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G04 ICD-10-CM Code: Encephalitis, myelitis and encephalomyelitis

A clear reference for the official code description, hierarchy, and related coding information from the FY 2027 U.S. release.

Official description

G04

Encephalitis, myelitis and encephalomyelitis

ICD-10-CM diagnosis code · United States clinical modification

Where G04 sits

  1. 1

    Chapter 6

    Diseases of the nervous system (G00-G99)

  2. 2

    Section

    Inflammatory diseases of the central nervous system (G00-G09)

  3. 3

    Category G04

    Encephalitis, myelitis and encephalomyelitis

  4. 4

    Code G04

    Encephalitis, myelitis and encephalomyelitis

Codes under G04

G04 is a non-billable category. Choose the child code that best matches the documented diagnosis.

G04.0Acute disseminated encephalitis and encephalomyelitis (ADEM)G04.1Tropical spastic paraplegiaG04.2Bacterial meningoencephalitis and meningomyelitis, not elsewhere classifiedG04.3Acute necrotizing hemorrhagic encephalopathyG04.8Other encephalitis, myelitis and encephalomyelitisG04.9Encephalitis, myelitis and encephalomyelitis, unspecified

Notes for this code

Inclusion terms

No inclusion terms are listed for G04.

Code first

No “code first” instruction is listed for G04.

Use additional code

No “use additional code” instruction is listed for G04.

Excludes1

Conditions that should not be reported together with this code.

  • encephalopathy NOS (G93.40)

Excludes2

Conditions not included here that may be reported separately when present.

  • 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)

Source and release

Data release
U.S. ICD-10-CM · FY 2027
Effective date
Oct 1, 2026

This reference is generated from Vero’s ICD-10-CM description, hierarchy, and code-note dataset. The visible content and structured data share that source.

Review the CDC/NCHS ICD-10-CM source

Frequently asked questions

What does ICD-10-CM code G04 mean?

G04 is the FY 2027 U.S. ICD-10-CM code for “Encephalitis, myelitis and encephalomyelitis.”

Is G04 a billable or specific ICD-10-CM code?

No. G04 has more specific child codes in the FY 2027 reference data. Select the code that matches the documentation and confirm the active code set and payer requirements.

Where is G04 located in ICD-10-CM?

G04 is listed in Chapter 6, Diseases of the nervous system (G00-G99), within Inflammatory diseases of the central nervous system (G00-G09) (G00–G09), under category G04, Encephalitis, myelitis and encephalomyelitis.

What coding notes are listed for G04?

No inclusion terms are listed for G04 in this reference record. No code-first instruction is listed. Excludes1 notes: encephalopathy NOS (G93.40). Excludes2 notes: 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).