Higher resolution MRI and image modeling for predicting surgical outcome in partial epilepsy.

Epilepsy affects 1 to 2% of the population and partial epilepsies account for approximately 40% of all epilepsies in adults. Of these, up to 30% may be resistant to medical treatment with antiepileptic drugs (AEDs). In the past, physicians, including many neurologists, have considered epilepsy surgery the treatment of last resort for patients with partial epilepsies. The average duration of surgically treatable epilepsy among young and middle-aged adults referred for epilepsy surgery at major epilepsy centers was once almost 20 years. Although further trials are needed, surgery ought to be considered in patients with partial epilepsy who fail two AEDs.1 Defining the cause of the epilepsy and localization of the seizure generator are essential for surgical planning and prognosis. Knake et al. showed that the use of phased array surface coil at 3 Tesla MRI analyzed by experienced epileptologists detected unrecognized lesions in 65% of previously MRI-negative patients and provided additional information in almost half of patients with temporal lobe epilepsy (TLE) and frontal lobe epilepsy. This important study shows that proper identification of abnormal tissue, which may otherwise be unrecognized, is crucial for identifying a potential epileptic focus, and thereby increases the likelihood of a better surgical outcome,2,3 and, as a corollary, for identifying whether such abnormalities are widespread, and thus less amenable to surgical treatment. Lin et al. showed that new computational methods, using threedimensional surface meshes to model hippocampal anatomy, allowed the identification of regionspecific hippocampal volume differences in patients with TLE who became seizure free after surgery. These regions of atrophy are not easily detected by routine MRI and may indicate areas of increased epileptogenesis. Additional questions arise. Should general neurologists be arranging for their patients to receive these sophisticated acquisition and post-processing MRI techniques? While there is still no standard approach, all patients with refractory partial epilepsy, particularly those with normal routine MRI, should be referred to a dedicated MRI center and images should be reviewed by physicians experienced in the evaluation of patients with epilepsy.2,3 Might these tests point the way to more restricted surgical approaches, a lesionectomy? Would such procedures be better tolerated and equally efficacious? More studies are needed to address these questions, but as our imaging becomes more refined, so will our ability to ask and answer more complex and subtle questions about the management of medically resistant partial epilepsy. This may be the greatest argument in favor of promoting newer imaging techniques.