ICD-10 Code I67.5 – Moyamoya disease (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I67.5 – Moyamoya disease
What it is
I67.5 identifies moyamoya disease, a rare cerebrovascular disorder marked by progressive narrowing of arteries at the base of the brain. It can reduce blood flow and increase the risk of stroke or transient ischemic attacks.
Clinical signs
Clinical features vary; refer to documentation. Common findings include recurrent ischemic events, headaches, seizures, or neurologic deficits related to reduced cerebral perfusion. Imaging may show characteristic collateral vessel formation.
When to use this code
Use I67.5 when the provider documents moyamoya disease or a confirmed diagnosis of this condition. Assign it for encounters focused on the disease itself, including evaluation of neurologic symptoms linked to moyamoya. If the record only suggests moyamoya without confirmation, check documentation before coding.
Do not use for
Do not use this code for nonspecific cerebrovascular disease or stroke without documented moyamoya disease. Do not assign it when the chart mentions only vascular narrowing and the diagnosis remains unconfirmed.
Coding tip
Code I67.5 only when the diagnosis is clearly stated; otherwise, query the provider for confirmation.