Intraoperative magnetic resonance imaging in epilepsy surgery

The aim of this study was to investigate how intraoperative magnetic resona nce imaging (MRI) can help in epilepsy surgery to asses immediately whether a resection or disconnection procedure is tailored to the individual needs of a patient, thus ideally meeting the treatment plan and enhancing the ef ficiency of the procedure. The recently proposed concept of an individually tailored procedure with as limited tissue removal as possible would suppor t a more conservative resection than initially advocated by many centers; s uch limited removal would preserve as much brain as possible that is not ne cessarily epileptogenic or involved in propagation of seizures. For intraop erative imaging we used a Magnetom. Open 0.2-T scanner located in our "twin -OR" in 61 patients with pharmacoresistant epilepsy. A three-dimensional se quence was used, allowing free slice reformatting. In the nonlesional cases (n = 32) the extent of the tailored temporal resection (n = 28) or calloso tomy (n = 4) could be documented exactly. In the 29 lesional cases the comp lete resection was primarily proved in 23 patients. In three glioma patient s a lesion that extended into eloquent areas did not allow for complete rem oval. A second look (n = 3) could increase the rate of total resection in t he lesional cases from 79% to 90%. Intraoperative MRI allowed a reliable ev aluation of the extent of resection or disconnection in epilepsy surgery wi thin the operative procedure. It also provided the possibility of a second look in cases of incomplete resection, especially in the lesional cases. In creased knowledge of structure-function relationships as partially defined by intraoperative imaging may reduce the adverse neuropsychological sequela e of epilepsy surgery in the future. (C) 2000 Wiley-Liss, Inc.