Amygdala enlargement: Temporal lobe epilepsy subtype or nonspecific finding?

Area of Science:

• Neurology
• Radiology
• Epileptology

Background:

• Amygdala enlargement (AE) is noted in temporal lobe epilepsy (TLE), suggesting it may indicate a distinct TLE subtype.
• The prevalence of AE in other epilepsy syndromes and healthy individuals is not well-established, questioning its utility as a marker for focal epileptogenicity.

Purpose of the Study:

• To investigate the rates of amygdala enlargement (AE) across different epilepsy syndromes and healthy controls.
• To determine if AE is a reliable indicator of focal epileptogenicity in nonlesional localization-related epilepsy (LRE).

Main Methods:

• Quantitative analysis of high-resolution T1-weighted MRI to assess AE rates.
• Comparison of AE prevalence in patients with nonlesional LRE (including TLE and extratemporal epilepsy), idiopathic generalized epilepsy (IGE), and healthy controls (HCs).

Main Results:

• AE was present in all groups, but occurred more frequently in LRE (18.4%) compared to IGE (5.9%) and HCs (6.4%).
• While ipsilateral AE was more common in TLE (19.4%) than extratemporal epilepsy (10.5%), the difference was not statistically significant.
• Among unilateral LRE patients with AE, over half (52%) exhibited bilateral or contralateral AE relative to seizure onset.

Conclusions:

• Amygdala enlargement (AE), when quantified by MRI volumetry, appears to be an associated feature rather than a specific marker for focal seizure onset in nonlesional LRE.
• The findings limit the value of AE as a sole indicator for pinpointing seizure origins in epilepsy.