Abstracts

Rationale: Epilepsy surgery is an effective treatment for drug-resistant focal epilepsy. Neuroimaging studies are considered essential in the diagnostic evaluation of individuals with medically refractory focal seizures being considered for surgical treatment. The rationale for this study is to review the evidence for the use of neuroimaging studies in the selection of patients with pharmacoresistant temporal lobe epilepsy for focal cortical resection, and to discuss the prognostic importance of selected techniques. Methods: Randomized clinical trials, meta-analyses, and clinical retrospective studies (20 patients or more with at least 1 year follow-up) were identified using Medical Subject Headings and indexed terms in Embase (1988-Nov. 29, 2014); Medline (1946-Dec. 2, 2014); Cochrane Central Register of Controlled Trials (1991-Oct. 31, 2014); and Cochrane Database of Systemic Reviews (2005-Oct. 31, 2014). Twenty-seven articles describing 3,163 patients were included. Neuroimaging techniques analyzed include magnetic resonance imaging (MRI), positron emission tomography (PET), and single photon emission computed and tomography (SPECT). Subpopulations and prognostic factors were identified. Results: Of the 27 studies evaluated (3,163 patients), 7 showed the outcome was more favorable in patients with MRI-identified hippocampal atrophy indicating mesial temporal sclerosis (MTS). Five additional studies indicated that the outcome was less favorable in patients with unremarkale MRI studies. There are conflicting studies regarding the prognostic importance of PET-identified focal hypometabolism, however, 2 investigations indicated that the presence of a PET positive imaging study in individuals with negative MRI showed a similar operative outcome as patients with MTS. The studies assessing SPECT and temporal lobe epilepsy did not reveal a correlation with outcome. Conclusions: There is strong evidence that preoperative MRI-identified hippocampal pathology consistent with MTS concordant with the temporal lobe of seizure origin is a significant predictor of a favorable outcome. PET studies may be valuable in individuals with negative MRI studies. The current evidence did not support the prognostic importance of SPECT in patients undergoing temporal lobe surgery. Funding: None.