Staged Bilateral Exablate Treatment of Medication Refractory Essential Tremor
Staged Bilateral Exablate Treatment of Medication Refractory Essential Tremor
The objective of this prospective, multi-site, single-arm, open-label study is to capture the
 safety and efficacy (outcome) of bilateral staged Exablate treatment in subjects with
 bilateral medication-refractory essential tremor (ET). The staged second procedure will be
 performed at least 9 months after the first side. The benefit of real-time feedback will
 allow the physician to maximize benefit without jeopardizing safety.

 This study is designed as a prospective, open-label, single arm, multi-site study design.
Inclusion Criteria:

 1. Subjects who:

 1. previously underwent Exablate thalamotomy for their essential tremor in a
 clinical study or in a commercial procedure at least 9 months prior to enrolling
 in this study for contralateral Exablate thalamotomy

 2. Subjects who would benefit from a bilateral treatment for their essential tremor
 and would want to undergo a staged bilateral thalamotomy

 2. All subjects must have a complete baseline CRST prior from first Exablate thalamotomy

 3. Men and women age 22 years to 75 years of age.

 4. Minimum score of 24 on MoCA or 20 on MMSE

 5. Subjects who are able and willing to give consent and able to attend all study visits

 6. Postural or intention tremor severity score of greater than or equal to 2 in the both
 upper extremities as measured by the CRST rating scale while on stable medication

 7. Thalamus can be targeted by the Exablate device. The region must be apparent on MRI
 such that targeting can be performed.

 8. Able to communicate sensations during the Exablate Thalamotomy treatment

 9. Original (before first Exablate procedure) CRST score of 2 or above in any one of the
 items 16-23 from the Disability subsection of the CRST: speaking, feeding other than
 liquids, bringing liquids to mouth, hygiene, dressing, writing, working, and social
 activities.

 10. Subjects on antidepressant medications must be stable for at least 3 months prior to
 procedure(i.e., no change in medication drug or dosage for 3 months based on
 historical medical records).

 11. Remains eligible for Exablate treatment with no changes to medical history that would
 affect Exablate treatment criteria, (e.g., bleeding/coagulation requirements, or new
 pathology such as infarct, tumor, etc).

 Exclusion Criteria:

 1. Subjects with unstable cardiac status

 2. Subjects exhibiting any behavior(s) consistent with ethanol or substance abuse as
 defined by the criteria outlined in the DSM-IV as manifested by one (or more) of the
 following occurring within a 12 month period:

 3. Subjects with uncontrollable blood pressure (hypertensive with diastolic BP > 100 on
 medication)

 4. History of abnormal bleeding and/or coagulopathy, i.e. subjects with risk factors for
 intraoperative or postoperative bleeding as indicated by: platelet count less than
 100,000 per cubic millimeter, a documented clinical coagulopathy, or INR coagulation
 studies exceeding the institution's laboratory standard

 5. 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
 (e.g. Avastin) within one month of focused ultrasound procedure

 6. Active or suspected acute or chronic uncontrolled infection

 7. Individuals who are not able or willing to tolerate the required prolonged stationary
 supine position during treatment (can be up to 4 hrs of total table time.)

 8. Subjects with life-threatening systemic disease that include but not limited to the
 following will be excluded from the study participation: HIV, Liver Failure, blood
 dyscrasias, etc...

 9. Any clinically significant moderate to severe sensory deficit lasting greater than 30
 days after the first Exablate thalamotomy NOTE: Subjects with clinically significant
 moderate to severe sensory deficit following first Exablate thalamatomy should be
 excluded even if event resolves within a few months of treatment. This may cause new
 first thalamotomy subjects to be ineligible for the bilaterally staged treatment.

 10. Moderate to severe cerebellar disturbance (imbalance or ataxia) or presence of
 moderate or severe hemiparesis NOTE: Subjects with moderate to severe cerebellar
 disturbance (imbalance or ataxia) or presence of moderate or severe hemiparesis
 following first Exablate thalamatomy should be excluded even if event resolves within
 a few months of treatment. This may cause new first thalamotomy subjects to be
 ineligible for the bilaterally staged treatment.

 11. Any persistent dysphasia/dysarthria, language impairment following first Exablate
 thalamotomy.

 NOTE: Subjects with significant impairment following first Exablate thalamotomy should
 be excluded even if event resolves within a few months of treatment. This may cause
 new first thalamotomy subjects to be ineligible for the bilaterally staged treatment.

 12. Significant reduction in cognitive function since the first thalamotomy. NOTE:
 Subjects with significant reduction in cognitive function following first Exablate
 thalamatomy should also be excluded even if event resolves within a few months of
 treatment. This may cause new first thalamotomy subjects to be not eligible for the
 bilaterally staged treatment.

 13. Subject is pregnant or breastfeeding.

 14. Subjects who have an overall Skull Density Ratio of less than 0.40 as calculated at
 screening