OBJECTIVE

The seizure network may be different between temporal lobe epilepsy with hippocampal sclerosis (TLE+HS) and without HS (TLE-HS). Chronic seizure activity may alter the diffusion properties of a seizure network. The thalamus is known to have an anatomical connection to the medial temporal area and to play a role in seizure modulation. This study aimed to evaluate differences in thalamic changes between TLE+HS and TLE-HS with diffusion tensor imaging (DTI).

METHODS

Nine patients with TLE+HS and nine patients with TLE-HS were included in the study. All patients underwent surgery with good seizure outcomes. Hippocampal sclerosis was verified pathologically. Sixteen right-handed, normal subjects were enrolled as controls. DTI was acquired using 3.0 T MRI. The mean diffusivity (MD) and fractional anisotropy (FA) were calculated in the center of the bilateral thalamus with the DTIstudio program.

RESULTS

The MD of bilateral thalami increased in both TLE groups compared to controls (p<0.05), while FA values did not differ from controls. The MD of the thalamus ipsilateral to the epileptogenic side was higher in the TLE+HS group than in the TLE-HS group (p=0.007). Onset age, seizure duration, seizure frequency and total seizure number were not correlated with FA and MD changes (p>0.05).

CONCLUSION

Bilateral thalamic diffusion properties are altered in temporal lobe epilepsy. The presence of hippocampal sclerosis enhances the change ipsilaterally.