G04: Encephalitis, myelitis and encephalomyelitis

Codes under G04 (Encephalitis, myelitis and encephalomyelitis). A ✓ marks a billable (fully specified) code; category codes without a ✓ are not billable on their own.

Code	Description	Billable
G04.0	Acute disseminated encephalitis and encephalomyelitis (ADEM)	—
G04.00	Acute disseminated encephalitis and encephalomyelitis, unspecified	✓
G04.01	Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)	✓
G04.1	Tropical spastic paraplegia	✓
G04.02	Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis	✓
G04.2	Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified	✓
G04.3	Acute necrotizing hemorrhagic encephalopathy	—
G04.8	Other encephalitis, myelitis and encephalomyelitis	—
G04.9	Encephalitis, myelitis and encephalomyelitis, unspecified	—
G04.30	Acute necrotizing hemorrhagic encephalopathy, unspecified	✓
G04.31	Postinfectious acute necrotizing hemorrhagic encephalopathy	✓
G04.32	Postimmunization acute necrotizing hemorrhagic encephalopathy	✓
G04.39	Other acute necrotizing hemorrhagic encephalopathy	✓
G04.81	Other encephalitis and encephalomyelitis	✓
G04.82	Acute flaccid myelitis	✓
G04.89	Other myelitis	✓
G04.90	Encephalitis and encephalomyelitis, unspecified	✓
G04.91	Myelitis, unspecified	✓

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Informational only, not coding or medical advice. Verify against the official ICD-10-CM (FY2026) and your payer's guidelines.

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