Abstracts

RATIONALE: Circumscribed lesions of the language-dominant temporal lobe may lead to significant selective naming dysfunction. Surgery for medically intractable dominant temporal lobe epilepsy (TLE) aims to remove the epileptogenic focus but may lead to naming difficulties. Our objective was to correlate the extent of anatomical resection with naming outcome following temporal lobe resection in patients with a history of drug resistant TLE. At the end of this activity the participants should be able to discuss the relationship between temporal lobectomy and naming outcome.
METHODS: We retrospectively reviewed the post-operative MRI-scans of 163 patients who underwent temporal lobe resection for medically intractable TLE (between 1990 and 2000). The linear extent of resection of the superior (T1), middle (T2), and inferior (T3) temporal gyri, the fusiform gyrus (FUS), parahippocampal gyrus (PHG), hippocampus (HIP) and amygdala (AMG) was measured. All patients were left hemisphere language-dominant as determined by amobarbital testing (WADA). The extent of resection of each region was correlated with the postoperative Boston Naming Test (BNT) outcome. Z-scores were calculated based on the expected changes due to practice effects in a group of normal controls.
RESULTS: Seventy-three patients underwent surgery for right TLE and 90 had surgery for left TLE. The groups were comparable with regards to demographic variables. There were no significant changes in BNT Z-scores following right temporal lobectomy. Patients who underwent left-sided resection showed an average BNT Z-score decrease of [ndash]1.15 (n=90). Patients with complete left hippocampal resection (n=18; Z-score [ndash]2.33; SD 2.34) had a significantly more severe drop in their BNT Z-scores than patients without hippocampal resection (n=10; Z-score [ndash]0.19; 1.84, p[lt]0.019). To investigate the relative contributions of variable amounts of resected temporal gyri, a stepwise multiple regression analysis was performed. This analysis revealed that the amount of hippocampal resection of the language-dominant hemisphere was significantly related to a decrease in BNT Z-scores (R= -0.266; p=0.011). Interestingly, a slightly better predictor of language outcome was the multiplicative hippocampus-fusiform gyrus interaction. This means that the combined extent of resection of these gyri was even more strongly associated with postoperatively impaired naming function.(R= 0.280; p[lt]0.001).
CONCLUSIONS: Naming deficits appear to occur only following dominant temporal lobe surgery. The resection of the dominant side hippocampus is associated with significant naming decrements. The interaction of fusiform gyrus and hippocampus improved the predictive power of postoperative naming dysfunction in patients who are undergoing dominant mesial temporal lobe surgery.