G04
Encephalitis, myelitis and encephalomyelitis
G04 is a non-billable ICD-10-CM code category for encephalitis, myelitis and encephalomyelitis. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are G04.0 Acute disseminated encephalitis and encephalomyelitis (ADEM); G04.1 Tropical spastic paraplegia; G04.2 Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified; G04.3 Acute necrotizing hemorrhagic encephalopathy and 2 more. Its coding notes include 1 Excludes1 entry and 15 Excludes2 entries.
Excludes1
Not coded here. The listed conditions generally should not be reported together.
- encephalopathy NOS (G93.40)
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (8 notes)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Includes
Further defines or gives examples of the content of the category.
- acute ascending myelitis
- meningoencephalitis
- meningomyelitis
More specific codes under G04 6
- G04.0Acute disseminated encephalitis and encephalomyelitis (ADEM)Header
- G04.1Tropical spastic paraplegiaBillable
- G04.2Bacterial meningoencephalitis and meningomyelitis, not elsewhere classifiedBillable
- G04.3Acute necrotizing hemorrhagic encephalopathyHeader
- G04.8Other encephalitis, myelitis and encephalomyelitisHeader
- G04.9Encephalitis, myelitis and encephalomyelitis, unspecifiedHeader