Evoked potentials in the Rett syndrome.

In order to have an electrophysiological approach to the pathogenesis of the Rett syndrome (RS), EEG testing together with evoked potential studies were performed in five children with RS, observed in our hospital during the last three years. All of the patients, aged from 18 months up to 4.5 years, had abnormal EEG: normal background activity with paroxysmal, epileptiform discharges was seen. In contrast with the abnormal EEGs, the evoked potentials were normal in each patient: brainstem auditory evoked potentials (BAEP), visual evoked potentials (VEP), and central conduction time (CCT) of somatosensory evoked potentials (SSEP). These findings together with the few previous ones suggest a predominantly gray matter pathophysiology in the early stages of RS.