Recognizability of brain stem auditory evoked potential components

In examining neurological patients suspected of having a brain stem lesion with brain stem auditory evoked potentials (BAEPs), a technique giving high amplitudes and/or maximal recognizability of most of the components was preferred. An increase of interstimulus intervals and stimulus strength and a widening of the band-passes of the amplifier were found to increase the amplitudes and the recognizability in BAEPs from normal subjects and patients. A random monaural 75 dBHL stimulation with 230 msec intervals and frequency cut-offs of the amplifier of 50–5,000 c/sec was chosen as the standard procedure. In normal subjects aged 10–69 years, a decrease in amplitudes was found with increasing age. Men older than 50 years had longer latencies than younger men. Women had shorter latencies and higher amplitudes than men. Waves I, III and V were recognized in all normal subjects; the recognizability of waves II, IV and VI was 94% or more in subjects younger than 50 years, 85–93% in the oldest subjects.