Cerebral white matter integrity in children with active versus remitted epilepsy 5 years after diagnosis

Disturbed white matter integrity on diffusion tensor imaging in young children with epilepsy

AIM

To evaluate whether abnormalities in white matter (WM) integrity are present in young children with epilepsy.

MATERIALS AND METHODS

Twelve children (3-6 years old) with epilepsy and six matched healthy controls were recruited for brain diffusion tensor imaging (DTI). Track-based spatial statistics (TBSS) was used to analyse and compare DTI indices of mean diffusivity (MD), fractional anisotropy (FA), axial and radial diffusivity (AD/RD) between patients and controls, and correlations between clinical variables and DTI parameters were analysed.

RESULTS

Compared with controls, patients showed increased FA in the left superior corona radiata and increased AD in the bilateral superior corona radiata. In children with generalised epilepsy, FA was increased in the left external capsule, while AD was decreased in the body of the corpus callosum, the left external capsule and the left superior longitudinal fasciculus. In those with focal epilepsy, FA was increased in the genu and body of the corpus callosum, and RD was decreased in the genu of the corpus callosum and left external capsule. Compared with partial epilepsy, generalised epilepsy was associated with increased FA in the right anterior corona radiata and decreased RD in the right anterior corona radiata and the genu and body of the corpus callosum. No significant correlations were observed between clinical variables and DTI parameters.

CONCLUSIONS

The results of this study indicate that the microstructure of the white matter is disturbed by epileptic discharges and a compensatory response occurs during early brain development.

A tract-based spatial statistics study of white matter integrity in epilepsy

OBJECTIVE

To explore the changes of cerebral white matter diffusion tensor in epilepsy.

METHODS

This study was a retrospective study based on diffusion tensor imaging (DTI). Twenty-six epileptic patients and 42 normal controls matched for sex, age and handedness were enrolled in our research. Based on the method of tract-based spatial statistics (TBSS), we analyzed the changes of each relevant parameter index of DTI in white matter of the brain in all subjects, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD).

RESULTS

In comparison with the control group, epileptic patients had decreased FA and elevated MD, AD, and RD in the anterior thalamic radiation, corticospinal tract, forceps major, forceps minor, cingulum, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, superior longitudinal fasciculus and uncinate fasciculus (P < 0.05).

CONCLUSION

Widespread white matter integrity was observed in epileptic patients, which may be the structural basis for the development of affective disorders, impaired cognition, and motor abnormalities.

Detection of endophenotypes associated with neuropsychiatric deficiencies in a mouse model of tuberous sclerosis complex using diffusion tensor imaging

Tuberous sclerosis complex (TSC) is a rare hereditary disease, which results from the mutation of either TSC1 or TSC2, and its clinical features include benign tumors and dysfunctions in numerous organs, including the brain. Many individuals with TSC manifest neuropsychiatric symptoms, such as learning impairments, cognitive deficits and anxiety. Current pharmacological treatment for TSC is the use of mTOR inhibitors. However, they are not effective in treating neuropsychiatric symptoms. We previously used curcumin, a diet-derived mTOR inhibitor, which possesses both anti-inflammatory and antiproliferative properties, to improve learning and memory deficits in Tsc2^+/- mice. Diffusion tensor imaging (DTI) provides microstructural information in brain tissue and has been used to study the neuropathological changes in TSC. In this study, we confirmed that the impaired recognition memory and increased anxiety-like behavior in Tsc2^+/- mice can be reversed by curcumin treatment. Second, we found altered fractional anisotropy and mean diffusivity in the anterior cingulate cortex and the hippocampus of the Tsc2^+/- mice, which may indicate altered circuitry. Finally, the mTOR complex 1 hyperactivity was found in the cortex and hippocampus, coinciding with abnormal cortical myelination and increased glial fibrillary acidic protein expression in the hippocampal CA1 of Tsc2^+/- mice, both of which can be rescued with curcumin treatment. Overall, DTI is sensitive to the subtle alterations that cannot be detected by conventional imaging, suggesting that noninvasive DTI may be suitable for longitudinally monitoring the in vivo neuropathology associated with the neuropsychiatric symptoms in TSC, thereby facilitating future clinical trials of pharmacological treatments.

Cognitive functions, electroencephalographic and diffusion tensor imaging changes in children with active idiopathic epilepsy

INTRODUCTION

Neurocognitive impairment represents one of the most common comorbidities occurring in children with idiopathic epilepsy. Diagnosis of the idiopathic form of epilepsy requires the absence of any macrostructural abnormality in the conventional MRI. Though changes can be seen at the microstructural level imaged using advanced techniques such as the Diffusion Tensor Imaging (DTI).

AIM OF THE WORK

The aim of this work is to study the correlation between the microstructural white matter DTI findings, the electroencephalographic changes and the cognitive dysfunction in children with active idiopathic epilepsy.

METHODS

A comparative cross-sectional study, included 60 children with epilepsy based on the Stanford-Binet 5th Edition Scores was conducted. Patients were equally assigned to normal cognitive function or cognitive dysfunction groups. The history of the epileptic condition was gathered via personal interviews. All patients underwent brain Electroencephalography (EEG) and DTI, which was analyzed using FSL.

RESULTS

The Fractional Anisotropy (FA) was significantly higher whereas the Mean Diffusivity (MD) was significantly lower in the normal cognitive function group than in the cognitive dysfunction group. This altered microstructure was related to the degree of the cognitive performance of the studied children with epilepsy. The microstructural alterations of the neural fibers in children with epilepsy and cognitive dysfunction were significantly related to the younger age of onset of epilepsy, the poor control of the clinical seizures, and the use of multiple antiepileptic medications.

CONCLUSION

Children with epilepsy and normal cognitive functions differ in white matter integrity, measured using DTI, compared with children with cognitive dysfunction. These changes have important cognitive consequences.

Psychomotor slowing is associated with anomalies in baseline and prospective large scale neural networks in youth with epilepsy

Purpose

Psychomotor slowing is a common but understudied cognitive impairment in epilepsy. Here we test the hypothesis that psychomotor slowing is associated with alterations in brain status reflected through analysis of large scale structural networks. We test the hypothesis that children with epilepsy with cognitive slowing at diagnosis will exhibit a cross-sectional and prospective pattern of altered brain development.

Methods

A total of 78 children (age 8–18) with new/recent onset idiopathic epilepsies underwent 1.5 T MRI with network analysis of cortical, subcortical and cerebellar volumes. Children with epilepsy were divided into slow and fast psychomotor speed groups (adjusted for age, intelligence and epilepsy syndrome).

Results

At baseline, slow-speed performers (SSP) presented lower modularity, lower global efficiency, higher transitivity, and lower number of hubs than fast-speed performers (FSP). Community structure in SSP exhibited poor association between cortical regions and both subcortical structures and the cerebellum while FSP presented well-defined communities. Prospectively, SSP displayed lower modularity but higher global efficiency and transitivity compared to FSP. Modules in FSP showed higher integration between and within themselves compared to SSP. SSP showed hubs mainly from frontal and temporal regions while in FSP were spread among frontal, temporal, parietal, subcortical areas and the left cerebellum.

Implications

Results suggest the presence of widespread alterations in large scale networks between fast- and slow-speed children with recent onset epilepsies both at baseline and 2 years later. Slower processing speed appears to be a marker of abnormal brain development antecedent to epilepsy onset as well as brain development over the 2 years following diagnosis.

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Baseline: slow-speed performers (SSP) showed lower modularity and global efficiency

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They also showed higher transitivity but fewer hubs than fast-speed performers (FSP)

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Prospective: SSP showed lower modularity, harmonic mean and higher transitivity

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Regional volume changes seem to be occurring as one in SSP, but more modular in FSP

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SSP showed hubs mainly from frontal and temporal while FSP showed them widespread

White matter disruption is associated with persistent seizures in tuberous sclerosis complex

BACKGROUND AND AIMS

White matter is diffusely altered in tuberous sclerosis complex (TSC), and these alterations appear to be more evident in subjects with a more severe neurologic phenotype. However, little is known on the correlation between white matter alterations and epilepsy in TSC. The aims of this study were to evaluate the effects of early onset and refractory seizures on white matter by using diffusion tensor imaging (DTI).

METHODS

We enrolled 20 children with TSC and epilepsy onset in the first 3years of life and grouped them according to seizure persistence or freedom. All patients underwent brain MRI with DTI. Specific ROIs have were placed to generate tracks to calculate fractional anisotropy (FA) and apparent diffusion coefficient (ADC). Statistical analysis was performed by ANOVA.

RESULTS

Children with persistent seizures presented an overall reduced FA, with statistically significant differences on the cingulum (right p=0.003, left p=0.016), the left cerebral peduncle (p=0.020), the superior cerebellar peduncles (right p=0.008, left p=0.002), the posterior limbs of internal capsule (right p=0.037, left p=0.015), the external capsule (right p=0.018, left p=0.031), the inferior frontooccipital fasciculus (right p=0.010, left p=0.026), and the temporal trunk (right p=0.017, left p=0.001).

CONCLUSIONS

Our study demonstrated that children with persistent seizures present more significant alterations of brain connectivity in areas crucial for global cognitive maturation, executive functions, and verbal abilities, implying a higher risk of cognitive impairment, attention-deficit hyperactivity disorder, and autism.

Longitudinal changes in diffusion properties in white matter pathways of children with tuberous sclerosis complex

BACKGROUND

Abnormal white matter development in patients with tuberous sclerosis complex, a multisystem hamartomatous disorder caused by aberrant neural proliferation and axonal maturation, may be associated with poorer neurocognitive outcomes. The purpose of this study is to identify predictors of longitudinal changes in diffusion properties of white matter tracts in patients with tuberous sclerosis complex.

METHODS

Diffusion magnetic resonance imaging was carried out in 17 subjects with tuberous sclerosis complex (mean age, 7.2 ± 4.4 years) with at least two magnetic resonance imaging scans (mean number of days between scans, 419.4 ± 105.4). There were 10 males; 5 of 17 had autism spectrum disorder and 10 of 17 had epilepsy. Regions of interest were placed to delineate the internal capsule/corona radiata, cingulum, and corpus callosum. The outcomes were mean change in apparent diffusion coefficient and fractional anisotropy. Data were analyzed using Pearson's correlation and multiple linear regression analyses.

RESULTS

Gender was a significant predictor of mean change in apparent diffusion coefficient in the left internal capsule, right and left cingulum bundles, and corpus callosum and a significant predictor of mean change in fractional anisotropy in the corpus callosum. Epilepsy was a significant predictor of mean change in apparent diffusion coefficient in the left internal capsule. Autism spectrum disorder was not predictive of diffusion changes in any of the studied pathways.

CONCLUSION

Clinical variables, including gender and epilepsy, have an effect on the development of white matter pathways. These variables should be taken into consideration when counseling tuberous sclerosis complex patients and in future imaging studies in this population.

White matter abnormalities associate with type and localization of focal epileptogenic lesions

OBJECTIVE

To evaluate white matter (WM) integrity of distinct groups of patients with antiepileptic drug (AED)-resistant localization-related epilepsies.

METHODS

We used diffusion tensor imaging (DTI) fiber-tractography and voxel-based morphometry (VBM) to investigate differences of WM micro- and macrostructural integrity in patients with different drug-resistant localization-related epilepsies: 17 with temporal lobe epilepsy with magnetic resonance imaging (MRI) signs of hippocampal sclerosis (TLE-HS), 17 with TLE and normal MRI (TLE-NL), 14 with frontal lobe epilepsy and subtle MRI signs of focal cortical dysplasia (FLE-FCD), and 112 healthy controls. We performed fiber-tractography using a semiautomatic deterministic method to yield average fractional anisotropy (FA), axial (AD), and radial (RD) diffusivity ipsilateral and contralateral to the epileptogenic zone of the following tracts based on their functional and anatomic relevance: body of fornix (BoF), body of cingulum (BoC), inferior frontal occipital (IFO), and uncinate fasciculi (UF). In addition, we performed VBM of the WM maps to assess macrostructural integrity differences among groups.

RESULTS

TLE-HS had ipsilateral and contralateral decreased FA and increased RD for all tracts. VBM showed WM alterations mainly in the ipsilateral parahippocampal region and contralateral superior temporal gyrus. FLE-FCD showed bilateral FA decreases only in the BoC and ipsilateral RD increases also in the BoC. VBM showed WM reduction mainly in the ipsilateral precuneus and posterior and anterior cingulum. No significant WM alterations were found in the TLE-NL in DTI or VBM analysis.

SIGNIFICANCE

WM abnormalities differ in distinct AED-resistant localization-related epilepsies. The diverse distribution of the WM damage in these patients suggests that the localization of the epileptic networks may play a role in the WM burden. However, the distinct degree of this damage, more accentuated in TLE-HS, also suggests that the underlying cause of the epilepsy is probably an additional factor to explain this WM damage.

Individual classification of children with epilepsy using support vector machine with multiple indices of diffusion tensor imaging

INTRODUCTION

Support vector machines (SVM) have recently been demonstrated to be useful for voxel-based MR image classification. In the present study we sought to evaluate whether this method is feasible in the classification of childhood epilepsy intractability based on diffusion tensor imaging (DTI), with adequate accuracy. We applied SVM in conjunction DTI indices of fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD). DTI studies have reported white matter abnormalities in childhood-onset epilepsy, but the mechanisms underlying these abnormalities are not well understood. The aim of this study was to examine the relationship between epileptic seizures and cerebral white matter abnormalities identified by DTI in children with active compared to remitted epilepsy utilizing an automated and unsupervised classification method.

METHODS

The DTI data were tensor-derived indices including FA, MD, AD and RD in 49 participants including 20 children with epilepsy 5-6 years after seizure onset as compared to healthy controls. To determine whether there was normalization of white matter diffusion behavior following cessation of seizures and treatment, the epilepsy subjects were grouped into those with active versus remitted epilepsy. Group comparisons were previously made examining FA, MD and RD via whole-brain tract-based spatial statistics (TBSS). The SVM analysis was undertaken with the WEKA software package with 10-fold cross validation. Weighted sensitivity, specificity and accuracy were measured for all the DTI indices for two classifications: (1) controls vs. all children with epilepsy and (2) controls vs. children with remitted epilepsy vs. children with active epilepsy.

RESULTS

Using TBSS, significant differences were identified between controls and all children with epilepsy, between controls and children with active epilepsy, and also between the active and remitted epilepsy groups. There were no significant differences between the remitted epilepsy and controls on any DTI measure. In the SVM analysis, the best predictor between controls and all children with epilepsy was MD, with a sensitivity of 90-100% and a specificity between 96.6 and 100%. For the three-way classification, the best results were for FA with 100% sensitivity and specificity.

CONCLUSION

DTI-based SVM classification appears promising for distinguishing children with active epilepsy from either those with remitted epilepsy or controls, and the question that arises is whether it will prove useful as a prognostic index of seizure remission. While SVM can correctly identify children with active epilepsy from other groups' diagnosis, further research is needed to determine the efficacy of SVM as a prognostic tool in longitudinal clinical studies.