I66: Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
Codes under I66 (Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction). A ✓ marks a billable (fully specified) code; category codes without a ✓ are not billable on their own.
| Code | Description | Billable |
|---|---|---|
| I66.0 | Occlusion and stenosis of middle cerebral artery | — |
| I66.0 | Occlusion and stenosis of middle cerebral artery | — |
| I66.01 | Occlusion and stenosis of right middle cerebral artery | ✓ |
| I66.01 | Occlusion and stenosis of right middle cerebral artery | ✓ |
| I66.1 | Occlusion and stenosis of anterior cerebral artery | — |
| I66.1 | Occlusion and stenosis of anterior cerebral artery | — |
| I66.02 | Occlusion and stenosis of left middle cerebral artery | ✓ |
| I66.02 | Occlusion and stenosis of left middle cerebral artery | ✓ |
| I66.2 | Occlusion and stenosis of posterior cerebral artery | — |
| I66.2 | Occlusion and stenosis of posterior cerebral artery | — |
| I66.03 | Occlusion and stenosis of bilateral middle cerebral arteries | ✓ |
| I66.03 | Occlusion and stenosis of bilateral middle cerebral arteries | ✓ |
| I66.3 | Occlusion and stenosis of cerebellar arteries | ✓ |
| I66.3 | Occlusion and stenosis of cerebellar arteries | ✓ |
| I66.8 | Occlusion and stenosis of other cerebral arteries | ✓ |
| I66.8 | Occlusion and stenosis of other cerebral arteries | ✓ |
| I66.09 | Occlusion and stenosis of unspecified middle cerebral artery | ✓ |
| I66.09 | Occlusion and stenosis of unspecified middle cerebral artery | ✓ |
| I66.9 | Occlusion and stenosis of unspecified cerebral artery | ✓ |
| I66.9 | Occlusion and stenosis of unspecified cerebral artery | ✓ |
| I66.11 | Occlusion and stenosis of right anterior cerebral artery | ✓ |
| I66.11 | Occlusion and stenosis of right anterior cerebral artery | ✓ |
| I66.12 | Occlusion and stenosis of left anterior cerebral artery | ✓ |
| I66.12 | Occlusion and stenosis of left anterior cerebral artery | ✓ |
| I66.13 | Occlusion and stenosis of bilateral anterior cerebral arteries | ✓ |
| I66.13 | Occlusion and stenosis of bilateral anterior cerebral arteries | ✓ |
| I66.19 | Occlusion and stenosis of unspecified anterior cerebral artery | ✓ |
| I66.19 | Occlusion and stenosis of unspecified anterior cerebral artery | ✓ |
| I66.21 | Occlusion and stenosis of right posterior cerebral artery | ✓ |
| I66.21 | Occlusion and stenosis of right posterior cerebral artery | ✓ |
| I66.22 | Occlusion and stenosis of left posterior cerebral artery | ✓ |
| I66.22 | Occlusion and stenosis of left posterior cerebral artery | ✓ |
| I66.23 | Occlusion and stenosis of bilateral posterior cerebral arteries | ✓ |
| I66.23 | Occlusion and stenosis of bilateral posterior cerebral arteries | ✓ |
| I66.29 | Occlusion and stenosis of unspecified posterior cerebral artery | ✓ |
| I66.29 | Occlusion and stenosis of unspecified posterior cerebral artery | ✓ |
Frequently asked questions
What is ICD-10-CM code I66?
I66 is an ICD-10-CM category covering Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction. It contains 36 more specific diagnosis codes, 30 of which are billable.
Is I66 a billable code?
No — I66 is a category header and isn't billable on its own. Code to the highest level of specificity using one of its subcodes (for example I66.0 — Occlusion and stenosis of middle cerebral artery). 30 of the 36 codes under I66 are billable.
What codes fall under I66?
I66 includes I66.0, I66.0, I66.01, I66.01, I66.1, plus 31 more. See the full list with descriptions and billable status above.
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Informational only, not coding or medical advice. Verify against the official ICD-10-CM (FY2026) and your payer's guidelines.
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