ICD-10 Code I66.02 – Occlusion and stenosis of left middle cerebral artery (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I66.02 – Occlusion and stenosis of left middle cerebral artery
What it is
This code identifies narrowing or blockage of the left middle cerebral artery, a major vessel supplying blood to the left side of the brain. Use it when documentation specifies the left MCA and an occlusive or stenotic process.
Clinical signs
Clinical features vary; refer to documentation. Findings may include neurologic deficits consistent with left hemispheric ischemia, such as speech or language disturbance, right-sided weakness, or sensory changes.
When to use this code
Assign I66.02 when the provider documents occlusion or stenosis of the left middle cerebral artery, with or without associated infarction being separately coded. It is appropriate for imaging-confirmed arterial narrowing or blockage when laterality is clearly stated. Check documentation if the record describes cerebrovascular disease without specifying the vessel.
Do not use for
Do not use this code for generalized stroke, transient ischemic attack, or carotid artery disease unless the left middle cerebral artery is specifically involved. Check documentation when the chart only states cerebral atherosclerosis or embolism without exact vessel detail.
Coding tip
Verify laterality and whether the condition is occlusion, stenosis, or both before assigning the code.