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ICD-10-CM 2027

ICD-10 code for acute disseminated encephalomyelitis

G04.00

Acute disseminated encephalitis and encephalomyelitis, unspecified

From the official ICD-10-CM alphabetic index entry “Encephalomyelitis › acute disseminated”. Page updated September 29, 2026.

About coding acute disseminated encephalomyelitis

The ICD-10-CM code for acute disseminated encephalomyelitis is G04.00 (Acute disseminated encephalitis and encephalomyelitis, unspecified). The official index lists 4 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on G04.00.

Within G04.0, choose G04.00 (Acute disseminated encephalitis and encephalomyelitis, unspecified) only when documentation doesn't support a more specific option: postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM) (G04.01) and Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis (G04.02).

As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 023 (Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator, relative weight 5.7444), DRG 024 (Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC, relative weight 3.9708), DRG 097 (Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC, relative weight 3.8226), DRG 098 (Non-Bacterial Infection of Nervous System Except Viral Meningitis with CC, relative weight 2.2706) and DRG 099 (Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCC, relative weight 1.5256), in MDC 01 (Diseases and Disorders of the Nervous System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

More specific acute disseminated encephalomyelitis codes (official index)

  • infectious G04.01 — Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)
  • noninfectious G04.81 — Other encephalitis and encephalomyelitis
  • postimmunization G04.02 — Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis
  • postinfectious G04.01 — Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)

Common questions about acute disseminated encephalomyelitis ICD-10 codes

What is the ICD-10 code for acute disseminated encephalomyelitis?

G04.00 — Acute disseminated encephalitis and encephalomyelitis, unspecified. More specific codes apply when the documentation supports them: G04.01, G04.81, G04.02, G04.01.

What is the ICD-10 code for infectious acute disseminated encephalomyelitis?

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

What is the ICD-10 code for noninfectious acute disseminated encephalomyelitis?

G04.81 — Other encephalitis and encephalomyelitis.

What is the ICD-10 code for postimmunization acute disseminated encephalomyelitis?

G04.02 — Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis.

What is the ICD-10 code for postinfectious acute disseminated encephalomyelitis?

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

Is G04.00 billable?

Yes. G04.00 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can G04.00 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict G04.00 as a principal diagnosis.

Is G04.00 a CC or MCC?

G04.00 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.