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. 2017 May:132:34-40.
doi: 10.1016/j.eplepsyres.2017.02.019. Epub 2017 Mar 2.

Amygdala enlargement: Temporal lobe epilepsy subtype or nonspecific finding?

Anny Reyes  1 , Thomas Thesen  2 , Ruben Kuzniecky  3 , Orrin Devinsky  3 , Carrie R McDonald  4 , Graeme D Jackson  5 , David N Vaughan  6 , Karen Blackmon  7
Affiliations

Amygdala enlargement: Temporal lobe epilepsy subtype or nonspecific finding?

Anny Reyes et al. Epilepsy Res. 2017 May.

Abstract

Objective: Amygdala enlargement (AE) is observed in patients with temporal lobe epilepsy (TLE), which has led to the suggestion that it represents a distinct TLE subtype; however, it is unclear whether AE is found at similar rates in other epilepsy syndromes or in healthy controls, which would limit its value as a marker for focal epileptogenicity.

Methods: We compared rates of AE, defined quantitatively from high-resolution T1-weighted MRI, in a large multi-site sample of 136 patients with nonlesional localization related epilepsy (LRE), including TLE and extratemporal (exTLE) focal epilepsy, 34 patients with idiopathic generalized epilepsy (IGE), and 233 healthy controls (HCs).

Results: AE was found in all groups including HCs; however, the rate of AE was higher in LRE (18.4%) than in IGE (5.9%) and HCs (6.4%). Patients with unilateral LRE were further evaluated to compare rates of concordant ipsilateral AE in TLE and exTLE, with the hypothesis that rates of ipsilateral AE would be higher in TLE. Although ipsilateral AE was higher in TLE (19.4%) than exTLE (10.5%), this difference was not significant. Furthermore, among the 25 patients with unilateral LRE and AE, 13 (52%) had either bilateral AE or AE contralateral to seizure onset.

Conclusion: Results suggest that AE, as defined with MRI volumetry, may represent an associated feature of nonlesional localization related epilepsy with limited seizure onset localization value.

Keywords: MRI; Morphometry; Nonlesional epilepsy; Temporal lobe epilepsy.

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Figures

Figure 1
Figure 1
Kernel density plots for amygdala volume z-scores in the LRE, IGE, and HC groups. The estimate of the probability density function is plotted against (A) left and (B) right amygdala volume z-scores. The dotted line represents the z-score cutoff for amygdala enlargement (z > 2). (A) The left amygdala distribution across groups shows a larger percentage of individuals with amygdala enlargement in the LRE group (12%) relative to the IGE (6%) and HC (4%) groups. (B) Similarly, there were a greater percentage of individuals with right amygdala enlargement in the LRE group (14%) relative to the IGE (3%) and HC group (3%). LRE=Localization Related Epilepsy; IGE=Idiopathic Generalized Epilepsy; HC=Healthy Controls.
Figure 2
Figure 2
Kernel density plots for amygdala volume z-scores in the TLE and exTLE groups. The estimate of the probability density function is plotted against (A) ipsilateral and (B) contralateral amygdala volume z-scores. The dotted line represents z-score cutoff for amygdala enlargement. (A) The ipsilateral amygdala distribution across groups shows a higher percentage of individuals with amygdala enlargement in the TLE group (19%) relative to the exTLE (11%) group, although this difference was not significant. (B) There was no difference in the percentage of individuals with contralateral amygdala enlargement between the TLE group (10%) and exTLE (11%) groups. TLE=Temporal Lobe Epilepsy; exTLE= Extratemporal Lobe Epilepsy.
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