Encephalitis, myelitis and encephalomyelitis
In Inflammatory diseases of the central nervous system (G00-G09), chapter 6: Diseases of the Nervous System
14 billable codes under G04: 13 are an MCC, 1 is a CC; 4 map to HCC 182 (Spinal Cord Disorders/Injuries).A CC or MCC (major CC) is a secondary diagnosis that raises the MS-DRG payment. An HCC counts toward a Medicare Advantage patient's risk score.
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Instructional notes
Includes: conditions that are coded here
- acute ascending myelitis
- meningoencephalitis
- meningomyelitis
Excludes1: not coded here, use a different code
- encephalopathy NOS (G93.40)
Official coding guidelines
From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.
Covers default dominant or nondominant side for hemiplegia and monoplegia, and use and sequencing of G89 pain codes, including postoperative, chronic, and neoplasm-related pain.
- Dominant/nondominant side (page 45)
- Pain - Category G89 (page 45)
All codes under G04
G04 can't be used on a claim. Pick a billable code below; grey headings group them.
- G04.0Acute disseminated encephalitis and encephalomyelitis (ADEM)
- G04.00Acute disseminated encephalitis and encephalomyelitis, unspecified
- G04.01Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)
- G04.02Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis
- G04.1Tropical spastic paraplegia
- G04.2Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified
- G04.3Acute necrotizing hemorrhagic encephalopathy
- G04.30Acute necrotizing hemorrhagic encephalopathy, unspecified
- G04.31Postinfectious acute necrotizing hemorrhagic encephalopathy
- G04.32Postimmunization acute necrotizing hemorrhagic encephalopathy
- G04.39Other acute necrotizing hemorrhagic encephalopathy
- G04.8Other encephalitis, myelitis and encephalomyelitis
- G04.81Other encephalitis and encephalomyelitis
- G04.82Acute flaccid myelitis
- G04.89Other myelitis
- G04.9Encephalitis, myelitis and encephalomyelitis, unspecified
- G04.90Encephalitis and encephalomyelitis, unspecified
- G04.91Myelitis, unspecified
G04 MS-DRGs
As the principal diagnosis, the billable codes under G04 group to these 15 MS-DRGs (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
- DRG 023 Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator (13 of 14 codes)
- DRG 024 Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC (13 of 14 codes)
- DRG 097 Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC (12 of 14 codes)
- DRG 098 Non-Bacterial Infection of Nervous System Except Viral Meningitis with CC (12 of 14 codes)
- DRG 099 Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCC (12 of 14 codes)
- DRG 974 HIV with Major Related Condition with MCC (4 of 14 codes)
- DRG 975 HIV with Major Related Condition with CC (4 of 14 codes)
- DRG 976 HIV with Major Related Condition without CC/MCC (4 of 14 codes)
- DRG 052 Spinal Disorders and Injuries with CC/MCC (1 of 14 codes)
- DRG 053 Spinal Disorders and Injuries without CC/MCC (1 of 14 codes)
- DRG 094 Bacterial and Tuberculous Infections of Nervous System with MCC (1 of 14 codes)
- DRG 095 Bacterial and Tuberculous Infections of Nervous System with CC (1 of 14 codes)
- DRG 096 Bacterial and Tuberculous Infections of Nervous System without CC/MCC (1 of 14 codes)
- DRG 791 Prematurity with Major Problems (1 of 14 codes)
- DRG 793 Full Term Neonate with Major Problems (1 of 14 codes)
Other codes that refer to G04
Notes on these codes point to G04.
About the condition
Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.
Encephalitis
Encephalitis is inflammation (swelling) of the brain. It can happen when an infection or medical condition that affects the brain activates your immune system. The inflammation can cause a wide range of symptoms. In extreme cases, it can lead to brain damage, stroke, or even death.
Read more about encephalitis on MedlinePlusSpinal Cord Diseases
Your spinal cord is a bundle of nerves that runs down the middle of your back. It carries signals back and forth between your body and your brain. It is protected by your vertebrae, which are the bone disks that make up your spine. If you have an accident that damages the vertebrae or other parts of the spine, this can also injure the spinal cord. Other spinal cord problems include:
Read more about spinal cord diseases on MedlinePlusCode history
Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.