ICD-10-CM 2027
ICD-10 code for nervous system degeneration
From the official ICD-10-CM alphabetic index entry “Degeneration, degenerative › nervous system”. Page updated September 29, 2026.
About coding nervous system degeneration
The ICD-10-CM code for nervous system degeneration is G31.9 (Degenerative disease of nervous system, unspecified). The official index lists 5 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on G31.9.
Within G31, choose G31.9 (Degenerative disease of nervous system, unspecified) only when documentation doesn't support a more specific option: frontotemporal dementia (G31.0), senile degeneration of brain, not elsewhere classified (G31.1), degeneration of nervous system due to alcohol (G31.2) and other specified degenerative diseases of nervous system (G31.8).
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 nervous system degeneration codes (official index)
- alcoholic G31.2 — Degeneration of nervous system due to alcohol
- amyloid E85.4 — Organ-limited amyloidosis
- autonomic G90.9 — Disorder of the autonomic nervous system, unspecified
- fatty G31.89 — Other specified degenerative diseases of nervous system
- specified NEC G31.89 — Other specified degenerative diseases of nervous system
Common questions about nervous system degeneration ICD-10 codes
What is the ICD-10 code for nervous system degeneration?
- G31.9 — Degenerative disease of nervous system, unspecified. More specific codes apply when the documentation supports them: G31.2, E85.4, G90.9, G31.89 and others below.
What is the ICD-10 code for alcoholic nervous system degeneration?
- G31.2 — Degeneration of nervous system due to alcohol.
What is the ICD-10 code for amyloid nervous system degeneration?
- E85.4 — Organ-limited amyloidosis.
What is the ICD-10 code for autonomic nervous system degeneration?
- G90.9 — Disorder of the autonomic nervous system, unspecified.
What is the ICD-10 code for fatty nervous system degeneration?
- G31.89 — Other specified degenerative diseases of nervous system.
Is G31.9 billable?
- Yes. G31.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can G31.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict G31.9 as a principal diagnosis.
Is G31.9 a CC or MCC?
- No. G31.9 is neither a CC nor an MCC under MS-DRG v44.0.