Persistent nonconvulsive status epilepticus after the control of convulsive status epilepticus

Outcomes in pediatric patients with nonconvulsive status epilepticus

Recognition of nonconvulsive status epilepticus (NCSE) is gaining increasing attention in the assessment and evaluation of critically ill pediatric patients. The underlying cause of NCSE is often the most important factor in determining outcome. However, there is a growing body of literature suggesting that electrical seizure burden in NCSE also contributes to unfavorable outcomes. Determination of impact of NCSE on outcome based on current evidence involves consideration of heterogeneous study settings, study populations, and process of care and outcome measures. In addition, the lack of data on neurocognitive function prior to episodes of NCSE as well as limited long-term neurocognitive assessment data confines precise conclusions about neurocognitive changes. This article is part of a Special Issue entitled "Status Epilepticus".

Status epilepticus in adults

Status epilepticus is a common neurological emergency with considerable associated health-care costs, morbidity, and mortality. The definition of status epilepticus as a prolonged seizure or a series of seizures with incomplete return to baseline is under reconsideration in an effort to establish a more practical definition to guide management. Clinical research has focused on early seizure termination in the prehospital setting. The approach of early escalation to anaesthetic agents for refractory generalised convulsive status epilepticus, rather than additional trials of second-line anti-epileptic drugs, to avoid neuronal injury and pharmaco-resistance associated with prolonged seizures is gaining momentum. Status epilepticus is also increasingly identified in the inpatient setting as the use of extended electroencephalography monitoring becomes more commonplace. Substantial further research to enable early identification of status epilepticus and efficacy of anti-epileptic drugs will be important to improve outcomes.

Rapid diagnosis of nonconvulsive status epilepticus using reduced-lead electroencephalography

Introduction

Electroencephalography (EEG) is indicated for diagnosing nonconvulsive status epilepticus (NCSE) in a patient who has altered level of consciousness after a motor seizure. A study in a neonatal population found 94% sensitivity and 78% specificity for detection of seizure using a single-lead device. This study aims to show that a reduced montage EEG would detect 90% of seizures detected on standard EEG.

Methods

A portable Brainmaster EEG device was available in the emergency department (ED) at all times. Patients presenting to the ED with altered mental status and known history of seizure or a witnessed seizure having a standard EEG were eligible for this study. The emergency physician obtained informed consent from the legally authorized representative (LAR), while an ED technician attached the electrodes to the patient, and a research associate attached the electrodes to the wiring routing to the portable EEG module. A board-certified epileptologist interpreted the tracings via the Internet. Simultaneously, the emergency physician ordered a standard 23-lead EEG, which would be interpreted by the neurologist on call to read EEGs. We compared the epileptologist’s interpretation of the reduced montage EEG to the results of the 23-lead EEG, which was considered the gold standard for detecting seizures.

Results

Twelve of 12 patients or 100% had the same findings on reduced-montage EEG as standard EEG. One of 12 patients or 8% had nonconvulsive seizure activity.

Conclusion

The results are consistent with prior studies which have shown that 8–48% of patients who have had a motor seizure continue to have nonconvulsive seizure activity on EEG. This study suggests that a bedside reduced-montage EEG can be used to make the diagnosis of NCSE in the ED. Further study will be conducted to see if this technology can be applied to the inpatient neurological intensive care unit setting.

Continuous EEG monitoring in adults in the intensive care unit (ICU)

Continuous EEG monitoring in the ICU is different from planned EEG due to the rather urgent nature of the indications, explaining the fact that recording is started in certain cases by the clinical team in charge of the patient's care. Close collaboration between neurophysiology teams and intensive care teams is essential. Continuous EEG monitoring can be facilitated by quantified analysis systems. This kind of analysis is based on certain signal characteristics, such as amplitude or frequency content, but raw EEG data should always be interpreted if possible, since artefacts can sometimes impair quantified EEG analysis. It is preferable to work within a tele-EEG network, so that the neurophysiologist has the possibility to give an interpretation on call. Continuous EEG monitoring is thus useful in the diagnosis of non-convulsive epileptic seizures or purely electrical discharges and in the monitoring of status epilepticus when consciousness disorders persist after initial treatment. A number of other indications are currently under evaluation.

Inter-rater agreement on identification of electrographic seizures and periodic discharges in ICU EEG recordings

OBJECTIVE

This study investigated inter-rater agreement (IRA) among EEG experts for the identification of electrographic seizures and periodic discharges (PDs) in continuous ICU EEG recordings.

METHODS

Eight board-certified EEG experts independently identified seizures and PDs in thirty 1-h EEG segments which were selected from ICU EEG recordings collected from three medical centers. IRA was compared between seizure and PD identifications, as well as among rater groups that have passed an ICU EEG Certification Test, developed by the Critical Care EEG Monitoring Research Consortium (CCEMRC).

RESULTS

Both kappa and event-based IRA statistics showed higher mean values in identification of seizures compared to PDs (k=0.58 vs. 0.38; p<0.001). The group of rater pairs who had both passed the ICU EEG Certification Test had a significantly higher mean IRA in comparison to rater pairs in which neither had passed the test.

CONCLUSIONS

IRA among experts is significantly higher for identification of electrographic seizures compared to PDs. Additional instruction, such as the training module and certification test developed by the CCEMRC, could enhance this IRA.

SIGNIFICANCE

This study demonstrates more disagreement in the labeling of PDs in comparison to seizures. This may be improved by education about standard EEG nomenclature.

[French guidelines on electroencephalogram]

Electroencephalography allows the functional analysis of electrical brain cortical activity and is the gold standard for analyzing electrophysiological processes involved in epilepsy but also in several other dysfunctions of the central nervous system. Morphological imaging yields complementary data, yet it cannot replace the essential functional analysis tool that is EEG. Furthermore, EEG has the great advantage of being non-invasive, easy to perform and allows control tests when follow-up is necessary, even at the patient's bedside. Faced with the advances in knowledge, techniques and indications, the Société de Neurophysiologie Clinique de Langue Française (SNCLF) and the Ligue Française Contre l'Épilepsie (LFCE) found it necessary to provide an update on EEG recommendations. This article will review the methodology applied to this work, refine the various topics detailed in the following chapters. It will go over the summary of recommendations for each of these chapters and underline proposals for writing an EEG report. Some questions could not be answered by the review of the literature; in those cases, an expert advice was given by the working and reading groups in addition to the guidelines.

A Wavelet-Statistical Features Approach for Nonconvulsive Seizure Detection

The detection of nonconvulsive seizures (NCSz) is a challenge because of the lack of physical symptoms, which may delay the diagnosis of the disease. Many researchers have reported automatic detection of seizures. However, few investigators have concentrated on detection of NCSz. This article proposes a method for reliable detection of NCSz. The electroencephalography (EEG) signal is usually contaminated by various nonstationary noises. Signal denoising is an important preprocessing step in the analysis of such signals. In this study, a new wavelet-based denoising approach using cubical thresholding has been proposed to reduce noise from the EEG signal prior to analysis. Three statistical features were extracted from wavelet frequency bands, encompassing the frequency range of 0 to 8, 8 to 16, 16 to 32, and 0 to 32 Hz. Extracted features were used to train linear classifier to discriminate between normal and seizure EEGs. The performance of the method was tested on a database of nine patients with 24 seizures in 80 hours of EEG recording. All the seizures were successfully detected, and false positive rate was found to be 0.7 per hour.

Continuous EEG monitoring: a survey of neurophysiologists and neurointensivists

OBJECTIVE

Continuous EEG monitoring (cEEG) of critically ill adults is being used with increasing frequency, and practice guidelines on indications for cEEG monitoring have recently been published. However, data describing the current practice of cEEG in critically ill adults is limited. We aimed to describe the current practice of cEEG monitoring in adults in the United States.

METHODS

A survey assessing cEEG indications and procedures was sent to one intensivist and one neurophysiologist responsible for intensive care unit (ICU) cEEG at 151 institutions in the United States. At some institutions only one physician could be identified.

RESULTS

One hundred thirty-seven physicians from 97 institutions completed the survey. Continuous EEG is utilized by nearly all respondents to detect nonconvulsive seizures (NCS) in patients with altered mental status following clinical seizures, intra cerebral hemorrhage (ICH), traumatic brain injury, and cardiac arrest, as well as to characterize abnormal movements suspected to be seizures. The majority of physicians monitor comatose patients for 24-48 h. In an ideal situation with unlimited resources, 18% of respondents would increase cEEG duration. Eighty-six percent of institutions have an on-call EEG technologist available 24/7 for new patient hookups, but only 26% have technologists available 24/7 in-house. There is substantial variability in who reviews EEG and how frequently it is reviewed as well as use of quantitative EEG.

SIGNIFICANCE

Although there is general agreement regarding the indications for ICU cEEG, there is substantial interinstitutional variability in how the procedure is performed.

The probability of seizures during EEG monitoring in critically ill adults

OBJECTIVE

To characterize the risk for seizures over time in relation to EEG findings in hospitalized adults undergoing continuous EEG monitoring (cEEG).

METHODS

Retrospective analysis of cEEG data and medical records from 625 consecutive adult inpatients monitored at a tertiary medical center. Using survival analysis methods, we estimated the time-dependent probability that a seizure will occur within the next 72-h, if no seizure has occurred yet, as a function of EEG abnormalities detected so far.

RESULTS

Seizures occurred in 27% (168/625). The first seizure occurred early (<30min of monitoring) in 58% (98/168). In 527 patients without early seizures, 159 (30%) had early epileptiform abnormalities, versus 368 (70%) without. Seizures were eventually detected in 25% of patients with early epileptiform discharges, versus 8% without early discharges. The 72-h risk of seizures declined below 5% if no epileptiform abnormalities were present in the first two hours, whereas 16h of monitoring were required when epileptiform discharges were present. 20% (74/388) of patients without early epileptiform abnormalities later developed them; 23% (17/74) of these ultimately had seizures. Only 4% (12/294) experienced a seizure without preceding epileptiform abnormalities.

CONCLUSIONS

Seizure risk in acute neurological illness decays rapidly, at a rate dependent on abnormalities detected early during monitoring. This study demonstrates that substantial risk stratification is possible based on early EEG abnormalities.

SIGNIFICANCE

These findings have implications for patient-specific determination of the required duration of cEEG monitoring in hospitalized patients.

Etiology and prognosis of non-convulsive status epilepticus

Although non-convulsive status epilepticus (NCSE) is an important type of epilepsy, it is not often recognized. In order to analyze the clinical characteristics and outcome in patients with NCSE, we examined the medical records of patients with NCSE admitted to the Seoul National University Hospital between June 2005 and October 2008. The clinical details and electroencephalography records of 34 adult NCSE patients (aged over 16 years) were collected. Their mean age was 47 years (standard deviation 20 years, range, 16-87 years), and 20 were female. Twenty-seven patients (79.4%) showed decreased awareness with acute onset, and seven (20.6%) were obtunded or comatose. Ten patients (29.4%) had a history of epilepsy, and four (11.8%) had a history of stroke. NCSE was etiologically attributed to acute medical or neurological problems in 25 patients (73.5%), was cryptogenic in three (8.8%), and was secondary to underlying epilepsy in six (17.7%). Acute symptomatic etiology was associated with poor recovery (p=0.048), with all unresponsive patients in this acute symptomatic group. Eight (23.5%) of the 34 NCSE patients did not recover or died, whereas nine (26.5%) recovered. Our study shows that the presence of acute symptoms or central nervous system infection is associated with poor outcome, suggesting that a high level of vigilance is required to identify and prevent complications.

Usefulness of video-EEG in the paediatric emergency department

Over the past two decades the EEG has technically improved from the use of analog to digital machines and more recently to video-EEG systems. Despite these advances, recording a technically acceptable EEG in an electrically hostile environment such as the emergency department (ED) remains a challenge, particularly with infants or young children. In 1996, a meeting of French experts established a set of guidelines for performing an EEG in the ED based on a review of the available literature. The authors highlighted the most suitable indications for an emergency EEG including clinical suspicion of cerebral death, convulsive and myoclonic status epilepticus, focal or generalized relapsing convulsive seizures as well as follow-up of known convulsive patients. They further recommended emergency EEG in the presence of doubt regarding the epileptic nature of the presentation as well as during the initiation or modification of sedation following brain injury. Subsequently, proposals for expanding the use of EEG in emergency patients have been advocated including trauma, vascular and anoxic-ischemic injury due to cardiorespiratory arrest, postinfective encephalopathy and nonconvulsive status epilepticus. The aim of this review is to show the diagnostic importance of video-EEG, as well as highlighting the predictive prognostic factors for positive and negative outcomes, when utilized in the pediatric ED for seizures as well as other neurological presentations.

Midazolam fails to prevent neurological damage in children with convulsive refractory febrile status epilepticus

BACKGROUND

We conducted a retrospective study to compare the outcome of intravenous midazolam infusion without electroencephalography or targeted temperature management and barbiturate coma therapy with electroencephalography and targeted temperature management for treating convulsive refractory febrile status epilepticus.

PATIENTS

Of 49 consecutive convulsive refractory febrile status epilepticus patients admitted to the pediatric intensive care unit of our hospital, 29 were excluded because they received other treatments or because of various underlying illnesses. Thus, eight patients were treated with midazolam and 10 with barbiturate coma therapy using thiamylal. Midazolam-treated patients were intubated only when necessary, whereas barbiturate coma therapy patients were routinely intubated. Continuous electroencephalography monitoring was utilized only for the barbiturate coma group. The titration goal for anesthesia was clinical termination of status epilepticus in the midazolam group and suppression or burst-suppression patterns on electroencephalography in the barbiturate coma group. Normothermia was maintained using blankets and neuromuscular blockade in the barbiturate coma group and using antipyretics in the midazolam group. Prognoses were measured at 1 month after onset; children were classified into poor and good outcome groups.

RESULTS

Good outcome was achieved in all the barbiturate coma group patients and 50% of the midazolam group patients (P = 0.02, Fisher's exact test).

CONCLUSIONS

Although the sample size was small and our study could not determine which protocol element is essential for the neurological outcome, the findings suggest that clinical seizure control using midazolam without continuous electroencephalography monitoring or targeted temperature management is insufficient in preventing neurological damage in children with convulsive refractory febrile status epilepticus.

Status epilepticus: an update

Status epilepticus (SE) still results in significant mortality and morbidity. Whereas mortality depends mainly on the age of the patient as well as the cause, morbidity is often due to the myriad of complications that occur during prolonged admission to an intensive care environment. Although SE is a clinical diagnosis in most cases (convulsant), its treatment requires support by continuous electroencephalographic recording to ensure cessation of potential nonconvulsive elements of SE. Treatment has recently changed to incorporate four stages and must be initiated at the earliest possible time.

Electrographic seizures after convulsive status epilepticus in children and young adults: a retrospective multicenter study

OBJECTIVE

To describe the prevalence, characteristics, and predictors of electrographic seizures after convulsive status epilepticus (CSE).

STUDY DESIGN

This was a multicenter retrospective study in which we describe clinical and electroencephalographic (EEG) features of children (1 month to 21 years) with CSE who underwent continuous EEG monitoring.

RESULTS

Ninety-eight children (53 males) with CSE (median age of 5 years) underwent subsequent continuous EEG monitoring after CSE. Electrographic seizures (with or without clinical correlate) were identified in 32 subjects (33%). Eleven subjects (34.4%) had electrographic-only seizures, 17 subjects (53.1%) had electroclinical seizures, and 4 subjects (12.5%) had an unknown clinical correlate. Of the 32 subjects with electrographic seizures, 15 subjects (46.9%) had electrographic status epilepticus. Factors associated with the occurrence of electrographic seizures after CSE were a previous diagnosis of epilepsy (P = .029) and the presence of interictal epileptiform discharges (P < .0005). The median (p25-p75) duration of stay in the pediatric intensive care unit was longer for children with electrographic seizures than for children without electrographic seizures (9.5 [3-22.5] vs 2 [2-5] days, Wilcoxon test, Z = 3.916, P = .0001). Four children (4.1%) died before leaving the hospital, and we could not identify a relationship between death and the presence or absence of electrographic seizures.

CONCLUSIONS

After CSE, one-third of children who underwent EEG monitoring experienced electrographic seizures, and among these, one-third experienced entirely electrographic-only seizures. A previous diagnosis of epilepsy and the presence of interictal epileptiform discharges were risk factors for electrographic seizures.

Post-traumatic epilepsy: current and emerging treatment options

Traumatic brain injury (TBI) leads to many undesired problems and complications, including immediate and long-term seizures/epilepsy, changes in mood, behavioral, and personality problems, cognitive and motor deficits, movement disorders, and sleep problems. Clinicians involved in the treatment of patients with acute TBI need to be aware of a number of issues, including the incidence and prevalence of early seizures and post-traumatic epilepsy (PTE), comorbidities associated with seizures and anticonvulsant therapies, and factors that can contribute to their emergence. While strong scientific evidence for early seizure prevention in TBI is available for phenytoin (PHT), other antiepileptic medications, eg, levetiracetam (LEV), are also being utilized in clinical settings. The use of PHT has its drawbacks, including cognitive side effects and effects on function recovery. Rates of recovery after TBI are expected to plateau after a certain period of time. Nevertheless, some patients continue to improve while others deteriorate without any clear contributing factors. Thus, one must ask, 'Are there any actions that can be taken to decrease the chance of post-traumatic seizures and epilepsy while minimizing potential short- and long-term effects of anticonvulsants?' While the answer is 'probably,' more evidence is needed to replace PHT with LEV on a permanent basis. Some have proposed studies to address this issue, while others look toward different options, including other anticonvulsants (eg, perampanel or other AMPA antagonists), or less established treatments (eg, ketamine). In this review, we focus on a comparison of the use of PHT versus LEV in the acute TBI setting and summarize the clinical aspects of seizure prevention in humans with appropriate, but general, references to the animal literature.

[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.

Continuous electroencephalographic monitoring in critically ill patients: indications, limitations, and strategies

OBJECTIVE

Continuous electroencephalography as a bedside monitor of cerebral activity has been used in a range of critically ill patients. This review compiles the indications, limitations, and strategies for continuous electroencephalography in the ICU.

DATA SOURCE

The authors searched the electronic MEDLINE database.

STUDY SELECTION AND DATA EXTRACTION

References from articles of special interest were selected.

DATA SYNTHESIS AND CONCLUSION

Electroencephalographically-defined suppression is routinely used as the basis for titration of pharmacologic therapy in refractory status epilepticus and intracranial hypertension. The increasing use of continuous electroencephalography reveals a clinically underappreciated burden of epileptiform and epileptic activity in patients with primary acute neurologic disorders, and also in critically ill patients with acquired encephalopathy. Status epilepticus is reported with continuous electroencephalography in 1% to 10% of patients with ischemic stroke, 8% to 14% with traumatic brain injury, 10% to 14% with subarachnoid hemorrhage, 1% to 21% with intracerebral hemorrhage, and 30% of patients following cardiorespiratory arrest. These figures underscore the importance of continuous electroencephalography in the critically ill. The interpretation of continuous electroencephalography in the ICU is challenged by electroencephalography artifacts and the frequent subtle differences between ictal and interictal patterns.

Recommendations on the use of EEG monitoring in critically ill patients: consensus statement from the neurointensive care section of the ESICM

OBJECTIVES

Recommendations for EEG monitoring in the ICU are lacking. The Neurointensive Care Section of the ESICM assembled a multidisciplinary group to establish consensus recommendations on the use of EEG in the ICU.

METHODS

A systematic review was performed and 42 studies were included. Data were extracted using the PICO approach, including: (a) population, i.e. ICU patients with at least one of the following: traumatic brain injury, subarachnoid hemorrhage, intracerebral hemorrhage, stroke, coma after cardiac arrest, septic and metabolic encephalopathy, encephalitis, and status epilepticus; (b) intervention, i.e. EEG monitoring of at least 30 min duration; (c) control, i.e. intermittent vs. continuous EEG, as no studies compared patients with a specific clinical condition, with and without EEG monitoring; (d) outcome endpoints, i.e. seizure detection, ischemia detection, and prognostication. After selection, evidence was classified and recommendations developed using the GRADE system.

RECOMMENDATIONS

The panel recommends EEG in generalized convulsive status epilepticus and to rule out nonconvulsive seizures in brain-injured patients and in comatose ICU patients without primary brain injury who have unexplained and persistent altered consciousness. We suggest EEG to detect ischemia in comatose patients with subarachnoid hemorrhage and to improve prognostication of coma after cardiac arrest. We recommend continuous over intermittent EEG for refractory status epilepticus and suggest it for patients with status epilepticus and suspected ongoing seizures and for comatose patients with unexplained and persistent altered consciousness.

CONCLUSIONS

EEG monitoring is an important diagnostic tool for specific indications. Further data are necessary to understand its potential for ischemia assessment and coma prognostication.

Episodes of status epilepticus in young adults: etiologic factors, subtypes, and outcomes

The aim of this study was to evaluate the type, duration, etiology, treatment, and outcome of status epilepticus (SE) episodes, among patients aged 16-50 years. A total of 101 SE episodes in 88 young adult patients fulfilled our criteria. The mean age was 32 years. Status epilepticus episodes were most frequently observed in patients 21-30 years of age. A total of 53% of the patients were male, and 57% had pre-existing epilepsy. Seventy of the 101 episodes were convulsive SE. The most common etiology was withdrawal of or change in antiepileptic drugs (AEDs), seen in 31% of the SE episodes. This study included treatment of SE with traditional AEDs. Sixty-six episodes were treated successfully with intravenous infusion of 18-mg/kg phenytoin, and six episodes were treated with 10-mg/kg phenytoin. A total of 28% of the SE episodes remained refractory to first-line treatment, which was related to the duration of SE and mortality. The outcome was death in 14% of the patients due to underlying etiologies in the hospital.

Calculating the risk benefit equation for aggressive treatment of non-convulsive status epilepticus

OBJECTIVE

To address the question: does non-convulsive status epilepticus warrant the same aggressive treatment as convulsive status epilepticus?

METHODS

We used a decision model to evaluate the risks and benefits of treating non-convulsive status epilepticus with intravenous anesthetics and ICU-level aggressive care. We investigated how the decision to use aggressive versus non-aggressive management for non-convulsive status epilepticus impacts expected patient outcome for four etiologies: absence epilepsy, discontinued antiepileptic drugs, intraparenchymal hemorrhage, and hypoxic ischemic encephalopathy. Each etiology was defined by distinct values for five key parameters: baseline mortality rate of the inciting etiology; efficacy of non-aggressive treatment in gaining control of seizures; the relative contribution of seizures to overall mortality; the degree of excess disability expected in the case of delayed seizure control; and the mortality risk of aggressive treatment.

RESULTS

Non-aggressive treatment was favored for etiologies with low morbidity and mortality such as absence epilepsy and discontinued antiepileptic drugs. The risk of aggressive treatment was only warranted in etiologies where there was significant risk of seizure-induced neurologic damage. In the case of post-anoxic status epilepticus, expected outcomes were poor regardless of the treatment chosen. The favored strategy in each case was determined by strong interactions of all five model parameters.

CONCLUSIONS

Determination of the optimal management approach to non-convulsive status epilepticus is complex and is ultimately determined by the inciting etiology.

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.

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.

Absence of early epileptiform abnormalities predicts lack of seizures on continuous EEG

OBJECTIVE

To determine whether the absence of early epileptiform abnormalities predicts absence of later seizures on continuous EEG monitoring of hospitalized patients.

METHODS

We retrospectively reviewed 242 consecutive patients without a prior generalized convulsive seizure or active epilepsy who underwent continuous EEG monitoring lasting at least 18 hours for detection of nonconvulsive seizures or evaluation of unexplained altered mental status. The findings on the initial 30-minute screening EEG, subsequent continuous EEG recordings, and baseline clinical data were analyzed. We identified early EEG findings associated with absence of seizures on subsequent continuous EEG.

RESULTS

Seizures were detected in 70 (29%) patients. A total of 52 patients had their first seizure in the initial 30 minutes of continuous EEG monitoring. Of the remaining 190 patients, 63 had epileptiform discharges on their initial EEG, 24 had triphasic waves, while 103 had no epileptiform abnormalities. Seizures were later detected in 22% (n = 14) of studies with epileptiform discharges on their initial EEG, vs 3% (n = 3) of the studies without epileptiform abnormalities on initial EEG (p < 0.001). In the 3 patients without epileptiform abnormalities on initial EEG but with subsequent seizures, the first epileptiform discharge or electrographic seizure occurred within the first 4 hours of recording.

CONCLUSIONS

In patients without epileptiform abnormalities during the first 4 hours of recording, no seizures were subsequently detected. Therefore, EEG features early in the recording may indicate a low risk for seizures, and help determine whether extended monitoring is necessary.

Generalized periodic discharges in the critically ill: a case-control study of 200 patients

OBJECTIVE

Generalized periodic discharges are increasingly recognized on continuous EEG monitoring, but their relationship to seizures and prognosis remains unclear.

METHODS

All adults with generalized periodic discharges from 1996 to 2006 were matched 1:1 to controls by age, etiology, and level of consciousness. Overall, 200 patients with generalized periodic discharges were matched to 200 controls.

RESULTS

Mean age was 66 years (range 18-96); 56% were comatose. Presenting illnesses included acute brain injury (44%), acute systemic illness (38%), cardiac arrest (15%), and epilepsy (3%). A total of 46% of patients with generalized periodic discharges had a seizure during their hospital stay (almost half were focal), vs 34% of controls (p = 0.014). Convulsive seizures were seen in a third of both groups. A total of 27% of patients with generalized periodic discharges had nonconvulsive seizures, vs 8% of controls (p < 0.001); 22% of patients with generalized periodic discharges had nonconvulsive status epilepticus, vs 7% of controls (p < 0.001). In both groups, approximately half died or were in a vegetative state, one-third had severe disability, and one-fifth had moderate to no disability. Excluding cardiac arrest patients, generalized periodic discharges were associated with increased mortality on univariate analysis (36.8% vs 26.9%; p = 0.049). Multivariate predictors of worse outcome were cardiac arrest, coma, nonconvulsive status epilepticus, and sepsis, but not generalized periodic discharges.

CONCLUSION

Generalized periodic discharges were strongly associated with nonconvulsive seizures and nonconvulsive status epilepticus. While nonconvulsive status epilepticus was independently associated with worse outcome, generalized periodic discharges were not after matching for age, etiology, and level of consciousness.

Modern electroencephalography

Electroencephalography (EEG) has been in continuous development over at least 70 years and is firmly established as a tool in the management of epilepsy. For a while, the technique fell into disregard because of difficulties with interpretation, specificity and sensitivity. Whilst clinicians have to be aware of these problems, they have been largely addressed by recent computer digitization of signals, which permits longer standard recordings and monitoring linked to a simultaneous video. These techniques are not only an essential component of a specialist epilepsy service, where inpatient video-EEG telemetry is vital both for diagnosis and assessment before neurosurgical treatment, but also in general and acute medical settings, particularly for the management of status epilepticus. Further developments in computing will extend the use of EEG in all of these roles and long-term monitoring for diagnosis and management of coma will become more widely available.