The Effects of Obstructive Sleep Apnea Syndrome on Periodic Limb Movements in Sleep

Seo, C S; Youn, T; Kim, E J; Jeong, D U

Abstract

OBJECTIVES
Periodic limb movements in sleep(PLMS) is a moderately prevalent disorder, of which pathophysiology remains largely unknown. PLMS has been reported to be common in patients with obstructive sleep apnea syndrome(OSAS), but reports on their relationship have been inconsistent in previous studies. Inconsistency of results maybe attributable to insufficient number of the study subjects We attempted to explore the influence of OSAS on PLMS in a large number of subjects.
METHODS
Three hundred and twenty subjects(M:F=192 : 128) with PLMS, as identified by the nocturnal polysomnography were studied. Sample mean age was 53.1(SD=15.1) years and their mean periodic limb movement index (PLMI) is 25.2/hr (SD=24.8). PLMS subjects were divided into two groups, based on the presence or absence of OSAS. Periodic limb movement indices and sleep paramenters between two groups were analyzed to evaluated the effects of OSAS on PLMS.
RESULTS
Each of PLMI and PLMI with arousal (PLMAI) correlated positively with age. PLMI of men was larger than that of women (p<0.01). The presence of comorbid OSAS independently had influence on PLMI(t=-2.20, p<0.05), but not PLMAI. There were no significant differences between the two groups in their PLMI. PLMAI and sleep parameters. However, the two groups differed in PLMI-correlated sleep parameters. In PLMS subjects with comobid OSAS, PLMI was negatively correlated with each of slow wave sleep time and REM sleep time. In subjects without comorbid OSAS, PLMI was negatively correlated with sleep efficiency.
CONCLUSION
PLMS patients with OSAS turned out to have increased PLMI than those without OSAS. We suggest that OSAS patients may have subtle autonomic arousals and these arousals could, in part, express themselves as PLM.