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ICD-10 Code G04.01: Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)

G04.01 is a billable ICD-10 diagnosis code used to classify Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM) in medical records and claims. You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records. ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the nervous system (G00-G99).

Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026

What is this code?

ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. 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 postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious adem) in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code can be used as a clinically usable diagnosis entry in standardized coding workflows.

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.

Code hierarchy

chapter
6Diseases of the nervous system (G00-G99)
block
G00-G09Inflammatory diseases of the central nervous system
category
G04Encephalitis, myelitis and encephalomyelitis
category
G04.0Acute disseminated encephalitis and encephalomyelitis (ADEM)
currentG04.0

Official coding notes

Excludes1 (do not code together)
  • post chickenpox encephalitis (B01.1)
  • post measles encephalitis (B05.0)
  • post measles myelitis (B05.1)

Where you may see this code

You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.

Related specialists

NeurologistGeneral Physician

Coverage-related procedures and services

CPT 87483high
INFECTIOUS AGENT DETECTION BY NUCLEIC ACID (DNA OR RNA); CENTRAL NERVOUS SYSTEM PATHOGEN (EG, NEISSERIA MENINGITIDIS, STREPTOCOCCUS PNEUMONIAE, LISTERIA, HAEMOPHILUS INFLUENZAE, E. COLI, STREPTOCOCCUS AGALACTIAE, ENTEROVIRUS, HUMAN PARECHOVIRUS, HERPES SIMPLEX VIRUS TYPE 1 AND 2, HUMAN HERPESVIRUS 6, CYTOMEGALOVIRUS, VARICELLA ZOSTER VIRUS, CRYPTOCOCCUS), INCLUDES MULTIPLEX REVERSE TRANSCRIPTION, WHEN PERFORMED, AND MULTIPLEX AMPLIFIED PROBE TECHNIQUE, MULTIPLE TYPES OR SUBTYPES, 12-25 TARGETS
Source: CMS coverage guidance
CPT 92083high
VISUAL FIELD EXAMINATION, UNILATERAL OR BILATERAL, WITH INTERPRETATION AND REPORT; EXTENDED EXAMINATION (EG, GOLDMANN VISUAL FIELDS WITH AT LEAST 3 ISOPTERS PLOTTED AND STATIC DETERMINATION WITHIN THE CENTRAL 30 DEG, OR QUANTITATIVE, AUTOMATED THRESHOLD PERIMETRY, OCTOPUS PROGRAM G-1, 32 OR 42, HUMPHREY VISUAL FIELD ANALYZER FULL THRESHOLD PROGRAMS 30-2, 24-2, OR 30/60-2)
Source: CMS coverage guidance
CPT 92082high
VISUAL FIELD EXAMINATION, UNILATERAL OR BILATERAL, WITH INTERPRETATION AND REPORT; INTERMEDIATE EXAMINATION (EG, AT LEAST 2 ISOPTERS ON GOLDMANN PERIMETER, OR SEMIQUANTITATIVE, AUTOMATED SUPRATHRESHOLD SCREENING PROGRAM, HUMPHREY SUPRATHRESHOLD AUTOMATIC DIAGNOSTIC TEST, OCTOPUS PROGRAM 33)
Source: CMS coverage guidance
CPT 92081high
VISUAL FIELD EXAMINATION, UNILATERAL OR BILATERAL, WITH INTERPRETATION AND REPORT; LIMITED EXAMINATION (EG, TANGENT SCREEN, AUTOPLOT, ARC PERIMETER, OR SINGLE STIMULUS LEVEL AUTOMATED TEST, SUCH AS OCTOPUS 3 OR 7 EQUIVALENT)
Source: CMS coverage guidance
CPT 72126high
COMPUTED TOMOGRAPHY, CERVICAL SPINE; WITH CONTRAST MATERIAL
Source: CMS coverage guidance
CPT 72125high
COMPUTED TOMOGRAPHY, CERVICAL SPINE; WITHOUT CONTRAST MATERIAL
Source: CMS coverage guidance

Coding guidelines

Common synonyms

Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)Postinfectious acute disseminated encephalitis and encephalomyelitisPostinfectious acute disseminated encephalitis and encephalomyelitis postinfectious ADEM

Frequently asked questions

Code details

CodeG04.01
SystemICD10
Display namePostinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)
ChapterDiseases of the nervous system (G00-G99)
BlockInflammatory diseases of the central nervous system

Flags

BillableYes
Valid clinical useYes

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

Index terms

Matched terms
Encephalitis(chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)Encephalitis(chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)Encephalitis(chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)EncephalomyelitisEncephalomyelitisEncephalomyelitisLeukoencephalitisMeningoencephalomyelitis

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.