Testing spinal stimulation for walking difficulties

Inclusion Criteria: * Typical form of Parkinson's Disease with II-IV Hoehn-Yahr stage with standard therapy, * Suffering from debilitating locomotor deficits, including gait impairments of either postural instability and/or freezing of gait, despite optimal medical management, * 18 years of age or older, * Able to understand and interact with the study team in French or English, * Must use safe contraception for women of childbearing capacity, * Must agree to comply in good faith with all conditions of the study and to attend all required study trainings and visits. * Must provide and sign the study's Informed Consent prior to any study-related procedures. Exclusion Criteria: * Atypical forms of Parkinson's Disease (such as Multiple System Atrophy or Progressive Supranuclear Palsy), * Secondary causes of gait problems independent of Parkinson's Disease, * Inability to follow study procedures, * Unstable or significant medical condition that is likely to interfere with study procedures or likely to confound study endpoint evaluations as determined by the Investigator, * History of major psychiatric disorders or major neurocognitive disorder as considered by the Investigators in accordance with treating physician and treating neurologist, * Major change in PD treatment planned until the end of the main study phase (such as Deep Brain Stimulation or dopamine-pump implantation), * Diseases and conditions that would increase the morbidity and mortality of the implantation surgery, * Spinal anatomical abnormalities precluding surgery, * History of drug or alcohol abuse in the past 5 years, * Life expectancy of less than 12 months, * Pregnant or breast feeding, * Intention to get pregnant during the course of the study, * Indication requiring frequent Magnetic Resonance Imaging (MRI), * Experimental treatment taken in the past 5 years, * Participation in another interventional study, * Enrolment of the investigator, his/her family members, employees, and other dependent persons.