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ICD-10 Code I66.0: Occlusion and stenosis of middle cerebral artery

I66.0 is an ICD-10 diagnosis entry used to group records related to Occlusion and stenosis of middle cerebral artery. You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen. ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Diseases of the circulatory system (I00-I99).

What is this code?

ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Diseases of the circulatory system (I00-I99).

When is it used?

  • May be used when a clinician documents occlusion and stenosis of middle cerebral artery in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code may act more like a grouping or parent code, so a more specific child code may be used in final documentation when available.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
  • This entry may represent a broader category rather than the most specific billable code.

Code hierarchy

chapter
9Diseases of the circulatory system (I00-I99)
block
I60-I69Cerebrovascular diseases
category
I66Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
currentI66

Where you may see this code

You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen.

Related specialists

CardiologistGeneral Physician

Coding guidelines

Compatibility

Legacy code aligns to an official FY 2026 category. Frontend should resolve to the official category page and surface the billable child codes.
Legacy codes
I66.0
Replacement codes
I66.01 — Occlusion and stenosis of right middle cerebral arteryI66.02 — Occlusion and stenosis of left middle cerebral arteryI66.03 — Occlusion and stenosis of bilateral middle cerebral arteriesI66.09 — Occlusion and stenosis of unspecified middle cerebral artery

Common synonyms

Occlusion and stenosis of middle cerebral artery

Frequently asked questions

Code details

CodeI66.0
SystemICD10
Display nameOcclusion and stenosis of middle cerebral artery
ChapterDiseases of the circulatory system (I00-I99)
BlockCerebrovascular diseases

Flags

BillableNo
Valid clinical useNo

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.