COGNITIVE EFFECTS OF RESECTING BASAL TEMPORAL LANGUAGE AREAS

Electrical stimulation of the basal temporal region of the dominant he misphere before partial temporal lobectomy for epilepsy sometimes prod uces temporary interruption of language function, but the significance of removal of this area is unknown. We evaluated the correlation betw een resection of the basal temporal language areas (BTLA) and certain types of postoperative language deficits. In a population of 25 patien ts, we mapped the inferolateral temporal lobe with cortical electrical stimulation, verifying the positions of the stimulating electrodes wi th three-dimensional computed tomography (CT). Eighty percent of the p atients developed transient language deficits with stimulation, partic ularly with tests of confrontation naming and comprehension. BTLA was primarily located in the fusiform gyrus, from 1 to 9 cm from the tempo ral tip. At testing 6-12 months after operation, patients with BTLA re section performed worse (mean 9% decrease) than those with no BTLA res ection (mean 4% improvement) on tests of confrontation naming (p = 0.0 3). Resection size accounted for less of the variance in decrease in c onfrontation naming than did resection of the BTLA. Tests of performan ce T.Q. (PIQ), verbal I.Q. (VIQ), or recognition memory for word and v erbal learning showed no significant difference between these groups. Most patients do not have language decrease with removal of basal temp oral lobe 5-6 cm from the tip, even with removal of BTLA. Some patient s, however, have persistent decrease in naming.