ICD-10 Code G40.31 – Generalized idiopathic epilepsy and epileptic syndromes, intractable (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G40.31 – Generalized idiopathic epilepsy and epileptic syndromes, intractable
What it is
G40.31 identifies generalized idiopathic epilepsy and epileptic syndromes that are difficult to control with treatment. Use it when the provider documents a generalized epilepsy syndrome with persistent seizures despite appropriate therapy.
Clinical signs
Clinical features vary; refer to documentation. Common generalized seizure patterns may include absence, myoclonic, or generalized tonic-clonic events, with onset not explained by a structural brain lesion or another known cause.
When to use this code
Use this code when the record clearly states generalized idiopathic epilepsy or a related generalized epileptic syndrome and also describes it as intractable, refractory, or poorly controlled. The diagnosis should be supported by ongoing seizures despite treatment. Check documentation if the seizure type or epilepsy category is unclear.
Do not use for
Do not use this code for seizures due to acute illness, trauma, or a known secondary cause. Do not use it when the epilepsy is controlled or when the provider documents a different epilepsy classification.
Coding tip
Confirm both the generalized idiopathic epilepsy diagnosis and the intractable status in the provider note before assigning G40.31.