Investigation of volume changes in mesolimbic structures in patients with mesial temporal sclerosis

Objective: Temporal lobe epilepsy (TLE) is the most common of the localization-related epilepsies. The condition in which TLE is accompanied by hippocampal sclerosis is known as mesial temporal sclerosis (MTS). MTS is the most common lesion in drug-resistant TLE patients. In MTS, atrophy is seen in structures such as the hippocampus and amygdala. However, it is thought that MTS may affect all limbic system structures. Therefore, in our study, we aimed to examine the volume changes in the mesolimbic system structures of patients with MTS and compare them with healthy controls. Method: A total of 36 MTS patients, 17 right MTS and 19 left MTS patients, and 36 healthy individuals compatible with the patient group in terms of age and gender were retrospectively screened and included in our study. Subcortical, gray matter and white matter volumes and cortical thicknesses of the mesolimbic structures of individuals in all groups were measured and compared with FreeSurfer software. Results: Subcortical, white matter and gray matter volume measurements of the mesolimbic structures of right MTS and left MTS patients were statistically significantly decreased compared to the control group (p<0.05). No significant difference in cortical thickness was seen. The mean cortical thickness in the patient group was higher than in the control group. While a more widespread and bilateral atrophy pattern was observed in left MTS patients, the atrophy pattern was observed mostly in the ipsilateral hemisphere in right MTS patients. Conclusion: In MTS, atrophy is observed in the hippocampus and adjacent limbic system structures. This atrophy pattern was more evident in subcortical structures and white matter. Our findings show that the hippocampus, which is known to be affected in MTS, and its connections with other cortical limbic structures are affected first. We think that the higher average cortical thickness in the patient group may be related to the effect of clinical parameters on mesolimbic structures.