An analysis of the human brain stem auditory evoked response yielding new criteria for defining its abnormality

The human brain stem auditory evoked response (BAER) is analysed into 3 main constituent components: a slow background wave, a repetitive wave, and a 3rd (delayed) component which is of relatively short duration, and which does not begin until about 5 ms after the click stimulus. In a group of responses from healthy subjects, the amplitude and latency variabilities of the delayed component are found to be small. In the BAER, as usually recorded from vertex-ipsilateral earlobe electrodes, the peaks I, II, III, IV and VI are identified with the crests of the repetitive wave. Based on this correlation, it is suggested that these peaks may be generated from a common source. Existing criteria for defining abnormality of the BAER are interpreted in terms of the constituent components found from the analysis. New criteria are proposed which involve the amplitudes and latencies of these components.