Language dominance determined by whole brain functional MRI in patients with brain lesions

Background: Functional MRI (fMRI) is of potential value in determining hemi sphere dominance for language in epileptic patients. Objective: To develop and validate an fMRI-based method of determining language dominance for pat ients with a nide range of potentially operable brain lesions in addition t o epilepsy. Methods: Initially, a within-subjects design was used with 19 h ealthy volunteers (11 strongly right-handed, 8 left-handed) to determine th e relative lateralizing usefulness of three different language tasks in fMR I. An automated, hemispheric analysis of laterality was used to analyze who le brain fMRI data sets. To evaluate the clinical usefulness of this method , we compared fMRI-determined laterality with laterality determined by Wada testing or electrocortical stimulation mapping, or both, in 23 consecutive patients undergoing presurgical evaluation of language dominance. Results: Only the verb generation task. was reliably lateralizing, fMRI, using the verb generation task and an automated hemispheric analysis method, was conc ordant with invasive measures in 22 of 23 patients (12 Wada, 11 cortical st imulation). For the single patient who was discordant, in whom a tumor invo lved one-third of the left hemisphere, fMRI became concordant when the tumo r and its reflection in the right hemisphere were excluded from laterality analysis. No significant negative correlation was obtained between lesion s ize and strength of laterality for the patients with lesions involving the dominant hemisphere. Conclusion: This fMRI method shows potential for evalu ating language dominance in patients with a variety of brain lesions.