Region-specific MRI predictors of surgical outcome in temporal lobe epilepsy

• Published in: NeuroImage clinical Vol. 43; p. 103658
• Main Authors: Fadaie, Fatemeh, Caldairou, Benoit, Gill, Ravnoor S., Foit, Niels A., Hall, Jeffery A., Bernhardt, Boris C., Bernasconi, Neda, Bernasconi, Andrea
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.01.2024; Elsevier
• Subjects: Radiology; Regular
• ISSN: 2213-1582; 2213-1582
• DOI: 10.1016/j.nicl.2024.103658

•Seizure-free TLE patients have more severe pre-op mesiotemporal atrophy.•Hippocampal atrophy and its resection extent predict seizure freedom in 89% of cases.•Post-operative MRI anomalies do not affect surgical outcome. In drug-resistant temporal lobe epilepsy (TLE), it is not well-established in how far surgery should target morphological anomalies to achieve seizure freedom. Here, we assessed interactions between structural brain compromise and surgery to identify region-specific predictors of seizure outcome. We obtained pre- and post-operative 3D T1-weighted MRI in 55 TLE patients who underwent selective amygdalo-hippocampectomy (SAH) or anterior temporal lobectomy (ATL) and 40 age and sex-matched healthy subjects. We measured surface-based morphological alterations of the mesiotemporal lobe structures (hippocampus, amygdala, entorhinal and piriform cortices), the neocortex and the thalamus on both pre- and post-operative MRI. Using precise co-registration, in each patient we mapped the surgical cavity onto the MRI acquired before surgery, thereby quantifying the amount of pathological tissue resected; these features, together with the preoperative morphometric data, served as input to a supervised classification algorithm for postsurgical outcome prediction. On pre-operative MRI, patients who became seizure-free (TLE-SF) presented with severe ipsilateral amygdalar and hippocampal atrophy, while not seizure-free patients (TLE-NSF) displayed amygdalar hypertrophy. Stratifying patients based on the surgical approach, post-operative MRI showed similar patterns of mesiotemporal and thalamic changes, but divergent neocortical thinning affecting the parieto-temporo-occipital regions following ATL and the frontal lobes after SAH. Irrespective of the surgical approach, hippocampal atrophy on pre-operative MRI and its extent of resection were the most predictive features of seizure-freedom in 89% of patients (selected 100% across validations). Our study indicates a critical role of the extent of resection of MRI-derived hippocampal morphological anomalies on seizure outcome. Precise pre-operative quantification of the mesiotemporal lobe provides non-invasive prognostics for individualized surgery.