Abstracts

Rationale: 30-40% of patients with mesial temporal lobe epilepsy (MTLE)experience postoperative seizures.Morphometric analyses on amygdala or hippocampus havestudied to determine factors for postoperative seizures. Recently, the basal ganglia (BG) and thalamus are revealed to be responsible for TLE seizures. We aimed to explore the preoperative morphological changes of BG and thalamus in the contribution of persistent seizures after surgery. Methods: We enrolled brain MRIs of 229 patients (130 with left and 99 with right unilateral MTLE) who underwent unilateral temporal lobectomy and amygdalo-hippocampectomy and of 132 normal controls. All patients had unilateral hippocampal sclerosis on initial MRIs. Postoperative seizure outcome was assessed every year after two years of surgery. Engle Classification 1A was defined as good outcome. A shape analysis of the BG and thalamus was performed using a boundary surface-based method. Covariates were age, gender, and intracranial volume. Shapes of subcortical structures were compared between patients with good (IA) and poor outcomes, and between patients with normal controls. Results: Mean postoperative follow-up period was 4.7 y(range 2-10 y). Left TLE was 4.8 y(n= 130) and right TLE was 4.6 y(n=99).124 (54.8%) patients showed good surgical outcome (class IA), while 105 (45.2%) had poor outcome (class IB-ID, n=18; class II, n=29, class III, n=41, class IV, n=17). Compared to controls, left MTLE patients had significant atrophy of both putamen and left caudate nucleus, and right showed in both putamen and right caudate nucleus. There was no significant regional atrophy in the BG and thalamus between patients with good and poor outcome. The patients with poor outcome had specific regional atrophy in the both amygdala compared to controls. Demographics did not show significant correlations with subcortical volumes of MTLE. Conclusions: Regional atrophy of the BG and thalamus before surgery was significant inunilateral MTLE patients. Putamen was atrophied bilaterally in all patients. However, caudate nucleus ipsilateral to epileptic foci was significantly smaller in left or right MTLE. It suggests the active involvement of putamen and caudate nucleus in the propagation of seizures. Regional atrophy of the BG and thalamus was not associated with postoperative outcome. Funding: None