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Journal of Epilepsy and Clinical Neurophysiology

Print version ISSN 1676-2649

Abstract

YASUDA, Clarissa Lin et al. Recovery of white matter atrophy after epilepsy surgery: structural evidences through voxel-based morphometry. J. epilepsy clin. neurophysiol. [online]. 2009, vol.15, n.1, pp. 07-11. ISSN 1676-2649.  http://dx.doi.org/10.1590/S1676-26492009000100003.

OBJECTIVES: To study pre and postoperative WMA in MTLE patients. METHODS: We performed Voxel-Based Morphometry (VBM) with volume of interest (VOI) in 69 controls (mean age, 34.3±11.1 years) and 67 operated patients (mean age, 34.1±10.4 years) with unilateral MTLE. 34 became seizure-free (SzFree-Group), 23 improved (Engel IB-IIA [Partial recovery-group]) and 10 did not improve (Engel III-IV [Failure-Group]). All had pre and postoperative MRIs (one year minimum). We flipped MRIs of right MTLE patients in order to avoid right-to-left analysis cancelation. VBM was performed on SPM2/MATLAB7.0 with individual masks for surgical lacunae and 1% false-discovery-rate to control for multiple comparisons. We used MARSbar <www.marsbar.sourceforge.net> routine to select ROIs and t-test for statistical analyses. RESULTS: Mean postoperative follow-up was 60.2 (±SD 30.7) months. On baseline MRI, SzFree-Group showed White Matter Atrophy (WMA) involving temporal lobes [TL], ipsilateral occipital, parietal and frontal regions, with areas of significant recovery of WMA on postoperative MRI. Partial recovery-Group presented a more restricted pattern of WMA, involving ipsilateral temporal lobe, contralateral superior temporal gyrus and few areas in bilateral cingulated and orbitofrontal areas. In this group we also identified areas with relative increase of WM after surgery. By contrast, Failure-Group showed more widespread bi-hemispheric areas of WMA on baseline MRI without postoperative improvement. CONCLUSIONS: Although we have identified some differences in baseline WMA, we were unable to correlate a more widespread pattern with a worse prognosis, as SzFree-Group, also presented a bilateral distribution of WMA. The recovery of WMA in SzFree-Group and Partial recovery-group is in agreement with previous MRS and PET studies and suggests that a network of neuronal dysfunction in MTLE can be, at least in part, reversible after successful postoperative seizure control.

Keywords : Temporal lobe epilepsy; white matter; surgery; VBM; plasticity.

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