I66 ICD-10-CM Code: Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
A clear reference for the official code description, hierarchy, and related coding information from the FY 2027 U.S. release.
Official description
I66Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
ICD-10-CM diagnosis code · United States clinical modification
Where I66 sits
- 1
Chapter 9
Diseases of the circulatory system (I00-I99)
- 2
Section
Cerebrovascular diseases (I60-I69)
- 3
Category I66
Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
- 4
Code I66
Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
Codes under I66
I66 is a non-billable category. Choose the child code that best matches the documented diagnosis.
I66.0Occlusion and stenosis of middle cerebral arteryI66.1Occlusion and stenosis of anterior cerebral arteryI66.2Occlusion and stenosis of posterior cerebral arteryI66.3Occlusion and stenosis of cerebellar arteriesI66.8Occlusion and stenosis of other cerebral arteriesI66.9Occlusion and stenosis of unspecified cerebral arteryNotes for this code
Inclusion terms
No inclusion terms are listed for I66.
Code first
No “code first” instruction is listed for I66.
Use additional code
No “use additional code” instruction is listed for I66.
Excludes1
Conditions that should not be reported together with this code.
- Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5)
Excludes2
Conditions not included here that may be reported separately when present.
No Excludes2 note is listed for I66.
Source and release
- Data release
- U.S. ICD-10-CM · FY 2027
- Effective date
- Oct 1, 2026
- Publisher
- Vero Scribe Inc.
This reference is generated from Vero’s ICD-10-CM description, hierarchy, and code-note dataset. The visible content and structured data share that source.
Frequently asked questions
What does ICD-10-CM code I66 mean?
I66 is the FY 2027 U.S. ICD-10-CM code for “Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction.”
Is I66 a billable or specific ICD-10-CM code?
No. I66 has more specific child codes in the FY 2027 reference data. Select the code that matches the documentation and confirm the active code set and payer requirements.
Where is I66 located in ICD-10-CM?
I66 is listed in Chapter 9, Diseases of the circulatory system (I00-I99), within Cerebrovascular diseases (I60-I69) (I60–I69), under category I66, Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction.
What coding notes are listed for I66?
No inclusion terms are listed for I66 in this reference record. No code-first instruction is listed. Excludes1 notes: Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5). No Excludes2 note is listed.