Altered grey matter integrity and network vulnerability relate to epilepsy occurrence in patients with multiple sclerosis

Background and purpose The aim of this study was to investigate the relevance of compartmentalized grey matter (GM) pathology and network reorganization in multiple sclerosis (MS) patients with concomitant epilepsy. Methods From 3-T magnetic resonance imaging scans of 30 MS patients with epilepsy (MSE group; age 41 +/- 15 years, 21 females, disease duration 8 +/- 6 years, median Expanded Disability Status Scale [EDSS] score 3), 60 MS patients without epilepsy (MS group; age 41 +/- 12 years, 35 females, disease duration 6 +/- 4 years, EDSS score 2), and 60 healthy subjects (HS group; age 40 +/- 13 years, 27 females) the regional volumes of GM lesions and of cortical, subcortical and hippocampal structures were quantified. Network topology and vulnerability were modelled within the graph theoretical framework. Receiver-operating characteristic (ROC) curve analysis was applied to assess the accuracy of GM pathology measures to discriminate between MSE and MS patients. Results Higher lesion volumes within the hippocampus, mesiotemporal cortex and amygdala were detected in the MSE compared to the MS group (all p < 0.05). The MSE group had lower cortical volumes mainly in temporal and parietal areas compared to the MS and HS groups (all p < 0.05). Lower hippocampal tail and presubiculum volumes were identified in both the MSE and MS groups compared to the HS group (all p < 0.05). Network topology in the MSE group was characterized by higher transitivity and assortativity, and higher vulnerability compared to the MS and HS groups (all p < 0.05). Hippocampal lesion volume yielded the highest accuracy (area under the ROC curve 0.80 [0.67-0.91]) in discriminating between MSE and MS patients. Conclusions High lesion load, altered integrity of mesiotemporal GM structures, and network reorganization are associated with a greater propensity for epilepsy occurrence in people with MS.

Automated summary

In patients with epilepsy, multiple sclerosis patients have larger lesion volumes in the hippocampus, mesiotemporal cortex, and amygdala, smaller cortical volumes, and higher network topology compared to healthy subjects. The volume of the hippocampus can be used to differentiate patients with epilepsy.