) and brain-stem auditory evoked potentials (BAEPs) were examined to assess brain function. Initial SEPs and BAEPs revealed normal subcortical components, while the late cortical components of SEPs were abolished, findings indicative of diffuse dysfunction of grey rather than of white matter. As the neurological functions became normal, the late components appeared. It is concluded that while absent late components of SEPs do reflect cortical dysfunction, they are not necessarily associated with a poor prognosis. Repetitive recordings of SEPs appear to be a useful tool for assessing the neurological condition and the prognosis of patients with cerebral fat embolism.     

Visual and auditory evoked potentials during long-term vigabatrin treatment in children and adolescents with epilepsy.

OBJECTIVES: The aim of the study was to estimate the effects of Vigabatrin (VGB) as add-on therapy on visual (VEP) and brain-stem (BAEP) evoked potentials. METHOD: The investigation covered 100 epileptic patients from 8 to 18 years of age. The treatment included therapy with carbamazepine (CBZ) or valproate acid (VPA) using slow release formulations of these AEDs. Combination therapy was administered using add-on VGB in the recommended dose 57.4+/-26.5 mg/kg body mass/day. VEP and BAEP evoked potentials were recorded by means of Multiliner (Toennies, Germany). The obtained values were compared with age matched control group. RESULTS: Compared to control groups, significant differences in epileptic groups emerged in latencies of the peak III, V along with the interpeak intervals I-III of BAEP. Also VEP studies showed the reduction of N75/P100 and P100/N145 amplitudes. CONCLUSIONS: Adding VGB did not significantly increase the percentage of pathological abnormalities observed from EPs. Our electrophysiological studies demonstrate abnormalities in EPs parameters due to subclinical toxicity induced by AEDs. Major alterations produced bitherapy of VPA-SR + VGB and minor SR formulations of CBZ or VPA.     

多发性硬化患者头颅磁共振、诱发电位和IgG指数的对比研究

报道43例多发性硬化(MS)患者头颅磁共振成像(MRI)、诱发电位(EP)和IgG指数(IgGIndex)的对比研究结果。发现MRI的检测异常率为81.4％,而VEP仅53.7％、BAEP47.5％、IgGIndex57.5％。MRI在显示空间脱髓鞘方面是最敏感的方法,但VEP、BAEP只要有一项异常即判断为EP异常则其异常率高达79.5％,接近MRI。作者认为三者同时检查可以提高诊断的准确性。     

Brain-stem involvement in multiple sclerosis: a comparison between brain-stem auditory evoked potentials and the acoustic stapedius reflex

Summary Brain-stem auditory evoked potentials (BAEPs) and the acoustic stapedius reflex (ASR) were recorded in 68 patients with definite, probable and possible multiple sclerosis (using the definitions of McAlpine). The high incidence of abnormal results, 68% and 60%, respectively, pointed to the diagnostic value of these two measures in detecting brain-stem dysfunction. Combination of the methods increased the diagnostic yield to 85%. Since in part the same brain-stem generator sites underlie BAEPs and the ASR, it was considered that a study of their correlation might serve to increase the reliability and validity of these techniques. There was 71% agreement overall between results from the two measures. Furthermore, 72% of the joint BAEP and ASR abnormalities corresponded in detection of the brain-stem lesion site. It was concluded that the combined approach may supply powerful, complementary information on brain-stem dysfunction, which may aid in establishing the diagnosis of multiple sclerosis.This study was supported by the M. Sackler Foundation for Multiple Sclerosis Research     

Abnormalities of somatosensory and motor evoked potentials in adrenomyeloneuropathy: Comparison with magnetic resonance imaging and clinical findings

We studied 6 patients with adrenomyeloneuropathy (AMN) showing mild signs of central nervous system involvement. All patients underwent brain and spinal magnetic resonance imaging (MRI) and somatosensory (SEP) and motor (MEP) evoked potential study. Whereas SEPs and MEPs were abnormal in all patients, only 1 patient showed brain MRI abnormalities; spinal MRI showed hypotrophy without focal abnormalities in 4 of 6 patients. Median nerve SEPs, which were recorded with noncephalic reference montage, revealed delayed or absent scalp P14 far-field potential in all patients and abnormal spinal N13 in 2. Moreover, tibial nerve SEPs revealed abnormalities of the subcortical P30 response in all 4 patients in whom scalp-to-ear recording was employed. These findings strongly suggest that in the early stages of disease neurological dysfunction is localized in the spinal cord, where it is difficult to assess using MRI. However, SEPs and MEPs, which show a typical pattern of abnormality in these patients, could be useful in disclosing signs of long tract involvement and in monitoring treatment. © 1997 John Wiley & Sons, Inc. Muscle Nerve 20: 1249–1257, 1997     

Brain-stem auditory evoked potentials and blink reflex in friedreich's ataxia

Summary The brain-stem involvement in Friedreich's ataxia (FA) was studied by using brain-stem auditory evoked potentials (BAEPs) and the blink reflex. Ten out of 18 patients had abnormal BAEPs, the main abnormality being complete absence of responses and disappearance of wave V. Combined degeneration of the peripheral and central acoustic pathways probably accounts for these findings. The blink reflex was abnormal in 50% of the cases. The outstanding abnormality was bilateral delay of late responses with normal early response, which could be correlated with the known pallor of the descending trigeminal tracts. In contrast with BAEP findings, blink reflex abnormalities did not correlate with either the age of patients or the severity and duration of the disease. These data suggest a difference in susceptibility to degeneration between the auditory system and neuronal system subserving the blink reflex. We conclude that systematic BAEP and blink reflex recording is useful in the electrophysiological evaluation of FA patients.     

The effects of a supratentorial mass lesion on brain-stem auditory evoked potentials and short latency somatosensory evoked potentials

Nineteen patients with unilateral supratentorial mass lesion and without any evident clinical signs of transtentorial herniation were studied with Computed Tomography (CT), brain-stem evoked potentials (BAEPs) and central conduction time (CCT) of short latency somatosensory evoked potentials (SEPs). Sixteen had tumours, two had intracranial haematoma and one had chronic subdural haematoma. CT detected the initial signs of transtentorial herniation in every case. Preoperative I-V interpeak latency (IPL) was significantly (M+2SD) prolonged in 26% of cases on the lesion side and in 21% of cases on the opposite side. The mean I-V IPL was significantly prolonged both on the lesion side and the opposite side (P < 0.01, P < 0.02, respectively). Suppression of Wave V (M-2SD) was seen only in two cases, however, the mean amplitude of Wave V was significantly decreased both on the lesion side and on the opposite side (P < 0.001, P < 0.01, respectively). CCT of SEPs was significantly (M+2SD) prolonged in 33% of cases on the lesion side and in only 13% on the opposite side. The mean CCT was, however, significantly prolonged both on the lesion and on the opposite side (P < 0.001, P < 0.02, respectively). Postoperative I-V IPL was significantly prolonged in only 11% of cases while the mean I-V IPL was still significantly prolonged (P < 0.07) and the mean amplitude of Wave V was still suppressed (P < 0.001) on the lesion side. On the other hand, there was neither abnormality of I-V IPL nor suppression of Wave V on the opposite side. Postoperative CCT was significantly prolonged in 43% of cases and the mean CCT was also significantly (P < 0.01) prolonged on the lesion side. However, there was no prolongation of CCT on the opposite side. Preoperative findings of both BAEPs and SEPs show the abnormality due to the supratentorial lesion and postoperative findings of these potentials indicate both the effects of surgical decompression and the residual abnormalities due to the supratentorial mass lesion.     

酒精所致精神障碍患者的脑干听觉诱发电位

目的分析酒精所致精神障碍患者的脑干听觉诱发电位（ＢＡＥＰ）表现。方法对３０例长期嗜酒所致精神障碍患者进行ＢＡＥＰ检测，并与正常人进行对照。结果病例组ＢＡＥＰ各波峰潜伏期（ＰＬ）、峰间期（ＩＰＬ）延长，波形分化差，与正常对照组有显著性差异。结论ＢＡＥＰ异常与临床表现及影像学，实验室结果基本一致，提示诱发电位可作为慢性酒精中毒的诊断方法之一     

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.     

听觉诱发电位及体感诱发电位在颅脑外伤致昏迷患者的应用

严重颅脑损伤昏迷患者脑功能的监测是判断预后和指导治疗的重要手段。听觉诱发电位(BAEP)及体感诱发电位(SSEP)因其方便、无创并能连续实时监测昏迷患者相关神经传导通路电生理的变化,间接反映脑干上行激活系统、大脑皮层结构与功能的完整性,越来越成为临床对严重颅脑损伤昏迷患者预测预后和指导治疗的重要手段。本文就近年来相关研究进行综述,旨在指导临床实践。     

Hirayama disease: three cases assessed by F wave, somatosensory and motor evoked potentials and magnetic resonance imaging not supporting flexion myelopathy

Traumatic chronic injury of the cervical spinal cord caused by neck flexion (“flexion myelopathy”) is one of the suggested pathogenetic mechanisms for Hirayama disease (HD). Neurophysiological data, especially reporting particularly N13 cervical somatosensory response, are scarce and conflicting in HD. F wave, somatosensory evoked potentials (SEP), motor evoked potentials (MEP) and magnetic resonance imaging (MRI) studies were assessed in 3 HD male patients (aged 22, 36, and 51 years) with the aim of evaluating the functional effects of neck flexion in HD. Median and ulnar F waves, median, ulnar and posterior tibial SEP, and upper and lower limb MEP were performed bilaterally in standard conditions and during neck flexion in the patients. Cervical spinal MRI study was performed in standard position in two patients and both in standard and flexed positions in the third patient. F wave, SEP, and MEP findings did not show statistically significant differences in standard conditions and during neck flexion both in HD patients and controls. MRI with neck in standard position was normal in two patients, while in the third patient revealed cervical anterior horns signal changes and cord atrophy. In this patient, MRI with the neck in flexion showed that the spinal cord was normally located, was not compressed within the cervical canal and that there were no abnormalities of the dural sac. These findings suggest that in a complex disorder like HD no definite conclusions can be drawn from the present paper and some cases of HD without evidence of “flexion myelopathy” might have a different pathogenetic mechanism.

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Sommario  La mielopatia cervicale indotta dalla flessione traumatica del collo è uno dei meccanismi patogenetici ipotizzato per la malattia di Hirayama (MH). In questa malattia i dati neurofisiologici sono scarsi e contraddittori. Lo studio della onda F, dei potenziali evocati somatosensoriali (PES) e motori (PEM) e della risonanza magnetica (RM) spinale cervicale erano valutati in 3 pazienti (rispettivamente di 22, 36, e 51 anni di età) maschi affetti da MH con lo scopo di valutare gli effetti funzionali della flessione del collo nella MH. Lo studio neurofisiologico (onda F, PES e PEM) era attuato bilateralmente con collo in posizione standard ed in flessione. Lo studio della RM spinale cervicale veniva attuato in due pazienti con collo in posizione standard e nel terzo paziente con collo in posizione standard ed in flessione. I risultati degli studi neurofisiologici non mostrano differenze statisticamente significative con collo in posizione standard ed in flessione nei pazienti con MH e nel gruppo di controllo. La RM eseguita con collo in posizione standard era normale in due pazienti, mentre rivelava alterazioni del segnale a livello delle corna anteriori e atrofia del midollo a livello cervicale nel terzo paziente. In questo paziente, la RM attuata con il collo in flessione mostrava il midollo cervicale normalmente localizzato e non compresso nel canale spinale ed il sacco durale senza anormalità. In conclusione, nei nostri pazienti la flessione del collo non mostra significativi cambiamenti dello studio neurofisiologico (onda F, PES e PEM). Questi dati propongono che in un disordine complesso come la MH nessuna definitiva conclusione può essere tratta dall’ attuale lavoro e che alcuni casi di MH senza elettrofisiologiche ed neuroradiologiche evidenze di mielopatia cervicale possono avere un differente meccanismo patogenetico.

     

Preserved cortical somatosensory evoked potentials in apnoeic coma with loss of brain-stem reflexes: case report

A comatose patient suffering from diffuse cerebellar haemorrhage developed apnoea and brainstem areflexia, i.e. the clincial signs of brain death. However, median nerve somatosensory evoked potential testing 2.5 h and 22 h after the onset of this clinical syndrome showed cortical potentials partly preserved; these were abolished 46 h after the beginning of the clinical signs of brain death. This case report underlines the need for electrophysiological confirmation of brain death in patients with primarily infratentorial lesions.     

Diazepam improves recording of lumbar and neck somatosensory evoked potentials

To determine whether the decrease in muscle artifact provided by diazepam is of sufficient clinical value to justify its use, somatosensory evoked potentials recorded in examinations of 73 consecutive patients were compared with those recorded from 33 subsequent patients who were given 10 mg of diazepam orally just before the examination. With diazepam pretreatment there was clear improvement in the quality of lumbar and neck recordings--increased reproducibility and definition and ease of measurement--and also greater tolerance of the procedure and a slight shortening of time required for the test.     

Monitoring of somatosensory evoked potentials during carotid endarterectomy

Summary Somatosensory evoked potentials (SEPs) were monitored in the course of 368 carotid endarterectomies (CEAs) carried out in 312 patients. In an initial group of 26 patients the shunt was used routinely while in a second group, involving 342 CEAs, it was applied selectively on the basis of modifications which the SEP underwent during clamping. The criterion for shunting was the progressive reduction, up to 50%, of the N20-P25 amplitude. New postoperative neurological deficits appeared in 6 patients, all of whom displayed a transitory SEP flattening. The SEPs of 2 of these returned to normal by the time they awoke and both showed a clinical deficit homolateral to the operated side. In only 2 cases did the deficit fail to regress completely and their postoperative CT scans revealed ischaemic lesions. A positive relationship emerged between SEP changes and back pressure values; nonetheless, as many as 75% of the patients with low residual back pressure values (< 25 mm Hg) tolerated the clamping. SEP monitoring appears to provide a reliable basis for selectively applying a shunt when there is a high risk of haemodynamic ischaemia during clamping.     

运动诱发电位联合体感诱发电位监测在脊髓髓内肿瘤手术中的应用

目的 探讨全静脉麻醉下运动诱发电位(MEP)联合体感诱发电位(SEP)术中监测应用于脊髓髓内肿瘤手术的优越性、可靠性及临床应用价值.方法 对72例脊髓髓内肿瘤患者术中行SEP和MEP联合监测,参照McCormick评分标准对术前、术后脊髓功能的改变和诱发电位变化之间的关系进行统计分析.结果 14例脊髓神经功能改善,18例术后脊髓神经功能下降者与诱发电位监测结果具有一致性(P＜0.05).结论 对脊髓髓内肿瘤手术进行SEP与MEP监测有利于避免"假阴性/假阳性"结果及术后神经功能障碍的发生.     

Clinical correlates of abnormal brain-stem auditory evoked responses in multiple sclerosis

Brain-stem auditory evoked responses (BAERs) were examined in 178 patients with multiple sclerosis (MS) and compared to the frequency of abnormalities in visually evoked responses (VERs) and in CSF electrophoresis. In clinically definite MS, BAERs were abnormal in 61% and a significant relationship was noted between disability due to MS and the frequency and severity of BAER abnormalities. In suspected MS, BAERs showed evidence of a second lesion in 14% whereas VERs indicated a second lesion in 24%. Abnormal BAERs in patients with suspected MS with brain-stem signs were significantly associated with the presence of truncal and limb ataxia. In progressive possible MS, abnormal BAERs were found in 49% but indicated a second lesion in 35% of patients and were significantly related to the duration of illness. In progressive possible MS, abnormal VERs but not abnormal BAERs, were significantly associated with the presence of CSF oligoclonal IgG banding. Normal BAERs in association with clinical brain-stem abnormalities were found in 24% of patients with clinically definite MS, 50% with suspected MS and 33% with progressive possible MS.     

Changes in auditory P300 event-related potentials and brainstem evoked potentials in diabetes mellitus

To investigate the influence of diabetes mellitus on higher cognitive functions electrophysiologically, we studied auditory P300 event-related potentials (P300) in 40 NIDDM patients, taking into account wave I-V latencies (I-V) in auditory brainstem evoked potentials, clinical parameters and head MRI findings. Compared with 20 controls, diabetics had significantly longer P300 and I-V latencies. P300 latencies in diabetics correlated with neither I-V. HbA₁, blood glucose levels, nor disease duration. Of the 13 diabetics investigated neuroradiologically, four had lacunar infarcts with prolonged electrophysiological values. The remaining nine had normal MRI scans, but their physiological parameters were still significantly longer than those of controls. These findings suggest that NIDDM can independently alter higher cognitive and the central auditory pathway functions. Our data also suggest that these alterations occur regardless of the recent metabolic derangement and disease duration. Cerebrovascular ischemia, if present, also appears to contribute in part to cognitive alterations.     

多发性硬化患者前庭诱发肌源性电位的临床意义

目的研究多发性硬化(multiple sclerosis,MS)患者前庭诱发肌源性电位(vestibularevoked myogenic potentials,VEMPs)各参量的变化及临床意义,比较VEMPs与核磁共振、脑干听觉诱发电位对MS病变的检测能力。方法采用双耳短声刺激记录37例MS患者(有脑干症状21例、无脑干症状16例)和20名健康对照的VEMPs的潜伏期和振幅值,计算双侧在13ms左右出现的正波(p13)波幅潜伏期差值(Δp13)和振幅比(SR)。37例MS患者均做核磁共振成像,其中33例记录脑干听觉诱发电位。结果有脑干症状组和对照组相比,p13潜伏期显著延长[左侧为(13.84±2.57)ms和(12.20±1.10)ms,P<0.05;右侧为(14.69±2.96)ms和(12.10±2.60)ms,P<0.01],Δp13显著增大(1.63±1.82和1.00±1.44,P<0.01),而无脑干症状组差异无统计学意义。两组MS患者的p13-n23(在23ms左右出现的负波)振幅值与对照组相比均降低[左侧分别为(149.98±52.2)、(175.51±49.22)、(272.80±165.81)μV;右侧分别为(156.88±97.04)、(167.74±57.32)、(257.50±138.49)μV,P均<0.05],扩展的残疾功能量表评分与振幅有相关性(左侧r=0.45,右侧r=0.46,P均<0.05)。VEMPs与核磁共振相比,对病灶的检出率低(分别为33%与100%,P<0.05),与脑干听觉诱发电位相比差异无统计学意义。结论p13潜伏期及Δp13可作为判定MS前庭脊髓通路脱髓鞘的参考指标。VEMPs作为辅助诊断MS的一项新的诱发电位,对脑干病灶的诊断有一定临床参考意义。     

Some comments on the clinical use of evoked potentials

Summary In this survey we describe the uses of somatosensory, visual, and auditory evoked potentials (EPs), adding some critical comments on the values and pitfalls of these methods. It must be stressed that the application of EPs is most valuable when combined with a thorough neurological examination. There is general agreement that EP measurement is one of the best techniques for objective, noninvasive study of brain function in humans.