Brain Atrophy May Help Predict Surgical Outcomes in Mesial Temporal Lobe Epilepsy With Hippocampal Sclerosis

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Atrophy in areas outside of the MTLE-HS network may predict poor surgical outcomes.
Atrophy in areas outside of the MTLE-HS network may predict poor surgical outcomes.

HOUSTON – Atrophy in the entorhinal cortex and parahippocampal gyrus may indicate patients with refractory mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) who may have poor seizure outcomes after corticoamygdalohippocampectomy (CAH).

While approximately two-thirds of patients with MTLE-HS who undergo CAH become seizure free, a third of patients continue to experience seizures.

In order to examine whether atrophy in other regions of the brain affect the epileptogenic network in MTLE-HS, Maria Teresa Garcia, MD, of the Universidade Federal de Sao Paulo in Brazil, and colleagues used MRI quantitative imaging to measure cortical thickness and volumetric estimation in patients undergoing CAH. The results of their research were presented at the 2016 American Epilepsy Society Annual Meeting.

In total, 105 patients (46 male; 59 left-MTLE) with refractory MTLE-HS underwent CAH. The final analysis included 99 patients and 47 controls. Analyses of cortical thickness showed decreased volume in the left insula in patients with MTLE-HS vs controls. In patients who were seizure-free postoperatively, significant reductions in volume were observed in the bilateral thalami, hippocampi and pars opercularis, left parahippocampus, and right temporal pole. Patients who were not seizure free postoperatively showed reductions bilaterally in the thalami, hippocampi, entorhinal cortices, superior frontal and supramarginal gyri; on the left in the superior and middle temporal gyri, temporal pole, parahippocampus, pars opercularis, and middle frontal gyrus; and on the right in the precentral, superior, middle, and inferior temporal gyri. Compared with patients who were seizure free, patients with right MTLE-HS who continued to experience seizures exhibited ipsilateral reductions in gray matter in the right entorhinal cortex (P= .003) and contralateral parahippocampal gyrus (P= .05). Notably, patients who were not seizure free postoperatively had a longer history of epilepsy (P= .028).

The results suggest that volumetric reductions in the entorhinal cortex and parahippocampal gyrus may be indicative of poor outcomes after CAH. Preoperative MRI may help identify these abnormalities within and outside of the MTLE-HS network, in turn providing more prognostic information for patients with MTLE-HS who plan to undergo CAH.

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Reference

Garcia M, Gaça L, Sandim G, et al. Cortical thickness and morphometric analyses as predictors of seizure outcome after surgery in mesial temporal lobe epilepsy with hippocampal sclerosis. Presented at: 2016 American Epilepsy Society Annual Meeting; December 2-6, 2016; Houston, TX. Abstract 2.110.

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