Aetna Thalamotomy Coverage Prior Auth

Coverage Criteria for Thalamotomy Procedures

inv-01: Unilateral thalamotomy — movement disorders

Covered when ALL of the following are met

Primary selection criteria: 1) Member has a history of positive response to drug therapy (initial positive response to medication with subsequent refractoriness); 2) Member has been screened by a neurologist with expertise in movement disorders to ensure all appropriate non-surgical therapies have been tried; 3) Member has severe and incapacitating tremors and medical therapy has failed as indicated by worsening of symptoms and/or disabling medication side effects.

Applies to unilateral thalamotomy for movement disorders including dystonia, Parkinson's disease, spasmodic torticollis, and tremor.

inv-02: Focused ultrasound thalamotomy — essential tremor

Covered when ALL of the following are met

Focused ultrasound for ET: 1) Severe essential tremor (ET) inadequately responsive to medical therapy; 2) Patient selection and pre-procedure assessment consistent with device/procedure requirements (including MRI eligibility and skull characteristics suitable for transcranial sonication); 3) Treatment planned as unilateral MRgFUS targeting the ventral intermediate nucleus (VIM) as per available controlled trials and device indications.

MRgFUS is considered medically necessary for severe ET not responsive to medical therapy; long-term durability and patient selection considerations are noted in evidence.

inv-03: Gamma knife thalamotomy — indications

Covered when ANY of the following indications are met and selection criteria for thalamotomy are satisfied

Gamma knife indications: 1) Severe essential tremor inadequately responsive to medical therapy; OR 2) Refractory disabling tremor and rigidity from Parkinson's disease in persons who meet the unilateral thalamotomy medical necessity criteria; OR 3) Last-resort treatment for malignant (intractable) pain when ALL of the following apply: advanced oncologic disease with limited life expectancy; options for radiotherapy have been exhausted; best medical treatment has failed or produced intolerable side effects; pain has failed targeted interventions (e.g., nerve blocks); and there are no technical limitations or medical contraindications to thalamotomy.

Gamma knife (stereotactic radiosurgery) may be considered medically necessary for these indications when thalamotomy selection criteria are met.

inv-04: Coverage with conditions (trial-derived)

Coverage consideration when ALL of the following trial-based conditions are met

Trial-derived coverage conditions: 1) Patient has clinically significant tremor (e.g., essential tremor or tremor-dominant Parkinson disease) causing functional impairment; 2) Tremor is medication-refractory (failed ≥2 adequate trials of medical therapy for ET as enrolled in randomized trials); 3) Procedure planned is unilateral MRgFUS targeting the VIM as used in pivotal trials; 4) Pre-procedure evaluation documents skull density/geometry permitting adequate thermal rise for safe and effective sonication; 5) Baseline and planned follow-up outcome assessments (e.g., CRST, UPDRS, and validated QOL instruments) are documented consistent with trial timepoints (1, 3, 6, 12 months and longer as applicable).see node text

These conditions are derived from inclusion criteria and feasibility/efficacy trial protocols and should be documented during authorization and care planning.

inv-05: Candidate selection / appropriateness

Coverage may be considered for MRgFUS thalamotomy when ALL of the following apply (per evidence and expert consensus):

Candidate selection / appropriateness: 1) Confirmed diagnosis of essential tremor (or other medication-resistant tremor syndrome) with disabling appendicular tremor; 2) Failure of first-line medical therapies as judged by a movement-disorders neurologist; 3) Unilateral treatment planned (or staged bilateral approach documented with rationale and timing); 4) Patient is eligible for MRI and has skull characteristics permitting transcranial focused ultrasound (suitability documented by skull density/volume assessment); 5) Informed consent documents discussion of limited long-term data, potential persistent adverse events, and alternatives (e.g., DBS, RF thalamotomy, SRS).

Based on ASSFN consensus and multiple clinical studies; unilateral approach preferred and bilateral procedures remain investigational except in staged, carefully selected cases.

inv-06: Efficacy and durability

Expected outcomes and limitations:

Efficacy and durability summary: 1) Short- to mid-term outcomes demonstrate significant improvement in tremor severity and quality of life (pooled CRST total improvement approximately 62%); 2) Benefits are often durable to 1–4 years in published cohorts though some metrics may show mild degradation over time and longer-term durability remains incompletely characterized; 3) Trial and cohort follow-up show participant attrition at multi-year timepoints, which may influence observed long-term effect estimates; 4) Comparative effectiveness versus alternatives (e.g., DBS) varies by indication and laterality and should be considered when selecting intervention.

Derived from meta-analyses and multi-year follow-up studies; data limitations include heterogeneity and limited long-term randomized evidence.

inv-07: Safety profile

Safety considerations — common and persistent adverse events:

Safety profile: Transient in-procedure events: headache, vertigo/dizziness, nausea; Early post-procedure events: burning scalp sensation, lip or oral paresthesia, transient speech or motor abnormalities; Persistent adverse events reported in trials and meta-analyses include gait disturbance (reported in up to ~36% acutely with persistence in ~9% at 12 months in a large trial) and sensory disturbances/paresthesia (reported in ~38% acutely with persistent paresthesia ~14–15% at 12 months); overall pooled persisting paresthesia ~15.3% at 12 months in meta-analysis.

Persistent AEs may be more common with MRgFUS than some alternatives; patient selection and counseling regarding risk of lasting sensory or gait problems is essential.

inv-08: Indications and evidence summaries

Clinical indications and evidence summary described in this section:

MRgFUS for Essential Tremor (ET): ASSFN consensus and randomized trial evidence support unilateral MRgFUS VIM thalamotomy for medically refractory essential tremor in carefully selected patients, with documented improvement in tremor scores and quality-of-life measures in randomized and open-label studies.unilateral

References include randomized sham-controlled and multi-year follow-up studies (Elias et al.; Chang et al.; Halpern et al.; Pouratian et al.).

Bilateral-staged MRgFUS for ET: Small case-series (n=9) report feasibility and potential effectiveness for staged bilateral MRgFUS with improvements in CRST scores and mostly transient AEs, but controlled trials are lacking and routine bilateral application remains investigational.staged bilateral with documented interval (e.g., ≥5 months in series)

Martinez-Fernandez et al. 2021

MRgFUS Thalamotomy for Parkinson Disease Tremor:

The policy identifies that bilateral thalamotomy is considered experimental/investigational and not recommended. Specific listed indications for which thalamotomy is considered investigational include treatment of fragile X‑associated tremor/ataxia syndrome, multiple sclerosis–associated tremor, non‑essential tremor syndromes (e.g., dystonic tremor, dystonia gene–associated tremor, Parkinson’s disease in some contexts), obsessive‑compulsive disorder, and non‑malignant pain as well as ventro‑oral thalamotomy for focal hand dystonia.

The document warns that MRgFUS thalamotomy produces a nonreversible brain lesion and therefore bilateral MRgFUS is discouraged because of the risk of persistent adverse effects, including potential speech and swallowing impairment. The non‑adjustable, permanent nature of the lesion contrasts with implantable approaches (e.g., DBS) where stimulation settings can be modified post‑operatively.

Eligibility for MRgFUS may be limited by anatomic and clinical factors. Pre‑procedure assessment of skull density/geometry is required because low or unfavorable skull characteristics can prevent achieving adequate thermal rise. The procedure is not suitable for patients with MRI contraindications (for example, implanted pacemakers), for some patients with high skull thickness or density, and for those with prior intracranial surgery because these conditions can impede safe or effective sonication. Additionally, MRgFUS requires patient immobility during sonication and adequate intra‑procedure monitoring, which may preclude some patients from candidacy.

An external evidence source (UpToDate; Comella, 2019) referenced in the document does not list ventro‑oral thalamotomy among therapeutic options for focal dystonia, indicating limited guideline support for this approach in focal hand dystonia.

The Clinical Policy Bulletin is intended to assist in administering plan benefits but does not constitute a contract or an offer of coverage. It is a general description of plan or program benefits, may be updated, and does not guarantee results or outcomes.

Consistent with the exclusions and not‑medically‑necessary statements in the policy, thalamotomy is considered investigational/experimental for bilateral procedures and for the listed indications such as fragile X‑associated tremor/ataxia, MS‑associated tremor, various non‑ET tremor syndromes, obsessive‑compulsive disorder, non‑malignant pain, and ventro‑oral thalamotomy for focal hand dystonia.

The policy and cited literature outline limitations of MRgFUS including limited long‑term data and variable durability of benefit (with reports of loss of effect over months to years), variable efficacy across patients, a relatively high rate of some persistent neurologic adverse events (for example, persistent paresthesia and gait disturbance reported in trials), and technical constraints related to skull characteristics and imaging/targeting that can limit treatment applicability and outcomes.

Although the extract does not present explicit not‑medically‑necessary (NMN) rules beyond the stated exclusions, comparative evidence cited in the document indicates that deep brain stimulation (DBS), particularly bilateral DBS, may provide superior tremor reduction in some patients, and that MRgFUS is associated with different and in some cases higher rates of persistent neurologic adverse events compared with DBS—information that may influence determinations about optimal therapy selection.

The policy concludes that there is insufficient high‑quality evidence to support routine bilateral MRgFUS ablation or broad expansion of MRgFUS to additional targets (e.g., sub‑thalamotomy, pallidotomy) or to routine stereotactic radiosurgery medial thalamotomy outside of select or palliative contexts. Small case series of staged bilateral MRgFUS show feasibility but controlled trials are needed before routine adoption.

Coding and Billing

Covered CPT Codes (radiofrequency stereotactic thalamotomy)CPTCovered

61720

Creation of lesion by stereotactic method, including burr hole(s) and localizing and recording techniques, single or multiple stages; globus pallidus or thalamus.

Covered CPT Codes (gamma knife thalamotomy)CPTCovered

61796	Stereotactic radiosurgery (particle beam, gamma ray or linear accelerator), 1 simple cranial lesion.
61797	each additional cranial lesion, simple (List separately in addition to code for primary procedure).
61798	1 complex cranial lesion.
61799	each additional cranial lesion, complex (List separately in addition to code for primary procedure).

Covered CPT Codes (focused ultrasound thalamotomy)CPTCovered

0398T

Magnetic resonance image guided high intensity focused ultrasound (MRgFUS), stereotactic ablation lesion, intracranial for movement disorder including stereotactic navigation and frame placement when performed.

HCPCS codes not covered if selection criteria are metHCPCSNot Covered

C9734

Focused ultrasound ablation/therapeutic intervention, other than uterine leiomyomata, with magnetic resonance (MR) guidance.

ICD-10 Codes covered if selection criteria are metICD-10Covered

G20	Parkinson's disease.
G21.0-G21.9	Secondary Parkinsonism.
G24.01-G24.9	Dystonia.
G24.3	Spasmodic torticollis.
G25.0-G25.9	Other extrapyramidal and movement disorders.
G89.3	Neoplasm related pain (acute) (chronic).
G25.0	Essential tremor.

ICD-10 Codes not covered / experimental indicationsICD-10Not Covered

F42.2-F42.9	Obsessive-compulsive disorder.
G89.0-G89.29	Pain, not elsewhere classified.
G89.4	Chronic pain syndrome.
R52	Pain, unspecified.
G25.1	Drug-induced tremor [multiple sclerosis-associated tremor].
G25.2	Other specified forms of tremor [multiple sclerosis-associated tremor].
Q99.2	Fragile X syndrome.
G24.8	Other dystonia [focal hand dystonia].

Procedure and modality groups discussed (no explicit codes in excerpt)mixed

No codes listed

Provider Actions, Prior Authorization, and Documentation

Denial Risk

Denial risk for unmet selection criteria

Procedures may be denied if documentation does not demonstrate that the member meets the policy selection criteria. Denial risk is increased when there is no history of an initial positive response to medication followed by refractoriness, lack of neurologist screening confirming all appropriate non‑surgical therapies were tried, absence of severe incapacitating tremor or failure of medical therapy, or when planned treatment is bilateral without justification. Also document absence of contraindications and technical feasibility for the planned modality.

Denial risk if selection criteria not met (e.g., no prior positive medication response)
Denial risk for bilateral procedures not supported by policy guidance

Prior Authorization

Skull characteristics affecting eligibility

Some MRgFUS failures have been associated with skull characteristics that prevent adequate thermal rise (for example, low skull density or unfavorable cortical-to-bone marrow thickness ratio). Evaluate skull density/volume and other skull characteristics prior to MRgFUS; document imaging assessment and any determinations of suitability.

Background and Rationale

Thalamotomy is a stereotactic surgical lesioning procedure that targets the thalamus to reduce tremor and rigidity in movement disorders. It is typically performed using stereotactic methods under local anesthesia, with the ventral intermediate nucleus (VIM) commonly targeted for tremor control. The procedure can improve tremor but generally has little effect on akinesia or bradykinesia; outcomes are influenced by precise targeting, imaging guidance, and patient selection.

Definitions and Key Terms

Target nucleus for tremor lesions

Target nucleusVIM (ventralis intermedius nucleus)

Location detailsPart of the ventralis lateralis nucleus, typically targeted ~4 mm posterior to AC-PC midpoint, ~13 mm lateral, and ~1 mm above AC-PC line as described in stereotactic targeting.

Clinical rolePreferred lesion location for treating various tremors (essential tremor and Parkinsonian tremor).

Magnetic resonance-guided focused ultrasound ablative procedure for thalamotomy

Procedure nameMagnetic resonance-guided focused ultrasound ablative procedure for thalamotomy (MRgFUS / focused ultrasound thalamotomy)

Indication noteAetna considers focused ultrasound thalamotomy medically necessary for severe essential tremor inadequately responsive to medical therapy.

Policy Revision History

1997-03-31effective

Policy effective date established.

2023-04-06last_reviewLatest

Policy last reviewed.

2024-02-08next_review

Next scheduled policy review date.