2026 ICD-10-CM Diagnosis Code G23.9Degenerative disease of basal ganglia, unspecified

ICD-10-CM Codes›G00–G99›G20-G26›G23

ICD-10-CM G23.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G23.9 is a billable ICD-10-CM diagnosis code for degenerative disease of basal ganglia, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as pallidal degeneration. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (often hereditary or degenerative).

Code Identity

ICD-10-CM Code
G23.9
Billable Status
Yes — Valid for Submission
Code Describes
Degenerative disease of basal ganglia, unspecified
Short Description
Degenerative disease of basal ganglia, unspecified
Same as the full description in the CMS dataset.
Parent Code
G23
Other degenerative diseases of basal ganglia

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG20-G26Extrapyramidal and movement disorders
CategoryG23Other degenerative diseases of basal ganglia
This CodeG23.9Degenerative disease of basal ganglia, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Pallidal degeneration
  • Pallidonigroluysian degeneration
  • Pallidopontonigral degeneration

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

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

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS006
Other nervous system disorders (often hereditary or degenerative)
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Degenerative Nerve Diseases

Degenerative nerve diseases affect many of your body's activities, such as balance, movement, talking, breathing, and heart function. Many of these diseases are genetic. Sometimes the cause is a medical condition such as alcoholism, a tumor, or a stroke. Other causes may include toxins, chemicals, and viruses.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G23.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
333.0 Degen basal ganglia NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G23.9Overview

Is G23.9 (Other degenerative diseases of basal ganglia) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report degenerative disease of basal ganglia, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of G23.9?

Under the General Equivalence Mappings, degenerative disease of basal ganglia, unspecified converts to ICD-9-CM 333.0 (degen basal ganglia NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.