Brain stem auditory evoked potentials: significant latency differences between ipsilateral and contralateral stimulation.

A number of electrical potentials can be recorded from the human scalp following acoustic stimulation. The potentials which occur within 10 msec of the stimulus onset have been termed the brain stem auditory evoked potentials (BAEPs). Latency appears to be the most stable measure and in consequence knowledge of the exact limits of normal latency of each wave is important. In this study the effects of ipsilateral and contralateral stimulation on BAEP latencies have been investigated in 23 normal subjects. The exact limits of normal latency of each wave have been established. It has been shown that significant latency differences exist between ipsilateral and contralateral stimulation. Possible hypotheses are put forward to explain the findings which demonstrate that different neural pathways are followed by ipsilateral and contralateral stimuli and that their respective responses can be investigated separately in man using BAEP recordings.