ICD-10 Code G13.8 – Systemic atrophy primarily affecting central nervous system in other diseases classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G13.8 – Systemic atrophy primarily affecting central nervous system in other diseases classified elsewhere
What it is
This code identifies systemic atrophy affecting the central nervous system when it is due to another underlying disease classified elsewhere. Use it for degeneration that is part of a broader condition, not a stand-alone neurologic diagnosis.
Clinical signs
Clinical features vary; refer to documentation. You may see progressive neurologic decline, movement problems, gait disturbance, or autonomic features depending on the underlying disease and affected regions.
When to use this code
Use G13.8 when the provider documents systemic atrophy of the central nervous system and links it to another condition. This is appropriate when the neurologic degeneration is secondary, and the underlying disease is also coded. If the chart does not clearly identify the cause, check documentation.
Do not use for
Do not use this code for unspecified neurodegenerative disease or for atrophy not involving the central nervous system. Also avoid it when the record supports a different primary neurologic disorder. Check documentation.
Coding tip
Code the underlying disease first when documented, and verify that the provider explicitly connects the CNS atrophy to that condition.