Abstracts

Rationale: The subtemporal approach for selective amygdalohippocampectomy (SelAH) is a surgical approach for the treatment of medically refractory mesial temporal lobe epilepsy (mTLE) that minimizes damange to the lateral temporal cortex and temporal stem. We present the seizure outcomes and surgical mortality and morbidity for the largest series of temporal lobe epilepsy patients treated via a subtemporal SelAH. Methods: This is a retrospective observational study. The sample included patients with medically refractory mTLE treated via subtemporal SelAH by the senior author at the Barrow Neurological Institute from 2004 to 2016. Patients with prior epilepsy surgery, resections in addition to a subtemporal SelAH, or a diagnosis of diffuse glioma, were excluded. We report seizure outcomes using the Engel classification, as well as surgical mortality, major morbidity, and anti-epileptic drug (AED) cessation. Patient characteristics, including gender, age, date of surgery, presence of mesial temporal sclerosis on MRI, presence of hippocampal sclerosis on pathology, use of invasive monitoring prior to SelAH, and operative side, were evaluated to determine if they would predict seizure outcome. Results: A total of 212 patients were identified with an average follow-up of 3.33 years. There were no deaths related to surgery and the major morbidity rate was 4.7%. Of those patients at least 1 year out from surgery (n=208), 73.1% (n=152) had at least 1 year of follow-up. For the patients with at least 1 year follow-up, 57.9% (n=88) had an Engel class I seizure outcome, with 25.7% (n=39) Engel class II, 9.9%  (n=15) Engel class III, and 6.6% (n=10) Engel class IV.  On univariate analysis, patients were statistically more likely to achieve an Engel class I seizure outcome at 1 year if they did not require invasive monitoring prior to SelAH (p=0.005) and if they had mesial temporal sclerosis (MTS) on MRI (p=0.016). Of patients with MTS on MRI and who did not require invasive monitoring ("skip candidates"), 68.4% had an Engel class I outcome. None of the patient characteristics were significant predictors of seizure outcome on multivariate analysis. Of the patients with Engel class I seizure outcome, only 26.1% (n=23) were off AEDs at last follow-up. Conclusions: Our series of patients treated via subtemporal selective amygdalohippocampectomy for medically refractory mesial temporal lobe epilepsy demonstrated good seizure outcomes with no deaths and a low rate of major morbidity. Funding: None