Modern concepts in the evaluation for epilepsy surgery

The benefits of surgical treatment for epilepsy have been clear for many years, and evidence-based guidelines have reinforced the importance of surgical treatment for some forms of epilepsy. Overall, the benefits of surgery relate to both the high prevalence of medication-resistant epilepsy and also the increasing effectiveness of surgical treatment. However, much of the increasing effectiveness has emerged from advances in the surgical evaluation. The rising seizure-free rates after surgery for some forms of epilepsy relate to the greater specificity of the evaluation for the epileptogenic zone. Furthermore, the increasing numbers of candidates for surgical treatment relates to the greater sensitivity of the evaluation across diverse pathologic causes for epilepsy. Historically, the epilepsy surgery evaluation has progressed from the use of seizure manifestation, to intracranial EEG, and then to extracranial EEG with functional and then structural imaging. The inclusion of complementary techniques and the advances in resolution and interpretation have improved the evaluation substantially in the modern era, and considerable progress continues to result from new understanding on how to integrate the collection of diagnostic information. All of these advances have been predicated on the concept that focal seizures are due to a focal abnormality. Looking forward, we now are at the cusp of a shift toward conceptualizing epilepsy as network abnormality. With incorporation of this more sophisticated understanding into the evaluation of epilepsy, surgical success will hopefully continue to grow.