Spinal Cord Stimulation (SCS) for Freezing of Gait (FOG) in Parkinson's Disease

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.

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 signs or symptoms suggestive of atypical or secondary parkinsonian
syndromes, such as multiple systems atrophy (MSA), progressive supranuclear palsy
(PSP), corticobasal ganglionic degeneration, vascular or postencephalitic
parkinsonism:

- Early severe autonomic (within the first two years of symptom onset)

- Downward vertical supranuclear gaze palsy

- Early bulbar dysfunction (within the first two years of symptom onset)

- Unequivocal cerebellar abnormalities and/or cortical sensory loss

- Evidence of an alternative condition known to produce parkinsonism and plausibly
connected to patient's symptoms

- Presence of any co-morbid psychiatric illness(es) that would interfere with the
completion of the study or pose risk to the patient.

- Presence of an active infection, uncontrolled diabetes mellitus, immunosuppression or
other medical contraindications to undergoing SCS implantation

- Patients who are currently taking anticoagulants which would preclude the safe
implantation of the device.