Chiari Malformation Decompression Surgery — CPB 0931 | AETNA Coverage Update

Aetna modified CPB 0931 for Chiari malformation decompression surgery, effective January 5, 2026. Here's what billing teams need to know.

Aetna, a CVS Health company updated its coverage policy for Chiari malformation decompression surgery under CPB 0931 Aetna's clinical policy bulletin system. The change refines medical necessity criteria for Type I malformations and expands the list of procedures considered experimental. If your team bills CPT 61343 for suboccipital craniectomy with cervical laminectomy, this policy directly affects your reimbursement and claim denial risk.

Quick-Reference Table

Aetna Chiari Malformation Decompression Surgery Coverage Criteria and Medical Necessity Requirements 2026

The Aetna Chiari malformation decompression surgery coverage policy divides cases into two tracks. The first track is simple. Types II, III, and IV are medically necessary without additional clinical criteria. If you have the diagnosis codes — Q07.01 for Type II, Q01.0 through Q01.9 for Type III, or Q04.8 for Type IV — and bill CPT 61343, you meet the threshold.

Type I is where this policy gets complicated. Aetna requires radiographic findings of downward cerebellar tonsil displacement of 5 mm or more in adults. In children, the threshold drops to 3 mm. The imaging must also show crowding or compression of neural structures at the foramen magnum. That displacement finding alone doesn't clear the bar — it's necessary but not sufficient.

Beyond the imaging requirement, the member must meet one of two additional conditions. Either they have signs or symptoms related to the Chiari malformation, or they have documented radiographic progression — worsening tonsil displacement or growth of an associated spinal cord syrinx.

The symptom pathway has three sub-requirements, and all three must be documented. First, all other reasonable sources of the symptoms must be ruled out. Second, if the presenting symptoms are isolated headaches or neck pain, a neurologist must direct conservative treatment and document its failure. If no local neurologist or pediatric neurologist is available, a pain specialist is acceptable. Third, if sleep apnea or swallowing difficulty drives the surgical consideration, objective confirmatory testing is required — a sleep study for apnea, a video swallow evaluation for dysphagia.

The real issue here is documentation. Aetna isn't just asking whether the surgery is appropriate. They're asking whether your clinical record proves it step by step. A claim denial on CPT 61343 for a Type I case will almost always trace back to missing documentation on one of these three sub-criteria — not a disagreement about the surgery itself.

Prior authorization is standard for neurosurgical procedures at this complexity level. Confirm your Aetna prior authorization requirements for CPT 61343 before scheduling, particularly for pediatric cases where the 3 mm threshold applies. The medical necessity documentation supporting the prior auth request needs to address each criterion explicitly.

Aetna Chiari Malformation Decompression Surgery Exclusions and Non-Covered Indications

This update adds specificity to what Aetna will not cover. Five procedures or approaches are now explicitly classified as experimental, investigational, or unproven. That classification means no reimbursement, regardless of clinical rationale.

The five exclusions are:

The AI exclusion is new territory. It signals that Aetna is watching how AI-assisted surgical planning and outcome prediction tools are being billed and is drawing a line now, before widespread adoption. If your facility or affiliated surgeons are using AI prediction tools and billing for them, flag this for your compliance officer immediately.

The intradural dissection without dural closure exclusion is clinically significant. Some surgeons prefer this approach to reduce complication risk. Aetna's position is that the evidence doesn't support it. If your neurosurgeons use this technique, they need to know Aetna won't cover it under this coverage policy.

Coverage Indications at a Glance

Aetna Chiari Malformation Decompression Surgery Billing Guidelines and Action Items 2026

These aren't suggestions. The effective date of January 5, 2026 has already passed. Act now.

CPT, HCPCS, and ICD-10 Codes for Chiari Malformation Decompression Surgery Under CPB 0931

Covered CPT Codes (When Selection Criteria Are Met)

Key ICD-10-CM Diagnosis Codes

A note on code pairing: G93.5 is your primary diagnosis code for all Type I claims. The entire symptom and radiographic documentation burden sits on that code. Make sure the clinical record behind it is bulletproof before submitting.