G04.91 Myelitis, unspecified

The ICD-10-CM code for Myelitis, unspecified is G04.91 (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 G04.91:

• Myelitis (acute) (ascending) (childhood) (chronic) (descending) (diffuse) (disseminated) (idiopathic) (pressure) (progressive) (spinal cord) (subacute)
• Myeloradiculitis
• Infection, infected, infective (opportunistic) › spinal cord NOS

U.S. Hospital Utilization

• An estimated 1,350 U.S. inpatient stays in 2023 included G04.91 among the documented diagnoses.
• 210 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)