G23.9 Degenerative disease of basal ganglia, unspecified

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applies from G23 Other degenerative diseases of basal ganglia

Excludes2 (not included here)

• multi-system degeneration of the autonomic nervous system (G90.3)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 199 — Parkinson and Other Degenerative Disease of Basal Ganglia
• CMS-HCC V22: HCC 78 — Parkinson's and Huntington's Diseases
• RxHCC V08: HCC 161 — Parkinson Disease
• ESRD V24: HCC 78

MS-DRG index

Defines the logic of DRG(s) 056-057 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 333.0 Other degenerative diseases of the basal ganglia (approximate)

Code annotations containing back-references to G23.9

Back-references to G23

• Type 2 Excludes: F98.4 Stereotyped movement disorders ("movement disorders of organic origin (G20-G25)")
• Type 1 Excludes: R25 Abnormal involuntary movements ("specific movement disorders (G20-G26)")

Diagnosis Index entries for G23.9

• Degeneration, degenerative › basal nuclei or ganglia
• Disease, diseased › basal ganglia › degenerative

Nearby codes

• G23.0 Hallervorden-Spatz disease
• G23.1 Progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski]
• G23.2 Striatonigral degeneration
• G23.3 Hypomyelination with atrophy of the basal ganglia and cerebellum
• G23.8 Other specified degenerative diseases of basal ganglia
• G23.9 Degenerative disease of basal ganglia, unspecified (this code)