ICD-10 Code G04 – Encephalitis, myelitis and encephalomyelitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G04 – Encephalitis, myelitis and encephalomyelitis
What it is
Code G04 identifies inflammatory disorders of the brain, spinal cord, or both. Use it when documentation supports encephalitis, myelitis, or encephalomyelitis, without a more specific cause or subtype.
Clinical signs
Clinical features may include altered mental status, focal neurologic deficits, weakness, sensory changes, or gait problems. Clinical features vary; refer to documentation and any confirmed neurologic findings.
When to use this code
Use G04 when the provider documents a nonspecific inflammatory condition involving the brain or spinal cord and does not name a more specific infectious, autoimmune, or demyelinating diagnosis. It may also fit when records describe encephalomyelitis or myelitis as the final diagnosis. Check documentation if the cause is unclear.
Do not use for
Do not use this code if the chart specifies a different primary diagnosis, such as a defined infection, demyelinating disease, or postinfectious condition. Do not use it when the documentation only mentions symptoms without a confirmed inflammatory disorder.
Coding tip
Confirm whether the provider identified a specific etiology or site, because a more detailed code may be required.