Abstract
Task-based functional magnetic resonance imaging (tfMRI) has developed as a common alternative in epilepsy surgery to the intracarotid amobarbital procedure (IAP), also known as the Wada procedure. Prior studies have implicated tfMRI as a comparable predictor of postsurgical cognitive outcomes. However, the predictive validity of tfMRI has not been established. This preregistered systematic review and meta-analysis (CRD42020183563) synthesizes the literature predicting postsurgical cognitive outcomes in temporal lobe epilepsy (TLE) using tfMRI. PubMed and PsychINFO literature databases were queried for English-language articles published between January 1, 2009 and December 31, 2020 associating tfMRI laterality indices or symmetry of task activation with outcomes in TLE. Their references were reviewed for additional relevant literature and unpublished data from our center was incorporated. Nineteen studies were included in the meta-analysis. tfMRI studies predicted postsurgical cognitive outcomes in left TLE (ρ̂ = -0.27, 95% CI = [-0.32, -0.23]) but not right TLE (ρ̂ = -0.02, 95% CI = [-0.08, 0.03]). Among studies of left TLE, language tfMRI studies were more robustly predictive of postsurgical cognitive outcomes (ρ̂ = -0.27, 95% CI = [-0.33, -0.20]) than memory tfMRI studies (ρ̂ = -0.27, 95% CI = [-0.43, -0.11]). Further moderation by cognitive outcome domain indicated language tfMRI predicted confrontation naming (ρ̂ = -0.32, 95% CI = [-0.41, -0.22]) and verbal memory (ρ̂ = -0.26, 95% CI = [-0.35, -0.17]) outcomes while memory tfMRI forecasted verbal memory outcomes only (ρ̂ = -0.37, 95% CI = [-0.57, -0.18]). Surgery type, birth sex, level of education, age of onset, disease duration, and hemispheric language dominance moderated study outcomes. Sensitivity analyses suggested the interval of postsurgical follow-up and reporting and methodological practices influenced study outcomes, as well. These findings intimate tfMRI is a modest predictor of outcomes in left TLE that should be considered in context of a larger surgical work-up.
DIC