Group‐specific regional white matter abnormality revealed in diffusion tensor imaging of medial temporal lobe epilepsy without hippocampal sclerosis

Abstract

SUMMARYPurpose: In comparison to temporal lobe epilepsy (TLE) patients with hippocampal sclerosis (TLE-HS), TLE patients without HS (TLE-NH) have a similar clinical course but may result in worse surgical outcome. We investigated whether the clinical features related to the lack of HS in TLE patients (TLE-NH) can be explained by water diffusion abnormalities throughout diffusion tensor imaging (DTI) by voxel-based analysis. Methods: Nineteen patients with TLE-HS (left/right TLE 12:7), 18 patients with TLE-NH (left/right TLE 10:8), and 20 controls were included in the study. By statistical parametric mapping (SPM2), the diffusion properties specific to disease characteristics (TLE-HS vs. TLE-NH) were analyzed. Results: In TLE-HS, we found the areas of increased mean diffusivity (MD) in their ipsilateral temporal and extratemporal areas including the hippocampus, parahippocampal, and frontoparietal regions. Left TLE-HS showed a characteristic MD increase in the ipsilateral posterior cingulum, isthmus of corpus callosum, and contralateral occipital and temporal regions, which was not observed in right TLE-HS group. In left TLE-NH, two regions of increased MD were observed in the ipsilateral posterior fornix (within fusiform gyrus) and posterior cingulum. Right TLE-NH did not show any increased MD. Discussion: In left TLE-NH, we could find the water diffusion change along the posterior cingulum, which was quite different from the extensive abnormality from TLE-HS. In addition, there was a lesion-side-specific distribution (left predominant) of pathology in mesial TLE. This provides a possibility that TLE-NH is a heterogenous or entity different from TLE-HS.

Quantitative relaxometry and diffusion MRI for lateralization in MTS and non-MTS temporal lobe epilepsy

“…Asymmetry in DTI findings was also found in other recent studies (Shon et al, 2010, Kemmotsu et al, 2011, Keller et al, 2012, with both MTS and non-MTS patients with left seizure onset having more significant and more widespread abnormalities, including atrophy, than right-onset patients.…”

“…This is in concordance with our findings that lateralization using the neocortical ROI was stronger than the mesial ROI. Shon et al (2010) performed voxel-based analysis of FA and MD and found only one region of increased diffusivity, reported to be in the parahippocampal cingulate. Concha et al (2009) performed tractography of specific white matter structures and found that non-MTS subjects did not have significant diffusion differences in the limbic structures (fornix, cingulum), but abnormalities common to MTS patients were found in the external capsule and corpus callosum.…”

Microstructural brain abnormalities of children of idiopathic generalized epilepsy with generalized tonic‐clonic seizure: A voxel‐based diffusional kurtosis imaging study

“…This was in accordance with the previous findings by DTI in children or adults with epilepsy and GTCS. For example, VBA showed higher MD in the epileptic hippocampus (23,24), the temporal lobes (24)(25)(26), and the parahippocampal and frontoparietal regions (25). In our study the increased MD was mainly due to the extent of increase of l // , and in only several regions the increased l ?…”

Bilateral white matter abnormality in children with frontal lobe epilepsy

“…DTI studies in patients with TLE have demonstrated differences in abnormal DTI in patients with right and left TLE. Shon et al (Shon et al, 2010) found patients with left TLE and hippocampal sclerosis showed increased MD in the ipsilateral posterior cingulum, corpus callosum and contralateral occipital and temporal lobes that were not seen in those with right TLE and hippocampal sclerosis. Similarly, increased MD was noted in the ipsilateral posterior fornix and cingulum in patients with left TLE without hippocampal sclerosis, but not in patients with right TLE.…”