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. 2010 Apr;51(4):519-28.
doi: 10.1111/j.1528-1167.2009.02506.x. Epub 2010 Feb 12.

Extrahippocampal gray matter loss and hippocampal deafferentation in patients with temporal lobe epilepsy

Leonardo Bonilha  1 , Jonathan C Edwards, Stephen L Kinsman, Paul S Morgan, Julius Fridriksson, Chris Rorden, Zoran Rumboldt, Donna R Roberts, Mark A Eckert, Jonathan J Halford
Affiliations

Extrahippocampal gray matter loss and hippocampal deafferentation in patients with temporal lobe epilepsy

Leonardo Bonilha et al. Epilepsia. 2010 Apr.

Abstract

Purpose: Medial temporal epilepsy (MTLE) is associated with extrahippocampal brain atrophy. The mechanisms underlying brain damage in MTLE are unknown. Seizures may lead to neuronal damage, but another possible explanation is deafferentation from loss of hippocampal connections. This study aimed to investigate the relationship between hippocampal deafferentation and brain atrophy in MTLE.

Methods: Three different MRI studies were performed involving 23 patients with unilateral MTLE (8 left and 15 right) and 34 healthy controls: (1) voxel-based morphometry (VBM), (2) diffusion tensor imaging (DTI) and (3) probabilistic tractography (PT). VBM was employed to define differences in regional gray matter volume (GMV) between controls and patients. Voxel-wise analyses of DTI evaluated differences in fractional anisotropy (FA), mean diffusivity (MD) and hippocampal PT. Z-scores were computed for regions-of-interest (ROI) GMV and peri-hippocampal FA and MD (to quantify hippocampal fiber integrity). The relationship between hippocampal deafferentation and regional GMV was investigated through the association between ROI Z scores and hippocampal fiber integrity.

Results: Patients with MTLE exhibited a significant reduction in GMV and FA in perihippocampal and limbic areas. There was a decrease in hippocampal PT in patients with MTLE in limbic areas. A significant relationship between loss of hippocampal connections and regional GMV atrophy was found involving the putamen, pallidum, middle and inferior temporal areas, amygdala and ceberellar hemisphere.

Discussion: There is a relationship between hippocampal disconnection and regional brain atrophy in MTLE. These results indicate that hippocampal deafferentation plays a contributory role in extrahippocampal brain damage in MTLE.

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Conflict of interest statement

Disclosure: The authors report no financial or non-financial conflicts of interest associated with this study.

Figures

Figure 1
Figure 1
The upper panel shows the tridimensional representation of fibers from the hippocampus in one representative healthy subject (A), the middle panel (B) shows the location of the probabilistic tractography of fibers from the hippocampus on average amongst healthy subjects (the scale bars represent the number of fibers) and the lower panel (C) shows the perihippocampal masks with 95% of chance of encompassing all fibers traveling from the hippocampus.
Figure 2
Figure 2
The location of FA reduction and MD increase in patients with left and right MTLE. The scale bars represent Z-scores.
Figure 3
Figure 3
The location of significantly reduced hippocampal probabilistic tractography in patients compared with controls (red rectangles highlight the significant areas, above a critical threshold for repeated measures correction, Z = 3.1, left side and Z = 2.9, right side). The images are displayed in neurological convention, i.e., the left side represents the left side of the brain. The scale bars demonstrate the Z-scores.
See this image and copyright information in PMC

References

    1. Alessio A, Bonilha L, Rorden C, Kobayashi E, Min LL, Damasceno BP, Cendes F. Memory and language impairments and their relationships to hippocampal and perirhinal cortex damage in patients with medial temporal lobe epilepsy. Epilepsy Behav. 2006;8:593–600. - PubMed
    1. Andermann F. Why study mesial temporal atrophy in patients with intractable temporal lobe epilepsy? J Neurol Neurosurg Psychiatry. 2003;74:1606–1607. - PMC - PubMed
    1. Ashburner J, Friston KJ. Unified segmentation. Neuroimage. 2005;26:839–851. - PubMed
    1. Bernasconi N, Bernasconi A, Caramanos Z, Antel SB, Andermann F, Arnold DL. Mesial temporal damage in temporal lobe epilepsy: a volumetric MRI study of the hippocampus, amygdala and parahippocampal region. Brain. 2003;126:462–469. - PubMed
    1. Bernasconi N, Duchesne S, Janke A, Lerch J, Collins DL, Bernasconi A. Whole-brain voxel-based statistical analysis of gray matter and white matter in temporal lobe epilepsy. Neuroimage. 2004;23:717–723. - PubMed

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