Clinical correlates of periodic limb movements in sleep in Parkinson's disease

Objective: The aim of the current study was to investigate the frequency of periodic limb movements in sleep (PLMS) in Parkinson's disease (PD) and their impact on nocturnal sleep and daytime functioning. Methods: Forty-five PD patients (mean age 68.5 ± 8.7 years; 32 males) underwent one night of polysomnography (PSG). Clinical assessment and questionnaires evaluating sleep disturbance and quality of life (QoL) were completed. Patients were divided into two groups based on their PLMS index (PLMSI): PLMSI ≥ 15 (PLMS +) and PLMSI < 15 (PLMS -). Results: There were 26 (57.8%) PD patients in the PLMS + group and 19 (42.2%) patients in the PLMS - group. Subjective assessment revealed an association between PLMS + status and greater PD symptom severity, more subjective sleep disturbance, and decreased QoL. All patients showed poor sleep, and no significant group differences were detected on PSG measures. Conclusion: We observed that PLMS occurred frequently in PD and increased with more severe PD. Although PLMS did not affect objective sleep, it was associated with increased sleep complaints and reduced QoL. Overall, our findings support the association between PLMS and PD as well as the clinical relevance of sleep disturbances in PD.