Abstract
In 29 infants with infantile spasms, development quotients of auditory behaviors (DQ), thresholds of conditioned orientation reflex audiometry (COR), auditory brain stem responses (ABRs), slow vertex responses (SVR) and visual evoked responses (VER) were studied to determine the level of the lesion causing their hearing disorders. Seventy six percent of infants with infantile spasms showed severely delayed development quotients (below 33%), and 86.2% of these were found to have a moderate elevation of the COR threshold. ABR thresholds, peak latencies of waves I and V, and the interwave latency between waves I and V were measured. 27.6% of our cases were found to have the ABR abnormalities. One case (3.4%) had peripheral hearing loss and 24.2% had brain stem lesions. Cerebral evoked responses were evaluated as positive when reproducible responses were recorded. Slow vertex responses to 85-dB click stimuli were present in 20.7% and photically visual evoked responses were present in 41.4% of cases. These results revealed that a fourth Of our cases had brain stem lesions at least, but that others, except an infant with peripheral hearing loss, had essentially normal function at the brain stem level even though they responded to sound stimuli as poorly as deaf infants. In conclusion, a single lesion site in the auditory nervous systems of infnats with infantile spasms was not identified. Each case might have some variable lesions between the lower brain stem and cerebrum.
