Abstracts

Rationale: Temporal lobe epilepsy (TLE) is the most common form of localization related epilepsy in which 30 to 40 percent of patients are considered pharmacoresistant. Recent literature suggests that amygdalectomy with minimal hippocampal resection can have positive results in seizure control rates in patients showing electrical discharges originating in the anterior temporal electrodes. The extent to which cognitive and affective processes are affected following amygdalectomy are less understood. These data report the neuropsychological outcome of this surgical technique. Methods: 8 patients with normal brain MRI underwent amygdalectomy with minimal hippocampal resection for medication refractory temporal lobe epilepsy in a large academic medical center. 8 additional demographically similar patients with normal brain MRI who underwent selective amygdalohippocamectomy were used as a comparison group. All participants had localization-related mesial temporal lobe epilepsy (MTLE) confirmed by long-term surface video-EEG and completed pre-surgical evaluations that included video-EEG, MRI, intracarotid methohexital test and neuropsychological assessment. All patients had both pre- and post-surgical neuropsychological studies. Results: There were no significant differences between the groups in demographic variables. Wilcoxen signed ranks tests found that patients having an amygdalectomy did not significantly decline on any neuropsychological measure. Alternatively, as a group, patients having a selective amygdalohippocampectomy had a significant decline in verbal memory [RAVLT immediate delay (p = .020) and RAVLT 30-minute delay (p = .018)] scores. Reliable change scores were calculated to determine the proportion of patients who show neuropsychological changes not due to prior test administration. Reliable decline was observed in 25% of amygdalectomy patients in confrontation naming. No other reliable changes were observed in the amygdalectomy group. 12.5% of patients who underwent selective amygdalohippocampectomy showed reliable decline in tasks of confrontation naming and immediate verbal recall. Additionally, in the same group, 25% of patients showed reliable decline in tasks of delayed verbal recall and visual memory. Conclusions: Neuropsychological outcome following successful resection of the amygdala while sparing hippocampal structures found no significant decline across neuropsychological measures for patients with TLE. Alternatively, patients who underwent selective resection of hippocampal and amygdala structures exhibited post-operative decline in immediate and delayed verbal memory. We conclude that amygdalectomy sparing hippocampus compares favorably to another mesial temporal lobe resection approaches in terms of neuropsychological outcome. Funding: none