2026 ICD-10-CM Diagnosis Code G37.4Subacute necrotizing myelitis of central nervous system

ICD-10-CM Codes›G00–G99›G35-G37›G37

ICD-10-CM G37.4
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G37.4 is a billable ICD-10-CM diagnosis code for subacute necrotizing myelitis of central nervous system. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 974 through 976. Coders also document this condition as acute necrotizing myelitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (neither hereditary nor degenerative).

Code Identity

ICD-10-CM Code
G37.4
Billable Status
Yes — Valid for Submission
Code Describes
Subacute necrotizing myelitis of central nervous system
Short Description
Subacute necrotizing myelitis of central nervous system
Same as the full description in the CMS dataset.
Parent Code
G37
Other demyelinating diseases of central nervous system

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG35-G37Demyelinating diseases of the central nervous system
CategoryG37Other demyelinating diseases of central nervous system
This CodeG37.4Subacute necrotizing myelitis of central nervous system

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute necrotizing myelitis
  • Demyelination of spinal cord
  • Subacute necrotizing myelitis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Myelitis(acute) (ascending) (childhood) (chronic) (descending) (diffuse) (disseminated) (idiopathic) (pressure) (progressive) (spinal cord) (subacute)
      • necrotizing, subacute

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS020
Other nervous system disorders (neither hereditary nor degenerative)
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Degenerative Nerve Diseases

Degenerative nerve diseases affect many of your body's activities, such as balance, movement, talking, breathing, and heart function. Many of these diseases are genetic. Sometimes the cause is a medical condition such as alcoholism, a tumor, or a stroke. Other causes may include toxins, chemicals, and viruses.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G37.4 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
323.9 Encephalitis NOS
Approximate The match is approximate rather than exact.
ICD-9-CM
341.8 Cns demyelination NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G37.4Overview

Is G37.4 (Other demyelinating diseases of central nervous system) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report subacute necrotizing myelitis of central nervous system on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does G37.4 group to?

When subacute necrotizing myelitis of central nervous system is the principal diagnosis on an inpatient stay, it groups to MS-DRG 974, 975, 976, with relative weights from 0.8945 to 2.8860 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of G37.4?

Under the General Equivalence Mappings, subacute necrotizing myelitis of central nervous system converts to ICD-9-CM 323.9 (encephalitis NOS) and 341.8 (cns demyelination NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.