Response: Can biomarkers of the epileptogenic zone be characterized in patients rendered seizure free alone?
The role ofpresurgical evaluation with intracranial elec-troencephalography (iEEG) is to localize the minimal amount ofbrain tissue which, ifresected, will achieve sei-zure freedom in the treated patient. From the definition ofthe epileptogenic zone (EZ)1being “the area ofcortex that is indispensable for the generation ofepileptic seizures,” it is the EZ that we want to localize. At the same time we will only know retrospectively in patients with seizure-free outcome that we were indeed able to identify the EZ.
This brings us to the localization dilemma. We either attempt to stick to the primary goal oflocalization ofthe EZ and use only good outcome patients or use something else as a localization target that is well defined in both good and poor outcomes. For poor outcome patients the latter remains less clear apart from the fact that at least part ofthe predicted target, localized by an algorithm, should be outside of the resection cavity.