Epilepsy surgery in MRI-negative epilepsies

Purpose of review: This study discusses the challenges of MRI-negative epilepsy surgery, and the strategies in using advanced MRI and functional imaging tests and their associated postsurgical outcome. Recent findings: Several methods for processing MRI postacquisition data have identified either previously undetectable or overlooked MRI abnormalities. The resection of these abnormalities is associated with excellent postsurgical seizure control. There have been major advances in functional imaging as well, one of which is the application of statistical parametric mapping analysis for comparing patient data against normative data. This approach has specifically improved the usefulness of both PET and single-photon emission computed tomography in MRI-negative epilepsy surgery evaluation. One other development of importance is that of PET-MRI coregistration, which has recently been shown to be superior to conventional PET. More recent publications on magnetoencephalography have added to the literature of its use in MRI-negative epilepsy surgery evaluation, which up to now remains somewhat limited. However, recent data now indicate that single magnetoencephalography cluster is associated with better chance of concordance with intracranial EEG localization, and with excellent postsurgical seizure control if completely resected. Summary: Advanced MRI and functional imaging and subsequent intracranial EEG confirmation of the seizure-onset zone are essential to make MRI-negative epilepsy surgery possible and worthwhile for the patient.