ICD-10 Code G40.00 – Localization-related (focal) (partial) idiopathic epilepsy and epileptic syndromes with seizures of localized onset, not intractable (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G40.00 – Localization-related (focal) (partial) idiopathic epilepsy and epileptic syndromes with seizures of localized onset, not intractable
What it is
This code identifies idiopathic focal epilepsy with seizures that begin in one area of the brain and are not documented as intractable. Use it when the record supports a localized-onset epileptic syndrome without evidence of drug resistance.
Clinical signs
Clinical features vary; refer to documentation. Typical notes include recurrent focal seizures, possible aura, and onset from a specific cerebral region, with or without secondary generalization, when the provider identifies the syndrome as idiopathic.
When to use this code
Use G40.00 when the clinician documents localization-related or focal epilepsy with localized-onset seizures and does not state that it is intractable. It may also fit when the diagnosis is an idiopathic epileptic syndrome with focal seizures and no conflicting details. If the record is unclear, check documentation.
Do not use for
Do not use this code for intractable focal epilepsy, generalized epilepsy, or seizures without a confirmed epilepsy diagnosis. Avoid it when the chart only describes a single seizure event or when the seizure type and epilepsy classification are not documented.
Coding tip
Confirm both focal/localized onset and the nonintractable status in the provider note before assigning G40.00.