Central auditory nervous system dysfunction in echolalic autistic individuals.

Accumulating evidence indicates either a primary or secondary cortical dysfunction in the language-dominant hemisphere of autistic children. In this study, the central auditory function of six autistic subjects was assessed experimentally using a battery of tests which included the Staggered Spondaic Word Test, the Competing Environmental Sound Test, and monaural hearing tests, as well as supplementary measures of language and handedness. The autistic subjects ranged from 8 to 24 years in age and displayed a wide range of language abilities and severity of echolalia. The results showed that all the subjects had normal hearing on the monaural speech tests; however, there was indication of central auditory nervous system dysfunction in the language dominant hemisphere, inferred from the dichotic tests, for those subjects displaying echolalia. Essentially normal dichotic test results were obtained for those subjects who were previously diagnosed as autistic but were not longer echolalic. One subject who received a year of intensive language treatment was assessed periodically throughout the year to chart changes in performance on the test of central auditory function for dichotic stimuli. This subject showed changes in the dichotic test of central auditory function which were consistent with the language improvement shown during the year. For each subject, the locus of central auditory dysfunction indicated by the assessment measures was consistent with the characterized language deficits. The results are discussed from a neurolinguistic framework in an effort to delineate a neurogenic etiology of autistic language deficits.