Article

White matter abnormalities in children and adolescents with temporal lobe epilepsy

MEG Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45220, USA.
Magnetic Resonance Imaging (Impact Factor: 2.09). 11/2010; 28(9):1290-8. DOI: 10.1016/j.mri.2010.03.046
Source: PubMed

ABSTRACT

The widespread propagation of synchronized neuronal firing in seizure disorders may affect cortical and subcortical brain regions. Diffusion tensor imaging (DTI) can noninvasively quantify white matter integrity. The purpose of this study was to investigate the abnormal changes of white matter in children and adolescents with focal temporal lobe epilepsy (TLE) using DTI.
Eight patients with clinically diagnosed TLE and eight age- and sex-matched healthy controls were studied. DTI images were obtained with a 3-T magnetic resonance imaging scanner. The epileptic foci were localized with magnetoencephalography. Fractional anisotropy (FA), mean diffusivity (MD), parallel (λ(||)) and perpendicular (λ(⊥)) diffusivities in the genu of the corpus callosum, splenium of the corpus callosum (SCC), external capsule (EC), anterior limbs of the internal capsule (AIC), and the posterior limbs of the internal capsule (PIC) were calculated. The DTI parameters between patients and controls were statistically compared. Correlations of these DTI parameters of each selected structure with age of seizure onset and duration of epilepsy were analysed.
In comparison to controls, both patients' seizure ipsilateral and contralateral had significantly lower FA in the AIC; PIC and SCC and higher MD, λ(||) and λ(⊥) in the EC, AIC, PIC and SCC. The MD, λ(||) and λ(⊥) were significantly correlated with age of seizure onset in the EC and PIC. λ(||) was significantly correlated with the duration of epilepsy in the EC and PIC.
The results of the present study indicate that children and adolescents with TLE had significant abnormalities in the white matter in the hemisphere with seizure foci. Furthermore, these abnormalities may extend to the other brain hemisphere. The age of seizure onset and duration of epilepsy may be important factors in determining the extent of influence of children and adolescents TLE on white matter.

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    • "One strength of the current study is the large number of TLE patients (n = 28) investigated compared to prior studies (Ahmadi et al., 2009;Arfanakis et al., 2002;Concha et al., 2009;Govindan et al., 2008;Knake et al., 2009;Lin et al., 2008;McDonald et al., 2008;Meng et al., 2010;Nilsson et al., 2008;Rodrigo et al., 2007;Wang et al., 2010). This enabled separate investigation of left and right TLE patients, and was more powerful in examining progressive changes in TLE compared to prior studies. "
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    ABSTRACT: Purpose: Temporal lobe epilepsy (TLE) is thought to be a network disease and structural changes using diffusion tensor imaging (DTI) have been shown. However, lateralized differences in the structural integrity of TLE, as well as changes in structural integrity with longer disease duration, have not been well defined. Methods: We examined the fractional anisotropy (FA) and mean diffusivity (MD) in the hippocampus, as well as its primary (cingulum and fornix) and remote (uncinate and external capsule) connections in both right and left TLE. Changes in diffusion measures over the disease course were examined by correlating FA and MD in the various structures with epilepsy duration. The potential for each measure of anisotropy and diffusivity as a marker of TLE laterality was investigated using random forest (RF) analysis. Results: MD was increased in the bilateral hippocampus, cingulum, fornix and the right external capsule in both left and right TLE compared to controls. In addition, left TLE exhibited an increased MD in the ipsilateral uncinate fasciculus and bilateral external capsules. A decrease in FA was seen in the left cingulum in left TLE. RF analysis demonstrated that MD of the right hippocampus and FA of the left external capsule were important predictors of TLE laterality. An association of increased MD with epilepsy duration was seen in the left hippocampus in left TLE. Conclusion: Evidence of disrupted white matter architecture in the hippocampus and its primary and remote connections were demonstrated in TLE. While changes in the hippocampus and cingulum were more prominent in right TLE, remote changes were more prominent in left TLE. MD of the right hippocampus and FA of the left external capsule were found to be the strongest structural predictors of TLE laterality. Changes associated with duration of epilepsy indicated that changes in structural integrity may be progressive over the disease course. This study illustrates the potential of structural diffusion tensor imaging in elucidating pathophysiology, enhancing diagnosis and assisting prognostication.
    No preview · Article · Dec 2015 · Epilepsy research
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    • "Advances in the development and application of diffusion tensor imaging (DTI) have allowed for investigating the organization of human brain white matter (WM) (Hagmann et al., 2008; Iturria-Medina et al., 2008; Gong et al., 2009a). Numerous DTI studies of TLE have reported brain WM abnormalities in TLE according to DTI analysis, such as the external capsule, corpus callosum (Meng et al., 2010), fornix, cingulum (Concha et al., 2009), uncinate fasciculus, arcuate fasciculus (Lin et al., 2008), and inferior fronto-occipital fasciculus (McDonald et al., 2008a). Even though the widespread WM damage in TLE suggests disrupted structural integrity derived from a systemic disorder, few studies have investigated the disrupted WM organizations in TLE patients from a system level. "
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    ABSTRACT: Mesial temporal lobe epilepsy (mTLE) is the most common drug-refractory focal epilepsy in adults. Although previous functional and morphological studies have revealed the abnormalities in the brain networks of mTLE, the topological organization of the brain white matter (WM) networks in mTLE patients is still ambiguous. In this study, we constructed brain WM networks for 14 left mTLE patients and 22 age- and gender-matched normal controls using diffusion tensor tractography and estimated the alterations of network properties in the mTLE brain networks using graph theoretical analysis. We found that the networks for both the mTLE and the controls exhibited prominent small-world properties, suggesting a balanced topology of integration and segregation. However, the brain WM networks of mTLE showed significant increased characteristic path length but significant decreased global efficiency, which indicate disruption in the organization of the brain WM networks in mTLE. Moreover, we found significant between-group differences in the nodal properties in several brain regions, such as the left superior temporal gyrus, left hippocampus, the right occipital and right temporal cortices. The robustness analysis showed that the results were likely to be consistent for the networks constructed with different definitions of node and edge weight. Taken together, our findings may suggest an adverse effect of epileptic seizures on the organization of large-scale brain WM networks in mTLE.
    Full-text · Article · Sep 2014 · Neuroscience
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    • "There are also DTI changes in the thalami bilaterally (Kim et al., 2010; Wang et al., 2010). While most studies are done in adults, children and adolescents with TLE also have significant WM abnormalities (Meng et al., 2010). A metaanalysis of 13 studies shows WM structural integrity is affected in the ipsilateral hemisphere more than contralaterally, with tracts closely connected with the affected temporal lobe being the most disturbed (Otte et al., 2012). "
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    ABSTRACT: Limbic epilepsy refers to a condition that consists of epileptic seizures that originate in or preferentially involve the limbic system. The majority of cases are medically refractory, necessitating surgical resection when possible. However, even resection of structures thought to be responsible for seizure generation may not leave a patient seizure free. While mesial temporal lobe limbic structures are centrally involved, there is growing evidence that the epileptogenic network consists of a broader area, involving structures outside of the temporal lobe and the limbic system. Information on structural, functional, and metabolic connectivity in patients with limbic epilepsy is available from a large body of studies employing methods such as MRI, EEG, MEG, fMRI, PET, and SPECT scanning, implicating the involvement of various brain regions in the epileptogenic network. To date, there are no consistent and conclusive findings to define the exact boundaries of this network, but it is possible that in the future studies of network connectivity in the individual patient may allow more tailored treatment and prognosis in terms of surgical resection.
    Full-text · Article · Aug 2014 · International Review of Neurobiology
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