LAUSR

Objective: To assess the utility of EEG-fMRI for epilepsy surgery, we evaluated surgical outcome in relation to the resection of the most signi fi cant EEG-fMRI response. Methods: Patients with post-operative neuroimaging and follow-up of at least 1 year were included. In EEG-fMRI responses, we de fi ned as “ primary ” the cluster with the highest absolute t-value located in the cortex, and evaluated three levels of con fi dence for the results. The threshold for low con fi dence was t ≥ 3.1 ( P < .005); the one for medium con fi dence corresponded to correction for multiple comparisons with a false discovery rate of .05; and a result reached high con fi dence when the primary cluster was much more signi fi cant than the next highest cluster. Concordance with the resection was determined by comparison to post-operative neuroimaging. Results: We evaluated 106 epilepsy surgeries in 84 patients. An increasing association between concordance and surgical outcome with higher levels of con fi dence was demonstrated. If the peak response was not resected, the surgical outcome was likely to be poor: for the high con fi dence level, no patient had a good outcome; for the medium and low levels, only 18% and 28% had a good outcome. The positive predictive value remained low for all con fi dence levels, indicating that removing the maximum cluster did not ensure seizure freedom. Conclusion: Resection of the primary EEG-fMRI cluster, especially in high con fi dence cases, is necessary to obtain a good outcome, but not suf fi cient. Classi fi cation of Evidence: This study provided Class II evidence that failure to resect the primary EEG-fMRI cluster is associated with poorer epilepsy surgery outcomes.