While Isolated Periodic Limb Movement Disorder Significantly Impacts Sleep Depth and Efficiency, Co-Morbid Restless Leg Syndrome Mainly Exacerbates Perceived Sleep Quality

Abstract

Background: Restless leg syndrome (RLS) and periodic limb movement (PLM) disorder (PLMD) can affect sleep quality and interfere with daytime functioning. Whether the co-morbidity of RLS further worsens daytime symptoms, sleep architecture and quality in patients with PLMs, is not yet fully clarified. Methods: Sleep (polysomnography) and daytime symptoms of 47 drug-free patients, assigned to isolated PLMD or co-morbid RLS subgroups, were compared to controls in a retrospective cohort-study (n = 501). Associations between perceived sleep quality, fatigue, sleepiness, mood and sleep variables were explored descriptively. Results: Although co-morbid patients showed worsened sleep quality, both patient groups showed similar sleepiness and affective symptoms. While significantly differing from controls, patients presented similarly increased light sleep, decreased slow-wave sleep and lowered sleep efficiency. Altered sleep quality, fatigue and sleepiness were significantly correlated to decreased slow-wave sleep and sleep fragmentation. Affective symptoms, fatigue and perceived sleep quality also correlated to PLM index. Conclusions: Sleep structure and efficiency were similarly impacted in isolated PLMD and in co-morbid RLS. RLS mainly worsened perceived sleep quality. Given that systematic treatment for isolated PLMD is currently not recommended, such results may question whether no or different-from-RLS treatment strategies are compatible with optimal care.

Difference in Psychological Distress between Patients with Periodic Limb Movement Disorder and Restless Legs Syndrome

“…The sleep disturbance is considered the reason for psychosomatic distress in RLS patients [25]. Previous studies have also reported that PLMD patients have worse insomnia symptoms [31] and impaired sleep quality than good sleepers [11], which is consistent with our findings in this study. The PLMD patients exhibited sleep disturbance on PSG and in- somnia symptoms similar to those in the patients with RLS.…”

“…A previous study reported elevated SCL-90-R domain scores in all but the I-S and PAR domains in RLS patients compared with healthy controls [17]; similar results were demonstrated in our study. A recent study reported similar depressive and anxiety symptoms between RLS and PLMD patients [11]. However, the patients with PLMD in our study demonstrated a higher SCL-90-R score only in the HOS domain.…”

“…This difference may be due to the different demographic characteristics of the PLMD patients. The PLMD sample in our study included more males (65.0% vs. 37.5%) and older individuals (mean age 55.0 ± 12.0 vs. 45.5 ± 8.9) than the previous report [11].…”

“…PLMD is also known to be associated with depression and anxiety disorder [10]. A recent study reported similar degrees of sleepiness, depression and anxiety between patients with PLMD and those with RLS [11].…”

Sleep Abnormalities in Multiple Sclerosis

“…RLS is mainly a wake-related disorder, characterized by an irresistible need to move the legs, usually accompanied by unpleasant sensations which begins or worsen during inactivity, especially in the evening/night, and improves or disappears by movement [44]. On the other hand, PLMD is a sleep-related condition, appearing mainly in the lower limbs and involving stereotyped involuntary movements (periodic limp movement-PLM) such as the extension of the big toe, often combined with a partial flexion of the ankle, the knee, and in some cases, the hip; those symptoms are often associated with cortical and/or autonomic arousals or with an awakening affecting significantly the patients quality of sleep [45].…”