G05.4Myelitis in diseases classified elsewhere

G05.4 is the ICD-10-CM diagnosis code for myelitis in diseases classified elsewhere. It belongs to category G05 (encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere), block G00-G09 (inflammatory 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 G05 (encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere), G05.4 is specifically for myelitis in diseases classified elsewhere. Related codes cover encephalitis and encephalomyelitis in diseases classified elsewhere (G05.3).

Code first underlying disease, such as: congenital toxoplasmosis encephalitis, myelitis and encephalomyelitis (P37.1), cytomegaloviral encephalitis, myelitis and encephalomyelitis (B25.8), encephalitis, myelitis and encephalomyelitis (in) systemic lupus erythematosus (M32.19), eosinophilic meningoencephalitis (B83.2) and 5 more.

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) and DRG 099 (Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCC, relative weight 1.5256), in MDC 01 (Diseases and Disorders of the Nervous System), 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 is a manifestation code, so it describes the effect of an underlying disease and can't be the principal diagnosis. Code the underlying condition first.

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 323.42 (other myelitis due to other infections classified elsewhere).