Abstracts

Rationale: The Anterior Temporal Lobectomy with Amygdalo-Hippocampectomy (ATL+AH) has been the primary surgical technique to treat patients with medically intractable Mesial Temporal Lobe Epilepsy (mTLE). While ATL has been proven to be successful in ceasing seizure activity, the resection of healthy eloquent cortex may cause neuropsychological dysfunction. To minimize the lesioning of eloquent cortex while maximizing seizure-freedom, laser interstitial thermal therapy-based amygdalo-hippocampectomy (LITT-AH) has become increasingly popular. Yet, there are few studies that have made formal comparisons between these two surgical approaches in regard to the impact on post-operative neuropsychological assessments, or on the patient’s epilepsy. Methods: We studied brain-behavior relationships in a sample (n = 60) of individuals that underwent surgery to treat mTLE. These patients underwent one of the following surgical techniques targeting components of the left antero-mesial temporal lobe: ATL (n = 10), ATL+AH, (n = 20), or LITT-AH (n = 30). All patients were assessed to be left-hemisphere dominant via a Wada test or using functional MRI. Pre- and post-operative behavioral and neuroimaging measures were conducted to measure pre-surgical differences and post-surgical functioning. The neuropsychological test battery included measures of verbal fluency, naming, and memory (semantic, verbal, and spatial). In each case, FreeSurfer software was utilized to derive cortical and subcortical segmentation using the pre-operative T1-weighted MRI. Resection volumes were outlined using the post-operative T1-weighted MRI and MRIcron software. Seizure outcomes were measured using Engel classification. Results: Engel outcomes were uncorrelated with the percentage of ablation of the mesial temporal structures. The impacts on the large neuropsychological test battery are being quantified and further correlated with the resected volumes. Change in error type pre- to post-surgery provide a structured representation of language. Conclusions: This study leverages a unique patient population for the comparison of ATL±AH and LITT-AH surgical techniques. Consequently, we can better quantify the functional organization of left language-dominant peri-Sylvian cortex and the impact ATL±AH and LITT-AH has on cognitive outcomes. The present research will inform future refinement of psycholinguistic models of language as well as provide insight towards surgical intervention of medically intractable mTLE. Funding: No funding was received in support of this abstract.