LFP Correlates of Movement Disorders

The Activa PC+S system will be implanted and programmed under the same clinical procedures
and standard of care as the Activa PC system. After implantation and standard clinical
programming, participants in our research study will be asked to return for additional
research visits where the recording sub-circuit of the device will be activated and local
field potentials (LFP) will be recorded in the device and transmitted through telemetry to a
base station for storage and future analysis. The sensing, or recording, sub-circuit will be
disabled, non-invasively, at the end of each research visit to minimize impact to battery
life of the device.

Inclusion Criteria:

- Potential participants must be undergoing DBS lead placement for Parkinson's Disease
that requires them to be awake during microelectrode recording.

- Potential participants have been treated with levodopa/carbidopa, and with a dopamine
agonist, at the maximal tolerated doses as determined by a movement disorders
neurologist.

- Potential participants must have a Hoehn and Yahr stage >= 2 in the medications OFF
state.

- Potential participants must have documented improvement in motor signs on versus off
dopaminergic medication, with a change in the Unified Parkinson's Disease Rating
Scale motor (UPDRS III) score of >= 30% off to on medication. Patients with tremor
predominant form of PD, quantified as a UPDRS tremor score in any one limb greater
than or equal to 3 and UPDRS sum of axial score (speech, posture, gait, balance) less
than or equal to 5, who do not reach the 30% threshold, may be included.

- Potential participants must have evidence of complications of medication, e.g.,
wearing off signs, fluctuating responses and/or dyskinesias, and/or medication
refractory tremor, and/or impairment in the quality of life on or off medication.

- Potential participants must have the ability to understand instructions in English.

- Potential participants are males or females between the ages of 21 and 75.

Exclusion Criteria:

- Individuals who are pregnant, breastfeeding, or are capable of becoming pregnant and
not using an acceptable method of birth control. Acceptable methods of birth control
include hormonal contraceptives, intrauterine device, abstinence or spermicide and
barrier.

- Individuals who have magnetic resonance imaging (MRI) scans demonstrating cortical
atrophy out of proportion to age.

- Individuals who have MRI scans showing focal brain lesions that could indicate a
nonidiopathic movement disorder.

- Individuals who have major comorbidity increasing the risk of surgery such as prior
stroke, severe hypertension, severe diabetes, or need for chronic anticoagulation
other than aspirin.

- Individuals who have had any prior intracranial surgery.

- Individuals who have clinically active depression defined according to the Diagnostic
and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria and
scored on a validated depression assessment scale.

- Individuals who have significant cognitive impairment and/or dementia as determined
by a standardized neuropsychological battery.

- Individuals who have a history of seizures.

- Individuals who are immunocompromised.

- Individuals who have an active infection.

- Individuals who require diathermy, electroconvulsive therapy (ECT) or transcranial
magnetic stimulation (TMS) to treat a chronic condition.

- Individuals who have an implanted electronic device such as a neurostimulator,
cardiac pacemaker or medication pump.

- Individuals who, at the discretion of the research team member, lack the cognitive
ability to understand the instructions and fully participate in research tasks.

- Unable to understand written and spoken instructions in English. Individuals who
carry a concomitant diagnosis that would preclude them from fully participating in
the research tasks due to difficulties associated with comprehending instructions,
cooperating with research tasks, or otherwise rendering the individuals incapable of
participating in the research tasks. Examples could include a visual or hearing
impairment preventing the individual from viewing a computer screen or hearing
instructions.