Exploit the Neural Source and the Feasibility of Transcranial Direct Current Stimulation for Freezing of Gait in Parkinson's Disease and Multiple System Atrophy

Exploit the Neural Source and the Feasibility of Transcranial Direct Current Stimulation for Freezing of Gait in Parkinson's Disease and Multiple System Atrophy

In this project, the investigators will deliver a 5-day session of transcranial direct current stimulation (tDCS) to the leg motor cortex of the FOG patients to examine whether the intervention will benefit the patients in a double blind randomized design. Six assessments with different combinations of clinical scaling, gait analysis, electrophysiological investigation and fMRI examinations before and after tDCS will be conducted. The treatment and placebo groups will be crossed over after one-month washout. The investigators will investigate whether the possible tDCS beneficial effect will be different or similar in patients with different electric sources. In addition, how long the possible beneficial effect of tDCS can be consolidated after the 5-day course of stimulation is also crucial. The investigators aim to peep the myth of FOG in PD and MSA by the multi-modality approach and hope the study will benefit the long suffering patients.

Inclusion Criteria:

1. Patients meet the diagnosis of PD41 or MSA43 based on the established consensus criteria
2. Age above 30 years old and below 85 years

Exclusion Criteria:

1. Impairment of cognition that leads unable to fully cooperate with the oral commands during examinations
2. Functional III or above congestive heart failure, or cancer with distant metastasis
3. Hoehn and Yahr stage 5 in PD or MSA