G04.0 — Acute disseminated encephalitis and encephalomyelitis (ADEM)
G04.0 is a non-billable header ICD-10-CM code for acute disseminated encephalitis and encephalomyelitis (adem). 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.
Excludes1 inherited from the categories above G04.0
These are not written on G04.0, but they bind it: a note on a category applies to every code beneath it. Billing G04.0 with anything listed here is a denial.
Excludes2 inherited from the categories above G04.0
Also inherited, and the opposite of Excludes1: these conditions are not part of G04.0, but a patient can have both, so you may code both.
Other codes that can never be billed with G04.0
These codes carry an Excludes1 note pointing at G04.0. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading G04.0 alone.
Risk adjustment
G04.0 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 history
G04.0 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.
Code to one of these instead G04.0
3 child codes. Green means billable.
Related codes at this level
Codes that share G04. If G04.0 is not quite right, the correct code is usually one of these.
Questions about G04.0
- Is G04.0 a billable ICD-10-CM code?
- No. G04.0 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
- Where does G04.0 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 G04.0?
- G04.0 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above G04.0 (G04) and apply to it just the same.