G04

Non-Billable

ChapterG00–G99

Rankcategory

Official Description

Encephalitis, myelitis and encephalomyelitis

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).

CH6 Parent Instructions

Excludes2(Not included here)

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)

Instructional Notes

Includes

acute ascending myelitis
meningoencephalitis
meningomyelitis

Excludes1(Not coded here)

encephalopathy NOS (G93.40)

Excludes2(Not included here)

acute transverse myelitis (G37.3)
alcoholic encephalopathy (G31.2)
multiple sclerosis (G35-)
myalgic encephalomyelitis (G93.32)
subacute necrotizing myelitis (G37.4)
toxic encephalitis (G92.8)
toxic encephalopathy (G92.8)

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)

G04.1Tropical spastic paraplegia

G04.2Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified

G04.3Acute necrotizing hemorrhagic encephalopathy

G04.8Other encephalitis, myelitis and encephalomyelitis

G04.9Encephalitis, myelitis and encephalomyelitis, unspecified

Applicable Ancestor Context

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

chapterCH6

Diseases of the nervous system (G00-G99)

View context instructions

Alphabetic Index Mentions

These are Diagnosis Index lookup paths that route to G04. 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

myelitis→G04

Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)19 unique routes

Direct index entry→G04

acute(9 variants)

disseminated→G04(5 variants)

infectious→G04

noninfectious→G04

postimmunization (postvaccination)→G04