Altered structural connectome in temporal lobe epilepsy.
OBJECTIVE
To study differences in the whole-brain structural connectomes of patients with left temporal lobe epilepsy (TLE) and healthy control subjects.


METHODS
This study was approved by the institutional review board, and all individuals gave signed informed consent. Sixty-direction diffusion-tensor imaging and magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) magnetic resonance imaging volumes were analyzed in 24 patients with left TLE and in 24 healthy control subjects. MP-RAGE volumes were segmented into 1015 regions of interest (ROIs) spanning the entire brain. Deterministic white matter tractography was performed after voxelwise tensor calculation. Weighted structural connectivity matrices were generated by using the pairwise density of connecting fibers between ROIs. Graph theoretical measures of connectivity networks were compared between groups by using linear models with permutation testing.


RESULTS
Patients with TLE had 22%-45% reduced (P < .01) distant connectivity in the medial orbitofrontal cortex, temporal cortex, posterior cingulate cortex, and precuneus, compared with that in healthy subjects. However, local connectivity, as measured by means of network efficiency, was increased by 85%-270% (P < .01) in the medial and lateral frontal cortices, insular cortex, posterior cingulate cortex, precuneus, and occipital cortex in patients with TLE as compared with healthy subjects.


CONCLUSIONS
This study suggests that TLE involves altered structural connectivity in a network that reaches beyond the temporal lobe, especially in the default mode network.
From the Athinoula A. Martinos Center for Biomedical Imaging, 149 Thirteenth St, Suite 2301, Charlestown, MA 02129 (M.N.D., L.D., N.T., C.R., S.M.S.); Department of Radiology, Massachusetts General Hospital, Charlestown, Mass (M.N.D., L.D., N.T., S.M.S.); and Department of Neurology, Brigham and Women's Hospital, Boston, Mass (C.R.).
Matthew N
MN
DeSalvo
Linda
L
Douw
Naoaki
N
Tanaka
Claus
C
Reinsberger
Steven M
SM
Stufflebeam
D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001931:Brain Mapping / Q000379:methods*; D016022:Case-Control Studies; D002648:Child; D056324:Diffusion Tensor Imaging; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015225:Magnetoencephalography; D008875:Middle Aged; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D015899:Tomography, Emission-Computed, Single-Photon