Abstracts

Rationale: Naming decline is a well-known risk of dominant hemisphere epilepsy surgery in adults; however, postoperative naming outcome for children has been less definitive. The few studies that have examined postoperative naming have shown mixed results, with reports of naming improvement, no change, as well as decline. We suspect these inconsistencies have been due to 1) use of less sensitive adult measures to assess naming in children, and 2) failure to examine naming separately in children who had dominant vs nondominant surgery. We recently developed and standardized auditory (ANT) and complementary visual naming tests (VNT) for children, which show sensitivity to left (dominant) hemisphere epileptogenicity. Our aim was to use these more valid measures to identify factors that influence postoperative naming in children who undergo left (dominant) and right (nondominant) hemisphere surgery for refractory epilepsy. Our hypothesis was, like adults, naming would decline following left, but not right hemisphere resection.

Methods: Participants were 31 children (15 girls) with refractory epilepsy (18 left hemisphere, 13 right hemisphere), tested pre- and 1-2 years postoperatively (left: age: 11.7 ± 2.7, FSIQ: 88.4 ±7.4; right: age: 12.4 ± 2.6, FSIQ: 95.2, ± 12.7), with evidence of left hemisphere language dominance based on fMRI (n=14), right handedness and/or neuropsychological profile (n = 10), dichotic listening (n=2), or Wada testing (n=1). All children were administered the Children’s ANT and VNT. ANT and VNT scores were converted to Z-scores using age-stratified normative data. For both tests, performance consisted of Tip-of-the-tongue scores (“TOT” = items named 2-20 seconds or after 20 seconds following a phonemic cue, i.e., hallmark feature of naming difficulty). Independent sample T-tests compared groups preoperatively and paired T-tests compared pre and postoperative ANT and VNT performance.

Results: As predicted, no naming changes were found following right hemisphere surgery; however, counter to expectations, naming appeared unchanged following left hemisphere surgery as well. Further analysis found no consistent findings related age, age of epilepsy onset, seizure onset region, or number of anti-seizure medications. However, girls were found to have stronger preoperative naming performance (VNT TOT: t = -2.3, P = .03; ANT TOT: t = -1.6, P = .12); and girls, but not boys, showed significant postoperative decline in visual naming (VNT TOT: t = -3.1, P = .02). No sex effects were evident in children who underwent right hemisphere surgery.

Conclusions: These preliminary results found stronger preoperative visual naming performance among girls compared to boys with left hemisphere refractory epilepsy, and greater postoperative decline. Unfortunately, girls’ initial advantage does not appear to be protective; rather, it renders them more vulnerable to decline, likely related to removal or disruption of less compromised brain tissue. Our future work aims to expand the sample to determine the reliability of this finding, and to identify other factors that influence postoperative naming.

Funding: Please list any funding that was received in support of this abstract.: NIH R01 NS35140 (MH).