CMS NCD 319: Blood Brain Barrier Osmotic Disruption — What Billing Teams Need to Know in 2026

CMS has issued a modified update to National Coverage Determination (NCD) 319, governing the use of osmotic blood brain barrier disruption (BBBD) as a treatment approach for brain tumors. This policy, administered by the Centers for Medicare & Medicaid Services, maintains a non-coverage determination for osmotic BBBD when used as part of a brain tumor treatment regimen — a position CMS has held since March 2007. If your facility or practice bills for neuro-oncology services, understanding the full scope of this NCD is critical to avoiding claim denials and ensuring compliant documentation.

What Is Blood Brain Barrier Disruption — and Why Does CMS Cover It?

The blood brain barrier (BBB) is a tightly regulated structure formed by endothelial cells lining the brain's capillaries. These cells form what are called tight junctions — essentially a filtration system that prevents most substances, including many chemotherapy agents, from entering brain tissue. This biological gatekeeping mechanism is protective under normal circumstances, but it presents a significant clinical challenge in the treatment of malignant primary or metastatic brain tumors.

Blood brain barrier disruption (BBBD) refers to techniques designed to temporarily break down those tight junctions, theoretically increasing the concentration of anti-cancer drugs delivered to a tumor and extending how long those drugs remain in contact with tumor cells. Three primary approaches exist: osmotic disruption (the most widely used), bradykinin-mediated disruption, and irradiation-based disruption.

Osmotic BBBD typically involves the intra-arterial infusion of a hyperosmotic agent — such as mannitol — to transiently open the BBB, followed by administration of chemotherapeutic agents. The procedure requires hospitalization, intensive monitoring, and repeated imaging. Because of this complexity, it falls under two Medicare benefit categories: inpatient hospital services and services incident to a physician's professional service.

CMS NCD 319 Coverage Determination: What Is and Isn't Covered

Here is where billing teams need to pay close attention. NCD 319 draws a clear line.

Non-covered: Effective for services performed on or after March 20, 2007, the Centers for Medicare & Medicaid Services has determined that osmotic BBBD is not reasonable and necessary when used as part of a treatment regimen for brain tumors. This is an explicit national non-coverage determination — meaning no local coverage determination (LCD) can override it, and no amount of medical necessity documentation will make a Medicare claim for osmotic BBBD payable.

Covered (unchanged): NCD 319 explicitly states that it does not alter coverage for anti-cancer chemotherapy itself. If a patient receives standard chemotherapy for a brain tumor — even in conjunction with, or following, a BBBD procedure — the chemotherapy component remains covered under existing Medicare policy. The non-coverage applies specifically to the osmotic BBBD procedure, not to the broader cancer treatment regimen.

This distinction matters for facilities that may be billing a bundled claim inclusive of chemotherapy administration and the BBBD procedure. Separating those services correctly in your claim is essential to ensure the chemotherapy component is not inadvertently denied alongside the non-covered BBBD service.

Why CMS Continues to Classify Osmotic BBBD as Not Reasonable and Necessary

CMS's position, last formally reviewed in March 2007, is based on the determination that osmotic BBBD lacks sufficient evidence to meet the "reasonable and necessary" standard under Section 1862(a)(1)(A) of the Social Security Act. That standard requires that a service be safe, effective, and appropriate for the diagnosed condition — and that it not be experimental or investigational in nature for the covered indication.

The theoretical premise of BBBD is scientifically sound: improving drug delivery to brain tumors is a legitimate clinical goal. But the evidence base for osmotic disruption specifically has not risen to the level required for a nationally covered indication. CMS has made no covered indications designation under Section B of NCD 319 — that section reads "N/A." This is significant. It means there is no subset of patients, no specific tumor type, and no clinical scenario under which Medicare will reimburse osmotic BBBD as part of brain tumor treatment.

For neuro-oncology practices exploring BBBD as part of a clinical trial, separate coverage rules under Medicare's Coverage with Evidence Development (CED) framework may apply — but that determination would require its own NCD or CED designation, which does not currently exist for this service.

Affected Codes

The policy does not list specific CPT or HCPCS codes. NCD 319 applies broadly to osmotic blood brain barrier disruption services regardless of the specific procedure code used to bill them. Billing teams should work with their coding teams to identify any internal charge codes or CPT codes used for BBBD-related procedures and confirm those claims are not being submitted to Medicare payers.

Covered Codes

No codes are designated as covered under NCD 319. The policy contains no nationally covered indications.

Non-Covered Services

Related ICD-10 Diagnosis Codes

No specific ICD-10-CM codes are listed in the policy document. Diagnoses associated with malignant primary or metastatic brain tumors (such as codes in the C71.x range for malignant neoplasms of the brain) would be the relevant diagnosis codes in the context of this NCD — but the non-coverage determination applies regardless of diagnosis code submitted.

What Your Billing Team Should Do