I66.9 – Occlusion and stenosis of unspecified cerebral artery

ICD-10-CM 2027 diagnosis code · Cerebrovascular diseases

Billable code

ICD-10-CM code I66.9

Code: I66.9 (claims format: I669)
Description: Occlusion and stenosis of unspecified cerebral artery
Billable: Yes – valid for HIPAA-covered transactions
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 9. Diseases of the circulatory system (I00-I99)
Block: I60-I69 Cerebrovascular diseases
Parent codes: I66

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

I66 – Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction

Includes:

embolism of cerebral artery
narrowing of cerebral artery
obstruction (complete) (partial) of cerebral artery
thrombosis of cerebral artery

Excludes1 (not coded here):

Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5)

Block I60-I69

Excludes1 (not coded here):

traumatic intracranial hemorrhage (S06.-)

Use additional code:

code to identify presence of:
alcohol abuse and dependence (F10.-)
exposure to environmental tobacco smoke (Z77.22)
history of tobacco dependence (Z87.891)
hypertension (I10-I1A)
occupational exposure to environmental tobacco smoke (Z57.31)
tobacco dependence (F17.-)
tobacco use (Z72.0)

Index terms for I66.9

Entries in the ICD-10-CM alphabetic index that lead to this code:

Related codes in I66

Frequently asked questions

What is ICD-10 code I66.9?

I66.9 is the ICD-10-CM code for occlusion and stenosis of unspecified cerebral artery, in the block I60-I69 (Cerebrovascular diseases).

Is I66.9 a billable code?

Yes. I66.9 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.

What category does I66.9 belong to?

It belongs to category I66 – Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.