G04.00 Acute disseminated encephalitis and encephalomyelitis, unspecified

The ICD-10-CM code for Acute disseminated encephalitis and encephalomyelitis, unspecified is G04.00 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

6: Diseases of the nervous system (G00-G99)

Section

G00-G09: Inflammatory diseases of the central nervous system (G00-G09)

Category G04

19 codes (14 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to G04.00:

• Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) › disseminated, acute
• Encephalomyelitis › acute disseminated
• Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) › acute › disseminated
• Meningoencephalomyelitis › acute NEC (viral) › disseminated

U.S. Hospital Utilization

• An estimated 1,160 U.S. inpatient stays in 2023 included G04.00 among the documented diagnoses.
• 625 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Dominant/nondominant side (TOC entry)

a. Dominant/nondominant side ................................................................................................. 45

Pain - Category G89 (TOC entry)

b. Pain - Category G89.............................................................................................................. 45

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)