Background: Many patients with obstructive sleep apnea (OSA) report no improvement in the excessive daytime sleepiness, despite compliant CPAP treatment. Associated periodic limb movements (PLMs)with OSA might be a cause of failure. Objectives: Our study aimed to assess the increased periodic limb movements index (PLMI) in patients with residual excessive sleepiness (RES) on CPAP and polysomnographic changes caused by the occurrence of PLMs in this group of patients, and predictors of PLMS's presence.
Patients and methods: We searched the electronic medical records of the OSA patients who were followed up in the CPAP outpatient clinic between 2010-2015. Patients who had completed at least one year of treatment were assessed. We included only patients with OSA and RES due to only PLMs (45 patients) (group one) against patients with OSAS, RES and with no definite cause (11 patients) (group two).
Results: There was significant difference between both groups(more in group one) in the age and waist circumference (p value 0.04 and 0.017, respectively). There was significantly longer sleep onset latency (28.01 vs. 9.29), lower total sleep time (5.5 vs. 6.6 hours) and lower sleep efficiency percentage (72.44% vs. 87.1 %) in group one than in group two (P-value of 0.042, 0.019 and 0.011, respectively). Also, there were significantly higher means of wake after sleep onset (WASO) and total arousal index in group one than in group two. Waist circumference was the only predictor for increased PLMs index in this population study, by logistic regression with OR (95%CI) 0.168 (0.011-0.324).
Conclusion: Increased PLMI during sleep significantly impact the polysomnographic variables. The waist circumference might be the only predictor of increased PLMs index.