Objectives
Focal cortical dysplasia (FCD) is a major cause of drug‐resistant focal epilepsy in children, and the clinicopathological classification remains a challenging issue in daily practice. With ...the recent progress in DNA methylation–based classification of human brain tumors we examined whether genomic DNA methylation and gene expression analysis can be used to also distinguish human FCD subtypes.
Methods
DNA methylomes and transcriptomes were generated from massive parallel sequencing in 15 surgical FCD specimens, matched with 5 epilepsy and 6 nonepilepsy controls.
Results
Differential hierarchical cluster analysis of DNA methylation distinguished major FCD subtypes (ie, Ia, IIa, and IIb) from patients with temporal lobe epilepsy patients and nonepileptic controls. Targeted panel sequencing identified a novel likely pathogenic variant in DEPDC5 in a patient with FCD type IIa. However, no enrichment of differential DNA methylation or gene expression was observed in mechanistic target of rapamycin (mTOR) pathway–related genes.
Significance
Our studies extend the evidence for disease‐specific methylation signatures toward focal epilepsies in favor of an integrated clinicopathologic and molecular classification system of FCD subtypes incorporating genomic methylation.
Malformations of cortical development (MCD) comprise a broad spectrum of structural brain lesions frequently associated with epilepsy. Disease definition and diagnosis remain challenging and are ...often prone to arbitrary judgment. Molecular classification of histopathological entities may help rationalize the diagnostic process. We present a retrospective, multi-center analysis of genome-wide DNA methylation from human brain specimens obtained from epilepsy surgery using EPIC 850 K BeadChip arrays. A total of 308 samples were included in the study. In the reference cohort, 239 formalin-fixed and paraffin-embedded (FFPE) tissue samples were histopathologically classified as MCD, including 12 major subtype pathologies. They were compared to 15 FFPE samples from surgical non-MCD cortices and 11 FFPE samples from post-mortem non-epilepsy controls. We applied three different statistical approaches to decipher the DNA methylation pattern of histopathological MCD entities, i.e., pairwise comparison, machine learning, and deep learning algorithms. Our deep learning model, which represented a shallow neuronal network, achieved the highest level of accuracy. A test cohort of 43 independent surgical samples from different epilepsy centers was used to test the precision of our DNA methylation-based MCD classifier. All samples from the test cohort were accurately assigned to their disease classes by the algorithm. These data demonstrate DNA methylation-based MCD classification suitability across major histopathological entities amenable to epilepsy surgery and age groups and will help establish an integrated diagnostic classification scheme for epilepsy-associated MCD.
Polymicrogyria (PMG) is a developmental cortical malformation characterized by an excess of small and frustrane gyration and abnormal cortical lamination. PMG frequently associates with seizures. The ...molecular pathomechanisms underlying PMG development are not yet understood. About 40 genes have been associated with PMG, and small copy number variations have also been described in selected patients. We recently provided evidence that epilepsy-associated structural brain lesions can be classified based on genomic DNA methylation patterns. Here, we analyzed 26 PMG patients employing array-based DNA methylation profiling on formalin-fixed paraffin-embedded material. A series of 62 well-characterized non-PMG cortical malformations (focal cortical dysplasia type 2a/b and hemimegalencephaly), temporal lobe epilepsy, and non-epilepsy autopsy controls was used as reference cohort. Unsupervised dimensionality reduction and hierarchical cluster analysis of DNA methylation profiles showed that PMG formed a distinct DNA methylation class. Copy number profiling from DNA methylation data identified a uniform duplication spanning the entire long arm of chromosome 1 in 7 out of 26 PMG patients, which was verified by additional fluorescence in situ hybridization analysis. In respective cases, about 50% of nuclei in the center of the PMG lesion were 1q triploid. No chromosomal imbalance was seen in adjacent, architecturally normal-appearing tissue indicating mosaicism. Clinically, PMG 1q patients presented with a unilateral frontal or hemispheric PMG without hemimegalencephaly, a severe form of intractable epilepsy with seizure onset in the first months of life, and severe developmental delay. Our results show that PMG can be classified among other structural brain lesions according to their DNA methylation profile. One subset of PMG with distinct clinical features exhibits a duplication of chromosomal arm 1q.
Precise robotic or stereotactic implantation of stereoelectroencephalography (sEEG) electrodes relies on the exact referencing of the planning images in order to match the patient's anatomy to the ...stereotactic device or robot. We compared the accuracy of sEEG electrode implantation with stereotactic frame versus laser scanning of the face based on computed tomography (CT) or magnetic resonance imaging (MRI) datasets for referencing.
The accuracy was determined by calculating the Euclidian distance between the planned trajectory and the postoperative position of the sEEG electrode, defining the entry point error (EPE) and the target point error (TPE). The sEEG electrodes (n = 171) were implanted with the robotic surgery assistant (ROSA) in 19 patients. Preoperative trajectory planning was performed on three-dimensional (3D) MRI datasets. Referencing was accomplished either by performing (A) 1.25-mm slice CT with the patient's head fixed in a Leksell stereotactic frame (CT-frame, n = 49), fused with a 3D-T1-weighted, contrast enhanced- and T2-weighted 1.5 Tesla (T) MRI; (B) 1.25 mm CT (CT-laser, n = 60), fused with 3D-3.0-T MRI; (C) 3.0-T MRI T1-based laser scan (3.0-T MRI-laser, n = 56) or (D) in one single patient, because of a pacemaker, 3D-1.5-T MRI T1-based laser scan (1.5-T MRI-laser, n = 6).
In (A) CT-frame referencing, the mean EPE amounted to 0.86 mm and the mean TPE amounted to 2.28 mm (n = 49). In (B) CT-laser referencing, the EPE amounted to 1.85 mm and the TPE to 2.41 mm (n = 60). In (C) 3.0-T MRI-laser referencing, the mean EPE amounted to 3.02 mm and the mean TPE to 3.51 mm (n = 56). In (D) 1.5-T MRI, surprisingly the mean EPE amounted only to 0.97 mm and the TPE to 1.71 mm (n = 6). In 3 cases using CT-laser and 1 case using 3.0 T MRI-laser for referencing, small asymptomatic intracerebral hemorrhages were detected. No further complications were observed.
Robot-guided sEEG electrode implantation using CT-frame referencing and CT-laser-based referencing is most accurate and can serve for high precision placement of electrodes. In contrast, 3.0-T MRI-laser-based referencing is less accurate, but saves radiation. Most trajectories can be reached if alternative routes over less vascularized brain areas are used.
This article is part of the Special Issue "Individualized Epilepsy Management: Medicines, Surgery and Beyond".
Focal cortical dysplasias (FCD) which represent a composite group of cortical malformations are increasingly recognized as morphological substrate for severe therapy-refractory epilepsy in children ...and young adults. However, presurgical evaluation remains challenging as not all FCD variants can be reliably detected by high-resolution magnetic resonance imaging (MRI). Here, we studied a cohort of 52 epilepsy patients with neuropathological evidence for FCD using the 2011 classification of the International League against Epilepsy (ILAE) and systematically analysed those histopathologic features applicable also for MRI diagnostics. Histopathologic parameters included quantitative measurements of cellular profiles, cortical thickness, heterotopic neurons in white matter, and myelination that were compared between FCD subtypes and age-/localization-matched controls (
n
= 36) using multivariate analysis. Dysmorphic neurons in both FCD Type II variants showed significantly increased diameter of their cell bodies and nuclei. Cortical thickness was also increased with a distinct loss of myelin content specifying FCD Type IIb from IIa. The data further suggested that myelination deficits in FCD Type IIb result from compromised oligodendroglial lineage differentiation and we concluded that the “transmantle sign” is a unique finding in FCD Type IIb. In contrast, FCD Type Ia was characterized by a smaller cortical ribbon and higher neuronal densities, but these parameters failed to reach statistical significance (considering age- and location-dependent variability in controls). All FCD variants showed abnormal grey–white matter boundaries with increased numbers of heterotopic neurons. Similar results were obtained also at deep white matter location. Thus, many FCD variants may indeed escape visual MRI inspection, but suspicious areas with increased or decreased cortical thickness as well as grey–white matter blurring may be uncovered using post-processing protocols of neuroimaging data. The systematic analysis of well-specified histopathological features could be helpful to improve sensitivity and specificity in MRI detection during pre-surgical work-up of patients with drug-resistant focal epilepsies.
Purpose To validate four established, child-friendly functional magnetic resonance imaging (fMRI) language tasks (word chain task WCT, vowel identification task VIT, synonym task SYT and beep story ...task BST) in a predominantly pediatric cohort. Methods Intracarotid amobarbital procedures (IAP) (nâ¯= 17) and unchanged language after hemispherotomy (nâ¯= 6) were used as gold standards. The fMRI activations of nine regions of interest (ROI) in the frontal, temporal and parietal lobes as well as in the cerebellum were visually assessed in 23 fMRI examinations (in total 117 fMRI task sessions) of 23 patients (age range 10.0-23.0 years) with drug-refractory epilepsies. Results The ROIs were considered valid when they showed activation in more than 25% of all sessions for the respective task and never showed false lateralization (in comparison to gold standards). Thus, 13 valid, task-specific ROIs were identified: 5 ROIs for the WCT (frontal operculum, inferior frontal gyrus, middle frontal gyrus, intraparietal sulcus, cerebellum), 3 ROIs for the VIT (frontal operculum, inferior frontal gyrus, middle frontal gyrus), 3 ROIs for the SYT (frontal operculum, inferior frontal gyrus, temporal language area) and 2 ROIs for the BST (inferior frontal gyrus, middle frontal gyrus). Conclusion Clinical fMRI using the battery of four tasks is a valid tool for lateralizing language in children, adolescents and young adults. Each task proved to be specifically useful, which confirms that applying different tasks increases the probability of diagnosing language dominance in presurgical candidates.
Abstract Objective: To analyze and to discuss whether by paying attention to the many recent advancements in the field of pediatric epilepsy surgery catastrophic childhood epilepsies caused by ...definitive or suspected structural lesions can be prevented more often these days in comparison to the past. Methods: Based on data from the literature and supplemented by the authors own experience, risks for children suffering from structural focal epilepsies that the epilepsy becomes catastrophic and ways how such evolutions can possibly be prevented are discussed for the different lesion-types separately – in the order of their frequency as they are seen at pediatric epilepsy surgery centers. Special emphasis is put on data regarding attempts to prevent permanent severe mental retardations. Results: There are common factors predisposing to catastrophic courses in all structural focal epilepsies, such as early onset and a longer duration of epilepsy (with respect to cognitive outcome not with respect to seizure outcome), but there are also differences. Moreover the better perspectives now in comparison to the past for children with conditions like MRI-negative focal epilepsies, subtle focal cortical dysplasias, epilepsies post hypoxic–ischemic events, tuberous sclerosis etc. are not well recognized yet. While there is agreement that “early” (and successful) surgery is essential in many instances to prevent permanent mental retardations there is insufficient data regarding the issue that “early surgery “might not be early enough under certain circumstances and there is also only little data regarding variables which would allow to keep calm when a child is presenting with early onset difficult to control seizures. One of the biggest changes seen over the last decade is the fact that children with very severe epilepsies, who have unilateral lesions, but “generalized” seizures and/or “generalized” EEGs, are not excluded anymore from considerations for epilepsy surgery. Even children with bilateral lesions can be surgical candidates. Conclusion: The gradually widening spectrum of indications for epilepsy surgery in children is resulting in an increasing number of preventions of catastrophic epilepsies. Insufficient data regarding timing of surgery in order to prevent permanent mental retardations are calling for prospective multi-center studies.
As a member of the multidrug-resistance associated protein (MRP) family, MRP2 affects the brain entry of different endogenous and exogenous compounds. Considering the role of this transporter at the ...blood-brain barrier, the regulation is of particular interest. However, there is limited knowledge regarding the factors that regulate MRP2 in neurologic disease states. Thus, we addressed the hypothesis that MRP2 might be affected by a glutamate-induced signaling pathway that we previously identified as one key mechanism in the regulation of P-glycoprotein. Studies in isolated porcine brain capillaries confirmed that glutamate and N-methyl-d-aspartic acid (NMDA) exposure upregulates expression and function of MPR2. The involvement of the NMDA receptor was further suggested by the fact that the NMDA receptor antagonist MK-801 (5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzoa,dcyclohepten-5,10-imine, as well as the NMDA receptor glycine binding site antagonist L-701,324 7-chloro-4-hydroxy-3-(3-phenoxy)phenyl-2(1H)-quinolinone, prevented the impact of glutamate. A role of cyclooxygenase-2 was indicated by coincubation with the cyclooxygenase-2 inhibitor celecoxib and the cyclooxygenase-1/-2 inhibitor indomethacin, which both efficaciously abolished a glutamate-induced upregulation of MRP2. Translational studies in human capillaries from surgical specimen demonstrated a relevant MRP2 efflux function and indicated an effect of glutamate exposure as well as its prevention by cyclooxygenase-2 inhibition. Taken together the findings provide first evidence for a role of a glutamate-induced NMDA receptor/cyclooxygenase-2 signaling pathway in the regulation of MRP2 expression and function. The response to excessive glutamate concentrations might contribute to overexpression of MRP2, which has been reported in neurologic diseases including epilepsy. The overexpression might have implications for brain access of various compounds including therapeutic drugs.
Objective:
KMT2B-related dystonia is a progressive childhood-onset movement disorder, evolving from lower-limb focal dystonia into generalized dystonia. With increasing age, children frequently show ...prominent laryngeal or facial dystonia manifesting in dysarthria. Bilateral deep brain stimulation of the globus pallidus internus (GPi-DBS) is reported to be an efficient therapeutic option. Especially improvement of dystonia and regaining of independent mobility is commonly described, but detailed information about the impact of GPi-DBS on dysarthria and speech is scarce.
Methods:
We report the 16-months outcome after bilateral GPi-DBS in an 8-year-old child with KMT2B-related dystonia caused by a
de-novo
c.3043C>T (p.Arg1015
*
) non-sense variant with special emphasis on dysarthria and speech. We compare the outcome of our patient with 59 patients identified through a PubMed literature search.
Results:
A remarkable improvement of voice, articulation, respiration and prosodic characteristics was seen 16 months after GPi-DBS. The patients' speech intelligibility improved. His speech became much more comprehensible not only for his parents, but also for others. Furthermore, his vocabulary and the possibility to express his feelings and wants expanded considerably.
Conclusion:
A positive outcome of GPi-DBS on speech and dysarthria is rarely described in the literature. This might be due to disease progression, non-effectiveness of DBS or due to inadvertent spreading of the electrical current to the corticobulbar tract causing stimulation induced dysarthria. This highlights the importance of optimal lead placement, the possibility of horizontal steering of the electrical field by applying directional stimulation with segmented leads as well as the use of the lowest possible effective stimulation intensity.
In 2005,
twork for
herapy in
are
pilepsies (NETRE)-was initiated in order to share treatment experiences among clinicians in patients with rare epilepsies. Here we describe the structure of the ...rapidly growing NETRE and summarize some of the findings of the last 15 years.
NETRE is organized in distinct groups (currently >270). Starting point is always a patient with a rare epilepsy/ epileptic disorder. This creates a new group, and next, a medical coordinator is appointed. The exchange of experiences is established using a data entry form, which the coordinator sends to colleagues. The primary aim is to exchange experiences (retrospectively, anonymously, MRI results also non-anonymously) of the epilepsy treatment as well as on clinical presentation and comorbidities NETRE is neither financed nor sponsored.
Some of the relevant results: (1) first description of FIRES as a new epilepsy syndrome and its further investigation, (2) in
, the assignment to gain- vs. loss-of-function mutations has a major impact on clinical decisions to use or avoid treatment with sodium channel blockers, (3) the important aspect of avoiding overtreatment in
patients, due to loss of effects of anticonvulsants after 12 months, (4) pathognomonic MRI findings in
patients, (5) the first description of pathognomonic chewing-induced seizures in
patients, and the therapeutic effect of statins as anticonvulsant in these patients, (6) the phenomenon of another reflex epilepsy-bathing epilepsy associated with a
mutation. Of special interest is also a NETRE group following twins with genetic and/or structural epilepsies including vanishing-twin-syndrome and twin-twin-transfusion syndrome) = "Early Neuroimpaired Twin Entity" (ENITE).
NETRE enables clinicians to quickly exchange information on therapeutic experiences in rare diseases with colleagues at an international level. For both parents and clinicians/scientist this international exchange is both reassuring and helpful. In collaboration with other groups, personalized therapeutic approaches are sought, but the present limitations of currently available therapies are also highlighted. Presently, the PATRE Project (PATient based phenotyping and evaluation of therapy for Rare Epilepsies) is commencing, in which information on therapies will be obtained directly from patients and their caregivers.
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