Thalamic Damage in Temporal Lobe Epilepsy with Mesial Temporal Sclerosis

Kim, Young Dae; Heo, Kyoung; Lee, Seung Koo; Park, Sun Ah; Park, Soo Chul; Chang, Jin Woo; Lee, Byung In

Abstract

PURPOSE: To investigate the frequency of the thalamic damage and its relationship with clinical data in patients with temporal lobe epilepsy and mesial temporal sclerosis (MTS).
METHODS
We evaluated 45 patients with temporal lobe epilepsy showing unequivocal changes of unilateral MTS by the visual inspection of magnetic resonance imaging (MRI) compared to 20 controls. We presumed the inferior margin of the lateral ventricle (IMLV) posterior to the foramen of Monro reflects the volume of the thalamus, and investigated the thalamic damage by comparing bilateral IMLVs on oblique coronal T2 MR images posterior to the foramen of Monro. The relationships between clinical data and the presence of asymmetry of IMLV were evaluated.
RESULTS
None of the control group had asymmetry of the hippocampus or IMLV. Asymmetry of IMLV was observed in 42% (19 of 45) of the patient group;IMLV was downward on the ipsilateral side in 40% (18), and on the contralateral side of MTS in one of the four patients having a larger lateral ventricle on the contralateral side of MTS. An asymmetric small fornix and mamillary body was found in 42% and 29% of the patients, respectively, in all ipsilateral to the side of MTS. A history of status epilepticus (SE) was more frequent in patients with downward IMLV ipsilateral to the side of MTS than in patients with symmetry of IMLV (five of 18 versus one of 26, p=0.011).
CONCLUSIONS
This study suggests that the thalamic damage may be more frequently associated with MTS, when compared with previous studies, which applied more strict methods in evaluating the thalamic damage. There is a significant correlation between the presence of asymmetrical IMLV and history of SE, and our study suggests that excessive and prolonged seizure activity related to SE, can provoke thalamic injury in patients with temporal lobe epilepsy and MTS.