Carter D. Wray, Sharon S. McDaniel, Russell P. Saneto, Edward J. Novotny Jr. and Jeffrey G. Ojemann
Intraoperative electrocorticography (ECoG) is commonly used to guide the extent of resection, especially in lesion-associated intractable epilepsy. Interictal epileptiform discharges on postresective ECoG (post-ECoG) have been predictive of seizure recurrence in some studies, particularly in adults undergoing medial temporal lobectomy, frontal lesionectomy, or low-grade glioma resection. The predictive value of postresective discharges in pediatric epilepsy surgery has not been extensively studied.
The authors retrospectively examined the charts of all 52 pediatric patients who had undergone surgery with post-ECoG and had more than 1 year of follow-up between October 1, 2003, and October 1, 2009.
Of the 52 pediatric patients, 37 patients showed residual discharges at the end of their resection and 73% of these patients were seizure free, whereas 15 patients had no residual discharges and 60% of them were seizure-free, which was not significantly different (p = 0.36, chi-square).
Electrocorticography-guided surgery was associated with excellent postsurgical outcome. Although this sample size was too small to detect a subtle difference, absence of epileptiform discharges on post-ECoG does not appear to predict seizure freedom in all pediatric patients referred for epilepsy surgery. Future studies with larger study samples would be necessary to confirm this finding and determine whether post-ECoG may be useful in some subsets of pediatric epilepsy surgery candidates.
Sandra L. Poliachik, Andrew V. Poliakov, Laura A. Jansen, Sharon S. McDaniel, Carter D. Wray, John Kuratani, Russell P. Saneto, Jeffrey G. Ojemann and Edward J. Novotny Jr
Imaging-guided surgery (IGS) systems are widely used in neurosurgical practice. During epilepsy surgery, the authors routinely use IGS landmarks to localize intracranial electrodes and/or specific brain regions. The authors have developed a technique to coregister these landmarks with pre- and postoperative scans and the Montreal Neurological Institute (MNI) standard space brain MRI to allow 1) localization and identification of tissue anatomy; and 2) identification of Brodmann areas (BAs) of the tissue resected during epilepsy surgery. Tracking tissue in this fashion allows for better correlation of patient outcome to clinical factors, functional neuroimaging findings, and pathological characteristics and molecular studies of resected tissue.
Tissue samples were collected in 21 patients. Coordinates from intraoperative tissue localization were downloaded from the IGS system and transformed into patient space, as defined by preoperative high-resolution T1-weighted MRI volume. Tissue landmarks in patient space were then transformed into MNI standard space for identification of the BAs of the tissue samples.
Anatomical locations of resected tissue were identified from the intraoperative resection landmarks. The BAs were identified for 17 of the 21 patients. The remaining patients had abnormal brain anatomy that could not be meaningfully coregistered with the MNI standard brain without causing extensive distortion.
This coregistration and landmark tracking technique allows localization of tissue that is resected from patients with epilepsy and identification of the BAs for each resected region. The ability to perform tissue localization allows investigators to relate preoperative, intraoperative, and postoperative functional and anatomical brain imaging to better understand patient outcomes, improve patient safety, and aid in research.