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

Compare with another code for G37.4Check this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 72 · RxHCC V08 category 155

What these terms mean →

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

The tabular list publishes no instructional note for this code itself.

Where it sits Source: CMS/NCHS

Under:Chapter 6: Diseases of the Nervous SystemG35-G37 Demyelinating diseases of the central nervous systemG37 Other demyelinating diseases of central nervous system

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 023 — CRANIOTOMY WITH MAJOR DEVICE IMPLANT OR ACUTE COMPLEX CNS PRINCIPAL DIAGNOSIS WITH MCC OR ANTINEOPLASTIC IMPLANT OR EPILEPSY WITH NEUROSTIMULATOR (MDC 01)
  • MS-DRG 024 — CRANIOTOMY WITH MAJOR DEVICE IMPLANT OR ACUTE COMPLEX CNS PRINCIPAL DIAGNOSIS WITHOUT MCC (MDC 01)
  • MS-DRG 097 — NON-BACTERIAL INFECTION OF NERVOUS SYSTEM EXCEPT VIRAL MENINGITIS WITH MCC (MDC 01)
  • MS-DRG 098 — NON-BACTERIAL INFECTION OF NERVOUS SYSTEM EXCEPT VIRAL MENINGITIS WITH CC (MDC 01)
  • MS-DRG 099 — NON-BACTERIAL INFECTION OF NERVOUS SYSTEM EXCEPT VIRAL MENINGITIS WITHOUT CC/MCC (MDC 01)
  • MS-DRG 974 — HIV WITH MAJOR RELATED CONDITION WITH MCC (MDC 25)
  • MS-DRG 975 — HIV WITH MAJOR RELATED CONDITION WITH CC (MDC 25)
  • MS-DRG 976 — HIV WITH MAJOR RELATED CONDITION WITHOUT CC/MCC (MDC 25)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 182 — Spinal Cord Disorders/Injuries

Other models: CMS-HCC V22 HCC 72 · RxHCC V08 HCC 155

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Don’t confuse G37.4 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of G37.4 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • G37.9— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Demyelinating disease of central nervous system, unspecified” takes G37.9; specificity in the record moves it back here.

    Full comparison: G37.4 vs G37.9 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Subacute necrotizing myelitis of central nervous system is a billable ICD-10-CM diagnosis code (G37.4).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • MCC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name G37.4 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes2 note: G04 — Encephalitis, myelitis and encephalomyelitis.

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: MCC — Major Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 191 clinically related codes on its CMS exclusion list. Does not count toward severity when the stay groups to DRGs 974-976 (HIV with Major Related Condition).

Named in the grouper logic of 8 MS-DRGs: DRG 023 (MDC 01), DRG 024 (MDC 01), DRG 097 (MDC 01), DRG 098 (MDC 01), DRG 099 (MDC 01), DRG 974 (MDC 25), DRG 975 (MDC 25), DRG 976 (MDC 25).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NVS020 — Other nervous system disorders (neither hereditary nor degenerative) (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as MCC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

B75 — Trichinellosis, G04.00 — Acute disseminated encephalitis and encephalomyelitis, unspecified, G04.01 — Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM), G04.31 — Postinfectious acute necrotizing hemorrhagic encephalopathy, G04.81 — Other encephalitis and encephalomyelitis, G04.82 — Acute flaccid myelitis, G04.89 — Other myelitis, G04.90 — Encephalitis and encephalomyelitis, unspecified, G04.91 — Myelitis, unspecified, G37.0 — Diffuse sclerosis of central nervous system, G37.5 — Concentric sclerosis [Balo] of central nervous system, H66.40 — Suppurative otitis media, unspecified, unspecified ear, H66.41 — Suppurative otitis media, unspecified, right ear, H66.42 — Suppurative otitis media, unspecified, left ear, H66.43 — Suppurative otitis media, unspecified, bilateral, J09.X3 — Influenza due to identified novel influenza A virus with gastrointestinal manifestations, J09.X9 — Influenza due to identified novel influenza A virus with other manifestations, J10.2 — Influenza due to other identified influenza virus with gastrointestinal manifestations, J10.81 — Influenza due to other identified influenza virus with encephalopathy, J10.82 — Influenza due to other identified influenza virus with myocarditis, +170 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Spinal Cord Disorders/Injuries) for risk-adjusted payment.

B02.24 — Postherpetic myelitis, G04.1 — Tropical spastic paraplegia, G04.82 — Acute flaccid myelitis, G04.89 — Other myelitis, G04.91 — Myelitis, unspecified, G05.4 — Myelitis in diseases classified elsewhere, G14 — Postpolio syndrome, G32.0 — Subacute combined degeneration of spinal cord in diseases classified elsewhere, G32.81 — Cerebellar ataxia in diseases classified elsewhere, G37.3 — Acute transverse myelitis in demyelinating disease of central nervous system, G83.4 — Cauda equina syndrome, G90.1 — Familial dysautonomia [Riley-Day], G95.0 — Syringomyelia and syringobulbia, G95.11 — Acute infarction of spinal cord (embolic) (nonembolic), G95.19 — Other vascular myelopathies, G95.20 — Unspecified cord compression, G95.29 — Other cord compression, G95.81 — Conus medullaris syndrome, G95.89 — Other specified diseases of spinal cord, G95.9 — Disease of spinal cord, unspecified, +230 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Quadriplegia, Paraplegia

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other nervous system disorders (neither hereditary nor degenerative)).

G13.2 — Systemic atrophy primarily affecting the central nervous system in myxedema, G13.8 — Systemic atrophy primarily affecting central nervous system in other diseases classified elsewhere, G36.0 — Neuromyelitis optica [Devic], G36.1 — Acute and subacute hemorrhagic leukoencephalitis [Hurst], G36.8 — Other specified acute disseminated demyelination, G36.9 — Acute disseminated demyelination, unspecified, G37.0 — Diffuse sclerosis of central nervous system, G37.1 — Central demyelination of corpus callosum, G37.2 — Central pontine myelinolysis, G37.3 — Acute transverse myelitis in demyelinating disease of central nervous system, G37.5 — Concentric sclerosis [Balo] of central nervous system, G37.8 — Other specified demyelinating diseases of central nervous system, G37.81 — Myelin oligodendrocyte glycoprotein antibody disease, G37.89 — Other specified demyelinating diseases of central nervous system, G37.9 — Demyelinating disease of central nervous system, unspecified, G46.0 — Middle cerebral artery syndrome, G46.1 — Anterior cerebral artery syndrome, G46.2 — Posterior cerebral artery syndrome, G46.3 — Brain stem stroke syndrome, G46.4 — Cerebellar stroke syndrome, +97 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Myelitis”; these codes share that main term but sit in a different category of the Tabular List.

A17.82 — Tuberculous meningoencephalitis (tuberculous), A52.14 — Late syphilitic encephalitis (syphilitic), B00.82 — Herpes simplex myelitis (herpes simplex), B01.12 — Varicella myelitis (varicella), B02.24 — Postherpetic myelitis (postherpetic), G04.02 — Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis (postvaccinal), G04.82 — Acute flaccid myelitis (flaccid), G04.89 — Other myelitis (specified NEC), G04.91 — Myelitis, unspecified, G05.4 — Myelitis in diseases classified elsewhere (in diseases classified elsewhere), G36.0 — Neuromyelitis optica [Devic] (optic neuritis in), G92.9 — Unspecified toxic encephalopathy (toxic)

Contextual Map

Every relationship of G37.4 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run G37.4 with this related code in Claim Check

Hierarchy

Referenced by Excludes2 notes

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 182 — Spinal Cord Disorders/Injuries [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 8,919 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027
  • MDC 25 — Human Immunodeficiency Virus Infections[MDC crossing]: “Human Immunodeficiency Virus Infections — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Myelitis (acute) (ascending) (childhood) (chronic) (descending) (diffuse) (disseminated) (idiopathic) (pressure) (progressive) (spinal cord) (subacute), necrotizing, subacute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes (10)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Indexed Clinical Terms (1)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "G37.4 — Subacute necrotizing myelitis of central nervous system." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/g37.4-subacute-necrotizing-myelitis-of-central-nervous-system

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Subacute necrotizing myelitis of central nervous system

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to G37.4 in its code family, with their registry titles.

View all codes in the G37 family