ICD-10 · PDGM grouping
I66 Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
All 15 codes in the I66 family, with the PDGM clinical group, comorbidity subgroup and primary-position rule CMS assigns, read from the CMS grouper crosswalk v07.2.26 and the CDC FY2027 code file.
Codes in family
15
Can lead a claim
15
Cannot lead a claim
0
What CMS assigns to I66
All 15 codes group to Neuro Rehabilitation. 11 of the 15 count toward the Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction comorbidity subgroup; 4 are assigned none. Every code can lead a claim.
- Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction
Every code in I66
Descriptions are CDC’s FY2027 wording; where CMS’s grouper abbreviates one, its form is shown beneath.
| Code | Description | Primary position | Clinical group | Comorbidity subgroup |
|---|---|---|---|---|
| I66.0 Occlusion and stenosis of middle cerebral artery | ||||
| I66.01 | Occlusion and stenosis of right middle cerebral artery | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.02 | Occlusion and stenosis of left middle cerebral artery | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.03 | Occlusion and stenosis of bilateral middle cerebral arteries | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.09 | Occlusion and stenosis of unspecified middle cerebral artery | Can lead a claim | B | None |
| I66.1 Occlusion and stenosis of anterior cerebral artery | ||||
| I66.11 | Occlusion and stenosis of right anterior cerebral artery | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.12 | Occlusion and stenosis of left anterior cerebral artery | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.13 | Occlusion and stenosis of bilateral anterior cerebral arteriesCMS: Occlusion and stenosis of bi anterior cerebral arteries | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.19 | Occlusion and stenosis of unspecified anterior cerebral arteryCMS: Occlusion and stenosis of unsp anterior cerebral artery | Can lead a claim | B | None |
| I66.2 Occlusion and stenosis of posterior cerebral artery | ||||
| I66.21 | Occlusion and stenosis of right posterior cerebral artery | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.22 | Occlusion and stenosis of left posterior cerebral artery | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.23 | Occlusion and stenosis of bilateral posterior cerebral arteriesCMS: Occlusion and stenosis of bi posterior cerebral arteries | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.29 | Occlusion and stenosis of unspecified posterior cerebral arteryCMS: Occlusion and stenosis of unsp posterior cerebral artery | Can lead a claim | B | None |
| I66.3 | Occlusion and stenosis of cerebellar arteries | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.8 | Occlusion and stenosis of other cerebral arteries | Can lead a claim | B | Occlusion/Stenosis of Pre-cerebral/Cerebral Arteries w/o Cerebral Infarction |
| I66.9 | Occlusion and stenosis of unspecified cerebral artery | Can lead a claim | B | None |
Sources: CMS HH PPS Grouper Software v07.2.26, effective 2026-10-01, for the clinical group, comorbidity subgroup, code-first conventions and primary-position flags; CDC NCHS ICD-10-CM FY2027 code descriptions for the family title and code wording. This is the crosswalk Medicare runs a claim through. Grouping also depends on admission source, timing, the OASIS functional items and the rest of the diagnosis list.
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