Our project is based on the fundamental hypothesis that epidural spinal cord stimulation (SCS) improves Freezing of gait (FOG) in patients with Parkinson's disease. In eight patients implantation of electrodes for SCS at the epidural thoracic level will be performed under general anaesthesia.

Evaluation of gait and motor symptoms will be performed with and without stimulation, after a 3-month period for each of the stimulation conditions.This is a pilot, single centre, prospective, randomized, double blinded, cross-over study.

Patients will be selected in the Movement Disorders Unit, Department of Neurology, University Hospital Grenoble. A preoperative assessment with gait assessment, clinical evaluation and Non-Motor Symptoms assessment will be realized. The implantation of electrodes for SCS at the epidural thoracic level connected to a neurostimulator at the abdominal level will be performed under general anaesthesia. During the first postoperative month, the optimization of SCS parameters will be performed by an experienced movement disorders neurologist.After the first post-operative month the patient will be randomized to the STIM ON condition (stimulation on, with the most effective parameters) or STIM OFF (without stimulation). The randomization will be performed in a double blinded fashion, by a neurologist working in open and not participating in the evaluations. After 3 months, the patient will be evaluated in a double blind condition, and the stimulation condition will be crossed for another period of 3 months. At the end of this second 3-month period, the patient will be again double-blind assessed. After this evaluation, the patient will enter the open phase of the study for a period of 6 months. For this last phase of the study, under STIM ON condition, an optimization of the stimulation settings will be realized, if necessary. At the end of this 6-month period of stimulation, the patient will be evaluated one last time. At all visits, clinical and gait evaluations will be carried out under chronic dopaminergic treatment. No change in antiparkinsonian treatment will be allowed during the entire study. Gait and clinical assessment will be performed at baseline and at the end of each double blinded phase and at 1-year follow-up. For the double-blind study the patient, the neurologist who performs the clinical evaluation and the expert who performs the gait test and analysis will be blind to the stimulation condition.

Inclusion criteria:

1. Patients with diagnosis of idiopathic PD
2. Aged 50-85 years
3. Having a FOG (score> 14 at New-FOG-Questionnaire; score> = 1 at item 2.13 of the Movement Disorders Society-Unified Parkinson's Disease Rating Scale) despite the optimization of medical treatment
4. Drug treatment stable for at least 2 months
5. Able to give written consent.

Exclusion criteria:

1. Pain syndrome (score> = 2 at item 1.9 of the MDS-UPDRS II)
2. Psychosis
3. Severe depression
4. Severe cognitive impairment (Mini Mental Score Examination <19)
5. Patient receiving STN DBS treatment
6. Presence of other neurological or medical pathologies interfering with walking
7. Subject in period of exclusion from another study
8. Subject under administrative or judicial supervision
9. Subject who cannot be contacted in an emergency.
10. Person with any administrative or judicial measure of deprivation of rights and liberty