ICD-10 Code G23.2 – Striatonigral degeneration (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G23.2 – Striatonigral degeneration
What it is
G23.2 identifies striatonigral degeneration, a rare progressive neurodegenerative disorder affecting the basal ganglia. It is part of the atypical parkinsonian syndromes and can cause motor impairment with poor response to standard Parkinson therapy.
Clinical signs
Typical findings include parkinsonism with rigidity, bradykinesia, postural instability, and gait disturbance. Clinical features vary; refer to documentation for supportive neurologic findings and whether the diagnosis is confirmed by specialist evaluation.
When to use this code
Use G23.2 when the provider documents striatonigral degeneration or clearly identifies this specific degenerative parkinsonian syndrome. It may also apply when the record supports this diagnosis as the cause of chronic movement disorder symptoms. Check documentation if the note only says Parkinson disease or unspecified parkinsonism.
Do not use for
Do not use this code for idiopathic Parkinson disease, drug-induced parkinsonism, or nonspecific tremor without a documented diagnosis. If the chart does not clearly support striatonigral degeneration, code the documented condition instead.
Coding tip
Assign G23.2 only when the provider names the disorder explicitly or links it clearly to the patient’s neurologic assessment.