ICD-10 Code A81.83 – Fatal familial insomnia (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A81.83 – Fatal familial insomnia
What it is
A81.83 identifies fatal familial insomnia, a rare inherited prion disease that causes progressive sleep loss and neurologic decline. Use it when documentation names this specific disorder.
Clinical signs
Typical findings include worsening insomnia, autonomic dysfunction, cognitive decline, and movement or coordination problems. Clinical features vary; refer to documentation.
When to use this code
Use A81.83 when the record clearly states fatal familial insomnia or familial prion disease with this diagnosis. Code it from physician documentation, genetic evaluation, or specialist assessment when the condition is confirmed or strongly supported.
Do not infer this code from nonspecific sleep disturbance, dementia, or unexplained neurologic symptoms alone. If the chart only says “insomnia” or “prion disease,” check documentation for the exact diagnosis.
Do not use for
Do not use A81.83 for routine insomnia, psychiatric sleep disorders, or other prion diseases without fatal familial insomnia documented. Check documentation if the diagnosis is uncertain.
Coding tip
Look for the full named diagnosis in the assessment or problem list before assigning A81.83.