TDCS for Parkinsońs disease-related pain: a randomized trial

Objective To evaluate the effects of transcranial direct current stimulation (tDCS) on Parkinson’s disease (PD)-related pain. Methods This triple-blind randomized controlled trial included twenty-two patients (age range 38-85, 10 male) with PD-related pain. Eleven subjects received ten sessions of 20 minutes tDCS over the primary motor cortex contralateral to pain at 2 mA intensity. Eleven subjects received sham stimulation. Outcome measures included changes in the Kinǵs Parkinsońs Pain Scale (KPPS), Brief Pain Inventory (BPI), widespread mechanical hyperalgesia (WMH), temporal summation of pain (TS), and conditioned pain modulation (CPM). Results Significant differences were found in KPPS between groups favoring the active-tDCS group compared to the sham-tDCS group at 15-days follow-up (p=0.014) but not at 2 days post-intervention (p=0.059). The active-group showed significant improvements over the sham-group after 15 days (p=0.017). Significant changes were found in CPM between groups in favor of active-tDCS group at 2 days post-intervention (p=0.002) and at 15 days (p=0.017). No meaningful differences were observed in BPI or TS. Conclusions tDCS of the primary motor cortex alleviates perceived PD-related pain, reduces pain sensitization, and enhances descending pain inhibition. Significance This is the first study to test and demonstrate the use of tDCS for improving PD-related pain.