ICD-10 Code I66.9 – Occlusion and stenosis of unspecified cerebral artery (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I66.9 – Occlusion and stenosis of unspecified cerebral artery
What it is
This code identifies narrowing or blockage of a cerebral artery when the specific artery is not documented. Use it for an intracranial arterial obstruction affecting brain blood flow, but not tied to a named vessel.
Clinical signs
Patients may present with neurologic deficits such as weakness, speech difficulty, facial droop, or sudden confusion. Clinical features vary; refer to documentation and imaging reports when available.
When to use this code
Use I66.9 when the record confirms cerebral artery occlusion or stenosis but does not specify the artery involved. It may appear in stroke or transient ischemic attack workups, vascular imaging findings, or discharge summaries. Verify that the documentation refers to an intracranial cerebral artery, not an extracranial vessel.
Do not use for
Do not use this code for carotid or vertebral artery disease, or when a more specific cerebral artery is named. Check documentation if the record describes infarction without clear stenosis or occlusion.
Coding tip
Code the highest level of specificity documented, and query the provider if the affected cerebral artery is named but missing from the record.