Patterns of Gray Matter Abnormalities in Idiopathic Generalized Epilepsy: A Meta-Analysis of Voxel-Based Morphology Studies

Abstract

ObjectiveWe aimed to identify the consistent regions of gray matter volume (GMV) abnormalities in idiopathic generalized epilepsy (IGE), and to study the difference of GMV abnormalities among IGE subsyndromes by applying activation likelihood estimation (ALE) meta-analysis.MethodsA systematic review of VBM studies on GMV of patients with absence epilepsy (AE), juvenile myoclonic epilepsy (JME), IGE and controls indexed in PubMed and ScienceDirect from January 1999 to June 2016 was conducted. A total of 12 IGE studies, including 7 JME and 3 AE studies, were selected. Meta-analysis was performed on these studies by using the pooled and within-subtypes analysis (www.brainmap.org). Based on the above results, between-subtypes contrast analysis was carried out to detect the abnormal GMV regions common in and unique to each subtype as well.ResultsIGE demonstrated significant GMV increase in right ventral lateral nucleus (VL) and right medial frontal gyrus, and significant GMV decrease in bilateral pulvinar. For JME, significant GMV increase was seen in right medial frontal gyrus, right anterior cingulate cortex (ACC), while significant GMV decrease was found in right pulvinar. In AE, the most significant GMV increase was found in right VL, and slight GMV reduction was seen in right medial dorsal nucleus, right subcallosal gyrus, left caudate and left precuneus. No overlapped and unique regions with significant GMV abnormalities were found between JME and AE.SignificanceThis meta-analysis demonstrated that thalamo-frontal network was a structure with significant GMV abnormality in IGE, and the IGE subsyndromes showed different GMV abnormal regions. These observations may provide instructions on the clinical diagnosis of IGE.

Brain Morphology in Patients with Genetic Generalized Epilepsy: Its Heterogeneity among Subsyndromes

“…For the patients with JME, a significant gray matter volume increase is seen in medial frontal and anterior cingulate cortex, while significant gray matter decrease is found in pulvinar region. For the patients with AE, gray matter increase is found in thalamus, whereas gray matter decrease is revealed in subcallosal cortex, caudate nucleus, and precuneus [10]. However, this study did not investigate surface-based morphometry, such as cortical thickness, surface areas, or volumes in the patients with GGE, but only analyze the results of studies of voxelbased morphometry.…”

“…However, the structural differences in brain morphology among the different GGE syndromes are less well defined [6,8]. Only one study with applying activation likelihood estimation meta-analysis has showed that there are differences of gray matter volumes abnormalities among GGE subsyndromes [10]. For the patients with JME, a significant gray matter volume increase is seen in medial frontal and anterior cingulate cortex, while significant gray matter decrease is found in pulvinar region.…”

“…In addition, studies performed in a voxel-per-voxel basis like voxel-based morphometry require that the images are aligned to a common space has the potential for introducing confoundings, such as misalignment, misclassification, and false detection of normal variants of folding patterns as focal changes of gray matter volumes [11]. Additionally, the previous study did not evaluate the brain morphology in patients with GTC alone [10]. Furthermore, meta-analysis study had several limitations, such as no correlation analysis between the clinical variables and gray matter volume abnormalities, and analysis based on studies with heterogeneous methodology.…”

Besondere bildgebende Befunde bei primär generalisierten Epilepsien

“…Abb. 1a; [1,2,14]) und in Diffusions-Tensor-Bildgebungs(DTI)-Untersuchungen Verände-rungen der thalamokortikalen Verbindungen des Frontallappens [12]. Diese Befunde wurden mittlerweile mehrmals repliziert [2], insbesondere bei der juvenilen myoklonischen Epilepsie (JME), dem häufigsten IGE-Syndrom.…”

Brain morphological abnormalities in genetic generalized epilepsies: The starting point?

“…Although the International League Against Epilepsy recognizes that GGEs characteristically have normal brain magnetic resonance imaging (MRI), studies for >2 decades have reported subtle brain abnormalities detected by quantitative neuroimaging techniques . Quantitative MRI studies in GGEs more often describe thalamic volume reduction in groups of individuals, although there are also descriptions of volume increase of the thalamus or no thalamic abnormality . Likewise, abnormalities of cortical and other subcortical structures vary in different studies .…”