Abstracts

Rationale: Selective amygdalohippocampectomy (SAH) is an accepted alternative for the surgical treatment of mesial temporal lobe epilepsy (MTLE). Reports suggest a potential cognitive benefit of SAH over standard temporal lobectomy. We present the cognitive outcome after SAH performed on a consecutive cohort of patients at the Calgary Epilepsy Program. Methods: A retrospective analysis of all adult patients who underwent transcortical SAH using image and intraoperative MRI guidance was completed. Kaplan-Meier curve was plotted for seizure freedom. Pre- and post-operative cognitive performances (IQ, verbal and visual memory, working memory and language) were compared using reliable change index values. Results: 83 patients were operated for SAH in the last ten years at the Foothills Medical Center. Complete pre- and post-operative neuropsychological evaluations were available for 53 patients (29 left side, 24 right side). Average age at surgery was 37 years ( /- 9). Seizure freedom was obtained in 65% of patients, and good outcome (Engel I or II) in 83%. There was no significant post-operative change in IQ or working memory. Visual memory (WMS III Delayed Visual Index) declined in 23% of patients operated on the right compared to 11% for left side operations. Verbal memory (WMS III Delayed Verbal Index) declined in 11% of patients operated on the left compared to 9% for right side operations. California Verbal Learning Test (CVLT) was more sensitive for detecting a post-operative verbal memory decline: 29% for left sided operations and 23% for right-sided. Naming (Boston Naming Test) deteriorated in 39% after left SAH compared to 4% after right operations. Conclusions: Selective amygdalohippocampectomy is an effective treatment for the long-term control of intractable MTLE. Overall, memory changes were equivalent to or lower than rates reported for standard temporal lobectomy. However naming decline following SAH was similar to most series of standard temporal lobectomy. Because lateral neocortex is largely preserved in SAH, this may indicate an important role for mesial temporal structures in language. Alternatively, cortical disruption of the middle temporal gyrus may be resposible for naming changes after SAH