Auditory Brainstem Response Data Research Articles

Individual Differences in Auditory Electric Responses: Comparisons of Between-Subject and Within-Subject Variability IV.Latency-variability Comparisons in Early, Middle, and Late Responses

In this series of reports to date (Lauter & Loomis, 1986, 1988; Lauter & Karzon, 1990 a & b) we have described patterns of relative variability observed in latency and amplitude of auditory brainstem responses (ABRs) collected in a repeated-measures within-subjects design testing two groups of neurologically normal adults. Each of the two groups of subjects was additionally tested for one other type of auditory evoked potential, according to the same schedule of eight weekly sessions: middle-latency responses (MLRs: 10 to 50 ms post-stimulus) were collected from Group II (four females and four males), and late responses (50 to 300 ms post-stimulus) from Group I (four females and three males). This paper presents data comparing and contrasting the patterns of relative variability of waveform-peak latency observed in middle-latency, late responses, and the ABR data previously reported. Results document a trimodal distribution of response latency variability, with ABR peak V in one category, characterized by high within-subject stability and low between-subject stability, ABR peaks II, III, and IV, together with MLR peak No in a second category, of intermediate within-subject stability, and a third category consisting of ABR peak I together with all auditory-evoked-potential (AEP) peaks subsequent to MLR peak No, in which consistency of peak latency calculated within subjects approaches the low level of consistency calculated across subjects.

Statistical dependence among the wave latencies of the auditory brain stem response.

If the interpeak intervals in the auditory brain stem response (ABR) are assumed to be statistically independent variables that represent the neural transmission time between loci, then the absolute latency of an ABR wave is the sum of the transmission times between successive loci. Consequently, the correlations between the absolute latencies of the ABR waves would be part-whole correlations whose expected values are appreciably different from r = 0. We derived the expected values of the correlations between the latencies of the ABR waves on the assumption that their latencies are the sum of independent elements (transmission times) and found them to be 0.707, 0.577, and 0.816 for I.III, I.V, and III.V, respectively. In addition, the expected values of the correlations between the latencies of the ABR waves assuming that the absolute wave latencies themselves are independent variables (e.g., rI.III = 0) were derived. Several of the correlations among interpeak and between the interpeak and absolute latencies were demonstrated to be appreciably different from r = 0. It would appear that it is more reasonable to assume that the elements (transmission times) rather than the component latencies are the variables of choice for statistical analysis of ABR data.

Effects of maternal cocaine abuse on the neonatal auditory system

Eighteen neonates born to cocaine-abusing mothers were tested for peripheral and brainstem auditory dysfunction using auditory brainstem responses (ABR). Their data were compared to ABRs from 18 normal neonates. The ABR data were analyzed to determine if ABR parameters were abnormal in neonates born to cocaine-abusing mothers in comparison to normal neonates. ABRs from neonates exposed to maternal cocaine abuse show prolonged interpeak latencies and prolonged absolute latencies. These abnormalities indicate neurologic impairment or dysfunction that warrants further audiologic and neurologic follow-up.

Auditory brainstem responses in noise-induced permanent hearing loss.

Fifty-four patients (108 ears) with presumed noise-induced hearing loss, were subjected to tonal and speech audiometry, impedance tests and measurements of auditory brainstem responses (ABR), in order to check for possible retrocochlear involvement. ABR data indicated that latency values of waves I, III and V, as well as III-I, V-III and V-I intervals fell within the normal range in all cases (M +/- 2 SD), even for fast repetition rates (51 stim/s). Poor waveform resolution of early components, particularly of wave I, was found in 12 ears (11.1%) and a total absence of evoked potentials not always related to the hearing loss, occurred in 5 ears (4.6%).

Inaccuracies in the measurement of auditory brainstem response data in normal hearing and cochlear hearing loss.

In a test-retest experiment inaccuracies in the measurement of the peak latencies and threshold of the auditory brainstem response were determined for a group with normal hearing and for a group with cochlear hearing loss. The inaccuracy of the auditory brainstem response threshold is less than 4 dB in both groups. The inaccuracy in latency was measured as a function of stimulation level. In both groups the latency inaccuracy of peak V varies from 0.1 ms at levels well above threshold to 0.2 ms near the response threshold. Analysis of variance showed that in subjects with normal hearing the intra- and interindividual variabilities of the peak V latencies contribute about equally to the total variance at all stimulation levels. The implications that these findings have for the determination of the horizontal shift of the latency-intensity curve are discussed.

Brainstem response audiometry. II. Classification of hearing loss by discriminant analysis.

In the companion paper [V.d. Drift et al.; Audiology 27: 260-270, 1988], it was shown graphically that conductive and cochlear hearing loss can be distinguished on the basis of the combinations of the auditory brainstem response threshold with the horizontal shift of the latency-level curve of peak V, its derivative or the latency of peak V at threshold level, respectively. In addition to the patient data used in the companion paper, 22 patients with mixed hearing loss were enrolled in the present study. The statistical technique of discriminant analysis was applied to find the optimum linear combination of auditory brainstem response data for classification of a hearing loss. The brainstem classification 'cochlear hearing loss' agrees with the diagnosis on the basis of the pure-tone audiogram in 85% of the cases. In cases with the brainstem classification 'conductive hearing loss', 93% showed at least a conductive component in the pure-tone audiogram.

Auditory Brainstem and Middle-Latency Responses in Bell's Palsy: Les réponses du tronc cérébral et de latence moyenne dans la paralysie de Bell

Patients with acute peripheral facial palsy (Bell's palsy) were examined by auditory brainstem response (ABR) and middle-latency response (MLR) for signs of brainstem involvement. ABR data on 30 patients indicated that wave V latencies were abnormal by greater than 3 SD in only 2 patients, 1 of whom showed abnormality contralateral to the affected side. When the criterion for abnormality was reduced to 2 SD, wave V abnormality was found in only 3 of the 30 patients. All 14 patients tested by MLR showed normal responses. These findings suggest that on the basis of evoked potential measures, brainstem involvement may not be pathognomonic of Bell's palsy.

Decision analysis of auditory brainstem responses and rotational vestibular tests in acoustic tumor diagnosis.

This study addresses the problem of the escalation of the costs of medical care which make diagnosis of acoustic tumor expensive. Specifically, we examined the hypothesis that a test protocol of the auditory brainstem response (ABR) in parallel with sinusoidal harmonic acceleration (SHA) is more cost-effective in identification of the risk of tumor than ABR alone. The subjects were 74 patients with acoustic tumors and 78 controls. ABR and SHA data from these subjects were submitted to decision analysis. ABR was more cost-effective than the protocol of ABR in parallel with SHA. Using these data, we outlined a "decision tree" for acoustic tumor diagnosis that fit the goals of high sensitivity when earlier probability of tumor was high, and high specificity when earlier probability of tumor was low.

The effects of tocainide on audiological and electrophysiological responses in humans.

This study reports on the systematic audiological evaluation of 18 cardiac patients receiving tocainide, an orally administered cardiac antiarrhythmic agent. The results of an audiological site of lesion test battery were compared with auditory brain stem response (ABR) measures. Of 35 ears tested, 17 (48%) presented ABR findings consistent with retrocochlear pathology. Audiological signs of retrocochlear pathology occurred less frequently and often in patients in whom ABR results suggested normal hearing or cochlear hearing loss. These data demonstrate that an extraneous agent, in this case tocainide, can affect ABR transmission times and that it is important to recognize such possible effects in order to interpret ABR data appropriately.

337 THE RELATIONSHIP BETWEEN ABR AND CARDIOPULMONARY FUNCTION IN PRETERM LAMBS

The auditory brain-stem response (ABR) and cardiopulmonary function (as determined by the mean blood pressure [MBP], heart rate, arterial blood gases [ABG], and pH were evaluated in 9 preterm lambs ranging in age from 106-125 days gestation (70-85% term). Following epidural anesthesia of the ewe, the uterus was opened, the fetal head exposed, and a saline-filled rubber glove placed over the snout to prevent inspiration of air. Two platinum-alloy needle electrodes were inserted subdermally just posterior and inferior to the pinnae, another at vertex, and one in the snout area for ground. Click stimuli were generated and delivered by a bone conduction vibrator driven by 100 usec pulses of alternating polarity. Even the youngest group of animals revealed clearly defined 8th nerve and brain-stem response components. The latencies of waves 3,4, and 5 and the interpeak latency 1-5 decreased significantly as a function of age. Results of physiologic measures and the ABR data across subjects revealed a significant negative correlation between MBP and the latencies of waves 4 and 5 and the 1-5 interpeak latency and were suggestive of a possible inverse relationship between the wave 1 latency and pH. These findings demonstrate the presence of the ABR as early as 70% gestation as well as the sensitivity of the ABR to MBP and acid-base balance at this stage of development. (Supported by NIH Grant HL/HD 30525).

ABR IN EIGHTH-NERVE AND BRAIN-STEM DISORDERS

Auditory brain-stem response (ABR) results are reported on three cases of acoustic tumors and two cases with brain-stem lesions. These cases highlight several considerations in the clinical use of ABR. The sensitivity of ABR to retrocochlear involvement in light of normal pure-tone hearing and cochlear hearing loss is shown in the first two cases. The third case shows the advantage of "contralateral" ABR testing and a unique effect of stimulus polarity. The use of an intensity function and high presentation rate procedures are shown to be helpful diagnostic procedures in case four. Case five shows bilateral ABR effects which correlate well with the degree of brain-stem involvement. In addition to the ABR data, audiologic, radiologic, and medical findings on these patients are also discussed.