ICD-10 Code G31.86 – Alexander disease (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G31.86 – Alexander disease
What it is
G31.86 identifies Alexander disease, a rare progressive disorder of the brain’s white matter. It is a leukodystrophy that affects the central nervous system and usually worsens over time.
Clinical signs
Clinical features vary; refer to documentation. Common findings include developmental delay or regression, spasticity, seizures, bulbar dysfunction, and enlarged head size in some patients.
When to use this code
Use G31.86 when the provider documents Alexander disease by name or clearly confirms the diagnosis. You may also use it when imaging or specialist notes support the diagnosis and the record links the patient’s neurologic findings to Alexander disease.
Do not guess from nonspecific white matter disease alone. If the chart only says leukodystrophy or progressive neurologic decline, check documentation for the exact diagnosis before coding.
Do not use for
Do not use this code for other leukodystrophies, nonspecific demyelinating disease, or undefined cerebral degeneration. Check documentation if the provider has not specifically named Alexander disease.
Coding tip
Code G31.86 only when the diagnosis is clearly stated or definitively supported in the record; otherwise, query for clarification.