ExAblate Transcranial MR Guided Focused Ultrasound for the Treatment of Essential Tremors

A Pivotal Study to Evaluate the Effectiveness and Safety of ExAblate Transcranial MRgFUS Thalamotomy Treatment of Medication Refractory Essential Tremor Subjects

The objective of this prospective, randomized, double-blind (to subjects, local site's blinded assessor and Tremor Core Lab assessors), crossover, multi-site, two-arm study (ExAblate treated arm Vs ExAblate Sham treated control arm) is to test the efficacy of treatment using the ExAblate Transcranial System and to further demonstrate safety in medication-refractory tremor in subjects with essential tremor (ET).

This study is evaluating a new technique for performing Thalamotomy for tremor control. While current techniques have possible invasive or radiation effects, the use of ExAblate if totally non-invasive and without any radiation. After informed consent and screening, eligible subjects will be randomized to either an ExAblate treatment or an ExAblate Sham or "fake" procedure. The chance of randomization to Sham is one out of four. Subjects who are randomized to Sham Control will undergo the same procedure and follow-up visits through their Month 3 visit. After the Month 3 assessments are complete, all subjects will be unblinded and those in the Sham treated group will have the option for an actual ExAblate treatment in an unblinded fashion, as long as they still qualify for ExAblate treatment. All subjects will be followed at 6 and 12 months and for up to 5 years as directed by their doctor.

Inclusion Criteria:

• Men and women, age 22 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 Essential Tremor as confirmed from clinical history and examination by a neurologist or neurosurgeon specialized in movement disorder
• Subject exhibits a significant disability from their ET despite medical treatment
• Subjects should be on a stable dose of all ET 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
• 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