Effects of Varying Stimulus Polarity on Brainstem Auditory Evoked? Potentials

J Korean Neurol Assoc > Volume 7(1); 1989 > Article

Journal of the Korean Neurological Association 1989;7(1): 268-275.

청신경의 가압, 감압 및 교호자극에 의한 청각뇌간유발전위 (BAEP) ?반응의 변동에 관한 연구

하정상, 이상도,박영춘

영남대학교 신경과. 계명대학교 신경과.

Effects of Varying Stimulus Polarity on Brainstem Auditory Evoked? Potentials

Jung-sang Hah,M.D., Sang-Doe Yi,M.D., Young-Choon Park,M.D.

Department of neurology , College of medicine, YoungNam University Department of neurology , College of medicine, Keimyung University

Abstract

In order to observe the effects of various click polarity and stimulus rate on brainstem auditory evoked potentials (BAEPs), we measured the absolute latency, interwave latency and amplitude. Variations of IV-V wave complex in different stimulus rate and polarity were also observed. Observations were made on 50 normal subjects(32 males and 18 females) aged 8 to 56. The results are summarized as follows, 1. With rarefaction click stimulation, the absolute latencies of wave I and wave V were shortest, and wave I and wave III amplitudes were most increased as compared with condensation or alternating-polarity. 2. The absolute latencies of wave I and wave V were most prolonged and wave V amplitude was highest with condensation clicks. 3. I - III, III -V and I - V interwave latencies were not significantly changed between any of polarities. 4. By increasing stimulus rate from 10 click / sec to 50 click / sec, absolute and interwave latencies were significantly prolonged. Except wave V amplitude at condensation and alter-nating-polarity clicks, all wave amplitudes were decreased significantly. 5. The waveforms were classified into 5 types according to configuration of IV - V wave complex. At any conditions, type A and B were present most frequently. We proposed that if one is to employ only a single stimulus polarity, rarefaction clicks should be used because this will produce the earliest and largest wave I. Condensation can be used in those cases in whom rarefaction does not produce clar waveforms, or when wave V appears absent. The use of alternating-polarity clicks as the only mode of stimulation is discouraged because of the possibility of phase cancellations.