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I66.09

I66.09: Occlusion and stenosis of unspecified middle cerebral artery

Billable / specific codeICD-10-CM

I66.09 is a billable, specific ICD-10-CM code for occlusion and stenosis of unspecified middle cerebral artery. It is valid for submission on a claim.

Check I66.09 with the rest of the claim: free scrubber

Excludes1 inherited from the categories above I66.09

A category’s note binds every code beneath it.

Written on I66: Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction

  • Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5)

Risk adjustment

No CMS-HCC V28 category: this code does not change a RAF score.

Medicare coverage

I66.09 is named in 9 Medicare coverage policies: 9 listing it as supporting medical necessity. Which one applies depends on your Medicare contractor.

  • A52868Billing and Coding: Transesophageal Echocardiography (TEE)
  • A56722Billing and Coding: Intraoperative Neurophysiological Testing
  • A56781Billing and Coding: Transthoracic Echocardiography (TTE)
  • A57174Billing and Coding: MolDX: Pharmacogenomics Testing

Code history

Unchanged in every release from FY2024 to FY2027.

Other codes under I66.0

ICD-10-CMFY2027· effective October 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release: see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.