Paroxysmal dystonia results from the loss of RIM4 in Purkinje cells.

Full-length RIM1 and 2 are key components of the presynaptic active zone that ubiquitously control excitatory and inhibitory neurotransmitter release. Here, we report that the function of the small RIM isoform RIM4, consisting of a single C2 domain, is strikingly different from that of the long isoforms. RIM4 is dispensable for neurotransmitter release but plays a postsynaptic, cell-type specific role in cerebellar Purkinje cells that is essential for normal motor function. In the absence of RIM4, Purkinje cell intrinsic firing is reduced and caffeine-sensitive, and dendritic integration of climbing fibre input is disturbed. Mice lacking RIM4, but not mice lacking RIM1/2, selectively in Purkinje cells exhibit a severe, hours-long paroxysmal dystonia. These episodes can also be induced by caffeine, ethanol or stress and closely resemble the deficits seen with mutations of the PNKD (paroxysmal non-kinesigenic dystonia) gene. Our data reveal essential postsynaptic functions of RIM proteins and show non-overlapping specialized functions of a small isoform despite high homology to a single domain in the full-length proteins.

Ganglioglioma cells potentiate neuronal network synchronicity and elicit burst discharges via released factors.

Gangliogliomas (GGs) represent the most frequent glioneuronal tumor entity associated with chronic recurrent seizures; rare anaplastic GGs variants retain the glioneuronal character. So far, key mechanisms triggering chronic hyperexcitability in the peritumoral area are unresolved. Based on a recent mouse model for anaplastic GG (BRAFV600E, mTOR activation and Trp53KO) we here assessed the influence of GG-secreted factors on non-neoplastic cells in-vitro. We generated conditioned medium (CM) from primary GG cell cultures to developing primary cortical neurons cultured on multielectrode-arrays and assessed their electrical activity in comparison to neurons incubated with naïve and neuronal CMs. Our results showed that the GG CM, while not affecting the mean firing rates of networks, strongly accelerated the formation of functional networks as indicated increased synchrony of firing and burst activity. Washing out the GG CM did not reverse these effects indicating an irreversible effect on the neuronal network. Mass spectrometry analysis of GG CM detected several enriched proteins associated with neurogenesis as well as gliogenesis, including Gap43, App, Apoe, S100a8, Tnc and Sod1. Concomitantly, immunocytochemical analysis of the neuronal cultures exposed to GG CM revealed abundant astrocytes suggesting that the GG-secreted factors induce astroglial proliferation. Pharmacological inhibition of astrocyte proliferation only partially reversed the accelerated network maturation in neuronal cultures exposed to GG CM indicating that the GG CM exerts a direct effect on the neuronal component. Taken together, we demonstrate that GG-derived paracrine signaling alone is sufficient to induce accelerated neuronal network development accompanied by astrocytic proliferation. Perspectively, a deeper understanding of factors involved may serve as the basis for future therapeutic approaches.

Neuropathological Insights into Unexpected Cognitive Decline in Epilepsy.

OBJECTIVE: Some patients unexpectedly display an unfavorable cognitive course after epilepsy surgery subsequent to any direct cognitive sequelae of the surgical treatment. Therefore, we conducted in-depth neuropathological examinations of resective specimens from corresponding patients to provide insights as to the underlying disease processes. METHODS: In this study, cases with significant cognitive deterioration following a previous postoperative assessment were extracted from the neuropsychological database of a longstanding epilepsy surgical program. An extensive reanalysis of available specimens was performed using current, state-of-the-art neuropathological examinations. Patients without cognitive deterioration but matched in regard to basic pathologies served as controls. RESULTS: Among the 355 operated patients who had undergone more than one postoperative neuropsychological examination, 30 (8%) showed significant cognitive decline in the period after surgery. Of the 24 patients with available specimens, 71% displayed further neuropathological changes in addition to the typical spectrum (ie, hippocampal sclerosis, focal cortical dysplasias, vascular lesions, and low-grade tumors), indicating (1) a secondary, putatively epilepsy-independent neurodegenerative disease process; (2) limbic inflammation; or (3) the enigmatic pathology pattern of "hippocampal gliosis" without segmental neurodegeneration. In the controls, the matched individual principal epilepsy-associated pathologies were not found in combination with the secondary pathology patterns of the study group. INTERPRETATION: Our findings indicate that patients who unexpectedly displayed unfavorable cognitive development beyond any direct surgical effects show rare and very particular pathogenetic causes or parallel, presumably independent, neurodegenerative alterations. A multicenter collection of such cases would be appreciated to discern presurgical biomarkers that help with surgical decision-making. ANN NEUROL 2023;93:536-550.

Evidence for interictal blood-brain barrier dysfunction in people with epilepsy.

OBJECTIVE: Interictal blood-brain barrier dysfunction in chronic epilepsy has been demonstrated in animal models and pathological specimens. Ictal blood-brain barrier dysfunction has been shown in humans in vivo using an experimental quantitative magnetic resonance imaging (MRI) protocol. Here, we hypothesized that interictal blood-brain barrier dysfunction is also present in people with drug-resistant epilepsy. METHODS: Thirty-nine people (21 females, mean age at MRI ± SD = 30 ± 8 years) with drug-resistant epilepsy were prospectively recruited and underwent interictal T1-relaxometry before and after administration of a paramagnetic contrast agent. Likewise, quantitative T1 was acquired in 29 people without epilepsy (12 females, age at MRI = 48 ± 18 years). Quantitative T1 difference maps were calculated and served as a surrogate imaging marker for blood-brain barrier dysfunction. Values of quantitative T1 difference maps inside hemispheres ipsilateral to the presumed seizure onset zone were then compared, on a voxelwise level and within presumed seizure onset zones, to the contralateral side of people with epilepsy and to people without epilepsy. RESULTS: Compared to the contralateral side, ipsilateral T1 difference values were significantly higher in white matter (corrected p < .05), gray matter (uncorrected p < .05), and presumed seizure onset zones (p = .04) in people with epilepsy. Compared to people without epilepsy, significantly higher T1 difference values were found in the anatomical vicinity of presumed seizure onset zones (p = .004). A subgroup of people with hippocampal sclerosis demonstrated significantly higher T1 difference values in the ipsilateral hippocampus and in regions strongly interconnected with the hippocampus compared to people without epilepsy (corrected p < .01). Finally, z-scores reflecting the deviation of T1 difference values within the presumed seizure onset zone were associated with verbal memory performance (p = .02) in people with temporal lobe epilepsy. SIGNIFICANCE: Our results indicate a blood-brain barrier dysfunction in drug-resistant epilepsy that is detectable interictally in vivo, anatomically related to the presumed seizure onset zone, and associated with cognitive deficits.

'Hippocampal innate inflammatory gliosis only' in pharmacoresistant temporal lobe epilepsy.

Drug-resistant mesial-temporal lobe epilepsy is a devastating disease with seizure onset in the hippocampal formation. A fraction of hippocampi samples from epilepsy-surgical procedures reveals a peculiar histological pattern referred to as 'gliosis only' with unresolved pathogenesis and enigmatic sequelae. Here, we hypothesize that 'gliosis only' represents a particular syndrome defined by distinct clinical and molecular characteristics. We curated an in-depth multiparameter integration of systematic clinical, neuropsychological as well as neuropathological analysis from a consecutive cohort of 627 patients, who underwent hippocampectomy for drug-resistant temporal lobe epilepsy. All patients underwent either classic anterior temporal lobectomy or selective amygdalohippocampectomy. On the basis of their neuropathological exam, patients with hippocampus sclerosis and 'gliosis only' were characterized and compared within the whole cohort and within a subset of matched pairs. Integrated transcriptional analysis was performed to address molecular differences between both groups. 'Gliosis only' revealed demographics, clinical and neuropsychological outcome fundamentally different from hippocampus sclerosis. 'Gliosis only' patients had a significantly later seizure onset (16.3 versus 12.2 years, P = 0.005) and worse neuropsychological outcome after surgery compared to patients with hippocampus sclerosis. Epilepsy was less amendable by surgery in 'gliosis only' patients, resulting in a significantly worse rate of seizure freedom after surgery in this subgroup (43% versus 68%, P = 0.0001, odds ratio = 2.8, confidence interval 1.7-4.7). This finding remained significant after multivariate and matched-pairs analysis. The 'gliosis only' group demonstrated pronounced astrogliosis and lack of significant neuronal degeneration in contrast to characteristic segmental neuron loss and fibrillary astrogliosis in hippocampus sclerosis. RNA-sequencing of gliosis only patients deciphered a distinct transcriptional programme that resembles an innate inflammatory response of reactive astrocytes. Our data indicate a new temporal lobe epilepsy syndrome for which we suggest the term 'Innate inflammatory gliosis only'. 'Innate inflammatory gliosis only' is characterized by a diffuse gliosis pattern lacking restricted hippocampal focality and is poorly controllable by surgery. Thus, 'innate inflammatory gliosis only' patients need to be clearly identified by presurgical examination paradigms of pharmacoresistant temporal lobe epilepsy patients; surgical treatment of this subgroup should be considered with great precaution. 'Innate inflammatory gliosis only' requires innovative pharmacotreatment strategies.

Temporal lobe epilepsy with GAD antibodies: neurons killed by T cells not by complement membrane attack complex.

Temporal lobe epilepsy (TLE) is one of the syndromes linked to antibodies against glutamic acid decarboxylase (GAD). It has been questioned whether 'limbic encephalitis with GAD antibodies' is a meaningful diagnostic entity. The immunopathogenesis of GAD-TLE has remained enigmatic. Improvement of immunological treatability is an urgent clinical concern. We retrospectively assessed the clinical, MRI and CSF course as well as brain tissue of 15 adult patients with GAD-TLE who underwent temporal lobe surgery. Brain tissue was studied by means of immunohistochemistry, multiplex fluorescent microscopy and transcriptomic analysis for inflammatory mediators and neuronal degeneration. In 10 patients, there was a period of mediotemporal swelling and T2 signal increase; in nine cases this occurred within the first 6 years after symptom onset. This resulted in unilateral or bilateral hippocampal sclerosis; three cases developed hippocampal sclerosis within the first 2 years. All CSF studies done within the first year (n = 6) revealed intrathecal synthesis of immunoglobulin G. Temporal lobe surgeries were done after a median disease duration of 9 years (range 3 weeks to 60 years). Only two patients became seizure-free. Brain parenchyma collected during surgery in the first 6 years revealed high numbers of plasma cells but no signs of antibody-mediated tissue damage. Even more dense was the infiltration by CD8+ cytotoxic T lymphocytes (CTLs) that were seen to locally proliferate. Further, a portion of these cells revealed an antigen-specific resident memory T cell phenotype. Finally, CTLs with cytotoxic granzyme B+ granules were also seen in microglial nodules and attached to neurons, suggesting a CTL-mediated destruction of these cells. With longer disease duration, the density of all lymphocytes decreased. Whole transcriptome analysis in early/active cases (but not in late/inactive stages) revealed 'T cell immunity' and 'Regulation of immune processes' as the largest overrepresented clusters. To a lesser extent, pathways associated with B cells and neuronal degeneration also showed increased representation. Surgically treated patients with GAD-TLE go through an early active inflammatory, 'encephalitic' stage (≤6 years) with CTL-mediated, antigen-driven neuronal loss and antibody-producing plasma cells but without signs of complement-mediated cell death. Subsequently, patients enter an apparently immunologically inactive or low-active stage with ongoing seizures, probably caused by the structural damage to the temporal lobe. 'Limbic encephalitis' with GAD antibodies should be subsumed under GAD-TLE. The early tissue damage explains why immunotherapy does not usually lead to freedom from seizures.

DNA methylation-based classification of central nervous system tumours.

Accurate pathological diagnosis is crucial for optimal management of patients with cancer. For the approximately 100 known tumour types of the central nervous system, standardization of the diagnostic process has been shown to be particularly challenging-with substantial inter-observer variability in the histopathological diagnosis of many tumour types. Here we present a comprehensive approach for the DNA methylation-based classification of central nervous system tumours across all entities and age groups, and demonstrate its application in a routine diagnostic setting. We show that the availability of this method may have a substantial impact on diagnostic precision compared to standard methods, resulting in a change of diagnosis in up to 12% of prospective cases. For broader accessibility, we have designed a free online classifier tool, the use of which does not require any additional onsite data processing. Our results provide a blueprint for the generation of machine-learning-based tumour classifiers across other cancer entities, with the potential to fundamentally transform tumour pathology.

A CRISPR-Cas9-engineered mouse model for GPI-anchor deficiency mirrors human phenotypes and exhibits hippocampal synaptic dysfunctions.

Pathogenic germline mutations in PIGV lead to glycosylphosphatidylinositol biosynthesis deficiency (GPIBD). Individuals with pathogenic biallelic mutations in genes of the glycosylphosphatidylinositol (GPI)-anchor pathway exhibit cognitive impairments, motor delay, and often epilepsy. Thus far, the pathophysiology underlying the disease remains unclear, and suitable rodent models that mirror all symptoms observed in human patients have not been available. Therefore, we used CRISPR-Cas9 to introduce the most prevalent hypomorphic missense mutation in European patients, Pigv:c.1022C > A (p.A341E), at a site that is conserved in mice. Mirroring the human pathology, mutant Pigv341E mice exhibited deficits in motor coordination, cognitive impairments, and alterations in sociability and sleep patterns, as well as increased seizure susceptibility. Furthermore, immunohistochemistry revealed reduced synaptophysin immunoreactivity in Pigv341E mice, and electrophysiology recordings showed decreased hippocampal synaptic transmission that could underlie impaired memory formation. In single-cell RNA sequencing, Pigv341E-hippocampal cells exhibited changes in gene expression, most prominently in a subtype of microglia and subicular neurons. A significant reduction in Abl1 transcript levels in several cell clusters suggested a link to the signaling pathway of GPI-anchored ephrins. We also observed elevated levels of Hdc transcripts, which might affect histamine metabolism with consequences for circadian rhythm. This mouse model will not only open the doors to further investigation into the pathophysiology of GPIBD, but will also deepen our understanding of the role of GPI-anchor-related pathways in brain development.

A novel geometry-based analysis of hippocampal morphometry in mesial temporal lobe epilepsy.

Hippocampal volumetry is an essential tool in researching and diagnosing mesial temporal lobe epilepsy (mTLE). However, it has a limited ability to detect subtle alterations in hippocampal morphometry. Here, we establish and apply a novel geometry-based tool that enables point-wise morphometric analysis based on an intrinsic coordinate system of the hippocampus. We hypothesized that this point-wise analysis uncovers structural alterations not measurable by volumetry, but associated with histological underpinnings and the neuropsychological profile of mTLE. We conducted a retrospective study in 204 individuals with mTLE and 57 age- and gender-matched healthy subjects. FreeSurfer-based segmentations of hippocampal subfields in 3T-MRI were subjected to a geometry-based analysis that resulted in a coordinate system of the hippocampal mid-surface and allowed for point-wise measurements of hippocampal thickness and other features. Using point-wise analysis, we found significantly lower thickness and higher FLAIR signal intensity in the entire affected hippocampus of individuals with hippocampal sclerosis (HS-mTLE). In the contralateral hippocampus of HS-mTLE and the affected hippocampus of MRI-negative mTLE, we observed significantly lower thickness in the presubiculum. Impaired verbal memory was associated with lower thickness in the left presubiculum. In HS-mTLE histological subtype 3, we observed higher curvature than in subtypes 1 and 2 (all p < .05). These findings could not be observed using conventional volumetry (Bonferroni-corrected p < .05). We show that point-wise measures of hippocampal morphometry can uncover structural alterations not measurable by volumetry while also reflecting histological underpinnings and verbal memory. This substantiates the prospect of their clinical application.

Neurochemical Profile of BRAFV600E/AktT308D/S473D Mouse Gangliogliomas Reveals Impaired GABAergic System Inhibition.

Gangliogliomas (GGs), composed of dysmorphic neurons and neoplastic astroglia, represent the most frequent tumor entity associated with chronic recurrent epileptic seizures. So far, a systematic analysis of potential differences in neurochemical profiles of dysmorphic tumoral neurons as well as neurons of the peritumoral microenvironment (PTME) was hampered by the inability to unequivocally differentiate between the distinct neuronal components in human GG biopsies. Here, we have applied a novel GG mouse model that allows to clearly resolve the neurochemical profiles of GG-intrinsic versus PTME neurons. For this purpose, glioneuronal tumors in mice were induced by intraventricular in utero electroporation (IUE) of piggyBac-based plasmids for BRAFV600E and activated Akt (AktT308D/S473D, further referred to as AktDD) and analyzed neurochemically by immunocytochemistry against specific marker proteins. IUE of BRAFV600E/AktDD in mice resulted in tumors with the morphological features of human GGs. Our immunocytochemical analysis revealed a strong reduction of GABAARα1 immunoreactivity in the tumor compared to the PTME. In contrast, the extent of NMDAR1 immunoreactivity in the tumor appeared comparable to the PTME. Interestingly, tumor cells maintained the potential to express both receptors. Fittingly, the abundance of the presynaptic vesicular neurotransmitter transporters VGLUT1 and VGAT was also decreased in the tumor. Additionally, the fraction of parvalbumin and somatostatin nonneoplastic interneurons was reduced. In conclusion, changes in the levels of key proteins in neurotransmitter signaling suggest a loss of synapses and may thereby lead to neuronal network alterations in mouse GGs.

Artificial intelligence for the detection of focal cortical dysplasia: Challenges in translating algorithms into clinical practice.

Focal cortical dysplasias (FCDs) are malformations of cortical development and one of the most common pathologies causing pharmacoresistant focal epilepsy. Resective neurosurgery yields high success rates, especially if the full extent of the lesion is correctly identified and completely removed. The visual assessment of magnetic resonance imaging does not pinpoint the FCD in 30%-50% of cases, and half of all patients with FCD are not amenable to epilepsy surgery, partly because the FCD could not be sufficiently localized. Computational approaches to FCD detection are an active area of research, benefitting from advancements in computer vision. Automatic FCD detection is a significant challenge and one of the first clinical grounds where the application of artificial intelligence may translate into an advance for patients' health. The emergence of new methods from the combination of health and computer sciences creates novel challenges. Imaging data need to be organized into structured, well-annotated datasets and combined with other clinical information, such as histopathological subtypes or neuroimaging characteristics. Algorithmic output, that is, model prediction, requires a technically correct evaluation with adequate metrics that are understandable and usable for clinicians. Publication of code and data is necessary to make research accessible and reproducible. This critical review introduces the field of automatic FCD detection, explaining underlying medical and technical concepts, highlighting its challenges and current limitations, and providing a perspective for a novel research environment.

The multifactorial etiology of cognitive deficits in epilepsy and the neuropathology of mesial temporal lobe epilepsy beyond hyperphosphorylated tau.

In response to the recent review by Zawar and Kapur on the overlap between mesial temporal lobe epilepsy (MTLE) and Alzheimer's disease (AD), we (1) underscore that the bidirectionality between epilepsy and dementia is of high interest, also from the epileptological perspective; (2) outline the multifactorial etiology of cognitive deficits in epilepsy; (3) emphasize that the most prevalent neuropathological findings in MTLE comprise hippocampal sclerosis, dysplastic lesions, and neurodevelopmental neoplasm; and (4) state that anti-seizure medication can also have adverse effects on cognition. We conclude that the neuropsychology and neuropathology of MTLE is actually more complex than implicated in the review by Zawar and Kapur. Their suggested model may be valid for a small specific subgroup of cases. However, more studies are needed to confirm the role of hyperphosphorylated tau in epilepsy patients with and without AD considering age and age at epilepsy onset as potential moderator variables.

Ste20-like Kinase Is Critical for Inhibitory Synapse Maintenance and Its Deficiency Confers a Developmental Dendritopathy.

The size and structure of the dendritic arbor play important roles in determining how synaptic inputs of neurons are converted to action potential output. The regulatory mechanisms governing the development of dendrites, however, are insufficiently understood. The evolutionary conserved Ste20/Hippo kinase pathway has been proposed to play an important role in regulating the formation and maintenance of dendritic architecture. A key element of this pathway, Ste20-like kinase (SLK), regulates cytoskeletal dynamics in non-neuronal cells and is strongly expressed throughout neuronal development. However, its function in neurons is unknown. We show that, during development of mouse cortical neurons, SLK has a surprisingly specific role for proper elaboration of higher, ≥ third-order dendrites both in male and in female mice. Moreover, we demonstrate that SLK is required to maintain excitation-inhibition balance. Specifically, SLK knockdown caused a selective loss of inhibitory synapses and functional inhibition after postnatal day 15, whereas excitatory neurotransmission was unaffected. Finally, we show that this mechanism may be relevant for human disease, as dysmorphic neurons within human cortical malformations revealed significant loss of SLK expression. Overall, the present data identify SLK as a key regulator of both dendritic complexity during development and inhibitory synapse maintenance.SIGNIFICANCE STATEMENT We show that dysmorphic neurons of human epileptogenic brain lesions have decreased levels of the Ste20-like kinase (SLK). Decreasing SLK expression in mouse neurons revealed that SLK has essential functions in forming the neuronal dendritic tree and in maintaining inhibitory connections with neighboring neurons.

Anaplastic ganglioglioma-A diagnosis comprising several distinct tumour types.

AIMS: Anaplastic ganglioglioma is a rare tumour, and diagnosis has been based on histological criteria. The 5th edition of the World Health Organization Classification of Tumours of the Central Nervous System (CNS WHO) does not list anaplastic ganglioglioma as a distinct diagnosis due to lack of molecular data in previous publications. We retrospectively compiled a cohort of 54 histologically diagnosed anaplastic gangliogliomas to explore whether the molecular profiles of these tumours represent a separate type or resolve into other entities. METHODS: Samples were subjected to histological review, desoxyribonucleic acid (DNA) methylation profiling and next-generation sequencing. Morphological and molecular data were summarised to an integrated diagnosis. RESULTS: The majority of tumours designated as anaplastic gangliogliomas resolved into other CNS WHO diagnoses, most commonly pleomorphic xanthoastrocytoma (16/54), glioblastoma, isocitrate dehydrogenase protein (IDH) wild type and diffuse paediatric-type high-grade glioma, H3 wild type and IDH wild type (11 and 2/54), followed by low-grade glial or glioneuronal tumours including pilocytic astrocytoma, dysembryoplastic neuroepithelial tumour and diffuse leptomeningeal glioneuronal tumour (5/54), IDH mutant astrocytoma (4/54) and others (6/54). A subset of tumours (10/54) was not assignable to a CNS WHO diagnosis, and common molecular profiles pointing to a separate entity were not evident. CONCLUSIONS: In summary, we show that tumours histologically diagnosed as anaplastic ganglioglioma comprise a wide spectrum of CNS WHO tumour types with different prognostic and therapeutic implications. We therefore suggest assigning this designation with caution and recommend comprehensive molecular workup.

CD8+ T-Lymphocyte-Driven Limbic Encephalitis Results in Temporal Lobe Epilepsy.

OBJECTIVE: Limbic encephalitis (LE) comprises a spectrum of inflammatory changes in affected brain structures including the presence of autoantibodies and lymphoid cells. However, the potential of distinct lymphocyte subsets alone to elicit key clinicopathological sequelae of LE potentially inducing temporal lobe epilepsy (TLE) with chronic spontaneous seizures and hippocampal sclerosis (HS) is unresolved. METHODS: Here, we scrutinized pathogenic consequences emerging from CD8+ T cells targeting hippocampal neurons by recombinant adeno-associated virus-mediated expression of the model-autoantigen ovalbumin (OVA) in CA1 neurons of OT-I/RAG1-/- mice (termed "OVA-CD8+ LE model"). RESULTS: Viral-mediated antigen transfer caused dense CD8+ T cell infiltrates confined to the hippocampal formation starting on day 5 after virus transduction. Flow cytometry indicated priming of CD8+ T cells in brain-draining lymph nodes preceding hippocampal invasion. At the acute model stage, the inflammatory process was accompanied by frequent seizure activity and impairment of hippocampal memory skills. Magnetic resonance imaging scans at day 7 of the OVA-CD8+ LE model revealed hippocampal edema and blood-brain barrier disruption that converted into atrophy until day 40. CD8+ T cells specifically targeted OVA-expressing, SIINFEKL-H-2Kb -positive CA1 neurons and caused segmental apoptotic neurodegeneration, astrogliosis, and microglial activation. At the chronic model stage, mice exhibited spontaneous recurrent seizures and persisting memory deficits, and the sclerotic hippocampus was populated with CD8+ T cells escorted by NK cells. INTERPRETATION: These data indicate that a CD8+ T-cell-initiated attack of distinct hippocampal neurons is sufficient to induce LE converting into TLE-HS. Intriguingly, the role of CD8+ T cells exceeds neurotoxic effects and points to their major pathogenic role in TLE following LE. ANN NEUROL 2021;89:666-685.

SCN1A overexpression, associated with a genomic region marked by a risk variant for a common epilepsy, raises seizure susceptibility.

Mesial temporal lobe epilepsy with hippocampal sclerosis and a history of febrile seizures is associated with common variation at rs7587026, located in the promoter region of SCN1A. We sought to explore possible underlying mechanisms. SCN1A expression was analysed in hippocampal biopsy specimens of individuals with mesial temporal lobe epilepsy with hippocampal sclerosis who underwent surgical treatment, and hippocampal neuronal cell loss was quantitatively assessed using immunohistochemistry. In healthy individuals, hippocampal volume was measured using MRI. Analyses were performed stratified by rs7587026 type. To study the functional consequences of increased SCN1A expression, we generated, using transposon-mediated bacterial artificial chromosome transgenesis, a zebrafish line expressing exogenous scn1a, and performed EEG analysis on larval optic tecta at 4 day post-fertilization. Finally, we used an in vitro promoter analysis to study whether the genetic motif containing rs7587026 influences promoter activity. Hippocampal SCN1A expression differed by rs7587026 genotype (Kruskal-Wallis test P = 0.004). Individuals homozygous for the minor allele showed significantly increased expression compared to those homozygous for the major allele (Dunn's test P = 0.003), and to heterozygotes (Dunn's test P = 0.035). No statistically significant differences in hippocampal neuronal cell loss were observed between the three genotypes. Among 597 healthy participants, individuals homozygous for the minor allele at rs7587026 displayed significantly reduced mean hippocampal volume compared to major allele homozygotes (Cohen's D = - 0.28, P = 0.02), and to heterozygotes (Cohen's D = - 0.36, P = 0.009). Compared to wild type, scn1lab-overexpressing zebrafish larvae exhibited more frequent spontaneous seizures [one-way ANOVA F(4,54) = 6.95 (P < 0.001)]. The number of EEG discharges correlated with the level of scn1lab overexpression [one-way ANOVA F(4,15) = 10.75 (P < 0.001]. Finally, we showed that a 50 bp promoter motif containing rs7587026 exerts a strong regulatory role on SCN1A expression, though we could not directly link this to rs7587026 itself. Our results develop the mechanistic link between rs7587026 and mesial temporal lobe epilepsy with hippocampal sclerosis and a history of febrile seizures. Furthermore, we propose that quantitative precision may be important when increasing SCN1A expression in current strategies aiming to treat seizures in conditions involving SCN1A haploinsufficiency, such as Dravet syndrome.

Preoperative and postoperative memory in epilepsy patients with 'gliosis only' versus hippocampal sclerosis: a matched case-control study.

BACKGROUND: Gliosis only (GO) and hippocampal sclerosis (HS) are distinct histopathological entities in mesial temporal lobe epilepsy. This study explores whether this distinction also exists on a functional level when evaluating pre- and postoperative memory. METHODS: Using a retrospective matched case-control study design, we analysed verbal and visual memory performance in 49 patients with GO and 49 patients with HS before and one year after elective surgery. RESULTS: Clinical differences were evident with a later age at seizure onset (18±12 vs 12±9 years) and fewer postoperative seizure-free patients in the GO group (63% vs 82%). Preoperatively, group and individual-level data demonstrated that memory impairments were less frequent, less severe and relatively non-specific in patients with GO compared with HS. Postoperatively, verbal memory declined in both groups, particularly after left-sided resections, with more significant losses in patients with GO. Factoring in floor effects, GO was also associated with more significant visual memory loss, particularly after left resections. CONCLUSIONS: Compared with HS, GO is characterised by (1) a later onset of epilepsy, (2) less pronounced and more non-specific memory impairments before surgery, (3) a less successful surgical outcome and (4) a more significant memory decline after surgery. Overall, our results regarding cognition provide further evidence that GO and HS are distinct clinical entities. Functional integrity of the hippocampus appears higher in GO, as indicated by a better preoperative memory performance and worse memory outcome after surgery. The different risk-benefit ratios should be considered during presurgical patient counselling.

Seizure underreporting in LGI1 and CASPR2 antibody encephalitis.

Patients with anti-leucine-rich glioma-inactivated 1 protein (LGI1) or anti-contactin-associated protein 2 (CASPR2) antibody encephalitis typically present with frequent epileptic seizures. The seizures generally respond well to immunosuppressive therapy, and the long-term seizure outcome seems to be favorable. Consequentially, diagnosing acute symptomatic seizures secondary to autoimmune encephalitis instead of autoimmune epilepsy was proposed. However, published data on long-term seizure outcomes in CASPR2 and LGI1 antibody encephalitis are mostly based on patient reports, and seizure underreporting is a recognized issue. Clinical records from our tertiary epilepsy center were screened retrospectively for patients with LGI1 and CASPR2 antibody encephalitis who reported seizure freedom for at least 3 months and received video-electroencephalography (EEG) for >24 h at follow-up visits. Twenty (LGI1, n = 15; CASPR2, n = 5) of 32 patients with LGI1 (n = 24) and CASPR2 (n = 8) antibody encephalitis fulfilled these criteria. We recorded focal aware and impaired awareness seizures in four of these patients (20%) with reported seizure-free intervals ranging from 3 to 27 months. Our results question the favorable seizure outcome in patients with CASPR2 and LGI1 antibody encephalitis and suggest that the proportion of patients who have persistent seizures may be greater. Our findings underline the importance of prolonged video-EEG telemetry in this population.

Elevated baseline C-reactive protein levels predict poor progression-free survival in sporadic vestibular schwannoma.

BACKGROUND: Recent investigations showed emerging evidence of the role of inflammation in the growth of sporadic vestibular schwannoma (VS). The present retrospective study investigated the impact of systemic inflammation on tumor progression using serum C-reactive protein (CRP) levels in a series of 87 surgically treated sporadic VS patients. METHODS: The optimal cut-off value for CRP was defined as 3.14 mg/dl according to the receiver operating characteristic curve (AUC: 0.70, 95% CI 0.47-0.92). Patient cohort was dichotomized into normal (n = 66; < 3.14 mg/dl) and high baseline (n = 21; ≥ 3.14 mg/dl) CRP groups. RESULTS: No significant differences in age, sex, comorbidities influencing the systemic inflammatory state, Karnofsky performance status (KPS), tumor size, extent of resection, or MIB-1 index were identified between the two groups defined by the baseline CRP levels. Univariable analysis demonstrated that a high CRP level (≥ 3.14 mg/dl) is significantly associated with a shortened progression-free survival (PFS) (hazard ratio (HR): 6.05, 95% CI 1.15-31.95, p = 0.03). Multivariable Cox regression analysis considering age, extent of resection, KPS, tumor size, and baseline CRP confirmed that an elevated CRP level (≥ 3.14 mg/dl) is an independent predictor of shortened PFS (HR: 7.20, 95% CI 1.08-48.14, p = 0.04). CONCLUSIONS: The baseline CRP level thus serves as an independent predictor of PFS. Further investigations of the role of inflammation and tumor inflammatory microenvironment in the prediction of prognosis in sporadic VS are needed.

Shape description and volumetry of hippocampus and amygdala in temporal lobe epilepsy - A beneficial combination with a clinical perspective.

Shape-based markers have entered the field of morphometric neuroimaging analysis as a second mainstay alongside conventional volumetric approaches. We aimed to assess the added value of shape description for the analysis of lesional and autoimmune temporal lobe epilepsy (TLE) focusing on hippocampus and amygdala. We retrospectively investigated MRI and clinical data from 65 patients with lesional TLE (hippocampal sclerosis (HS) and astrogliosis) and from 62 patients with limbic encephalitis (LE) with serologically proven autoantibodies. Surface reconstruction and volumetric segmentation were performed with FreeSurfer. For the shape analysis, we used BrainPrint, a tool that utilizes eigenvalues of the Laplace-Beltrami operator on triangular meshes to calculate intra-subject asymmetry. Psychometric tests of memory performance were ascertained, to evaluate clinical relevance of the shape descriptor. The potential benefit of shape in addition to volumetric information for classification was assessed by five-fold repeated cross validation and logistic regression. For the LE group, the best performing classification model consisted of a combination of volume and shape asymmetry (mean AUC = 0.728), the logistic regression model was significantly improved considering both modalities instead of just volume asymmetry. For lesional TLE, the best model only considered volumetric information (mean AUC = 0.867). Shape asymmetry of the hippocampus was largely associated with verbal memory performance only in LE patients (OR = 1.07, p = 0.02). For lesional TLE, shape description is robust, but redundant when compared to volumetric approaches. For LE, in contrast, shape asymmetry as a complementary modality significantly improves the detection of subtle morphometric changes and is further associated with memory performance, which underscores the clinical relevance of shape asymmetry as a novel imaging biomarker.