Inclusion Criteria:  Idiopathic Parkinson's disease with III-IV Hoehn-Yahr stage, exhibiting severe gait difficulties and postural instability With Medtronic DBS implant and receiving medication for Parkinson's disease Aged 18 to 80 years Stable medical, physical and psychological condition as considered by the Investigators in accordance with treating physician and treating neurologist. Must agree to comply in good faith with all conditions of the study and to attend all required study training and visit Must provide and sign the study's Informed Consent prior to any study-related procedures  Exclusion Criteria:  Severe or chronic medical disorder pre-existing PD diagnosis affecting rehabilitation Active oncological disease requiring heavy treatments and frequent MRI controls Having an implanted device that is active (e.g., pacemaker, implantable cardiac defibrillator) whose interference with the investigational system's neurostimulator (Activa RC) is not confirmed safe by the CE-mark of the device, or having an indication that might lead to implantation of such device Inability to follow study procedures, e.g. due to language problems, psychological disorders, dementia as considered by the Investigators in accordance with treating physician and treating neurologist Hematological disorders with an increased risk of hemorrhagic event during surgical interventions Life expectancy of less than 12 months Pregnant or breast feeding Participation in another interventional study