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.     

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.     

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.     

Short term neurophysiological monitoring in multiple sclerosis bouts. Evaluation of steroid treatment

Visual (VEP) and brainstem auditory (BAEP) evoked potentials (EP) were recorded in 21 multiple sclerosis (MS) patients in acute relapse before and after steroid treatment. VEPs were abnormal in 14/21 patients and BAEPs in 10/21 patients before treatment. In 4 patients with acute optic neuritis (ON), an improvement of VEPs paralleled clinical evolution in 3 cases. Substantial and contrasting changes in VEPs or BAEPs, with no clinical counterpart, were related to a spontaneous fluctuation of EPs in acute relapses of MS. These changes suggest frequent subclinical (multifocal and, possibly, sequential) central nervous system involvement in MS bouts. Group analysis showed nonsignificant changes in EP parameters before and after treatment. Our results indicate that evoked potentials (EPs) are of limited value for monitoring the short-term effect of steroid treatment in MS in bouts.

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Sommario I potenziali evocati visivi (VEP) ed acustici troncoencefalici (BAEP) sono stati eseguiti in 21 pazienti affentti da sclerosi multipla (SM) in fase di poussée, prima e dopo un ciclo di trattamento con steroidi. Prima del trattamento i VEP edi BAEP sono risultati alterati in 14 e 10 pazienti rispettivamente. 4 pazienti presentavano una neurite ottica (ON) in fase acuta; in 3, dopo il trattamento, è stato rilevato un significativo miglioramento dei VEP e dell'acuità visiva. Significative, ma contrastanti, modificazioni dei VEP e BAEP, riscontrate in altri 5 pazienti, non correlate all'evoluzione clinica, sono suggestive di un interessamento subclinico, multifocale e possibilmente sequenziale, durante una poussée della SM. L'analisi per gruppi non evidenzia differenze statistiche significative tra prima e dopo il trattamento. I nostri risultati indicano che i potenziali evocati sono di limitata utilità ai fini di un monitoraggio a breve termine della SM in poussée.

     

Subclinical VEP abnormalities in patients on chronic deferoxamine therapy: longitudinal studies

As deferoxamine (DFO) appeared to have certain toxic effects on the sensory pathways in some of our patients on nightly subcutaneous deferoxamine (DFO) for transfusion-dependent anemia, treatment was stopped in all of these patients to obtain a comprehensive baseline assessment of sensory function. Visual evoked potentials (VEPs) were studied in all patients; the 77 described in this report all had normal ophthalmological examinations. Abnormally prolonged VEP latencies were found in 21%. The patients remained off DFO for 2-6 months, and most of those with abnormal VEPs who were retested showed improvement in their VEPs over this period with the VEPs returning to within normal range in half the cases; two showed no change. Since restarting DFO, VEP latencies in 10 of these patients have increased again beyond normal limits, as have the VEPs in 7 who had previously normal VEPs. Although most of the 77 patients have VEPs that are currently normal and stable while on DFO, a significant sub-group have abnormal VEPs that appear sensitive to the administration of DFO and may reflect a vulnerability to DFO neurotoxicity. These data suggest that the VEPs can detect subclinical toxic effects of DFO on the visual system and should be considered as a monitor for patients receiving chronic DFO therapy.     

Electrophysiological findings in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a common, autosomal dominant neurocutaneous disorder in which any organ system, including the skin, skeleton and nervous system can be affected. In this study, we compared the electrophysiological and magnetic resonance imaging (MRI) findings in patients with NF1. Thirty-nine adolescent and adult patients (23 women and 16 men) diagnosed with NF1 with a mean age of 25.8±10 years (10-56) were included in this study. We collected data in the form of the results of neurological examinations, multimodal evoked potentials (EPs; brainstem auditory evoked potentials, BAEPs; somatosensory evoked potentials, SEPs; and visual evoked potentials, VEPs), cerebral/orbital/spinal MRIs, and electroneuromyography (ENMG). Twenty (51.3%) patients showed abnormal VEPs, 14 (35.9%) showed abnormal SEPs, and six (15.4%) showed abnormal BAEPs. All evoked potentials were abnormal in four (10.3%) cases. These electrophysiological findings occurred primarily in the absence of any clinical sign related to the affected system. MRI revealed pathologic findings in 26 of 39 patients, and these were not always correlated with visual, auditory, or somatosensory pathway abnormalities. ENMG showed polyneuropathy in two of 33 patients who underwent ENMG. Our study showed that MRI and electrophysiological abnormalities may be found in most patients with NF1, even in the absence of associated clinical symptoms or signs. Electrophysiological testing is helpful for monitoring the subclinical involvement of the central and peripheral nervous systems in patients with NF1.     

Evoked potentials in motor system diseases

We studied pattern-shift visual (PSVEP), brainstem auditory (BAEP), and somatosensory (SEP) evoked potentials in 38 unselected patients with motor system diseases (MSD) (28 sporadic, 10 familial). PSVEPs were normal in all patients, and BAEPs were normal in all except one with clinical hearing loss who had absent waves I and III and prolonged wave V latencies. Median and tibial SEPs revealed definite CNS conduction abnormalities in only 1 of 30 and 1 of 18 patients, respectively. In addition, four patients had peripheral and four had peripheral or central delays on tibial nerve testing. There were no or only small group differences in central conduction SEP, BAEP, and PSVEP values in patients with normal studies compared with controls. This study suggests that central conduction SEP, BAEP, or PSVEP abnormalities can rarely be attributed to MSD and that their presence in patients suspected of having this disorder should prompt a search for an alternative diagnosis.     

Brain-stem auditory evoked potentials in children with brain-stem or cerebellar dysfunction

Brain-stem auditory evoked potentials (BAEPs) were recorded in 23 children who had signs of brain-stem or cerebellar dysfunction. In patients with brain-stem gliomas, BAEPs were abnormal in all except one, in whom involvement of the brain-stem auditory pathway was limited to the midbrain tectum. The BAEPs were normal in neuronal ceroid lipofuscinosis, but abnormal bilaterally in inheritable leukoencephalopathies. All patients with Leigh's encephalopathy had BAEP abnormalities; in two, abnormalities occurred before the appearance of lesions on computed tomographic scan. Patients with Friedreich's ataxia and giant axonal dystrophy had abnormal BAEPs, but the test was normal in a child with similar neurologic findings with vitamin E deficiency. Patients with diffuse metabolic encephalopathies had variable findings. Thus, BAEP abnormalities are nonspecific for various disease processes but are frequently seen in neoplastic and neurodegenerative diseases, with primary white matter or extensive brain-stem involvement.     

Brain stem auditory and visual evoked potentials in multiple sclerosis

The diagnostic value of the checkerboard pattern-reversal visual evoked potential (VEP) and the random, low rate stimulated brain stem auditory evoked potential (BAEP) was compared in 99 patients with established or suspected multiple sclerosis (MS). In normal subjects examined by both techniques no abnormal recordings were found. In 49 patients with definite MS an incidence of abnormality was found in 100% of VEP and in 84% of BAEP recordings. In 50 patients with probable or possible MS an abnormal VEP was found in 70% and an abnormal BAEP in 50%. When the two examinations were combined, the diagnostic yield increased to 100 and 80%, respectively. 22 patients had only spinal symptoms; in these the VEP gave 73%, the BAEP 55% and the combination 82% abnormalities. The combination of the two techniques was found useful for demonstrating demyelinating lesions in the central nervous system, the diagnostic value being greatest when these lesions were clinically silent.     

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.     

Multimodal evoked potentials in myotonic dystrophy (MyD).

By means of multimodal evoked potentials (EPs), we evaluated the central nervous system (CNS) involvement in 25 subjects suffering from myotonic dystrophy: brainstem auditory evoked potentials (BAEPs), middle-latency auditory evoked potentials (MLAEPs) and somatosensory evoked potentials (SEPs) from the upper limb were performed on all subjects, whereas only the 19 patients, whose clinical ocular abnormalities were slight, underwent pattern-electretinograms (PERGs) and pattern visual-evoked potentials (VEPs) in order to identify the site of lesion among visual pathways (retinal and/or retroretinal). PERGs were abnormal in 8/19 subjects, VEPs in 8/19 subjects (the two techniques were simultaneously abnormal in 8 eyes), BAEPs in 7/25 subjects, MLAEPs in 4/25 subjects (in one subject both BAEps and MLAEPs were abnormal) and SEPs were abnormal in 1/25 subjects. 13/25 of our subjects showed at least one EP that revealed a CNS involvement. The electrophysiological alterations were not correlated either with subject age or with disease duration. Multimodal EPs enabled us to demonstrate that CNS involvement in myotonic dystrophy is important and mainly affects the visual and auditory system.     

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.     

The acute deafness of definite multiple sclerosis: BAEP patterns

Of 705 patients with or suspected of multiple sclerosis who underwent evoked potential recording during a 5 year period, 12 patients with definite multiple sclerosis experienced an acute hearing loss during a relapse of the demyelinating disease. Hearing loss was unilateral in all of the 12 cases but one; tinnitus was associated with hearing loss in 9 of the 12 patients. Deafness is an unfrequent symptom in the course of multiple sclerosis, being estimated to be no more than 3% in large series of multiple sclerosis. Brain-stem auditory evoked potentials were recorded in all 12 patients, during the relapse with acute hearing loss in 4 of them, after the relapse with hearing loss in the 8 others. During the relapse with hearing loss, BAEP abnormalities were present ipsilateral to the hearing loss in all 4 patients, wave I being absent in 2 of them. BAEPs were drastically improved when recorded after the relapse with hearing loss in 2 of the 3 patients in whom repeated records were made. BAEPs were abnormal on the side of the previous hearing loss in 5 out of the 8 patients recorded after the relapse with hearing loss. Clinical and BAEP data suggest that, in accordance with the anatomical organization of the auditory pathways, the lesion causing unilateral hearing loss in multiple sclerosis could be situated in the cochlear nerve or close to its entry zone in the brain-stem. However, dissociation between unilateral hearing loss and a normal peak I and I-III interval may occur.     

Cranial nerve function in workers exposed to polychlorinated dioxins and furans

OBJECTIVE: To look for possible effects of polychlorinated dioxins and furans (PCDD/F) on cranial nerve function. MATERIAL AND METHODS: Clinical and neurophysiological examinations [visual and brainstem auditory evoked potentials (VEP and BAEP), blink reflex] in 121 PCDD/F exposed workers of one pesticide producing plant. RESULTS: BAEP abnormalities were more frequent in workers with chloracne (6 of 33 workers, 18.2%) than in those without chloracne (7 of 84, 8.3%), but this was not statistically significant (chi2: 2.33). VEP abnormalities were seen in one worker with and two without chloracne. Clinically visual functions were normal except in one worker, who was amaurotic since birth. Blink reflex abnormalities without corresponding clinical findings were observed in two patients without chloracne. CONCLUSION: Severe exposure to PCDD/F is not followed by clinical signs of cranial nerve dysfunction but may create an increased risk for abnormal BAEP findings, which were more than twice as common in workers with chloracne. Although this difference did not reach statistical significance, it cannot exclude a toxic effect of PCDD/F, as statistical significance is difficult to achieve with such small numbers of workers. In none of the workers, BAEP abnormalities were accompanied by clinical signs of hearing dysfunction.     

Evoked potentials and EEG in multiple sclerosis

Thirteen patients with clinically definite multiple sclerosis (MS) were studied with electroencephalogram (EEG), magnetic resonance imaging (MRI), evoked potentials and cerebrospinal fluid (CSF) analysis. We attempted to correlate the findings with physical disability as defined by Kurtzke score and presence of dementia or seizures. More severe plaque disease on MRI and increased physical disability correlated significantly with abnormality on brain-stem auditory evoked potentials (BAEPs) while visual evoked potential (VEP) abnormality correlated only with MRI findings. No such correlation was found with the EEG. The close relationship between BAEP and MRI abnormalities probably reflects frequent involvement of brain-stem corticospinal pathways.     

Does testing of brainstem auditory response aid diagnosis in progressive spastic paraparesis?

40 patients with progressive spastic paraparesis of uncertain cause were studied in order to assess the outcome of their investigations. Abnormalities of the visual evoked response (VER) were found in 33%, indicating a second lesion in the nervous system. An additional 15% had abnormalities of the brainstem auditory evoked potentials (BAEP), indicating an supra-spinal, though not necessarily a second lesion. Qualitative CSF examinations for oligoclonal IgG banding showed abnormality in 30%, and considerable overlap (83%) with the patients who had abnormal VER, but not in those with an abnormal BAEP alone. It is concluded that the BAEP is of value when the VER and CSF are normal.     

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.     

Effects of age on event-related potentials in chronic alcoholics: a multimodal study.

To test different versions of the premature aging hypothesis in alcoholics, brainstem auditory evoked potentials (BAEPs), long-latency auditory evoked potentials (LAEPs), P3 and visual evoked potentials (VEPs) were recorded in 32 alcoholic subjects. The phenomena in patients' event-related potentials (ERPs) differ from those observed in normal aging subjects and become more pronounced with age. ANOVA showed a significant effect by group (alcoholic patients/controls) on certain parameters of BAEPs (III, III-V, I-V), VEPs (P100 latency) and LAEPs (N1-P2 amplitude and N2 latency) unaffected by age, while age had a significant effect on some parameters of LAEPs (N2-P3 amplitude, P3 latency) unaffected, or less affected by chronic alcohol consumption. At a clinical level, abnormalities in BAEPs and VEPs seem good early trouble indices in alcoholic patients, while alterations in latencies and amplitudes of LAEPs appear in older patients. These data seem to be in favor of a critical age or critical abuse in the action of alcohol, in place of the classical hypothesis of premature aging.     

Brainstem auditory evoked potentials in patients with mitochondrial encephalomyopathy.

Brainstem auditory evoked potentials (BAEPs) were evaluated in three patients with mitochondrial encephalomyopathy belonging to the same family. This study showed marked alterations of BAEPs in all patients: reduction of wave amplitude, poor repeatability of responses in test-retest and abnormalities in wave form and latency. The neuroradiological examinations (CT-scan, MRI) did not show significant structural brain abnormalities. Abnormal BAEPs in our patients may be related to central metabolic disorder rather than hearing loss.