2027 ICD-10-CM Diagnosis Code G04Encephalitis, myelitis and encephalomyelitis

ICD-10-CM Codes›G00–G99›G00-G09›G04

ICD-10-CM G04
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G04 is a non-billable ICD-10-CM category code for encephalitis, myelitis and encephalomyelitis, so it cannot be submitted on claims. Use a more specific code from this category instead, such as G04.00, G04.01, G04.02, and G04.1.

Code Identity

ICD-10-CM Code
G04
Billable Status
No — Non-Billable Category
Code Describes
Encephalitis, myelitis and encephalomyelitis
Short Description
Encephalitis, myelitis and encephalomyelitis
Same as the full description in the CMS dataset.
Chapter
G00-G09
Inflammatory diseases of the central nervous system

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG00-G09Inflammatory diseases of the central nervous system
CategoryG04Encephalitis, myelitis and encephalomyelitis
This CodeG04Encephalitis, myelitis and encephalomyelitis

Specific Coding for Encephalitis, myelitis and encephalomyelitisOverview

Non-specific codes like G04 require more characters. Use one of these billable codes instead:

  • G04.0 for Acute disseminated encephalitis and encephalomyelitis (ADEM)

  • Use G04.00 for Acute disseminated encephalitis and encephalomyelitis, unspecified

  • Use G04.01 for Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)

  • Use G04.02 for Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis

  • Use G04.1 for Tropical spastic paraplegia

  • Use G04.2 for Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified

  • G04.3 for Acute necrotizing hemorrhagic encephalopathy

  • Use G04.30 for Acute necrotizing hemorrhagic encephalopathy, unspecified

  • Use G04.31 for Postinfectious acute necrotizing hemorrhagic encephalopathy

  • Use G04.32 for Postimmunization acute necrotizing hemorrhagic encephalopathy

  • Use G04.39 for Other acute necrotizing hemorrhagic encephalopathy

  • G04.8 for Other encephalitis, myelitis and encephalomyelitis

  • Use G04.81 for Other encephalitis and encephalomyelitis

  • Use G04.82 for Acute flaccid myelitis

  • Use G04.89 for Other myelitis

  • G04.9 for Encephalitis, myelitis and encephalomyelitis, unspecified

  • Use G04.90 for Encephalitis and encephalomyelitis, unspecified

  • Use G04.91 for Myelitis, unspecified

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G04: its own notes plus those printed at Chapter 6. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

  • acute ascending myelitis
  • meningoencephalitis
  • meningomyelitis

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

On G04 itself
  • acute transverse myelitis (G37.3)
  • alcoholic encephalopathy (G31.2)
  • multiple sclerosis (G35-)
  • myalgic encephalomyelitis (G93.32)
  • subacute necrotizing myelitis (G37.4)
  • toxic encephalitis (G92.8)
  • toxic encephalopathy (G92.8)
From Chapter 6 (G00-G99) Diseases of the nervous system applies to 700 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name G04, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming G04: they are not reported together with it, unless the two conditions are unrelated.

  • G03 Meningitis due to other and unspecified causes
    meningoencephalitis (G04.-)
  • G03 Meningitis due to other and unspecified causes
    meningomyelitis (G04.-)

Excludes2 1

These codes carry an Excludes2 note naming G04: its condition is not part of those codes, and both may be reported when the patient has both.

  • G95 Other and unspecified diseases of spinal cord
    myelitis (G04.-)

Notes 1

These notes mention G04.

  • G09 Sequelae of inflammatory diseases of central nervous system
    Category G09 is to be used to indicate conditions whose primary classification is to G00-G08 as the cause of sequelae, themselves classifiable elsewhere. The 'sequelae' include conditions specified as residuals. names G00-G08, which includes this code

Patient EducationClinical

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.

The full article covers:

  • What is encephalitis?
  • What causes encephalitis?
  • Who is more likely to get encephalitis?
  • What are the symptoms of encephalitis?
  • How is encephalitis diagnosed?
  • What are the treatments for encephalitis?
  • Can encephalitis be prevented?

Read the full article at MedlinePlus

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

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About G04Overview

What is the ICD-10 code for encephalitis, myelitis and encephalomyelitis?

G04 is the ICD-10-CM category for encephalitis, myelitis and encephalomyelitis, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

Is G04 (Encephalitis, myelitis and encephalomyelitis) a billable code?

No. This is a category header that groups the codes for encephalitis, myelitis and encephalomyelitis, and headers cannot be submitted on claims. Claims for encephalitis, myelitis and encephalomyelitis need a more specific code from this category, such as G04.00, G04.01, and G04.02.

Can G04 be reported with G93.40?

Not as a rule. The Excludes1 note on G04 lists "encephalopathy NOS (G93.40)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).