Brainstem auditory evoked potential abnormalities in myelomeningocoele in the older child.

Brainstem auditory evoked potentials and clinical findings were examined in 18 children over the age of 5 years who were born with myelomeningocoele which was closed at birth, and whose hydrocephalus was managed by long term shunting in most of them. The potentials were compared with age and sex matched normal subjects and with four patients with hydrocephalus only. All but one had an abnormal brainstem auditory evoked potential with 72% showing a delay in the II-V and I-V interpeak latencies of more than three standard deviations. It is proposed that the abnormalities are a reflection of brainstem dysgenesis which is part of an associated Arnold-Chiari malformation, though the malformation was clinically asymptomatic in all. The usefulness of the brainstem auditory evoked potential for assessing the course of hydrocephalus and for predicting symptomatic Arnold-Chiari malformation is questioned.     

Brainstem auditory evoked potential (BAEP) abnormalities in brucellosis

Twelve patients with neurobrucellosis and 17 patients with systemic brucellosis without neurological involvement underwent a brainstem auditory evoked potentials (BAEP) study. All neurobrucellosis patients (100%) showed abnormalities in their BAEP recordings, suggestive of brainstem lesions at various levels. On the other hand, only 5 (29%) of the 17 patients with systemic brucellosis had mild unilateral BAEP abnormalities, while the remaining 12 had normal responses. Comparison of pooled data between the systemic brucellosis and neurobrucellosis groups showed highly significant differences in all BAEP parameters. The recording of BAEP is thus considered a sensitive supplementary method to reveal CNS lesions in patients with neurobrucellosis.     

Brainstem auditory evoked potential study in children with autistic disorder

Brainstem auditory evoked potentials were compared in 109 children with infantile autism, 38 with autistic condition, 19 with mental retardation, and 20 normal children. Children with infantile autism or autistic condition had significantly longer brainstem transmission time than normal (p<.001). Autistic features, rather than age, sex, or lower mentality, correlated with brainstem transmission time (p<.0001). The autistic characteristics may be related to dysfunction of the brainstem which affects the processing of the sensory input through the auditory pathway. The brainstem lesion may be part of a generalized process of neurological damage that accounts for the deviant language, cognitive, and social development in the spectrum of autistic disorder.We thank R. Ko and F. Pun for their scretarial assistance.     

Brainstem auditory evoked response in adrenoleukodystrophy

Clinical, laboratory, and electrophysiological data, including brainstem auditory evoked responses, are reported in a case of adrenoleukodystrophy. A striking asymmetry was noted in wave VI of the brainstem auditory evoked potential, followed by absence of any recognizable wave on the abnormal side. The presumed site of origin of wave VI is the medial geniculate body, a structure severely involved in adrenoleukodystrophy. It is suggested that the brainstem auditory evoked response may promise noninvasive diagnostic aid in this disorder and that absence of wave VI may emerge as a clinically useful finding in diseases of the central nervous system.     

Brainstem auditory evoked responses in leukodystrophies

Brainstem auditory evoked responses (BAERs) were recorded in seven patients with Pelizaeus-Merzbacher leukodystrophy (PMD), two with adrenoleukodystrophy (ALD), and one with metachromatic leukodystrophy (MLD). BAERs were altered in all patients, and the alterations were severe in 9 of the 10 patients. A patient with ALD who as yet had no neurologic symptoms showed only minimal abnormality of the BAERs, consisting of prolongation of the latency of wave V. In the remaining nine patients, only wave I generated in the extramedullary portion of the eighth nerve was recorded with or without a wave II. Subsequent components (III through VII) were absent. No abnormality of BAERs was observed in the 10 known carriers of PMD. The combination of BAERs and EEG is helpful in differentiating leukodystrophy from progressive gray matter diseases.     

Brainstem auditory evoked potentials in meningomyelocele

The brainstem auditory evoked potentials (BAEP) of twenty-seven Myelomeningocele (MMC) patients were analyzed and compared with the results of a normal population. The longest wave V or V-I interpeak latencies were seen in patients with shunted hydrocephalus and cranial nerve defects. The shortest wave V and V-I interpeak latencies were found in patients without hydrocephalus. However, these latencies of MMC patients were significantly longer than the latencies of a normal population. Wave I latencies of all MMC subgroups were not significantly different from the results of the normal probands. It is assumed that V-I interpeak latency prolongation in MMC patients, which is related to the severity of the clinical signs of the Arnold Chiari malformation, is mostly due to an elongation of the brainstem.     

Brainstem auditory evoked potential abnormalities in vascular malformations of the posterior fossa

Recent reports indicate that malformations of arteries and veins in the posterior fossa are a common cause of facial spasm and trigeminal neuralgia. More rarely they may also cause facial nerve paresis and hearing loss. When vascular malformations are present, brainstem auditory evoked potentials (BAEPs) sometimes show abnormalities similar to those usually recorded in patients with tumours in the cerebellopontine angle. In three patients with facial spasm, one with trigeminal neuralgia and one with facial paresis pathologically delayed absolute latencies and/or interpeak latencies of BAEPs associated with vascular malformations were found. It is concluded that those BAEP abnormalities associated with tumours in the posterior fossa may also be caused by vascular malformations. BAEPs are valuable aids to the diagnosis of such malformations.     

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.

     

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.

     

Brainstem auditory evoked responses in Lafora disease

Brainstem auditory-evoked responses (BAERs) have been studied in five patients suffering from Lafora-type of progressive myoclonus epilepsy proven by skin biopsy and in ten healthy volunteers. At the time of examination the patients were not taking benzodiazepines and showed myoclonic jerks. In all patients the central conduction time (interpeak latencies I-V, I-III, III-V) and the amplitude (amplitude ratio I/V) of BAERs were within the +/- 2 S.D. limits of the normal values. Since Lafora disease is a neuropathologically prevalent grey-matter illness (typical inclusion bodies are stored intraneuronally) these data indicate that diseases primarily affecting the brainstem grey-matter are usually associated with normal BAERs.     

Brainstem auditory evoked responses in brainstem infarction

Brainstem auditory evoked responses (BAERs) were recorded in 40 patients with clinically definite brainstem infarction, and results were compared to localizations from physical signs and CT scans. The BAER was abnormal in 92% of patients with evidence on physical examination of dysfunction of lateral structures in the pons or midbrain. Normal BAERs were seen with medially-situated or medullary lesions. When both rostrocaudal level and lateralization were considered, the BAER indicated damage in additional areas not evident on physical examination in 25% of patients. However, physical signs indicated damage in areas not reflected by the BAER in 22% of patients. Therefore, the BAER complements the localization obtained from physical findings. BAERs were abnormal in more of these patients than were CT scans, and thus are useful for confirmation of bedside impressions.     

Brainstem auditory evoked potentials in Wilson's disease

Twelve patients with Wilson's disease, aged 11-25 years, underwent brainstem auditory evoked potential (BAEP) study. The results were correlated to clinical, neuroradiological and laboratory data. Ten had prominent to severe neurological manifestations, suggestive of involvement of one or several CNS structures, and 2 were neurologically free. All had evidence of abnormal copper metabolism, and 8 had CT scan evidence of brain atrophy, or hypodense areas in basal ganglia, or both. The 2 patients without neurological manifestations as well as one with neurological signs had normal BAEP. One patient with neurological signs had increased N1 latency due to cochlear hearing loss, but normal interpeak intervals, while 8 of 10 patients with prominent neurological symptoms and signs had abnormal BAEPs (prolongation of NIII-NV interpeak interval). The value of NIII-NV interpeak interval correlated with the number of different neurological signs (neurological score) attributable to involvement of different CNS structures (r = 0.64 at P = 0.001). Abnormal BAEPs do not seem to be an early finding in Wilson's disease.     

Brainstem auditory evoked potentials in Chiari-II malformation

Brainstem function in patients with Chiari-II malformation was evaluated by brainstem auditory-evoked potentials (BAEPs). All cases had associated hydrocephalus, some of which were shunted. The effect of the shunting operation on the wave forms was examined as well as the age-wave relationships. Although the shunting operation resulted in shortened brainstem conduction time, the overall postshunt responses were still far from normal. Another significant finding was that whereas there were remarkable abnormalities in recorded wave-forms in cases younger than 8 years, normal or almost normal responses were obtained in all cases older than 8. BAEP abnormalities could not be correlated with the severity of meningomyelocele, nor was the predictive value of response in assessing potential risk of symptomatic Chiari malformation established.This paper was presented at the 15th Annual Meeting of the International Society for Pediatric Neurosurgery, New York, July 12–16, 1987     

Brainstem auditory evoked potentials and middle latency auditory evoked potentials in young children

Measurements of brainstem auditory evoked potentials (BAEP) and middle latency auditory evoked potentials (MLAEP) are readily available neurophysiologic assessments. The generators for BAEP are believed to involve the structures of cochlear nerve, cochlear nucleus, superior olive complex, dorsal and rostral pons, and lateral lemniscus. The generators for MLAEP are assumed to be located in the subcortical area and auditory cortex. BAEP are commonly used in evaluating children with autistic and hearing disorders. However, measurement of MLAEP is rarely performed in young children. To explore the feasibility of this procedure in young children, we retrospectively reviewed our neurophysiology databank and charts for a 3-year period to identify subjects who had both BAEP and MLAEP performed. Subjects with known or identifiable central nervous system abnormalities from the history, neurologic examination and neuroimaging studies were excluded. This cohort of 93 children up to 3 years of age was divided into 10 groups based on the age at testing (upper limits of: 1 week; 1, 2, 4, 6, 8, 10 and 12 months; 2 years; and 3 years of age). Evolution of peak latency, interpeak latency and amplitude of waveforms in BAEP and MLAEP were demonstrated. We concluded that measurement of BAEP and MLAEP is feasible in children, as early as the first few months of life. The combination of both MLAEP and BAEP may increase the diagnostic sensitivity of neurophysiologic assessment of the integrity or functional status of both the peripheral (acoustic nerve) and the central (brainstem, subcortical and cortical) auditory conduction systems in young children with developmental speech and language disorders.     

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.     

Brainstem auditory evoked potential (BAEP) abnormalities in subjects with craniovertebral malformations

We report the data on 42 monaural BAEP recordings from 10 patients with craniovertebral malformations. Of 8 preoperative recordings from 3 patients 6 showed an increased I–III interpeak latency (IPL). Of 28 recordings taken shortly (1–12 months) after surgery 21 showed an abnormal I–III IPL. On the other hand, of 6 recordings from 3 patients 20 years after surgery 5 were in the normal range and 1 showed an abnormal I–III IPL. Although the most important site of craniovertebral malformations is the cervicomedullary junction, the results reported suggest unilateral or asymmetrical bilateral involvement of the medullary-pontine junction, on the evidence of BAEP wave III, in a large proportion of patients with these malformations.

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Sommario Riportiamo i dati relativi a 42 BAEPs monoaurali registrati in 10 pazienti con malformazioni della cerniera craniovertebrale. 6 BAEPs, su 8 registrati prima dell'intervento decompressivo, hanno mostrato un incremento in latenza dell'interpicco I–III. 21 BAEPs, su 28 registrati a breve distanza dall'intervento (da 1 a 12 mesi dopo), hanno fatto rilevare anormalità dell'interpicco I–III. Al contrario, su 6 BAEPs ottenuti in 3 pazienti 20 anni dopo l'intervento, 5 sono risultati normali mentre una risposta monoaurale ha evidenziato anormalità dell'interpicco I–III. Anche se il livello princiaple di lesione, nelle malformazioni della cerniera, è la giunzione cervico-bulbare i nostri risultati depongono per un coinvolgimento monolaterale o bilaterale ma asimmetrico della giunzione bulbo-pontina, in un'alta percentuale di soggetti affetti da tale patologia.