Rapid seizure-induced reduction of benzodiazepine and Zn2+ sensitivity of hippocampal dentate granule cell GABAA receptors

Alterations in GABAA receptor-mediated inhibition triggered by status epilepticus and their role in epileptogenesis and increased anxiety

The triggers of status epilepticus (SE) in non-epileptic patients can vary widely, from idiopathic causes to exposure to chemoconvulsants. Regardless of its etiology, prolonged SE can cause significant brain damage, commonly resulting in the development of epilepsy, which is often accompanied by increased anxiety. GABAA receptor (GABAAR)-mediated inhibition has a central role among the mechanisms underlying brain damage and the ensuing epilepsy and anxiety. During SE, calcium influx primarily via ionotropic glutamate receptors activates signaling cascades which trigger a rapid internalization of synaptic GABAARs; this weakens inhibition, exacerbating seizures and excitotoxicity. GABAergic interneurons are more susceptible to excitotoxic death than principal neurons. During the latent period of epileptogenesis, the aberrant reorganization in synaptic interactions that follow interneuronal loss in injured brain regions, leads to the formation of hyperexcitable, seizurogenic neuronal circuits, along with disturbances in brain oscillatory rhythms. Reduction in the spontaneous, rhythmic "bursts" of IPSCs in basolateral amygdala neurons is likely to play a central role in anxiogenesis. Protecting interneurons during SE is key to preventing both epilepsy and anxiety. Antiglutamatergic treatments, including antagonism of calcium-permeable AMPA receptors, can be expected to control seizures and reduce excitotoxicity not only by directly suppressing hyperexcitation, but also by counteracting the internalization of synaptic GABAARs. Benzodiazepines, as delayed treatment of SE, have low efficacy due to the reduction and dispersion of their targets (the synaptic GABAARs), but also because themselves contribute to further reduction of available GABAARs at the synapse; furthermore, benzodiazepines may be completely ineffective in the immature brain.

Twelve landmarks in the treatment of status epilepticus

Status epilepticus was a term which first appeared in the medical literature in 1824. In the 200 years that have passed since, treatment has undergone many changes. In this paper, 12 landmarks in the treatment of status epilepticus over this period are briefly described. This paper was presented at the 9th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures, in London in April 2024.

Mammalian models of status epilepticus - Their value and limitations

Status epilepticus (SE) is a medical and neurologic emergency that may lead to permanent brain damage, morbidity, or death. Animal models of SE are particularly important to study the pathophysiology of SE and mechanisms of SE resistance to antiseizure medications with the aim to develop new, more effective treatments. In addition to rodents (rats or mice), larger mammalian species such as dogs, pigs, and nonhuman primates are used. This short review describes and discusses the value and limitations of the most frequently used mammalian models of SE. Issues that are discussed include (1) differences between chemical and electrical SE models; (2) the role of genetic background and environment on SE in rodents; (3) the use of rodent models (a) to study the pathophysiology of SE and mechanisms of SE resistance; (b) to study developmental aspects of SE; (c) to study the efficacy of new treatments, including drug combinations, for refractory SE; (d) to study the long-term consequences of SE and identify biomarkers; (e) to develop treatments that prevent or modify epilepsy; (e) to study the pharmacology of spontaneous seizures; (4) the limitations of animal models of induced SE; and (5) the advantages (and limitations) of naturally (spontaneously) occurring SE in epileptic dogs and nonhuman primates. Overall, mammalian models of SE have significantly increased our understanding of the pathophysiology and drug resistance of SE and identified potential targets for new, more effective treatments. This paper was presented at the 9th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in April 2024.

Role of carboxylesterase and arylacetamide deacetylase in drug metabolism, physiology, and pathology

Carboxylesterases (CES1 and CES2) and arylacetamide deacetylase (AADAC), which are expressed primarily in the liver and/or gastrointestinal tract, hydrolyze drugs containing ester and amide bonds in their chemical structure. These enzymes often catalyze the conversion of prodrugs, including the COVID-19 drugs remdesivir and molnupiravir, to their pharmacologically active forms. Information on the substrate specificity and inhibitory properties of these enzymes, which would be useful for drug development and toxicity avoidance, has accumulated. Recently,in vitroandin vivostudies have shown that these enzymes are involved not only in drug hydrolysis but also in lipid metabolism. CES1 and CES2 are capable of hydrolyzing triacylglycerol, and the deletion of their orthologous genes in mice has been associated with impaired lipid metabolism and hepatic steatosis. Adeno-associated virus-mediated human CES overexpression decreases hepatic triacylglycerol levels and increases fatty acid oxidation in mice. It has also been shown that overexpression of CES enzymes or AADAC in cultured cells suppresses the intracellular accumulation of triacylglycerol. Recent reports indicate that AADAC can be up- or downregulated in tumors of various organs, and its varied expression is associated with poor prognosis in patients with cancer. Thus, CES and AADAC not only determine drug efficacy and toxicity but are also involved in pathophysiology. This review summarizes recent findings on the roles of CES and AADAC in drug metabolism, physiology, and pathology.

Current advances in rodent drug-resistant temporal lobe epilepsy models: Hints from laboratory studies

Anti-seizure drugs (ASDs) are the first choice for the treatment of epilepsy, but there is still one-third of patients with epilepsy (PWEs) who are resistant to two or more appropriately chosen ASDs, named drug-resistant epilepsy (DRE). Temporal lobe epilepsy (TLE), a common type of epilepsy usually associated with hippocampal sclerosis (HS), shares the highest proportion of drug resistance (approximately 70%). In view of the key role of the temporal lobe in memory, emotion, and other physiological functions, patients with drug-resistant temporal lobe epilepsy (DR-TLE) are often accompanied by serious complications, and surgical procedures also yield extra considerations. The exact mechanisms for the genesis of DR-TLE remain unillustrated, which makes it hard to manage patients with DR-TLE in clinical practice. Animal models of DR-TLE play an irreplaceable role in both understanding the mechanism and searching for new therapeutic strategies or drugs. In this review article, we systematically summarized different types of current DR-TLE models, and then recent advances in mechanism investigations obtained in these models were presented, especially with the development of advanced experimental techniques and tools. We are deeply encouraged that novel strategies show great therapeutic potential in those DR-TLE models. Based on the big steps reached from the bench, a new light has been shed on the precise management of DR-TLE.

Intracellular Zn(II) induced turn-on fluorescence of an L-phenylalanine-derived pseudopeptide

A C2 symmetric L-phenylalanine-derived pseudopeptide has been synthesized for selective and sensitive recognition of Zn(II) ions in aqueous-organic media. The pseudopeptidic probes exhibit intracellular Zn(II) ion-sensing capabilities as demonstrated via live-cell fluorescence studies on RAW264.7 cells. Hence, we present a bioinspired pseudopeptide for potential biological applications involving intracellular Zn(II) ion detection.

New GABA-Targeting Therapies for the Treatment of Seizures and Epilepsy: I. Role of GABA as a Modulator of Seizure Activity and Recently Approved Medications Acting on the GABA System

γ-Aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter in the mammalian brain and has been found to play an important role in the pathogenesis or the expression of many neurological diseases, including epilepsy. Although GABA can act on different receptor subtypes, the component of the GABA system that is most critical to modulation of seizure activity is the GABAA-receptor-chloride (Cl-) channel complex, which controls the movement of Cl- ions across the neuronal membrane. In the mature brain, binding of GABA to GABAA receptors evokes a hyperpolarising (anticonvulsant) response, which is mediated by influx of Cl- into the cell driven by its concentration gradient between extracellular and intracellular fluid. However, in the immature brain and under certain pathological conditions, GABA can exert a paradoxical depolarising (proconvulsant) effect as a result of an efflux of chloride from high intracellular to lower extracellular Cl- levels. Extensive preclinical and clinical evidence indicates that alterations in GABAergic inhibition caused by drugs, toxins, gene defects or other disease states (including seizures themselves) play a causative or contributing role in facilitating or maintaning seizure activity. Conversely, enhancement of GABAergic transmission through pharmacological modulation of the GABA system is a major mechanism by which different antiseizure medications exert their therapeutic effect. In this article, we review the pharmacology and function of the GABA system and its perturbation in seizure disorders, and highlight how improved understanding of this system offers opportunities to develop more efficacious and better tolerated antiseizure medications. We also review the available data for the two most recently approved antiseizure medications that act, at least in part, through GABAergic mechanisms, namely cenobamate and ganaxolone. Differences in the mode of drug discovery, pharmacological profile, pharmacokinetic properties, drug-drug interaction potential, and clinical efficacy and tolerability of these agents are discussed.

Why ketamine

We present the rationale for testing ketamine as an add-on therapy for treating benzodiazepine refractory (established) status epilepticus. In animal studies, ketamine terminates benzodiazepine refractory status epilepticus by interfering with the pathophysiological mechanisms and is a neuroprotectant. Ketamine does not suppress respiration when used for sedation and anesthesia. A Series of reports suggest that ketamine can help terminate refractory and super refractory status epilepticus. We propose to use 1 or 3 mg/Kg ketamine intravenously based on animal-to-human conversion and pharmacokinetic studies. This paper was presented at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022.

A novel genetically modified mouse seizure model for evaluating anticonvulsive and neuroprotective efficacy of an A1 adenosine receptor agonist following soman intoxication

Recently a novel humanized mouse strain has been successfully generated, in which serum carboxylesterase (CES) knock out (KO) mice (Es1-/-) were further genetically modified by knocking in (KI), or adding, the gene that encodes the human form of acetylcholinesterase (AChE). The resulting human AChE KI and serum CES KO (or KIKO) mouse strain should not only exhibit organophosphorus nerve agent (NA) intoxication in a manner more similar to humans, but also display AChE-specific treatment responses more closely mimicking those of humans to facilitate data translation to pre-clinic trials. In this study, we utilized the KIKO mouse to develop a seizure model for NA medical countermeasure investigation, and then applied it to evaluate the anticonvulsant and neuroprotectant (A/N) efficacy of a specific A1 adenosine receptor (A1AR) agonist, N-bicyclo-(2.2.1)hept-2-yl-5'-chloro-5'-deoxyadenosine (ENBA), which has been shown in a rat seizure model to be a potent A/N compound. Male mice surgically implanted with cortical electroencephalographic (EEG) electrodes a week earlier were pretreated with HI-6 and challenged with various doses (26 to 47 μg/kg, SC) of soman (GD) to determine a minimum effective dose (MED) that induced sustained status epilepticus (SSE) activity in 100% of animals while causing minimum lethality at 24 h. The GD dose selected was then used to investigate the MED doses of ENBA when given either immediately following SSE initiation (similar to wartime military first aid application) or at 15 min after ongoing SSE seizure activity (applicable to civilian chemical attack emergency triage). The selected GD dose of 33 μg/kg (1.4 x LD50) generated SSE in 100% of KIKO mice and produced only 30% mortality. ENBA at a dose as little as 10 mg/kg, IP, caused isoelectric EEG activity within minutes after administration in naïve un-exposed KIKO mice. The MED doses of ENBA to terminate GD-induced SSE activity were determined to be 10 and 15 mg/kg when treatment was given at the time of SSE onset and when seizure activity was ongoing for 15 min, respectively. These doses were much lower than in the non-genetically modified rat model, which required an ENBA dose of 60 mg/kg to terminate SSE in 100% GD-exposed rats. At MED doses, all mice survived for 24 h, and no neuropathology was observed when the SSE was stopped. The findings confirmed that ENBA is a potent A/N for both immediate and delayed (i.e., dual purposed) therapy to victims of NA exposure and serves as a promising neuroprotective antidotal and adjunctive medical countermeasure candidate for pre-clinical research and development for human application.

In the fast lane: Receptor trafficking during status epilepticus

Status epilepticus (SE) remains a significant cause of morbidity and mortality and often is refractory to standard first-line treatments. A rapid loss of synaptic inhibition and development of pharmacoresistance to benzodiazepines (BZDs) occurs early during SE, while NMDA and AMPA receptor antagonists remain effective treatments after BZDs have failed. Multimodal and subunit-selective receptor trafficking within minutes to an hour of SE involves GABA-A, NMDA, and AMPA receptors and contributes to shifts in the number and subunit composition of surface receptors with differential impacts on the physiology, pharmacology, and strength of GABAergic and glutamatergic currents at synaptic and extrasynaptic sites. During the first hour of SE, synaptic GABA-A receptors containing γ2 subunits move to the cell interior while extrasynaptic GABA-A receptors with δ subunits are preserved. Conversely, NMDA receptors containing N2B subunits are increased at synaptic and extrasynaptic sites, and homomeric GluA1 ("GluA2-lacking") calcium permeant AMPA receptor surface expression also is increased. Molecular mechanisms, largely driven by NMDA receptor or calcium permeant AMPA receptor activation early during circuit hyperactivity, regulate subunit-specific interactions with proteins involved with synaptic scaffolding, adaptin-AP2/clathrin-dependent endocytosis, endoplasmic reticulum (ER) retention, and endosomal recycling. Reviewed here is how SE-induced shifts in receptor subunit composition and surface representation increase the excitatory to inhibitory imbalance that sustains seizures and fuels excitotoxicity contributing to chronic sequela such as "spontaneous recurrent seizures" (SRS). A role for early multimodal therapy is suggested both for treatment of SE and for prevention of long-term comorbidities.

The Roles of Glutamate Receptors and Their Antagonists in Status Epilepticus, Refractory Status Epilepticus, and Super-Refractory Status Epilepticus

Status epilepticus (SE) is a neurological emergency with a high mortality rate. When compared to chronic epilepsy, it is distinguished by the durability of seizures and frequent resistance to benzodiazepine (BZD). The Receptor Trafficking Hypothesis, which suggests that the downregulation of γ-Aminobutyric acid type A (GABAA) receptors, and upregulation of N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors play major roles in the establishment of SE is the most widely accepted hypothesis underlying BZD resistance. NMDA and AMPA are ionotropic glutamate receptor families that have important excitatory roles in the central nervous system (CNS). They are both essential in maintaining the normal function of the brain and are involved in a variety of neuropsychiatric diseases, including epilepsy. Based on animal and human studies, antagonists of NMDA and AMPA receptors have a significant impact in ending SE; albeit most of them are not yet approved to be in clinically therapeutic guidelines, due to their psychomimetic adverse effects. Although there is still a dearth of randomized, prospective research, NMDA antagonists such as ketamine, magnesium sulfate, and the AMPA antagonist, perampanel, are regarded to be reasonable optional adjuvant therapies in controlling SE, refractory SE (RSE) or super-refractory SE (SRSE), though there are still a lack of randomized, prospective studies. This review seeks to summarize and update knowledge on the SE development hypothesis, as well as clinical trials using NMDA and AMPA antagonists in animal and human studies of SE investigations.

Insight into Drug Resistance in Status Epilepticus: Evidence from Animal Models

Status epilepticus (SE), a condition with abnormally prolonged seizures, is a severe type of epilepsy. At present, SE is not well controlled by clinical treatments. Antiepileptic drugs (AEDs) are the main therapeutic approaches, but they are effective for SE only with a narrow intervening window, and they easily induce resistance. Thus, in this review, we provide an updated summary for an insight into drug-resistant SE, hoping to add to the understanding of the mechanism of refractory SE and the development of active compounds. Firstly, we briefly outline the limitations of current drug treatments for SE by summarizing the extensive experimental literature and clinical data through a search of the PubMed database, and then summarize the common animal models of refractory SE with their advantages and disadvantages. Notably, we also briefly review some of the hypotheses about drug resistance in SE that are well accepted in the field, and furthermore, put forward future perspectives for follow-up research on SE.

Levetiracetam versus fosphenytoin as a second-line treatment after diazepam for adult convulsive status epilepticus: a multicentre non-inferiority randomised control trial

OBJECTIVE

Status epilepticus (SE) is an emergency condition for which rapid and secured cessation is crucial. Although fosphenytoin (FPHT) is recommended as a second-line treatment, levetiracetam (LEV) reportedly has similar efficacy, but higher safety. Therefore, we herein compared LEV with FPHT in adult SE.

METHODS

We initiated a multicentre randomised control trial in emergency departments with adult patients with convulsive SE. Diazepam was initially administered, followed intravenously by FPHT at 22.5 mg/kg or LEV at 1000-3000 mg. The primary outcome was assigned as the seizure cessation rate within 30 min of the administration of the study drug.

RESULTS

A total of 176 adult patients with SE were enrolled (82 FPHT and 94 LEV), and 3 were excluded from the full analysis set. Seizure cessation rates within 30 min were 83.8% (67/80) in the FPHT group and 89.2% (83/93) in the LEV group. The difference in these rates was 5.5% (95% CI -4.7 to 15.7, p=0.29). The non-inferiority of LEV to FPHT was confirmed with p<0.001 by the Farrington-Manning test. No significant differences were observed in the seizure recurrence rate or intubation rate within 24 hours. Serious adverse events developed in three patients in the FPHT group and none in the LEV group (p=0.061).

CONCLUSION

The efficacy of LEV was similar to that of FPHT for adult SE following the administration of diazepam. LEV may be recommended as a second-line treatment for SE along with phenytoin/FPHT.

TRIAL REGISTRATION NUMBER

jRCTs031190160.

Consequences: Bench to home

Seizure clusters (also referred to as acute repetitive seizures) consist of several seizures interspersed with brief interictal periods. Seizure clusters can break down γ-aminobutyric acidergic (GABAergic) inhibition of dentate granule cells, leading to hyperactivation. Functional changes to GABAA receptors, which play a vital neuroinhibitory role, can include altered GABAA receptor subunit trafficking and cellular localization, intracellular chloride accumulation, and dysregulation of proteins critical to chloride homeostasis. A reduction in neuroinhibition and potentiation of excitatory neurotransmission in CA1 pyramidal neurons represent pathological mechanisms that underlie seizure clusters. Benzodiazepines are well-established treatments for seizure clusters; however, there remain barriers to appropriate care. At the clinical level, there is variability in seizure cluster definitions, such as the number and/or type of seizures associated with a cluster as well as the interictal duration between seizures. This can lead to delays in diagnosis and timely treatment. There are gaps in understanding between clinicians, their patients, and caregivers regarding acute treatment for seizure clusters, such as the use of rescue medications and emergency services. This lack of consensus to define seizure clusters in addition to a lack of education for appropriate treatment can affect quality of life for patients and place a greater burden on patient families and caregivers. For patients with seizure clusters, the sense of unpredictability can lead to continuous traumatic stress, during which patients and families live with a heightened level of anxiety. Clinicians can affect patient quality of life and clinical outcomes through improved seizure cluster education and treatment, such as the development and implementation of a personalized seizure action plan as well as prescriptions for suitable rescue medications indicated for seizure clusters and instructions for their proper use. In all, the combination of targeted therapy along with patient education and support can improve quality of life.

ESIPT-Active 8-Hydroxyquinoline-Based Fluorescence Sensor for Zn(II) Detection and Aggregation-Induced Emission of the Zn(II) Complex

A D-π-A type quinoline derivative, 2-(((4-(1, 2, 2-triphenylvinyl)phenyl)imino)methyl)quinolin-8-ol (HL), was synthesized and structurally characterized. The five-membered ring formed by the O-H···N hydrogen bond in HL contributed to the excited-state intramolecular proton transfer (ESIPT) behavior of HL, which was further verified by theoretical computations. Upon coordination with Zn²⁺, the hydroxyl proton in HL was removed, resulting in the inhibition of ESIPT. In the meanwhile, the formed Zn ₂ L ₄ complex displayed aggregation-induced emission (AIE) character in THF/H₂O mixtures, which is conducive to the fluorescence enhancement in aqueous media. Structure analysis suggested that the origin of the AIE characteristic was attributed to restriction of intramolecular rotations along with the formation of J-aggregates. Based on ESIPT coupled with AIE, HL could recognize Zn(II) in aqueous media via an orange fluorescence turn-on mode. Benefitting from the AIE property, chemosensor HL was successfully applied to fabricate test strips for rapid sensing of Zn(II) ions.

Neuronal circuits sustaining neocortical-injury-induced status epilepticus

OBJECTIVES

Acute injuries or insults to the cortex, such as trauma, subarachnoid hemorrhage, lobar hemorrhage, can cause seizures or status epilepticus(SE). Neocortical SE is associated with coma, worse prognosis, delayed recovery, and the development of epilepsy. The anatomical structures progressively recruited during neocortical-onset status epilepticus (SE) is unknown. Therefore, we constructed large-scale maps of brain regions active during neocortical SE.

METHODS

We used a neocortical injury-induced SE mouse model. We implanted cobalt (Co) in the right supplementary motor cortex (M2). We 16 h later administered a homocysteine injection (845 mg/kg, intraperitoneal) to C57Bl/6 J mice to induce SE and monitored it by video and EEG. We harvested animals for 1 h (early-stage) and 2 h (late-stage) following homocysteine injections. To construct activation maps, we immunolabeled whole-brain sections for cFos and NeuN, imaged them using a confocal microscope and quantified cFos immunoreactivity (IR).

RESULTS

SE in the early phase consisted of discrete, focal intermittent seizures, which became continuous and bilateral in the late stage. In this early stage, cFos IR was primarily observed in the right hemisphere, ipsilateral to the Co lesion, specifically in the motor cortex, retrosplenial cortex, somatosensory cortex, anterior cingulate cortex, lateral and medial septal nuclei, and amygdala. We observed bilateral cFos IR in brain regions during the late stage, indicating the bilateral spread of focal seizures. We found increased cFOS IR in the bilateral somatosensory cortex and the motor cortex and subcortical regions, including the amygdala, thalamus, and hypothalamus. There was noticeably different, intense cFos IR in the bilateral hippocampus compared to the early stage. In addition, there was higher activity in the cortex ipsilateral to the seizure focus during the late stage compared with the early one.

CONCLUSION

We present a large-scale, high-resolution map of seizure spread during neocortical injury-induced SE. Cortico-cortical and cortico subcortical re-entrant circuits sustain neocortical SE. Neuronal loss following neocortical SE, distant from the neocortical focus, may result from seizures.

Beta-caryophyllene attenuates short-term recurrent seizure activity and blood-brain-barrier breakdown after pilocarpine-induced status epilepticus in rats

BACKGROUND

Status epilepticus (SE) is a neurological life-threatening condition, resulting from the failure of the mechanisms responsible for seizure termination. SE is often pharmacoresistant and associated with significant morbidity and mortality. Hence, ceasing or attenuating SE and its consequences is of fundamental importance. Beta-caryophyllene is a functional CB2 receptor agonist and exhibit a good safety profile. Besides, it displays beneficial effects in several experimental conditions, including neuroprotective activity. In the present study we aimed to investigate the effects of beta-caryophyllene on pilocarpine-induced SE.

METHODS

Wistar rats were submitted to pilocarpine-induced SE and monitored for 24 hours by video and EEG for short-term recurrence of seizure activity (i.e. seizures occurring within 24 hours after termination of SE). Rats received beta-caryophyllene (100 mg/kg, ip) at 1, 8- and 16-hours after SE. Twenty-four hours after SE we evaluated sensorimotor response, neuronal damage (fluoro jade C staining) and serum albumin infiltration into brain parenchyma.

RESULTS

Beta-caryophyllene-treated animals presented fewer short-term recurrent seizures than vehicle-treated counterparts, suggesting an anticonvulsant effect after SE. Behavioral recovery from SE and the number of fluoro jade C positive cells in the hippocampus and thalamus were not modified by beta-caryophyllene. Treatment with beta-caryophyllene attenuated the SE-induced increase of albumin immunoreactivity in the hippocampus, indicating a protective effect against blood-brain-barrier breakdown.

CONCLUSIONS

Given the inherent difficulties in the treatment of SE and its consequences, present results suggest that beta-caryophyllene deserve further investigation as an adjuvant therapeutic strategy for SE.

Benzodiazepines in the Management of Seizures and Status Epilepticus: A Review of Routes of Delivery, Pharmacokinetics, Efficacy, and Tolerability

Status epilepticus (SE) is an acute, life-threatening medical condition that requires immediate, effective therapy. Therefore, the acute care of prolonged seizures and SE is a constant challenge for healthcare professionals, in both the pre-hospital and the in-hospital settings. Benzodiazepines (BZDs) are the first-line treatment for SE worldwide due to their efficacy, tolerability, and rapid onset of action. Although all BZDs act as allosteric modulators at the inhibitory gamma-aminobutyric acid (GABA)_A receptor, the individual agents have different efficacy profiles and pharmacokinetic and pharmacodynamic properties, some of which differ significantly. The conventional BZDs clonazepam, diazepam, lorazepam and midazolam differ mainly in their durations of action and available routes of administration. In addition to the common intravenous, intramuscular and rectal administrations that have long been established in the acute treatment of SE, other administration routes for BZDs-such as intranasal administration-have been developed in recent years, with some preparations already commercially available. Most recently, the intrapulmonary administration of BZDs via an inhaler has been investigated. This narrative review provides an overview of the current knowledge on the efficacy and tolerability of different BZDs, with a focus on different routes of administration and therapeutic specificities for different patient groups, and offers an outlook on potential future drug developments for the treatment of prolonged seizures and SE.

Intranasal midazolam versus intravenous/rectal benzodiazepines for acute seizure control in children: A systematic review and meta-analysis

BACKGROUND

Acute seizure activity might cause complications including bodily harm, progression to status epilepticus, and poor quality of life in children. The introduction of a venous line may be difficult in children with seizures which would delay the initiation of treatment. Rectal drug administration can be socially awkward for patients and providers. Intranasal (IN) midazolam offers a valuable substitute that is easier and faster to administer.

OBJECTIVE

To assess the efficacy, safety, and acceptability of intranasal midazolam in children with acute seizure when compared to conventional IV or rectal benzodiazepine (BDZ).

METHODS

PubMed, google scholar, websites clinicaltrials.gov and the WHO-international clinical trials registry platform, were searched. Randomized controlled/prospective randomized trials comparing IN midazolam against IV/rectal BDZ in the treatment of acute seizures in pediatric patients were included in the meta-analysis.

RESULTS

Data of 10 studies were quantitatively analyzed. Intranasal midazolam (n = 169) when compared to IV/rectal BDZ (n = 161) has a shorter interval between hospital arrival and seizure cessation {(mean difference = -3.51; 95% CI [-6.84, -0.18]) P = 0.04}. Regarding time to seizure cessation after midazolam (n = 326) or BDZ (n = 322) administration, there is no significant difference between the two groups {(mean difference = -0.03; 95% CI [-1.30, 1.25]), P = 0.97} and both are equally effective for controlling acute seizures (odds ratio = 1.06; 95% CI [0.43, 2.63]; n = 737).

CONCLUSION

In children with acute seizures, IN midazolam is equally effective in aborting seizure and decreases the total time from hospital arrival and cessation of seizures, eventually leading to faster cessation of seizure as compared to IV/rectal BDZ.

Benzodiazepine administration patterns before escalation to second-line medications in pediatric refractory convulsive status epilepticus

Objective

This study was undertaken to evaluate benzodiazepine (BZD) administration patterns before transitioning to non‐BZD antiseizure medication (ASM) in pediatric patients with refractory convulsive status epilepticus (rSE).

Methods

This retrospective multicenter study in the United States and Canada used prospectively collected observational data from children admitted with rSE between 2011 and 2020. Outcome variables were the number of BZDs given before the first non‐BZD ASM, and the number of BZDs administered after 30 and 45 min from seizure onset and before escalating to non‐BZD ASM.

Results

We included 293 patients with a median (interquartile range) age of 3.8 (1.3–9.3) years. Thirty‐six percent received more than two BZDs before escalating, and the later the treatment initiation was after seizure onset, the less likely patients were to receive multiple BZD doses before transitioning (incidence rate ratio [IRR] = .998, 95% confidence interval [CI] = .997–.999 per minute, p = .01). Patients received BZDs beyond 30 and 45 min in 57.3% and 44.0% of cases, respectively. Patients with out‐of‐hospital seizure onset were more likely to receive more doses of BZDs beyond 30 min (IRR = 2.43, 95% CI = 1.73–3.46, p < .0001) and beyond 45 min (IRR = 3.75, 95% CI = 2.40–6.03, p < .0001) compared to patients with in‐hospital seizure onset. Intermittent SE was a risk factor for more BZDs administered beyond 45 min compared to continuous SE (IRR = 1.44, 95% CI = 1.01–2.06, p = .04). Forty‐seven percent of patients (n = 94) with out‐of‐hospital onset did not receive treatment before hospital arrival. Among patients with out‐of‐hospital onset who received at least two BZDs before hospital arrival (n = 54), 48.1% received additional BZDs at hospital arrival.

Significance

Failure to escalate from BZDs to non‐BZD ASMs occurs mainly in out‐of‐hospital rSE onset. Delays in the implementation of medical guidelines may be reduced by initiating treatment before hospital arrival and facilitating a transition to non‐BZD ASMs after two BZD doses during handoffs between prehospital and in‐hospital settings.

Time to Treatment in Pediatric Convulsive Refractory Status Epilepticus: The Weekend Effect

BACKGROUND

Time to treatment in pediatric refractory status epilepticus is delayed. We aimed to evaluate the influence of weekends and holidays on time to treatment of this pediatric emergency.

METHODS

We performed a retrospective analysis of prospectively collected observational data of pediatric patients with refractory status epilepticus.

RESULTS

We included 329 patients (56% males) with a median (p25 to p75) age of 3.8 (1.3 to 9) years. The median (p25 to p75) time to first BZD on weekdays and weekends/holidays was 20 (6.8 to 48.3) minutes versus 11 (5 to 35) minutes, P = 0.01; adjusted hazard ratio (HR) = 1.20 (95% confidence interval [CI]: 0.95 to 1.55), P = 0.12. The time to first non-BZD ASM was longer on weekdays than on weekends/holidays (68 [42.8 to 153.5] minutes versus 59 [27 to 120] minutes, P = 0.006; adjusted HR = 1.38 [95% CI: 1.08 to 1.76], P = 0.009). However, this difference was mainly driven by status epilepticus with in-hospital onset: among 108 patients, the time to first non-BZD ASM was longer during weekdays than during weekends/holidays (55.5 [28.8 to 103.5] minutes versus 28 [15.8 to 66.3] minutes, P = 0.003; adjusted HR = 1.65 [95% CI: 1.08 to 2.51], P = 0.01).

CONCLUSIONS

The time to first non-BZD ASM in pediatric refractory status epilepticus is shorter on weekends/holidays than on weekdays, mainly driven by in-hospital onset status epilepticus. Data on what might be causing this difference may help tailor policies to improve medication application timing.

Evaluation and Management of Seizures and Status Epilepticus

Seizures are frequently triggered by an inciting event and result from uninhibited excitation and/or decreased inhibition of a pool of neurons. If physiologic seizure abortive mechanisms fail, the ensuing unrestrained synchronization of neurons-status epilepticus-can be life-threatening and is associated with the potential for marked morbidity in survivors and high medical care costs. Prognosis is intimately related to etiology and its response to therapeutic measures. Timely implementation of pharmacologic therapy while concurrently performing a stepwise workup for etiology are paramount. Neurodiagnostic testing should guide titration of pharmacologic therapies, and help determine if there is a role for immune modulation.

Neuroprotection by delayed triple therapy following sarin nerve agent insult in the rat

The development of refractory status epilepticus (SE) induced by sarin intoxication presents a therapeutic challenge. In our current research we evaluate the efficacy of a delayed combined triple treatment in ending the abnormal epileptiform seizure activity (ESA) and the ensuing of long-term neuronal insult. SE was induced in male Sprague-Dawley rats by exposure to 1.2LD50 sarin insufficiently treated by atropine and TMB4 (TA) 1 min later. Triple treatment of ketamine, midazolam and valproic acid was administered 30 min or 1 h post exposure and was compared to a delayed single treatment with midazolam alone. Toxicity and electrocorticogram activity were monitored during the first week and behavioral evaluation performed 3 weeks post exposure followed by brain biochemical and immunohistopathological analyses. The addition of both single and triple treatments reduced mortality and enhanced weight recovery compared to the TA-only treated group. The triple treatment also significantly minimized the duration of the ESA, reduced the sarin-induced increase in the neuroinflammatory marker PGE2, the brain damage marker TSPO, decreased the gliosis, astrocytosis and neuronal damage compared to the TA+ midazolam or only TA treated groups. Finally, the triple treatment eliminated the sarin exposed increased open field activity, as well as impairing recognition memory as seen in the other experimental groups. The delayed triple treatment may serve as an efficient therapy, which prevents brain insult propagation following sarin-induced refractory SE, even if treatment is postponed for up to 1 h.

Levetiracetam versus fosphenytoin as a second-line treatment after diazepam for status epilepticus: study protocol for a multicenter non-inferiority designed randomized control trial

BACKGROUND

Status epilepticus (SE) is an emergency condition for which rapid and secured cessation is important. Phenytoin and fosphenytoin, the prodrug of phenytoin with less severe adverse effects, have been recommended as second-line treatments. However, fosphenytoin causes severe adverse events, such as hypotension and arrhythmia. Levetiracetam reportedly has similar efficacy and higher safety for SE; however, evidence to support its use for adult SE is lacking. In the present study, a non-inferiority designed multicenter randomized controlled trial (RCT) is being conducted to compare levetiracetam with fosphenytoin after diazepam as a second-line treatment for SE.

METHODS

This multicenter, prospective, and open-label RCT is conducted in emergency departments. Between December 23, 2019, and March 31, 2023, 176 patients with convulsive SE transported to an emergency room will be randomized into a fosphenytoin group and levetiracetam group at a ratio of 1:1. The definition of SE is "continuous seizures longer than 5 min or discrete seizures longer than 2 min with intervening consciousness disturbance." In both groups, diazepam is initially administered at 1-20 mg, followed by intravenous fosphenytoin at 22.5 mg/kg or intravenous levetiracetam at 1000-3000 mg. The primary outcome is the seizure cessation rate within 30 min. Seizure recurrence within 24 h, severe adverse events, and intubation rate within 24 h are secondary outcomes.

DISCUSSION

The present study was approved and conducted as an initiative study of the Japanese Association for Acute Medicine. If non-inferiority is identified, the society will pursue an application for the national health insurance coverage of levetiracetam for SE via a public knowledge-based application.

TRIAL REGISTRATION

Japan Registry of Clinical Trials jRCTs031190160 . Registered on December 13, 2019.

Pharmacotherapy for Nonconvulsive Seizures and Nonconvulsive Status Epilepticus

Most seizures in critically ill patients are nonconvulsive. A significant number of neurological and medical conditions can be complicated by nonconvulsive seizures (NCSs) and nonconvulsive status epilepticus (NCSE), with brain infections, hemorrhages, global hypoxia, sepsis, and recent neurosurgery being the most prominent etiologies. Prolonged NCSs and NCSE can lead to adverse neurological outcomes. Early recognition requires a high degree of suspicion and rapid and appropriate duration of continuous electroencephalogram (cEEG) monitoring. Although high quality research evaluating treatment with antiseizure medications and long-term outcome is still lacking, it is probable that expeditious pharmacological management of NCSs and NCSE may prevent refractoriness and further neurological injury. There is limited evidence on pharmacotherapy for NCSs and NCSE, although a few clinical trials encompassing both convulsive and NCSE have demonstrated similar efficacy of different intravenous (IV) antiseizure medications (ASMs), including levetiracetam, valproate, lacosamide and fosphenytoin. The choice of specific ASMs lies on tolerability and safety since critically ill patients frequently have impaired renal and/or hepatic function as well as hematological/hemodynamic lability. Treatment frequently requires more than one ASM and occasionally escalation to IV anesthetic drugs. When multiple ASMs are required, combining different mechanisms of action should be considered. There are several enteral ASMs that could be used when IV ASM options have been exhausted. Refractory NCSE is not uncommon, and its treatment requires a very judicious selection of ASMs aiming at reducing seizure burden along with management of the underlying condition.

Epilepsy Associated Depression: An Update on Current Scenario, Suggested Mechanisms, and Opportunities

Depression is one of the most frequent psychiatric comorbidities associated with epilepsy having a major impact on the patient's quality of life. Several screening tools are available to identify and follow up psychiatric disorders in epilepsy. Out of various psychiatric disorders, people with epilepsy (PWE) are at greater risk of developing depression. This bidirectional relationship further hinders pharmacotherapy of comorbid depression in PWE as some antiepileptic drugs (AEDs) worsen associated depression and coadministration of existing antidepressants (ADs) to alleviate comorbid depression has been reported to worsen seizures. Selective serotonin reuptake inhibitors (SSRIs) and selective serotonin and norepinephrine reuptake inhibitors (SNRIs) are first choice of ADs and are considered safe in PWE, but there are no high-quality evidences. Similar to observations in people with depression, PWE also showed pharmacoresistant to available SSRI/SNRIs, which further complicates the disease prognosis. Randomized double-blind placebo-controlled clinical trials are necessary to report efficacy and safety of available ADs in PWE. We should also move beyond ADs, and therefore, we reviewed common pathological mechanisms such as neuroinflammation, dysregulated hypothalamus pituitary adrenal (HPA) axis, altered neurogenesis, and altered tryptophan metabolism responsible for coexistent relationship of epilepsy and depression. Based on these common pertinent pathways involved in the genesis of epilepsy and depression, we suggested novel targets and therapeutic approaches for safe management of comorbid depression in epilepsy.

Factors associated with resistance to benzodiazepines in status epilepticus

OBJECTIVE

To investigate factors related to benzodiazepine (BZD) resistance in status epilepticus (SE) with a focus on their relationship with the etiology of the episode.

METHODS

All SE cases in patients aged >16 years treated with BZDs were prospectively collected in our center from February 2011 to April 2019. The registry included demographics, SE type and etiology, the timing and duration of BZD administration, and the outcome. In total, 371 episodes were analyzed.

RESULTS

Median age at SE onset was 61.3 years; the most frequent etiology was acute symptomatic (55.8%). SE with prominent motor symptoms occurred in 63.3%. Median time to BZD administration was 2 h. We studied the correlation between two-time variables: time from SE onset to BZD administration and time from BZD administration to resolution of SE (response); we observed that timely administration correlated with a faster response in patients with prominent motor symptoms (p = 0.017), SE due to a chronic structural cerebral lesion (p = 0.004), and patients with a history of seizures (p = 0.013). In these subgroups (prominent motor symptoms or chronic structural lesion) BZD administration within the first 4.5 h was highly associated with shorter post-BZD SE duration (p < 0.001).

SIGNIFICANCE

The relationship between prompt BZD administration and subsequent duration of SE was found to depend to some extent on the etiology of the episode: patients with chronic structural lesions and those with previous epilepsy responded faster to BZDs. Semiology may have also its impact, as the presence of prominent motor symptoms showed also a faster response.

Patterns of benzodiazepine underdosing in the Established Status Epilepticus Treatment Trial

OBJECTIVE

This study was undertaken to describe patterns of benzodiazepine use as first-line treatment of status epilepticus (SE) and test the association of benzodiazepine doses with response to second-line agents in patients enrolled in the Established Status Epilepticus Treatment Trial (ESETT).

METHODS

Patients refractory to an adequate dose of benzodiazepines for the treatment of SE were enrolled in ESETT. Choice of benzodiazepine, doses given prior to administration of second-line agent, route of administration, setting, and patient weight were characterized. These were compared with guideline-recommended dosing. Logistic regression was used to determine the association of the first dose of benzodiazepine and the cumulative benzodiazepine dose with the response to second-line agent.

RESULTS

Four hundred sixty patients were administered 1170 doses of benzodiazepines (669 lorazepam, 398 midazolam, 103 diazepam). Lorazepam was most frequently administered intravenously in the emergency department, midazolam intramuscularly or intravenously by the emergency medical services personnel, and diazepam rectally prior to ambulance arrival. The first dose of the first benzodiazepine (N = 460) was lower than guideline recommendations in 76% of midazolam administrations and 81% of lorazepam administrations. Among all administrations, >85% of midazolam and >76% of lorazepam administrations were lower than recommended. Higher first or cumulative benzodiazepine doses were not associated with better outcomes or clinical seizure cessation in response to second-line medications in these benzodiazepine-refractory seizures.

SIGNIFICANCE

Benzodiazepines as first-line treatment of SE, particularly midazolam and lorazepam, are frequently underdosed throughout the United States. This broad and generalizable cohort confirms prior single site reports that underdosing is both pervasive and difficult to remediate. (ESETT ClinicalTrials.gov identifier: NCT01960075.).

A Short Review on the Intranasal Delivery of Diazepam for Treating Acute Repetitive Seizures

Benzodiazepines such as diazepam, lorazepam and midazolam remained the mainstay of treatment for acute repetitive seizures (ARS). The immediate care for ARS should often begin at home by a caregiver. This prevents the progression of ARS to prolonged seizures or status epilepticus. For a long time and despite social objections rectal diazepam gel remained only FDA-approved rescue medication. Intranasal administration of benzodiazepines is considered attractive and safe compared with rectal, buccal and sublingual routes. Intranasal delivery offers numerous advantages such as large absorptive surface area, bypass the first-pass metabolism and good patient acceptance as it is needle free and painless. Recent clinical studies have demonstrated that diazepam nasal spray (NRL-1; Valtoco^®, Neurelis Inc.,San Diego, CA, USA) showed less pharmacokinetic variability and reliable bioavailability compared with the diazepam rectal gel. Diazepam nasal spray could be considered as a suitable alternative for treating seizure emergencies outside the hospital. This review summarizes the treatment options for ARS and findings from clinical studies involving intranasal diazepam for treating seizure emergencies.

Status Epilepticus-Work-Up and Management in Children

Status epilepticus (SE) is one of the most common neurological emergencies in children and has a mortality of 2 to 4%. Admissions for SE are very resource-consuming, especially in refractory and super-refractory SE. An increasing understanding of the pathophysiology of SE leaves room for improving SE treatment protocols, including medication choice and timing. Selecting the most efficacious medications and giving them in a timely manner may improve outcomes. Benzodiazepines are commonly used as first line and they can be used in the prehospital setting, where most SE episodes begin. The diagnostic work-up should start simultaneously to initial treatment, or as soon as possible, to detect potentially treatable causes of SE. Although most etiologies are recognized after the first evaluation, the detection of more unusual causes may become challenging in selected cases. SE is a life-threatening medical emergency in which prompt and efficacious treatment may improve outcomes. We provide a summary of existing evidence to guide clinical decisions regarding the work-up and treatment of SE in pediatric patients.

Ketamine as adjunct to midazolam treatment following soman-induced status epilepticus reduces seizure severity, epileptogenesis, and brain pathology in plasma carboxylesterase knockout mice

Delayed treatment of cholinergic seizure results in benzodiazepine-refractory status epilepticus (SE) that is thought, at least in part, to result from maladaptive trafficking of N-methyl-d-aspartate (NMDA) and gamma-aminobutyric acid type A (GABA_A) receptors, the effects of which may be ameliorated by combination therapy with the NMDA receptor antagonist ketamine. Our objective was to establish whether ketamine and midazolam dual therapy would improve outcome over midazolam monotherapy following soman (GD) exposure when evaluated in a mouse model that, similar to humans, lacks plasma carboxylesterase, greatly reducing endogenous scavenging of GD. In the current study, continuous cortical electroencephalographic activity was evaluated in male and female plasma carboxylesterase knockout mice exposed to a seizure-inducing dose of GD and treated with midazolam or with midazolam and ketamine combination at 40 min after seizure onset. Ketamine and midazolam combination reduced GD-induced lethality, seizure severity, and the number of mice that developed spontaneous recurrent seizure (SRS) compared with midazolam monotherapy. In addition, ketamine-midazolam combination treatment reduced GD-induced neuronal degeneration and microgliosis. These results support that combination of antiepileptic drug therapies aimed at correcting the maladaptive GABA_A and NMDA receptor trafficking reduces the detrimental effects of GD exposure. Ketamine may be a beneficial adjunct to midazolam in reducing the epileptogenesis and neuroanatomical damage that follows nerve agent exposure and pharmacoresistant SE.

Study on the mechanism of high-frequency stimulation inhibiting low-Mg2+-induced epileptiform discharges in juvenile rat hippocampal slices

Study on the mechanism of high-frequency stimulation inhibiting low-Mg²⁺-induced epileptiform discharges in juvenile rat hippocampal slices High-frequency stimulation (HFS) has been demonstrated to be an effective treatment for inhibiting epilepsy in some clinical and laboratory studies. However, the mechanisms underlying the therapeutic effects of HFS are not yet fully understood. In our present study, epileptiform discharges (EDs) in acutely isolated hippocampal slices of male Sprague-Dawley (SD) juvenile rats induced by low-Mg²⁺ artificial cerebrospinal fluid (ACSF), and electrical stimulation (square wave, 900 pulses, 50 % duty-cycle, 130 Hz) was performed on the CA3 using concentric bipolar electrodes. EDs of neurons in hippocampal were recorded by multi-electrode arrays (MEA). After stable EDs events had been recorded for at least 20 min, HFS was added, followed by 10 μmol/L gamma-aminobutyric acid type A (GABA_A) receptors blocker bicuculline (BIC). The results show that the HFS can increase the discharges frequency of inter-ictal discharges (IIDs) and decrease the duration of ictal discharges (IDs). However, the HFS had no effect on the slices with 10 μmol/L BIC. These results indicated that the GABA_A receptors are activated when HFS inhibited EDs, thereby achieving the inhibition of low-Mg²⁺-induced EDs in slices.

The evolution of the pilocarpine animal model of status epilepticus

The pilocarpine animal model of status epilepticus is a well-established, clinically translatable model that satisfies all of the criteria essential for an animal model of status epilepticus: a latency period followed by spontaneous recurrent seizures, replication of behavioural, electrographic, metabolic, and neuropathological changes, as well as, pharmacoresistance to anti-epileptic drugs similar to that observed in human status epilepticus. However, this model is also characterized by high mortality rates and studies in recent years have also seen difficulties in seizure induction due to pilocarpine resistant animals. This can be attributed to differences in rodent strains, species, gender, and the presence of the multi-transporter, P-glycoprotein at the blood brain barrier. The current paper highlights the various alterations made to the original pilocarpine model over the years to combat both the high mortality and low induction rates. These range from the initial lithium-pilocarpine model to the more recent Reduced Intensity Status Epilepticus (RISE) model, which finally brought the mortality rates down to 1%. These modifications are essential to improve animal welfare and future experimental outcomes.

Levetiracetam vs. Fosphenytoin for Second-Line Treatment of Status Epilepticus: Propensity Score Matching Analysis Using a Nationwide Inpatient Database

Objective: Status epilepticus is a major emergency condition. The choice of antiepileptic drugs for second-line treatment after benzodiazepine remains controversial, including levetiracetam vs. fosphenytoin. We compare the safety of intravenous levetiracetam and fosphenytoin as a second-line treatment in patients with status epilepticus using a nationwide database.

Methods: An observational study conducted with the Japanese Diagnosis Procedure Combination inpatient database identified adult patients who had been admitted for status epilepticus and who had received intravenous diazepam on the day of admission from March 1, 2011 to March 31, 2018. Patients who received intravenous levetiracetam on the day of admission were defined as the levetiracetam group and those who received intravenous fosphenytoin on the day of admission were defined as the fosphenytoin group. Propensity score matching was performed to compare outcomes obtained for the levetiracetam and fosphenytoin groups.

Results: The analysis examined data of 5,667 patients. Overall, 1,403 (25%) patients received levetiracetam; 4,264 (75%) received fosphenytoin. One-to-one propensity score matching created 1,363 matched pairs. No significant difference was found in in-hospital mortality (5.2 vs. 5.1%; odds ratio, 1.03; 95% confidence interval, 0.73–1.46). The proportion of vasopressor use on the day of admission was significantly lower for the levetiracetam group than for the fosphenytoin group (3.2 vs. 4.9%; odds ratio, 0.63; 95% confidence interval, 0.43–0.92). No significant difference was found in other secondary outcomes including total hospitalization cost.

Conclusion: Levetiracetam was related to significantly reduced vasopressor use on the day of admission than that found for fosphenytoin, in adult status epilepticus.

Phenytoin versus fosphenytoin for second-line treatment of status epilepticus: propensity score matching analysis using a nationwide inpatient database

PURPOSE

For status epilepticus, the choice of antiepileptic drugs for second-line treatment after benzodiazepine remains controversial: phenytoin or fosphenytoin are recommended, however, it has been unknown which is better. Using a nationwide database, we compared the efficacy and safety of them.

METHOD

An observational study conducted with the Japanese Diagnosis Procedure Combination inpatient database identified adult patients who had been admitted for status epilepticus and who had received intravenous diazepam on the day of admission from January 1, 2011 through December 31, 2015. Propensity score matching was applied to compare outcomes of the phenytoin and fosphenytoin groups.

RESULTS

The analysis examined data of 5265 patients: 2969 patients received phenytoin; 2296 received fosphenytoin, on the day of admission. One-to-one propensity score matching created 1871 matched pairs. No significant difference was found for vasopressor use on the day of admission (4.2 % vs. 4.4 %; odds ratio 1.07; 95 % confidence intervals 0.77-1.48; p = 0.69), or for mechanical ventilation on the day of admission, in-hospital mortality, length of hospital stay, or total hospitalization cost. Higher age, comorbidity of cardiac diseases and lower body mass index were associated significantly with increased vasopressor use, whereas the dose of phenytoin equivalents and the choice of fosphenytoin were not.

CONCLUSIONS

This nationwide observational study found no evidence that fosphenytoin provides higher efficacy or safety than phenytoin for treatment of status epilepticus in adults after diazepam. Age, cardiac disease and low body mass index were identified as independent risk factors for vasopressor use in both phenytoin and fosphenytoin.

Efficacy, Tolerability, and Safety of Concentrated Intranasal Midazolam Spray as Emergency Medication in Epilepsy Patients During Video-EEG Monitoring

BACKGROUND

An efficient, well tolerated, and safe emergency treatment with a rapid onset of action is needed to prevent seizure clusters and to terminate prolonged seizures and status epilepticus.

OBJECTIVES

This study aimed to examine the efficacy, tolerability, and safety of intranasal midazolam (in-MDZ) spray in clinical practice.

METHODS

In this retrospective, multicenter observational study, we evaluated all patients with peri-ictal application of in-MDZ during video-EEG monitoring at the epilepsy centers in Frankfurt and Marburg between 2 014 and 2017. For every patient, we analyzed the recurrence of any seizure or generalized tonic-clonic seizures after index seizures with and without in-MDZ administration. Treatment-emergent adverse events (TEAEs) were also evaluated.

RESULTS

In-MDZ was used in 243 patients with epilepsy (mean age 35.5 years; range 5-76 years; 46.5% female) for treatment of 459 seizures. A median dose of in-MDZ 5 mg (i.e., two puffs; range 2.5-15 mg) was administered within a median time from EEG seizure onset until in-MDZ application of 1.18 min [interquartile range (IQR) 1.27], while median time from clinical seizure onset until in-MDZ administration was 1.08 min (IQR 1.19). In-MDZ was given within 1 min after EEG seizure onset in 171 seizures. An intraindividual comparison of seizures with and without application of in-MDZ was feasible in 171 patients, demonstrating that in-MDZ reduced the occurrence of any (Cox proportional-hazard model p < 0.001) and generalized tonic-clonic seizure (Cox proportional-hazard model p = 0.0167) over a period of 24 h. The seizure-free timespan was doubled from a median of 5.0 h in controls to a median of 10.67 h after in-MDZ administration. We additionally clustered in-MDZ administrations for the 119 patients who received in-MDZ more than once, comparing them with the index cases without in-MDZ. Even when considering subsequent seizures with in-MDZ administration, a patient receiving in-MDZ is still half as likely to incur another seizure in the upcoming 24 h as compared with when the same patient does not receive in-MDZ (hazard ratio 0.50; 95% CI 0.42-0.60; p < 0.01). In-MDZ was well tolerated without major adverse events. The most common side effects were irritation of the nasal mucosa [37 cases (8.1%)], prolonged sedation [26 cases (5.7%)], and nausea and vomiting [12 cases (2.6%)]. A decline in oxygen saturation was measured after 78 seizures (17%).

CONCLUSION

We conclude that in-MDZ is a safe and efficient treatment option to prevent short-term recurrence of seizures. In-MDZ can be administered very quickly by trained staff within 1-2 min after seizure onset. No major cardiocirculatory or respiratory adverse events were observed.

HMGB1 Is a Therapeutic Target and Biomarker in Diazepam-Refractory Status Epilepticus with Wide Time Window

Status epilepticus (SE), a life-threatening neurologic emergency, is often poorly controlled by the current pharmacological therapeutics, which are limited to a narrow time window. Here, we investigated the proinflammatory cytokine high mobility group box-1 (HMGB1) as a candidate therapeutic target for diazepam (DZP)-refractory SE. We found that HMGB1 was upregulated and translocated rapidly during refractory SE period. Exogenous HMGB1 was sufficient to directly induce DZP-refractory SE in nonrefractory SE. Neutralization of HMGB1 with an anti-HMGB1 monoclonal antibody decreased the incidence of SE and alleviated the severity of seizure activity in DZP-refractory SE, which was mediated by a Toll-like receptor 4 (TLR4)-dependent pathway. Importantly, anti-HMGB1 mAb reversed DZP-refractory SE with a wide time window, extending the therapeutic window from 30 to 180 min. Furthermore, we found the upregulation of plasma HMGB1 level is closely correlated with the therapeutic response of anti-HMGB1 mAb in DZP-refractory SE. All these results indicated that HMGB1 is a potential therapeutic target and a useful predictive biomarker in DZP-refractory SE.

A coumarin-based turn-on chemosensor for selective detection of Zn(II) and application in live cell imaging

A 2-oxo-2H-chromene-3-carbohydrazide (CHB) was synthesized by the reaction of salicylaldehyde with diethyl malonate and hydrazine hydrate. The recognition behaviors of CHB to Zn²⁺ were investigated and the results showed that CHB exhibits well selectivity and sensitivity to Zn²⁺ with fast response in PBS (pH = 7.24, 60% DMF), the co-existed cations and anions could not interfere the recognition between CHB and Zn²⁺. Besides, the detection limit of CHB for Zn²⁺ was calculated to be 0.95 μM. Furthermore, DFT, EI-MS data and Job's plot were applied for determining the sensing mechanism of CHB with Zn²⁺ and the results showed that a type of 2:1 complex was formed between CHB and Zn²⁺ with the binding constant was 1.32 × 10⁴ M^-2. At last, probe CHB was successfully applied for the imaging of Zn²⁺ in living cells.

Changes in Real-world Practice Patterns of Antiepileptic Drugs for Status Epilepticus: A Nationwide Observational Study in Japan

Intravenous (i.v.) phenytoin/fosphenytoin is recommended as the second-line therapy of antiepileptic drugs in patients with status epilepticus (SE). i.v. Levetiracetam is regarded as an effective and safe equivalent with i.v. phenytoin/fosphenytoin. However, i.v. levetiracetam is not covered by public health insurance for SE in most countries. For this study, we performed the real-world practice pattern survey of antiepileptic drugs for status epilepticus using the nationwide inpatient database. We used the Japanese Diagnosis Procedure Combination inpatient database in Japan and identified all cases of emergency admission attributable to status epilepticus from March 2011 through March 2018. We described the patient characteristics and practice pattern of antiepileptic drugs. The analysis conducted for this study examined 31,472 cases. As the second-line therapy, the use of i.v. levetiracetam increased rapidly from 2016; 35% of cases received i.v. levetiracetam in 2017. By contrast, the use of i.v. phenytoin/fosphenytoin decreased from 2016. In-hospital mortality decreased year-by-year. No year-by-year change was observed for deaths within 24 h, length of hospital stay, drug-induced hepatitis, or drug-induced eruption. Although the use of levetiracetam for treatment of SE is not compensated by public health insurance in Japan, i.v. levetiracetam use is increasing dramatically as the second-line SE therapy. We propose that health insurance coverage be extended to include i.v. levetiracetam treatment for SE.

Management of status epilepticus in adults. Position paper of the Italian League against Epilepsy

Since the publication of the Italian League Against Epilepsy guidelines for the treatment of status epilepticus in 2006, advances in the field have ushered in improvements in the therapeutic arsenal. The present position paper provides neurologists, epileptologists, neurointensive care specialists, and emergency physicians with updated recommendations for the treatment of adult patients with status epilepticus. The aim is to standardize treatment recommendations in the care of this patient population.

Early polytherapy for benzodiazepine-refractory status epilepticus

The transition from single seizures to status epilepticus (SE) is associated with malaptive trafficking of synaptic gamma-aminobutyric acid (GABA_A) and glutamate receptors. The receptor trafficking hypothesis proposes that these changes are key events in the development of pharmacoresistance to antiepileptic drugs (AEDs) during SE, and that blocking their expression will help control drug-refractory SE (RSE). We tested this hypothesis in a model of SE induced by very high-dose lithium and pilocarpine (RSE), and in a model of SE induced by sc soman. Both models are refractory to benzodiazepines when treated 40 min after seizure onset. Our treatments aimed to correct the loss of inhibition because of SE-associated internalization of synaptic GABA_A receptors (GABA_AR), using an allosteric GABA_AR modulator, sometimes supplemented by an AED acting at a nonbenzodiazepine site. At the same time, we reduced excitation because of increased synaptic localization of NMDA and AMPA (?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and N-methyl-D-aspartate) receptors (NMDAR, AMPAR (?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor, N-methyl-D-aspartate receptors)) with an NMDAR channel blocker, since AMPAR changes are NMDAR-dependent. Treatment of RSE with combinations of the GABA_AR allosteric modulators midazolam or diazepam and the NMDAR antagonists dizocilpine or ketamine terminated RSE unresponsive to high-dose monotherapy. It also reduced RSE-associated neuronal injury, spatial memory deficits, and the occurrence of spontaneous recurrent seizures (SRS), tested several weeks after SE. Treatment of soman-induced SE also reduced seizures, behavioral deficits, and epileptogenesis. Addition of an AED further improved seizure outcome in both models. Three-dimensional isobolograms demonstrated positive cooperativity between midazolam, ketamine, and valproate, without any interaction between the toxicity of these drugs, so that the therapeutic index was increased by combination therapy. The midazolam-ketamine-valproate combination based on the receptor trafficking hypothesis was far more effective in stopping RSE than the midazolam-fosphenytoin-valproate combination inspired from clinical guidelines for the treatment of SE. Furthermore, sequential administration of midazolam, ketamine, and valproate was far less effective than simultaneous treatment with the same drugs at the same dose. These data suggest that treatment of RSE should be based at least in part on its pathophysiology. The search for a better treatment should focus on the cause of pharmacoresistance, which is loss of synaptic GABA_AR and gain of synaptic glutamate receptors. Both need to be treated. Monotherapy addresses only half the problem. Improved pharmacokinetics will not help pharmacoresistance because of loss of receptors. Waiting for one drug to fail before giving the second drugs gives pharmacoresistance time to develop. Future clinical trials should consider treating both the failure of inhibition and the runaway excitation which characterize RSE, and should include an early polytherapy arm. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

Neurobiology of organophosphate-induced seizures

This review summarizes the efforts of our laboratories to develop a mechanism-based therapy for the treatment of organophosphate (OP) nerve agent-induced seizures. Organophosphate poisoning can occur during warfare and terrorist attacks and in the civilian sphere because of intentional or unintentional poisoning. Persons exposed to OPs experience seizures. We developed animal models of OP poisoning and then evaluated the effects of OP on excitatory α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated glutamatergic neurotransmission in the hippocampus using patch-clamp electrophysiology. Organophosphate agents enhance glutamatergic transmission by enhancing neurotransmitter release. M1 muscarinic receptors mediate this effect, at least in part. Muscarinic receptors exert this action by inhibiting specific KCNQ2/3 potassium channels, which mediate the M-current. Flupirtine, a drug that open channels, is effective against OP-induced seizures. This article is part of the Special Issue"Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

Changes in excitatory and inhibitory receptor expression and network activity during induction and establishment of epilepsy in the rat Reduced Intensity Status Epilepticus (RISE) model

The RISE model is an effective system to study the underlying molecular and cellular mechanisms involved in the initiation and maintenance of epilepsy in vivo. Here we profiled the expression of excitatory and inhibitory neurotransmitter receptor subunits and synaptic scaffolding proteins in the hippocampus and temporal lobe and compared these changes with alterations in network activity at specific timepoints during epileptogenesis. Significant changes occurred in all of the ionotropic glutamate receptor subunits tested during epilepsy induction and progression and the profile of these changes differed between the hippocampus and temporal lobe. Notably, AMPAR subunits were dramatically decreased during the latent phase of epilepsy induction, matched by a profound decrease in the network response to kainate application in the hippocampus. Moreover, decreases in the GABAAβ3 subunit are consistent with a loss of inhibitory input contributing to the perturbation of excitatory/inhibitory balance and seizure generation. These data highlight the synaptic reorganisation that mediates the relative hypoexcitability prior to the manifestation of seizures and subsequent hyperexcitability when spontaneous seizures develop. These patterns of changes give new insight into the mechanisms underpinning epilepsy and provide a platform for future investigations targeting particular receptor subunits to reduce or prevent seizures.

Functional responses of the hippocampus to hyperexcitability depend on directed, neuron-specific KCNQ2 K+ channel plasticity

M-type (KCNQ2/3) K⁺ channels play dominant roles in regulation of active and passive neuronal discharge properties such as resting membrane potential, spike-frequency adaptation, and hyper-excitatory states. However, plasticity of M-channel expression and function in nongenetic forms of epileptogenesis are still not well understood. Using transgenic mice with an EGFP reporter to detect expression maps of KCNQ2 mRNA, we assayed hyperexcitability-induced alterations in KCNQ2 transcription across subregions of the hippocampus. Pilocarpine and pentylenetetrazol chemoconvulsant models of seizure induction were used, and brain tissue examined 48 hr later. We observed increases in KCNQ2 mRNA in CA1 and CA3 pyramidal neurons after chemoconvulsant-induced hyperexcitability at 48 hr, but no significant change was observed in dentate gyrus (DG) granule cells. Using chromogenic in situ hybridization assays, changes to KCNQ3 transcription were not detected after hyper-excitation challenge, but the results for KCNQ2 paralleled those using the KCNQ2-mRNA reporter mice. In mice 7 days after pilocarpine challenge, levels of KCNQ2 mRNA were similar in all regions to those from control mice. In brain-slice electrophysiology recordings, CA1 pyramidal neurons demonstrated increased M-current amplitudes 48 hr after hyperexcitability; however, there were no significant changes to DG granule cell M-current amplitude. Traumatic brain injury induced significantly greater KCNQ2 expression in the hippocampal hemisphere that was ipsilateral to the trauma. In vivo, after a secondary challenge with subconvulsant dose of pentylenetetrazole, control mice were susceptible to tonic-clonic seizures, whereas mice administered the M-channel opener retigabine were protected from such seizures. This study demonstrates that increased excitatory activity promotes KCNQ2 upregulation in the hippocampus in a cell-type specific manner. Such novel ion channel expressional plasticity may serve as a compensatory mechanism after a hyperexcitable event, at least in the short term. The upregulation described could be potentially leveraged in anticonvulsant enhancement of KCNQ2 channels as therapeutic target for preventing onset of epileptogenic seizures.

Comparison of intranasal versus intravenous midazolam for management of status epilepticus in dogs: A multi-center randomized parallel group clinical study

Background

The intranasal (IN) route for rapid drug administration in patients with brain disorders, including status epilepticus, has been investigated. Status epilepticus is an emergency, and the IN route offers a valuable alternative to other routes, especially when these fail.

Objectives

To compare IN versus IV midazolam (MDZ) at the same dosage (0.2 mg/kg) for controlling status epilepticus in dogs.

Animals

Client‐owned dogs (n = 44) with idiopathic epilepsy, structural epilepsy, or epilepsy of unknown origin manifesting as status epilepticus.

Methods

Randomized parallel group clinical trial. Patients were randomly allocated to the IN‐MDZ (n = 21) or IV‐MDZ (n = 23) group. Number of successfully treated cases (defined as seizure cessation within 5 minutes and lasting for ≥10 minutes), seizure cessation time, and adverse effects were recorded. Comparisons were performed using the Fisher's exact and Wilcoxon rank sum tests with statistical significance set at α < .05.

Results

IN‐MDZ and IV‐MDZ successfully stopped status epilepticus in 76% and 61% of cases, respectively (P = .34). The median seizure cessation time was 33 and 64 seconds for IN‐MDZ and IV‐MDZ, respectively (P = .63). When the time to place an IV catheter was taken into account, IN‐MDZ (100 seconds) was superior (P = .04) to IV‐MDZ (270 seconds). Sedation and ataxia were seen in 88% and 79% of the dogs treated with IN‐MDZ and IV‐MDZ, respectively.

Conclusions and Clinical Importance

Both routes are quick, safe, and effective for controlling status epilepticus. However, the IN route demonstrated superiority when the time needed to place an IV catheter was taken into account.

Divergent paths to seizure-like events

Much debate exists about how the brain transitions into an epileptic seizure. One source of confusion is that there are likely to be critical differences between experimental seizure models. To address this, we have compared the evolving activity patterns in two widely used in vitro models of epileptic discharges. Brain slices from young adult mice were prepared in the same way and bathed either in 0 Mg2+ or 100 µmol/L 4AP artificial cerebrospinal fluid. We have found that while local field potential recordings of epileptiform discharges in the two models appear broadly similar, patch-clamp analysis reveals an important difference in the relative degree of glutamatergic involvement. 4AP affects parvalbumin-expressing interneurons more than other cortical populations, destabilizing their resting state and inducing spontaneous bursting behavior. Consequently, the most prominent pattern of transient discharge ("interictal event") in this model is almost purely GABAergic, although the transition to seizure-like events (SLEs) involves pyramidal recruitment. In contrast, interictal discharges in 0 Mg2+ are only maintained by a very large glutamatergic component that also involves transient discharges of the interneurons. Seizure-like events in 0 Mg2+ have significantly higher power in the high gamma frequency band (60-120Hz) than these events do in 4AP, and are greatly delayed in onset by diazepam, unlike 4AP events. We, therefore, conclude that the 0 Mg2+ and 4AP models display fundamentally different levels of glutamatergic drive, demonstrating how ostensibly similar pathological discharges can arise from different sources. We contend that similar interpretative issues will also be relevant to clinical practice.

Genetically Encoded, Photostable Indicators to Image Dynamic Zn2+ Secretion of Pancreatic Islets

As an essential element for living organisms, zinc (Zn2+) exerts its biological functions both intracellularly and extracellularly. Previous studies have reported a number of genetically encoded Zn2+ indicators (GEZIs), which have been widely used to monitor Zn2+ in the cytosol and intracellular organelles. However, it is challenging to localize existing GEZIs to the extracellular space to detect secreted Zn2+. Herein, we report two photostable, green fluorescent protein (GFP) based indicators, ZIBG1 and ZIBG2, which respond to Zn2+ selectively and have affinities suited for detecting Zn2+ secretion from intracellular vesicles. In particular, ZIBG2 can be effectively targeted to the extracellular side of plasma membrane. We applied cell surface-localized ZIBG2 to monitor glucose-induced dynamic Zn2+ secretion from mouse insulinoma MIN6 cells and primary mouse and human pancreatic islets. Because Zn2+ is co-released with insulin from β-cells, the fluorescence of cell surface-localized ZIBG2 was shown to be a strong indicator for the functional potency of islets. Our work here has thus expanded the use of GEZIs to image dynamic Zn2+ secretion in live tissue. Because it is convenient to use genetically encoded indicators for expression over extended periods and for in vivo delivery, we envision future applications of ZIBG2 in development of induced β-cells or islets to advance cell replacement therapies for diabetes and in direct imaging of Zn2+ secretion dynamics in vivo.