Clinical course of epilepsy and white matter abnormality linked to a novel DYRK1A variant.
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ABSTRACT:
SUBMITTER: Okazaki T
PROVIDER: S-EPMC8275604 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Metachromatic leukodystrophy (MLD) is a rare metabolic disorder leading to demyelination and rapid neurologic deterioration. As therapeutic options evolve, it seems essential to understand and quantify progression of the natural disease. The aim of this study was to assess cerebral volumetric changes in children with MLD in comparison to normal controls and in relation to disease course.Eighteen patients with late-infantile MLD and 42 typically developing children in the same age range (20-59 months) were analyzed in a cross-sectional study. Patients underwent detailed genetic, biochemical, electrophysiologic, and clinical characterization. Cerebral gray matter (GM) and white matter (WM) volumes were assessed by multispectral segmentation of T1- and T2-weighted MRI. In addition, the demyelinated WM (demyelination load) was automatically quantified in T2-weighted images of the patients, and analyzed in relation to the clinical course.WM volumes of patients did not differ from controls, although their growth curves were slightly different. GM volumes of patients, however, were on average 10.7% (confidence interval 6.0%-14.9%, p < 0.001) below those of normally developing children. The demyelination load (corrected for total WM volume) increased with disease duration (p < 0.003) and motor deterioration (p < 0.001).GM volume in patients with MLD is reduced when compared with healthy controls, already at young age. This supports the notion that, beside demyelination, neuronal dysfunction caused by neuronal storage plays an additional role in the disease process. The demyelination load may be a useful noninvasive imaging marker for disease progression and may serve as reference for therapeutic intervention.
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Project description:Increasing evidence suggests that abnormal white matter is central to the pathophysiology and, potentially, the pathogenesis of schizophrenia (SCZ). The spatial distribution of observed abnormalities and the type of white matter involved remain to be elucidated. Seventeen chronically ill individuals with SCZ and 17 age- and gender-matched controls were studied using a 3T magnetic resonance imaging diffusion tensor imaging protocol designed to examine the abnormalities of white matter by region and by level of architectural infrastructure as assessed by fractional anisotropy (FA) in native space. After assessing whole-brain FA, FA was divided into quartiles, capturing all brain regions with FA values from 0 to 0.25, 0.25 to 0.5, 0.5 to 0.75, and 0.75 to 1.0. Mean whole-brain FA was 4.6% smaller in the SCZ group than in healthy controls. This difference was largely accounted for by FA values from the second quartile (between 0.25 and 0.5). Second quartile FA was decreased in all 130 brain regions of the template in the SCZ group, with the difference reaching statistical significance in 41 regions. Correspondingly, the amount of brain tissue with an FA of ?0.4 was significantly reduced in the SCZ group, while the amount of brain tissue falling in the lowest quartile of FA was increased. These findings strongly imply a diffuse loss of white matter integrity in SCZ. Our finding that the loss of integrity disproportionately involves white matter of low to moderate organization suggests an approach to the specificity of white matter abnormalities in SCZ based on microstructure rather than spatial distribution.
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Project description:Previous studies investigating associations between white matter alterations and duration of temporal lobe epilepsy (TLE) have shown differing results, and were typically limited to univariate analyses of tracts in isolation. In this study, we apply a multivariate measure (the Mahalanobis distance), which captures the distinct ways white matter may differ in individual patients, and relate this to epilepsy duration. Diffusion MRI, from a cohort of 94 subjects (28 healthy controls, 33 left-TLE and 33 right-TLE), was used to assess the association between tract fractional anisotropy (FA) and epilepsy duration. Using ten white matter tracts, we analysed associations using the traditional univariate analysis (z-scores) and a complementary multivariate approach (Mahalanobis distance), incorporating multiple white matter tracts into a single unified analysis. For patients with right-TLE, FA was not significantly associated with epilepsy duration for any tract studied in isolation. For patients with left-TLE, the FA of two limbic tracts (ipsilateral fornix, contralateral cingulum gyrus) were significantly negatively associated with epilepsy duration (Bonferonni corrected p < .05). Using a multivariate approach we found significant ipsilateral positive associations with duration in both left, and right-TLE cohorts (left-TLE: Spearman's ρ = 0.487, right-TLE: Spearman's ρ = 0.422). Extrapolating our multivariate results to duration equals zero (i.e., at onset) we found no significant difference between patients and controls. Associations using the multivariate approach were more robust than univariate methods. The multivariate Mahalanobis distance measure provides non-overlapping and more robust results than traditional univariate analyses. Future studies should consider adopting both frameworks into their analysis in order to ascertain a more complete understanding of epilepsy progression, regardless of laterality.
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Project description:Objective: We identified a novel de novo SCN2A variant (M1879T) associated with infantile-onset epilepsy that responded dramatically to sodium channel blocker antiepileptic drugs. We analyzed the functional and pharmacological consequences of this variant to establish pathogenicity, and to correlate genotype with phenotype and clinical drug response.Methods: The clinical and genetic features of an infant boy with epilepsy are presented. We investigated the effect of the variant using heterologously expressed recombinant human NaV 1.2 channels. We performed whole-cell patch clamp recording to determine the functional consequences and response to carbamazepine.Results: The M1879T variant caused disturbances in channel inactivation including substantially depolarized voltage dependence of inactivation, slower time course of inactivation, and enhanced resurgent current that collectively represent a gain-of-function. Carbamazepine partially normalized the voltage dependence of inactivation and produced use-dependent block of the variant channel at high pulsing frequencies. Carbamazepine also suppresses resurgent current conducted by M1879T channels, but this effect was explained primarily by reducing the peak transient current. Molecular modeling suggests that the M1879T variant disrupts contacts with nearby residues in the C-terminal domain of the channel.Interpretation: Our study demonstrates the value of conducting functional analyses of SCN2A variants of unknown significance to establish pathogenicity and genotype-phenotype correlations. We also show concordance of in vitro pharmacology using heterologous cells with the drug response observed clinically in a case of SCN2A-associated epilepsy.
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Project description:The epilepsies are commonly accompanied by widespread abnormalities in cerebral white matter. ENIGMA-Epilepsy is a large quantitative brain imaging consortium, aggregating data to investigate patterns of neuroimaging abnormalities in common epilepsy syndromes, including temporal lobe epilepsy, extratemporal epilepsy, and genetic generalized epilepsy. Our goal was to rank the most robust white matter microstructural differences across and within syndromes in a multicentre sample of adult epilepsy patients. Diffusion-weighted MRI data were analysed from 1069 healthy controls and 1249 patients: temporal lobe epilepsy with hippocampal sclerosis (n = 599), temporal lobe epilepsy with normal MRI (n = 275), genetic generalized epilepsy (n = 182) and non-lesional extratemporal epilepsy (n = 193). A harmonized protocol using tract-based spatial statistics was used to derive skeletonized maps of fractional anisotropy and mean diffusivity for each participant, and fibre tracts were segmented using a diffusion MRI atlas. Data were harmonized to correct for scanner-specific variations in diffusion measures using a batch-effect correction tool (ComBat). Analyses of covariance, adjusting for age and sex, examined differences between each epilepsy syndrome and controls for each white matter tract (Bonferroni corrected at P < 0.001). Across 'all epilepsies' lower fractional anisotropy was observed in most fibre tracts with small to medium effect sizes, especially in the corpus callosum, cingulum and external capsule. There were also less robust increases in mean diffusivity. Syndrome-specific fractional anisotropy and mean diffusivity differences were most pronounced in patients with hippocampal sclerosis in the ipsilateral parahippocampal cingulum and external capsule, with smaller effects across most other tracts. Individuals with temporal lobe epilepsy and normal MRI showed a similar pattern of greater ipsilateral than contralateral abnormalities, but less marked than those in patients with hippocampal sclerosis. Patients with generalized and extratemporal epilepsies had pronounced reductions in fractional anisotropy in the corpus callosum, corona radiata and external capsule, and increased mean diffusivity of the anterior corona radiata. Earlier age of seizure onset and longer disease duration were associated with a greater extent of diffusion abnormalities in patients with hippocampal sclerosis. We demonstrate microstructural abnormalities across major association, commissural, and projection fibres in a large multicentre study of epilepsy. Overall, patients with epilepsy showed white matter abnormalities in the corpus callosum, cingulum and external capsule, with differing severity across epilepsy syndromes. These data further define the spectrum of white matter abnormalities in common epilepsy syndromes, yielding more detailed insights into pathological substrates that may explain cognitive and psychiatric co-morbidities and be used to guide biomarker studies of treatment outcomes and/or genetic research.
| S-EPMC7567169 | biostudies-literature
Project description:Our objective was to evaluate the independent prognostic value of a novel MRI biomarker-objectively diagnosed diffuse white matter abnormality volume (DWMA; diffuse excessive high signal intensity)-for prediction of motor outcomes in very preterm infants. We prospectively enrolled a geographically-based cohort of very preterm infants without severe brain injury and born before 32 weeks gestational age. Structural brain MRI was obtained at term-equivalent age and DWMA volume was objectively quantified using a published validated algorithm. These results were compared with visually classified DWMA. We used multivariable linear regression to assess the value of DWMA volume, independent of known predictors, to predict motor development as assessed using the Bayley Scales of Infant & Toddler Development, Third Edition at 3 years of age. The mean (SD) gestational age of the cohort was 28.3 (2.4) weeks. In multivariable analyses, controlling for gestational age, sex, and abnormality on structural MRI, DWMA volume was an independent prognostic biomarker of Bayley Motor scores ([Formula: see text]= -12.59 [95% CI -18.70, -6.48] R2?=?0.41). Conversely, visually classified DWMA was not predictive of motor development. In conclusion, objectively quantified DWMA is an independent prognostic biomarker of long-term motor development in very preterm infants and warrants further study.
| S-EPMC7523012 | biostudies-literature
Project description:Between 50 and 80% of very preterm infants (<32 weeks gestational age) exhibit increased white matter signal intensity on T2-weighted MRI at term-equivalent age, known as diffuse white matter abnormality (DWMA). A few studies have linked DWMA with microstructural abnormalities, but the exact relationship remains poorly understood. We related DWMA extent to graph theory measures of network efficiency at term in a representative cohort of 343 very preterm infants. We performed anatomic and diffusion MRI at term and quantified DWMA volume with our novel, semi-automated algorithm. From diffusion-weighted structural connectomes, we calculated the graph theory metrics local efficiency and clustering coefficient, which measure the ability of groups of nodes to perform specialized processing, and global efficiency, which assesses the ability of brain regions to efficiently combine information. We computed partial correlations between these measures and DWMA volume, adjusted for confounders. Increasing DWMA volume was associated with decreased global efficiency of the entire very preterm brain and decreased local efficiency and clustering coefficient in a variety of regions supporting cognitive, linguistic, and motor function. We show that DWMA is associated with widespread decreased brain network efficiency, suggesting that it is pathologic and likely has adverse developmental consequences.
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Project description:PurposeTractography is the most anatomically accurate method for delineating white matter tracts in the brain, yet few studies have examined multiple tracts using tractography in patients with schizophrenia (SCZ). We analyze 5 white matter connections important in the pathophysiology of SCZ: uncinate fasciculus, cingulum bundle (CB), inferior longitudinal fasciculus (ILF), superior longitudinal fasciculus, and arcuate fasciculus (AF). Additionally, we investigate the relationship between diffusion tensor imaging (DTI) markers and neuropsychological measures.MethodsHigh-resolution DTI data were acquired on a 3 Tesla scanner in 30 patients with early-course SCZ and 30 healthy controls (HC) from the Boston Center for Intervention Development and Applied Research study. After manually guided tracts delineation, fractional anisotropy (FA), trace, radial diffusivity (RD), and axial diffusivity (AD) were calculated and averaged along each tract. The association of DTI measures with the Scales for the Assessment of Negative and Positive Symptoms and neuropsychological measures was evaluated.ResultsCompared to HC, patients exhibited reduced FA and increased trace and RD in the right AF, CB, and ILF. A discriminant analysis showed the possible use of FA of these tracts for better future group membership classifications. FA and RD of the right ILF and AF were associated with positive symptoms while FA and RD of the right CB were associated with memory performance and processing speed.ConclusionWe observed white matter alterations in the right CB, ILF, and AF, possibly caused by myelin disruptions. The structural abnormalities interact with cognitive performance, and are linked to clinical symptoms.
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Project description:OBJECTIVES:Idiopathic-generalized epilepsy (IGE) is currently considered to be a genetic disease without structural alterations on conventional MRI. However, voxel-based morphometry has shown abnormalities in IGE. Another method to analyze the microstructure of the brain is diffusion-tensor imaging (DTI). We sought to clarify which structural alterations are present in IGE and the most frequent subsyndrome juvenile myoclonic epilepsy (JME). EXPERIMENTAL DESIGN:We studied 25 patients (13 IGE and 12 JME) and 44 healthy controls with DTI. Fractional anisotropy (FA), mean diffusivity (MD), axial and radial diffusivity (AD/RD) were calculated and group differences were analyzed using tract-based spatial statistics (TBSS). Additionally we performed a target-based classification of TBSS results based on the Freesurfer cortical regions. PRINCIPLE OBSERVATIONS: TBSS showed widespread FA reductions as well as MD and RD increases in patients compared to controls. Affected areas were corpus callosum, corticospinal tract, superior and inferior longitudinal fasciculus and supplementary motor regions. No significant differences were found between JME and IGE subgroups. The target-based classification confirmed a particular involvement of the superior frontal gyrus (mesiofrontal area) in IGE/ME. CONCLUSIONS:IGE and JME patients showed clear microstructural alterations in several large white matter tracts. Similar findings have been reported in rodent models of IGE. Previous, region-of-interest-based DTI studies may have under-estimated the spatial extent of structural loss associated with generalized epilepsy. The comparison of clinically defined JME and IGE groups revealed no significant DTI differences in our cohort.
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Project description:Verbal memory is the most commonly impaired cognitive domain in patients with temporal lobe epilepsy (TLE). Although damage to the hippocampus and adjacent temporal lobe structures is known to contribute to memory impairment, little is known of the relative contributions of white versus gray matter structures, or whether microstructural versus morphometric measures of temporal lobe pathology are stronger predictors of impairment. We evaluate whether measures of temporal lobe pathology derived from diffusion tensor imaging (DTI; microstructural) versus structural MRI (sMRI; morphometric) contribute the most to memory performances in TLE, after controlling for hippocampal volume (HCV). DTI and sMRI were performed on 26 patients with TLE and 35 controls. Verbal memory was measured with the Logical Memory (LM) subtest of the Wechsler Memory Scale-III. Hierarchical regression analyses were performed to examine unique contributions of DTI and sMRI measures to verbal memory with HCV entered in block 1. In patients, impaired recall was associated with increased mean diffusivity (MD) of multiple fiber tracts that project through the temporal lobes. In addition, increased MD of the left cortical and bilateral pericortical white matter was associated with impaired recall. After controlling for left HCV, only microstructural measures of white matter pathology contributed to verbal recall. The best predictive model included left HCV and MD of the left inferior longitudinal fasciculus (ILF) and pericortical white matter beneath the left entorhinal cortex. This model explained 60% of the variance in delayed recall and revealed that MD of the left ILF was the strongest predictor. These data reveal that white matter microstructure within the temporal lobe can be used in conjunction with left HCV to enhance the prediction of verbal memory impairment, and speak to the complementary nature of DTI and sMRI for understanding cognitive dysfunction in epilepsy and possibly other memory disorders.
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