BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is associated with repeated apnea-induced sympathetic surges leading to specific alterations of the power spectrum of heart rate variability (HRV). Sympathetic dysfunction evolves early in idiopathic Parkinson's disease (PD), but the consequences on cardiac autonomic response to OSAS have not been studied so far in PD patients.
METHODS: Sixty-two patients with PD (35 without OSAS (PD-wo), 27 with OSAS (PD-OSAS)) and 62 age-matched control subjects (25 without OSAS (Co-wo), 37 with OSAS (Co-OSAS)) were included. HRV variables - including mean R-R interval, standard deviation of all normal-to-normal R-R intervals (SDNN), both low frequency (LF) and high frequency (HF) power bands, and the LF/HF ratio - were computed automatically from full-night polysomnography and calculated separately for each sleep stage.
RESULTS: HRV variables were similar in PD-wo and PD-OSAS. In contrast, Co-OSAS showed significantly higher LF power in NREM1 and NREM2 sleep and higher LF/HF ratio in NREM1, NREM2 and slow wave sleep than Co-wo. Similarly, correlations between HRV variables and parameters of OSAS severity were found only in controls but not in PD patients.
CONCLUSION: Our results suggest that the sympathetic response to OSAS is blunted in PD, giving further clinical evidence of the sympathetic denervation commonly observed in this neurodegenerative disorder.