G37.4Subacute necrotizing myelitis of central nervous system

G37.4 is the ICD-10-CM diagnosis code for subacute necrotizing myelitis of central nervous system. It belongs to category G37 (other demyelinating diseases of central nervous system), block G35-G37 (demyelinating diseases of the central nervous system) and chapter 6 (diseases of the nervous system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within G37 (other demyelinating diseases of central nervous system), G37.4 is specifically for subacute necrotizing myelitis of central nervous system. Related codes cover diffuse sclerosis of central nervous system (G37.0), central demyelination of corpus callosum (G37.1), central pontine myelinolysis (G37.2), acute transverse myelitis in demyelinating disease of central nervous system (G37.3), Concentric sclerosis [Balo] of central nervous system (G37.5), other specified demyelinating diseases of central nervous system (G37.8) and demyelinating disease of central nervous system, unspecified (G37.9).

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), DRG 099 (Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCC, relative weight 1.5256), DRG 974 (HIV with Major Related Condition with MCC, relative weight 3.0506) and 2 more, in MDC 01 (Diseases and Disorders of the Nervous System) and MDC 25 (Human Immunodeficiency Virus Infections), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 323.9 (unspecified causes of encephalitis, myelitis, and encephalomyelitis) and 341.8 (other demyelinating diseases of central nervous system).