Neurophysiological findings in the Rett syndrome, II: Visual and auditory brainstem, middle and late evoked responses.

Nine girls with the Rett syndrome (RS) were investigated neurophysiologically using evoked potentials techniques. Visual- (VER) and auditory-evoked responses, including the early (ABR), middle (MLR) and late components (ACR), were recorded. There was evidence of variable, multilevel impairment of the nervous system. While ABR and MLR indicated lesions at the brainstem and midbrain levels, the late responses and VER pointed to an intra-cerebral/cortical defect. It is suggested that the perceptual mechanisms still functioned and some discrimination properties remained.