An eligibility assessment for deep brain stimulation is performed in order to select patients who are likely to benefit from it. Parkinson's patients have to stop dopaminergic drugs the day before surgery. During the operation, the patient must remain awake for recording of neuronal activity and for test stimulations to optimize the position of the electrodes. Postoperatively, the stimulation is increased progressively in parallel with a decrease of dopaminergic treatments. After about ten days, the patient can return to home and controls continue as an outpatient. Three months postoperatively, a complete testing of the neurostimulator is performed and at the one year follow-up visit, the effectiveness of the DBS is assessed.