ICD-10 Code G46.3 – Brain stem stroke syndrome (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G46.3 – Brain stem stroke syndrome
What it is
G46.3 identifies a brain stem stroke syndrome, meaning neurologic deficits caused by ischemia or infarction affecting the brainstem. Use it for the syndrome, not for the underlying stroke mechanism alone.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include cranial nerve deficits, vertigo, dysarthria, diplopia, ataxia, weakness, or altered consciousness when the brainstem is involved.
When to use this code
Use this code when the provider documents a brain stem stroke syndrome or a stroke syndrome localized to the brainstem. It may support cases with specific brainstem neurologic deficits after imaging or specialist evaluation. If documentation only states acute stroke without localization, check the record for a more specific diagnosis.
Do not use for
Do not use it for general stroke without brainstem involvement, transient symptoms without confirmed stroke syndrome, or unrelated cranial nerve disorders. Check documentation if the location or cause is unclear.
Coding tip
Query for the exact stroke site and syndrome wording when the note mentions posterior circulation or brainstem findings.