Brain stem auditory evoked potentials and chronic alcoholism

Brain-stem auditory evoked potentials (BAEPs) were obtained from 25 chronic alcoholic patients. The patients had been drinking heavily for an average of 15 years and a minimum of 5 years. All patients were totally abstinent for a minimum of 3 weeks. The morphology of waves were often altered. All presented prolonged I-III, III-V, inter-peak latencies (IPLs) and a loss of amplitude of wave V. The I-III, III-V and I-VIPLs were increased between 30 and 40 years, and III-V and I-VIPLs between 40 and 50 years. The incidence of abnormal BAEPs in patients with alcoholic epilepsy was not different from that of patients without a history of alcoholic seizures. Patients with clinical manifestations of alcoholic polyneuropathy had the highest incidence of abnormal BAEPs. BAEPs are more reliable in chronic alcoholic patients than EEG. The mechanisms of the increase in neural transmission time within the auditory brain-stem are discussed.     

Evaluation of ipsilateral and contralateral brainstem auditory evoked potentials in multiple sclerosis patients

Brainstem auditory evoked potentials (BAEP) were recorded simultaneously between the vertex and the mastoid ipsilateral and contralateral to the ear stimulated in 30 patients with multiple sclerosis (MS) and compared with the responses in a control group of 30 normal hearing adults. The control group showed that significant latency differences exist between ipsilateral and contralateral recording. Definitions of abnormalities were based on interwave separation and the wave V amplitude ratio. No case was found among the MS patients with an abnormal contralateral but normal ipsilateral response.     

Brain stem auditory evoked potentials: reduction of evaluation errors

The commonly used method of BAER evaluation is measuring the latency to the extreme points of the components. Because of the influence of noise it is sometimes impossible to determine precisely the true top of the peak. It is possible to avoid this defect by estimating the latency to the middle of the peak front. In this research S.D.s for both methods of evaluation were calculated for all interpeak intervals. According to the obtained data the use of the middle of the front of the peak for the latency evaluation gave 24% reduction in S.D.s.     

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.     

Right uninostril yoga breathing influences ipsilateral components of middle latency auditory evoked potentials

Abstract A previous report described selective electrical activity of the cerebral hemispheres with uninostril breathing. In the present study, middle latency auditory evoked potentials (MLAEPs) were recorded from symmetrical scalp sites during the practice of uninostril yoga breathing. There were two sessions (40 min each) of right nostril yoga breathing (RNB) and of breath awareness (BAW), with (i) before, (ii) test (either RNB or BAW) and (iii) after periods. The participants were 14 male volunteers aged between 18 and 33 years, and the setting was a yoga centre. MLAEPs were recorded from symmetrical scalp sites (C4 and C3). During RNB, the peak amplitudes of two negative components (viz. Na wave and Nb wave) were significantly increased on the right side. Increased peak amplitudes of Na and Nb waves suggested that RNB increased the number of neurons recruited on the right side, suggesting a possible application of RNB in certain psychiatric disorders with cerebral hemispheric imbalance.     

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.     

Brain stem auditory evoked potentials: the use of noise estimate

One of the main difficulties with the interpretation of evoked potential data is the question of how much noise is contained within the average. This question is crucial in deciding whether any particular peak component is a genuine signal, or whether it is a random occurrence due to noise. This is particularly crucial in abnormal cases, and with stimuli near sensory threshold. A simple method is described which allows on-line objective statistical determination of the presence of significant non-random peak components. It is shown that high signal-to-noise (S/N) estimates are seen with 'clean' and reproducible BAEPs and low S/N estimates are seen with poorly reproducible BAEPs. This provides an objective measure to judge the acceptability of any single BAEP, or to indicate that further averaging is required. The effect of noise on wave shape and peak latency is discussed. This can be quite marked, with gross distrotion of morphology and latency as a result. The technique lends itself to evoked response audiometry (ERA) and sensory threshold determination. Further, it can be applied to evoked potentials from other stimulus modalities.     

Brain stem auditory evoked potentials in "alcoholic epilepsy"

BAEPs were studied in a group of subjects suffering from 'alcoholic epilepsy.' Results were then compared with data from normal subjects and chronic alcoholics without epilepsy. The latency for peak V and the inter-peak latencies (I-III, III-V, I-V) were significantly longer in the 'alcoholic epilepsy' group than in the control group. This increase of neural transmission time in the brain-stem auditory pathways was less important in the 'chronic alcoholics without epilepsy' group than in the alcoholic epilepsy group.     

Brain stem auditory evoked potentials in children with partial seizures

BAEP were recorded in 34 children with partial seizures. Epilepsy with rolandic spikes and occipital paroxysms were excluded. Results were then compared with data from subjects without neurological diseases. Twelve children presented abnormal responses. There were no relationship between results of BAEP and either number of seizures, duration of epilepsy or therapy. Eight of 13 children with complex partial seizures showed abnormal BAEP. Prognostic value of results is discussed. This study shows that Brain stem may be involved in the neuronal dysfunction observed during partial epilepsy.     

Brain stem auditory evoked potentials in patients with cerebrovascular diseases

Brainstem auditory evoked responses (BAERs) were recorded in 30 patients with brainstem lesions. The aim of the study was to find the correlation between an abnormal BAER and the adequate level of a brainstem lesion. The correlation noted between an abnormal BAER and level of a brainstem lesion (medulla, pons, midbrain) was not statistically significant (p = 0.073 Kruskal-Wallis H-test). This could be explained partly by the fact that a brainstem generators for the BAERs are complex and the various components of the BAERs may actually depend on multiple generators. In patients with unilateral lesions the most prominent abnormality was noted in BAERs generated by stimulating the ear ipsilateral to the lesion, except for wave V. The present study supports the concept that ipsilateral pathway (uncrossed fibres) and crossing fibres contribute to its generation.     

Brain stem auditory, visual and somatosensory evoked potentials in leukodystrophies

Brain stem auditory (BAERs), visual (VEPs) and somatosensory evoked responses (SEPs) were recorded in 12 patients with Pelizaeus-Merzbacher leukodystrophy (PMD), three with adrenoleukodystrophy (ALD) and three with metachromatic leukodystrophy (MLD). All the 3 evoked responses were abnormal in all patients except normal VEPs and SEPs in a patient with early ALD. In most patients wave I with and without wave II were the only components of the BAERs that remained, subsequent components (waves III-VII) were absent. VEPs were severely altered; either no identifiable response to flash or pattern reversal stimuli could be recorded or the major components were significantly delayed in latency. Short latency SEPs following median nerve stimulation usually showed a normally recorded Erb's potential (N10), but an absence or marked attenuation of cervical (N14) and early scalp components (N19 and P22) or the occurrence of the scalp components with a significant delay. Multimodality evoked responses provide more information regarding the functional integrity of several afferent systems in patients with white matter disorders.     

Brain stem auditory evoked potentials in the normal and autistic child

From a neurophysiological viewpoint a hypothesis for the etiology of early infantile autism suggests that the symptoms are a result of abnormalities in processing sensory input at the level of the brain-stem. The methods for recording auditory evoked responses (BAERs) seemed particularly well suited to study a failure at this level. BAERs to brief monaural and binaural stimulation were studied in 17 autistic children ranging in age from 3 to 9 years (mean = 6.1). They were age and sex matched to normal controls. Electrodes were placed at the vertex and at the mastoid ipsilateral to the stimulation. Signals were amplified 10(5) using an amplifier with bandpass filters set at 160 Hz and 3 kHz. Stimuli were clicks (120 microsec) delivered to subjects through earphones at 2 intensities: 70 and 90 dB. Stimuli were presented in blocks of 3000 clicks (1500 clicks for each intensity) with a rate of 10/sec. No sedative medication was used. There was no difference between autistic and normal children for the latencies of peak I. Latencies of peaks II, III, IV and V were found to be shorter in autistic than in normal children. The I-II and II-III interpeak transmission times were significantly decreased in the autistic group, but not III-V interpeak transmission time. Autistic children showed V-VN amplitude greater than normal children. Our findings suggest that in the autistic syndrome, there is a defect of the modulation processing input related to intensity at brain-stem level.     

Postsynaptic potentials evoked in spiny neostriatal projection neurons by stimulation of ipsilateral and contralateral neocortex

Postsynaptic potentials were evoked in neostriatal neurons by stimulation of the ipsilateral and contralateral medial agranular frontal cortical field (AGm) in the rat. This cortical region is known to project bilaterally to the dorsal lateral head of the caudate-putamen of rats. Ipsilateral stimulation of AGm should excite all types of corticostriatal neurons projecting to neostriatal neurons in the corresponding area in neostriatum, while stimulation of the same cortical area on the side contralateral to the recording should evoke synaptic potentials from a more restricted subpopulation of crossed corticostriatal neurons. Neostriatal neuronal responses were recorded intracellularly and spiny projection neurons identified by intracellular staining with horseradish peroxidase. The initial EPSP response to contralateral stimulation was similar to that evoked from the ipsilateral side, except for the absence of a relatively small short latency component responsible for the earliest part of the response to ipsilateral cortical stimulation. Comparison with previous findings indicated that this earliest EPSP component was due to activation of fast-conducting descending cortical efferents with collateral projections exclusively to the ipsilateral neostriatum. Stimulation of contralateral neostriatum evoked responses identical to those obtained using stimulation of contralateral neocortex. Analyses of these responses indicated that both EPSPs arise from activation of the same population of fibers. Stimulation of the contralateral internal capsule just caudal to neostriatum was not effective in evoking the EPSP. Chronic hemidecortication did not change the shape of the EPSP evoked from the intact contralateral side, but reduced its amplitude by approximately one half. These observations indicate that contralaterally projecting corticostriatal neurons in the rat project bilaterally in neostriatum, have axonal branches to the contralateral cerebral cortex as well as neostriatum, and converge onto neostriatal neurons that also receive input from the corresponding cortical region on the ipsilateral side.     

Peak latency differences in evoked potentials elicited by painful dental and cutaneous stimulation

Long-latency evoked potentials (EPs) (50-400 msec) have been obtained from humans during both noxious stimulation of tooth and cutaneous sites in studies of pain and analgesic states. This study investigated whether EPs elicited by tooth and lip stimulation differed in peak latency and whether EPs obtained during painful cutaneous stimulation showed increasing peak latency values with increased conduction distance. Twelve volunteers received painful electrical stimulation at four sites: tooth, lip, thumb, and toe in counterbalanced orders. Evoked potentials recorded at vertex were summation averaged over 128 trials. Multivariate stepwise discriminate analysis was used to determine whether any of the peak latencies of the event-related potentials differed across stimulation sites. No significant latency differences were observed across lip, thumb or toe at any of the major peaks. Since peaks of these EPs did not vary in latency with conduction distance, they appear to reflect processing at higher levels rather than sensory transmission. The negative 140 msec peak of the dental waveform occurred significantly later than the same peak at cutaneous sites.     

Brain stem auditory evoked potentials in two siblings with Niemann-Pick disease

Niemann-Pick disease is a disorder of sphingomyelin metabolism, which produces organomegaly and progressive generalized neurologic dysfunction. In two brothers with Niemann-Pick disease type C brain stem auditory evoked potentials (BAEPs) produced prolongation of waves I-III interpeak latencies.     

Effects of attention on auditory evoked middle latency potentials

The effects of attention on the auditory evoked middle latency potentials (MLPs) were examined in 23 normal subjects. Early positive-negative-positive-negative waves (about 8, 11, 15 and 18 msec peak latencies) and a late positive one (about 30 msec peak latency) were recorded from the unilateral mastoid-nose tip. The amplitudes of the early portions of MLPs to binaural 50 dB SL clicks during attention decreased as compared to those obtained when the subjects were not attending to the test stimuli. No significant difference was seen in the latency of any early wave.     

Age-related changes in human middle latency auditory evoked potentials

We recorded middle latency auditory evoked potentials (MAEPs) in young (20-40 years) and elderly (60-80 years) subjects with normal hearing. The Pa component was prolonged in latency and markedly enhanced in amplitude in the elderly subjects. No changes were found in Na, or in the binaural interaction of the MAEP. Differences in Pa amplitude and latency were not due exclusively to changes in auditory thresholds, since they were not duplicated by changes in stimulus intensity, and persisted when MAEPs from selected young and old subjects were compared at similar SPL levels. The enhancement of Pa amplitude appears to reflect age-related central modifications in auditory processing.