Presurgical language fMRI in patients with drug-resistant epilepsy: effects of task performance.

PURPOSE To determine whether language functional magnetic resonance imaging (fMRI) before epilepsy surgery can be similarly interpreted in patients with greatly different performance levels. METHODS An fMRI paradigm using a semantic decision task with performance control and a perceptual control task was applied to 226 consecutive patients with drug-resistant localization-related epilepsy during their presurgical evaluations. The volume of activation and lateralization in an inferior frontal and a temporoparietal area was assessed in correlation with individual performance levels. RESULTS We observed differential effects of task performance on the volume of activation in the inferior frontal and the temporoparietal region of interest, but performance measures did not correlate with the lateralization of activation. CONCLUSIONS fMRI, as applied here, in patients with a wide range of cognitive abilities, can be interpreted regarding language lateralization in a similar way.