Effect of Focal versus Generalized epilepsy on the DTI of Corpus Callosum for Patients with Normal MRI
Abstract number :
2.115
Submission category :
5. Neuro Imaging
Year :
2010
Submission ID :
12709
Source :
www.aesnet.org
Presentation date :
12/3/2010 12:00:00 AM
Published date :
Dec 2, 2010, 06:00 AM
Authors :
Zhimin Li, E. Castillo, M. Gonz lez Nosti, J. Slater, G. Von Allmen, O. Hope and A. Papanicolaou
Rationale: The role of large white matter bundles in generalized and focal seizures is still unknown. Recently, in an animal seizure model, it was demonstrated that diffusion tensor imaging (DTI) can detect localized decreases in fractional anisotropy (FA) in the anterior corpus callosum (CC) for adult epileptic rats compared to control rats (e.g. Chahboune et al). We investigated whether this observation holds in the case of pediatric patients with non-lesional focal and generalized epilepsies. Specifically, we tested the hypothesis that generalized epilepsy would degrade the functional integrity of CC than focal epilepsy would. Methods: DTI data from 17 pediatric and young adult epilepsy patients aged 2- 27 years (6 with generalized and 11 age-matched with focal epilepsy) with normal MRI (according to standard radiological inspection) were collected during their routine presurgical evaluations. Then DTI-derived metrics of FA were calculated for the midsagittal CC, which is divided into segments for each patient as described by Witelson (e.g. Witelson et al). After that, comparison of those metrics between generalized versus focal epilepsy groups were carried out for the CC segments. Results: The FA values for five segments of the CC (ranging from the genu to the splenium) were submitted to a 2(epilepsy groups) by 5 (CC segments) ANOVA which resulted in main effects for both factors and no interaction effect. Specifically, the FA values differed significantly (p<0.001) for the different segments in both groups, with the middle segments having the lowest values. This finding concurs with and replicates previous findings with normal and multiple sclerosis subjects (e.g. Khader et al). Moreover, the FA values of CC in the generalized epilepsy group were significantly lower (p.< 0.002) than those in the focal epilepsy group indicating that generalized epilepsy is more likely to affect the functional integrity of the CC. Conclusions: This study provides initial evidence that generalized epilepsy affects the functional integrity of CC more than focal epilepsy in pediatric and young adult patients. Further study will clarify the pathophysiology of this phenomenon and whether the same effect can be observed for older patients. References: Chahboune H, Mishra AM, DeSalvo MN, Staib LH, Purcaro M, Scheinost D, Papademetris X, Fyson SJ, Lorincz ML, Crunelli V, et al. (2009): DTI abnormalities in anterior corpus callosum of rats with spike-wave epilepsy. Neuroimage 47:459-466. Witelson. S.F. and Goldsmith. C.H.. The relationship of hand preference to anatomy of the corpus callosum in men. Brain Res..545(1991) 175-182. HASAN, K.M., GUPTA, R.K., SANTOS, R.M., WOLINSKY, J.S., and NARAYANA, P.A. (2005). Diffusion tensor fractional anisotropy of the normal-appearing seven segments of the corpus callosum in healthy adults and relapsing-remitting multiple sclerosis patients. J. Magn. Reson. Imaging. 21, 735-743.
Neuroimaging