G04.01

Billable
ChapterG00–G99
Ranksubcategory
Official Description

Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)

Metadata & Insights
  • •2026 ICD-10-CM Edition - Effective October 1, 2025.
  • •Billable/specific code (valid for reimbursement).
  • •Chapter 6: Diseases of the Nervous System (G00-G99).

Instructional Notes

Excludes1(Not coded here)
  • post chickenpox encephalitis (B01.1)
  • post measles encephalitis (B05.0)
  • post measles myelitis (B05.1)
General instructions are available for the parent sections:
View CH6 NotesView G04 NotesView G04.0 Notes

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)
G04.01Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to G04.01:

subcategoryG04.0
Acute disseminated encephalitis and encephalomyelitis (ADEM)
View context instructions
categoryG04
Encephalitis, myelitis and encephalomyelitis
View context instructions
chapterCH6
Diseases of the nervous system (G00-G99)
View context instructions

Alphabetic Index Mentions

These are Diagnosis Index lookup paths that route to G04.01. Use them as entry terms for search, then confirm final coding instructions in the Tabular List and notes above.

8 raw paths
Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)3 unique routes
acute(2 variants)
disseminated(2 variants)
infectious→G04.01
postinfectious→G04.01
postinfectious NEC→G04.01
Encephalomyelitis3 unique routes
acute disseminated(2 variants)
infectious→G04.01
postinfectious→G04.01
postinfectious NEC→G04.01
Leukoencephalitis1 unique routes
postinfectious→G04.01
Meningoencephalomyelitis1 unique routes
acute NEC (viral)
disseminated
postinfectious→G04.01

MS-DRG Classification

2026 v43.1

This code is grouped within the following Diagnosis Related Group(s) for clinical reimbursement:

DRG 023
Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator
DRG 024
Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC
DRG 097
Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC
DRG 098
Non-Bacterial Infection of Nervous System Except Viral Meningitis with CC
DRG 099
Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCC

Cross Reference

Find Procedures (ICD-10-PCS)

Find surgical and procedural codes related to Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM).

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