Parkinson Disease (PD) patients experience a variety of motor issues such as walking difficulties, loss of balance, and freezing while walking, which impacts their quality of life. Some symptoms, like freezing of gait (FOG), do not respond to medications typically used to treat PD. Current surgical procedures used to alleviate PD symptoms also do not always improve FOG. Since many traditional therapies have failed for the treatment of FOG, researchers have proposed the use of newer treatments. Recent research in animal models and clinical human data using SCS has produced promising results, specifically showing improvement in FOG with the use of SCS in patients with PD.

The purpose of this study is to evaluate the effectiveness of spinal cord stimulation (SCS) for the management of freezing of gait (FOG) that does not respond to conventional treatments in subjects with Parkinson's disease (PD). The investigators hypothesize that SCS significantly decreases FOG episodes in patients with PD.

1. Assess the safety, tolerability and preliminary evidence of effectiveness of upper thoracic spinal cord stimulation for freezing of gait in Parkinson's (PD) patients.
2. Explore the effects of two SCS programming paradigms on motor, nonmotor and quality of life measures in PD patients with freezing of gait.

Freezing of gait (FOG) is a devastating motor phenomenon which may occur in patients with Parkinson's Disease (PD) and other neurodegenerative disorders. It is characterized by episodes during which patients cannot generate effective forward stepping movements in the absence of motor deficits.

FOG leads to reduced mobility, loss of independence, social embarrassment, and caregiver stress. While most motor features of PD respond robustly to dopaminergic agents and deep brain stimulation (DBS), there are currently no effective treatments for FOG.

Indirect evidence from case reports of PD patients undergoing spinal cord stimulation (SCS) for neuropathic pain, has consistently described a positive effect of SCS on FOG. In addition, two recent reports demonstrated that thoracic SCS improved locomotion and FOG in patients with advanced PD. The promising role of SCS for the treatment of FOG in PD has encouraged us to assemble a multi-disciplinary team for the systematic investigation of the motor effects of SCS on FOG, locomotion and other parkinsonian features.

The current study integrates minimally invasive SCS and the use of robotic technology to determine objective gait parameters. The investigators propose a pilot study for the implantation of SCS to the spinal cord on PD patients with treatment-refractory FOG, including a longitudinal assessment of motor outcomes. Motors assessments will include: PAMSys and LEGSys to characterize gait, ActivePERS motion sensor to monitor ambulation parameters and overall activity at home, participants will also be given electronic tablets for the ActivePERS to collect real time information about falls.

Inclusion Criteria:

• Males and females between older than 18 years of age.
• Able to provide informed consent
• Diagnosed with idiopathic PD (meeting at least two of the three United Kingdom (UK) Brain Bank criteria for PD, specifically bradykinesia plus resting tremor or rigidity) whose major complaints is levodopa refractory FOG. Levodopa refractoriness will be defined as lack of subjective improvement on FOG episodes as reported by the patient.
• Documented dopaminergic response
• Optimized PD treatment including dopaminergic medications, and/or deep brain stimulation (DBS) therapy
• Presence of at least two self-reported levodopa refractory episodes of FOG per day, not limited to start hesitation
• At least one witnessed freezing event during the screening visit in the 'on' medication state (defined as 45 minutes after a regular dose of Levodopa for the subject being studied)

Exclusion Criteria:

Presence of any co-morbid psychiatric illness(es) that would interfere with the completion of the study or pose risk to the patient, as defined below:

• Presence of psychosis

• Depression BDI >14

• Anxiety BAI >14

  • Presence of an active infection, uncontrolled diabetes mellitus, immunosuppression or other medical contraindications to undergoing SCS implantation
  • Patients who are currently on anticoagulation treatment or unable to hold off the anticoagulants (including Plavix, Aspirin, Warfarin, etc.) 7 days prior to the SCS procedure.
  • Moderate Cognitive Impairment defined by a MoCA < 23
  • Diagnosis of failed back surgery syndrome, Complex Regional Pain Syndrome (CRPS) or intractable low back pain and leg pain.
  • Women of childbearing potential will be excluded as from participation due to the limited safety data of thoracic SCS on the fetus.