G04.0

Non-Billable
ChapterG00–G99
Ranksubcategory
Official Description

Acute disseminated encephalitis and encephalomyelitis (ADEM)

Metadata & Insights
  • •2026 ICD-10-CM Edition - Effective October 1, 2025.
  • •Non-billable category (requires more specific sub-code).
  • •Chapter 6: Diseases of the Nervous System (G00-G99).

Instructional Notes

Excludes1(Not coded here)
  • acute necrotizing hemorrhagic encephalopathy (G04.3-)
  • other noninfectious acute disseminated encephalomyelitis (noninfectious ADEM) (G04.81)
General instructions are available for the parent sections:
View CH6 NotesView G04 Notes

Clinical Hierarchy

CH6Diseases of the nervous system (G00-G99)
G00-G09Inflammatory diseases of the central nervous system (G00-G09)
G04Encephalitis, myelitis and encephalomyelitis
G04.0Acute disseminated encephalitis and encephalomyelitis (ADEM)
G04.00Acute disseminated encephalitis and encephalomyelitis, unspecified
G04.01Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)
G04.02Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to G04.0:

categoryG04
Encephalitis, myelitis and encephalomyelitis
View context instructions
chapterCH6
Diseases of the nervous system (G00-G99)
View context instructions

Alphabetic Index Mentions

These are Diagnosis Index lookup paths that route to G04.0. Use them as entry terms for search, then confirm final coding instructions in the Tabular List and notes above.

25 raw paths
Complication (s) (from) (of)2 unique routes
vaccination(2 variants)
encephalitis or encephalomyelitis→G04.0
myelitis→G04.0
Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)10 unique routes
acute(4 variants)
disseminated→G04.0(4 variants)
infectious→G04.0
postimmunization (postvaccination)→G04.0
postinfectious→G04.0
disseminated, acute→G04.0
due to
smallpox inoculation→G04.0
following vaccination or other immunization procedure→G04.0
postimmunization→G04.0
postinfectious NEC→G04.0
postvaccinal→G04.0
Encephalomyelitis6 unique routes
acute disseminated→G04.0(4 variants)
infectious→G04.0
postimmunization→G04.0
postinfectious→G04.0
postinfectious NEC→G04.0
postvaccinal→G04.0
Encephalopathy (acute)1 unique routes
in (due to) (with)
vaccination→G04.0
Leukoencephalitis2 unique routes
acute (subacute) hemorrhagic
postimmunization or postvaccinal→G04.0
postinfectious→G04.0
Leukoencephalopathy1 unique routes
postimmunization and postvaccinal→G04.0
Meningoencephalomyelitis3 unique routes
acute NEC (viral)(3 variants)
disseminated→G04.0(3 variants)
postimmunization or postvaccination→G04.0
postinfectious→G04.0

MS-DRG Classification

2026

No direct MS-DRG triggers identified.

Cross Reference

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