[Effect of high dose pergolide mesilate on restless legs syndrome associated with Parkinson disease]

Restless legs syndrome (RLS) is one of the common nocturnal disturbance seen in Parkinson's disease (PD) patients. The prevalence of RLS with PD is greater than that of general populations; however, etiology of RLS in patients with PD is still controversial. We report a 63-year-old man with PD, who was admitted to our hospital with uncontrollable unpleasant feeling in both legs leading to sleep disturbance. At age 59, he experienced numbness and nocturnal myoclonus in his right foot. One year later, he developed resting tremor and bradykinesia in his right hand, and was diagnosed as PD. Levodopa was initiated with favorable response for his resting tremor and bradykinesia, however, his dysesthesia of the legs spread to both side and associated with an urge to move which occurs at rest and was ameliorated by walking. On admission, his parkinsonism was well controlled by 400 mg/ day of levodopa/benserazide. Polysomnography (PSG) revealed periodic limb movements in sleep (PLMS). Secondary RLS such as drug-induced, iron deficiency and uraemia, was excluded in this patient. Because levodopa did not improve his RLS, additional symptomatic RLS treatment was initiated. Oral dosage with 150 microg pergolide did not have any effect on his RLS symptoms. An increase up to 750 microg pergolide led to a marked reduction of symptoms. Repeated PSG showed significant reduction of PLMS and improved sleep efficacy. Usually, low dose of dopamine agonist is enough to treat RLS occurred in general populations. However, moderate to high dose of dopamine agonists were needed for our patient with RLS, indicating that pharmacological responses might be different between RLS in general and that associated with PD. It is important to consider that PD-related RLS can be treated with high dose dopamine agonist to obtain favorable management of nocturnal disturbances.