ICD-10-CM 2027
ICD-10 code for cortical degeneration
From the official ICD-10-CM alphabetic index entry “Degeneration, degenerative › cortical (cerebellar) (parenchymatous)”. Page updated September 29, 2026.
About coding cortical degeneration
The ICD-10-CM code for cortical degeneration is G31.89 (Other specified degenerative diseases of nervous system). The official index lists 2 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on G31.89.
Within G31.8, choose G31.89 (Other specified degenerative diseases of nervous system) only when documentation doesn't support a more specific option: leukodystrophy, unspecified (G31.80), Alpers disease (G31.81), Leigh's disease (G31.82), neurocognitive disorder with Lewy bodies (G31.83), mild cognitive impairment of uncertain or unknown etiology (G31.84), Corticobasal degeneration (G31.85), Alexander disease (G31.86) and primary progressive apraxia of speech (G31.87).
Use an additional code, if applicable, for codes G31.0-G31.83, G31.85-G31.9, to identify: dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4), dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-), dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3), dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2), dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0) and 1 more.
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
More specific cortical degeneration codes (official index)
Common questions about cortical degeneration ICD-10 codes
What is the ICD-10 code for cortical degeneration?
- G31.89 — Other specified degenerative diseases of nervous system. More specific codes apply when the documentation supports them: G31.2, I67.2.
What is the ICD-10 code for alcoholic cortical degeneration?
- G31.2 — Degeneration of nervous system due to alcohol.
Is G31.89 billable?
- Yes. G31.89 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can G31.89 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict G31.89 as a principal diagnosis.
Is G31.89 a CC or MCC?
- No. G31.89 is neither a CC nor an MCC under MS-DRG v44.0.