I. Disclaimer

This document is intended to be used as a reference for non-VA providers and is not intended to replace clinical judgment when determining care pathways. These guidelines do not guarantee benefits or constitute medical advice.

II. Clinical Determinations and Indications

1. Indications for Magnetic Resonance-Guided Focused Ultrasound Thalamotomy
   Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy is indicated for the following: 
   • Idiopathic essential tremor with medication-refractory tremor
   • Tremor-dominant Parkinson’s disease with medication-refractory tremor
2. It may be considered medically necessary/covered when ALL the following criteria are met:
   • Diagnosis of ONE of the following medical conditions:
     • Idiopathic essential tremor with medication-refractory tremor 
       • The Veteran has had at least three trials of medical therapy, including at least one first-line agent (unless contraindicated) 
     • Tremor-dominant Parkinson’s disease with medication-refractory tremor 
       • Refractory (or intolerant) to levodopa or levodopa equivalent daily dosage greater than or equal to 1200 mg
   • Must meet ALL the following clinical criteria to allow for treatment of Veterans with mild but disabling tremor:
     • Tremor is disabling with a score greater than or equal to two on any of the eight items in the disability subsection of the Clinical Rating Scale for Tremor (CRST) or another nationally accepted clinical measure of tremor severity
     • Not a candidate for deep brain stimulation (DBS) due to comorbidities or patient refusal for DBS after informed consent including discussion of surgical process, device programming, and device maintenance
       • It is strongly recommended to have an evaluation from a movement disorder specialist (face-to-face, telemedicine, or via e-consult)
     • A skull density ratio of less than 0.40

2. Limitations/Exclusions
   Magnetic resonance-guided focused ultrasound thalamotomy is considered not medically necessary and not covered if any of the following are applicable:
   • Untreated coagulopathy
   • Severe cognitive impairment (score less than 24 on the Mini–Mental State Examination)
   • Existing DBS system, full or partial
   • Contraindications to magnetic resonance imaging (MRI) are present (e.g., metallic foreign body in eye, unable to lay flat for study, etc.)
   • History of contralateral thalamotomy less than nine months from the initial treatment
     • Note: Revision on the ipsilateral side may be indicated, subject to the treating physician’s clinical judgment
3. Conditions/indications for which MRgFUS thalamotomy is not medically necessary include, but are not limited to, the following:
   • Treatment of head or voice tremor
   • Performing bilateral thalamotomy in one procedure
     
4. For all other conditions or indications not listed in section II.a. of this document, MRgFUS thalamotomy is considered not medically necessary and not covered due to insufficient evidence of efficacy and safety.

3. Description of Treatment
   Magnetic resonance-guided focused ultrasound is an incisionless procedure that combines MRI to target and ultrasound to ablate tissue at the focal point that causes tremors without injuring surrounding structures. Real-time MRI allows visualization during the ablation process using thermographic imaging which allows precision control by continuously monitoring the tissue temperature. Magnetic resonance-guided focused ultrasound is an incisionless thermal ablation technique that avoids the need for open brain surgery. During the procedure, patients are awake to provide feedback, allowing for assessment of tremor reduction and potential occurrence of adverse effects.

Magnetic resonance-guided focused ultrasound for the treatment of medication-refractory tremors in idiopathic essential tremor and tremor-dominant Parkinson’s disease specifically targets the ventralis intermedius of the thalamus in the brain, an area that relays cerebello-motor information. Heat created from high intensity ultrasound beam technology targets specific areas of the thalamus, resulting in a tiny burn or lesion on the targeted spot responsible for the tremor. The goal is to ablate the tissue, interrupting the activity responsible for the tremor and relieve the associated symptoms.

III. Background and Supporting Information

The following information is for reference purposes only in accordance with the medical benefits package outlined in 38 C.F.R. § 17.38 (b). Each subsection supports VA’s determinations for medical necessity and alignment with generally accepted standards of medical practice.

1. Background Information
   Patients with medication-refractory tremors, due to essential tremor or tremor-dominant Parkinson’s disease, may be candidates for various treatment options. These include deep brain stimulation (DBS), radiofrequency ablation, and magnetic resonance-guided focused ultrasound (MRgFUS) ablation. The incisionless technique to ablate an intracranial target while the patient is awake has made MRgFUS a reasonable outpatient treatment option for patients who are not candidates for or have failed DBS. Patients that are not suitable to undergo a surgical procedure are potential candidates for MRgFUS thalamotomy for the treatment of medication-refractory tremors in idiopathic essential tremor and tremor-dominant Parkinson’s disease.
   
   Essential Tremor
   Essential tremor is a neurological (nervous system) disorder which causes involuntary shaking or trembling of parts of the body. Essential tremor may also be called benign essential tremor and is the most common type of tremor, which can occur at any age, but is most common in people who are 40 years and older. There is no known cause for essential tremor, but 50% of the cases are associated with a genetic risk factor. Studies suggest that the cerebellum, thalamus, and cortex (components of the brain structure) are involved in the mechanism of essential tremor. Symptoms may include a shaky/quivering voice, head nodding, and hand shaking impacting the ability to write, hold objects, or use tools. Symptoms may be triggered by certain medications, emotions, fatigue, caffeine, or temperature changes.
   
   Essential tremor is not a life-threatening condition and does not decrease life expectancy. Essential tremor can be severely debilitating, affecting the ability to manage emotions, work or social requirements, and activities of daily living. There is no known cure, but essential tremor may be managed with beta blockers, anticonvulsants, or surgery.
   
   Tremor-dominant Parkinson’s Disease
   Parkinson’s disease is a progressive neurodegenerative disorder defined by a constellation of cardinal features that include tremor, bradykinesia, rigidity, and postural instability. The spectrum of motor and non-motor manifestations of the disease is further expanding. Tremor is one of the most common motor symptoms of Parkinson’s disease and is reported to affect up to 75% of patients during their disease course. Both kinetic and re-emergent postural forms can also coexist, which may result in substantial functional impairment.
   
   Parkinson’s disease is recognized to be heterogeneous, and growing evidence of clinical subgroups has emerged based on the predominant symptom associated with each subtype. In comparison to other Parkinson’s disease subtypes, tremor-dominant Parkinson’s disease tends to have a slower disease progression, less debilitating non-motor symptoms, decreased probability of developing levodopa-induced dyskinesia, and potential resistance to dopaminergic agents.
   

2. Research, Clinical Trials, and Evidence Summaries
3. Magnetic Resonance-Guided Focused Ultrasound Thalamotomy for Medication-Refractory Essential Tremor

   Research evidence and clinical trials support MRgFUS as a safe and effective treatment option for medication-refractory essential tremor. Magnetic resonance-guided focused ultrasound has proven to be more effective than the sham procedure and a viable treatment option for patients who are not candidates for DBS. Magnetic resonance-guided focused ultrasound has proven to reduce tremor severity, improve quality of life, and increase the ability to perform activities of daily living.

   Cosgrove et al. (2022) evaluated the long-term safety and efficacy of unilateral MRgFUS thalamotomy for the treatment of medication-refractory essential tremor, from a cohort of patients in a multicenter clinical trial. The study used the Clinical Rating Scale for Tremor (CRST) to assess outcomes and results measured by a qualified neurologist. The team found that unilateral MRgFUS thalamotomy is an effective treatment for patients with medication-refractory essential tremor, and showed significant tremor improvement at five years with an overall improvement in quality of life without any progressive or delayed complications.

   Hand-tremor scores (based on CRST) showed greater improvement after focused ultrasound thalamotomy (from 18.1 points at baseline to 9.6 at three months) than after the sham procedure (from 16.0 to 15.8 points). The improvement in the thalamotomy group was maintained at 12 months. Secondary outcome measures assessing disability and quality of life also improved with active treatment (the blinded thalamotomy cohort) as compared with the sham procedure. Adverse events in the thalamotomy group included gait disturbance in 36% of patients and paresthesia or numbness in 38%, these adverse events persisted at 12 months in 9% and 14% of patients, respectively. Magnetic resonance-guided focused ultrasound thalamotomy reduced hand tremor in patients with essential tremor.

   In 2018, Ontario Health performed a systematic review of literature that examined MRgFUS neurosurgery alone compared to other interventions for the treatment of moderate-to-severe, medication-refractory essential tremor. Studies included in this review found MRgFUS neurosurgery had a favorable safety profile and should be considered a safe and effective option for moderate-to-severe, medication-refractory essential tremor. It provides a noninvasive option for all considering neurosurgery, including patients who are ineligible for invasive neurosurgery. Patients with essential tremor who had undergone MRgFUS neurosurgery reported a substantial reduction in tremor that resulted in an improvement in quality of life and the ability to perform activities of daily living.

   Chang et al. (2017) conducted a study reporting the results of MRgFUS thalamotomy for essential tremor at a two-year follow-up point. Seventy-six patients with moderate-to-severe essential tremor, who had not responded to at least two trials of medical therapy, were enrolled in the original randomized study of unilateral thalamotomy and evaluated using the CRST. Sixty-seven patients continued in the open-label extension phase of the study with monitoring for two years. Mean hand tremor score at baseline improved by 55% at six months. The improvement in tremor score from baseline was durable at both one and two years. The disability score at baseline improved by 64% at six months. This improvement was sustained at one and two years after the procedure. Paresthesias and gait disturbances were the most common adverse effects at one year, each observed in 10 patients with an additional five patients experiencing neurological adverse effects. None of the adverse events worsened over the follow-up period, and two resolved. There were no new delayed complications at two years. Tremor suppression after MRgFUS thalamotomy for essential tremor was maintained at two years. Latent or delayed complications did not develop after treatment.

   Kaplitt et al. (2024) conducted a multicenter, prospective, open-label clinical trial which evaluated the safety and efficacy of staged, bilateral MRgFUS thalamotomy in 51 patients with medication-refractory essential tremor who had previously undergone successful unilateral MRgFUS thalamotomy. The study measured tremor/motor scores, postural tremor, and functional disability using the CRST at baseline and at intervals up to 12 months post-treatment. Results showed a significant reduction in tremor/motor scores (mean reduction of 66% at three months, sustained at 12 months), postural tremor (81% reduction), and functional disability (73% improvement), with most adverse events (such as numbness, dysarthria, and ataxia) being mild and transient. The authors concluded that staged, bilateral MRgFUS thalamotomy is a safe and effective option for patients with bilateral essential tremor, with adverse events generally mild and resolving over time. They recommend considering staged bilateral treatment for patients with ongoing disability from contralateral tremor, noting that the evidence supports regulatory approval for this procedure.

   Magnetic Resonance-Guided Focused Ultrasound Thalamotomy for Medication-Refractory Tremor in Tremor-Dominant Parkinson’s Disease

   Research evidence and clinical trials support MRgFUS as a safe and effective treatment option for medication-refractory tremor in Parkinson’s disease. Magnetic resonance-guided focused ultrasound thalamotomy has proven to be more effective in treating medication-refractory tremor in tremor-dominant Parkinson’s disease than the sham procedure, and prevents the need to increase dopaminergic medications. Study results suggest conducting ongoing trials with larger cohorts to determine adverse events and long-term outcomes for the treatment of medication-refractory tremor in tremor-dominant Parkinson’s disease with MRgFUS.

   Abusrair et al. (2022) conducted a structured literature review to highlight recent advances in the underlying pathogenesis and treatment modalities for tremor in Parkinson’s disease. The purpose of the review was to highlight the underlying pathophysiological mechanisms of tremor in Parkinson’s disease and recent advances in therapeutic options. Tremor is one of the most common symptoms associated with Parkinson’s disease. The complexity of Parkinson’s disease tremor and the wide and unpredictable response to therapeutic modalities remain challenging. Poor response to dopaminergic agents is common, reflecting the role of multiple underlying pathophysiologic processes. Evidence for advanced modalities is heterogeneous, with no sufficient comparative studies to address their efficacy in this specific group of Parkinson’s disease patients. Despite promising results, authors suggested further investigation of long-term data for newer advanced modalities, such as MRgFUS, to ensure safety and sustained efficacy.

   Andreasi et al. (2022) performed a study of patients diagnosed with early-stage idiopathic Parkinson’s disease and tremor-dominant clinical phenotype who underwent MRgFUS ventralis intermedius nucleus (Vim) thalamotomy and patients treated with oral dopaminergic medications. A total of 145 patients with tremor-dominant Parkinson’s disease were initially evaluated. Ten patients in the MRgFUS group and 20 patients receiving oral dopamine therapy met selection criteria. The study set out to prove that MRgFUS Vim thalamotomy in early-stage tremor-dominant Parkinson’s disease prevented an increase in dopaminergic medications six months after treatment compared with matched Parkinson’s disease control subjects on standard medical therapy. Patients had at least one follow-up visit greater than or equal to six months after the procedure. Magnetic resonance-guided focused ultrasound thalamotomy, performed in patients with early-stage tremor-dominant Parkinson’s disease, allowed them to maintain a low daily dosage of oral dopaminergic medications along with a good control of tremor for at least six months. The procedure was found to have an acceptable safety profile in patients with tremor-dominant Parkinson’s disease presenting with unsatisfactory response to a therapeutic dose of pharmacological approaches. In patients with early-stage tremor-dominant Parkinson’s disease, MRgFUS thalamotomy may help decrease the tremor and avoid the need to increase dopaminergic medications. Authors concluded that MRgFUS thalamotomy is a safe and effective treatment for tremor in patients with Parkinson’s disease.

   Chua et al. (2023) evaluated the clinical outcomes of 48 patients with medically refractory tremor-dominant Parkinson’s disease who underwent MRgFUS thalamotomy and assessed tremor outcomes and adverse effects at various intervals. The team’s objective was to report the largest prospective experience of unilateral MRgFUS thalamotomy for the treatment of medically refractory tremor-dominant Parkinson’s disease. Results from the study found significant tremor control persisted at all follow-ups, which were statistically significant. The most commonly observed adverse events after MRgFUS thalamotomy were gait imbalance and sensory defects. Gait imbalance was reported at 59.18% on day one and decreased to 20% at two years. Sensory deficits were reported at 14.29% on day one and 13.64% at one year. Motor weakness, dysgeusia, and dysarthria were also noted in patients. The majority of adverse events improved over time, particularly after the three-month follow-up point. The team concluded that MRgFUS thalamotomy is an effective treatment for sustained tremor control in patients with medically refractory tremor-dominant Parkinson’s disease with a 78.6% reduction at one year.

   Bond et al. (2019) conducted a clinical trial designed to explore the safety and initial efficacy of unilateral MRgFUS for symptom management in patients with tremor-dominant Parkinson’s disease. Although it was a pilot study, it incorporated a randomized clinical trial design, controlled with sham procedures to account for placebo effects that often confound research on Parkinson’s disease treatments. Adult patients with idiopathic tremor-dominant Parkinson’s disease were included if the disease was deemed medication-refractory, severe, and disabling. Twenty patients were randomized to unilateral MRgFUS thalamotomy and seven to sham procedure. The clinical trial of unilateral MRgFUS thalamotomy for patients with tremor-dominant Parkinson’s disease demonstrated a 62% median improvement in contralateral hand tremor CRST sub-scores in the MRgFUS thalamotomy group. There was a 22% median improvement in the sham group. A notable placebo response was observed with the sham procedures, necessitating a larger study to prove efficacy. Adverse events were similar to other thalamotomy procedures and will likely improve as the technology for monitoring the MRgFUS thalamotomy procedure improves.

   Ge et al. (2021) conducted a database search of Medline, EMBASE, and the Cochrane Library for eligible randomized controlled trials comparing a magnetic resonance-guided focused group, versus a sham procedure group in Parkinson’s disease. The purpose of the research was to evaluate the safety and efficacy of MRgFUS to improve limb tremor in the treatment of Parkinson’s disease. Data obtained from two small randomized clinical trials found the MRgFUS group showed significant improvement in limb tremor for the treatment group, and a greater ability to perform daily activities compared to the sham group. Authors concluded the studies demonstrated the beneficial effects of MRgFUS in Parkinson’s disease patients with no serious side effects or adverse events.

3. U.S. Food & Drug Administration Information
4. VA generally only approves use of medical devices that have received at least Food & Drug Administration (FDA) clearance for 510(k) Premarket Notification. The following device has received Premarket Approval from the FDA and is indicated for idiopathic essential tremor patients with medication-refractory tremor and medication-refractory tremor in tremor-dominant Parkinson’s disease.

To search for devices that have received FDA 510(k) clearance or Premarket Approval (PMA), please visit the FDA Devices database.

4. Medicare Coverage Determinations
   Available Medicare national and local coverage determinations are listed below as a resource. VA and Medicare are governed by separate laws and regulations; thus, VA coverage determinations may be different.

5. NCD Number	Name	Effective Date
   None	N/A	N/A

   LCD Number	Contractor	Original/Revision Effective Date
   L33790	CGS Administrators, LLC	01/01/2020
   L37421	National Government Services, Inc.	03/01/2026
   L37729	Noridian Healthcare Solutions, LLC	09/11/2025
   L37761	Palmetto GBA	06/02/2024
   L38495	Novitas Solutions, Inc.	07/12/2020
   L38506	First Coast Service Options, Inc.	07/12/2020

   • NCD: National Coverage Determination
   • LCD: Local Coverage Determination

5. TRICARE Policy Manual
6. Available TRICARE coverage determinations are listed below as a resource. VA and TRICARE are governed by separate laws and regulations; thus, VA coverage determinations may be different.

TRICARE Policy Manual 6010.60-M, Chapter 04, Section 20.1

• 2.14 Unilateral thalamotomy using Magnetic Resonance Image Guided Focused Ultrasound Surgery (MRgFUS) for the treatment of medication-refractory essential tremor may be covered when provided with FDA-approved devices and in accordance with the American Society for Stereotactic and Functional Neurosurgery coverage criteria.

6. Health Care Procedural Coding Information
7. The following CPT^®/HCPCS codes listed in this section are provided for informational purposes only. Inclusion or exclusion of a code does not constitute or imply VA coverage or provider reimbursement. The list of codes may not be all-inclusive since the American Medical Association (AMA) and Centers for Medicare & Medicaid Services (CMS) code updates may occur more frequently than CDI updates. Please refer to section II.a. in this document to review indications and clinical criteria for medical necessity.

   The following CPT codes may be considered medically necessary/covered if the indications and clinical criteria outlined in section II.a. are met. Additional codes may also apply.

   CPT Code	Description
   61715	Magnetic resonance image guided high intensity focused ultrasound (MRgFUS), stereotactic ablation of target, intracranial, including stereotactic navigation and frame placement, when performed

   CPT copyright 2026 American Medical Association. All rights reserved.

IV. Definitions

Term	Definition
Ablate/Ablation	A procedure where a type of energy is used to remove or destroy targeted tissue in the body
Anticonvulsants	A type of drug that can be used to prevent or treat seizures or convulsions by controlling abnormal electrical activity in the brain used to treat epilepsy and other seizure disorders. These medications have proven beneficial in a variety of other disorders, including essential tremor
Benign	A non-cancerous tumor, not harmful in effect
Beta blockers	A class of medications used to help reduce blood pressure; act to block adrenergic receptors responsible for increased cardiac action. Beta blockers, most commonly propranolol, are first line medications for the treatment of essential tremor
Bradykinesia	Impairment of voluntary motor control and slow movements or freezing
Clinical rating scale for tremor	A tool used to rate the severity of the tremor
Comorbidity	Having two or more diseases at the same time
Contralateral	Occurring on or acting in conjunction with a part on the opposite side of the body
Deep brain stimulation	A surgical procedure that implants electrodes in certain areas of the brain to control abnormal brain activity
Dopaminergic agents	Medications aimed to replace dopamine or prevent the degradation of dopamine
Dyskinesia	Uncontrolled, involuntary muscle movements ranging from shakes, tics and tremors to full-body movements
Essential Tremor	A neurological disorder that causes your hands, head, trunk, voice, or legs to shake rhythmically
Gait disturbance	Disruption of the ability to walk
Heterogeneous	Consisting of or composed of dissimilar elements or ingredients; not having a uniform quality throughout
Kinetic	Occurs with voluntary movement
Levodopa-induced dyskinesia	Involuntary, purposeless, predominantly choreiform movements due to long-standing chronic levodopa therapy
Medication refractory	Not responding to or not able to be treated with medication, after consideration of or trial of at least 2 agents at adequate doses
Neurodegenerative	A type of disease in which cells of the central nervous system stop working or die; usually getting worse over time and having no cure
Paresthesia	Abnormal sensation, tingling or pricking felt in the hands, arms, or legs
Parkinsonism	General term that refers to a group of neurological disorders that cause movement problems similar to those seen in Parkinson’s disease such as tremors, slow movement and stiffness
Phenotype	The observable characteristics or traits of a disease
Re-emergent postural form	Occurs when holding a body part motionless against the force of gravity and the tremor commences after a variable latency of one to several seconds
Refractory	Resistant to treatment or cure
Sham procedure	Placebo surgery or treatment – intervention that omits the step thought to be therapeutically necessary
Skull density ratio	The ratio of cortical to cancellous bone, which is used to estimate the density of the skull
Stereotactic	Involving a technique that targets a specific area with the assistance of image guidance
Superimposed	Combines the volume render features with a side by side visual of two chosen images
Thalamotomy	A surgical procedure in which a lesion is made in the thalamus to improve the overall brain function in patients
Thalamus	A paired gray matter structure of the diencephalon near the brain’s center that is responsible for several functions including the relay of different sensory signals to other parts of the brain
Thermographic	A procedure that uses a heat-sensing infrared camera to record the surface heat produced by different parts of the body
Ventralis intermedius nucleus	A part of the thalamus, the Vim is centrally placed in the dentato-thalamo-cortical pathway and is a key surgical target in the treatment of severe medically refractory tremor

V. References

Abusrair, A. H., Elsekaily, W., & Bohlega, S. (2022). Tremor in Parkinson’s Disease: From Pathophysiology to Advanced Therapies. Tremor and other hyperkinetic movements (New York, N.Y.), 12, 29.

Andreasi, N. G., Cilia, R., Romito, L. M., Bonvegna, S., Straccia, G., Elia, A. E., Novelli, A., Messina, G., Tringali, G., Vincenzo  Levi, Devigili, G., Rinaldo, S., Gasparini, V., Grisoli, M., Stanziano, M., Ghielmetti , F., Prioni, S., Bocchi, E., Amami , P., Eleopra, R. (2022). Magnetic Resonance–Guided Focused Ultrasound Thalamotomy May Spare Dopaminergic Therapy in Early-Stage Tremor-Dominant Parkinson’s Disease: A Pilot Study. International Parkinson and Movement Disorder Society. 

Bond, A. E., Shah, B. B., Huss, D. S., Dallapiazza, R. F., Warren, A., Harrison, M. B., Sperling, S. A., Wang, X. Q., Gwinn, R., Witt, J., Ro, S., & Elias, W. J. (2017). Safety and Efficacy of Focused Ultrasound Thalamotomy for Patients With Medication-Refractory, Tremor-Dominant Parkinson Disease: A Randomized Clinical Trial. JAMA neurology, 74(12), 1412–1418. 

Centers for Medicare and Medicaid Services (CMS), Magnetic-Resonance-Guided Focused Ultrasound Surgery (MRgFUS) for Essential Tremor. LCD L38495.

Chang, J. W., Park, C. K., Lipsman, N., Schwartz, M. L., Ghanouni, P., Henderson, J. M., Gwinn, R., Witt, J., Tierney, T. S., Cosgrove, G. R., Shah, B. B., Abe, K., Taira, T., Lozano, A. M., Eisenberg, H. M., Fishman, P. S., & Elias, W. J. (2018). A prospective trial of magnetic resonance-guided focused ultrasound thalamotomy for essential tremor: Results at the 2-year follow-up. Annals of neurology, 83(1), 107–114.

Chua, M. M. J., Blitz, S. E., Ng, P. R., Segar, D. J., McDannold, N. J., White, P. J., Christie, S., Hayes, M. T., Rolston, J. D., & Cosgrove, G. R. (2023). Focused Ultrasound Thalamotomy for Tremor in Parkinson’s Disease: Outcomes in a Large, Prospective Cohort. Movement disorders: official journal of the Movement Disorder Society, 38(10), 1962–1967.

Cosgrove, G. R., Lipsman, N., Lozano, A. M., Chang, J. W., Halpern, C., Ghanouni, P., Eisenberg, H., Fishman, P., Taira, T., Schwartz, M. L., McDannold, N., Hayes, M., Ro, S., Shah, B., Gwinn, R., Santini, V. E., Hynynen, K., & Elias, W. J. (2022). Magnetic resonance imaging-guided focused ultrasound thalamotomy for essential tremor: 5-year follow-up results. Journal of neurosurgery, 138(4), 1028–1033.

Department of Health & Human Services. (2001). Essential tremor. Better Health Channel.

Essential Tremor. (2023). Mayo Clinic. Retrieved May 13, 2023.

Ge, Y., Wang, Z., Gu, F., Yang, X., Chen, Z., Dong, W., & Wang, Z. (2021). Clinical application of magnetic resonance-guided focused ultrasound in Parkinson’s disease: a meta-analysis of randomized clinical trials. Neurological sciences: official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology, 42(9), 3595–3604.

Health Quality Ontario (2018). Magnetic Resonance-Guided Focused Ultrasound Neurosurgery for Essential Tremor: A Health Technology Assessment. Ontario health technology assessment series, 18(4), 1–141

Kaplitt, M. G., Krishna, V., Eisenberg, H. M., Elias, W. J., Ghanouni, P., Baltuch, G. H., Rezai, A., Halpern, C. H., Dalm, B., Fishman, P. S., Buch, V. P., Moosa, S., Sarva, H., & Murray, A. M. (2024). Safety and Efficacy of Staged, Bilateral Focused Ultrasound Thalamotomy in Essential Tremor: An Open-Label Clinical Trial. JAMA neurology, 81(9), 939–946.

Lak, A. M., Segar, D. J., McDannold, N., White, P. J., & Cosgrove, G. R. (2022). Magnetic resonance image guided focused ultrasound thalamotomy. A single center experience with 160 procedures. Frontiers.

Meng, Y., Huang, Y., Solomon, B., Hynynen, K., Scantlebury, N., Schwartz, M. L., & Lipsman, N. (2017). MRI-guided Focused Ultrasound Thalamotomy for Patients with Medically-refractory Essential Tremor. Journal of visualized experiments : JoVE, (130), 56365. 

Pouratian, N., Baltuch, G., Elias, W. J., & Gross, R. (2020). American Society for Stereotactic and Functional Neurosurgery Position Statement on Magnetic Resonance-Guided Focused Ultrasound for the Management of Essential Tremor. Neurosurgery, 87(2), E126–E129. 

Torrico TJ, Munakomi S. (2022). Neuroanatomy, Thalamus. Treasure Island (FL). StatPearls. Retrieved on June 15, 2023.

U.S. Food & Drug Administration Premarket Approval (PMA) Database. (n.d.). Retrieved May 13, 2023.

VI. CDI History/Revision Information

Date	Summary of Updates
08/01/2026	Updated Benign in “Definitions” section    Updated “Limitations/Exclusions” section with the following limitation: History of contralateral thalamotomy less than nine months from the initial treatment   Added evidence summary from Kaplitt et al. (2024) to “Research, Clinical Trials, and Evidence Summaries”   Added section “TRICARE Policy Manual”
08/29/2024	New CDI created describing medically necessary and not medically necessary indications

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