ICD-10 Code G04.9 – Encephalitis, myelitis and encephalomyelitis, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G04.9 – Encephalitis, myelitis and encephalomyelitis, unspecified
What it is
G04.9 identifies an inflammatory disorder affecting the brain, spinal cord, or both when the provider does not specify the exact type. Use it for a documented diagnosis of encephalitis, myelitis, or encephalomyelitis without further detail.
Clinical signs
Clinical features vary; refer to documentation. Findings may include neurologic deficits consistent with central nervous system inflammation, such as altered mental status, weakness, sensory changes, or coordination problems.
When to use this code
Use this code when the record states encephalitis, myelitis, or encephalomyelitis but does not name a specific cause, location, or subtype. It also fits when the clinician documents the condition as unspecified or when available details are insufficient for a more precise code. Check documentation for infectious, autoimmune, or demyelinating causes before assigning G04.9.
Do not use for
Do not use G04.9 if the documentation clearly identifies a more specific encephalitis, myelitis, or encephalomyelitis code. Avoid it when the condition is only suspected, ruled out, or better described by another neurologic diagnosis.
Coding tip
Query for the exact inflammatory site and cause before settling on an unspecified code.