ICD-10-CM G04: Encephalitis, myelitis and encephalomyelitis

ICD-10-CM Diagnosis Code (2025)

Official Description for G04

Encephalitis, myelitis and encephalomyelitis

Coding Notes & Guidelines for G04

Includes Notes
  • acute ascending myelitis
  • meningoencephalitis
  • meningomyelitis
Excludes1: Not Coded Here

encephalopathy NOS (G93.40)

Excludes1: Not Coded Here
  • acute necrotizing hemorrhagic encephalopathy (G04.3-)
  • other noninfectious acute disseminated encephalomyelitis (noninfectious ADEM) (G04.81)
Excludes1: Not Coded Here
  • post chickenpox encephalitis (B01.1)
  • post measles encephalitis (B05.0)
  • post measles myelitis (B05.1)
Excludes1: Not Coded Here

acute disseminated encephalitis and encephalomyelitis (G04.0-)

Excludes1: Not Coded Here

transverse myelitis (G37.3)

Excludes2: Not Included Here
  • 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)
Use Additional Code

code to identify the vaccine (T50.A-, T50.B-, T50.Z-)

Use Additional Code

code to identify the vaccine (T50.A-, T50.B-, T50.Z-)

Inclusion Terms
  • Encephalitis, post immunization
  • Encephalomyelitis, post immunization
Inclusion Terms

Noninfectious acute disseminated encephalomyelitis (noninfectious ADEM)

Inclusion Terms

Ventriculitis (cerebral) NOS

Code Also

underlying etiology, if applicable

Code Also

any associated seizure (G40.-, R56.9)

Child Codes (More Specific Codes for G04):

G04.0 - Acute disseminated encephalitis and encephalomyelitis (ADEM) G04.00 - Acute disseminated encephalitis and encephalomyelitis, unspecified G04.01 - Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM) G04.02 - Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis G04.1 - Tropical spastic paraplegia G04.2 - Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified G04.3 - Acute necrotizing hemorrhagic encephalopathy G04.30 - Acute necrotizing hemorrhagic encephalopathy, unspecified G04.31 - Postinfectious acute necrotizing hemorrhagic encephalopathy G04.32 - Postimmunization acute necrotizing hemorrhagic encephalopathy G04.39 - Other acute necrotizing hemorrhagic encephalopathy G04.8 - Other encephalitis, myelitis and encephalomyelitis G04.81 - Other encephalitis and encephalomyelitis G04.82 - Acute flaccid myelitis G04.89 - Other myelitis G04.9 - Encephalitis, myelitis and encephalomyelitis, unspecified G04.90 - Encephalitis and encephalomyelitis, unspecified G04.91 - Myelitis, unspecified

About ICD-10-CM Code G04 (Encephalitis)

ICD-10-CM code G04 is a billable or specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes. The 2025 edition of ICD-10-CM G04 became effective on October 1, 2024.

This page provides detailed information about G04 - Encephalitis, myelitis and encephalomyelitis. It includes common terminology, coding guidelines such as "Includes," "Excludes1," and "Excludes2" notes, and information on required 7th characters. Utilizing this information correctly is essential for accurate medical coding and claims submission for conditions like Encephalitis related to myelitis and encephalomyelitis.