Objective: There have been many studies of the prevalence of restless legs syndrome (RLS) in Parkinson’s disease (PD).
Some studies found a lower prevalence than in comparable groups in the general population while others reported more RLS.
The present study was designed to determine the prevalence of primary RLS in Thai PD patients.

Material and Method: PD patients were interviewed for RLS symptoms and were excluded if they had a malignancy, endstage
renal disease, neuropathy, a history of spinal cord diseases or were pregnant. Serum ferritin levels were measured.

Results: Three out of 183 patients interviewed (1.6%) had symptoms consistent with RLS. When one patient who had a serum
ferritin level of 31.9 ng/ml is excluded, the prevalence falls to 0.98%. None of the following variables were significantly
different in patients with and without RLS: age, gender, age at onset of PD, duration of PD, Hoehn and Yahr stage, serum
ferritin level and dose and duration of dopaminergic medication. None of the patients who have had subthalamic nucleus deep
brain stimulation (n = 5) had RLS.

Conclusion: The prevalence of RLS in Thai PD patients was found to be much lower than in most of the previous studies,
especially those conducted in Europe and America.

Keywords: Parkinson’s disease, Restless legs syndrome