White-matter diffusion abnormalities in temporal-lobe epilepsy with and without mesial temporal sclerosis

Area of Science:

• Neuroscience
• Neurology
• Medical Imaging

Background:

• Epilepsy, a neurological disorder, is often viewed as a grey matter issue, but white matter connectivity changes significantly impact seizure activity.
• Previous studies identified white matter abnormalities in temporal-lobe epilepsy (TLE) patients with mesial temporal sclerosis (MTS).
• Patients with TLE but without MTS exhibit distinct disease progression and surgical outcomes compared to those with MTS.

Purpose of the Study:

• To investigate whether white matter abnormalities in TLE are associated with the presence of MTS.
• To determine if these abnormalities also occur in non-lesional TLE (nl-TLE).

Main Methods:

• Diffusion tensor imaging (DTI) was employed to examine white matter tract integrity.
• The study included 17 patients with TLE and MTS (TLE+uMTS), 13 patients with nl-TLE, and 25 healthy controls.
• Specific tracts analyzed included the fornix, cingulum, external capsules, and corpus callosum.

Main Results:

• Abnormalities in the fornix were observed exclusively in patients with MTS.
• While both TLE groups showed increased cingulum diffusivity, decreased anisotropy was specific to the TLE+uMTS group.
• Reduced anisotropy in the corpus callosum (frontal and temporal components) and external capsules was present in TLE patients irrespective of MTS.

Conclusions:

• Certain white matter bundles are similarly affected in both TLE subtypes.
• Abnormalities in the fornix and cingulum, tracts connected to mesial temporal structures, appear to be characteristic of TLE with MTS.