Disturbance of rapid eye movement sleep in spinocerebellar ataxia type 2.

Five genetically confirmed spinocerebellar ataxia type 2 (SCA2) patients were admitted to our sleep laboratory for two all-night video-polysomnographies. A standard montage was used, including electroencephalography, vertical and horizontal electrooculography, electromyography of mental, submental, and tibialis anterior muscles, and respiratory monitoring. Four of five SCA2 patients had insufficient muscle atonia during rapid eye movement (REM) sleep. All patients exhibited myoclonic jerks during REM sleep, while elaborated behavior was not observed in the video. Abnormal motor control during sleep with periodic leg movements and REM sleep without atonia occurs frequently in SCA2. This finding may reflect a dysfunction of dopaminergic and/or brainstem and cerebellar outflow pathways.