Abstracts

Rationale: Surgical decision based on the cortical stimulation mapping (CSM) leads to postoperative language deficits in roughly 30%-60% of patients after left temporal lobe resection [1]. It has been shown that presurgical language mapping using high gamma electrocorticography (hgECoG) or functional MRI (fMRI) predicts postoperative language outcome [1,2]. The goal of this study was to predict postoperative language outcome using the results of presurgical language mapping based on hgECoG, fMRI, and transcranial magnetic stimulation (TMS).Methods: Four patients with epilepsy were included in this study (2 male; aged 17-27 years). All patients received pre- and postoperative neuropsychological evaluation of language using several measures covering various aspects of language (Table 1). A significant postoperative deficit in language was defined as a decline in any measure from pre- to postoperative assessment by one or more standard deviations. Presurgical language mapping was performed using hgECoG, TMS, and fMRI during object naming, sentence completion, and/or word generation tasks. The resected areas in all patients were identified. The number of hgECoG positive electrodes, regions with significant fMRI activities, and any TMS-induced speech disrupted site, namely the TMS site, within the resected area were identified for each patient.Results: Patients 1 and 2 had significant pre- to postoperative language deficit but Patients 3 and 4 did not show a decline. The resected area in Patient 1 was comprised of one hgECoG positive electrode, regions showing significant fMRI activity during an object naming task, and one TMS site. In Patient 2, hgECoG was not recorded. The resected area in this patient was comprised of none of TMS sites and regions showing significant fMRI activity during sentence completion and word generation tasks (Fig. 1). The resected area in Patient 3 did not include any positive hgECoG electrodes or regions showing significant fMRI activity during sentence completion or verb generation tasks. However, two TMS sites were resected in this patient. The resected area in Patient 4 did not include any positive hgECoG electrodes, TMS sites, or regions showing significant fMRI activity during sentence completion or word generation tasks. Overall, resection of any hgECoG positive electrodes, regions showing significant fMRI activity, and TMS sites predicted the postoperative language outcome in 3 out of 3, 4 out of 4, and 2 out of 4 patients, respectively.Conclusions: Our results show that the language mapping using hgECoG, fMRI, and TMS has a great potential for predicting postoperative language outcome. The results of this study have direct clinical applications and they may lead to improved neurosurgical procedures. Predicting postoperative language deficits has a significant impact on postsurgical outcome and is crucial for quality of life in patients undergoing epilepsy surgery. Acknowledgments This study was funded by the Children’s Foundation Research Institute, Memphis, TN. References 1. Neurology 2003; 60(11); 1788-92. 2. Clin Neurophysiol 2013; 124(5); 857-69.