 The purpose of this study is to investigate the effect of dopaminergic medication ropinirole hydrochloride, Requip on relieving the symptoms of ULD patients. Patients will undergo sixteen weeks intervention period. The main efficacy determinants are changes in unified myoclonus rating scale UMRS, nerve conduction, multi-modality evoked potentials including visual evoked potential VEP, somatosensory evoked potential SSEP and brainstem auditory evoked potential BAEP, blink reflex habituation and electroencephalography EEG. Tolerability and the safety of the medication are determined. The study setting is placebo controlled, crossover, two-group and double blind study. 