Early behavior characteristics and sleep disturbance in Rett syndrome.

This paper reviews the early features of Rett syndrome (RTT). The behavioral characteristics of RTT were analyzed retrospectively by taking history and asking about early infancy behaviors. The earliest behavioral characteristics are thought to be autistic features and hypotonia of trunkal muscles. Analysis of sleep-wake rhythm and all-night polysomnography suggested that the initial lesion is serotonergic and noradrenargic hypofunction at brainstem level. Dopaminergic (DA) hypofunction associated with DA receptor supersensitivity follows as the brain matures. Characteristic symptoms developing at specific age ranges are based on the neuronal connections of the brainstem aminergic neurons and DA neurons with the pedunculo-pontine nuclei, projecting to specific cortical areas.