Influence of magnetic resonance imaging on somatosensory and brain-stem auditory evoked potentials in man

Summary There is still a need to prove that even static magnetic fields up to 1.5 T used in magnetic resonance imaging (MRI) are biologically safe and harmless for humans. Recordings of median and ulnar nerves and brain-stem auditory evoked potentials in 20 patients were completed prior to and after MRI investigation of the central nervous system. Neither the somatosensory nor the auditory evoked potentials exhibited any significant change of latencies, interpeak latencies or amplitudes. Since these electrophysiological parameters are highly dependent on the quality of nerve conduction and integrity of information processing in various nuclei, it may be assumed that MRI causes no lasting changes in either respect.     

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     

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.     

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.     

脑干听觉诱发电位对癫(癎)患儿检测的意义

目的探讨脑干听觉诱发电位在癫患儿检测中的意义。方法对2000-01~2008-01我院38例癫患儿BAEP的检测结果进行总结。结果BAEP正常15例(39.5%),异常23例(60.5%),其中21例BAEP改变形式多样,异常指标相混出现。结论癫患者存在脑干功能异常。     

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.     

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.     

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     

Effects of carbamazepine and valproate on brainstem auditory evoked potentials in epileptic children

Brainstem auditory evoked potentials (BAEPs) were recorded in 18 epileptic children receiving carbamazepine and 10 epileptic children receiving valproate. BAEPs were recorded before the administration of antiepileptic drugs (AEDs) and 13 months later during which the children received AEDs. Statistical analysis of peak latencies and interpeak intervals of waves I–III–V were made. Carbamazepine treatment resulted in prolongation of peak latencies of waves I–III–V and interpeak intervals I–III and I–V. Valproate monotherapy, on the other hand, caused no consistent changes on BAEP. On the basis of these results we suggest that chronic carbamazepine therapy exerts a suppressive influence on the auditory pathways, both peripherally at the level of the cochlea and/or auditory nerve, and centrally at the brainstem.     

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.     

Acoustic tumour detection with early auditory evoked potentials and neuroradiological methods

Summary A total of 43 patients with surgically identified acoustic neuromas were tested. Results of early auditory evoked potentials (EAEP) and of neuroradiological methods were analysed. Abnormal EAEPs were observed in all patients. In 73% of the cases the EAEP indicated the retrocochlear site of the lesion; in 27%, however, the results did not localize the exact site of the lesion owing to a lack of waves I, II and III due to a pronounced hearing loss.Neuroradiological procedures provided an indication of the site and extent of the tumour. The number of true positives was 21 of 29 cases with polytomography of the petrous bone, 23 of 28 with computed tomography and in all cases when pontine angle cisternography and computed tomography combined with gas cisternography were performed.The EAEPs provide a screening-test for acoustic tumour detection at an early stage. Wave abnormalities indicative of a lesion at the acoustic nerve should lead to a neuroradiological investigation and are particularly valuable in cases with small intracanalicular tumours.

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Zusammenfassung 43 Patienten mit einem operativ gesicherten Akustikusneurinom (AN) wurden untersucht, wobei die Aussagekraft der frühen akustisch evozierten Potentiale (FAEP) und verschiedener neuroradiologischer Methoden überprüft wurde. Veränderte FAEPs wurden bei allen Patienten gefunden (100% richtig-positive Befunde). In 73% der Fälle erlaubten die FAEP eine Aussage über den retrocochleären Sitz der Schädigung; in 27% jedoch war eine topische Zuordnung nicht mehr möglich, da die topographisch wichtigen Wellen I-III wegen der Hörstörung nicht zur Darstellung gelangten.Die neuroradiologischen Methoden zeigten Sitz und Ausdehnung des Tumors an. Richtig-positive Befunde zeigten sich in 21 von 29 der Fälle bei der Felsenbeintomographie, in 23 von 28 bei der Computertomographie, in allen 19 Fällen bei der Cisternographie und bei allen 6 Patienten, bei denen eine CT in Verbindung mit einer Luftfüllung durchgeführt wurde.Die FAEP eignen sich als Sreening-Test, wobei sich der Tumor in einem frühen Stadium erfassen läßt. Treten Wellenveränderungen auf, die auf eine Schädigung am N. VIII hinweisen, ist eine weiterführende neuroradiologische Untersuchung indiziert. Die FAEP-Methode hat sich besonders bei kleinen noch intrakanalikulär gelegenen Tumoren bewährt.

     

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.

     

Asymmetry of long-latency auditory evoked potentials in LGI1-related autosomal dominant lateral temporal lobe epilepsy

PURPOSE: To investigate auditory processing with cortical long-latency auditory evoked potentials (AEPs) in patients with autosomal dominant lateral temporal lobe epilepsy (ADTLE). METHODS: Eight patients with LGI1-related ADTLE belonging to a family with predominantly aphasic seizures were studied. Sixty-five individuals without epilepsy served as controls. AEPs (N1-P2 amplitudes) to binaural tones were recorded over the left and the right hemispheres. Brainstem auditory evoked potentials (BAEPs) to monaural rarefaction clicks also were analyzed. Group differences were statistically assessed with Student's t test and repeated-measures analysis of variance. RESULTS: Left N1-P2 AEP amplitudes were moderately reduced in ADTLE patients (p = 0.005). No group differences in BAEP were found, indicating unaffected cochlear system and auditory brainstem pathways. CONCLUSIONS: A moderate, but highly significant reduction in N1-P2 AEP amplitudes over the left hemisphere was demonstrated in patients with ADTLE. This finding corresponds to the cardinal symptom of aphasia in this family, and also to the generally prevailing left-sided EEG abnormalities in this condition. The background for this electrophysiologic lateralization in LGI1-related epilepsy is unknown. It may be related to a specific function of LGI1 in the dominant hemisphere.     

Changes in visual evoked potentials in children on chronic dialysis treatment

Visual evoked potentials (VEP) were recorded in 20 children undergoing dialysis for chronic renal failure. VEP before treatment (72 h after last dialysis) were pathological in 17 patients (85%); responses obtained 3 h after treatment were abnormal in only 6 cases (30%). Furthermore, all patients improved after treatment, except two who were unchanged. However, VEP recorded immediately after dialysis were worse in 4 of 7 patients than before treatment, probably as an effect of the dysequilibrium syndrome; they improved spontaneously afterwards. The acute changes caused by dialysis seem to be more evident in children than in adults. No correlations have been found between blood chemistry indexes and VEP modifications. Finally, VEP have proved to be more sensitive than EEG in identifying a central nervous system (CNS) dysfunction in these uremic patients.     

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.

     

Brain-stem auditory evoked responses in diagnosis of central pontine myelinolysis

Summary Central pontine myelinolysis (CPM) developed in association with acute adrenocortical insufficiency during correction of severe hyponatraemia in a 58-year-old woman. Repeated CT scanning and NMR imaging were normal from the onset of the illness. Electroencephalography and brainstem auditory evoked responses showed abnormalities consistent with a brain-stem lesion, which resolved as the patient made a gradual but incomplete recovery. Our observations illustrate the value of electrophysiological monitoring in CPM and support the proposed association between this condition and the rapid correction of an electrolyte imbalance.     

脑干听觉诱发电位在听阈正常的语言发育迟缓患儿中的意义

目的 探讨脑干听觉诱发电位（BAEP）在听阈正常而语言发育迟缓患儿中的变化规律及应用价值.方法 分析100例听阈正常而语言发育迟缓患儿BAEP的变化规律;按年龄分组比较两个年龄段之间各波的延长时间.结果 （1）BAEP正常10例,异常90例,BAEP表现为Ⅰ、Ⅴ波潜伏期（PL）延长,Ⅲ~Ⅴ、Ⅰ~Ⅴ波峰间期（IPL）延长;（2）随着年龄增长,Ⅴ波PL与Ⅲ~Ⅴ波IPL延长时间越长.结论 Ⅰ波、Ⅴ波延长对早期诊断听阈正常而语言发育迟缓患儿具有一定的意义,说明即使听阈正常也可能存在听觉传导通路异常,且随着年龄增加,脑干上段受损越严重.     

Brainstem auditory evoked potentials in postconcussion syndrome

Brainstem auditory evoked potentials (BAEPs) were recorded from 55 patients with postconcussion syndrome (PCS) to elicit evidence of an organic and subclinical brainstem disorder. Fifteen patients (27.3%) showed abnormal responses unilaterally or bilaterally, especially for one or more interpeak latencies prolonged beyond the upper 99% confidence limits. Other 9 patients had borderline responses. The BAEP alterations were not correlated either with dizziness at the time of recording, or with vestibular troubles in the routine caloric test. Though BAEP abnormalities may be present a long time after injury, we found an improvement of responses in the majority of 14 re-tested patients. These data show that BAEP can give an objective demonstration of a reversible brainstem disorder in patients with PCS.

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Sommario I potenziali evocati acustici del tronco cerebrale (BAEP) sono stati registrati in 55 pazienti affetti da sindrome soggettiva postcraniotraumatica (PCS), per evidenziare un possibile danno organico subclinico del tronco cerebrale. Quindici pazienti (27.3%) hanno mostrato risposte alterate unilateralmente o bilateralmente, soprattutto a causa della presenza di una o più latenze interpicchi oltre i limiti fiduciali superiori del 99%. Altri 9 pazienti hanno mostrato risposte borderline. Non sono state ritrovate correlazioni tra il reperto di BAEP alterati e la presenza di vertigini all'atto dell'esame, né con il comportamento dell'esame vestibolare. Benché le alterazioni del BAEP si possano osservare anche a distanza di molti mesi dal trauma, la maggioranza dei pazienti con BA EP alterati, ad un secondo esame ha mostrato un miglioramento della risposta. Tali dati dimostrano che i BAEP sono in grado, in alcuni pazienti affetti da PCS, di evidenziare un danno organico del tronco cerebrale, passibile di regressione.

     

体温过高对豚鼠耳蜗电图-脑干听觉诱发电位综合波的影响

目的：探讨体温过高对耳蜗电图-脑干听觉诱发电位综合波(ECochG-BAEP SW)的影响。方法：计算机平均叠加技术记录豚鼠脑干听觉诱发电位(BAEP)、耳蜗电图(ECochG)和：ECochG—BAEP SW，体表物理升温法逐步升高豚鼠体温，观察3组电位波形、波峰潜伏期(PL)、波峰间潜伏期(IPL)和波幅的变化。结果：随体温升高(36℃至42℃)，ECochG-BA：EPSW波形始终兼具BAEP和ECochG的特点，有十分突出的1波，其波幅为BA：EP的I波波幅的数倍，且明显大于ECochG的N1波波幅；与BAEP和ECochG一致，ECochG-BAEPSW的PL和IPL随体温升高而逐渐缩短；与BAEP的Ⅰ，Ⅱ，Ⅲ波和ECochG的N1，N2，N3波波幅相似，ECochG-BAEP SW的1，2波波幅也在体温过高至40℃后开始出现显著降低。结论：体温过高对豚鼠ECochG-BAEPSW的影响与BAEP和ECochG相似，且其波形始终兼具两者特点。     

Early auditory evoked potentials (EAEP) in vertebral basilar insufficiency

Summary Stimulation with a short tone pip elicits an acoustic nerve compound action potential (I) and different waves (II–VII) in the initial 10 ms. Seven waves have been studied in 40 control subjects and five waves in 12 patients with vertebral-basilar insufficiency. Abnormalities of the different waves were observed at levels such as cochlea and/or acoustic nerve, medulla, caudal pons, rostral pons, and midbrain. The recording of early auditory evoked potentials (EAEP) is a noninvasive method of confirming impairment of the auditory pathway caused by a reduced vascular supply of vertebral and basilar arteries.