Abstracts

Rationale: There are few studies comparing the clinical outcomes after selective amygdalohippocampectomy (SAH) with those of the more commonly performed anterior temporal lobectomy (ATL). Prospective and retrospective studies suggest that adequate resection of the mesial temporal lobe structures plays an important role in seizure freedom. However, the utility of resection of other temporal lobe structures remains unclear. Methods: The Epilepsy Surgery Database at the Washington University School of Medicine Epilepsy Center and the neurosurgery database were searched for subjects who had undergone SAH and ATL between 1998 and 2008. Inclusion criteria were adult patients over 18 years of age and the use of intracranial EEG monitoring to localize seizure onset prior to resection. ATL cases were included by selection of consecutive cases performed by neurosurgeon JGO. ATL cases were then matched for clinical characteristics with subjects who underwent SAH by neurosurgeon JLD. The clinical outcomes included complications, days of hospital stay, seizure frequency and seizure severity scale rating before and 2 years after epilepsy surgery (or at the last follow up date if earlier than 2 years postoperatively). A “Seizure Frequency Scoring System” scale was used to score seizure frequency (Seizure free off AEDs = 0 up to SE without barbiturate coma = 12). The averages and standard deviations were calculated for each group, and the groups were compared using 2-tailed T tests and Fisher’s exact test. Results: Twenty-one patients were identified in each surgical group comprising a total of 42 patients. Patients in the ATL group were of an average age of 31, had a 16 year history of seizures, and averaged 9.3 seizures per month. In the SAH group, the average age was 37, with a 15 year history of seizures, and an average of 7 seizures per month. Outcome measurement was post-op seizure severity, which decreased from 8 to 4, and 8 to 3 in the ATL and selective groups, respectively. The surgical procedure had no significant difference in seizure outcome (p=0.218). The SAH group had an absolute reduction of post-op hospital days of 0.8 (2.1 vs. 1.3, p=0.0008). Eight patients had complications in the ATL group and four patients had complications in the SAH group (p=0.153). Conclusions: Both selective amygdalohippocampectomy and anterior temporal lobectomy provide equivalent seizure control in patients with mesial temporal lobe epilepsy. The transcortical, selective approach was associated with a significant reduction in hospital stay and showed a trend toward fewer post-operative complications.