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 PLM- related 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), respiratory- related arousal index (RRAI), and PLM-related arousal index (PLMAI) were similar during the diagnostic polysomnogra- phy 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.