Abstract
Abstract
Introduction
REM sleep without atonia (RSWA) occurs in up to 90% of narcolepsy patients. REM behavior disorder (RBD), however, is reported to occur in only 12% to 36% of patients with narcolepsy. Use of RSWA has been proposed as an additional marker for narcolepsy diagnosis and as a tool to differentiate between narcolepsy and idiopathic hypersomnia. We describe a case of narcolepsy without cataplexy (N-C) with RSWA on polysomnogram (PSG), but no RBD on PSG or by history.
Report of Case
A 26 year old female with history of depression, anxiety, and migraine headaches presented with excessive daytime sleepiness requiring daytime naps since childhood. She endorsed sleep paralysis but not hypnagogic hallucinations, dream enactment or cataplexy. Sleep disordered breathing or other abnormalities were absent on overnight PSG. RSWA was seen, however, video recording did not reveal dream enactment behavior. The subsequent multiple sleep latency test showed a mean sleep latency of 3 minutes over 5 naps and 2 sleep onset REM periods.
Conclusion
REM related motor findings occur at a higher frequency in patients with narcolepsy than in the general population. Hypocretin deficiency is believed to be the major determinant of REM sleep motor dysregulation observed in narcolepsy. Patients with narcolepsy with cataplexy (N+C) are more frequently involved than patients with N-C.
RBD associated with narcolepsy differs from idiopathic RBD in that it has equal gender predominance, earlier age at onset, and is associated with less violent and less complex behaviors. Interestingly, RSWA may be absent in RBD with narcolepsy. In addition, RSWA in narcolepsy is frequent even in the absence of RBD. This highlights the need to develop diagnostic criteria for RBD specific to the context of narcolepsy.
RSWA is seen in high frequency in narcolepsy and should be strongly considered as a secondary diagnostic criteria.