Autism in tuberous sclerosis: evoked potential evidence for a deficit in auditory sensory processing

Objective: Autism is a frequent manifestation of tuberous sclerosis complex (TSC) being reported in up to 60% of the patients. Its presence is in asso ciation with cortical. and subcortical lesions involving the temporal lobes . This study was designed to shed light on the functional mechanisms linkin g anatomical lesions of TSC and behavioural phenotype by investigating scal p recorded event related potentials to auditory stimuli. Methods: Fourteen children with TSC, seven of which fulfilled the DSM TV cr iteria for autistic disorder were selected for this study. All of the subje cts underwent high resolution MRI, EEG, brainstem auditory evoked potential s, cognitive and behavioural evaluation. Electrical evoked responses to two different pitches, presented with different probability (80% 1000 Hz, 20% 1500 Hz) were recorded from 21 scalp electrodes in the autistic and non-aut istic subgroups, to assess central auditory processing and automatic memory . Results: The first component of the long latency auditory response (N1) had a significantly prolonged latency with lower amplitude in all of the patie nts with autistic behaviour who, contrary to non-autistics had MRI lesions involving one or both temporal lobes. A mismatch negativity was detected in all subjects and had a longer latency in subjects with autistic behaviour. Conclusions: To our knowledge this is the first electrophysiological eviden ce of a deficit in auditory information processing and automatic memory in TSC patients with autistic behaviour. (C) 1999 Elsevier Science Ireland Ltd . All rights reserved.