ExAblate Transcranial MR Guided Focused Ultrasound for the Treatment of Parkinson's Disease

This is a feasibility study to evaluate the safety and initial effectiveness of unilateral ExAblate thermal ablation of the Vim thalamic nucleus of subjects suffering from medication-refractory, idiopathic, tremor-dominant PD, using the ExAblate Transcranial system compared to a Sham Vim thalamotomy procedure.

Data will be collected to establish the basic safety of this type of treatment as the basis for later studies that will evaluate its full clinical efficacy. The Sham treatment data will be used to evaluate placebo effect from treatment.

Subjects who sign informed consent and pass all eligibility criteria will be randomized to a treatment assignment. During treatment, the assigned treatment (ExAblate Transcranial or Sham ExAblate Transcranial)will be delivered. Subjects are followed in a blinded fashion for three (3) months. After the 3-month assessment, subjects will be unblinded and told their treatment assignment. Subjects receiving Sham ExAblate Transcranial treatment who still meet criteria will be crossed over and receive an active ExAblate Transcranial treatment. Subjects will be followed for up to two (2) years. Follow-up at 1 week, 1 month, 3 months, 6 months, 9 months, 12 months and up to two (2) years includes Unified Parkinson's Disease Rating Scale (UPDRS) scoring, mental and cognitive functional testing and questionnaires.

Eligibility Criteria:
Inclusion Criteria:

* Men and women, age 30 years and older
* Subjects who are able and willing to give informed consent and able to attend all study visits
* Subjects with a diagnosis of idiopathic PD as confirmed from clinical history and examination by a movement disorder neurologist at the site
* Subject demonstrates a severe resting tremor or postural/action as measured by UPDRS
* Subject exhibits a significant disability from their PD tremor despite medical treatment
* Subjects should be on a stable dose of all PD medications for 30 days prior to study entry
* Subject is able to communicate sensations during the ExAblate Transcranial procedure

Exclusion Criteria:

* Subjects with unstable cardiac status
* Subjects exhibiting any behavior(s) consistent with ethanol or substance abuse
* Severe hypertension
* Subjects with standard contraindications for MR imaging such as non-MRI compatible implanted metallic devices including cardiac pacemakers, size limitations, etc.
* Known intolerance or allergies to the MRI contrast agent including advanced kidney disease or severely impaired renal function
* Significant claustrophobia that cannot be managed with mild medication
* Current medical condition resulting in abnormal bleeding and/or coagulopathy
* Receiving anticoagulant (e.g. warfarin) or antiplatelet (e.g. aspirin) therapy within one week of focused ultrasound procedure or drugs known to increase risk or hemorrhage
* History of intracranial hemorrhage
* History of multiple strokes, or a stroke within past 6 months
* Subjects who are not able or willing to tolerate the required prolonged stationary supine position during treatment
* Are participating or have participated in another clinical trial in the last 30 days
* Subjects unable to communicate with the investigator and staff
* Subjects with a history of seizures within the past year
* Subjects with brain tumors
* Subjects with intracranial aneurysms requiring treatment or arterial venous malformations (AVMs) requiring treatment
* Subjects who have had deep brain stimulation or a prior stereotactic ablation of the basal ganglia