Introduction: Temporal lobe epilepsy with hippocampal sclerosis (TLE-HS) is associated with high rates of drug resistance and widespread structural abnormalities. MRI T2-relaxometry can provide valuable information regarding these structural changes, particularly within the hippocampus.

Objectives: To evaluate whether T2 relaxometry changes progress over time in patients with unilateral (left: L-HS; right: R-HS) and bilateral (Bil-HS) TLE-HS.

Methods: We included 131 patients: 71 L-HS, 49 R-HS, and 11 Bil-HS. All underwent two MRI scans with at least a 1-year interval, including high-resolution 3D T1-weighted and T2 multiecho sequences. T2 maps were quantified using single exponential fit, coregistered, normalized to MNI space, and labeled via the Desikan atlas. Longitudinal differences in the thalami, amygdalae, and hippocampi were analyzed using paired t-tests.

Results: The mean age was 46.21 years. The mean interval between MRIs was 6.4 years (LHS), 6.17 years (R-HS), and 7.88 years (Bil-HS). R-HS patients showed a significant T2 signal increase in the contralateral and ipsilateral thalamus (p = 0.0001; p < 0.0001) and hippocampus (p = 0.0004; p < 0.0001). L-HS patients exhibited significant increases in the ipsiand contralateral thalamus (p < 0.0001; p < 0.0001), hippocampus (p < 0.0001; p < 0.0001), and amygdala (p = 0.0002; p = 0.0158). Bil-HS patients showed T2 increases in the left (p = 0.0180) and right (p = 0.0445) hippocampi, with no significant changes in the thalamus or amygdala.

Conclusions: T2-signal changes progress over time in both hippocampi of TLE-HS patients, regardless of laterality. Additionally, longitudinal changes extend to both thalami in unilateral patients, and specifically to both amygdalae in the L-HS group. Whether these changes reflect gliosis, axonal, or neuronal damage remains to be confirmed

Fernando Cassol is a sixth-year Medical Student in University of Campinas (UNICAMP) in Brazil.