The purpose of the STIMO-PARKINSON study is to evaluate the safety and preliminary efficacy of Targeted Epidural Spinal Stimulation (TESS) system to induce modulation in leg muscle recruitment in patients with advanced Parkinson's disease, and its capacity to improve key gait and balance deficits when employed in the context of a rehabilitation process of 3 to 5 months.

The study intervention consists of 7 phases preceded by pre-screening:

• enrolment and eligibility
• baseline
• surgery
• main phase of the study
• home-use
• end of main study phase
• (optional and conditional): 3 years follow-up

At baseline, general information and Parkinson related medical history are collected. Clinical evaluations are also completed without and with current therapy, (i.e. NO(MED+DBS), and MED+DBS conditions). Finally, quality of life questionnaires are collected for the patient as well as expectations questionnaires for the physiotherapists involved in the study.

The main phase of the study consists of:

• Stimulation configuration sessions during which TESS protocols will be setup and optimized. This procedure aims to configure the spatial and temporal parameters of TESS that will recruit specific muscle groups. Specific TESS protocols will be configured for various motor tasks which will be used during the rehabilitation phase and clinical evaluations.

• TESS-supported rehabilitation sessions during which patients will undergo an in-clinic rehabilitation training regime supported by TESS.

• Evaluation sessions during which four clinical evaluation sessions will take place focusing on assessment of locomotion, balance and PD related deficits. The tests will be done when patients are:

  (i) in NO(MED+DBS) condition (without any therapy, i.e. without medication and DBS OFF) (ii) in MED+DBS condition (the patient's standard therapeutical condition, i.e. usual medication dose and DBS ON) (iii) in TESS+MED condition (usual medication dose, TESS ON, DBS OFF) (iv) in TESS+MED+DBS condition (usual medication dose, TESS ON, DBS ON)

Participants are allowed to use the investigational system independently if deemed safe and beneficial as assessed by the Principal Investigator (Home-Use Phase).

One year after patient enrolment, the patient will come for follow up visits where he will again perform an evaluation session for each therapy condition as described above, to evaluate the long-term evolution.

If the therapy has been safe and beneficial, they can extend their study participation by entering the Follow-Up period of 3 years.

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