ICD-10 Code I63.21 – Cerebral infarction due to unspecified occlusion or stenosis of vertebral arteries (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I63.21 – Cerebral infarction due to unspecified occlusion or stenosis of vertebral arteries
What it is
This code identifies an ischemic stroke caused by reduced or blocked blood flow in a vertebral artery, with the side and exact vessel narrowing or occlusion not specified. Use it when the infarction is documented as due to vertebral artery disease.
Clinical signs
Clinical features vary; refer to documentation. Vertebrobasilar stroke may present with dizziness, gait imbalance, visual disturbance, dysarthria, or other focal neurologic deficits, and imaging typically confirms cerebral infarction.
When to use this code
Use I63.21 when the provider documents cerebral infarction from unspecified occlusion or stenosis of a vertebral artery. It fits cases where the stroke is linked to vertebral artery disease but the record does not identify a more specific artery or laterality. Check documentation if the cause is described only as embolic, thrombotic, or unspecified stroke without vertebral artery involvement.
Do not use for
Do not use this code for hemorrhagic stroke, transient ischemic attack, or cerebral infarction from a clearly different vessel. If the record specifies a different occlusion site or laterality, code that more specific diagnosis instead.
Coding tip
Match the code to the documented artery and laterality; if vertebral artery stenosis or occlusion is not stated, check documentation before assigning I63.21.