Evaluating the Differential Effects of Dopamine Agonists and Clonazepam on Large Muscle Group Movements in Restless Legs Syndrome.

Study objectives: This study aimed to investigate the effect of dopamine agonists (DA) and Clonazepam on Large Muscle Group Movements during sleep (LMM), a distinct motor phenomenon, in Restless Legs Syndrome (RLS).

Methods: A retrospective analysis was conducted on 51 drug-free adult patients with RLS, divided into three groups: 33 received a DA (pramipexole or ropinirole), 15 received clonazepam, and 18 received a placebo. Each patient underwent two consecutive nocturnal polysomnographic (PSG) recordings: one baseline and one following treatment administration. LMM and periodic leg movements during sleep (PLMS) were scored. Differences between groups were analyzed using ANCOVA, with the International Restless Legs Syndrome Study Group severity scale as a covariate, and within-group changes were assessed using paired t-tests.

Results: At baseline, no significant difference in LMM or PLMS was observed between groups. Following treatment, DA significantly reduced PLMS and periodicity indexes but did not significantly alter LMM indexes, except for a small increase in LMM duration. The placebo group exhibited a significant decrease in LMM index during the second night, potentially reflecting a first-night effect (FNE). Clonazepam did not significantly affect either PLMS or LMM.

Conclusions: DA effectively reduced PLMS but did not significantly impact LMM, suggesting that LMM may involve different neurophysiological mechanisms. The potential FNE observed in the placebo group underscores the need for careful consideration of adaptation effects in sleep studies. Future research should explore alternative or adjunctive therapies targeting LMM and residual sleep disturbances in RLS.