Restless legs syndrome and motor activity during sleep in spinocerebellar ataxia type 6

BACKGROUND AND PURPOSE: We investigated the frequency of restless legs syndrome (RLS) and sleep disturbance in spinocerebellar ataxia type 6 (SCA6). PATIENTS AND METHODS: Five patients out of three multigenerational SCA6 families underwent a standardized investigation protocol including clinical interview for RLS, neurophysiological evaluation as well as the clinical assessment of ataxia. Polysomnography (PSG) was performed during two consecutive nights. RESULTS: Two out of five patients fulfilled the clinical criteria for RLS. A periodic leg movements in sleep (PLMS) index>15/h was present in four of the five patients; a PLMS index>5/h was present in all patients. Significant disturbance of rapid eye movement (REM) sleep was not found. None of the patients had REM sleep behaviour disorder. Only one patient had mild REM sleep without atonia. CONCLUSIONS: Our pilot study suggests only minor sleep abnormalities in SCA6.