Hippocampal Atrophy Is Associated with Altered Hippocampus–Posterior Cingulate Cortex Connectivity in Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis
Journal
American Journal of Neuroradiology
Journal Volume
38
Journal Issue
3
Pages
626
Date Issued
2017
Author(s)
Abstract
Background and Purpose: Unilateral mesial temporal lobe epilepsy and hippocampal sclerosis have structural and functional abnormalities in the mesial temporal regions. To gain insight into the pathophysiology of the epileptic network in mesial temporal lobe epilepsy with hippocampal sclerosis, we aimed to clarify the relationships between hippocampal atrophy and the altered connection between the hippocampus and the posterior cingulate cortex in patients with mesial temporal lobe epilepsy with hippocampal sclerosis. MATERIALS AND METHODS: Fifteen patients with left mesial temporal lobe epilepsy with hippocampal sclerosis and 15 healthy controls were included in the study. Multicontrast MR imaging, including high-resolution T1WI, diffusion spectrum imaging, and resting-state fMRI, was performed to measure the hippocampal volume, structural connectivity of the inferior cingulum bundle, and intrinsic functional connectivity between the hippocampus and the posterior cingulate cortex, respectively. RESULTS: Compared with controls, patients had decreased left hippocampal volume (volume ratio of the hippocampus and controls, 0.366% ± 0.029%; patients, 0.277% ± 0.063%, corrected P <.002), structural connectivity of the bilateral inferior cingulum bundle (generalized fractional anisotropy, left: controls, 0.234 ± 0.020; patients, 0.193 ± 0.022, corrected P <.0001, right: controls, 0.226 ± 0.022; patients, 0.208 ± 0.017, corrected P <.047), and intrinsic functional connectivity between the left hippocampus and the left posterior cingulate cortex (averaged z-value: controls, 0.314 ± 0.152; patients, 0.166 ± 0.062). The left hippocampal volume correlated with structural connectivity positively (standardized ± < 0.864, P <.001), but it had little correlation with intrinsic functional connectivity (standardized ± <-0.329, P <.113). On the contralesional side, the hippocampal volume did not show any significant correlation with structural connectivity or intrinsic functional connectivity (F2,12 < 0.284, P <.757, R2 < 0.045). CONCLUSIONS: In left mesial temporal lobe epilepsy with hippocampal sclerosis, the left inferior cingulum bundle undergoes degeneration in tandem with the left hippocampal volume, whereas intrinsic functional connectivity seems to react by compensating the loss of connectivity. Such insight might be helpful in understanding the development of the epileptic network in left mesial temporal lobe epilepsy with hippocampal sclerosis.
SDGs
Other Subjects
adult; brain atrophy; brain size; cingulum (brain); clinical article; Conference Paper; controlled study; disease association; functional connectivity; functional magnetic resonance imaging; functional neuroimaging; hippocampal sclerosis; hippocampus; human; male; mesial temporal lobe epilepsy; neuropathology; nuclear magnetic resonance scanner; posterior cingulate; atrophy; brain mapping; cingulate gyrus; diagnostic imaging; diffusion weighted imaging; female; hemispheric dominance; hippocampus; image processing; middle aged; nerve tract; nuclear magnetic resonance imaging; pathology; sclerosis; temporal lobe epilepsy; Adult; Atrophy; Brain Mapping; Diffusion Magnetic Resonance Imaging; Epilepsy, Temporal Lobe; Female; Functional Laterality; Gyrus Cinguli; Hippocampus; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Middle Aged; Neural Pathways; Sclerosis
Publisher
American Society of Neuroradiology ({ASNR})
Type
journal article