ICD-10 Code I66 – Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I66 – Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
What it is
This code identifies narrowing or blockage of a cerebral artery without documented brain infarction. Use it when the record shows reduced blood flow in a brain artery, but no stroke or infarct is reported.
Clinical signs
Findings may include neurologic symptoms related to transient or chronic reduced cerebral perfusion. Clinical features vary; refer to documentation for the affected artery, imaging results, and whether infarction is excluded.
When to use this code
Use I66 when the provider documents occlusion or stenosis of a cerebral artery and specifically states that cerebral infarction did not occur. It may apply after vascular imaging or specialist assessment identifies arterial narrowing without stroke.
Choose this code when the diagnosis is confirmed in the chart, not merely suspected. If the note suggests infarction, transient ischemic attack, or another cerebrovascular event, review the documentation before coding.
Do not use for
Do not use I66 for cerebral infarction, hemorrhagic stroke, or nonspecific cerebrovascular symptoms alone. Check documentation if the record does not clearly distinguish stenosis from infarction.
Coding tip
Confirm the exact artery involved and the absence of infarction in the provider’s final diagnosis before assigning I66.