Association between restless legs syndrome and other movement disorders

Objectives. The present review focuses on the possible association between restless legs syndrome and movement disorders, including Parkinson’s disease, other parkinsonian syndromes, essential tremor, choreic and dystonic syndromes, Tourette’s syndrome and heredodegenerative ataxias.
Methods. Review of PubMed Database from 1966 to September 2018 and identification of references of interest for the topic. Meta-analysis of eligible studies on the frequency of RLS in Parkinson’s disease patients and controls using the Meta-DiSc1.1.1 software and using the PRISMA guidelines.
Results and conclusions. Although there are substantial clinical, neuroimaging, neuropathological and genetic differences between RLS and Parkinson’s disease, many reports describe a higher than expected prevalence of RLS in patients with Parkinson’s disease, when compared both with the general population or with matched control groups; several studies have also suggested that RLS could be an early clinical feature of Parkinson’s disease. RLS symptoms are very frequent in multiple system atrophy, essential tremor, Tourette’s syndrome, Friedreich ataxia, and spinocerebellar ataxia type 3 (SCA3) as well. Finally, possible genetic links between Parkinson’s disease and RLS (the presence of allele 2 of the complex microsatellite repeat Rep1 within the alpha-synuclein gene promoter) and between Tourette’s syndrome and RLS (several variants in the BTBD9 gene) have been reported in two case-control association studies, although these data, based on preliminary data with small sample sizes, need to be replicated in further studies.