Comparative localization of auditory comprehension by using functional magnetic resonance imaging and cortical stimulation

Object. The authors previously described a functional magnetic resonance (f MR) imaging task for the localization of auditory comprehension in which fo cal activation of posterior temporal and inferior frontal regions of the le ft hemisphere was reliably demonstrated. Because this study was conducted i n neurologically normal volunteers, it was not possible to determine whethe r the activated regions were critical to the performance of language tasks; that is, whether the fMR imaging activations provided a valid measure of l anguage processing. A direct comparison of fMR imaging language activation with cortical stimulation must be completed before it can be used with conf idence in presurgical planning, and this comparison is performed in the pre sent study. Methods. The authors report on a series of 33 consecutive patients who unde rwent dominant hemisphere resection and in whom fMR imaging mapping of audi tory comprehension was performed at the Yale neurosurgical program. In 23 of the 33 patients fMR imaging activation was consistent with the typ ical results obtained in normal participants in the earlier study. In 16 of these 23 patients language mapping was performed using either intra- or ex traoperative cortical stimulation. Cortical stimulation failed to localize language areas in two of the 16 patients. Electrical stimulation that was p erformed in proximity to the fMR image activations interfered with auditory comprehension, object naming, or speech production in 12 of the remaining 14 patients. Five of the 10 cases in which evocation of reliable fMR imagin g activation failed were attributable to technical problems and/or patient head movement. Conclusions. Cortical stimulation results and fMR imaging findings were con sistent in all but two patients. However, the spatial extent of the activat ion produced by fMR imaging and the spatial extent of stimulation-induced l anguage disruption that was caused by direct cortical stimulation did not a lways correspond. Problems in defining the extent of activation by both met hods are discussed.