Periodic Limb Movements in Complex Sleep Apnea Syndrome

ABSTRACT

Introduction: The development of repetitive central apneas during application of CPAP in patients initially showing obstructive apneas, a condition called complex sleep apnea syndrome (CompSAS), implies respiratory control instability. Respiratory control is known to be transiently destabilized by arousals. We hypothesized that PLMS and PLMrelated arousals would be more frequent in patients with CompSAS compared to those with obstructive sleep apnea (OSA) and could account for some of the respiratory instability.

Methodology: Comparative retrospective review of patients studied in our Sleep Disorders Center.

Results: 88 patients with CompSAS were compared with 112 patients with OSA. Total arousal index (TAI), respiratoryrelated arousal index (RRAI), and PLM-related arousal index (PLMAI) were similar during the diagnostic polysomnography of CompSAS and OSA patients. Following CPAP application, patients with CompSAS had a higher TAI [27.2 (15.5 – 39.9) vs. 16.6 (10.7 – 26.5); p≤0.001; median (interquartile range)], but a lower PLMI [0 (0 – 21.1) vs. 12.6 (0 – 36.2); p=0.009] and PLMAI [0 (0 – 1.3) vs. 0.8 (0 – 4.2); p=0.004] than patients with OSA.

Conclusion: PLMS and PLM-related arousals are not more common in CompSAS than in OSA patients and do not appear to play a significant role in destabilizing respiratory control in CompSAS patients.