A comparison of four treatments for generalized convulsive status epilepticus. Veterans Affairs Status Epilepticus Cooperative Study Group

Progress in clinical neurosciences: Status epilepticus: a critical review of management options

Although generalized tonic-clonic status epilepticus (SE) is frequently seen, an evidence-based approach to management is limited by a lack of randomized clinical studies. Clinical practice, therefore, relies on a combination of expert recommendations, local hospital guidelines and dogma based on individual preference and past successes. This review explores selected and controversial aspects of SE in adults and provides a critical appraisal of currently recommended management strategies.

Is it status?

Nonconvulsive status epilepticus (NCSE) is difficult to diagnose in the obtunded/comatose patient. Such patients often have other serious medical conditions, and the diagnosis is frequently delayed. We review criteria for diagnosis, treatment, and prognosis of NCSE in this setting. Terms that have been used to describe SE in obtunded/comatose patients without tonic-clonic convulsions include subtle generalized SE, electrographic SE, SE in comatose patients, generalized electrographic SE, non-tonic-clonic SE, subclinical SE, and NCSE. Sometimes the same term has been used when describing different disorders, and different terms are often applied for the same entity. The incidence of NCSE in obtunded/comatose patients is uncertain. Clinically they may display subtle, intermittent focal or multifocal rhythmic movements suggestive of seizures; there may not be movements. NCSE can occur in a variety of disorders, including hypoxia, metabolic disturbances, and after convulsive seizures. A number of EEG patterns have been described in NCSE, and many of these are controversial, particularly as to whether they are ictal. These include periodic lateralized epileptiform discharges (PLEDS), bilateral independent PLEDS (BIPLEDS), periodic epileptiform discharges (PEDS), which can be either focal or generalized, and generalized triphasic waves (TWs). The diagnostic criteria for NCSE also are controversial, and there are no agreed-on criteria to diagnose NCSE in obtunded/comatose patients, nor is there consensus on how it should it be treated. Furthermore, outcome is poor, and several studies suggest that treatment may not be helpful.

Continuous EEG monitoring in the intensive care unit

Continuous EEG (CEEG) monitoring allows uninterrupted assessment of cerebral cortical activity with good spatial resolution and excellent temporal resolution. Thus, this procedure provides a means of constantly assessing brain function in critically ill obtunded and comatose patients. Recent advances in digital EEG acquisition, storage, quantitative analysis, and transmission have made CEEG monitoring in the intensive care unit (ICU) technically feasible and useful. This article summarizes the indications and methodology of CEEG monitoring in the ICU, and discusses the role of some quantitative EEG analysis techniques in near real-time remote observation of CEEG recordings. Clinical examples of CEEG use, including monitoring of status epilepticus, assessment of ongoing therapy for treatment of seizures in critically ill patients, and monitoring for cerebral ischemia, are presented. Areas requiring further development of CEEG monitoring techniques and indications are discussed.

The current state of treatment of status epilepticus

There have been many important developments in the diagnosis and treatment of status epilepticus in the recent past. Earlier treatment, including at home by caregivers and in the field by paramedics, has been shown to be safe and effective. Rapid-acting anesthetic agents, such as midazolam and propofol, are being used more often for refractory status epilepticus, though clinical trials are lacking. Nonconvulsive status epilepticus is being considered and recognized more often, including in ambulatory patients with a confusional state, after convulsive status epilepticus, and in critically ill patients. Modern technology and continuous digital electroencephalogram (EEG) recordings have taught us many things, but have raised at least as many questions. Much work needs to be done regarding the significance of certain EEG patterns (particularly periodic discharges) and when and how to treat them. This article reviews these issues, concentrating on recent advances and practical issues related to the clinical care of patients with status epilepticus.

Prehospital Treatment of Status Epilepticus with Benzodiazepines Is Effective and Safe

Benzodiazepines are an effective and safe treatment of status epilepticus and serial seizures when used in an out-of-hospital setting. Intravenously administered lorazepam is somewhat superior to diazepam for the treatment of status epilepticus. Treatment of status epilepticus should be initiated when seizures have lasted 5-7 minutes.

Status Epilepticus

Status epilepticus (SE) is a common neurologic emergency with a high mortality. Immediate recognition and rapid treatment are essential. After initial stabilization of airway and circulation, the patient should be treated as soon as possible with an intravenous (IV) benzodiazepine, followed immediately by IV fosphenytoin. If SE persists, general anesthesia should be initiated, with intubation and cardiac monitoring. Electroencephalogram must also be monitored to ensure suppression of all seizures. Etiology of SE should be assessed through history, examination, blood tests, and brain imaging.

Prehospital Treatment of Status Epilepticus with Benzodiazepines is Effective and Safe

Benzodiazepines are an effective and safe treatment of status epilepticus and serial seizures when used in an out-of-hospital setting. Intravenously administered lorazepam is somewhat superior to diazepam for the treatment of status epilepticus. Treatment of status epilepticus should be initiated when seizures have lasted 5–7 minutes.

Comparative audit of intravenous lorazepam and diazepam in the emergency treatment of convulsive status epilepticus in children

There is little evidence on which to judge the optimal treatment for convulsive status epilepticus (CSE) in children. This study compares the effect of intravenous (iv) lorazepam with iv diazepam as the first line of treatment of CSE. We studied all children with prolonged seizures arriving in the Accident and Emergency (A&E) Department in two separate periods. In the first 6-month period iv diazepam was used as standard treatment, in the second 1-year period iv lorazepam was used. We measured latency to stopping of seizure and any adverse events. A successful treatment was defined as one in which the seizure clinically ceased within 15 minutes after siting the iv cannula, requiring no further treatment.Intravenous diazepam (0.32 mg kg (-1)) was used in 17 of 26 patients, whilst iv lorazepam (0.13 mg kg (-1)) was used in 31 of 59. There were no differences between the two groups regarding age, sex and seizure type.The seizure was successfully controlled 15 minutes after siting the iv cannula in 11 (65%) patients treated with diazepam (median time of 3 minutes) and in 20 (65%) patients treated with lorazepam (median time of 5 minutes). These preliminary results suggest that iv lorazepam may be as effective as iv diazepam.

Strategies for optimizing antiepileptic drug therapy in elderly people

The elderly take more antiepileptic drugs (AEDs) than all other adults. This extensive use directly correlates with an increased prevalence of epilepsy in a growing population of older people, as well as other neuropsychiatric conditions such as neuropathic pain and behavioral disorders associated with dementia and for which AEDs are administered. The agents account for nearly 10% of all adverse drug reactions in the elderly and are the fourth leading cause of adverse drug reactions in nursing home residents. Numerous factors associated with advanced age contribute to the high frequency of untoward drug effects in this population; however, strategies are available to ensure optimal outcomes.

Phenobarbital and MK-801, but not phenytoin, improve the long-term outcome of status epilepticus

To examine the effect of therapy on status epilepticus (SE) acutely and on long-term outcome, we compared three drugs with three different mechanisms. Phenobarbital, MK-801, and phenytoin were administered at 1, 2, and 4 hours after initiation of limbic status epilepticus by "continuous" hippocampal stimulation in rats. We evaluated the effects of these drugs on the course of SE and the subsequent development of chronic epilepsy. Phenobarbital and MK-801 were superior to phenytoin in suppressing SE and in preventing chronic epilepsy. There was no benefit if treatment was given 2 hours after the initiation of SE. Phenobarbital was most effective in suppressing electrographic seizure activity, but MK-801 had a slightly wider window for the prevention of chronic epilepsy. Early treatment, rather than electrographic suppression of SE, correlated with prevention of chronic epilepsy. This study shows that the drugs administered, which have different mechanisms of action, have clear differences in altering the outcomes. The findings suggest that studies of SE treatment should examine the effect of therapy on SE itself, as well as the long-term benefits of each treatment. The use of N-methyl-D-aspartate receptor antagonists should be considered early in the treatment of SE.

Treatment of refractory status epilepticus with pentobarbital, propofol, or midazolam: a systematic review

BACKGROUND

New continuous infusion antiepileptic drugs (cIV-AEDs) offer alternatives to pentobarbital for the treatment of refractory status epilepticus (RSE). However, no prospective randomized studies have evaluated the treatment of RSE. This systematic review compares the efficacy of midazolam (MDL), propofol (PRO), and pentobarbital (PTB) for terminating seizures and improving outcome in RSE patients.

METHODS

We performed a literature search of studies describing the use of MDL, PRO, or PTB for the treatment of RSE published between January 1970 and September 2001, by using MEDLINE, OVID, and manually searched bibliographies. We included peer-reviewed studies of adult patients with SE refractory to at least two standard AEDs. Main outcome measures were the frequency of immediate treatment failure (clinical or electrographic seizures occurring 1 to 6 h after starting cIV-AED therapy) and mortality according to choice of agent and titration goal (cIV-AED titration to "seizure suppression" versus "EEG background suppression").

RESULTS

Twenty-eight studies describing a total of 193 patients fulfilled our selection criteria: MDL (n = 54), PRO (n = 33), and PTB (n = 106). Forty-eight percent of patients died, and mortality was not significantly associated with the choice of agent or titration goal. PTB was usually titrated to EEG background suppression by using intermittent EEG monitoring, whereas MDL and PRO were more often titrated to seizure suppression with continuous EEG monitoring. Compared with treatment with MDL or PRO, PTB treatment was associated with a lower frequency of short-term treatment failure (8 vs. 23%; p < 0.01), breakthrough seizures (12 vs. 42%; p < 0.001), and changes to a different cIV-AED (3 vs. 21%; p < 0.001), and a higher frequency of hypotension (systolic blood pressure <100 mm Hg; 77 vs. 34%; p < 0.001). Compared with seizure suppression (n = 59), titration of treatment to EEG background suppression (n = 87) was associated with a lower frequency of breakthrough seizures (4 vs. 53%; p < 0.001) and a higher frequency of hypotension (76 vs. 29%; p < 0.001).

CONCLUSIONS

Despite the inherent limitations of a systematic review, our results suggest that treatment with PTB, or any cIV-AED infusion to attain EEG background suppression, may be more effective than other strategies for treating RSE. However, these interventions also were associated with an increased frequency of hypotension, and no effect on mortality was seen. A prospective randomized trial comparing different agents and titration goals for RSE with obligatory continuous EEG monitoring is needed.

Treating epilepsy in the elderly: safety considerations

The incidence of epilepsy increases with advancing age. Epilepsy in the elderly has different aetiologies from that in younger populations, cerebrovascular disease being the most common condition associated with seizures. Partial seizures are the predominant seizure type in older patients. A diagnosis of epilepsy in the elderly is based mainly on the history and is frequently delayed. In addition, seizure imitators are especially frequent. In many cases ancillary tests for diagnosis may show normal age-related variants, sometimes making results difficult to interpret. Treating epilepsy in the elderly is problematic due to a number of issues that relate to age and comorbidity. The physical changes associated with increasing age frequently lead to changes in the pharmacokinetics of many anticonvulsants. The treatment of epilepsy in the elderly is also complicated by the existence of other diseases that might affect the metabolism or excretion of anticonvulsants and the presence of concomitant medications that might interact with them. Moreover, specific trials of anticonvulsants in the aged population are scarce. General guidelines for treatment include starting at lower doses, slowing the titration schedule, individualising the choice of anticonvulsant to the characteristics of the patient, avoiding anticonvulsants with important cognitive or sedative adverse effects, and where possible, treating with monotherapy.

Status epilepticus and acute serial seizures in children

Status epilepticus is defined as a seizure that persists for a sufficient length of time or is repeated frequently enough to produce a fixed and enduring epileptic condition of 30 minutes or longer. Status epilepticus is a life-threatening condition that often occurs in children. The degree of mortality and neurologic morbidity, as well as the risk for recurrence, is highly dependent on the etiology and duration of the seizures. Although much has been written about pediatric status epilepticus, many issues remain unresolved. A better understanding of the different types of seizures and their etiologies may help in the prevention and treatment of status epilepticus. The vast extent of status epilepticus in both children and adults mandates that new options for prevention and treatment be given a close scrutiny and high priority. This article will review the most current information on convulsive and nonconvulsive status epilepticus, including the potential for neurologic damage, changes in magnetic resonance imaging after status epilepticus, risk for recurrence, and current treatment options available for treating status epilepticus in children.

Clinical review: status epilepticus

Status epilepticus (SE) has an annual incidence exceeding 100,000 cases in the United States alone, of which more than 20% result in death. Thus, increased awareness of presentation, etiologies, and treatment of SE is essential in the practice of critical care medicine. This review discusses current definitions of SE, as well as its clinical presentation and classification. The recent literature on epidemiology is reviewed, including morbidity and mortality data. An overview of the systemic pathophysiologic effects of SE is presented. Finally, significant studies on the treatment of acute SE and refractory SE are reviewed, including the use of anticonvulsants, such as benzodiazepines, and other drugs.

Status epilepticus in older patients: epidemiology and treatment options

Status epilepticus (SE) is a medical and neurological emergency that has been associated with significant morbidity and mortality. The most widely accepted definition of SE is more than 30 minutes of either continuous seizure activity, or intermittent seizures without full recovery of consciousness between seizures. SE is a major clinical concern in the elderly population, both because it has increased incidence in the elderly compared with the general population, and because of concurrent medical conditions that are more likely to complicate therapy and worsen prognosis in elderly individuals. The incidence of SE in the elderly is almost twice that of the general population at 86 per 100,000 per year. With the anticipated growth of the elderly population, SE is likely to become an increasingly common problem facing clinicians, and an important public health issue. The elderly have the highest SE-associated mortality of any age group at 38%, and the very old elderly (>80 years of age) have a mortality of at least 50%. Acute or remote stroke is the most common aetiology of SE in the elderly. Nonconvulsive SE (NCSE) has a wide range of clinical presentations, ranging from confusion to obtundation. It occurs commonly in elderly patients who are critically ill and in the setting of coma. Electroencephalogram is the only reliable method of diagnosing NCSE. The goal of treatment for SE is rapid cessation of clinical and electrical seizure activity. Most treatment protocols call for the immediate administration of an intravenous benzodiazepine, followed by phenytoin or fosphenytoin. Recent studies suggest that when this initial treatment of SE fails, little is gained by using additional standard drugs. General anaesthetic agents (such as pentobarbital, midazolam, or propofol) should be expeditiously employed, although these treatments have their own potential complications. Intravenous valproic acid is a recent addition to the armamentarium of drugs for the treatment of SE, with a low risk of hypotension, respiratory depression and hypotension, making it a potentially useful drug for the treatment of SE in the elderly. However, further information is needed to establish its role in the overall treatment of SE.

A comparison of lorazepam, diazepam, and placebo for the treatment of out-of-hospital status epilepticus

BACKGROUND

It is uncertain whether the administration of benzodiazepines by paramedics is an effective and safe treatment for out-of-hospital status epilepticus.

METHODS

We conducted a randomized, double-blind trial to evaluate intravenous benzodiazepines administered by paramedics for the treatment of out-of-hospital status epilepticus. Adults with prolonged (lasting five minutes or more) or repetitive generalized convulsive seizures received intravenous diazepam (5 mg), lorazepam (2 mg), or placebo. An identical second injection was given if needed.

RESULTS

Of the 205 patients enrolled, 66 received lorazepam, 68 received diazepam, and 71 received placebo. Status epilepticus had been terminated on arrival at the emergency department in more patients treated with lorazepam (59.1 percent) or diazepam (42.6 percent) than patients given placebo (21.1 percent) (P=0.001). After adjustment for covariates, the odds ratio for termination of status epilepticus by the time of arrival in the lorazepam group as compared with the placebo group was 4.8 (95 percent confidence interval, 1.9 to 13.0). The odds ratio was 1.9 (95 percent confidence interval, 0.8 to 4.4) in the lorazepam group as compared with the diazepam group and 2.3 (95 percent confidence interval, 1.0 to 5.9) in the diazepam group as compared with the placebo group. The rates of respiratory or circulatory complications (indicated by bag valve-mask ventilation or an attempt at intubation, hypotension, or cardiac dysrhythmia) after the study treatment was administered were 10.6 percent for the lorazepam group, 10.3 percent for the diazepam group, and 22.5 percent for the placebo group (P=0.08).

CONCLUSIONS

Benzodiazepines are safe and effective when administered by paramedics for out-of-hospital status epilepticus in adults. Lorazepam is likely to be a better therapy than diazepam.

The etiology and diagnosis of status epilepticus

Status epilepticus (SE) is a common, serious, potentially life-threatening, neurologic emergency characterized by prolonged seizure activity. Generalized convulsive status epilepticus (GCSE) is the most widely recognized form of SE. Direct consequences of convulsive movements from SE can result in injury to the body and brain. Nonconvulsive status epilepticus (NCSE) is underrecognized, with controversy surrounding the consequences and treatment. High mortality rates with GCSE have been noted in the past. New treatments for SE are emerging with new parenteral drug formulations as well as new agents for refractory SE, offering an opportunity to improve outcome. Special drug delivery systems, drug combinations, and neuroprotective agents that prevent the subsequent development of epilepsy may soon emerge as future options for treating SE.

Status epilepticus

Status epilepticus is a medical emergency that requires rapid and vigorous treatment to prevent neuronal damage and systemic complications. Failure to diagnose and treat status epilepticus accurately and effectively results in significant morbidity and mortality. Cerebral metabolic decompensation occurs after approximately 30 min of uncontrolled convulsive activity, and the window for treatment is therefore limited. Therapy should proceed simultaneously on four fronts: termination of seizures; prevention of seizure recurrence once status is controlled; management of precipitating causes of status epilepticus; management of the complications. This article reviews current opinions about the classification, aetiology and pathophysiology of adult generalised convulsive status epilepticus and details practical management strategies for treatment of this life-threatening condition.

The prehospital treatment of status epilepticus (PHTSE) study: design and methodology

Status epilepticus is a neurological emergency that is typically first encountered and managed in the prehospital environment. Although aggressive pharmacological treatment of status epilepticus is well established in the emergency department and hospital settings, the relative risks and benefits of active therapy for status epilepticus in the prehospital setting are not known. The Prehospital Treatment of Status Epilepticus (PHTSE) study is a prospective, randomized, double-blind, placebo-controlled study designed to address the following aims: (1) to determine whether administration of benzodiazepines by paramedics is an effective and safe means of treating status epilepticus in the prehospital setting and whether this therapy influences longer-term patient outcome, (2) to determine whether lorazepam is superior to diazepam for the treatment of status epilepticus in the prehospital setting, and (3) to determine whether control of status epilepticus prior to arrival to the emergency department influences patient disposition. The initial phase of the PHTSE study began in January 1994 and was completed in February 1999 after the successful enrollment of 205 patients into the three treatment arms. In this paper, we describe the rationale for the conceptualization of the study and details of the study design and methodology, and emphasize some aspects of study implementation that are unique to research involving the emergency medical system.

Emergency department management of patients with seizures: a multicenter study

OBJECTIVES

Patients with seizure disorders are common in the emergency department (ED), yet little is known regarding the management of these patients. This study was performed to define the frequency of patients with seizure disorders in the ED patient population and to determine possible seizure etiologies, characteristics of diagnostic activities, treatments, and dispositions.

METHODS

Twelve EDs monitored all patients with a chief complaint related to seizure disorders presenting over 18.25 days (5% of the calendar year) in late 1997. Retrospective chart review was used to gather specific data regarding these consecutive cases.

RESULTS

Of the 31,508 patients who presented to these 12 EDs during the study period, 368 (1.2%) had complaints related to seizures. Three hundred sixty-two charts were available for analysis and make up the study population. Two hundred fifty-seven (71%) utilized emergency medical services (EMS) for transport and care. Advanced care, including intravenous access, laboratory work, cardiac monitoring, or oxygen administration, was utilized in 304 (84%) patients. Antiepileptic drugs were given in 199 (55%) patients. Ethanol withdrawal or low antiepileptic drug levels were implicated as contributing factors in 177 (49%) of patients. New-onset seizures were thought to be present in 94 (26%) patients. Status epilepticus occurred in only 21 (6%) patients. Ninety-eight (27%) of all patients were admitted to the hospital.

CONCLUSIONS

Patients with presenting complaints related to seizures are frequent in the ED population and make considerable demands on EMS and ED resources. Six percent of patients with seizure-related presentations were in status epilepticus and more than a fourth of all patients required hospitalization.

Status epilepticus

Status epilepticus is a serious medical emergency that requires prompt and appropriate intervention. Maintenance of adequate vital function with attention to airway, breathing, and circulation; prevention of systemic complications; and rapid termination of seizures must be coupled with investigating and treating any underlying cause. In most patients with SE, the use of adequate dosages of first-line antiepileptic agents allows for the successful and rapid termination of SE and avoidance of potential neurologic complications. Refractory SE requires more aggressive treatment, often the use of intravenous anesthetic agents and intense monitoring, and therefore must be managed in a pediatric intensive care unit with a multidisciplinary approach. Large, controlled, multicenter, comparative studies are needed urgently to clarify better the optimal management of these patients.

Treatment of status epilepticus

The approach to treatment of status epilepticus has changed because of the demonstration of decreased mortality with rapid intervention, completion of a randomized, double-blind VA Cooperative study comparing first-line agents, and further understanding of the pathophysiologic changes discovered in experimental animal studies. This article reviews the treatments of generalized convulsive status epilepticus in the prehospital, emergency department, and intensive care unit settings.

Electrophysiologic monitoring in neurointensive care

Cumulative evidence of potential benefits of electroencephalography (EEG) and evoked potentials in the management of patients with acute cerebral damage has been confirmed. Continuous EEG monitoring is the best method for detecting nonconvulsive seizures and is strongly recommended for the treatment of status epilepticus. Continuously displayed, validated quantitative EEG may facilitate early detection of secondary cerebral insults and may play a decision-making role in the management of patients with head injury, stroke, or subarachnoid hemorrhage. Long-latency auditory evoked potentials and cognitive components constitute a new field of interest for the progress of comatose patients. Motor evoked potentials may become clinically important both in acutely injured and elective postoperative patients. In the neurointensive care units adequate techniques can be selected to answer targeted clinical questions. The efficacy can be improved by implementing educational projects based on ad hoc training of nurses and neurointensive care specialists.

The mechanisms of action of commonly used antiepileptic drugs

In the past decade, nine new drugs have been licensed for the treatment of epilepsy. With limited clinical experience of these agents, the mechanisms of action of antiepileptic drugs may be an important criterion in the selection of the most suitable treatment regimens for individual patients. At the cellular level, three basic mechanisms are recognised: modulation of voltage-dependent ion channels, enhancement of inhibitory neurotransmission, and attenuation of excitatory transmission. In this review, we will attempt to introduce the concepts of ion channel and neurotransmitter modulation and, thereafter, group currently used antiepileptic drugs according to their principal mechanisms of action.

Therapy of status epilepticus in adults and children

Clinical studies of the treatment of status epilepticus are extremely difficult to carry out, therefore a paucity of new clinical studies have been reported. Much of the progress regarding the therapy of status epilepticus has come from a better understanding of the epidemiology of status epilepticus and its consequences and from laboratory studies of experimental status. Status epilepticus has been used as an experimental tool to study epileptogenesis, but from such studies have come insights that can be applied to the therapy of status epilepticus itself. This review will focus on information from epidemiological, experimental, and clinical studies of status epilepticus, which may contribute to the improved treatment of this life-threatening disorder.

Seizures in the adult intensive care unit

Seizures are a common occurrence in the intensive care unit (ICU). The presentation of seizures is usually as focal or generalized motor convulsions, but other seizure types may occur. Etiologies of the seizures are typically secondary either to primary neurologic pathology or a consequence of critical illness and clinical management. Particularly important as precipitants of seizures are hypoxia/ischemia, drug toxicity, and metabolic abnormalities. It is important to properly diagnose the seizure type and its cause to ensure appropriate therapy. Most seizures occur singly, and recurrence is usually prevented with initiation of anticonvulsant therapy. However, status epilepticus may develop, which requires emergent treatment before irreversible brain injury occurs. Treatment with anticonvulsants is not without untoward risks, however, and primary toxicities of these agents is reviewed. After traumatic head injury, brain surgery, or cerebrovascular accidents, many patients are at risk for seizures. Current data on the benefits of prophylactic therapy for such patients is also reviewed.

Current practice in administration and clinical criteria of emergent EEG

Policies of administration and availability of EEG offered during nonbusiness hours vary widely among EEG laboratories. The authors surveyed medical directors of accredited EEG laboratories (n = 84) to determine the ranges of availability and clinical indications for approval of continuously available emergent EEG (E-EEG). Of 46 respondents, 37 (80%) offered E-EEG. Two centers recently lost funding for E-EEG. Availability was not associated with the total number of EEGs performed annually. The mean estimated response time from request to expert interpretation was 3 +/- 4 hours (range, 1-24 hours). The five clinical indications for which most respondents approved E-EEGs were possible nonconvulsive status epilepticus (100%), treatment of status epilepticus (84%), cerebral death exam (81%), diagnosis of convulsive status epilepticus (79%), and diagnosis of coma or encephalopathy (70%). Respondents disagreed widely when asked which clinical situations merited E-EEG, with some approving all requests and others denying all except for nonconvulsive status epilepticus. The wide range of current practice suggests that research focused on outcomes of aggressive, EEG-aided patient evaluation and treatment are needed to define better the costs and benefits of a continuously available EEG service.

Status epilepticus arising de novo in hospitalized patients: an analysis of 41 patients

Most of the information on predisposing factors and mortality in status epilepticus (SE) arises from data obtained from patients presenting to the casualty department. However, another population which is frequently seen by consultative neurologists are medically ill patients who develop SE while in hospital. These patients are often notoriously difficult to treat once SE arises. We sought to characterize patients at risk for SE arising when they are hospitalized for other reasons. By doing this, risk factors for developing SE and prognostic indicators might be determined. We retrospectively reviewed records from three urban hospitals in the United States to identify hospitalized patients developing SE over a 1 year period. SE was defined as a clinical seizure lasting 30 minutes or longer, or repeated seizures without recovery. Patients who were admitted in SE or for an epilepsy-related problem, or who were less than 1 year old were excluded from the study. Forty-one patients with in-hospital SE were identified. There were 28 males and 13 females with an age range from 1 to 91 years (mean: 60 years, median: 65 years). The mean interval from hospital admission to the onset of status epilepticus was 26 days. Nineteen (46%) patients had a prior history of either epilepsy or symptomatic seizures, and of these, 10 were inadequately treated as judged by serum anticonvulsant levels at the time SE developed. Focal brain abnormality was present in 26 (63%) patients, the most common of which was stroke (17 patients ). Major metabolic derangements including hypoxia, electrolyte imbalance, hepatic encephalopathy, and sepsis were present in 23 (56%) patients. Eleven (27%) patients were being treated with theophylline preparations at the time SE developed. Mortality in this group of patients with in-hospital SE was 61% (25 deaths), with about one-third dying while in status, and two-thirds dying subsequently in hospital. In this retrospective study, there was no clear relationship between mortality and the duration of SE in this group of patients. In-hospital development of SE is usually related to underlying focal brain abnormality, especially stroke, in combination with systemic metabolic derangement. Prognosis is poor, and appears to be more related to underlying conditions rather than to status duration. More accurate prospective studies are warranted.

[Status epilepticus: pharmacokinetic basis of anticonvulsant treatment in adults]

In status epilepticus, the optimal efficacy of the antiepileptic drugs depends notably on effective, quickly reached and sufficiently lasting cerebral concentrations and the optimal tolerability notably on the lack of excessive storage in the brain and other tissues. So, the best efficacy-tolerability ratio of these drugs is largely determined by their pharmacokinetic properties. A linear kinetics, a not too short distribution half-life, a neither too brief nor too long elimination half-life, a fast and easy crossing of the blood-brain barrier and the lack of long-lasting accumulation in fat tissues are among the main ideal pharmacokinetic properties. Any of the antiepileptic drugs currently used in status epilepticus has all these properties together. An accurate knowledge of the pharmacokinetics is absolutely crucial to rationally decide the route of administration, the loading dose and the maintenance doses. However, pharmacokinetics must only complete, but cannot replace, the clinical experience and judgement, especially because some limitations: kinetic equations are mathematically exact but theoretical; individual kinetics in a given patient is exceptionally known in clinical practice; finally the pharmacokinetics may be significantly modified during a status epilepticus, especially of the generalized convulsive type, due to systemic consequences and complications of the seizures. In the emergency situation of status epilepticus, the correlation between the clinical efficacy and the so-called "therapeutic" plasma levels remains ill defined. The reported values are often very high and their range appears very large. Nevertheless plasma levels are useful, especially for the monitoring of the evolution; they are mandatory for nonlinear-kinetics drugs.

Ketamine controls prolonged status epilepticus

New treatments are needed to control prolonged status epilepticus given the high failure rate of current therapies. In an animal model of status epilepticus based on electrical stimulation of the hippocampus, rats demonstrate at least 5 five-hours of seizure activity following stimulation. Phenobarbital (70 mg/kg) administered 15 min after stimulation effectively controlled seizures in 66% of animals (n=6). When phenobarbital (70 mg/kg) was administered 60 min after stimulation, seizures were controlled in 25% of animals (n=4). Ketamine (100 mg/kg) administered 15 min after stimulation did not control seizures in any animal (n=4). But when ketamine was administered one hour after stimulation it effectively controlled seizures in all animals (n=4). Increasing doses of ketamine were administered 60 min after stimulation to generate a dose-response curve. The ketamine dose response (fraction of seizure free rats) data were fit to a sigmoid curve to derive an ED(50) of 58 mg/kg. These findings suggest that prolonged status epilepticus becomes refractory to phenobarbital but can be effectively controlled by ketamine. For patients experiencing prolonged status epilepticus that is refractory to phenobarbital, ketamine may be an alternative to general anesthesia.

No, some types of nonconvulsive status epilepticus cause little permanent neurologic sequelae (or: "the cure may be worse than the disease")

Nonconvulsive status epilepticus (NCSE) is characterized by a cognitive or behavioral change which lasts for at least 30 minutes, with EEG evidence of seizures. Although there is little argument that generalized nonconvulsive status epilepticus (GNSE) does not cause lasting deficits, there is still debate regarding the morbidity of complex partial status epilepticus (CPSE). Because the EEG is used for diagnosis, a strong argument can be made that NCSE is significantly under-recognized and diagnosed. Furthermore, since the documented cases of permanent neurologic sequelae are few, the potential permanent morbidity from CPSE may be significantly exaggerated. The literature indicates that comatose patients have a poor prognosis largely as a result of comorbid conditions and coma, whereas lightly obtunded or slightly confused patients with NCSE have little or no sequelae. Patients with NCSE may suffer (hypotension and respiratory suppression) from iatrogenic 'aggressive' treatment with intravenous anti-epileptic drugs (IV-AEDs), and the findings in the literature indicate that subjects treated with benzodiazepines may have a worse prognosis. The clinician must balance the potential but rare neurologic morbidity associated with NCSE against the not infrequent morbidity caused by IV-AEDs. Better stratification of the level of consciousness and comorbid conditions is needed when evaluating outcomes so as to clearly distinguish among the deficits due to: comorbid conditions; the effects of treatment and the effects of status epilepticus (SE) proper.

The treatment of convulsive status epilepticus in children. The Status Epilepticus Working Party, Members of the Status Epilepticus Working Party

There is currently little agreement between hospital protocols when treating convulsive status epilepticus in children, and a working party has been set up to produce a national evidence based guideline for treating this condition. This four step guideline is presented in this paper. Its effectiveness will be highlighted and its use audited in a number of centres.

Treatment of epileptic seizures as medical emergencies: a prospective analysis of a decision tree for nonmedically trained staff

The aim of this study was to evaluate the benefit of treating every epileptic seizure as an emergency and to propose a decision tree for use by nonmedical staff. Published literature on emergency medical treatment for seizures was reviewed. A detailed decision tree was developed for use by nonmedical staff. Its effectiveness was prospectively analysed over 16 months. Each seizure was logged, and its duration and severity were recorded. Type, dose, and time of antiepileptic treatment were noted. Results were compared with a 6-month retrospective review. Initiation of antiepileptic drug treatment 5 or 7 minutes after seizure onset was indicated in the tree. Rectal diazepam or lorazepam, or fast-dissolving lorazepam was used. Use of the decision tree resulted in decreased duration of seizures, which lasted up to 18 hours in the retrospective review compared with only 37 minutes in the prospective study. Using this tree, nonmedical staff can appropriately treat adults experiencing seizures. Duration, severity, and frequency of seizures decreased when every seizure was treated as a medical emergency. Implementation of a decision tree is recommended for establishments with patients prone to seizures. It can also be taught to caregivers and parents of patients with well-known epilepsy.

The safety of rapid valproic acid infusion

PURPOSE

The recommended rate of administration of valproic acid injection is 20 mg/min. Drug delivery at this rate may be inadequate for expeditious control of seizures. The safety of rapid infusion of valproic acid has not been established, and this study was designed to explore the effects of rapid infusion in patients with acute seizures.

METHODS

Twenty patients with acute repetitive seizures received 20 mg/kg loading doses of valproic acid. Infusion rates ranged from 33.3 to 555 mg/min (median, 200 mg/min). Sixteen patients had received previous or concomitant antiepileptic drugs, with inadequate seizure control. Heart rate, blood pressure, and respiratory rate were measured before infusion and at frequent intervals for 1 hour after infusion. Patients were also observed for changes in level of alertness and signs of local irritation.

RESULTS

No patient exhibited a decline in level of consciousness or respiratory function. Two patients with significant contributing factors exhibited declines in blood pressure requiring vasopressors. No significant local irritation was reported. Although efficacy was not a measured end point, seizures were abolished in all patients.

CONCLUSIONS

Infusion of valproic acid at rates between 33 and 555 mg/min is well tolerated. No serious adverse effects attributable to the rapid infusion of valproic acid were encountered, although valproic acid, along with other factors, may have contributed to the hypotension in two patients. Intravenous valproic acid is an option for the control of acute seizures.

Status epilepticus: risk factors and complications

Status epilepticus is common and associated with significant mortality and complications. It affects approximately 50 patients per 100,000 population annually and recurs in >13%. History of epilepsy is the strongest single risk factor for generalized convulsive status epilepticus. More than 15% of patients with epilepsy have at least one episode of status epilepticus and low antiepileptic drug levels are a potentially modifiable risk factor. Other risks include young age, genetic predisposition, and acquired brain insults. Fever is a very common risk in children, as is stroke in adults. Mortality rates are 15% to 20% in adults and 3% to 15% in children. Acute complications result from hyperthermia, pulmonary edema, cardiac arrhythmias, and cardiovascular collapse. Long-term complications include epilepsy (20% to 40%), encephalopathy (6% to 15%), and focal neurologic deficits (9% to 11%). Neuronal injury leading to temporal lobe epilepsy is probably mediated by excess excitation via activation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors and consequent elevated intracellular calcium that causes acute necrosis and delayed apoptotic cell death. Some forms of nonconvulsive status epilepticus may also lead to neuronal injury by this mechanism, but others may not. Based on clinical and experimental observations, complex partial status epilepticus is more likely to result in neuronal injury similar to generalized convulsive status epilepticus. Absence status epilepticus is much less likely to result in neuronal injury, and complications because it may be mediated primarily through excess inhibition. Future research strategies to prevent complications of status epilepticus include the study of new drugs (including NMDA antagonists, new drug delivery systems, and drug combinations) to stop seizure activity and prevent acute and delayed neuronal injury that leads to the development of epilepsy.

[The difficulty of defining and classifying status epilepticus]

Status epilepticus (SE) can theoretically be described using a simple definition based on physiopathological mechanisms: any seizure of epileptic nature, partial or generalized, convulsive or non-convulsive, lasting over a period of more than 30 minutes; or repeated seizures lasting for a period of over 30 minutes without recovery of consciousness. In the context of a historical review of various definitions, the validity of this definition is assessed and questioned. The heterogeneous nature of this condition is evidenced in daily clinical practice and by the results of epidemiologic studies. In the present study, the authors propose a more pragmatic and heuristic classification, taking into account not only clinical but also electroencephalographic data, as well as the particular nature of the epileptic syndrome when this is known.

Effect of phenobarbital on seizure frequency and mortality in childhood cerebral malaria: a randomised, controlled intervention study

BACKGROUND

Seizures commonly complicate cerebral malaria and are associated with an increased risk of death and neurological sequelae. We undertook a randomised study to assess the efficacy of intramuscular phenobarbital in preventing seizures in childhood cerebral malaria.

METHODS

Children with cerebral malaria admitted to one hospital in Kilifi, Kenya, were randomly assigned a single intramuscular dose of phenobarbital (20 mg/kg) or identical placebo. Clinical tolerance was assessed at the start of the trial, with particular reference to respiratory depression and hypotension. Seizures were timed and recorded, and treated in a standard way. Plasma phenobarbital concentrations were measured. Analyses were by intention to treat.

FINDINGS

440 children with cerebral malaria were admitted to the hospital; 100 were not recruited to the study. Of the remaining 340, 170 received phenobarbital and 170 placebo. The drug was adequately absorbed and well tolerated. Seizure frequency was significantly lower in the phenobarbital group than in the placebo group (18 [11%] vs 46 [27%] children had three or more seizures of any duration; odds ratio 0.32 [95% CI 0.18-0.58]) but mortality was doubled (30 [18%] vs 14 [8%] deaths; 2.39 [1.28-4.64]). The frequency of respiratory arrest was higher in the phenobarbital group than in the placebo group, and mortality was greatly increased in children who received phenobarbital plus three or more doses of diazepam (odds ratio 31.7 [1.2-814]).

INTERPRETATION

In children with cerebral malaria, phenobarbital 20 mg/kg provides highly effective seizure prophylaxis but is associated with an unacceptable increase in mortality. Use of this dose cannot, therefore, be recommended.

Anesthesia and epilepsy

The patient with epilepsy is an anesthetic challenge. New drugs and surgical procedures are being used to treat epilepsy. Certain anesthetics have been reported to cause perioperative seizures. This discussion will focus on advances in the treatment of epilepsy, as well as the pro- and anti-convulsant effects of the newer anesthetic agents.

Neuroprotective effects of early vs. late administration of dantrolene in experimental status epilepticus

We examined the effects of dantrolene, an inhibitor of intracellular calcium release, on hippocampal neuronal damage associated with 140 min of limbic status epilepticus in the rat. Dantrolene (10 mg/kg i.p.) was administered after either 30 min or 140 min of status epilepticus. Early administration was associated with a significant reduction in the amount of neuronal injury in all hippocampal subregions, while late administration was associated with less neuronal injury in area CA3 only. These findings suggest that a substantial portion of seizure-induced hippocampal injury is associated with release of calcium from intracellular stores, and that early administration of dantrolene may be a useful adjunct to anticonvulsant treatment of status epilepticus.

Convulsive Status Epilepticus

Generalized convulsive status epilepticus (GCSE) is a medical emergency that must be treated rapidly and aggressively to prevent neuronal damage. Treatment should be initiated with intravenous lorazepam, 0.1 mg/kg, given at a rate of no more than 2 mg/min. If convulsions persist for more than 10 minutes or recur more than 20 minutes after lorazepam therapy is started, then fosphenytoin (20 mg of phenytoin equivalents per kilogram) should be infused at a rate of no more than 150 mg/min. If convulsions still continue, intravenous general anesthesia with pentobarbital, benzodiazepine drip, or propofol should be initiated after respiratory support has been established. All patients with GCSE who do not recover consciousness should be monitored with electroencephalography (EEG), and any residual epileptiform activity on EEG, including periodic epileptiform discharges (PEDs), should be considered evidence of continuing GCSE and treated aggressively.

Topiramate reduces neuronal injury after experimental status epilepticus

Prolonged seizures are associated with injury to vulnerable neurons, particularly in the hippocampus. Identification of compounds that attenuate injury after prolonged seizures could be of value in the management of refractory status epilepticus. We hypothesized that topiramate, an anticonvulsant with multiple mechanisms of action, would attenuate hippocampal neuronal injury when given after experimental status epilepticus. Limbic status epilepticus was induced in adult male Wistar rats for 140 min by unilateral hippocampal electrical stimulation. Rats then received intraperitoneal injections of either vehicle (n=6) or topiramate at 20 mg/kg (n=6), 40 mg/kg (n=7) or 80 mg/kg (n=7). Three days later, hippocampal sections were processed for neuronal degeneration using a silver impregnation stain. Seizure-induced damage was assessed by measuring the density of silver staining in hippocampal regions CA1, CA3 and dentate hilus. Administration of topiramate at each dose was associated with a significant reduction in staining density bilaterally in area CA1 and the dentate hilus. Reduction in staining density in area CA3 was seen contralateral to the side of stimulation at the two higher topiramate doses only. The results indicate that administration of topiramate after experimental status epilepticus can attenuate seizure-induced hippocampal neuronal injury.

Management approaches to prolonged seizures and status epilepticus

Status epilepticus (SE) treatment should proceed on four fronts: termination of SE, prevention of recurrence, management of potential precipitating causes, and management of SE complications and underlying conditions. The intensity of the treatment should reflect the risk to the patient from SE, and drugs likely to depress respiration and blood pressure should initially be avoided. The Veterans Administration cooperative trial showed that when treating overt SE, first-line treatment success rates were: lorazepam 64.9%; phenobarbital 58.2%; diazepam/phenytoin 55.8%; and phenytoin alone 43.6%. The aggregate response rate to second-line agents for patients who did not respond to first-line agents was 7.0%, and it was 2.3% for third-line agents, raising the question of the efficacy of a second and third drug. The recommended treatment for generalized convulsive SE is to begin with lorazepam. As a second-line agent, phenytoin or fosphenytoin, is still recommended if SE control is not achieved within 5 to 7 min. Fosphenytoin achieves a free phenytoin level of about 2 micro/mL in 15 min, as opposed to 25 min with phenytoin itself. Moreover, fosphenytoin is safer and, despite higher cost, it may be cost-effective. High-dose barbiturates, high-dose benzodiazepines, and propofol are employed for major treatment for refractory SE. Patients at this stage should undergo continuous electroencephalogram monitoring. Once SE is controlled, prevention of seizure recurrence should be individualized to each patient. The major complications of generalized convulsive SE (GCSE), rhabdomyolysis and hyperthermia, should be watched for and treated.

Nonconvulsive status epilepticus in acute brain injury

Whether or not nonconvulsive status epilepticus produces permanent brain damage is a source of controversy. Contributing to the controversy is the lack of clarity for classifying the clinical and electrographic phenomena that constitute nonconvulsive status epilepticus. Nonconvulsive status epilepticus commonly occurs in the context of an acute brain injury. For example, it commonly persists in generalized convulsive status epilepticus after convulsive activity has stopped, and it is not uncommonly associated with acute cerebral ischemia. Its clinical characteristics are ambiguous, subtle, and nonspecific making the diagnosis difficult. In the absence of EEG testing, it is likely to be missed or delayed. When acute brain injury and nonconvulsive status epilepticus occur concurrently, the severity of acute brain injury has traditionally been accepted as determining patient outcome. However, increasing evidence suggests that the two conditions are synergistically detrimental and increase brain injury. Guidelines remain to be established for the intensity and duration of anticonvulsant therapy in these patients. Evidence suggests that, in the absence of extreme and irreversible acute brain injury, early intensive intervention is necessary to improve the otherwise poor outcome of these patients.