Periodic limb movements in sleep: to treat or not to treat?

Abstract

Background: Approximately 50% of our patients with sleep disturbances have periodic limb movements in sleep (PLMS). We have found that a high PLMS index is not correlated with the severity of symptoms on the Epworth Sleepiness Scale or response to pharmacologic therapy for restless legs syndrome (RLS)/PLMS. We hypothesized that differences in rhythm of contraction, predominance of periodic leg movements (PLMs) in different sleep stages, or PLM interval might distinguish responders from nonresponders.

Methods: We analyzed the hypnograms of 20 consecutive patients with PLMS, noting the number of PLMs and the PLM intervals in different sleep stages, the PLMS index, and the percentage of PLMs that led to arousals.

Results: We distinguished two groups of patients. The 13 patients in group A had a PLM arousal percentage of 10.9+/-5% (mean+/-SD), compared with 41.9+/-9% for the seven patients in group B. Group B had a lower PLMS index. Group A showed little variance in PLM intervals and experienced more delta sleep.

Conclusions: PLMS index was not correlated with arousals. A strict rhythm of contractions was associated with fewer arousals and better quality of sleep. This subgroup may not benefit substantially from specific RLS/PLMS therapy.