Abstracts

Rationale: The efficacy of selective amygdalohippocampectomy (SelAH) in well-selected cases of pediatric medically refractory unilateral temporal lobe epilepsy (TLE) remains controversial. Limited and divergent literature exists with relatively brief postoperative follow up. The primary objective of this study was to compare the surgical outcome and the rate of reoperation for ongoing or recurrent seizures between SelAH and anterior temporal lobectomy (ATL) in pediatric TLE. The secondary objective was to evaluate neuropsychological performance after initial and any subsequent ipsilateral procedures.  Methods: Retrospective review of pediatric TLE patients referred to the Epilepsy Program at our institution between 1988 and 2015 treated initially with either a trans-middle temporal gyrus SelAH or ATL. Patients underwent a standardized pre- and post-operative evaluation including seizure charting, surface and long-term video electroencephalography, 1.5-T MRI and neuropsychological testing. The neuropsychological battery included Wechsler Adult Intelligence Scale III (full-scale, verbal comprehension, perceptual organization), verbal memory tests (story memory and Rey Auditory Visual Learning Test) and non-verbal memory (picture memory, design memory and Rey-Osterrieth complex figure). Postoperative seizure outcome was categorized using the modified Engel classification. Results: Preoperative characteristics are summarized in Table 1. A total of 79 patients treated initially with SelAH (n=18) or ATL (n=61) were included in this study, with mean follow-up of 5.3 ± 4 years (range, 1 – 16). The average age at initial surgery was 10.6 ± 5 years with an average surgical delay of 5.7 ± 4 years between seizure onset and surgery. Seizure freedom (Engel I) following initial operation was significantly more likely following ATL (47/61; 77%) than SelAH (8/18; 44%, p=0.017, Fisher’s exact test; Figure 1). Neuropsychological testing was available pre- and post-operatively in 29 patients (SelAH-8; ATL-21) with an average delay 12 ± 5 months after surgery. There were no statistically significant postoperative deficits following either SelAH or ATL. However, reoperation was significantly more likely following SelAH (8/18; 44%) compared to ATL (7/61; 11%, p=0.004). Reoperation was more likely to result in Engel I outcome for ATL after failed SelAH (7/8, 88%) than posterior extension after failed ATL (1/7, 14%; p=0.01). Reoperation was well tolerated without significant neuropsychological deterioration. Ultimately, including 15 reoperations, 58/79 (73%) patients were free from disabling seizures at most recent follow up. Conclusions: SelAH amongst well-selected pediatric patients with medically refractory unilateral TLE yields significantly worse rates of seizure control compared with ATL. Reoperation is significantly more likely following SelAH, is not associated with incremental neuropsychological deterioration and frequently results in freedom from disabling seizures. These results are significant in that they argue against using SelAH for pediatric TLE surgery.  Funding: This work was supported by a Killam Trust Doctoral Scholarship (CAE) and the Clinical Investigator Program (CAE) at the University of Alberta.