Amygdala enlargement occurs in patients with mesial temporal lobe epilepsy and hippocampal sclerosis with early epilepsy onset

• Volumetric analysis of mesial structures in patients with MTLE with HS revealed significant amygdala enlargement in 14% of the cases.
• The increased amygdala volume was more often contralateral to the epileptogenic zone.
• Patients with MTLE with HS and enlarged amygdala had significantly earlier epilepsy onset.

Mesial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis (HS) is considered an electroclinical syndrome, and there is a debate whether it is a unique disease or an entity with distinct subtypes. Together with other mesial temporal structures, the amygdala is important in the epileptogenic network of patients with MTLE with HS. During automatic volumetric analysis of mesial structures in a group of 102 patients with MTLE with MRI signs of HS, we observed significant amygdala enlargement in 14 (14%) individuals compared to a group of 79 healthy subjects. The increased amygdala volume was contralateral to the epileptogenic zone and MRI signs of HS in 93% of these patients. Patients with MTLE with HS and enlarged amygdala had significantly earlier epilepsy onset than those without an increase of amygdala volumes. Mesial temporal lobe epilepsy with HS and enlarged amygdala may be a part of the spectrum of this condition.