Volume change in amygdala enlargement as a prognostic factor in patients with temporal lobe epilepsy: A longitudinal study

OBJECTIVE Considering the clinical heterogeneity of temporal lobe epilepsy with amygdala enlargement (TLE-AE), identifying distinct prognostic subgroups of TLE-AE has clinical implications. Until now, baseline volume of the enlarged amygdala (EAV) has consistently failed to predict prognosis in TLE-AE. Based on studies suggesting that patients responsive to antiepileptic drugs (AEDs) exhibit remission of AE on follow-up imaging, we investigated whether reduction rate of EAV is predictive of long-term prognosis in TLE-AE. METHODS Sixty-one consecutive patients with two separate magnetic resonance imaging (MRI) scans were enrolled. To utilize longitudinally measured biomarkers in prediction, the period beyond the first MRI acquisition was split into two periods: the "observation window" (period between the two MRIs) and "prediction window" (follow-up period beyond the second MRI). Patients were classified according to their AED responsiveness during the observation window, and AED-responsive patients were further subdivided by initial seizure frequency: (a) AED-responsive patients presenting with low-frequency seizures (