Abstracts

Corticoamygdalohippocampectomy (CAH) and selective amygdalohippocampectomy (AHE) are two approaches to the surgical treatment of temporal lobe epilepsy. While CAH involves removal of the anterior temporal neocortex, amygdala and anterior hippocampus, AHE consists of a resection focused on the medial temporal structures, and is considered potentially less damaging since it achieves good seizure control while sparing the neocortex.
Given the critical role of the mediotemporal structures in memory, previous studies comparing the neuropsychological outcome of these two procedures have focused on memory function, and found little or no impact of resection type. The aim of the present study was to compare the effect of CAH and AHE on nonmemory cognitive functions, to gain a more complete understanding of the relative advantages and disadvantages of these procedures., We studied data from patients with a clearly lateralized temporal-lobe epileptic focus, who underwent neuropsychological evaluation following either AHE or CAH. Patients were between 16 and 60 years old, with IQ [gt] 75, right-handed with left hemisphere speech dominance. Neuropsychological measures included WAIS-R IQ and, as nonverbal measures, the Block Design and Digit Symbol standardized subscale scores, plus five verbal tasks: Boston Naming Test, Token Test, Chicago Word Fluency test, Chapman-Cook Speed of Reading test and expanded digit span. We compared scores as a function of laterality of epileptic focus (left temporal, LT; right temporal, RT) and type of excision (CAH or AHE)., Patient groups proved to be well matched on preoperative IQ, and there were no preoperative differences by eventual excision type on any measure. However, there was one preoperative laterality difference: LT patients performed less well than RT patients on the Boston Naming Test. Postoperative differences were observed on several measures. LT patients were again impaired on naming, and they produced fewer words than did RT patients on the Word Fluency test. Differences according to excision type were also observed: left CAH patients showed significantly poorer naming than any other group. CAH patients produced fewer words on the Word Fluency test and read fewer passages on the Chapman-Cook test than did AHE patients. No differences were found on the nonverbal tasks., Patients who underwent CAH displayed poorer performance after surgery on several nonmemory verbal cognitive measures, whereas patients with SAH were not poorer than CAH patients on any measure. These results suggest that sparing the temporal neocortex produces smaller postoperative deficits on certain nonmemory cognitive functions., (Supported by Canadian Institutes of Health Research.)