Posterior extent of left anterior temporal lobectomy and picture naming decline

Recent voxel-based lesion symptom mapping (VLSM) studies have identified a critical region for picture naming, located 3.4 to 6.1 cm from the temporal pole. Its resection during left temporal lobe epilepsy surgery led to postoperative decline in picture naming. However, postoperative anomia has been reported after classic left temporal lobectomy, which rarely extends so posteriorly. The aim of the present study was to evaluate patients' postoperative picture naming outcome on the basis of their precise surgical cavities in light of the recent findings from VLSM studies.

In this monocentric retrospective study, the authors analyzed picture naming outcome and the surgical cavities of 34 patients who underwent surgery for left temporal lobe epilepsy. The authors evaluated their cohort's surgical cavities on the basis of the critical regions identified by VLSM studies as essential to picture naming.

The surgical cavities of patients were anterior to the critical regions for picture naming identified by VLSM studies in the literature. Eight of 11 patients with postoperative lexical access decline at 18 months had a posterior limit of the lesioned voxels that did not reach the critical region identified by VLSM studies. Only 3 of 11 patients with a postoperative picture naming decline had surgical cavities reaching these critical regions. Conversely, 3 of 23 patients with stable or improved postoperative picture naming had surgical cavities reaching these critical regions.

Keeping a surgical cavity anterior to the limits identified by recent VLSM studies does not protect patients from postoperative picture naming decline. Interindividual anteroposterior variability of the basal temporal language area could complete the explanation offered by VLSM.