Several reports describe a possible association between restless legs syndrome (RLS) and Parkinson disease (PD), as well as Tourette syndrome (TS) and RLS, according to a literature review published in Neurology.
RLS is a common sensorimotor disorder, and epidemiologic studies have demonstrated an association between it and other movement disorders such as PD, essential tremor, choreic and dystonic syndromes, TS, and heredodegenerative ataxias. However, the underlying pathophysiologic associations are unclear, and therefore researchers conducted a meta-analysis of eligible studies that focus on the possible association between RLS and other movement disorders, and discussed the possible common pathophysiologic mechanisms.
They found that although RLS and PD are clearly distinct entities from the clinical, neuroimaging, neuropathologic, and genetic points of view, these 2 disorders both respond similarly to dopaminergic drugs. However, the main support for the hypothesis of a possible association between RLS and PD arises from studies that have demonstrated a high prevalence of RLS symptoms in patients with PD. In addition, several studies have shown an increased frequency of incident PD in patients with RLS, which has been interpreted as RLS being an early clinical feature of PD. RLS symptoms are also common in patients with multiple system atrophy, essential tremor, Tourette syndrome, Friedreich ataxia, and spinocerebellar ataxia type 3, and possible genetic links between PD and RLS and between TS and RLS have been reported.
The investigators point out that the difficulty in differentiating between advanced PD and RLS, as well as the variability in diagnostic criteria for RLS, must be taken into account as a potential limitation of this study. They do, however, go on to state that, “[a]s a general conclusion, epidemiologic evidence supports association of RLS with other movement disorders, but further studies are required to confirm such hypothesis.” In addition, this study summarized the minimum requirements for future studies to address these possible associations between RLS and other movement disorders such as PD, essential tremor, and TS.
Alonso-Navarro H, García-Martín E, Agúndez JAG, et al. Association between restless legs syndrome and other movement disorders. Neurology. 2019;92:1-17.