Abstracts

Rationale: Epilepsy surgery is an effective treatment for seizure control but post-operative language deficits may occur. Pre-operative functional MRI (fMRI) language testing may be useful for predicting post-operative naming and fluency outcomes. We sought to determine whether regional fMRI lateralization predicts post-operative language outcomes. Methods: Twenty-nine patients (mean age 33.8 +/- 10.1 years) underwent a left or right frontal, temporal, or parietal lobectomy. Each patient completed preoperative 3T BOLD fMRI language mapping using a word definition decision task, as well as pre- and post-operative (mean 1.25 +/- .80 years) neuropsychological testing. We calculated regional fMRI activation laterality indices (LI) for inferior frontal gyrus (IFG), midfrontal gyrus (MFG), and Wernicke's Area (WA). Total resection volumes were calculated for each patient from post-operative MPRAGE MRI using manual resection tracing in MEDx. We examined pre- to post-operative change in naming ability (using the Boston Naming Test) and verbal fluency (using the Controlled Oral Word Association Test). Results: Eighty-three percent of patients had left language dominance. A 0.5 standard deviation (SD) decline in pre- to post-operative naming and fluency scores occurred in 15% and 9% of patients, respectively, while a 1 SD decline in naming and fluency occurred in 4% and 9% of patients. Additionally, 15% and 18% of patients exhibited an increase by 0.5 SD in pre- to post-operative naming and fluency scores, respectively. Also, 11% and 32% of patients showed a 1 SD increase in naming and fluency, respectively. Pre- to post-operative changes in naming scores negatively correlated with MFG laterality (p<0.05, r=-0.47), while changes in fluency scores negatively correlated with WA laterality (p<0.05, r=-0.43). Resection volume did not correlate with pre- to post-operative naming or fluency changes. Conclusions: Pre-operative fMRI language laterality is associated with post-operative language (naming and fluency) outcomes in patients undergoing epilepsy surgery. Increased left lateralization of language is related to a greater post-operative decline in naming and verbal fluency.