seizure focus
The specific brain region where seizure activity originates, identified through ictal EEG patterns and clinical correlation.
Full Definition
A seizure focus represents the anatomical site of seizure initiation, typically characterized by specific electrographic patterns during ictal events. The focus may show interictal epileptiform discharges between seizures and demonstrates characteristic frequency evolution and propagation patterns during seizure onset. Accurate focus localization is crucial for surgical planning in medically refractory epilepsy. Multiple diagnostic modalities including scalp EEG, invasive monitoring, neuroimaging, and clinical semiology contribute to focus identification. The focus may be unifocal, multifocal, or part of an epileptogenic network.
Usage
Usage note: Distinguish from broader terms like 'epileptogenic zone' which may include surrounding tissue.
In Context
- "The seizure focus was localized to the left mesial temporal region based on ictal EEG findings." — Presurgical evaluation report
- "Invasive monitoring was recommended to better define the seizure focus before considering surgical resection." — Epilepsy consultation note