ICD-10 Code G31.8 – Other specified degenerative diseases of nervous system (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G31.8 – Other specified degenerative diseases of nervous system
What it is
G31.8 identifies degenerative disorders of the nervous system that do not fit a more specific ICD-10-CM category. Use it when the record clearly describes a specified degenerative neurologic condition, but no better code is available.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings may include progressive neurologic decline, cognitive or motor impairment, or other evidence of nervous system degeneration.
When to use this code
Use G31.8 when the clinician documents a named degenerative nervous system disorder that is not indexed elsewhere in ICD-10-CM. It may also apply when the diagnosis is specific enough to show degeneration, but the chart does not support a more precise code. Check documentation carefully before assigning it.
Do not use for
Do not use this code for unspecified neurologic symptoms, dementia without a documented degenerative disorder, or conditions with a more specific ICD-10-CM code. If the record is unclear, check documentation.
Coding tip
Code the most specific documented degenerative neurologic diagnosis first, and use G31.8 only when no other ICD-10-CM option fits.