G31.9 — Degenerative disease of nervous system, unspecified
G31.9 is a billable, specific ICD-10-CM code for degenerative disease of nervous system, unspecified. It is valid for submission on a claim.
Other codes that can never be billed with G31.9
These codes carry an Excludes1 note pointing at G31.9. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading G31.9 alone.
Risk adjustment
G31.9 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.
Medicare coverage
G31.9 is named in 6 Medicare coverage policies — 6 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A53134Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions
- A54111Billing and Coding: Speech Language Pathology (SLP) Services: Communication Disorders
- A56619Billing and Coding: Nerve Conduction Studies and Electromyography
- A56937Billing and Coding: Psychiatry and Psychology Services
How G31.9 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to G31.9.
- Atrophy, atrophic›brain(cortex) (progressive)
- Degeneration, degenerative›brain(cortical) (progressive)
- Degeneration, degenerative›cerebellar NOS
- Degeneration, degenerative›nervous system
- Hemiatrophy›cerebellar
- Degeneration, degenerative›brain›childhood
Related codes at this level
Codes that share G31. If G31.9 is not quite right, the correct code is usually one of these.
Questions about G31.9
- Is G31.9 a billable ICD-10-CM code?
- Yes. G31.9 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does G31.9 sit in the tabular list?
- Diseases of the nervous system (G00-G99), in the block Other degenerative diseases of the nervous system (G30-G32).