Anatomic distribution of cortical language sites in the basal temporal language area in patients with left temporal lobe epilepsy.

In evaluation for surgical treatment of intractable psychomotor seizures originating in the language-dominant left mesiotemporal region, subdural grid electrodes were placed in 29 patients over the temporoparietal cortex and over the basotemporal region. In 13 patients, cortical stimulation of the basotemporal region showed interference with language processing. The most anterior border of the basotemporal language area began 1.1 cm posterior to the anterotemporal tip, and the most posterior margin of the language region was located 6.1 cm posterior to the temporal tip. The most lateral and the most mesial border were located 1.4 and 5.9 cm, respectively, from the lateral edge of the temporal lobe. The region in which language disturbance could be elicited included the inferior temporal gyrus, the fusiform (lateral and medial occipitotemporal) gyrus, and the parahippocampal gyrus. The basotemporal area most consistently involved with language function was the fusiform gyrus (60% of affected electrodes), followed by the inferotemporal (30%), and the parahippocampal (10%) gyri.