ICD10
ICD-10 Code G04.9: Encephalitis, myelitis and encephalomyelitis, unspecified
Reviewed by HealthAssure Clinical TeamUpdated 26 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, unspecified 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
category
G04Encephalitis, myelitis and encephalomyelitis
currentG04
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
Related codes
Sibling codes
Mapped diagnoses and classifications
SNOMED_CT 8528005high
Acute ascending myelitis
Source: SNOMED International ICD-10 map
SNOMED_CT 897031002high
Acute flaccid myelitis
Source: SNOMED International ICD-10 map
SNOMED_CT 1259084000high
Autoimmune movement disorder
Source: SNOMED International ICD-10 map
SNOMED_CT 129132000high
Bacterial infectious disease of brain
Source: SNOMED International ICD-10 map
SNOMED_CT 45170000high
Encephalitis
Source: SNOMED International ICD-10 map
SNOMED_CT 267576008high
Encephalitis, myelitis and encephalomyelitis
Source: SNOMED International ICD-10 map
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
G04.9
Replacement codes
G04.90 — Encephalitis and encephalomyelitis, unspecifiedG04.91 — Myelitis, unspecified
Common synonyms
Encephalitis, myelitis and encephalomyelitis, unspecifiedEncephalitis, 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.