Abstracts

RATIONALE: Antero-temporal lobectomy is the most common operative procedure used to treat epilepsy. It can be performed either as a standard resection (SR) or as a tailored resection (TR). Historically, epilepsy centers have adopted one but not both techniques. Current opinion holds that SR generally removes more tissue, especially from mesial and basal temporal lobe, and this results in a better seizure control. Data comparing seizure outcome in SR and TR have been difficult to interpret because centers differ not only with respect to choice of surgical technique, but also with respect to criteria for patient selection. For this reason we designed a two-center study comparing SR and TR in which patient selection at each center was the same. We focused on seizure outcome following SR or TR and correlated this outcome with the extent of temporal resection.
METHODS: We compared 30 SR patients and 30 TR patients. Each cohort had 15 patients with a left-sided focus and 15 with a right-sided focus. Each patient had a non-lesional unilateral antero-temporal seizure focus. The SR cohort received their care at the University of Wisconsin Epilepsy Program where at the time SR was the procedure of choice. The TR cohort received their care at the Rush Epilepsy Center where at the time TR was the procedure of choice. Patient selection was identical at each center. Achieving this objective was facilitated by the fact that the same epileptologist (AMK) held faculty positions at different times in both centers. The minimal follow-up period was seven years. Approximately six months after surgery patients underwent a brain MRI to establish the extent of temporal resection. To measure the extent of this resection we used Awad[ssquote]s semi-quantitative method (Epilepsia, 1989). We used Engel[ssquote]s classification to assess postsurgical seizure outcome (IA= no sz, no auras; IB, only auras; IC= sz after withdrawal of AED; ID = nocturnal sz; II = rare sz; III: [gt] 90% sz reduction; IV [lt] 90% sz reduction. Neuropathologic diagnosis was obtained for all patients. Logistic regression was used to test dichotomous variables and ANOVA was used to test continuous variables.
RESULTS: Patients who underwent SR had significantly greater tissue removal of mesial and basal structures than did patients who underwent TR (p=0.0001). Despite this, no significant difference in seizure outcome was seen between SR and TR when all patients in one cohort where compared as a group to those in the other cohort (see table). However, when the comparison was restricted to Class 1A alone (vs. IB+IC+ID+II+III+IV) there was a statistical trend favoring patients who underwent SR (p = 0.07).
CONCLUSIONS: Seven years following surgery to control anterotemporal epilepsy, the results of SR or TR are comparable, although there is a statistical trend favoring Class IA outcomes after SR. This trend maybe related to the fact that more mesial and basal temporal tissue is removed during SR than is removed in TR.[table1]