Progressing the White Matter Alteration Associated with Surgery on Right Temporal Lobe Epilepsy Patients:A Longitudinal Diffusion Tensor Imaging Study

Objective To investigate the alteration of white matter in right temporal lobe epilepsy(TLE) patients with unilateral hippocampus sclerosis(HS) after surgery and assess the relationship between these alterations and the clinical variables. Methods Ten right TLE patients who underwent right anterior temporal lobectomy or selective amygdalohippocampectomy were recruited between July 2008 and August 2009. Diffusion tensor imaging(DTI) was performed before surgery, and 4.5-month follow-up was done using a gradient-echo echo-planar imaging(EPI) sequence on a 3 T MR imaging system(EXCITE, General Electric, Milwaukee, USA). The fractional anisotropy(FA) was calculated using DtiStudio software. Voxel based analysis of the FA maps between baseline and 4.5 months after surgery was performed with paired t test by using the SPM8. Pearson correlation coefficients were calculated to evaluate the relationship between some clinical variables(duration, frequency and interval days of scanning) and the mean values of FA. The significance levels were set at P 0.05(two-tailed). Results The FA values significantly reduced in the left inferior temporal gyrus, bilateral middle frontal gyrus and left putamen. The increased FA areas included the left parahippocampal gyrus, left temporal lobe, and right inferior frontal gyrus. There was a correlation between the changes of FA values of right inferior frontal gyrus and age of onset, and the left inferior temporal gyrus correlated with the postoperative follow-up interval. Conclusions The affected white matter after surgery is not restricted to the temporal lobe. It also involves the extratemporal structure. The present study provides the neuroimaging evidence of white matter alteration pattern in right TLE patients.