Starting ketamine for neuroprotection earlier than its current use as an anesthetic/antiepileptic drug late in refractory status epilepticus

Ketamine ameliorates post-traumatic social avoidance by erasing the traumatic memory encoded in VTA-innervated BLA engram cells

Erasing traumatic memory during memory reconsolidation is a promising retrieval-extinction strategy for post-traumatic stress disorder (PTSD). Here, we developed an acute social defeat stress (SDS) mouse model with short-term and re-exposure-evoked long-term social avoidance. SDS-associated traumatic memories were identified to be stored in basolateral amygdala (BLA) engram cells. A single intraperitoneal administration of subanesthetic-dose ketamine within, but not beyond, the re-exposure time window significantly alleviates SDS-induced social avoidance, which reduces the activity and quantity of reactivated BLA engram cells. Furthermore, activation or inhibition of dopaminergic projections from the ventral tegmental area to the BLA effectively mimics or blocks the therapeutic effect of re-exposure with ketamine and is dopamine D2 receptor dependent. Single-cell RNA sequencing reveals that re-exposure with ketamine triggered significant changes in memory-related pathways in the BLA. Together, our research advances the understanding of how ketamine mitigates PTSD symptoms and offers promising avenues for developing more effective treatments for trauma-related disorders.

A systematic review and meta-analysis of ketamine in pediatric status epilepticus

OBJECTIVE

Status epilepticus (SE) is a common neurological medical emergency in the pediatric population, with 10%-40% of cases progressing to refractory SE (RSE), requiring treatment with anesthetic infusions. We present a systematic review and meta-analysis of the use of ketamine for the treatment of pediatric SE and its potential advantages over other anesthetic infusions.

METHODS

This review follows the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. Electronic databases, including PubMed, Cochrane Library, Ovid, Embase, and Google Scholar, were searched with the keywords "pediatrics," "status epilepticus," and "ketamine treatment." Randomized trials, prospective and retrospective cohort studies, and case reports were considered for inclusion.

RESULTS

Eighteen publications met the initial inclusion criteria. The 18 publications comprise 11 case reports, one nonconclusive clinical trial, two case series, and four retrospective cohorts. After excluding the case reports because of reporting bias, only the six case series and cohorts were included in the final analysis. There were 172 patients in the six included studies. The weighted age was 9.93 (SD = 10.29) years. The weighted maximum dose was 7.44 (SD = 9.39) mg/kg/h. SE cessation was attained in 51% (95% confidence interval = 43-59) of cases with the addition of ketamine. The heterogeneity was I2 = 0%, t2 = 0, χ2 (5) = 3.39 (p = .64).

SIGNIFICANCE

Pediatric RSE is difficult to treat, resulting in increased morbidity and mortality. Without strong recommendations and evidence regarding preferred agents, this review provides evidence that ketamine may be considered in managing SE in the pediatric population.

Update in Pediatric Neurocritical Care: What a Neurologist Caring for Critically Ill Children Needs to Know

Currently nearly one-quarter of admissions to pediatric intensive care units (PICUs) worldwide are for neurocritical care diagnoses that are associated with significant morbidity and mortality. Pediatric neurocritical care is a rapidly evolving field with unique challenges due to not only age-related responses to primary neurologic insults and their treatments but also the rarity of pediatric neurocritical care conditions at any given institution. The structure of pediatric neurocritical care services therefore is most commonly a collaborative model where critical care medicine physicians coordinate care and are supported by a multidisciplinary team of pediatric subspecialists, including neurologists. While pediatric neurocritical care lies at the intersection between critical care and the neurosciences, this narrative review focuses on the most common clinical scenarios encountered by pediatric neurologists as consultants in the PICU and synthesizes the recent evidence, best practices, and ongoing research in these cases. We provide an in-depth review of (1) the evaluation and management of abnormal movements (seizures/status epilepticus and status dystonicus); (2) acute weakness and paralysis (focusing on pediatric stroke and select pediatric neuroimmune conditions); (3) neuromonitoring modalities using a pathophysiology-driven approach; (4) neuroprotective strategies for which there is evidence (e.g., pediatric severe traumatic brain injury, post-cardiac arrest care, and ischemic stroke and hemorrhagic stroke); and (5) best practices for neuroprognostication in pediatric traumatic brain injury, cardiac arrest, and disorders of consciousness, with highlights of the 2023 updates on Brain Death/Death by Neurological Criteria. Our review of the current state of pediatric neurocritical care from the viewpoint of what a pediatric neurologist in the PICU needs to know is intended to improve knowledge for providers at the bedside with the goal of better patient care and outcomes.

Ketamine in the treatment of refractory and super-refractory status epilepticus: Experience from two centres

PURPOSE

There is insufficient evidence on the management of refractory status epilepticus (RSE) and super-RSE (SRSE). Ketamine is a N-methyl-d-aspartate receptor antagonist in the treatment of these entities. Our objectives were to study the effectiveness and safety of ketamine in the treatment of adult patients with RSE and SRSE, to determine the factors that can influence the response to ketamine, and to explore its use in patients without mechanical ventilation.

METHODS

Adult patients who had received intravenous ketamine for the treatment of RSE or SRSE at Hospital Universitario Clínico San Carlos (Madrid, Spain) or Hospital Universitari Vall d'Hebron (Barcelona, Spain) from 2017 to 2023 were retrospectively analysed.

RESULTS

This study included 58 adult patients, mean (standard deviation) age 60.2 (15.7) years, of whom 41 (70.7 %) were male; 33 (56.9 %) patients responded to ketamine without recurrence, with a low rate of adverse effects (8.6 %). The presence of SRSE at the time of ketamine initiation (OR 0.287, p = 0.028) and the time elapsed between status epilepticus onset and ketamine administration (OR 0.991, p = 0.034) were associated with worse response to ketamine. Patients treated without mechanical ventilation had similar rates of response without recurrence (62.5% vs 56.9 %) and lower mortality (37.5% vs 53.5 %) compared to the overall group.

CONCLUSION

Ketamine is an effective drug with few adverse effects. Prompt administration should be considered in patients with RSE requiring anaesthesia, in patients with SRSE, and in patients with RSE who do not respond to standard antiseizure drugs and in whom mechanical ventilation is not advised.

Ketamine for Super-Refractory Status Epilepticus in Palliative Care. A Case Report and Review of the Literature

We report a case of super refractory status epilepticus uncontrolled by multiple anti-seizure medications in an individual with acute liver failure due to hepatic cirrhosis and an obstructive ileocecal mass plus multiple bilateral lung lesions presumed to be metastatic. A ketamine infusion was initiated late in his hospitalization which eliminated the convulsive seizures in less than an hour. The abatement of convulsive seizures allowed his grieving wife to return to her husband's bedside to witness the withdrawal of life sustaining treatment and be present during the final 24 hours of his life. We review the medical literature on the role of Intravenous (IV) Ketamine in the treatment of super refractory status epilepticus.

Low-dose ketamine improves animals' locomotor activity and decreases brain oxidative stress and inflammation in ammonia-induced neurotoxicity

Ammonium ion (NH4 + ) is the major suspected molecule responsible for neurological complications of hepatic encephalopathy (HE). No specific pharmacological action for NH4 + -induced brain injury exists so far. Excitotoxicity is a well-known phenomenon in the brain of hyperammonemic cases. The hyperactivation of the N-Methyl- d-aspartate (NMDA) receptors by agents such as glutamate, an NH4 + metabolite, could cause excitotoxicity. Excitotoxicity is connected with events such as oxidative stress and neuroinflammation. Hence, utilizing NMDA receptor antagonists could prevent neurological complications of NH4 + neurotoxicity. In the current study, C57BL6/J mice received acetaminophen (APAP; 800 mg/kg, i.p) to induce HE. Hyperammonemic animals were treated with ketamine (0.25, 0.5, and 1 mg/kg, s.c) as an NMDA receptor antagonist. Animals' brain and plasma levels of NH4 + were dramatically high, and animals' locomotor activities were disturbed. Moreover, several markers of oxidative stress were significantly increased in the brain. A significant increase in brain tissue levels of TNF-α, IL-6, and IL-1β was also detected in hyperammonemic animals. It was found that ketamine significantly normalized animals' locomotor activity, improved biomarkers of oxidative stress, and decreased proinflammatory cytokines. The effects of ketamine on oxidative stress biomarkers and inflammation seem to play a key role in its neuroprotective mechanisms in the current study.

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.

Ketamine as advanced second-line treatment in benzodiazepine-refractory convulsive status epilepticus in children

Status epilepticus (SE) is one of the most common neurological emergencies in children. To date, there is no definitive evidence to guide treatment of SE refractory to benzodiazepines. The main objectives of treatment protocols are to expedite therapeutic decisions and to use fast- and short-acting medications without significant adverse effects. Protocols differ among institutions, and most frequently valproate, phenytoin, and levetiracetam are used as second-line treatment. After failure of first- and second-line medications, admission to the intensive care unit and continuous infusion of anesthetics are usually indicated. Ketamine is a noncompetitive N-methyl-D-aspartate receptor antagonist that has been safely used for the treatment of refractory SE in adults and children. In animal models of SE, ketamine demonstrated antiepileptic and neuroprotective properties and synergistic effects with other antiseizure medications. We reviewed the literature to demonstrate the potential role of ketamine as an advanced second-line agent in the treatment of SE. Pharmacological targets, pathophysiology of SE, and the receptor trafficking hypothesis are reviewed and presented. The pharmacology of ketamine is outlined with related properties, advantages, and side effects. We summarize the most recent and relevant publications on experimental and clinical studies on ketamine in SE. Key expert opinion is also reported. Considering the current knowledge on SE pathophysiology, early sequential polytherapy should include ketamine for its wide range of positive assets. Future research and clinical trials on SE pharmacotherapy should focus on the role of ketamine as second-line medication.

Safety and Tolerability of the Acute Ketamine Treatment in Treatment-Resistant Depression: Focus on Comorbidities Interplay with Dissociation and Psychomimetic Symptoms

There is evidence for ketamine use in treatment-resistant depression (TRD). Several safety concerns arise regarding adverse drug reactions in specific subpopulations. The aim of this study was to investigate the safety of intravenous ketamine treatment in relation to dissociative and psychotic measures in TRD inpatients with Major Depressive Disorder (MDD) and Bipolar depression (BP) with comorbidities. In total, 49 inpatients with MDD or BP were treated with ketamine following the registered naturalistic observational protocol in a tertiary reference unit for mood disorders (NCT04226963). This dataset represents an intermittent analysis of an observational study performed for interim modeling of observational learning. The observations were applied to the inhomogeneous TRD population in a single site with no blinding and were limited to acute administration. The presence of epilepsy was significantly associated with an elevation in the BPRS over time (p = 0.008). Psychotic symptomatology with BPRS scores for comorbid conditions excluding epilepsy turned out to be insignificant (p = 0.198) regardless of the diagnosis. However, for a subgroup of patients with epilepsy (n = 6), a substantial fluctuation was seen across all administrations in the time course of the study. The study results contribute to the literature on the safety and tolerability profile of CNS adverse drug reactions in short-term treatment with intravenous ketamine as an add-on intervention to current standard-of-care psychotropic medication in TRD-MDD and TRD-BP inpatients with comorbidities. The careful consideration of comorbidities and concomitant medication is needed with ketamine administration along with close-clinical supervision at every visit.

Ketamine administration in idiopathic epileptic and healthy control dogs: Can we detect differences in brain metabolite response with spectroscopy?

Introduction

In recent years ketamine has increasingly become the focus of multimodal emergency management for epileptic seizures. However, little is known about the effect of ketamine on brain metabolites in epileptic patients. Magnetic resonance spectroscopy (MRS) is a non-invasive technique to estimate brain metabolites in vivo. Our aim was to measure the effect of ketamine on thalamic metabolites in idiopathic epileptic (IE) dogs using 3 Tesla MRS. We hypothesized that ketamine would increase the glutamine-glutamate (GLX)/creatine ratio in epileptic dogs with and without antiseizure drug treatment, but not in control dogs. Furthermore, we hypothesized that no different responses after ketamine administration in other measured brain metabolite ratios between the different groups would be detected.

Methods

In this controlled prospective experimental trial IE dogs with or without antiseizure drug treatment and healthy client-owned relatives of the breeds Border Collie and Greater Swiss Mountain Dog, were included. After sedation with butorphanol, induction with propofol and maintenance with sevoflurane in oxygen and air, a single voxel MRS at the level of the thalamus was performed before and 2 min after intravenous administration of 1 mg/kg ketamine. An automated data processing spectral fitting linear combination model algorithm was used to estimate all commonly measured metabolite ratios. A mixed ANOVA with the independent variables ketamine administration and group allocation was performed for all measured metabolites. A p < 0.05 was considered statistically significant.

Results

Twelve healthy control dogs, 10 untreated IE and 12 treated IE dogs were included. No significant effects for GLX/creatine were found. However, increased glucose/creatine ratios were found (p < 0.001) with no effect of group allocation. Furthermore, increases in the GABA/creatine ratio were found in IEU dogs.

Discussion

MRS was able to detect changes in metabolite/creatine ratios after intravenous administration of 1 mg/kg ketamine in dogs and no evidence was found that excitatory effects are induced in the thalamus. Although it is beyond the scope of this study to investigate the antiseizure potential of ketamine in dogs, results of this research suggest that the effect of ketamine on the brain metabolites could be dependent on the concentrations of brain metabolites before administration.

Antidepressant Drugs for Seizures and Epilepsy: Where do we Stand?

People with epilepsy (PWE) are more likely to develop depression and both these complex chronic diseases greatly affect health-related quality of life (QOL). This comorbidity contributes to the deterioration of the QOL further than increasing the severity of epilepsy worsening prognosis. Strong scientific evidence suggests the presence of shared pathogenic mechanisms. The correct identification and management of these factors are crucial in order to improve patients' QOL. This review article discusses recent original research on the most common pathogenic mechanisms of depression in PWE and highlights the effects of antidepressant drugs (ADs) against seizures in PWE and animal models of seizures and epilepsy. Newer ADs, such as selective serotonin reuptake inhibitors (SRRI) or serotonin-noradrenaline reuptake inhibitors (SNRI), particularly sertraline, citalopram, mirtazapine, reboxetine, paroxetine, fluoxetine, escitalopram, fluvoxamine, venlafaxine, duloxetine may lead to improvements in epilepsy severity whereas the use of older tricyclic antidepressant (TCAs) can increase the occurrence of seizures. Most of the data demonstrate the acute effects of ADs in animal models of epilepsy while there is a limited number of studies about the chronic antidepressant effects in epilepsy and epileptogenesis or on clinical efficacy. Much longer treatments are needed in order to validate the effectiveness of these new alternatives in the treatment and the development of epilepsy, while further clinical studies with appropriate protocols are warranted in order to understand the real potential contribution of these drugs in the management of PWE (besides their effects on mood).

Immediate and progressive neurological damage after electrical injury: A pediatric case report

BACKGROUND

An electrical injury can cause multiple consequences, especially to the nervous system, both peripheral and central. Such consequences may present immediately as well as later on.

AIMS OF THE STUDY

To report on a case of a 5-year-old boy with focal refractory status epilepticus after an electrical injury.

METHODS

Clinical history, electroencephalography, neuroimaging, and laboratory data of a patient admitted to our emergency department.

RESULTS

A 5-year-old male received an electrical shock by contact with an alternating current source after coming out of the pool. When reaching our emergency department, focal seizures was observed in the same site affected by the electrical insult, with progressive structural changes in the related brain area. In the days after, his neurological conditions dramatically evolved leading to brain death.

CONCLUSIONS

Based on our knowledge, this is the first report on refractory status epilepticus in a child after electrical injury. The possible underlying pathogenetic mechanisms are not yet clear.

Management and prognosis of pediatric status epilepticus

Background

Pediatric status epilepticus is a neurological emergency with the potential for severe developmental and neurological consequences. Prompt diagnosis and management are necessary.

Objectives

To outline the existing best available evidence for managing pediatric and neonatal status epilepticus, in the light of emerging randomized controlled studies. We also focus on short and long-term prognoses.

Materials and methods

This is a systematic overview of the existing literature.

Results

Status epilepticus, its treatment, and prognosis are usually based on the continuation of seizure activity at 5 and 30 min. Refractory and super-refractory status epilepticus further complicates management and requires continuous EEG monitoring with regular reassessment and adjustment of therapy. Benzodiazepines have been accepted as the first line of treatment on the basis of reasonable evidence. Emerging randomized controlled trials demonstrate equal efficacy for parenterally administered phenytoin, levetiracetam, and valproic acid as second-line agents. Beyond this, the evidence for third-line options is sparse. However, encouraging evidence for midazolam and ketamine exists with further data required for immunological, dietary, and surgical interventions.

Conclusion

Our overview of the management of pediatric and neonatal status epilepticus based on available evidence emphasizes the need for evidence-based guidelines to manage status epilepticus that fails to respond to second-line treatment.

Ketamine for Management of Neonatal and Pediatric Refractory Status Epilepticus

BACKGROUND AND OBJECTIVES

Few data are available regarding the use of anesthetic infusions for refractory status epilepticus (RSE) in children and neonates, and ketamine use is increasing despite limited data. We aimed to describe the impact of ketamine for RSE in children and neonates.

METHODS

Retrospective single-center cohort study of consecutive patients admitted to the intensive care units of a quaternary care children's hospital treated with ketamine infusion for RSE.

RESULTS

Sixty-nine patients were treated with a ketamine infusion for RSE. The median age at onset of RSE was 0.7 years (interquartile range 0.15-7.2), and the cohort included 13 (19%) neonates. Three patients (4%) had adverse events requiring intervention during or within 12 hours of ketamine administration, including hypertension in 2 patients and delirium in 1 patient. Ketamine infusion was followed by seizure termination in 32 patients (46%), seizure reduction in 19 patients (28%), and no change in 18 patients (26%).

DISCUSSION

Ketamine administration was associated with few adverse events, and seizures often terminated or improved after ketamine administration. Further data are needed comparing first-line and subsequent anesthetic medications for treatment of pediatric and neonatal RSE.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence on the therapeutic utility of ketamine for treatment of RSE in children and neonates.

Ketamine and Its Emergence in the Field of Neurology

The quest for a safe and effective anesthetic medication in the mid-20th century led to the discovery of CI-581, which was later named ketamine. Ketamine was labeled a “dissociative anesthetic” due to the state of sensory deprivation that it induces in the subjects receiving it. Although it enjoyed widespread use at the beginning of the Vietnam war, its use rapidly waned due to its psychedelic effect and it became more popular as a recreational drug, and in the field of veterinary medicine. However, as we gained more knowledge about its multiple sites of action, it has reemerged as a useful anesthetic/analgesic agent. In the last decade, the field of neurology has witnessed the growing use of ketamine for the treatment of several neurological conditions including migraine, status epilepticus, stroke, and traumatic brain injury (TBI). Ketamine acts primarily as a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist. The binding of ketamine to NMDA receptors leads to decreased frequency and duration of Ca⁺² channel opening and thus inhibits glutaminergic transmission. This mechanism has proven to be neuroprotective in several neurological conditions. Ketamine does not increase intracranial pressure (ICP), and it maintains cerebral perfusion pressure (CPP) by increasing cerebral blood flow. Ketamine has also been shown to inhibit massive slow waves of neurological depolarizations called cortical spreading depolarizations (CSD), usually seen during acute neurological injury and are responsible for further neurological deterioration. Unlike other anesthetic agents, ketamine does not cause cardiac or respiratory suppression. All these favorable mechanisms and cerebral/hemodynamic actions have led to increased interest among clinicians and researchers regarding the novel uses of ketamine. This review will focus on the use of ketamine for various neurological indications.

Ketamine; history and role in anesthetic pharmacology

Ketamine (Ket) was developed in 1962 as a less hallucinogenic and shorter acting agent than phencyclidine. It was given to humans for the first time in 1964. However, Ket produces several adverse reactions such as raised intracranial and blood pressures along with seizures, and patients still show low acceptance due to hallucinations. As new volatile and intravenous anesthetic agents with good emergence and favorable side effect profiles were developed, Ket use markedly decreased. In the 1990s, as the ultrashort-acting opioid remifentanil was developed, high dose opioid could be used to reduce surgical stress in highly invasive procedures. However, high dose opioids can produce hyperalgesia and acute tolerance. As Ket can exert anti-hyperalgesic actions, the clinical use of low dose Ket has been reconsidered. Other beneficial effects of Ket such as; analgesia, anti-shock in hemorrhagic and septic insults, anti-inflammatory effects, anti-tumor effects, brain and spinal cord neuroprotection, and bronchodilation, have all been reported. Moreover, this anesthetic agent at low dose has been recently recognized to possess anti-depressive actions. This diverse profile extends Ket far beyond anesthesia practice and the operating room.

Early Combination Therapy of Ketamine and Midazolam in Patients with Refractory Status Epilepticus in Hemodynamic Unstable State

The use of anesthetics is inevitable to suppress seizure activity in refractory status epilepticus (RSE). Hypotension, which is a critical side effect observed when treating RSE using a higher dosage of anesthetics that enhance γ-aminobutyric acid (GABA) activity, often requires vasopressor agents. Concomitant treatment with N-methyl-D-aspartate (NMDA) receptor antagonists, such as ketamine, could be effective in prolonged refractory SE, while maintaining stable blood pressure owing to the blockage of catecholamine reuptake in the systemic circulation. We report two cases of patients who had RSE with hemodynamic instability treated promptly with an early combination of ketamine and low-dose midazolam. The combination treatment effectively suppressed epileptic discharge with less hemodynamic side effects; moreover, a low dose of midazolam was required when combined with ketamine therapy. The initial combination of a third-line therapy that blocks NMDA receptors with enhanced GABAergic activity could be useful in RSE. Further studies are necessary in many variable etiologies of SE.

Super-Refractory Status Epilepticus in Children: A Retrospective Cohort Study

OBJECTIVES

To characterize the pediatric super-refractory status epilepticus population by describing treatment variability in super-refractory status epilepticus patients and comparing relevant clinical characteristics, including outcomes, between super-refractory status epilepticus, and nonsuper-refractory status epilepticus patients.

DESIGN

Retrospective cohort study with prospectively collected data between June 2011 and January 2019.

SETTING

Seventeen academic hospitals in the United States.

PATIENTS

We included patients 1 month to 21 years old presenting with convulsive refractory status epilepticus. We defined super-refractory status epilepticus as continuous or intermittent seizures lasting greater than or equal to 24 hours following initiation of continuous infusion and divided the cohort into super-refractory status epilepticus and nonsuper-refractory status epilepticus groups.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We identified 281 patients (157 males) with a median age of 4.1 years (1.3-9.5 yr), including 31 super-refractory status epilepticus patients. Compared with nonsuper-refractory status epilepticus group, super-refractory status epilepticus patients had delayed initiation of first nonbenzodiazepine-antiseizure medication (149 min [55-491.5 min] vs 62 min [33.3-120.8 min]; p = 0.030) and of continuous infusion (495 min [177.5-1,255 min] vs 150 min [90-318.5 min]; p = 0.003); prolonged seizure duration (120 hr [58-368 hr] vs 3 hr [1.4-5.9 hr]; p < 0.001) and length of ICU stay (17 d [9.5-40 d] vs [1.8-8.8 d]; p < 0.001); more medical complications (18/31 [58.1%] vs 55/250 [22.2%] patients; p < 0.001); lower return to baseline function (7/31 [22.6%] vs 182/250 [73.4%] patients; p < 0.001); and higher mortality (4/31 [12.9%] vs 5/250 [2%]; p = 0.010). Within the super-refractory status epilepticus group, status epilepticus resolution was attained with a single continuous infusion in 15 of 31 patients (48.4%), two in 10 of 31 (32.3%), and three or more in six of 31 (19.4%). Most super-refractory status epilepticus patients (30/31, 96.8%) received midazolam as first choice. About 17 of 31 patients (54.8%) received additional treatments.

CONCLUSIONS

Super-refractory status epilepticus patients had delayed initiation of nonbenzodiazepine antiseizure medication treatment, higher number of medical complications and mortality, and lower return to neurologic baseline than nonsuper-refractory status epilepticus patients, although these associations were not adjusted for potential confounders. Treatment approaches following the first continuous infusion were heterogeneous, reflecting limited information to guide clinical decision-making in super-refractory status epilepticus.

Ketamine: Neuroprotective or Neurotoxic?

Ketamine, a non-competitive N-methyl-D-aspartate receptor (NMDAR) antagonist, has been employed clinically as an intravenous anesthetic since the 1970s. More recently, ketamine has received attention for its rapid antidepressant effects and is actively being explored as a treatment for a wide range of neuropsychiatric syndromes. In model systems, ketamine appears to display a combination of neurotoxic and neuroprotective properties that are context dependent. At anesthetic doses applied during neurodevelopmental windows, ketamine contributes to inflammation, autophagy, apoptosis, and enhances levels of reactive oxygen species. At the same time, subanesthetic dose ketamine is a powerful activator of multiple parallel neurotrophic signaling cascades with neuroprotective actions that are not always NMDAR-dependent. Here, we summarize results from an array of preclinical studies that highlight a complex landscape of intracellular signaling pathways modulated by ketamine and juxtapose the somewhat contrasting neuroprotective and neurotoxic features of this drug.

Comeback of ketamine: resurfacing facts and dispelling myths

Initially known as CI-581, ketamine was first synthesized in 1962 as a replacement from phencyclidine. It has since been used as an anesthetic and analgesic. In addition, it has bronchodilating, sedative, and amnestic properties, preserving airway reflexes and sympathetic nervous system tone. Since the discovery of ketamine, it has been a major topic of discussion due to controversies regarding its usage in particular sets of patients. In the past 50 years, despite its potential benefits, it is not commonly used because of concerns of "emergence phenomenon," its use as a substance of abuse, and its systemic side effects. Since 2012, three World Health Organization reviews on ketamine have addressed its international control. Researchers have been studying this wonder drug for a decade worldwide. Many myths of ketamine regarding emergence phenomenon and its use in traumatic brain injury and open eye injury have been disproved in recent times. It is becoming popular in pre-hospital settings, critical care, emergency medicine, low-dose acute pain services, and adjuvant in regional anesthesia techniques. This review highlights the current consensus on the various applications of ketamine in the literature.

A review of the clinical applications of ketamine in pediatric oncology

Ketamine is a dissociative anesthetic agent with excellent analgesic properties and a favorable safety profile. The feasibility and efficacy of various routes of administration have been established, including intravenous (IV), intramuscular (IM), oral, intranasal, rectal, and transdermal routes. The advent of newer anesthetic agents has led to a decline in the use of ketamine as an anesthetic, but its utility in short-term sedation and analgesia has expanded. Its value for chronic pain management in children with cancer is being increasingly recognized but requires more evidence. The use of topical ketamine is largely in investigational stages. Medical use of ketamine is, to a great extent, free from significant long-term neurological side effects. The objective of this review is to provide a brief account of the pharmacology of ketamine and primarily focus on the clinical applications of ketamine in pediatric oncology.

The Need to Intervene Before Time Point 2: Evidence From Clinical and Animal Data That Status Epilepticus Damages the Brain

Status epilepticus, a condition characterized by abnormally prolonged seizures, has the potential to cause irreversible, structural or functional, injury to the brain. Unfavorable consequences of these seizures include mortality, the risk of developing epilepsy, and cognitive impairment. We highlight key findings of clinical and laboratory studies that have provided insights into aspects of cell death, and anatomical and functional alterations triggered by status epilepticus that support the need to intervene before time point 2, the time after which the risk of these long-term consequences increases.

Treatment of Refractory Convulsive Status Epilepticus: A Comprehensive Review by the American Epilepsy Society Treatments Committee

Purpose:

Established tonic–clonic status epilepticus (SE) does not stop in one-third of patients when treated with an intravenous (IV) benzodiazepine bolus followed by a loading dose of a second antiseizure medication (ASM). These patients have refractory status epilepticus (RSE) and a high risk of morbidity and death. For patients with convulsive refractory status epilepticus (CRSE), we sought to determine the strength of evidence for 8 parenteral ASMs used as third-line treatment in stopping clinical CRSE.

Methods:

A structured literature search (MEDLINE, Embase, CENTRAL, CINAHL) was performed to identify original studies on the treatment of CRSE in children and adults using IV brivaracetam, ketamine, lacosamide, levetiracetam (LEV), midazolam (MDZ), pentobarbital (PTB; and thiopental), propofol (PRO), and valproic acid (VPA). Adrenocorticotropic hormone (ACTH), corticosteroids, intravenous immunoglobulin (IVIg), magnesium sulfate, and pyridoxine were added to determine the effectiveness in treating hard-to-control seizures in special circumstances. Studies were evaluated by predefined criteria and were classified by strength of evidence in stopping clinical CRSE (either as the last ASM added or compared to another ASM) according to the 2017 American Academy of Neurology process.

Results:

No studies exist on the use of ACTH, corticosteroids, or IVIg for the treatment of CRSE. Small series and case reports exist on the use of these agents in the treatment of RSE of suspected immune etiology, severe epileptic encephalopathies, and rare epilepsy syndromes. For adults with CRSE, insufficient evidence exists on the effectiveness of brivaracetam (level U; 4 class IV studies). For children and adults with CRSE, insufficient evidence exists on the effectiveness of ketamine (level U; 25 class IV studies). For children and adults with CRSE, it is possible that lacosamide is effective at stopping RSE (level C; 2 class III, 14 class IV studies). For children with CRSE, insufficient evidence exists that LEV and VPA are equally effective (level U, 1 class III study). For adults with CRSE, insufficient evidence exists to support the effectiveness of LEV (level U; 2 class IV studies). Magnesium sulfate may be effective in the treatment of eclampsia, but there are only case reports of its use for CRSE. For children with CRSE, insufficient evidence exists to support either that MDZ and diazepam infusions are equally effective (level U; 1 class III study) or that MDZ infusion and PTB are equally effective (level U; 1 class III study). For adults with CRSE, insufficient evidence exists to support either that MDZ infusion and PRO are equally effective (level U; 1 class III study) or that low-dose and high-dose MDZ infusions are equally effective (level U; 1 class III study). For children and adults with CRSE, insufficient evidence exists to support that MDZ is effective as the last drug added (level U; 29 class IV studies). For adults with CRSE, insufficient evidence exists to support that PTB and PRO are equally effective (level U; 1 class III study). For adults and children with CRSE, insufficient evidence exists to support that PTB is effective as the last ASM added (level U; 42 class IV studies). For CRSE, insufficient evidence exists to support that PRO is effective as the last ASM used (level U; 26 class IV studies). No pediatric-only studies exist on the use of PRO for CRSE, and many guidelines do not recommend its use in children aged <16 years. Pyridoxine-dependent and pyridoxine-responsive epilepsies should be considered in children presenting between birth and age 3 years with refractory seizures and no imaging lesion or other acquired cause of seizures. For children with CRSE, insufficient evidence exists that VPA and diazepam infusion are equally effective (level U, 1 class III study). No class I to III studies have been reported in adults treated with VPA for CRSE. In comparison, for children and adults with established convulsive SE (ie, not RSE), after an initial benzodiazepine, it is likely that loading doses of LEV 60 mg/kg, VPA 40 mg/kg, and fosphenytoin 20 mg PE/kg are equally effective at stopping SE (level B, 1 class I study).

Conclusions:

Mostly insufficient evidence exists on the efficacy of stopping clinical CRSE using brivaracetam, lacosamide, LEV, valproate, ketamine, MDZ, PTB, and PRO either as the last ASM or compared to others of these drugs. Adrenocorticotropic hormone, IVIg, corticosteroids, magnesium sulfate, and pyridoxine have been used in special situations but have not been studied for CRSE. For the treatment of established convulsive SE (ie, not RSE), LEV, VPA, and fosphenytoin are likely equally effective, but whether this is also true for CRSE is unknown. Triple-masked, randomized controlled trials are needed to compare the effectiveness of parenteral anesthetizing and nonanesthetizing ASMs in the treatment of CRSE.

Multifocal Stroke Complicating Anti-NMDA Receptor Encephalitis

Anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) is an autoimmune form of encephalitis, first described in 2005 and now recognized as among the more common causes of encephalitis. While NMDARE can result in permanent neurologic deficits or even mortality, the prognosis in children is generally more favorable; 75–85% of children and teenagers achieve a full or substantial recovery. We describe here a preadolescent female, whose course of NMDARE was complicated by a unilateral stroke, resulting in permanent deficits. The imaging characteristics suggest a vascular (thrombotic) etiology. To our knowledge, this is the first report of stroke in the setting of NMDARE.

Phenobarbital as alternate anticonvulsant for organophosphate-induced benzodiazepine-refractory status epilepticus and neuronal injury

Objective

Organophosphates (OPs) such as diisopropylfluorophosphate (DFP) and soman are lethal chemical agents that can produce seizures, refractory status epilepticus (SE), and brain damage. There are few optimal treatments for late or refractory SE. Phenobarbital is a second‐line drug for SE, usually after lorazepam, diazepam, or midazolam have failed to stop SE. Practically, 40 minutes or less is often necessary for first responders to arrive and assist in a chemical incident. However, it remains unclear whether administration of phenobarbital 40 minutes after OP intoxication is still effective. Here, we investigated the efficacy of phenobarbital treatment at 40 minutes postexposure to OP intoxication.

Methods

Acute refractory SE was induced in rats by DFP injection as per a standard paradigm. After 40 minutes, subjects were given phenobarbital intramuscularly (30‐100 mg/kg) and progression of seizure activity was monitored by video‐EEG recording. The extent of brain damage was assessed 3 days after DFP injections by neuropathology analysis of neurodegeneration and neuronal injury by unbiased stereology.

Results

Phenobarbital produced a dose‐dependent seizure protection. A substantial decrease in SE was evident at 30 and 60 mg/kg, and a complete seizure termination was noted at 100 mg/kg within 40 minutes after treatment. Neuropathology findings showed significant neuroprotection in 100 mg/kg cohorts in brain regions associated with SE. Although higher doses resulted in greater protection against refractory SE and neuronal damage, they did not positively correlate with improved survival rate. Moreover, phenobarbital caused serious adverse effects including anesthetic or comatose state and even death.

Significance

Phenobarbital appears as an alternate anticonvulsant for OP‐induced refractive SE in hospital settings. A careful risk‐benefit analysis is required because of negative outcomes on survival and cardio‐respiratory function. However, the need for sophisticated support and critical monitoring in hospital may preclude its use as medical countermeasure in mass casualty situations.

A Review of Nonanesthetic Uses of Ketamine

Ketamine, a nonselective NMDA receptor antagonist, is used widely in medicine as an anesthetic agent. However, ketamine's mechanisms of action lead to widespread physiological effects, some of which are now coming to the forefront of research for the treatment of diverse medical disorders. This paper aims at reviewing recent data on key nonanesthetic uses of ketamine in the current literature. MEDLINE, CINAHL, and Google Scholar databases were queried to find articles related to ketamine in the treatment of depression, pain syndromes including acute pain, chronic pain, and headache, neurologic applications including neuroprotection and seizures, and alcohol and substance use disorders. It can be concluded that ketamine has a potential role in the treatment of all of these conditions. However, research in this area is still in its early stages, and larger studies are required to evaluate ketamine's efficacy for nonanesthetic purposes in the general population.