Focal extratemporal epilepsy: clinical features, EEG patterns, and surgical approach

The objective of this review is a summary of the clinical and electrographic findings in those forms of epilepsy to which the term 'extratemporal' (ExT) can be applied. They form a group that differs in many ways from the better known temporal lobe epilepsies. Seizure foci are difficult to localize by clinical semiology alone but modern imaging now often allows a precise definition of the epileptogenic area. The most common causes of ExT epilepsy are tumors and cortical dysgenesis. The concept of 'dual pathology' implies the coexistence of two or more distinct lesions, typically mesial temporal sclerosis and cortical dysplasia. Electroencephalography (EEG) and electrocorticography (ECoG) are valuable tests in the definition of the epileptogenic area beyond the structural lesion, and surgical removal must be guided by the nature of the lesion and the extent of the epileptogenic zone.