Electrical auditory brain stem responses (EABR) and electrical middle latency responses (EMLR) were recorded from patients who had received the Nucleus multichannel cochlear implant system. Twenty-five sequential patients had either intraoperative or outpatient EABR testing. We also recorded EMLRs from several outpatients. EABR results were consistent among all patients tested. Wave V mean latencies were the shortest (3.82 msec) for the most apical electrode (E20) and increased slightly for the medial (E12) and basal (E5) electrodes (3.94 and 4.20 msec, respectively). Absolute latencies for all EABR component waves were observed to be 1 to 1.5 msec shorter than typical acoustic auditory brain stem response (ABR) mean latencies.
This study assesses several electrocochleographic (ECoG) duration and amplitude measures in a clinically defined Meniere's group and compares the results with those from a normal hearing control group and a hearing loss group (cochlear). The summating potential (SP)/action potential (AP) amplitude ratio was the most efficient diagnostic measure, with 62% of the Meniere's group demonstrating abnormal ratios compared to 4% of the normal control group and 17% of the cochlear group. The SP changes were then studied from three angles: 1. Comparison of SP changes with glycerol test results; 2. Comparison of ECoG results before and after shunt surgery; and 3. Recording of SP's in guinea pig ears in which hydrops had been created by obliterating the endolymphatic duct.
We have studied the prediction of behavioral threshold and comfort values for 11 patients who use the Nucleus 22-channel cochlear implant by means of the results of electrical auditory brain stem response (EABR) procedures. For prediction purposes, EABR and behavioral testing were done in the same electrode mode configuration for three specific electrodes. The results of this investigation suggest that EABR threshold current level is consistently near the behavioral comfort current level, rather than the patient's behavioral threshold level.
This paper deals with the surgical approaches to that part of the intratemporal facial nerve lying proximal to the cochleariform process and focuses on two issues: the advisability of disarticulating the ossicular chain to reach this area and the accessibility of the labyrinthine segment via the transmastoid, extralabyrinthine, subtemporal route. Relevant anatomical features, which are based on 39 gross temporal bones, 47 histologic sections, and 10 cadaveric specimens are first considered. In the head specimens, it was possible to attempt exploration of the entire nerve with the transmastoid, extralabyrinthine, subtemporal operation and then remove the labyrinth to gauge the adequacy of this approach as an avenue to the labyrinthine segment. These anatomical findings, their bearing on the questions at hand, and the author's clinical experience are incorporated into descriptions of the operations currently in vogue for exploring the proximal nerve in patients with Bell's palsy.
A group of 101 otologically normal infants and children were evaluated with low-frequency harmonic acceleration (HA) to determine the feasibility of use of this procedure in evaluation of vestibular function in a pediatric population. Ninety-six of the subjects were successfully tested and normative data are presented. A maturational trend was noted (in the presence of nystagmus) in subjects up to 10 months of age and in the phase-lag measurement up to approximately 4 years of age.
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