G31.85 — Corticobasal degeneration
G31.85 is a billable, specific ICD-10-CM code for corticobasal degeneration. It is valid for submission on a claim.
Risk adjustment
G31.85 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
G31.85 is named in 20 Medicare coverage policies — 19 listing it as supporting medical necessity, and 1 listing it as NOT covered. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A52434Health and Behavior Assessment/Intervention – Medical Policy Articlenot covered
- A53052Billing and Coding: Home Health Speech-Language Pathology
- A53057Billing and Coding: Home Health Occupational Therapy
- A53058Billing and Coding: Home Health Physical Therapy
How G31.85 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 G31.85.
- Degeneration, degenerative›corticobasal
Related codes at this level
Codes that share G31.8. If G31.85 is not quite right, the correct code is usually one of these.
- G31.80Leukodystrophy, unspecified
- G31.81Alpers disease
- G31.82Leigh's disease
- G31.83Neurocognitive disorder with Lewy bodies
- G31.84Mild cognitive impairment of uncertain or unknown etiology
- G31.86Alexander disease
- G31.87Primary progressive apraxia of speech
- G31.89Other specified degenerative diseases of nervous system
Questions about G31.85
- Is G31.85 a billable ICD-10-CM code?
- Yes. G31.85 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does G31.85 sit in the tabular list?
- Diseases of the nervous system (G00-G99), in the block Other degenerative diseases of the nervous system (G30-G32).