Pedunculopontine nucleus stimulation influences REM sleep in Parkinson's disease

OBJECTIVE: To investigate the sleep-wake cycle and the effects of cabergoline monotherapy in a homogenous group of de novo Parkinson's Disease (PD) patients without confounding comorbid factors. DESIGN AND PARTICIPANTS: Twelve de novo patients affected by idiopathic PD underwent two ambulatory polysomnographic (APSG)monitoring sessions. The first was performed at baseline, and the second recording one-month after stable treatment with cabergoline monotherapy. Subjective daytime sleepiness was evaluated by means of the Epworth Sleepiness Scale.Data obtained in PD patients at baseline were compared with those obtained in 12 age- and sex-matched healthy subjects. RESULTS: Diurnal sleep parameters did not show significant differences between controls and PD patients at baseline. In PD patients, no significant changes in diurnal sleep were observed between baseline and cabergoline treatment. Regarding nocturnal sleep, patients at baseline showed a significantly lower sleep efficiency and a significantly higher Wakefulness After Sleep Onset than controls. With respect to baseline, a significant increase in REM latency and a significant reduction in REM sleep were observed during cabergoline treatment. CONCLUSIONS: In the early stage of PD, the neurodegenerative process does not seem to be directly responsible for daytime somnolence, but it may be directly involved in the alteration of nocturnal sleep. Cabergoline monotherapy does not affect daytime sleep propensity and, despite clinical improvement, it may have negative effects on REM sleep.