Presurgical Evaluation of Epilepsy by Brain Diffusion: MR‐detected Effects of Flumazenil on the Epileptogenic Focus

Konermann, Stefan; Marks, Sonja; Ludwig, Tanja; Weber, W.; Greiff, Armin de; Dörfler, Arnd; Leonhardt, Georg; Wiedemayer, H.; Diener, Hans‐Christoph; Hufnagel, A.

doi:10.1046/j.1528-1157.2003.25702.x

Cited by 29 publications

(30 citation statements)

References 32 publications

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“…Epileptic foci in the neocortical aspect of the brain have also been shown to have increased ADC values in humans. This is considered to be the result of an enlargement of the intercellular spaces caused degenerative neuronal loss due to hippocampal atrophy . Kainic acid induced complex partial status epilepticus lead to a reduction in ADC values.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion‐weighted Magnetic Resonance Imaging of the Normal Canine Brain

Hartmann

Söffler

Failing

et al. 2014

Vet Radiology Ultrasound

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Diffusion-weighted imaging (DWI) MRI has been primarily reported as a method for diagnosing cerebrovascular disease in veterinary patients. In humans, clinical applications for diffusion-weighted MRI have also included epilepsy, Alzheimer's, and Creutzfeld-Jakob disease. Before these applications can be developed in veterinary patients, more data on brain diffusion characteristics are needed. Therefore, the aim of this study was to evaluate the distribution of diffusion in the normal canine brain. Magnetic resonance imaging of the brain was performed in ten, clinically normal, purpose-bred beagle dogs. On apparent diffusion coefficient maps, regions of interest were drawn around the caudate nucleus, thalamus, piriform lobe, hippocampus, semioval center, and cerebral cortex. Statistically significant differences in mean apparent diffusion coefficient were found for the internal capsule, hippocampus, and thalamus. The highest apparent diffusion coefficient (1044.29 ± 165.21 μm(2)/s (mean ± SD (standard deviation)) was detected in the hippocampus. The lowest apparent diffusion coefficient was measured in the semioval center (721.39 ± 126.28 μm(2)/s (mean ± SD)). Significant differences in mean apparent diffusion coefficients of the caudate nucleus, thalamus, and piriform lobe were found by comparing right and left sides. Differences between brain regions may occur due to differences in myelination, neural density, or fiber orientation. The reason for the differences between right and left sides remains unclear. Data from the current study provide background for further studies of diffusion changes in dogs with brain disease.

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Section: Introductionmentioning

confidence: 99%

“…Therefore, the detection of changes is based on the comparison of the right and left side of certain brain areas (e.g. hippocampus, thalamus, cerebral cortex, pulvinar nuclei) . Changes after seizures are short‐lived and are best detected within 30 min after onset.…”

Section: Introductionmentioning

confidence: 99%

Diffusion‐weighted Magnetic Resonance Imaging of the Normal Canine Brain

Hartmann

Söffler

Failing

et al. 2014

Vet Radiology Ultrasound

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“…Water diffusion is altered by the structures of gray matter (12). DWI can be used to evaluate morphological changes in cortical microstructures (13)(14)(15)(16)(17)(18)(19) and can function as a probe to estimate immediate and transient changes in water diffusion that are associated with ischemia (17) or neuronal firing (13,16,19) and delayed and persistent changes that are associated with long-term plasticity in experimental settings (20) or pathological conditions (15,18,21). Here, using DWI techniques, we examined whether subthreshold, low-frequency (<1 Hz) rTMS to the left primary motor cortex (M1), a protocol that induces LTD-like plasticity (22, 23), increased water diffusion in the left M1 and other regions after the end of rTMS.…”

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confidence: 99%

Water diffusion reveals networks that modulate multiregional morphological plasticity after repetitive brain stimulation

Abe

Fukuyama

Mima

2014

Proc. Natl. Acad. Sci. U.S.A.

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Repetitive brain stimulation protocols induce plasticity in the stimulated site in brain slice models. Recent evidence from network models has indicated that additional plasticity-related changes occur in nonstimulated remote regions. Despite increasing use of brain stimulation protocols in experimental and clinical settings, the neural substrates underlying the additional effects in remote regions are unknown. Diffusion-weighted MRI (DWI) probes water diffusion and can be used to estimate morphological changes in cortical tissue that occur with the induction of plasticity. Using DWI techniques, we estimated morphological changes induced by application of repetitive transcranial magnetic stimulation (rTMS) over the left primary motor cortex (M1). We found that rTMS altered water diffusion in multiple regions including the left M1. Notably, the change in water diffusion was retained longest in the left M1 and remote regions that had a correlation of baseline fluctuations in water diffusion before rTMS. We conclude that synchronization of water diffusion at rest between stimulated and remote regions ensures retention of rTMS-induced changes in water diffusion in remote regions. Synchronized fluctuations in the morphology of cortical microstructures between stimulated and remote regions might identify networks that allow retention of plasticityrelated morphological changes in multiple regions after brain stimulation protocols. These results increase our understanding of the effects of brain stimulation-induced plasticity on multiregional brain networks. DWI techniques could provide a tool to evaluate treatment effects of brain stimulation protocols in patients with brain disorders.R epetitive electrical brain stimulation induces long-term potentiation (LTP) or depression (LTD) at the stimulated neurons (1-4). In humans, repetitive transcranial magnetic stimulation (rTMS) alters cortical excitability at the stimulated site that outlasts the end of the stimulation, analogous to LTP or LTD in animal models (5, 6), but also affects remote regions, possibly through transsynaptic pathways (7,8). Although rTMS has been proposed as a potential treatment for neurological and psychiatric disorders (9, 10) and as a method to facilitate learning (11), the neural substrates underlying the effects of rTMS on remote regions of the brain remain poorly understood.Diffusion-weighted MRI (DWI) probes water diffusion, a thermal physical phenomena that is characterized by random motion of water molecules (12). Water diffusion is altered by the structures of gray matter (12). DWI can be used to evaluate morphological changes in cortical microstructures (13)(14)(15)(16)(17)(18)(19) and can function as a probe to estimate immediate and transient changes in water diffusion that are associated with ischemia (17) or neuronal firing (13,16,19) and delayed and persistent changes that are associated with long-term plasticity in experimental settings (20) or pathological conditions (15,18,21). Here, using DWI techniques, we examined whether subt...

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“…The potential capability of diffusion MRI to demarcate epileptic cortex has been discussed in several previous studies (Rugg‐Gunn et al., ; Konermann et al., ; Guye et al., ; Roberts, ). The present study lends further support to this claim by demonstrating contrasting patterns of diffusion abnormalities between epileptic and nonepileptic as well as normal cortex.…”

Section: Discussionmentioning

confidence: 95%

Surface‐based laminar analysis of diffusion abnormalities in cortical and white matter layers in neocortical epilepsy

et al. 2013

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Summary Purpose Microstructural alterations seen in the epileptic cortex have been implicated as a cause and also result of multiple seizure activity. In the present study, we evaluated water diffusion changes at different cortical thickness fractions and in the underlying white matter of the epileptic cortex and compared them with electrographically normal cortex and also with corresponding cortical regions of healthy controls. Methods We selected 18 children with normal MRI who underwent two-stage epilepsy surgery to control seizures of neocortical origin, and compared their MR images with those of 18 age-matched healthy controls. First, delineation of the grey-white and grey-pial intersection surfaces was performed on high-resolution volumetric T1 MR images. Using the delineated surfaces as reference, diffusion values were measured at different cortical thickness fractions and in the underlying white matter at various depths, using diffusion tensor imaging (DTI). Cortical regions representing seizure onset and electrographically normal cortex were differentiated by electrocorticography in the epilepsy patients. Key findings We observed different patterns of diffusion abnormalities in both the seizure onset and electrographically normal cortical regions when compared to healthy controls. In the seizure onset regions, a marked increase in diffusivity was noted in the cortical grey matter and this increase was most pronounced in the outer fraction of the grey matter. Similarly, increased diffusivity was noted in the white matter underlying the epileptic cortex. The electrographically normal cortex, in contrast, showed decreased diffusivity in inner and middle cortical fractions compared to the controls. The white matter underlying the electrographically normal cortex did not show any difference in diffusivity between the epileptic children and controls. Finally, both the cortical grey matter and the underlying white matter regions showed decreased anisotropy in epileptic as well as electrographically normal regions when compared to controls. Significance Our results suggest specific patterns of diffusion changes in the cortical fractions and the underlying white matter of the epileptic region compared to electrographically normal and normal control regions. The abnormal increase in diffusivity of the superficial cortex might be associated with microstructural abnormalities commonly seen in layers II through IV of epileptic cortex. Such combined use of a high-resolution structural image to extract the laminar diffusion values, which are highly sensitive to microstructural alterations, could be of clinical value in localizing epileptogenic cortex.

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Presurgical Evaluation of Epilepsy by Brain Diffusion: MR‐detected Effects of Flumazenil on the Epileptogenic Focus

Cited by 29 publications

References 32 publications

Diffusion‐weighted Magnetic Resonance Imaging of the Normal Canine Brain

Diffusion‐weighted Magnetic Resonance Imaging of the Normal Canine Brain

Water diffusion reveals networks that modulate multiregional morphological plasticity after repetitive brain stimulation

Surface‐based laminar analysis of diffusion abnormalities in cortical and white matter layers in neocortical epilepsy

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