Subclinical REM sleep behavior disorder in a patient with corticobasal degeneration

Various neurodegenerative diseases have been reported to be associated with rapid eye movement (REM) sleep behavior disorder (RBD). This is the first report of a patient with corticobasal degeneration (CBD) associated with subclinical RBD. A 72-year-old woman was admitted complaining of fine tremor of the right hand and weakness of the right lower extremity. She was diagnosed as having CBD on the basis of clinical features and neuroimaging studies. Her family noticed snoring and increase in sleep talk, but they did not regard them as pathological. All-night polysomnography (PSG) revealed REM sleep without atonia (RWA) during which 14 episodes of talking and singing were observed. They ranged from the utterance of one word to that of comprehensible words of a song for about 3 minutes accompanied by various nonpurposeful movements of the mouth, hands, and limbs. These episodes were not associated with any sleep-disturbed breathing. Future PSG studies on CBD patients together with postmortem analysis of brain stem structures that are crucial for generating REM sleep-related atonia are warranted for further understanding of the pathophysiological mechanism of RBD.