Voxel-based morphometry in patients with idiopathic generalized epilepsies

University of Campinas, Conceição de Campinas, São Paulo, Brazil
NeuroImage (Impact Factor: 6.36). 09/2006; 32(2):498-502. DOI: 10.1016/j.neuroimage.2006.04.174
Source: PubMed


Idiopathic generalized epilepsies (IGE) are a group of frequent age-related epilepsy syndromes. IGE are clinically characterized by generalized tonic-clonic, myoclonic and absence seizures. According to predominant seizure type and age of onset, IGE are divided in subsyndromes: childhood absence and juvenile absence epilepsy (AE), juvenile myoclonic epilepsy (JME) and generalized tonic-clonic seizures on awakening (GTCS). The limits between these subsyndromes are not well defined, supporting the existence of only one major syndrome. Visual assessment of routine magnetic resonance imaging (MRI) in patients with IGE is normal. MRI voxel-based morphometry (VBM) uses automatically segmented gray and white matter for comparisons, eliminating the investigator bias. We used VBM to study 120 individuals (47 controls, 44 with JME, 24 with AE and 15 with GTCS) to investigate the presence of subtle structural abnormalities in IGE subsyndromes. VBM was performed searching for abnormalities on gray matter concentration (GMC) between patients groups and controls. Compared to controls, JME presented increased GMC in frontobasal region and AE showed increased GMC in the superior mesiofrontal region. The GTCS group did not differ from controls. There were no areas of reduced GMC with the statistical level selected. Region of interest analysis showed increased GMC in the anterior portion of the thalamus in patients with absence seizures. Our results support subtle GMC abnormalities in patients with JME and AE when compared to controls. These findings suggest the existence of different patterns of cortical abnormalities in IGE subsyndromes.

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    • "c o m / l o c a t e / y e b e h Please cite this article as: Lin K, et al, Hippocampal atrophy and memory dysfunction in patients with juvenile myoclonic epilepsy, Epilepsy Behav (2013), allowed for the identification of subtle functional and structural abnormalities , mainly in the thalamus and frontal lobes. While studies using voxel-based morphometry (VBM) have demonstrated reduced gray matter concentration in the thalamus and prefrontal regions and increased concentration in the mesial frontal and frontobasal regions [11] [12] [13] [14], proton magnetic resonance spectroscopy (1H-MRS) has revealed metabolic dysfunction particularly in the thalamus and prefrontal lobes [15] [16] [17] [18]. "
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    ABSTRACT: Juvenile myoclonic epilepsy (JME) is a well-defined idiopathic generalized epilepsy (IGE) syndrome, being the most common IGE in adults and accounting for 5-11% of patients with epilepsy. While neuropsychological and neuroimaging studies have discussed the thalamofrontal dysfunction as the major pathophysiologic mechanism of JME, investigation on memory is scarce in patients with JME, with lack of objective assessments addressing common complaints and daily difficulties such as recalling telephone numbers, messages to pass on, and taking antiepileptic drugs regularly. The aim of this study was to objectively assess memory deficits in a group of patients with JME using neuropsychological examination combined with structural MRI of the hippocampi. After informed consent, a cohort of 56 consecutive patients with JME (29 males; mean age±SD=26.5±9.01years; range=14.0-55.0years) was included. The control group consisted of 42 healthy volunteers (18 males; mean age±SD=31.0±8.54years; range=20.0-56.0years) without a family history of neuropsychiatric disorders. Patients and controls were submitted to a MRI and to a neuropsychological assessment, and comparisons between groups were performed, as well as a correlation study between hippocampal atrophy and neuropsychological performance in a group of patients with JME. The level of statistical significance was set at p<0.05. Significant hippocampal atrophy among patients with JME was observed, which was correlated with memory dysfunctions. The present findings reinforce the existence of functional-anatomic ictogenic networks that are not limited to frontal lobes, providing further support towards the concept of 'system epilepsies' in JME.
    Full-text · Article · Aug 2013 · Epilepsy & Behavior
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    • "The identified alterations in orbitofrontal and mesial frontal cortical thickness support previously described frontal GMV abnormalities (Woermann et al., 1999; Betting et al., 2006), and indicate that such GMV changes are likely explained by an increase in cortical thickness. Holmes et al. (2010) applied dense array scalp electroencephalography (EEG) recordings to study the epileptiform discharges in 10 patients with JME and found all patients to have epileptiform activity originating from the orbitofrontal and medial frontopolar cortices (Holmes et al., 2010). "
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    ABSTRACT: The goal of this study was to characterize cerebral cortex thickness patterns in juvenile myoclonic epilepsy (JME). Surface-based morphometry (SBM) was applied to process brain magnetic resonance images acquired from 24 patients with JME and 40 healthy controls and quantify cerebral cortex thickness. Differences in cortical thickness between patients and controls were determined using generalized linear model (covariates: age and gender). In patients with JME, thickness increase was detected bilaterally within localized regions in the orbitofrontal and mesial frontal cortices. Such thickness patterns coexisted with significant bilateral reduction in thalamic volume. These findings confirm that the underlying mechanisms in JME are related to aberrant corticothalamic structure and indicate that frontal cortex abnormalities are possibly linked to regional increase in cerebral cortical thickness.
    Full-text · Article · Aug 2013 · Epilepsia
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    • "c o m / l o c a t e / y e b e h should also be investigated and considered [29] [30] [31]. Structural abnormalities have been found in the hippocampus, cerebellum, and insular , occipital, and posterior cingulate cortices, suggesting that brain dysfunction in JME extends beyond the thalamofrontal circuitry [17] [23] [29] [30]. Furthermore, most of the altered regions reported in these previous studies are associated with a variety of emotional and behavioral processes and, therefore, can be dysfunctional in patients with JME with cluster B PD [15] [16]. "
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    ABSTRACT: Cluster B personality disorders (PD), characterized as emotional instability, immaturity, lack of discipline, and rapid mood changes, have been observed among patients with juvenile myoclonic epilepsy (JME) and have been associated with a worse seizure outcome. Proper understanding of the neurobiology of PD associated with JME could contribute to understanding the basis for earlier and more effective interventions. In the present study, volumetric and geometric features of cortical structure were assessed through an automated cortical surface reconstruction method aiming to verify possible structural cortical alterations among patients with JME. Twenty-two patients with JME with cluster B PD, 44 patients with JME without psychiatric disorders, and 23 healthy controls were submitted to a psychiatric evaluation through SCID I and SCID II and to an MRI scan. Significant cortical alterations in mesiofrontal and frontobasal regions, as well as in other limbic and paralimbic regions, were observed mainly in patients with JME with PD. The present study adds evidence to the hypothesis of frontal and limbic involvement in the pathophysiology of cluster B PD in JME, regions linked to mood and affective regulation, as well as to impulsivity and social behavior. Moreover, a multidimensional pattern of frontal, limbic, and paralimbic changes was observed through a method of structural analysis which offers different and simultaneous geometric features, allowing the elaboration of important pathophysiologic insights about cluster B PD in JME.
    Full-text · Article · Mar 2013 · Epilepsy & Behavior
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