Previous studies of the neurobiology of autism that have used the
brainstem auditory evoked response have given contradictory results. The
authors of this study considered two supplementary aspects; they added an
ipsilateral masking procedure, and they compared the results for every
subject to the values (corrected for age and sex) of a large number of
normal children. Twenty autistic (according to DSM-III-R criteria) and 13
mentally retarded (nonverbal IQ less than 75) subjects were assessed.
Eighty percent of the autistic subjects had abnormal interpeak latencies,
compared to 15% of the mentally retarded subjects. The I-V and III-V
prolonged interpeak latency values were seen only in the autistic subjects.
The ipsilateral masking procedure doubled the rate of detection of
higher-brainstem abnormalities in the autistic children.