Is G04 a billable ICD-10-CM code?

No. G04 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does G04 sit in the tabular list?

Diseases of the nervous system (G00-G99), in the block Inflammatory diseases of the central nervous system (G00-G09).

What cannot be coded together with G04?

G04 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

G04

G04 — Encephalitis, myelitis and encephalomyelitis

Non-billable headerICD-10-CM

G04 is a non-billable header ICD-10-CM code for encephalitis, myelitis and encephalomyelitis. It cannot be billed on its own: choose one of the more specific child codes below.

Excludes1 — never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

encephalopathy NOS (G93.40)

Excludes2 — not included here, but may coexist

The excluded condition is not part of this code, but a patient can have both. You may code both.

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)

Includes

Conditions this code covers.

acute ascending myelitis
meningoencephalitis
meningomyelitis

Other codes that can never be billed with G04

These codes carry an Excludes1 note pointing at G04. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading G04 alone.

A80Acute poliomyelitis
G36Other acute disseminated demyelination
G00Bacterial meningitis, not elsewhere classified
G03Meningitis due to other and unspecified causes
G04.0Acute disseminated encephalitis and encephalomyelitis (ADEM)
G04.3Acute necrotizing hemorrhagic encephalopathy
G37.3Acute transverse myelitis in demyelinating disease of central nervous system

Risk adjustment

G04 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code to one of these instead G04

6 child codes. Green means billable.

Questions about G04

Is G04 a billable ICD-10-CM code?: No. G04 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does G04 sit in the tabular list?: Diseases of the nervous system (G00-G99), in the block Inflammatory diseases of the central nervous system (G00-G09).
What cannot be coded together with G04?: G04 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.