The high frequency of restless legs syndrome in patients with amyotrophic lateral sclerosis

Restless legs syndrome (RLS) appears to be more frequent in certain neurodegenerative disorders. The aim of our study was to determine the frequency and the determinants of the association of RLS with amyotrophic lateral sclerosis (ALS) in a French cohort. Information on sex, age, age at onset, site of onset, body mass index, disease duration, ALS Functional Rating Scale-Revised and use of technical supports was obtained in a cohort of 69 ALS subjects (69.6 ± 9.7 years). RLS was diagnosed using the International RLS Study Group criteria. We compared our frequency rates by age with frequency rates of RLS in the French general population from literature. RLS was observed in 13 patients (18.8%). Frequency of RLS was higher (p = 0.007) in ALS patients older than 64 years than in the French general population of the same age group. There were no further demographic, clinical or biological differences between the patients with RLS and those without RLS, with the exception of a higher frequency of difficulty turning in bed and adjusting bedclothes (p = 0.023). In conclusion, RLS occurs frequently in ALS, and those affected should be identified and appropriately treated.