[Brain-stem auditory evoked potentials and median latency in children with Down's syndrome]

We studied 20 milliseconds of the brainstem auditory evoked responses and 50 milliseconds of the middle latency responses in 11 children with Down's syndrome, between 6-9 years of age. The results were compared with those from 10 control children. We found a significative reduction of the amplitude of waves I, III, V in the former group. Central transmission time was shortest and frequently wave Pa was absent in patients with Down's syndrome patients. We hypothesized that the abnormalities of amplitude of the evoked responses may be related to presence of less neurons in the brain of patients with Down's syndrome. The reduction of central transmission time may be related to presence of microcephalia and significantly accelerated rates of action potential depolarization, repolarization and decreased spike duration. Wave Pa may have been absent due to microgyria of Heschl's temporal gyrus previously reported in patients with Down's syndrome.