What does ICD-10 code G04 mean?

ICD-10 code G04 is the standardized code used for encephalitis, myelitis and encephalomyelitis in medical records and coding systems.

When is ICD-10 code G04 used?

Doctors, hospitals, and insurers may use ICD-10 code G04 when recording encephalitis, myelitis and encephalomyelitis in a standardized format. This entry may also act as a broader category that points toward more specific child codes.

Does ICD-10 code G04 confirm a diagnosis?

No. A code helps standardize documentation and claims, but it should not be read as a substitute for a clinician's full assessment.

ICD10

ICD-10 Code G04: Encephalitis, myelitis and encephalomyelitis

Name: ICD-10 Code G04: Encephalitis, myelitis and encephalomyelitis
Creator: HealthAssure Clinical Team
Published: 2026-05-21T06:06:44.344Z

G04 is an ICD-10 diagnosis entry used to group records related to Encephalitis, myelitis and encephalomyelitis. You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen. ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Diseases of the nervous system (G00-G99).

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Diseases of the nervous system (G00-G99).

When is it used?

May be used when a clinician documents encephalitis, myelitis and encephalomyelitis in a patient's medical record.
May appear in hospital records, claims, referrals, and clinical documentation.
This code may act more like a grouping or parent code, so a more specific child code may be used in final documentation when available.

What it does not mean

A code alone does not explain severity, treatment plan, or outcome.
A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
This entry may represent a broader category rather than the most specific billable code.

Code hierarchy

chapter

6Diseases of the nervous system (G00-G99)

block

G00-G09Inflammatory diseases of the central nervous system

currentG00-G09

Official coding notes

Includes

acute ascending myelitis
meningoencephalitis
meningomyelitis

Excludes1 (do not code together)

encephalopathy NOS (G93.40)

Excludes2 (may code together if documented)

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)

Where you may see this code

You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen.

Related specialists

NeurologistGeneral Physician

Sibling codes

G00Bacterial meningitis, not elsewhere classified G01Meningitis in bacterial diseases classified elsewherebillable G02Meningitis in other infectious and parasitic diseases classified elsewherebillable G03Meningitis due to other and unspecified causes G05Encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere G06Intracranial and intraspinal abscess and granuloma G07Intracranial and intraspinal abscess and granuloma in diseases classified elsewherebillable G08Intracranial and intraspinal phlebitis and thrombophlebitisbillable G09Sequelae of inflammatory diseases of central nervous systembillable

Coding guidelines

Compatibility

Legacy code aligns to an official FY 2026 category. Frontend should resolve to the official category page and surface the billable child codes.

Legacy codes

G04

Replacement codes

G04.1 — Tropical spastic paraplegiaG04.2 — Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified

Common synonyms

Encephalitis, myelitis and encephalomyelitis

Frequently asked questions

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.