The prevalence of restless legs syndrome in Thai patients with parkingson's disease and patients taking neuroleptic drugs

Abstract

Background: Restless legs syndrome (RLS) is a common neurologic disorder which is underdiagnosed in all parts of the world in spite of being treatable. The symptoms of RLS are very responsive to dopaminergic medications even at a very low dose. There have been several studies looking at the prevalence of RLS in Parkinson’s disease (PD) patients in other countries and no study in patients taking neuroleptic drugs from any cause – both being conditions of CNS dopamine deficiency. Objectives: To study the prevalence of RLS in Thai PD patients and Thai patients taking neuroleptic drugs. Methods: PD patients were consecutively interviewed from movement disorders clinic for RLS symptoms and patients taking neuroleptic drugs were consecutively interviewed from psychiatry clinic of Chulalongkorn Hospital. Diagnosis of RLS was made according to the NIH-IRLSSG diagnostic criteria. Serum ferritin level was checked in patients with and without RLS. Patients with end-stage renal disease, peripheral neuropathy, spinal cord diseases and malignancy were excluded from the study. Results: For PD patients, 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%. For patients taking neuroleptic drugs, only one out of 100 patients had symptoms consistent with RLS (1%). She was a 40 year old female with a diagnosis of depression. She started having RLS symptoms approximately four years after starting perphenazine. The symptoms persisted after the medications were discontinued though they decreased in frequency and severity. Conclusions: 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. The prevalence of RLS in patients taking neuroleptics is also low. Other factors apart from dopaminergic dysfunction are likely to be involved in the pathogenesis of RLS