Focal structural changes and cognitive dysfunction in juvenile myoclonic epilepsy - PubMed (original) (raw)

Focal structural changes and cognitive dysfunction in juvenile myoclonic epilepsy

J O'Muircheartaigh et al. Neurology. 2011.

Abstract

Objective: The aim of this study was to determine if there were focal cortical abnormalities in juvenile myoclonic epilepsy (JME) using neuropsychological investigations and MRI.

Methods: Twenty-eight patients with JME and a large sample of healthy controls were assessed using a series of neuropsychological tests as well as structural and diffusion tensor MRI (DTI). DTI measures assessed fractional anisotropy (FA) within a white matter skeleton.

Results: Neuropsychological testing indicated subtle dysfunctions in verbal fluency, comprehension, and expression, as well as nonverbal memory and mental flexibility. Utilizing whole-brain voxel-based morphometry for gray matter MRI data and tract-based spatial statistics for white matter diffusion MRI data, we found reductions in gray matter volume (GMV) in the supplementary motor area and posterior cingulate cortex and reductions in FA in underlying white matter of the corpus callosum. Supplementary motor area FA predicted scores in word naming tasks and expression scores. Posterior cingulate cortex GMV and FA predicted cognitive inhibition scores on the mental flexibility task.

Conclusions: The neuropsychological, structural, and tractography results implicate mesial frontal cortex, especially the supplementary motor area, and posterior cingulate cortex in JME.

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Figures

Figure 1

Figure 1. Mean normalized gray matter and fractional anisotropy (FA) images

FA skeleton on which the statistical analysis was carried out, overlaid on the FA map taken from the average of all subjects (top row). Average gray matter map of all subjects after normalization and smoothing (bottom row).

Figure 2

Figure 2. Results of the voxelwise analyses

Results from fractional anisotropy (FA) tract-based spatial statistics and gray matter voxel-based morphometry (VBM) analyses overlaid on mean images. Gray matter VBM results show relative gray matter volume decreases in the juvenile myoclonic epilepsy group in the supplementary motor area and posterior cingulate region (A). Reduced FA is reduced in associated regions of the corpus callosum (B). Statistics overlaid on average images are shown at the bottom of each panel.

Figure 3

Figure 3. Probabilistic tractography of the anterior and posterior regions of change

Probabilistic tractography group maps (healthy controls and patients with juvenile myoclonic epilepsy) seeded from posterior (A, orange box) and anterior (B, blue box) corpus callosal regions identified in tract-based spatial statistics analysis. (B) Connectivity from the posterior callosal region; projections include the temporo-parietal projections of the cingulum and splenial fibers. (C) Group average connectivity to anterior superior frontal regions from the anterior callosum.

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