Periodic limb movement in sleep before and after continuous positive airway pressure titration in obstructive sleep-apnea patients

Background
Periodic limb movement during sleep (PLMS) could exist with patients diagnosed as obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) is the most competent therapy for OSA. However, its effect on PLM remains controversial.


Aim
To evaluate PLMS prevalence in OSA patients and the impact of CPAP titration on PLM outcome.


Patients and methods
Patients with history suggestive of OSA underwent full attended diagnostic and CPAP titration sleep study. On baseline polysomnography, OSA patients with PLM less than 5 were considered pure OSA and those with periodic limb-movement index more than or equal to 5 were considered combined group. Post-CPAP titration, patients were considered CPAP responders, CPAP persistent, CPAP emergent, or non-PLM group according to response of PLM.


Results
Out of 100 included OSA patients, the combined group was found in 53 patients. CPAP responder group was reported in 27 patients, while 25 and 24 patients were considered CPAP persistent and CPAP emergent, respectively. CPAP-emergent group showed significantly higher apnea–hypopnea index (AHI) than non-PLM group on baseline polysomnography. On the other hand, AHI was comparable in CPAP-persistent and responder group, despite normalization of AHI in both groups after titration. On multivariate regression analysis, old age was found to be an independent predictor for both persistence and emergence of PLM and higher AHI was an independent predictor in CPAP-emergent group.


Conclusion
PLMS can coexist with OSA in old-age patients, which may persist after CPAP titration. Elderly patients, especially those with baseline higher AHI, may also present with CPAP-emergent PLMS.