Form Of Intractable Epilepsy Research Articles

Beyond CBD: Inhibitory effects of lesser studied phytocannabinoids on human voltage-gated sodium channels.

Introduction: Cannabis contains cannabidiol (CBD), the main non-psychoactive phytocannabinoid, but also many other phytocannabinoids that have therapeutic potential in the treatment of epilepsy. Indeed, the phytocannabinoids cannabigerolic acid (CBGA), cannabidivarinic acid (CBDVA), cannabichromenic acid (CBCA) and cannabichromene (CBC) have recently been shown to have anti-convulsant effects in a mouse model of Dravet syndrome (DS), an intractable form of epilepsy. Recent studies demonstrate that CBD inhibits voltage-gated sodium channel function, however, whether these other anti-convulsant phytocannabinoids affect these classic epilepsy drug-targets is unknown. Voltage-gated sodium (NaV) channels play a pivotal role in initiation and propagation of the neuronal action potential and NaV1.1, NaV1.2, NaV1.6 and NaV1.7 are associated with the intractable epilepsies and pain conditions. Methods: In this study, using automated-planar patch-clamp technology, we assessed the profile of the phytocannabinoids CBGA, CBDVA, cannabigerol (CBG), CBCA and CBC against these human voltage-gated sodium channels subtypes expressed in mammalian cells and compared the effects to CBD. Results: CBD and CBGA inhibited peak current amplitude in the low micromolar range in a concentration-dependent manner, while CBG, CBCA and CBC revealed only modest inhibition for this subset of sodium channels. CBDVA inhibited NaV1.6 peak currents in the low micromolar range in a concentration-dependent fashion, while only exhibiting modest inhibitory effects on NaV1.1, NaV1.2, and NaV1.7 channels. CBD and CBGA non-selectively inhibited all channel subtypes examined, whereas CBDVA was selective for NaV1.6. In addition, to better understand the mechanism of this inhibition, we examined the biophysical properties of these channels in the presence of each cannabinoid. CBD reduced NaV1.1 and NaV1.7 channel availability by modulating the voltage-dependence of steady-state fast inactivation (SSFI, V0.5 inact), and for NaV1.7 channel conductance was reduced. CBGA also reduced NaV1.1 and NaV1.7 channel availability by shifting the voltage-dependence of activation (V0.5 act) to a more depolarized potential, and for NaV1.7 SSFI was shifted to a more hyperpolarized potential. CBDVA reduced channel availability by modifying conductance, SSFI and recovery from SSFI for all four channels, except for NaV1.2, where V0.5 inact was unaffected. Discussion: Collectively, these data advance our understanding of the molecular actions of lesser studied phytocannabinoids on voltage-gated sodium channel proteins.

The Clock gene regulates kainic acid-induced seizures through inhibiting ferroptosis in mice.

Temporal lobe epilepsy (TLE) is a common and intractable form of epilepsy. There is a strong need to better understand molecular events underlying TLE and to find novel therapeutic agents. Here we aimed to investigate the role of Clock and ferroptosis in regulating TLE. TLE model was established by treating mice with kainic acid (KA). Regulatory effects of the Clock gene on KA-induced seizures and ferroptosis were evaluated using Clock knockout (Clock-/-) mice. mRNA and protein levels were determined by quantitative real-time PCR and western blotting, respectively. Ferroptosis was assessed by measuring the levels of iron, GSH and ROS. Transcriptional regulation was studied using a combination of luciferase reporter, mobility shift and chromatin immunoprecipitation (ChIP) assays. We found that Clock ablation exacerbated KA-induced seizures in mice, accompanied by enhanced ferroptosis in the hippocampus. Clock ablation reduced the hippocampal expression of GPX4 and PPAR-γ, two ferroptosis-inhibitory factors, in mice and in N2a cells. Moreover, Clock regulates diurnal expression of GPX4 and PPAR-γ in mouse hippocampus and rhythmicity in KA-induced seizures. Consistent with this finding, Clock overexpression up-regulated GPX4 and PPAR-γ and protected against ferroptosis in N2a cells. In addition, luciferase reporter, mobility shift and ChIP assays showed that CLOCK trans-activated Gpx4 and Ppar-γ through direct binding to the E-box elements in the gene promoters. CLOCK protects against KA-induced seizures through increased expression of GPX4 and PPAR-γ and inhibition of ferroptosis.

High FGF-21 level in a cohort of 22 patients with Dravet Syndrome-Possible relationship with the disease outcomes.

ObjectiveDravet syndrome (DS) is a severe and intractable form of epilepsy with prolonged seizures which may evolve to other seizure types and associated with mild‐to‐severe intellectual disabilities. Fibroblast growth factor 21 (FGF‐21) is a stress hormone mediating metabolic and oxidative stress and circulating level of FGF‐21 had been shown to increase in some patients with impairment of oxidative phosphorylation in muscles. In DS, FGF‐21 is of interest for further study as mitochondrial oxidative stress was identified previously in patients.MethodsPlasma FGF‐21 levels were compared between 22 DS patients and 22 normal controls, and their clinical characteristics of DS patients at the time of plasma sampling were studied retrospectively. Besides, the relationships of FGF‐21 level with intellectual development, seizure frequency, valproate treatment, and types of SCN1A mutations were analyzed. Logarithmic transformation of FGF‐21 levels was performed before comparison and statistical analysis.ResultsMean of log10 FGF‐21 level was significantly higher in DS patients when comparing with normal controls (P = .0042). Mean of log10 FGF‐21 level was significantly higher in DS patients with normal‐to‐mild ID versus mild‐to‐severe ID (P = .0193) and with valproate treatment versus without valproate treatment (P = .015). No significant difference was shown in FGF‐21 level in DS patients with missense versus truncating SCN1A variants, and no correlation could be demonstrated between seizure frequency and FGF‐21 level.SignificanceSignificantly higher level of plasma FGF‐21 was identified in DS patients. The high FGF‐21 levels were shown to be associated with developmental outcome and valproate treatment. These results support further investigation on the relationship of FGF‐21 with the clinical outcomes of DS and other related mechanism which is important for possible therapeutic development for this epileptic encephalopathy.

Clinical attributes and surgical outcomes of angiocentric gliomas

Angiocentric gliomas (AG) are exceedingly rare low-grade neoplasms which often present in the form of intractable epilepsy within younger patients. The current study extensively reviews all reported cases which were pathologically verified as AG in the literature to analyze clinical attributes and surgical outcomes of this neoplasm. There were 88 patients with AG reported in the literature consisting mostly of pediatric cases. The sex distribution consisted of 45 males and 36 females with the remaining seven cases not documenting sex. The average age of initial diagnosis was 16years with almost half of all diagnosed patients being within the first decade of life. In cases where extent of resection was reported, gross total resection (GTR) was achieved in 54 patients, subtotal resection (STR) in 16, and biopsy only in three. Post-operative complications were transient and only occurred in three patients with no reports of death following surgery. Only five cases reported tumor recurrence on follow-up. Eight patients had seizure recurrence post-operatively and GTR offered improved rates of seizure control when compared to STR (p=0.0005). Nearly half of the cases of AG are diagnosed within the first decade of life and they usually manifest with intractable seizures. GTR appears to offer better seizure control in the post-operative period. Surgical resection is the mainstay therapy for AG as post-operative complications and tumor recurrence remain uncommon. Since the number of reported cases is limited, future studies with longer follow-up periods will help elaborate more long-term outcomes.

A prospective study of dexamethasone therapy in refractory epileptic encephalopathy with continuous spike-and-wave during sleep.

Epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS) is an intractable form of epilepsy that has no consensus protocol for corticosteroid therapy. This prospective study aimed to evaluate the efficacy and tolerability of dexamethasone for the treatment of CSWS. Patients (age: 4 years to 12 years and 5 months) with CSWS that failed to respond to several antiepileptic drugs and prednisolone at our pediatric neurology outpatient clinic between 2007 and 2015 were treated with dexamethasone and prospectively analyzed. An initial 4-week dexamethasone (0.15 mg/kg/day p.o.) scheme was employed, and response was assessed. If effective, dexamethasone was maintained for 2-3 months and then slowly weaned over several months, depending on individual patient response at each follow-up. Systemic evaluations (clinical evaluations, electroencephalography recordings, and analysis of side effects) were performed regularly thereafter. Among 15 patients, 7 were defined as initial responders after 4-week dexamethasone treatment based on comprehensive clinical and electroencephalogram evaluations. The duration of dexamethasone treatment (including weaning) in these 7 patients was 6 to 10 months, and the follow-up duration was 6 months to 7 years. Three patients had no relapse after dexamethasone withdrawal at last follow-up. Among the other 4 patients, relapse was observed during dexamethasone withdrawal (n=1) or at 2-6 months after discontinuation of dexamethasone therapy (n=3). There were no serious or life-threatening side effects, and all observed side effects were reversible after discontinuation of dexamethasone. Continuous oral dexamethasone treatment is an effective and tolerable therapy and should be an option for the treatment of CSWS.

How is homeostatic plasticity important in epilepsy?

Maintaining physiological variables within narrow operating limits by homeostatic mechanisms is a fundamental property of most if not all living cells and organisms. In recent years, research from many laboratories has shown that the activity of neurons and neural circuits are also homeostatically regulated. Here, we attempt to apply concepts of homeostasis in general, and more specifically synaptic homeostatic plasticity, to the study of epilepsy. We hypothesize that homeostatic mechanisms are actively engaged in the epileptic brain. These processes attempt to re-establish normal neuronal and network activity, but are opposed by the concurrent mechanisms underlying epileptogenesis. In forms of intractable epilepsy, seizures are so frequent and intense that homeostatic mechanisms are unable to restore normal levels of neuronal activity. In such cases, we contend that homeostatic plasticity mechanisms nevertheless remain active. However, their continuing attempts to reset neuronal activity become maladaptive and results in dyshomeostasis with neurobehavioral consequences. Using the developing hippocampus as a model system, we briefly review experimental results and present a series of arguments to propose that the cognitive neurobehavioral comorbidities of childhood epilepsy result, at least in part, from unchecked homeostatic mechanisms.

The Brain Topology of Fast Ripples, and their Correlation with Epilepsy

High frequency oscillations (ripples 80-250 Hz and fast ripples 250-600 Hz) have been widely studied in the last decade for their potential role as a more precise biomarker of the seizure onset zone, in particular fast ripples. The hippocampus is the best described brain topology as well as its association with this activity. However, in recent years; several groups have analyzed the association of high frequency activity with extra-temporal epilepsies, which could eventually influence the decision making process in the pre-surgical evaluation ensuring a better outcome in patients suffering from different forms of intractable epilepsy. In this review, the brain topology of fast ripples and several human pre-surgical studies were analyzed using fast ripple activity as an epileptogenic biomarker, also it was reviewed the preferred methods of recording for detecting high frequency oscillations in every case.

Evidence for clinical, genetic and biochemical variability in spinal muscular atrophy with progressive myoclonic epilepsy

Spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME) is a recently delineated, autosomal recessive condition caused by rare mutations in the N-acylsphingosine amidohydrolase 1 (acid ceramidase) ASAH1 gene. It is characterized by motor neuron disease followed by progressive myoclonic seizures and eventual death due to respiratory insufficiency. Here we report an adolescent female who presented with atonic and absence seizures and myoclonic jerks and was later diagnosed as having myoclonic-absence seizures. An extensive genetic and metabolic work-up was unable to arrive at a molecular diagnosis. Whole exome sequencing (WES) identified two rare, deleterious mutations in the ASAH1 gene: c.850G>T;p.Gly284X and c.456A>C;p.Lys152Asn. These mutations were confirmed by Sanger sequencing in the patient and her parents. Functional studies in cultured fibroblasts showed that acid ceramidase was reduced in both overall amount and enzymatic activity. Ceramide level was doubled in the patient's fibroblasts as compared to control cells. The results of the WES and the functional studies prompted an electromyography (EMG) study that showed evidence of motor neuron disease despite only mild proximal muscle weakness. These findings expand the phenotypic spectrum of SMA-PME caused by novel mutations in ASAH1 and highlight the clinical utility of WES for rare, intractable forms of epilepsy.

Pedunculopontine nucleus stimulation: A novel therapeutic technique in intractable epilepsy

Intractable epilepsy accounts for approximately 30% cases of epilepsy worldwide, and continues to pose a medical challenge even today. Several studies have demonstrated the strong anti-epileptic influence of rapid eye movement (REM) sleep in humans, some researchers even claiming it as the most potent anti-epileptic state in human sleep–wake cycle. A reduction of REM sleep is a common feature reported in various forms of intractable epilepsy. Several studies have reported reduction to total disappearance of even the severe EEG abnormalities in West syndrome during REM sleep suggesting an explorable relation between the reduction of REM sleep and severity/intractability of seizures.

Neuropathologic Studies of 'Epileptogenic' Tissue

This mini-review will summarize some of the major contributions of Neuropathology to understanding the structural basis of several forms of intractable epilepsy. Because of space limitations, only selected morphologically defined brain abnormalities will be considered and illustrated. By definition, the types of specimen encountered by Neuropathologists are those resected to treat intractable seizure disorders. One can therefore infer that the 'lesions' encountered in some way caused or at least contributed to the epilepsy, though the leap from observed neuropathologic abnormalities to 'seizuregenesis' is not always straightforward—indeed often is very tortuous and obscure. Nevertheless, a Neuropathologist working with a team of neurologists, neurosurgeons, electrophysiologists, neuropsychologists, and others, can contribute to a richer understanding of why seizures are triggered within human brain tissue, and therefore how they may be more effectively treated.

The promise of an interneuron‐based cell therapy for epilepsy

Of the nearly 3 million Americans diagnosed with epilepsy, approximately 30% are unresponsive to current medications. Recent data has shown that early postnatal transplantation of interneuronal precursor cells increases GABAergic inhibition in the host brain and dramatically suppresses seizure activity in epileptic mice. In this review, we will highlight findings from seizure-prone mice and humans that demonstrate the link between dysfunctional GABAergic inhibition and hyperexcitability. In particular, we will focus on rodent models of temporal lobe epilepsy, the most common and difficult to treat form of the disease, and interneuronopathies, an emerging classification. A wealth of literature showing a causal link between reduced GABA-mediated inhibition and seizures has directed our efforts to recover the loss of inhibition via transplantation of interneuronal precursors. Numerous related studies have explored the anticonvulsant potential of cell grafts derived from a variety of brain regions, yet the mechanism underlying the effect of such heterogeneous cell transplants is unknown. In discussing our recent findings and placing them in context with what is known about epilepsy, and how related transplant approaches have progressed, we hope to initiate a frank discussion of the best path toward the translation of this approach to patients with intractable forms of epilepsy.

Do subtle cortical structure changes indicate a developmental basis for temporal lobe epilepsy?

Mesial temporal lobe epilepsy (MTLE) is the most prevalent form of intractable epilepsy in adolescents and adults. It is also one of the most intensively studied. The pathologic hallmark of classic MTLE is hippocampal sclerosis (HS). This is characterized histologically by a specific pattern of neuronal loss and synaptic reorganization. On MRI, one often observes reduced hippocampal volume with increased T2 signal. One of the oldest debates in epilepsy is whether HS is a preexisting cause or effect of the seizures in MTLE. Cogent arguments have been made in both directions, but have been based on differing rationales and investigational methods. The coexistence of HS with cortical dysplasia and more subtle types of developmental anomalies at the histologic level suggest that, in some cases, HS and MTLE may represent later manifestations of a process that begins earlier in life.1,2 In this issue of Neurology ®, Voets et al.3 provide new insight into this question by demonstrating subtle changes in structure and spatial orientation of limbic cortex and hippocampus based on MRI in 43 patients with MTLE and HS. By documenting the presence of increased folding complexity of limbic cortex and malrotation of hippocampi in these …

Paediatric neurology: advances on many fronts

Paediatric neurology: advances on many fronts

Book Review

Progress in Brain Research, Vol. 135: Do Seizures Damage the Brain. Thomas Sutula and Asla Pitkanen, eds. Elsevier, Amsterdam, The Netherlands, 2002, 544 pp. This volume represents a very up-to-date, comprehensive assessment, through historical reviews and reports of original work, pertaining to the increasingly important question of whether seizures give rise to brain damage, and if so, how much and what kind. The book is arranged in sections related to various clinical and experimental theses. The summaries at the end of the sections are helpful for the reader who may be unfamiliar with the field or who chooses, for whatever reason, to select for reading only certain topics of personal interest. The compendium consists of far too numerous contributions to name all the authors who provide important observations; thus my comments are of a generic topical nature. The wide range of topics include a wealth of experimental evidence in both mature and immature animals, a consideration of some of the pitfalls in the technology involved in demonstrating damage, and the clinical evidence of progression, or lack of progression, of damage to the human brain by various types of repeated seizures. Within the context of the foregoing, the reader will appreciate that the morphologic identification of cell loss constitutes the most important determination of “damage” to the brains of experimental animals and the histologic examination of human material, as well as the presumed reflection in the reduced volumetric loss from analyses of magnetic resonance imaging in both animals and human patients. Thus the attention paid to the pitfalls and the various methodologic problems that arise in counting neurons both are educational and represent a timely and important contribution to an understanding of this field. The morphologic characteristics of excitotoxic and accelerated apoptotic death of neurons, and the important genetic considerations in the metabolic pathways supporting these mechanisms of cell death are well outlined. Numerous chapters are devoted to both the experimental morphologic and clinical consequences of status epilepticus, as well as “occasional,”“brief,”“recurrent,” and/or “prolonged'' seizures. These put into perspective the available evidence pertaining to the severity, if any, of the potential damage caused by each to the brain, the potential additive and injurious effects of each, and the important consideration of the static, versus the dynamic (progressive), effects of various combinations of seizure types. The penultimate section addresses the issue of the neuropsychological consequences of seizures, discussing the often noted increasing deficits that occur over time, including some of the difficulties of using such indirect data to support “progression” (i.e., progressive damage) in human epileptic disorders. As in other sections, a discussion of the problems of interpretation of these human observations is included, vis-à-vis whether they simply reflect a progression of an underlying etiology, or indeed reflect the triggering, by the seizures, of a dynamic progressive disorder including seizures and cognitive decline. Although the final section deals with “implications for management,” it perhaps deals less with the practical aspects of management than with a review of the possible future implications of management from both the reported observations and the possible anticipated future observations arising out of extensions of the work noted in the volume. As with the objective evaluation of most good research, perhaps more questions have been raised than answered in the contributions to the volume. However, based on the information in this text, the reader will be in a good position to provide questions that will be better formulated, will be more testable, and will provide a better ongoing continuum of improved understanding of why and how seizures of different types may lead to injury to the brain. In summary, Do Seizures Damage the Brain is a “must reference” for comprehensive epilepsy programs, especially those dealing with intractable forms of epilepsy in particular. The implications of the effects of even occasional seizures on the brain promise to become of increasing importance in decisions about management of complex seizure disorders. This has perhaps become one of the most important fields in the neurosciences, in which the observations of both the laboratory scientist and the clinician on the wards are necessary for the provision of a truly meaningful understanding of the morphology and biology of the injurious effects of seizures on the brain. As indicated at the outset, this book certainly provides the field with a comprehensive up-to-date account of the clinical and experimental observations that pertain to this question, as well as providing the reader with opportunities for considering future research in the field.

Hippocampal heterotopia with molecular and electrophysiological properties of neocortical neurons

Cortical malformations resulting from aberrant brain development can be associated with mental retardation, dyslexia, and intractable forms of epilepsy. Despite emerging interest in the pathology and etiology of cortical malformations, little is known about the phenotype of cells within these lesions. In utero exposure to the DNA methylating agent methylazoxymethanol acetate (MAM) during a critical stage in neurodevelopment results in animals with distinct clusters of displaced neurons in hippocampus, i.e. nodular heterotopia. Here we examined the molecular and electrophysiological properties of cells within hippocampal heterotopia using rats exposed to MAM during gestation. Molecular analysis revealed that heterotopic cells do not express mRNA markers normally found in hippocampal pyramidal cells or dentate granule cells ( SCIP, Math-2, Prox-1, neuropilin-2). In contrast, Id-2 mRNA, normally abundant in Layer II-III supragranular neocortical neurons but not in CA1 pyramidal neurons, was prominently expressed in hippocampal heterotopia. Current-clamp analysis of the firing properties of heterotopic neurons revealed a striking similarity with supragranular cortical neurons. In particular, both cells were characterized by small hyperpolarizing ‘sag’ potentials, high input resistance values, slow spike-train afterhyperpolarizations, and the absence of a depolarizing afterpotential. Normotopic CA1 pyramidal neurons (e.g. pyramidal cells with normal lamination adjacent to a heterotopia) in the MAM brain exhibited molecular and electrophysiological properties that were nearly identical to those of age-matched CA1 pyramidal neurons from control rats. We conclude that neuronal heterotopiae in the hippocampus of MAM-exposed rats are comprised of neurons with a Layer II-III supragranular cortex phenotype. The MAM model, therefore, may serve as a useful tool in examination of the factors influencing aberrant brain development and epilepsy.

The evaluation of patients with intractable complex partial seizures

Conceptual advantages, together with advances in both technique and technology, have considerably altered the approach to intractable epilepsy over the past two decades. Appropriate utilization of these advances allows our evaluation of patients with intractable seizures to be much more precise and specific than was once the case and allows us to improve considerably our ability to treat patients with intractable epilepsy. We propose an algorithm for the evaluation and treatment of patients with intractable complex partial seizures. Other forms of intractable epilepsy may benefit from similar diagnostic and therapeutic approaches.