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Midbrain structure volume, estimated myelin and functional connectivity in idiopathic generalised epilepsy

Lookup NU author(s): Dr Peter TaylorORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2023 The Author(s) Background: Structural and functional neuroimaging studies often overlook lower basal ganglia structures located in and adjacent to the midbrain due to poor contrast on clinically acquired T1-weighted scans. Here, we acquired T1-weighted, T2-weighted, and resting-state fMRI scans to investigate differences in volume, estimated myelin content and functional connectivity of the substantia nigra (SN), subthalamic nuclei (SubTN) and red nuclei (RN) of the midbrain in IGE. Methods: Thirty-three patients with IGE (23 refractory, 10 non-refractory) and 39 age and sex-matched healthy controls underwent MR imaging. Midbrain structures were automatically segmented from T2-weighted images and structural volumes were calculated. The estimated myelin content for each structure was determined using a T1-weighted/T2-weighted ratio method. Resting-state functional connectivity analysis of midbrain structures (seed-based) was performed using the CONN toolbox. Results: An increased volume of the right RN was found in IGE and structural volumes of the right SubTN differed between patients with non-refractory and refractory IGE. However, no volume findings survived corrections for multiple comparisons. No myelin alterations of midbrain structures were found for any subject groups. We found functional connectivity alterations including significantly decreased connectivity between the left SN and the thalamus and significantly increased connectivity between the right SubTN and the superior frontal gyrus in IGE. Conclusions: We report volumetric and functional connectivity alterations of the midbrain in patients with IGE. We postulate that potential increases in structural volumes are due to increased iron deposition that impacts T2-weighted contrast. These findings are consistent with previous studies demonstrating pathophysiological abnormalities of the lower basal ganglia in animal models of generalised epilepsy.

Publication metadata

Author(s): McKavanagh A, Ridzuan-Allen A, Kreilkamp BAK, Chen Y, Manjon JV, Coupe P, Bracewell M, Das K, Taylor PN, Marson AG, Keller SS

Publication type: Article

Publication status: Published

Journal: Epilepsy and Behavior

Year: 2023

Volume: 140

Print publication date: 01/03/2023

Online publication date: 24/01/2023

Acceptance date: 01/01/2023

Date deposited: 09/02/2023

ISSN (print): 1525-5050

ISSN (electronic): 1525-5069

Publisher: Academic Press


DOI: 10.1016/j.yebeh.2023.109084

PubMed id: 36702054


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