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

I66.0 is the ICD-10-CA code for “Occlusion and stenosis of middle cerebral artery” in CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026.

Official description

I66.0

Occlusion and stenosis of middle cerebral artery

Short description: Occlusion stenos middle cerebral artery

ICD-10-CA · Canada · Also written I660

Index terms

Entries in CIHI’s alphabetical index that lead to I66.0. Searching the index by the condition the note names is how coders reach this code.

  • Occlusion, occluded, artery, cerebral, middle

Notes for I66.0

As CIHI prints them, with any note I66.0 takes from the headings above it.

Includes

Use additional code

Add a code for this detail when the note documents it.

Excludes

Conditions classified elsewhere.

  • When causing cerebral infarction (I63.-)From I66 Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
  • Transient cerebral ischaemic attacks and related syndromes (G45.-)traumatic intracranial haemorrhage (S06.-)vascular dementia (F01.-)From I60-I69 Cerebrovascular diseases
  • Certain:• conditions originating in the perinatal period (P00-P96)• infectious and parasitic diseases (A00-B99)complications of pregnancy, childbirth and the puerperium (O00-O99)congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)endocrine, nutritional and metabolic diseases (E00-E90)injury, poisoning and certain other consequences of external causes (S00-T98)neoplasms (C00-D48)symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)systemic connective tissue disorders (M30-M36)transient cerebral ischaemic attacks and related syndromes (G45.-)From Chapter 9: Diseases of the circulatory system (I00-I99)

Where I66.0 sits

  1. 1ChapterChapter 9: Diseases of the circulatory system (I00-I99)
  2. 2Block I60-I69Cerebrovascular diseases
  3. 3Category I66Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
  4. 4Valid code I66.0Occlusion and stenosis of middle cerebral artery

Source and release

Data release
ICD-10-CA · FY 2026–2027
Effective date
Apr 1, 2026
Publisher
CIHI

This page is built from the ICD-10-CA catalog that Vero Codes reads when it suggests codes: Canadian Institute for Health Information’s FY 2026–2027 release, imported from the publisher’s file and checked against it. The description, notes and structured data come from the same record.

See I66.0 in the CIHI source

Frequently asked questions

What does ICD-10-CA code I66.0 mean?

I66.0 is the ICD-10-CA code for “Occlusion and stenosis of middle cerebral artery” in CIHI’s ICD-10-CA FY 2026–2027 release.

Where is I66.0 in ICD-10-CA?

I66.0 sits under I66 Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction, within I60-I69 Cerebrovascular diseases, within Chapter 9: Diseases of the circulatory system (I00-I99).

What coding notes apply to I66.0?

ICD-10-CA lists Includes, Use additional code, Excludes notes for I66.0, including those from the headings it sits under. They are listed on this page with where each one comes from.

Which ICD-10-CA release does this page use?

It uses CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026 to Mar 31, 2027. It is a reference: confirm the code against the current list and the payer’s rules before you submit it.

Codes beside I66.0

I66.1Occlusion and stenosis of anterior cerebral arteryI66.2Occlusion and stenosis of posterior cerebral arteryI66.3Occlusion and stenosis of cerebellar arteriesI66.4Occlusion and stenosis of multiple and bilateral cerebral arteriesI66.8Occlusion and stenosis of other cerebral arteryI66.9Occlusion and stenosis of unspecified cerebral artery