Polysomnography in the Rett syndrome

The features of sleep parameters in the Rett syndrome were compared with those in early infantile autism (EIA) and hereditary progressive dystonia with marked diurnal fluctuation (HPD). The sleep-wakefulness cycle and the tonic and phasic components of sleep were evaluated in each disorder, the former was estimated by the day-by-day plot method and the latter two by polysomnography (PSG) following our method. Abnormalities of the sleep-wakefulness cycle were observed in the Rett syndrome and EIA, but in the latter these abnormalities became inapparent with age and improved markedly by correcting the environmental condition and completely by 5-hydroxytriptophan. The latter, if treated early, was followed by improvement of behavior. In the Rett syndrome, however, the abnormalities continued into late childhood to adolescence. In HPD, PSG abnormalities were restricted to the phasic component, which improved completely after levodopa in accordance with the clinical improvement. On the other hand, in the Rett syndrome as well as in EIA both the phasic and tonic components were involved and also the leakage of the components of REM stage into NREM stage was observed. In the Rett syndrome, these abnormalities aggravated with age, with disturbances in % sleep stage, nocturnal variation of tonic and phasic components of sleep and REM-NREM cycles, while in EIA the results of PSGs revealed no such progressions but showed an increase in twitch movement and a lack of normal increase in the number of REMs occurring in short intervals.(ABSTRACT TRUNCATED AT 250 WORDS)