ICD-10 Code B01.11 – Varicella encephalitis and encephalomyelitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B01.11 – Varicella encephalitis and encephalomyelitis
What it is
B01.11 identifies neurologic inflammation caused by varicella-zoster infection, involving the brain and sometimes the spinal cord. Use it when documentation states varicella encephalitis, encephalomyelitis, or both.
Clinical signs
Typical features include altered mental status, seizures, focal neurologic deficits, or spinal cord signs after varicella infection. Clinical features vary; refer to documentation.
When to use this code
Use this code when the provider documents encephalitis or encephalomyelitis due to varicella. It fits cases where neurologic involvement is the primary reason for the encounter and the diagnosis is confirmed or clearly stated. Check documentation if the record only notes uncomplicated varicella.
Do not use for
Do not use B01.11 for uncomplicated chickenpox, postvaricella cerebellitis, or other neurologic conditions not documented as encephalitis or encephalomyelitis. If the cause is unclear, check documentation.
Coding tip
Code the varicella neurologic complication only when the provider links the brain or spinal cord involvement to varicella.