Rett syndrome due to mutation in the MECP2 gene and electroencephalographic findings

A 6-year-old girl with MECP2-positive Rett syndrome presented for investigation of seizures. The electroencephalogram (EEG) showed markedly disorganized cerebral activity, epileptiform paroxysms and a quasiperiodic pattern, followed by attenuation after paroxysmal activity. InMECP2-positive patients, there is a progression of EEG findings in stages. First, seizures are not a prominent feature, and the EEG may be normal. Second, focal spikes may be observed, especially in the centrotemporal regions. Third, there is an accentuation of epileptiform activity, abnormalities during sleep, and the presence of bilaterally synchronous discharges of pseudoperiodic delta activityandgeneralized rhythmic spikedischarges. Fourth, there are theta waves in the central and frontal regions, multifocal epileptiform activity in the waking state, and generalized slow spike and wave activity during sleep.