G04 – Encephalitis, myelitis and encephalomyelitis

ICD-10-CM 2027 diagnosis code · Inflammatory diseases of the central nervous system

Non-billable header

ICD-10-CM code G04

Code: G04 (claims format: G04)
Description: Encephalitis, myelitis and encephalomyelitis
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 6. Diseases of the nervous system (G00-G99)
Block: G00-G09 Inflammatory diseases of the central nervous system

Billable codes under G04

G04 is a header code and cannot be used on claims. Choose the most specific code:

G04.0 – Acute disseminated encephalitis and encephalomyelitis (ADEM)Header (more codes below)
G04.1 – Tropical spastic paraplegiaBillable
G04.2 – Bacterial meningoencephalitis and meningomyelitis, not elsewhere classifiedBillable
G04.3 – Acute necrotizing hemorrhagic encephalopathyHeader (more codes below)
G04.8 – Other encephalitis, myelitis and encephalomyelitisHeader (more codes below)
G04.9 – Encephalitis, myelitis and encephalomyelitis, unspecifiedHeader (more codes below)

Notes for G04

Includes:

acute ascending myelitis
meningoencephalitis
meningomyelitis

Excludes1 (not coded here):

encephalopathy NOS (G93.40)

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)

Frequently asked questions

What is ICD-10 code G04?

G04 is the ICD-10-CM code for encephalitis, myelitis and encephalomyelitis, in the block G00-G09 (Inflammatory diseases of the central nervous system).

Is G04 a billable code?

No. G04 is a header code with more specific child codes; report one of the billable codes listed above.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.