Fig. 1.

After enrollment and baseline evaluation, patients will be bilaterally implanted with DBS electrodes in the VIM and PSA. The electrodes are placed such that one contact is located on the intercommissural line (ICL), the neighboring ventral contact in the PSA, and the neighboring dorsal contact in the VIM. After implantation, the neutral contact on the ICL is activated until 3 months follow-up (3MFU). At 3MFU patients are randomized into a blinded crossover phase for 4 months (gray box). Depending on randomization, patients receive stimulation in the sequence PSA-VIM or VIM-PSA. Each phase of the crossover starts with a programming visit (PV) and ends with an evaluation visit (EV). After the blinded crossover phase, the stimulation contacts can be freely chosen until 12MFU