MRgFUS Pallidotomy for the Treatment of Task Specific Focal Hand Dystonia (TSFD)

The purpose of this study is to assess the safety and effectiveness of MRI-guided focused ultrasound (MRgFUS) for treating task specific focal hand dystonias (TSFD). TSFD refers to a condition where certain movements or tasks trigger involuntary muscle contractions, particularly during specialized and repetitive activities like writing (known as writer's dystonia), typing (typist's dystonia), playing musical instruments (musician's dystonia), or engaging in sports like golf, table tennis, or juggling. While TSFD affects around 1.2-1.5% of the general population, it's more common among athletes and musicians. Writer's dystonia, for example, typically starts with difficulty writing and hand cramping in the dominant hand, possibly spreading to the arm and shoulder muscles over time. In severe cases, the other hand may also be affected. Similarly, typist's dystonia can lead to finger flexion or extension issues during typing. Musician's dystonia is another form, seen in guitarists, pianists, harpists, or flute players, often emerging during the peak of their careers and significantly impacting musical performance. These dystonias can be career-ending as they impair performance and rarely go into remission, with onset often occurring around the age of forty.

Surgical treatments for Task-Specific Focal Dystonia (TSFD) are less often explored than for other dystonias. Thalamotomy, targeting the ventro-oralis (Vo) nucleus, has shown some promise for hand dystonias like writer's cramp or musician's dystonia. Anecdotally, some benefit from deep brain stimulation (DBS) targeting the globus pallidus internus (GPi) has also been shown, but large-scale studies for TSFD are lacking.

Another promising approach is MR guided focused ultrasound thalamotomy, a non-invasive procedure that uses real-time imaging to precisely target brain areas. This method has already shown success in treating essential tremors and Parkinson's disease symptoms. Recent studies and anecdotal cases have also demonstrated its potential for treating TSFD, with improvements in symptoms observed in patients with writer's cramp, musician's dystonia, and other related conditions.

The Exablate MR Guided Focused Ultrasound Transcranial system is a device designed to overcome the limitations of delivering ultrasound through the intact skull. It uses advanced technology like water-cooling, acoustic correction algorithms, and patient-specific CT data to ensure precise and safe delivery of ultrasound energy to targeted brain areas. This pilot study protocol aims to utilize MR guided focused ultrasound thalamotomy as a treatment option for TSFD.

Inclusion criteria

• Clinical diagnosis of moderate to severe TSFD with impact in their daily function or occupation function
• Patients who failed to response or had unsatisfactory response to the first treatment, such as Botulinum toxin treatment or DBS or refuse these alternative options
• Age greater than 21 and less than 75 years
• Subjects who are able and willing to give consent and able to attend all study visits,
• Documented chronic, symptoms for more than 6 months duration
• Pallidotomy is feasible based on evaluation of imaging studies
• Patient able to communicate sensations during the ExAblate TcMRgFUS treatment
• Two members of the medical team have agreed upon inclusion and exclusion criteria

Exclusion criteria

• Patient with contraindications to MRI such as severe claustrophobia and metallic implants incompatible with MRI.
• Presence of generalized dystonia or involvement of two or more contiguous body regions (such as Arm along with neck)
• Severe psychiatric disorder such as uncontrolled depression, anxiety, bipolar disorder, prior attempt at suicide or suicide ideation in preceding 12 months
• Life expectancy less than 12 months
• Anticoagulant or antiplatelet medications as well as underlying coagulopathy
• Pregnant ladies or women of childbearing age who are sexually active and not using contraception
• Inability to provide informed consent, for example due to underlying cognitive impairment or aphasia
• Presence of intracranial mass or an acute intracranial abnormality
• Subjects with unstable cardiac status such as unstable angina pectoris, documented myocardial infarction within 6 months of protocol entry or ejection fraction less than 40
• Subjects exhibiting any behavior(s) consistent with ethanol or substance abuse as defined by the criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders(DSM-IV)
• Severe hypertension (diastolic blood pressure > 100 on medication or persistently elevated systolic blood pressure>140 mmHg despite adequate antihypertensive medications)
• History of intracranial hemorrhage, traumatic brain injury or thalamic stroke.
• Cerebrovascular disease (multiple cerebrovascular accident's (CVA) or CVA within 6 months)
• Subjects with life-threatening systemic disease that include and not limited to the following will be excluded from the study participation: HIV, Liver Failure, blood dyscrasias, etc.
• Subjects with a history of seizures within the past year
• Individuals who are not able or willing to tolerate the required prolonged stationary supine position during treatment (can be up to 4 hours of total table time.)

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