ICD-10 Code G31 – Other degenerative diseases of nervous system, not elsewhere classified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G31 – Other degenerative diseases of nervous system, not elsewhere classified
What it is
G31 is a broad category for degenerative nervous system disorders that do not fit a more specific ICD-10 code. Use it when the record describes a progressive neurologic degeneration, but the exact condition is not named.
Clinical signs
Clinical features vary; refer to documentation. Records may describe progressive cognitive, motor, or functional decline, with neurologic deterioration that is not better classified elsewhere.
When to use this code
Use G31 when the provider documents an unspecified or other degenerative disease of the nervous system and no more specific diagnosis is available. It may also fit when the chart confirms a degenerative neurologic process but does not identify a distinct subtype. Check documentation before assigning it.
Do not use for
Do not use G31 when the record supports a more specific degenerative neurologic diagnosis, such as a named dementia or other coded disorder. If the documentation is vague, check documentation rather than guessing.
Coding tip
Always code the most specific documented neurologic degeneration first, and use G31 only when no better-defined option is supported.