ICD-10 Code G40.01 – Localization-related (focal) (partial) idiopathic epilepsy and epileptic syndromes with seizures of localized onset, intractable (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G40.01 – Localization-related (focal) (partial) idiopathic epilepsy and epileptic syndromes with seizures of localized onset, intractable
What it is
This code identifies idiopathic focal epilepsy with seizures that start in one area of the brain and are difficult to control. Use it when the diagnosis specifically states intractable or poorly controlled localized-onset seizures.
Clinical signs
Clinical features vary; refer to documentation. Typical focal seizures may include localized motor, sensory, autonomic, or awareness changes, and the record should support an idiopathic epilepsy diagnosis with intractability.
When to use this code
Use G40.01 when the provider documents localization-related or focal idiopathic epilepsy with seizures of localized onset and states that the condition is intractable. It also fits when the chart clearly describes persistent seizures despite treatment and no secondary cause is identified. Check documentation if seizure type or control status is unclear.
Do not use for
Do not use this code for generalized epilepsy, seizures without an epilepsy diagnosis, or focal seizures caused by a known structural, metabolic, or other secondary condition. Check documentation if the record does not specify idiopathic or intractable disease.
Coding tip
Confirm both focal onset and intractability in the provider note before assigning G40.01.