Management of refractory status epilepticus in adults: still more questions than answers

Commentary on ‘propofol versus thiopental sodium for the treatment of refractory status epilepticus—still no answer’

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as:Prabhakar H, Bindra A, Singh GP, Kalaivani M. Propofol versus thiopental sodium for the treatment ofrefractory status epilepticus. Cochrane Database of Systematic Reviews 2012, Issue 8. Art. No.: CD009202.DOI: 10.1002/14651858.CD009202.pub2.

High-dose midazolam infusion for refractory status epilepticus

OBJECTIVE

This study compares 2 treatment protocols allowing low vs high continuous IV midazolam (cIV-MDZ) doses.

METHODS

We compared adults with refractory status epilepticus treated with a protocol allowing for high-dose cIV-MDZ (n = 100; 2002-2011) with those treated with the previous lower-dose cIV-MDZ (n = 29; 1996-2000). We collected data on baseline characteristics, cIV-MDZ doses, seizure control, hospital course, and outcome.

RESULTS

Median maximum cIV-MDZ dose was 0.4 mg/kg/h (interquartile range [IQR] 0.2, 1.0) for the high-dose group and 0.2 mg/kg/h (IQR 0.1, 0.3) for the low-dose group (p < 0.001) with similar duration of infusion. Median time from status epilepticus onset to cIV-MDZ start was 1 day (IQR 1, 3) for the high-dose group and 2 days (IQR 1, 5) for the low-dose group (p = 0.016). "Withdrawal seizures" (occurring within 48 hours of discontinuation of cIV-MDZ) were less frequent in the high-dose group (15% vs 64%, odds ratio 0.10, 95% confidence interval 0.03-0.27). "Ultimate cIV-MDZ failure" (patients requiring change to a different cIV antiepileptic medication) and hospital complications were not different between groups. Hypotension was more frequent with higher cIV-MDZ doses but was not associated with worse outcome. Discharge mortality was lower in the high-dose group (40% vs 62%, odds ratio 0.34, 95% confidence interval 0.13-0.92 in multivariate analysis).

CONCLUSIONS

High-dose cIV-MDZ treatment of refractory status epilepticus can be performed safely, is associated with a lower seizure rate after cIV-MDZ discontinuation, and may be associated with lower mortality than traditional lower-dose protocols.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that midazolam at higher infusion rates is associated with a reduction in seizure recurrence within 48 hours after discontinuation and may be associated with lower mortality.

First line management of prolonged convulsive seizures in children and adults: good practice points

Over the past decades, it has become clear that the most efficient way to prevent status epilepticus is to stop the seizure as fast as possible, and early treatment of prolonged convulsive seizures has become an integral part of the overall treatment strategy in epilepsy. Benzodiazepines are the first choice drugs to be used as emergency medication. This treatment in the early phases of a seizure often implies a 'pre-medical' setting before intervention of medically trained persons. In this paper, we propose "good practice points" for first line management of prolonged convulsive seizures in children and adults in a 'pre-medical' setting.

MicroRNAs in the pathophysiology and treatment of status epilepticus

MicroRNA (miRNA) are an important class of non-coding RNA which function as post-transcriptional regulators of gene expression in cells, repressing and fine-tuning protein output. Prolonged seizures (status epilepticus, SE) can cause damage to brain regions such as the hippocampus and result in cognitive deficits and the pathogenesis of epilepsy. Emerging work in animal models has found that SE produces select changes to miRNAs within the brain. Similar changes in over 20 miRNAs have been found in the hippocampus in two or more studies, suggesting conserved miRNA responses after SE. The miRNA changes that accompany SE are predicted to impact levels of multiple proteins involved in neuronal morphology and function, gliosis, neuroinflammation, and cell death. miRNA expression also displays select changes in the blood after SE, supporting blood genomic profiling as potential molecular biomarkers of seizure-damage or epileptogenesis. Intracerebral delivery of chemically modified antisense oligonucleotides (antagomirs) has been shown to have potent, specific and long-lasting effects on brain levels of miRNAs. Targeting miR-34a, miR-132 and miR-184 has been reported to alter seizure-induced neuronal death, whereas targeting miR-134 was neuroprotective, reduced seizure severity during status epilepticus and reduced the later emergence of recurrent spontaneous seizures. These studies support roles for miRNAs in the pathophysiology of status epilepticus and miRNAs may represent novel therapeutic targets to reduce brain injury and epileptogenesis.

Viral encephalitis in the ICU

Viral encephalitis causes an altered level of consciousness, which may be associated with fever, seizures, focal deficits, CSF pleocytosis, and abnormal neuroimaging. Potential pathogens include HSV, VZV, enterovirus, and in some regions, arboviruses. Autoimmune (eg, anti-NMDA receptor) and paraneoplastic encephalitis are responsible for some cases where no pathogen is identified. Indications for ICU admission include coma, status epilepticus and respiratory failure. Timely initiation of anti-viral therapy is crucial while relevant molecular and serological test results are being performed. Supportive care should be directed at the prevention and treatment of cerebral edema and other physiological derangements which may contribute to secondary neurological injury.

Gaps and opportunities in refractory status epilepticus research in children: a multi-center approach by the Pediatric Status Epilepticus Research Group (pSERG)

PURPOSE

Status epilepticus (SE) is a life-threatening condition that can be refractory to initial treatment. Randomized controlled studies to guide treatment choices, especially beyond first-line drugs, are not available. This report summarizes the evidence that guides the management of refractory convulsive SE (RCSE) in children, defines gaps in our clinical knowledge and describes the development and works of the 'pediatric Status Epilepticus Research Group' (pSERG).

METHODS

A literature review was performed to evaluate current gaps in the pediatric SE and RCSE literature. In person and online meetings helped to develop and expand the pSERG network.

RESULTS

The care of pediatric RCSE is largely based on extrapolations of limited evidence derived from adult literature and supplemented with case reports and case series in children. No comparative effectiveness trials have been performed in the pediatric population. Gaps in knowledge include risk factors for SE, biomarkers of SE and RCSE, second- and third-line treatment options, and long-term outcome.

CONCLUSION

The care of children with RCSE is based on limited evidence. In order to address these knowledge gaps, the multicenter pSERG was established to facilitate prospective collection, analysis, and sharing of de-identified data and biological specimens from children with RCSE. These data will allow identification of treatment strategies associated with better outcomes and delineate evidence-based interventions to improve the care of children with SE.

Issues related to symptomatic and disease-modifying treatments affecting cognitive and neuropsychiatric comorbidities of epilepsy

Many symptoms of neurologic or psychiatric illness--such as cognitive impairment, depression, anxiety, attention deficits, and migraine--occur more frequently in people with epilepsy than in the general population. These diverse comorbidities present an underappreciated problem for people with epilepsy and their caregivers because they decrease quality of life, complicate treatment, and increase mortality. In fact, it has been suggested that comorbidities can have a greater effect on quality of life in people with epilepsy than the seizures themselves. There is increasing recognition of the frequency and impact of cognitive and behavioral comorbidities of epilepsy, highlighted in the 2012 Institute of Medicine report on epilepsy. Comorbidities have also been acknowledged, as a National Institutes of Health (NIH) Benchmark area for research in epilepsy. However, relatively little progress has been made in developing new therapies directed specifically at comorbidities. On the other hand, there have been many advances in understanding underlying mechanisms. These advances have made it possible to identify novel targets for therapy and prevention. As part of the International League Against Epilepsy/American Epilepsy Society workshop on preclinical therapy development for epilepsy, our working group considered the current state of understanding related to terminology, models, and strategies for therapy development for the comorbidities of epilepsy. Herein we summarize our findings and suggest ways to accelerate development of new therapies. We also consider important issues to improve research including those related to methodology, nonpharmacologic therapies, biomarkers, and infrastructure.

[Non-convulsive status epilepticus: temporary fad or reality in need of treatment?]

The term non-convulsive status epilepticus (NCSE) refers to a heterogeneous group of diseases with different etiology, prognosis and treatment. The different forms of NCSE comprise about 25-50% of all status epilepticus cases. The most frequent form encountered in clinical practice is complex-partial SE but the rarer conditions of absence status, aura status and subtle SE are also included under this category. A diagnosis of NCSE should be considered in all patients with otherwise unexplained changes in consciousness or behavior and this diagnosis demands rapid further diagnostic work up including clinical examination, a detailed clinical history from the patient or an accompanying person, cranial computed tomography (CCT) and an electroencephalogram (EEG). If signs of an infectious or inflammatory disorder are present, a spinal tap is indicated. The EEG is of high relevance although interpretation can be challenging in NCSE.Absence status is usually treated by benzodiazepines and if necessary a broad spectrum anticonvulsive drug (ACD) such as valproic acid (VPA) can be added. The treatment of complex-partial SE follows the same scheme as that of generalized tonic-clonic SE and an initial benzodiazepine (i.v. lorazepam or intramuscular midazolam) followed by a bolus of one of the ACDs available as i.v. solution (e.g. VPA, phenytoin, phenobarbitol or levetiracetam). The third treatment step is general anesthesia if NCSE fails to be controlled. The aggressiveness of the applied therapy depends on the severity of the NCSE and the general condition of the patient. The prognosis is determined by the subtype of NCSE and the underlying etiology.

Safety and efficacy of intravenous lacosamide for adjunctive treatment of refractory status epilepticus: a comparative cohort study

BACKGROUND

Refractory status epilepticus (RSE) is an emergency with high mortality requiring neurointensive care. Treatment paradigms include first-generation antiepileptic drugs (AEDs) and anesthetics. Lacosamide (LCM) is a new AED, holding promise as a potent treatment option for RSE. High-level evidence regarding safety and efficacy in the treatment of RSE is lacking.

OBJECTIVE

The objective of the study was to evaluate the safety profile and efficacy of intravenous (i.v.) LCM as an add-on treatment in adult RSE patients.

METHODS

All consecutive RSE patients treated in the intensive care units (ICUs) of an academic tertiary care center between 2005 and 2011 were included. Severity of status epilepticus (SE) was graded by the SE Severity Scale (STESS), and SE etiology was categorized according to the guidelines of the International League Against Epilepsy (ILAE). Outcomes were seizure control, RSE duration, and death.

RESULTS

Of 111 RSE patients, 53 % were treated with LCM. Twenty-five patients with hypoxic-ischemic encephalopathy were excluded. Mortality was 30 %. Mean number of AEDs, duration, severity, and etiology of SE, as well as critical medical conditions did not differ between patients with and without LCM. While age tended to be higher, critical interventions, such as the use of anesthetics and mechanical ventilation, tended to be less frequent in patients with LCM. Seizure control tended to be achieved more frequently in patients with LCM (odds ratio, OR 2.34, 95 % CI 0.5-10.1, p = 0.252). Among patients with LCM, 51 % received LCM as the last AED (including hypoxic-ischemic encephalopathy), allowing the reasonable assumption that LCM was responsible for seizure control, which was achieved in 91 %. Multivariable analysis revealed a decreased mortality in patients with LCM (OR 0.34, 95 % CI 0.1-0.9, p = 0.035). A possible confounder in this context was the implementation of continuous video-electroencephalography (EEG) monitoring 6 months prior to the first use of i.v. LCM. There were no serious LCM-related adverse events.

CONCLUSION

LCM had a favorable safety profile as adjunctive treatment for RSE. Its use was associated with decreased mortality of RSE-a finding that might have been confounded by the implementation of continuous video-EEG monitoring in the ICU prior to the use of i.v. LCM, leading to heightened awareness as well as earlier diagnosis and treatment of SE. Randomized trials are warranted to further strengthen the evidence of efficacy of LCM for RSE treatment.

Therapeutic brain hypothermia, its mechanisms of action, and its prospects as a treatment for epilepsy

Cooling the core body temperature to 32-35°C, is almost standard practice for conditions such as cardiac arrest in adults, and perinatal hypoxic ischemic encephalopathy in neonates. Limited clinical data, and more extensive animal experiments, indicate that hypothermia could help control seizures, and could be applied directly to the brain using implantable devices. These data have fostered further research to evaluate whether cooling would be a viable means to treat refractory epilepsy. Although the effect of temperature on cellular physiology has long been recognized, with possibly dual effects on pyramidal cells and interneurons, the exact mechanisms underlying its beneficial effects, in particular in epilepsy, are yet to be discovered. This article reviews currently available clinical and laboratory data with a focus on cellular mechanisms of action and prospects of hypothermia as a treatment for intractable seizures.

Emergency neurological life support: status epilepticus

Patients with prolonged or rapidly recurring convulsions lasting more than 5 min are in status epilepticus (SE) and require immediate resuscitation. Although there are relatively few randomized clinical trials, available evidence and experience suggest that early and aggressive treatment of SE improves patient outcomes, for which reason it was chosen as an Emergency Neurologic Life Support protocol. The current approach to the emergency treatment of SE emphasizes rapid initiation of adequate doses of first line therapy, as well as accelerated second line anticonvulsant drugs and induced coma when these fail, coupled with admission to a unit capable of neurologic critical care and electroencephalography monitoring. This protocol not only will focus on the initial treatment of SE but also review subsequent steps in the protocol once the patient is hospitalized.

Glyoxalase 1 and its substrate methylglyoxal are novel regulators of seizure susceptibility

PURPOSE

Epilepsy is a complex disease characterized by a predisposition toward seizures. There are numerous barriers to the successful treatment of epilepsy. For instance, current antiepileptic drugs have adverse side effects and variable efficacies. Furthermore, the pathophysiologic basis of epilepsy remains largely elusive. Therefore, investigating novel genes and biologic processes underlying epilepsy may provide valuable insight and enable the development of new therapeutic agents. We previously identified methylglyoxal (MG) as an endogenous γ-aminobutyric acid (GABAA ) receptor agonist. Here, we investigated the role of MG and its catabolic enzyme, glyoxalase 1 (GLO1), in seizures.

METHODS

We pretreated mice with MG before seizure induction with picrotoxin or pilocarpine and then assessed seizures behaviorally or by electroencephalography (EEG). We then investigated the role of GLO1 in seizures by treating mice with a pharmacologic inhibitor of GLO1 before seizure induction with pilocarpine and measured subsequent seizure phenotypes. Next, we explored the genetic relationship between Glo1 expression and seizures. We analyzed seizure phenotypes among C57BL/6J × DBA/2J (BXD) recombinant inbred (RI) mice with differential Glo1 expression. Lastly, we investigated a causal role for Glo1 in seizures by administering pilocarpine to transgenic (Tg) mice that overexpress Glo1.

KEY FINDINGS

Pretreatment with MG attenuated pharmacologically-induced seizures at both the behavioral and EEG levels. GLO1 inhibition, which increases MG concentration in vivo, also attenuated seizures. Among BXD RI mice, high Glo1 expression was correlated with increased seizure susceptibility. Tg mice overexpressing Glo1 displayed reduced MG concentration in the brain and increased seizure severity.

SIGNIFICANCE

These data identify MG as an endogenous regulator of seizures. Similarly, inhibition of GLO1 attenuates seizures, suggesting that this may be a novel therapeutic approach for epilepsy. Furthermore, this system may represent an endogenous negative feedback loop whereby high metabolic activity increases inhibitory tone via local accumulation of MG. Finally, Glo1 may contribute to the genetic architecture of epilepsy, as Glo1 expression regulates both MG concentration and seizure severity.

Inhibition of the prostaglandin receptor EP2 following status epilepticus reduces delayed mortality and brain inflammation

Prostaglandin E2 is now widely recognized to play critical roles in brain inflammation and injury, although the responsible prostaglandin receptors have not been fully identified. We developed a potent and selective antagonist for the prostaglandin E2 receptor subtype EP2, TG6-10-1, with a sufficient pharmacokinetic profile to be used in vivo. We found that in the mouse pilocarpine model of status epilepticus (SE), systemic administration of TG6-10-1 completely recapitulates the effects of conditional ablation of cyclooxygenase-2 from principal forebrain neurons, namely reduced delayed mortality, accelerated recovery from weight loss, reduced brain inflammation, prevention of blood-brain barrier opening, and neuroprotection in the hippocampus, without modifying seizures acutely. Prolonged SE in humans causes high mortality and morbidity that are associated with brain inflammation and injury, but currently the only effective treatment is to stop the seizures quickly enough with anticonvulsants to prevent brain damage. Our results suggest that the prostaglandin receptor EP2 is critically involved in neuroinflammation and neurodegeneration, and point to EP2 receptor antagonism as an adjunctive therapeutic strategy to treat SE.

Robust photoregulation of GABA(A) receptors by allosteric modulation with a propofol analogue

Photochemical switches represent a powerful method for improving pharmacological therapies and controlling cellular physiology. Here we report the photo-regulation of GABA_A receptors (GABA_ARs) by a derivative of propofol (2,6-diisopropylphenol), a GABA_AR allosteric modulator, that we have modified to contain photo-isomerizable azobenzene. Using α₁β₂γ₂ GABA_ARs expressed in Xenopus laevis oocytes and native GABA_ARs of isolated retinal ganglion cells, we show that the trans-azobenzene isomer of the new compound (trans-MPC088), generated by visible light (wavelengths ~440 nm), potentiates the GABA-elicited response and at higher concentrations directly activates the receptors. cis-MPC088, generated from trans-MPC088 by UV light (~365 nm), produces little if any receptor potentiation/activation. In cerebellar slices, MPC088 co-applied with GABA affords bidirectional photo-modulation of Purkinje cell membrane current and spike-firing rate. The findings demonstrate photo-control of GABA_ARs by an allosteric ligand and open new avenues for fundamental and clinically oriented research on GABA_ARs, a major class of neurotransmitter receptors in the central nervous system.

An update on neurocritical care for the patient with kidney disease

Patients with kidney disease have increased rates of neurologic illness such as intracerebral hemorrhage and ischemic stroke. The acute care of patients with critical neurologic illness and concomitant kidney disease requires unique management considerations including attention to hyponatremia, renal replacement modalities in the setting of high intracranial pressure, reversal of coagulopathy, and seizure management to achieve good neurologic outcomes.

Guidelines for the evaluation and management of status epilepticus

Status epilepticus (SE) treatment strategies vary substantially from one institution to another due to the lack of data to support one treatment over another. To provide guidance for the acute treatment of SE in critically ill patients, the Neurocritical Care Society organized a writing committee to evaluate the literature and develop an evidence-based and expert consensus practice guideline. Literature searches were conducted using PubMed and studies meeting the criteria established by the writing committee were evaluated. Recommendations were developed based on the literature using standardized assessment methods from the American Heart Association and Grading of Recommendations Assessment, Development, and Evaluation systems, as well as expert opinion when sufficient data were lacking.

A comparative electrographic analysis of the effect of sec-butyl-propylacetamide on pharmacoresistant status epilepticus

Better treatment of status epilepticus (SE), which typically becomes refractory after about 30 min, will require new pharmacotherapies. The effect of sec-butyl-propylacetamide (SPD), an amide derivative of valproic acid (VPA), on electrographic status epilepticus (ESE) was compared quantitatively to other standard-of-care compounds. Cortical electroencephalograms (EEGs) were recorded from rats during ESE induced with lithium-pilocarpine. Using a previously-published algorithm, the effects of SPD on ESE were compared quantitatively to other relevant compounds. To confirm benzodiazepine resistance, diazepam (DZP) was shown to suppress ESE when administered 15 min after the first motor seizure, but not after 30 min (100mg/kg). VPA (300 mg/kg) also lacked efficacy at 30 min. SPD (130 mg/kg) strongly suppressed ESE at 30 min, less after 45 min, and not at 60 min. At a higher dose (180 mg/kg), SPD profoundly suppressed ESE at 60 min, similar to propofol (100mg/kg) and pentobarbital (30 mg/kg). After 4-6h of SPD-induced suppression, EEG activity often overshot control levels at 7-12h. Valnoctamide (VCD, 180 mg/kg), an SPD homolog, was also efficacious at 30 min. SPD blocks pilocarpine-induced electrographic seizures when administered at 1h after the first motor seizure. SPD has a faster onset and greater efficacy than DZP and VPA, and is similar to propofol and pentobarbital. SPD and structurally similar compounds may be useful for the treatment of refractory ESE. Further development and use of automated analyses of ESE may facilitate drug discovery for refractory SE.

Seizure treatment in transplant patients

OPINION STATEMENT

Solid organ transplantation is frequently complicated by a spectrum of seizure types, including single partial-onset or generalized tonic-clonic seizures, acute repetitive seizures or status epilepticus, and sometimes the evolution of symptomatic epilepsy. There is currently no specific evidence involving the transplant patient population to guide the selection, administration, or duration of antiepileptic drug (AED) therapy, so familiarity with clinical AED pharmacology and application of sound judgment are necessary for successful patient outcomes. An initial detailed search for symptomatic seizure etiologies, including metabolic, infectious, cerebrovascular, and calcineurin inhibitor treatment-related neurotoxic complications such as posterior reversible encephalopathy syndrome (PRES), is imperative, as underlying central nervous system disorders may impose additional serious risks to cerebral or general health if not promptly detected and appropriately treated. The mainstay for post-transplant seizure management is AED therapy directed toward the suspected seizure type. Unfavorable drug interactions could place the transplanted organ at risk, so choosing an AED with limited interaction potential is also crucial. When the transplanted organ is dysfunctional or vulnerable to rejection, AEDs without substantial hepatic metabolism are favored in post-liver transplant patients, whereas after renal transplantation, AEDs with predominantly renal elimination may require dosage adjustment to prevent adverse effects. Levetiracetam, gabapentin, pregabalin, and lacosamide are drugs of choice for treatment of partial-onset seizures in post-transplant patients given their efficacy spectrum, generally excellent tolerability, and lack of drug interaction potential. Levetiracetam is the drug of choice for primary generalized seizures in post-transplant patients. When intravenous drugs are necessary for acute seizure management, benzodiazepines and fosphenytoin are the traditional and best evidence-based options, although intravenous levetiracetam, valproate, and lacosamide are emerging options. Availability of several newer AEDs has greatly expanded the therapeutic armamentarium for safe and efficacious treatment of post-transplant seizures, but future prospective clinical trials and pharmacokinetic studies within this specific patient population are needed.

Sedation for critically ill or injured adults in the intensive care unit: a shifting paradigm

As most critically ill or injured patients will require some degree of sedation, the goal of this paper was to comprehensively review the literature associated with use of sedative agents in the intensive care unit (ICU). The first and selected latter portions of this article present a narrative overview of the shifting paradigm in ICU sedation practices, indications for uninterrupted or prolonged ICU sedation, and the pharmacology of sedative agents. In the second portion, we conducted a structured, although not entirely systematic, review of the available evidence associated with use of alternative sedative agents in critically ill or injured adults. Data sources for this review were derived by searching OVID MEDLINE and PubMed from their first available date until May 2012 for relevant randomized controlled trials (RCTs), systematic reviews and/or meta-analyses and economic evaluations. Advances in the technology of mechanical ventilation have permitted clinicians to limit the use of sedation among the critically ill through daily sedative interruptions or other means. These practices have been reported to result in improved mortality, a decreased length of ICU and hospital stay and a lower risk of drug-associated delirium. However, in some cases, prolonged or uninterrupted sedation may still be indicated, such as when patients develop intracranial hypertension following traumatic brain injury. The pharmacokinetics of sedative agents have clinical importance and may be altered by critical illness or injury, co-morbid conditions and/or drug-drug interactions. Although use of validated sedation scales to monitor depth of sedation is likely to reduce adverse events, they have no utility for patients receiving neuromuscular receptor blocking agents. Depth of sedation monitoring devices such as the Bispectral Index (BIS©) also have limitations. Among existing RCTs, no sedative agent has been reported to improve the risk of mortality among the critically ill or injured. Moreover, although propofol may be associated with a shorter time to tracheal extubation and recovery from sedation than midazolam, the risk of hypertriglyceridaemia and hypotension is higher with propofol. Despite dexmedetomidine being linked with a lower risk of drug-associated delirium than alternative sedative agents, this drug increases risk of bradycardia and hypotension. Among adults with severe traumatic brain injury, there are insufficient data to suggest that any single sedative agent decreases the risk of subsequent poor neurological outcomes or mortality. The lack of examination of confounders, including the type of healthcare system in which the investigation was conducted, is a major limitation of existing pharmacoeconomic analyses, which likely limits generalizability of their results.

Topiramate as an adjunctive treatment in patients with refractory status epilepticus: an observational cohort study

BACKGROUND

Refractory status epilepticus (RSE) is the most severe manifestation of status epilepticus (SE), often requiring intensive care and therapeutic coma. It is associated with prolonged intensive care unit (ICU) and hospital stays, as well as increased morbidity and mortality. Treatment involves both intravenous anaesthetics and antiepileptic drugs (AEDs) that can be administrated intravenously, by nasogastric tube or by percutaneous endoscopic gastrostomy. Experience with some of the newer AEDs for the treatment of RSE is restricted and higher-class evidence regarding tolerability and efficacy is lacking. Topiramate is a potent broad-spectrum AED with several modes of action, including blockade of the ionotropic glutamatergic AMPA receptor, which is likely to be an important mechanism for the treatment of SE. While there is no commercially available intravenous formulation, topiramate can be administered enterally, which may make it suitable for the treatment of RSE.

OBJECTIVE

The objective of this study was to evaluate the tolerability, safety profile and efficacy of adjunctive and enterally administered topiramate in patients with RSE.

METHODS

A medical chart review was performed of all consecutive patients treated for RSE between August 2004 and December 2011 at the ICU of the University Hospital Basel (Basel, Switzerland).

RESULTS

113 (43%) of all consecutive 268 patients with SE developed RSE. Of those, 35 (31%) were treated with topiramate. Median age was 60.5 years. Topiramate was used as an add-on treatment after 1-6 (median 4) prior administered AEDs had failed. It was introduced after a median of 2 (range 2-23) days for a duration of 1-24 (median 3) days. The response rate after topiramate administration as the third AED was 86% (6/7 patients), and remained stable at 67% after administration as the fourth, fifth, sixth or seventh AED when the groups of successfully and probably successfully treated patients were pooled. Overall, RSE was terminated in 71% of patients within 72 hours after first administration of topiramate, in 9% of patients, within 24 hours (none in the 800 mg/day group; 9% in the 400-799 mg/day group; and 11% in the <400 mg/day group). Mortality was 31% and was not strictly dependent on failure to terminate RSE, but also on the underlying aetiology of RSE. There were no serious or fatal adverse events directly attributable to topiramate. Adverse effects included slight hyperchloremic acidosis and hyperammonemia (all associated with co-medication with valproic acid).

CONCLUSION

Treatment with enterally administered topiramate was feasible, well tolerated and had a good safety profile in patients with RSE in this observational, single-centre, cohort study. Refractory SE was terminated in the majority of patients within 3 days after initiation of topiramate. Prospective studies are warranted to further evaluate topiramate for the treatment of RSE.

Early ketamine to treat refractory status epilepticus

BACKGROUND

Management of refractory status epilepticus (SE) involves administration of intravenous γ-aminobutyric acid (GABA(A)) receptor agonists, such as benzodiazepines, barbiturates, or propofol. Animal models suggest that reductions in synaptic GABA(A) receptors may cause these drugs to become less effective as the duration of SE increases. This may explain the large doses that are commonly required to control seizures, which in turn contributes to a high incidence of complications, including hypotension and the need for vasopressors. In contrast, expression of excitatory N-methyl-D-aspartate (NMDA) receptors increases with prolonged SE and their stimulation by glutamate may propagate seizure activity. Ketamine is a NMDA-receptor antagonist that is considered promising as treatment for refractory SE. Compared with other anaesthetic drugs, ketamine produces less hypotension.

METHODS

This report describes a patient who developed worsening hypotension with escalating doses of midazolam and propofol in the context of non-convulsive SE. He was therefore treated with ketamine within hours of being diagnosed.

RESULTS

Ketamine was immediately efficacious at reducing the frequency, amplitude, and duration of seizures. The dose was rapidly titrated upwards using quantitative continuous EEG monitoring, until seizures were completely abolished. SE did not recur with weaning of sedatives and he went on to have an excellent recovery. A small number of previous reports have found ketamine to abort late SE. In most cases, ketamine was administered several days into the course, and outcomes were poor even though seizures were controlled.

CONCLUSION

Larger series and phase I clinical trial(s) of ketamine for treatment of refractory SE seem warranted.

Refractory status epilepticus

PURPOSE OF REVIEW

Refractory status epilepticus (RSE) has a high morbidity and mortality. There are currently no definitive data to guide both the optimal choice of therapy and treatment goals. This review focuses on RSE diagnosis and outcome and discusses both commonly used and anecdotal therapies for RSE.

RECENT FINDINGS

The challenges in performing randomized controlled trials (RCTs) in neurocritical care and more specifically for the treatment of RSE are illustrated by the early termination of the first RCT of RSE due to low recruitment that compared propofol to barbiturates. Recent case series include the successful treatment of recurrent RSE with ketamine, intravenous lacosamide as an add-on treatment, the use of combination antiepileptics (phenytoin, levetiracetam, and pregabalin), and surgical treatments (vagal nerve and deep brain stimulation) for the control of RSE.

SUMMARY

A number of different therapeutic options are available for the treatment of RSE but none have been shown to be superior to others at this point.

Newer antiepileptic drugs in the treatment of status epilepticus: impact on prognosis

Newer antiepileptic drugs (AEDs) are increasingly prescribed and seem to have a comparable efficacy as the classical AEDs; however, their impact on status epilepticus (SE) prognosis has received little attention. In our prospective SE database (2006-2010), we assessed the use of older versus newer AEDs (levetiracetam, pregabalin, topiramate, lacosamide) over time and its relationship to outcome (return to clinical baseline conditions, new handicap, or death). Newer AEDs were used more often toward the end of the study period (42% of episodes versus 30%). After adjustment for SE etiology, SE severity score, and number of compounds needed to terminate SE, newer AEDs were independently related to a reduced likelihood of return to baseline (p<0.001) but not to increased mortality. These findings seem in line with recent findings on refractory epilepsy. Also, in view of the higher price of the newer AEDs, well-designed, prospective assessments analyzing the impact of newer AEDs on efficacy and tolerability in patients with SE appear mandatory.