Non-Invasive Brain Stimulation for the Treatment of Parkinson´s Disease-related Pain

The Starstim tDCS® stimulator will be used by an experienced physical therapist to transfer direct current by a saline-soak pair of surface sponge electrodes (35cm2). The anode electrode will be placed over C3 (EEG 10/20 system) and the cathode electrode over the contralateral supraorbital area (Fp2), in order to enhance the excitability of M1 (32). Regarding the stimulated hemisphere, contralateral M1 will be stimulated in patients with asymmetric pain and the dominant (contrary to the dominant hand determined by the Edinburgh Handedness Inventory) in patients with symmetric pain, due to the widespread changes induced by tDCS in other cortical areas, including contralateral M1. A constant current of 2 milli amps intensity (subthreshold intensity) will be applied for 20 min, with 30 seconds of ramp-up and 30 seconds of ramp-down.

The electrodes will be placed in the same positions as for M1 stimulation, but only applying ramping active current for 30 seconds in the beginning and at the end of the procedure for a reliable blinding.