Search

Aim: To assess the relationship of surface area of the cerebral cortex to intracranial volume (ICV) in syndromic craniosynostosis., Method: Records of 140 patients (64 males, 76 females; mean age 8y 6mo [SD 5y 6mo], range 1y 2mo-24y 2mo) with syndromic craniosynostosis were reviewed to include clinical and imaging data. Two hundred and three total magnetic resonance imaging (MRI) scans were evaluated in this study (148 patients with fibroblast growth factor receptor [FGFR], 19 patients with TWIST1, and 36 controls). MRIs were processed via FreeSurfer pipeline to determine total ICV and cortical surface area (CSA). Scaling coefficients were calculated from log-transformed data via mixed regression to account for multiple measurements, sex, syndrome, and age. Educational outcomes were reported by syndrome., Results: Mean ICV was greater in patients with FGFR (1519cm 3 , SD 269cm 3 , p=0.016) than in patients with TWIST1 (1304cm 3 , SD 145cm 3 ) or controls (1405cm 3 , SD 158cm 3 ). CSA was related to ICV by a scaling law with an exponent of 0.68 (95% confidence interval [CI] 0.61-0.76) in patients with FGFR compared to 0.81 (95% CI 0.50-1.12) in patients with TWIST1 and 0.77 (95% CI 0.61-0.93) in controls. Lobar analysis revealed reduced scaling in the parietal (0.50, 95% CI 0.42-0.59) and occipital (0.67, 95% CI 0.54-0.80) lobes of patients with FGFR compared with controls. Modified learning environments were needed more often in patients with FGFR., Interpretation: Despite adequate ICV in FGFR-mediated craniosynostosis, CSA development is reduced, indicating maldevelopment, particularly in parietal and occipital lobes. Modified education is also more common in patients with FGFR., (© 2021 The Authors. Developmental Medicine & Child Neurology published by John Wiley & Sons Ltd on behalf of Mac Keith Press.)

Introduction: Neurodevelopmental delay is more common in children born with congenital heart defects (CHD), even with optimal perinatal and peri-operative care. It is hypothesized that fetuses with CHD are prone to neurological impairment in utero due to their cardiac defect, possibly leading to delayed cortical development., Methods: Cerebral cortical maturation was assessed with advanced neurosonographic examinations every 4 weeks in fetuses with CHD and compared to control fetuses. Five different primary fissures and four areas were scored (ranging 0-5) by blinded examiners using a cortical maturation scheme., Results: Cortical staging was assessed in 574 ultrasound examinations in 85 CHD fetuses and 61 controls. Small differences in grading were seen in Sylvian and cingulate fissures. (Sylvian fissure: -0.12 grade, 95% CI (-0.23; -0.01) p = 0.05, cingulate fissure: -0.24 grade, 95% CI (-0.38; -0.10) p = <0.001. Other cortical areas showed normal maturation as compared to control fetuses., Conclusion: Small differences were seen in three of the nine analyzed cortical areas in CHD fetuses, in contrast to previous reports on progressive third-trimester delay. The clinical implications of the small differences however, remain unknown., (© 2021 The Authors. Prenatal Diagnosis published by John Wiley & Sons Ltd.)

Malformations of cortical development (MCD) represent a group of rare diseases with severe clinical presentation as epileptic and pharmacoresistant encephalopathies. Morphological studies in tissue from MCD patients have revealed reduced GABAergic efficacy and increased intracellular chloride concentration in neuronal cells as important pathophysiological mechanisms in MCD. Also, in various animal models, alterations of GABAergic inhibition have been postulated as a predominant factor contributing to perilesional hyperexcitability. Along with this line, the NKCC1 inhibitor bumetanide has been postulated as a potential drug for treatment of epilepsy, mediating its antiepileptic effect by reduction of the intracellular chloride and increased inhibitory efficacy of GABAergic transmission. In the present study, we focused on the focal freeze-lesion model of MCD to compare antiepileptic drugs with distinct mechanisms of action, including NKCC1 inhibition by bumetanide. For this purpose, we combined electrophysiological and optical methods in slice preparations and assessed the properties of seizure like events (SLE) induced by 4-aminopyridine. In freeze-lesioned but not control slices, SLE onset was confined to the perilesional area, confirming that this region is hyperexcitable and likely triggers pathological activity. Bumetanide selectively reduced epileptic activity in lesion-containing slices but not in slices from sham-treated control rats. Moreover, bumetanide caused a shift in the SLE onset site away from the perilesional area. In contrast, effects of other antiepileptic drugs including carbamazepine, lacosamide, acezatolamide and zonisamide occurred mostly independently of the lesion and did not result in a shift of the onset region. Our work adds evidence for the functional relevance of chloride homeostasis in the pathophysiology of microgyrus formation as represented in the focal freeze-lesion model. Further studies in different MCD models and human tissue will be required to validate the effects across different MCD subtypes and species and to assess the translational value of our findings., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Focal cortical dysplasia (FCD) and hemimegalencephaly (HME) are related malformations with shared etiologies. We report three patients with a spectrum of cortical malformations associated with pathogenic brain-specific somatic Ras homolog enriched in brain (RHEB) variants. The somatic variant load directly correlated with the size of the malformation, with upregulated mTOR activity confirmed in dysplastic tissues. Laser capture microdissection showed enrichment of RHEB variants in dysmorphic neurons and balloon cells. Our findings support the role of RHEB in a spectrum of cortical malformations confirming that FCD and HME represent a disease continuum, with the extent of dysplastic brain directly correlated with the somatic variant load., (© 2021 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

Abnormal levels of fibroblast growth factors (FGFs) and FGF receptors (FGFRs) have been detected in various neurological disorders. The potent impact of FGF-FGFR in multiple embryonic developmental processes makes it challenging to elucidate their roles in postmitotic neurons. Taking an alternative approach to examine the impact of aberrant FGFR function on glutamatergic neurons, we generated a FGFR gain-of-function (GOF) transgenic mouse, which expresses constitutively activated FGFR3 (FGFR3 K650E ) in postmitotic glutamatergic neurons. We found that GOF disrupts mitosis of radial-glia neural progenitors (RGCs), inside-out radial migration of post-mitotic glutamatergic neurons, and axonal tract projections. In particular, late-born CUX1-positive neurons are widely dispersed throughout the GOF cortex. Such a cortical migration deficit is likely caused, at least in part, by a significant reduction of the radial processes projecting from RGCs. RNA-sequencing analysis of the GOF embryonic cortex reveals significant alterations in several pathways involved in cell cycle regulation and axonal pathfinding. Collectively, our data suggest that FGFR3 GOF in postmitotic neurons not only alters axonal growth of postmitotic neurons but also impairs RGC neurogenesis and radial glia processes.

By using the Cre-mediated genetic switch technology, we were able to successfully generate a conditional knock-in mouse, bearing the KIF2A p.His321Asp missense point variant, identified in a subject with malformations of cortical development. These mice present with neuroanatomical anomalies and microcephaly associated with behavioral deficiencies and susceptibility to epilepsy, correlating with the described human phenotype. Using the flexibility of this model, we investigated RosaCre-, NestinCre- and NexCre-driven expression of the mutation to dissect the pathophysiological mechanisms underlying neurodevelopmental cortical abnormalities. We show that the expression of the p.His321Asp pathogenic variant increases apoptosis and causes abnormal multipolar to bipolar transition in newborn neurons, providing therefore insights to better understand cortical organization and brain growth defects that characterize KIF2A-related human disorders. We further demonstrate that the observed cellular phenotypes are likely to be linked to deficiency in the microtubule depolymerizing function of KIF2A., (© The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Aim: To evaluate gross motor function and associated factors in children with congenital Zika syndrome (CZS)., Method: Fifty-nine children (30 males, 29 females) with CZS at a mean (SD) age of 14.7 (3.9), months (range 5-29mo) were evaluated using the Gross Motor Function Measure (GMFM) and classified according to the Gross Motor Function Classification System (GMFCS). Neurological damage was evaluated by neuroimaging. The mothers' sociodemographic characteristics and general data on the children were obtained from interviews with the mothers and from the children's medical records. Correlational and multiple regression analyses were performed to identify factors associated with these children's motor function., Results: In 81% of the children, motor function impairment was severe, classified as GMFCS level V. The overall GMFM score ranged from 5 to 210 (median 18; interquartile range 11), with only four children receiving scores in the D and E dimensions. The factors found to affect motor function were the presence of severe malformations of cortical development and small head circumference at birth., Interpretation: Although motor impairment may be mild in some children, it is generally severe. Severe malformations of cortical development and small head circumference at birth were factors associated with poorer motor function, reflecting the greater severity of brain damage., What This Paper Adds: Motor impairment is severe in most children with congenital Zika syndrome (CZS). Motor skills are adequate or close to adequate for age in 7% of children with CZS. Severe malformations of cortical development are associated with poor motor control. Small head circumference at birth is also associated with poor motor control., (© 2019 Mac Keith Press.)

Background: Type IIIb dysplasia is a subtype of focal cortical dysplasia associated with a tumor, most frequently with gangliogliomas then with dysembryoplastic neuroepithelial tumors (DNETs). Their preoperative diagnosis often remains equivocal since specific features are missing. The functional results (i.e., seizure free) is good with 81%-87% of Engel Ia at 5-year follow-up., Case Description: A 4-year-old boy presented with a 1-year history of severe, invalidating, drug-resistant epilepsy. Imaging workup demonstrated a huge left limbic lesion, of which diagnosis remained speculative. Because of worsening neurological status, resective surgery was recommended after multidisciplinary discussion. The resection was performed through left transtemporal approach under neuronavigation (C.R.). Postoperative magnetic resonance imaging assessed uncomplicated near-total resection. Histopathological analysis showed combined features of a DNET of nonspecific type and a focal cortical dysplasia., Conclusion: We describe a rare condition of type IIIb dysplasia combining a focal cortical dysplasia with a DNET. Preoperative diagnosis of the lesion was of utmost difficultly, thereby rendering mandatory a thorough histopathological examination of resected specimen in the vast majority of cases. Increased recognition of the condition brings up the hypothesis of a genetic continuum or linkage between the 2 conditions. Functional results on seizure activity after ablative surgery are good and maximal safe resection should be the goal., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Our objective is to examine the layer and spectrotemporal architecture and laminar distribution of high-frequency oscillations (HFOs) in a neonatal freeze lesion model of focal cortical dysplasia (FCD) associated with a high prevalence of spontaneous spike-wave discharges (SWDs). Electrophysiological recording of local field potentials (LFPs) in control and freeze lesion animals were obtained with linear micro-electrode arrays to detect presence of HFOs as compared to changes in spectral power, signal coherence, and single-unit distributions during "hyper-excitable" epochs of anesthesia-induced burst-suppression (B-S). Result were compared to HFOs observed during spontaneous SWDs in animals during sleep. Micro-electrode array recordings from the malformed cortex indicated significant increases in the presence of HFOs above 100 Hz and associated increases in spectral power and altered LFP coherence of recorded signals across cortical lamina of freeze-lesioned animals with spontaneous bursts of high-frequency activity, confined predominately to granular and supragranular layers. Spike sorting of well-isolated single-units recorded from freeze-lesioned cortex indicated an increase in putative excitatory cell activity in the outer cortical layers that showed only a weak association with HFOs while deeper inhibitory units were strongly phase-locked to high-frequency ripple (HFR) oscillations (300-800 Hz). Both SWDs and B-S show increases in HFR activity that were phase-locked to the high-frequency spike pattern occurring at the trough of low frequency oscillations. The spontaneous cyclic spiking of cortical inhibitory cells appears to be the driving substrate behind the HFO patterns associated with SWDs and a hyperexcitable supragranular layer near the malformed cortex may play a key role in epileptogenesis in our model. These data, derived from a mouse model with a distinct focal cortical malformation, support recent clinical data that HFOs, particularly fast ripples, is a biomarker to help define the cortical seizure zone, and provide limited insights toward understanding cellular level changes underlying the HFOs.

Background: Prenatal infection is a substantial risk factor for neurodevelopmental disorders such as autism in offspring. We have previously reported that influenza vaccination (VAC) during early pregnancy contributes to neurogenesis and behavioral function in offspring., Results: Here, we probe the efficacy of VAC pretreatment on autism-like behaviors in a lipopolysaccharide (LPS)-induced maternal immune activation (MIA) mouse model. We show that VAC improves abnormal fetal brain cytoarchitecture and lamination, an effect associated with promotion of intermediate progenitor cell differentiation in MIA fetal brain. These beneficial effects are sufficient to prevent social deficits in adult MIA offspring. Furthermore, whole-genome analysis suggests a strong interaction between Ikzf1 (IKAROS family zinc-finger 1) and neuronal differentiation. Intriguingly, VAC rescues excessive microglial Ikzf1 expression and attenuates microglial inflammatory responses in the MIA fetal brain., Conclusions: Our study implies that a preprocessed influenza vaccination prevents maternal bacterial infection from causing neocortical lamination impairments and autism-related behaviors in offspring.

Background: Catastrophic epilepsy results in severe neurodevelopmental delay in infants because of frequent and/or long seizures. Therefore, consideration of early epilepsy surgery is essential for neurodevelopmental outcome. Once an infant with catastrophic seizures is identified as a surgical candidate, it is important that the surgical plan be carefully defined based on detailed presurgical evidence to minimize surgical complications in this age group., Case Description: We present 2 infants with catastrophic epilepsy, epileptic spasms, and bihemispheric electroencephalographic abnormalities who underwent one-stage disconnection surgery based on a sound hypothesis of the epileptogenic zone. Each patient underwent an extensive noninvasive presurgical investigation followed by stereotactic disconnection leucotomy in a single stage. After the 2 children were followed for 24-36 months. A seizure reduction by at least 90% (Engel class I) was achieved in both cases with subsequent improvement in neurodevelopmental progress. There were no perioperative complications. Both patients had widespread cortical dysplasia on pathologic evaluation., Conclusions: Careful consideration of the noninvasive presurgical workup can identify focal onset even in the presence of catastrophic epilepsy with widespread bilateral abnormalities. Single-stage lobar leucotomy for disconnection of the epileptogenic zone can lead to excellent outcome in these patients., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: Epilepsy is a common neurologic disorder resulting in spontaneous, recurrent seizures. About 30-40% of patients are not responsive to pharmacologic therapies. This may be due to the differences between individual patients such as etiology, underlying pathophysiology, and seizure focus, and it highlights the importance of new drug discovery and testing in this field. Our goal was to determine the efficacy of lacosamide (LCM), a drug approved for the treatment of focal seizures, in a model of generalized epilepsy with cortical dysplasia (CD). We sought to compare LCM to levetiracetam (LEV), a drug that is currently used for the treatment of both partial and generalized epilepsy and to test its proficiency., Methods: Pregnant rats were irradiated to produce pups with malformed cortices in a model of CD, which will be referred to as the "first hit." Adult animals, developed normally (NL) and irradiated (XRT), were surgically implanted with electroencephalography (EEG) electrodes. Baseline EEG was recorded on all rats prior to pretreatments with either LCM, LEV, or placebo (PBO). After 30 min, all rats were injected with a subconvulsive dose of pentylenetetrazole (PTZ), a γ-aminobutyric acid receptor A (GABA A ) antagonist used to provoke generalized seizures as a "second hit.", Results: LCM and LEV were both effective against seizures induced by PTZ. XRT rats had a higher seizure incidence with longer and more severe seizures than NL rats. Seizure duration was decreased with both LCM and LEV in all animals. In XRT rats, there was a significant reduction in acute seizure incidence and severity with both LCM and LEV after PTZ injection., Significance: Our results suggest that LCM could be used as a potential treatment option for generalized epilepsy with CD as the underlying pathology., (Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.)

Background and Purpose: Brain AVM, cerebral abscess, and ischemic stroke are among the well known neurologic manifestations of hereditary hemorrhagic telangiectasia. However, recently reported data suggest an additional association with malformations of cortical development. The purpose of this study was to determine the prevalence of malformations of cortical development in a population of pediatric patients with hereditary hemorrhagic telangiectasia., Materials and Methods: A retrospective review of brain MRIs from 116 pediatric patients was performed. Each patient was referred from our institution's Hereditary Hemorrhagic Telangiectasia Clinic. Each MRI included a 3D sequence, most frequently MPRAGE. The 3D sequence was evaluated by a neuroradiology fellow, with specific attention to the presence or absence of malformations of cortical development. Positive studies were subsequently reviewed by 2 attending neuroradiologists, who rendered a final diagnosis., Results: Fourteen of 116 (12.1%) patients were found to have a malformation of cortical development. Among these 14, there were 12 cases of polymicrogyria and 2 cases of bifrontal periventricular nodular heterotopia., Conclusions: Pediatric patients with hereditary hemorrhagic telangiectasia have a relatively high prevalence of malformations of cortical development, typically perisylvian polymicrogyria., (© 2017 by American Journal of Neuroradiology.)

Focal cortical dysplasia (FCD) is one of the most important causes of drug-resistant epilepsy in paediatric patients, particularly in those below the age of 3. Even though over 40 years have passed since the first description of the entity by Taylor, the exact mechanisms causing these cortical abnormalities remain unelucidated. In this review, we summarise the current knowledge on clinical and histopathological aspects, taking into account the new classification system proposed by the International League Against Epilepsy. We focus on the clinicopathological associations and differences in post-surgical outcome among FCD subtypes, in particular isolated FCD vs. FCD associated with principal lesions, which have not been summarised to date. We also recapitulate genetic studies, pointing to the possible mechanisms of the cortical dysregulation and drug resistance, and summarise novel factors which may contribute to epileptogenesis in FCD. Furthermore, we compare FCD type IIB (FCDIIB) with brain tumours found in a neurocutaneous disorder, tuberous sclerosis, as we evaluate the hypothesis that FCD IIB may be a local form of this disease.

Objective: To examine if mice with focal cortical dysplasia (FCD) develop spontaneous epileptic seizures and, if so, determine the key electroencephalography (EEG) features., Methods: Unilateral single freeze lesions to the S1 region (SFLS1R) were made in postnatal day 0-1 pups to induce a neocortical microgyrus in the right cortical hemisphere. Continuous 24-h recordings with intracranial EEG electrodes and behavioral tests were performed in adult SFLS1R and sham-control mice to assess neurologic status., Results: A high percentage of adult SFLS1R animals (89%, 40/45) exhibited at least one or more spontaneous nonconvulsive seizure events over the course of 24 h. Of these animals, 60% (27/45) presented with a chronic seizure state that was persistent throughout the recording session, consisting of bursts of rhythmic high-amplitude spike-wave activities and primarily occurring during periods of slow-wave sleep. In comparison, none of the control, age-matched, mice (0/12) developed seizures. The epileptic discharge pattern closely resembled a pattern of continuous spike-waves during slow-wave sleep (CSWS) of the human syndrome described as an electrical status epilepticus during slow-wave sleep (ESES). Key findings in the SFLS1R model indicated that the observed CSWS (1) were more prevalent in female (18/23) versus male (9/22, p < 0.05), (2) were strongest in the right S1 region although generalized to other brain regions, (3) were associated with significant cognitive and behavioral deficits, (4) were temporarily alleviated by ethosuximide treatment or optogenetic activation of cortical γ-aminobutyric acid (GABA)ergic neurons, and (5) theta and alpha band rhythms may play a key role in the generalization of spike-wave activities., Significance: This is the first report of an in vivo animal FCD model that induces chronic spontaneous electrographic brain seizures. Further characterization of the abnormal oscillations in this mouse model may lead to a better understanding of the mechanisms of CSWS/ESES., (Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.)

Hyaline protoplasmic astrocytopathy is a rare disorder marked by an accumulation of protein material in the cytoplasm of astrocytic cells, mostly in the cortex. The finding has been described in Aicardi syndrome (agenesis of the corpus callosum, chorioretinal lacunae and infantile spasms) as well as in patients with pharmacoresistant epilepsy and in association with focal cortical dysplasia, polymicrogyria and nodular heterotopia. This report describes the first case of this entity described in a patient with tuberous sclerosis. The patient was a 3-year-old boy who presented at age 2months with medically intractable seizures. Has mother has a tuberous sclerosis 2 (TSC 2) gene abnormality and a diagnosis of tuberous sclerosis. On imaging, he was noted to have multiple lesions in the left parietal and temporal lobes consistent with focal cortical dysplasia and a subependymal nodule. He additionally had two hypopigmented lesions on the skin. He underwent resection of the left parietal lobe 32months after seizure onset. Histopathologic examination showed eosinophilic cytoplasmic inclusions within astrocytes in the cortex and superficial white matter focally accompanied by a disordered cortical architecture with dysmorphic neurons and balloon cells, consistent with focal cortical dysplasia classified as type IIb according to International League Against Epilepsy classification criteria (ILAE type IIb). At the time of most recent follow-up, 93months postoperatively, he is still experiencing seizures with overall worthwhile improvement while on seizure medication., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Introduction: Resective epilepsy surgery is an established treatment option in patients with pharmacoresistant, lesion related epilepsy. Yet, if the presurgical work-up proves multi-focal organization of the epileptogenic zone, or the area of intended resection is close to eloquent brain areas, patients may decide against resections because of an unfavorable risk-benefit-ratio. We assess if lesion guided cortical stereotactic radiofrequency thermocoagulation (L-RFTC) is a potential surgical alternative in these patients., Methods: We performed seven procedures of L-RFTC. Three patients had monofocal epilepsy arising close to eloquent structures; in four, invasive pre-surgical workup documented monofocal seizure onset but strong interictal epileptic activity also independent and distant from the seizure onset zone. L-RFTC was restricted to the lesional area (=seizure onset site)., Results: 12 to 37 months after RFTC worthwhile seizure improvement was achieved in 6 patients. One patient became seizure free following complete coagulation of a focal cortical dysplasia, two had had 1-2 auras under tapered but not under continued medication. In one patient only subclinical seizures persisted. In one patient hypermotor seizures were transformed into milder short tonic seizures and another one had a seizure reduction by 50%. Only one patient did not profit at all. One patient developed a persisting neurological deficit., Significance: In patients with complex epileptogenic zones L-RFTC can lead to worthwhile seizure reduction. This qualifies this procedure as a palliative surgical technique with potential good risk-benefit ratio. In patients with small focal cortical dysplasias L-RFTC may even allow minimal-invasive surgery with curative intention., (Copyright © 2016 Elsevier B.V. All rights reserved.)

We report a rare case of a 22-year-old woman with biopsy-proven pigmented ganglioglioma. The patient initially underwent a right temporal lobectomy for intractable seizures at the age of 9 and remained seizure free for several years but subsequently developed complex partial seizures. Due to enhancement of a left mesial occipital lesion on preoperative MRI of the brain, the patient underwent a left subdural electrode placement and simultaneous biopsy of the left mesial occipital lesion. Biopsy results revealed a rare pigmented ganglioglioma, World Health Organization Grade I. The seizure focus was identified in the left mesial occipital lobe and the patient underwent tumor resection. An extensive literature search revealed that our patient is the fourth case of pigmented ganglioglioma described in the literature and was positive for BRAF V600E mutation by molecular studies., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Introduction: Epilepsy surgery is increasingly used to treat children with medically intractable epilepsy. This study investigates the aetiology and seizure outcome in Danish children operated between 1996 and 2010., Methods: Retrospectively collected data on structural magnetic resonance imaging (MRI) diagnoses, surgical procedures and seizure outcomes classified according to the Engel Classification were used. Changes over time grouped as 1996-2000, 2001-2005 and 2006-2010 were analysed., Results: A total of 95 children underwent epilepsy surgery. Sixty-three operations were performed in Denmark and 50 abroad. In all, 14 children needed reoperation. The median follow-up period was four years. At the latest follow-up, Engel class I (indicating no disabling seizures) was found in 67% of the patients. Cortical dysplasia, mesial temporal sclerosis and tumour were the most common MRI findings. The percentage of tumours operated decreased over time, and frontal lobe resections increased. In the 2006-2010 period, resections with normal MRI were performed, resulting in a less favourable Engel outcome. Persistent, unexpected complications were seen in three of 113 operations., Conclusions: The majority of children who undergo epilepsy surgery have a good, worthwhile seizure outcome. The seizure outcome for Danish children corresponds to that of other epilepsy surgery centres. The clinical criteria for selection of patients changed over time., Funding: none., Trial Registration: The Danish Data Protection Agency approved the project with record number: 2013-41-2459.

Purpose: To examine the cognition, spontaneous epilepsy, and electroencephalography (EEG) characteristics of rats with malformations of cortical development (MCD) and their use as an animal model for investigating the pathogenesis of intractable epilepsy and screening novel antiepileptic drugs., Methods: An epileptic rat model of MCD was established with the F1 generation of pregnant rats after X-irradiation with 175 cGy (Group L), 195 cGy (Group M), or 215 cGy (Group H). Long-term video-EEG monitoring was used to record the seizures in the rats with MCD. Cognition was assessed with the Morris water maze. The EEGs were recorded and analyzed in the frontal and parietal lobes and hippocampi of adult rats. Finally, the brain tissues were processed for Nissl staining., Results: The model groups exhibited markedly prolonged escape latencies and distinct decrements in the percent distance traveled in the target quadrant and platform-crossing frequency. These findings were dose-dependent. Frequent interictal epileptiform discharges were observed in the frontal and parietal lobes and hippocampi of adult rats, and their incidences were markedly higher in the model groups compared with that in the normal controls, with Group M having the highest incidence. Spontaneous seizures were observed in the model groups (mean incidence, 46.7%). The daily mean frequency of seizures and the incidence of spontaneous seizures were highest in Group M. Nissl staining revealed a dose-dependent pattern of hippocampal abnormalities, cortical and subcortical nodular heterotopia, and callosal agenesis in the model groups., Conclusion: The 195 cGy dose was most appropriate for establishing an epileptic model of MCD with X-irradiation., (Copyright © 2015 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.)

One of the most prominent features of the cerebral cortex of higher mammals is the presence of gyri. Because malformations of the cortical gyri are associated with severe disability in brain function, the mechanisms underlying malformations of the cortical gyri have been of great interest. Combining gyrencephalic carnivore ferrets and genetic manipulations using in utero electroporation, here we successfully recapitulated the cortical phenotypes of thanatophoric dysplasia (TD) by expressing fibroblast growth factor 8 in the ferret cerebral cortex. Strikingly, in contrast to TD mice, our TD ferret model showed not only megalencephaly but also polymicrogyria. We further uncovered that outer radial glial cells (oRGs) and intermediate progenitor cells (IPs) were markedly increased. Because it has been proposed that increased oRGs and/or IPs resulted in the appearance of cortical gyri during evolution, it seemed possible that increased oRGs and IPs underlie the pathogenesis of polymicrogyria. Our findings should help shed light on the molecular mechanisms underlying the formation and malformation of cortical gyri in higher mammals.

Pediatric epilepsy has a wide variety of etiology and severity. A recent epidemiological study suggested that surgery might be indicated in as many as 5% of the pediatric epilepsy population. Now, we know that effective epilepsy surgery can result in seizure freedom and improvement of psychomotor development. Seizure control is the most effective way to improve patients neurologically and psychologically. In this review, we look over the recent evidence related to pediatric epilepsy surgery, and try to establish the optimal surgical timing for patients with intractable epilepsy. Appropriate surgical timing depends on the etiology and natural history of the epilepsy to be treated. The most common etiology of pediatric intractable epilepsy patients is malformation of cortical development (MCD) and early surgery is recommended for them. Patients operated on earlier than 12 months of age tended to improve their psychomotor development compared to those operated on later. Recent progress in neuroimaging and electrophysiological studies provide the possibility of very early diagnosis and comprehensive surgical management even at an age before 12 months. Epilepsy surgery is the only solution for patients with MCD or other congenital diseases associated with intractable epilepsy, therefore physicians should aim at an early and precise diagnosis and predicting the future damage, consider a surgical solution within an optimal timing.

Developmental cortical malformations are associated with a high incidence of drug-resistant epilepsy. The underlying epileptogenic mechanisms, however, are poorly understood. In rodents, cortical malformations can be modeled using neonatal freeze-lesion (FL), which has been shown to cause in vitro cortical hyperexcitability. Here, we investigated the therapeutic potential of gabapentin, a clinically used anticonvulsant and analgesic, in preventing FL-induced in vitro and in vivo hyperexcitability. Gabapentin has been shown to disrupt the interaction of thrombospondin (TSP) with α2δ-1, an auxiliary calcium channel subunit. TSP/α2δ-1 signaling has been shown to drive the formation of excitatory synapses during cortical development and following injury. Gabapentin has been reported to have neuroprotective and anti-epileptogenic effects in other models associated with increased TSP expression and reactive astrocytosis. We found that both TSP and α2δ-1 were transiently upregulated following neonatal FL. We therefore designed a one-week GBP treatment paradigm to block TSP/α2δ-1 signaling during the period of their upregulation. GBP treatment prevented epileptiform activity following FL, as assessed by both glutamate biosensor imaging and field potential recording. GBP also attenuated FL-induced increases in mEPSC frequency at both P7 and 28. Additionally, GBP treated animals had decreased in vivo kainic acid (KA)-induced seizure activity. Taken together these results suggest gabapentin treatment immediately after FL can prevent the formation of a hyperexcitable network and may have therapeutic potential to minimize epileptogenic processes associated with developmental cortical malformations., (Copyright © 2014 Elsevier Inc. All rights reserved.)