MRI network progression in mesial temporal lobe epilepsy related to healthy brain architecture

Abstract

We measured MRI network progression in mesial temporal lobe epilepsy (mTLE) patients as a function of healthy brain architecture. Resting state functional MRI and diffusion-weighted MRI were acquired in 40 unilateral mTLE patients and 70 healthy controls. Data were used to construct region-to-region functional connectivity, structural connectivity and streamline length connectomes per subject. Three models of distance from the presumed seizure focus in the anterior hippocampus in the healthy brain were computed using the average connectome across controls. A fourth model was defined using regions of transmodal (higher cognitive function) to unimodal (perceptual) networks across a published functional gradient in the healthy brain. These models were used to test whether network progression in patients increased when distance from the anterior hippocampus or along a functional gradient in the healthy brain decreases. Results showed that alterations of structural and functional networks in mTLE occur in greater magnitude in regions of the brain closer to the seizure focus based on healthy brain topology, and decrease as distance from the focus increases over duration of disease. Overall, this work provides evidence that changes across the brain in focal epilepsy occur along healthy brain architecture.

Advanced neuroimaging techniques in epilepsy

“…At this time, the causal relationship of drug responsiveness and diffusion changes is not clear. Abnormalities of structural and functional connectivity were shown to be more marked closer to the presumed seizure onset zone, consistent with the findings of the ENIGMA study [15]. A consistent finding was that functional connectivity parameters were more abnormal in those with TLE and hippocampal sclerosis than those without hippocampal sclerosis [16].…”

Presurgical temporal lobe epilepsy connectome fingerprint for seizure outcome prediction

“…All subjects underwent the same imaging procedure on a 3 Telsa MRI scanner with a 32-channel head coil (Philips Healthcare, Best, Netherlands). As in our previous work, 28 the image acquisition included the following: (i) T 1 -weighted MRI for inter-subject normalization and regional and tissue segmentation (1 × 1 × 1 mm), (ii) T 1 -weighted MRI acquired in the same slice orientation as the functional images (1 × 1 × 3.5 mm with 0.5 mm gap), (iii) functional T 2 *-weighted MRI at rest with eyes closed (34 axial slices, echo time = 35 ms, repetition time = 2 sec, 3 × 3 × 3.5 mm with a 0.5 mm gap, 10 min), (iv) diffusion MRI for structural connectivity (50 slices, 2.5 × 2.5 × 2.5 mm, 92 directions, b = 0, 1600 s/mm 2 ). Cardiac and respiratory fluctuations were recorded at 500 Hz using the scanner integrated pulse oximeter and respiratory belt.…”

“…Preprocessing and connectome development followed procedures published previously 28 and reiterated here. The functional MRI images were preprocessed using SPM12 software ( http://www.fil.ion.ucl.ac.uk/spm/software/spm12/ ) and MATLAB 2019a (The MathWorks, Inc, Natick, MA).…”

Network dysfunction in pre and postsurgical epilepsy: connectomics as a tool and not a destination

“…Does the clinician need to consider disease duration when making treatment decisions? Morgan et al modeled healthy brain structural and functional network progression during aging, then used this framework to observe exacerbated network changes along the model gradient in patients with mesial TLE compared to healthy controls [22]. Specifically, their evidence suggests that functional connectivity changes as measured by fMRI are three times greater in magnitude than structural connectivity changes radiating from the anterior hippocampus.…”