ICD-10 Code for Encephalomyelitis
The ICD-10-CM code for encephalomyelitis is G04.90 — Encephalitis and encephalomyelitis, unspecified. This is the code the Alphabetic Index gives for encephalomyelitis with no further qualifier, valid for FY2027 (October 1, 2026 – September 30, 2027).
G04.90 is billable but unspecified. If the documentation names a type, site or cause, one of the more specific codes below is likely expected.
Which encephalomyelitis code should you use?
The Alphabetic Index lists 18 codes under Encephalomyelitis. Which one applies depends on the qualifier documented in the record — the type, site, cause, or associated condition. Find the qualifier below, then verify the code in the Tabular List before using it.
By type
| acute disseminated | G04.00 | Acute disseminated encephalitis and encephalomyelitis, unspecified | |
| acute necrotizing hemorrhagic | G04.30 | Acute necrotizing hemorrhagic encephalopathy, unspecified | |
| equine | A83.9 | Mosquito-borne viral encephalitis, unspecified | |
| in diseases classified elsewhere | G05.3 | Encephalitis and encephalomyelitis in diseases classified elsewhere | |
| myalgic | G93.32 | Myalgic encephalomyelitis/chronic fatigue syndrome | |
| postchickenpox | B01.11 | Varicella encephalitis and encephalomyelitis | |
| postinfectious NEC | G04.01 | Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM) | |
| postmeasles | B05.0 | Measles complicated by encephalitis | |
| postvaccinal | G04.02 | Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis | |
| postvaricella | B01.11 | Varicella encephalitis and encephalomyelitis | |
| rubella | B06.01 | Rubella encephalitis | |
| specified NEC | G04.81 | Other encephalitis and encephalomyelitis | |
| Venezuelan equine | A92.2 | Venezuelan equine fever |
Encephalomyelitis acute disseminated
| infectious | G04.01 | Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM) | |
| noninfectious | G04.81 | Other encephalitis and encephalomyelitis | |
| postimmunization | G04.02 | Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis | |
| postinfectious | G04.01 | Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM) |
Encephalomyelitis acute necrotizing hemorrhagic
Encephalomyelitis equine
Encephalomyelitis myalgic
| chronic fatigue syndrome [ME/CFS] | G93.32 | Myalgic encephalomyelitis/chronic fatigue syndrome |
Index terms and codes are reproduced from the official ICD-10-CM FY2027 release. The Alphabetic Index is a finding aid — a code must always be verified in the Tabular List before it is reported. Data sources