Status epilepticus and the use of continuous EEG monitoring in the intensive care unit

Characteristics of Seizure and Antiepileptic Drug Utilization in Outpatients With Autoimmune Encephalitis

Autoimmune encephalitis (AE) is one kind of encephalitis that associates with specific neuronal antigens. Most patients with AE likely suffer from seizures, but data on the characteristics of seizure and antiepileptic drugs (AEDs) utilization in this patient group remains limited. This study aimed to report the clinical status of seizure and AEDs treatment of patients with AE, and to evaluate the relationship between AEDs discontinuation and seizure outcomes. Patients with acute neurological disorders and anti-N-methyl-D-aspartate receptor (NMDAR), γ-aminobutyric acid B receptor (GABA_BR), leucine-rich glioma inactivated 1, or contactin-associated protein-like 2 (CASPR2) antibodies were included. As patients withdrew from AEDs, they were divided into the early withdrawal (EW, AEDs used ≤3 months) and late withdrawal (LW, AEDs used >3 months) groups. Seizure remission was defined as having no seizures for at least 1 year after the last time when AEDs were administered. Seizure outcomes were assessed on the basis of remission rate. The factors affecting the outcomes were assessed through Spearman analysis. In total, we enrolled 75 patients (39 patients aged <16 years, male/female = 39/36) for follow-up, which included 67 patients with anti-NMDAR encephalitis, 4 patients with anti-GABA_BR encephalitis, 2 patients with anti-voltage-gated potassium channel encephalitis, and 2 patients with coexisting antibodies. Among the 34 enrolled patients with anti-NMDAR encephalitis who were withdrawn from AEDs, only 5.8% relapse was reported during the 1-year follow-up, with no significant difference in the percentage of relapse between the EW and LW groups (P = 0.313). Fifteen patients (an average age of 6.8, 14 patients with anti-NMDAR encephalitis and 1 patient with anti-CASPR2 encephalitis) presented seizure remission without any AEDs. Seventy five percent of patients with anti-GABA_BR antibodies developed refractory seizure. Other risk factors which contributed to refractory seizure and seizure relapse included status epilepticus (P = 0.004) and cortical abnormalities (P = 0.028). Given this retrospective data, patients with AE have a high rate of seizure remission, and the long-term use of AEDs may not be necessary to control the seizure. Moreover, seizures in young patients with anti-NMDAR encephalitis presents self-limited. Patients with anti-GABA_BR antibody, status epilepticus, and cortical abnormalities are more likely to develop refractory seizure or seizure relapse.

Performance of Spectrogram-Based Seizure Identification of Adult EEGs by Critical Care Nurses and Neurophysiologists

PURPOSE

Continuous EEG screening using spectrograms or compressed spectral arrays (CSAs) by neurophysiologists has shorter review times with minimal loss of sensitivity for seizure detection when compared with visual analysis of raw EEG. Limited data are available on the performance characteristics of CSA-based seizure detection by neurocritical care nurses.

METHODS

This is a prospective cross-sectional study that was conducted in two academic neurocritical care units and involved 33 neurointensive care unit nurses and four neurophysiologists.

RESULTS

All nurses underwent a brief training session before testing. Forty two-hour CSA segments of continuous EEG were reviewed and rated for the presence of seizures. Two experienced clinical neurophysiologists masked to the CSA data performed conventional visual analysis of the raw EEG and served as the gold standard. The overall accuracy was 55.7% among nurses and 67.5% among neurophysiologists. Nurse seizure detection sensitivity was 73.8%, and the false-positive rate was 1-per-3.2 hours. Sensitivity and false-alarm rate for the neurophysiologists was 66.3% and 1-per-6.4 hours, respectively. Interrater agreement for seizure screening was fair for nurses (Gwet AC1 statistic: 43.4%) and neurophysiologists (AC1: 46.3%).

CONCLUSIONS

Training nurses to perform seizure screening utilizing continuous EEG CSA displays is feasible and associated with moderate sensitivity. Nurses and neurophysiologists had comparable sensitivities, but nurses had a higher false-positive rate. Further work is needed to improve sensitivity and reduce false-alarm rates.

Characterizing Cefepime Neurotoxicity: A Systematic Review

Neurotoxicity due to cefepime has not been well characterized. We performed a systematic review of the literature and included 5 additional cases from our center. Of the 198 cases found, the mean age was 67 years and 87% of patients had renal dysfunction. The most common clinical features were diminished level of consciousness (80%), disorientation/agitation (47%), and myoclonus (40%). It is worth noting that nonconvulsive status epilepticus was relatively common with 31% of cases, whereas only 11% had convulsive seizures. Single-center estimate of incidence was 1 in 480 courses of cefepime. Cefepime neurotoxicity should be considered in older patients with renal dysfunction and new onset encephalopathy, especially if concurrent myoclonus is present. More work is needed to prospectively assess incidence and outcomes related to cefepime neurotoxicity.

Status Epilepticus and Beyond: A Clinical Review of Status Epilepticus and an Update on Current Management Strategies in Super-refractory Status Epilepticus

Status epilepticus and refractory status epilepticus represent some of the most complex conditions encountered in the neurological intensive care unit. Challenges in management are common as treatment options become limited and prolonged hospital courses are accompanied by complications and worsening patient outcomes. Antiepileptic drug treatments have become increasingly complex. Rational polytherapy should consider the pharmacodynamics and kinetics of medications. When seizures cannot be controlled with medical therapy, alternative treatments, including early surgical evaluation can be considered; however, evidence is limited. This review provides a brief overview of status epilepticus, and a recent update on the management of refractory status epilepticus based on evidence from the literature, evidence-based guidelines, and experiences at our institution.

Diagnostic accuracy between readers for identifying electrographic seizures in critically ill adults

Objective

Electrographic seizures in critically ill patients are often equivocal. In this study, we sought to determine the diagnostic accuracy of electrographic seizure annotation in adult intensive care units (ICUs) and to identify affecting factors.

Methods

To investigate diagnostic accuracy, interreader agreement (IRA) measures were derived from 5,769 unequivocal and 6,263 equivocal seizure annotations by five experienced electroencephalogram (EEG) readers after reviewing 74 days of EEGs from 50 adult ICU patients. Factors including seizure equivocality (unequivocal vs. equivocal) and laterality (generalized, partial, or bilaterally independent), cyclicity (cyclic vs. noncyclic), persistency (occurrence of status epilepticus), and patient consciousness level (coma vs. noncoma) were further investigated for their influence on IRA measures.

Results

On average, 70% of seizures marked by a reference reader overlapped, at least in part, with those marked by a test reader (any-overlap sensitivity, AO-Sn). Agreed seizure duration between reader pairs (overlap-integral sensitivity, OI-Sn) was 62%, while agreed nonseizure duration (overlap-integral specificity, OI-Sp) was 99%. A test reader would annotate one additional seizure not overlapping with a reference reader's annotation in every 11.7 h of EEG, that is, the false-positive rate (FPR) was 0.0854/h. Classifying seizure patterns into unequivocal and equivocal improved specificity and FPR (unequivocal patterns) but compromised sensitivity only for equivocal patterns. Sensitivity of all and unequivocal annotations was higher for patients with status epilepticus. Specificity was higher for partial than for bilaterally independent unequivocal seizure patterns, and lower for cyclic all seizure patterns.

Significance

Diagnosing electrographic seizures in critically ill adults is highly specific and moderately sensitive. Improved criteria for diagnosing electrographic seizures in the ICU are needed.

Predictive Value of Short-Term EEG Recording in Critically ill Adult Patients

We assessed the EEG patterns and their prognostic significance in critically ill adult patients with encephalopathy, by digital EEGs lasting lip to 1 hour Of the 110 patients (age: 43.8 ± 19.4 years, male: female:1.6:1) studied, 32% had hypoxic ischemic encephalopathy (HIE), 17% severe infections, and 14.5% stroke. Observed EEG patterns were diffuse slowing (41%), low-voltage cerebral activity (LVCA, 18%), nonconvulsive status epilepticus (NCSE, 13.6%), and periodic abnormalities (9.1%). LVCA, age, Glasgow Coma Score (GCS) < 8, HIE, and modified Hockaday's EEG grades of IV and V were associated with poor outcome (p < 0.005) at hospital discharge; generalized slowing was associated with a relatively good outcome (p = 0.003). On multivariate analysis, factors independently predictive of mortality were LVCA, older age, and poor GCS. In conclusion, LVCA and generalized background slowing were common EEG patterns among critically ill intensive care unit (ICU) patients with encephalopathy of varied etiologies. While LVCA was associated with a poor outcome, generalized background slowing predicted better prognosis. Conventional short-duration, bedside EEG studies could aid in the recognition of electrographic patterns of prognostic importance in facilities where continuous EEG monitoring is lacking.

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.

Sensitivity of compressed spectral arrays for detecting seizures in acutely ill adults

BACKGROUND

Continuous EEG recordings (cEEGs) are increasingly used in evaluation of acutely ill adults. Pre-screening using compressed data formats, such as compressed spectral array (CSA), may accelerate EEG review. We tested whether screening with CSA can enable detection of seizures and other relevant patterns.

METHODS

Two individuals reviewed the CSA displays of 113 cEEGs. While blinded to the raw EEG data, they marked each visually homogeneous CSA segment. An independent experienced electroencephalographer reviewed the raw EEG within 60 s on either side of each mark and recorded any seizures (and isolated epileptiform discharges, periodic epileptiform discharges (PEDs), rhythmic delta activity (RDA), and focal or generalized slowing). Seizures were considered to have been detected if the CSA mark was within 60 s of the seizure. The electroencephalographer then determined the total number of seizures (and other critical findings) for each record by exhaustive, page-by-page review of the entire raw EEG.

RESULTS

Within each of the 39 cEEG recordings containing seizures, one CSA reviewer identified at least one seizure, while the second CSA reviewer identified 38/39 patients with seizures. The overall detection rate was 89.0 % of 1,190 total seizures. When present, an average of 87.9 % of seizures were detected per individual patient. Detection rates for other critical findings were as follows: epileptiform discharges, 94.0 %; PEDs, 100 %; RDA, 97.9 %; focal slowing, 100 %; and generalized slowing, 100 %.

CONCLUSIONS

CSA-guided review can support sensitive screening of critical pathological information in cEEG recordings. However, some patients with seizures may not be identified.

The epidemiology, risk factors, and impact on hospital mortality of status epilepticus after subdural hematoma in the United States

Introduction

Subdural hematoma (SDH) is a well described risk factor in the development of Status Epilepticus (SE), however the epidemiology of SE after SDH is unknown. In this study, we sought to determine the epidemiology of SE, the prevalence of risk factors, and impact on hospital mortality using a large administrative dataset.

Methods

Data was derived from the Nationwide Inpatient Sample from 1988 through 2011. We queried the NIS database for patients older than 18 years, with a diagnosis of SDH and SE. Diagnoses were defined by ICD 9 CM codes 432.1, 852.2, 852.3 and 345.3 for SE. Adjusted incidence rates of admission and prevalence proportions were calculated. Multivariate logistic models were then fitted to assess for the impact of status epilepticus on hospital mortality.

Results

Over the 23-year period, we identified more than 1,583,255 admissions with a diagnosis of SDH. The prevalence of SE in this cohort was 0.5% (7,421 admissions). The population adjusted incidence rate of admissions of SDH increased from 13/100,000 in 1988 to 38/100,000 in 2011. The prevalence of SE in SDH, increased from 0.5% in 1988 to 0.7% in 2011. In hospital mortality of patients with SDH and without SE decreased from 17.9% to 10.3% while in hospital mortality of patients with SDH and SE did not statistically change. Mortality increased over the same period (2.3/100,000 in 1988 to 3.9/100.000 in 2011) and the diagnosis of SE increased mortality in this cohort (OR 2.17, p < 0.0001). The risk of SE remained stable throughout the study period, but was higher among older patients, blacks, and in those with respiratory, metabolic, hematological, and renal system dysfunction.

Conclusion

Our study demonstrates that the incidence of admissions of SDH is increasing in the United States. Despite a decline in the overall SDH related mortality, SE increased the risk of in-hospital death in patients with a primary diagnosis of SDH.

Anesthetic drugs in status epilepticus: risk or rescue? A 6-year cohort study

OBJECTIVE

To evaluate the risks of continuously administered IV anesthetic drugs (IVADs) on the outcome of adult patients with status epilepticus (SE).

METHODS

All intensive care unit patients with SE from 2005 to 2011 at a tertiary academic medical care center were included. Relative risks were calculated for the primary outcome measures of seizure control, Glasgow Outcome Scale score at discharge, and death. Poisson regression models were used to control for possible confounders and to assess effect modification.

RESULTS

Of 171 patients, 37% were treated with IVADs. Mortality was 18%. Patients with anesthetic drugs had more infections during SE (43% vs 11%; p < 0.0001) and a 2.9-fold relative risk for death (2.88; 95% confidence interval 1.45-5.73), independent of possible confounders (i.e., duration and severity of SE, nonanesthetic third-line antiepileptic drugs, and critical medical conditions) and without significant effect modification by different grades of SE severity and etiologies. As IVADs were used after first- and second-line drugs failed, there was a correlation between treatment-refractory SE and the use of IVADs, leading to insignificant results regarding the risk of IVADs and outcome after additional adjustment for refractory SE.

CONCLUSION

Our findings heighten awareness regarding adverse effects of IVADs. Randomized controlled trials are needed to further clarify the association of IVADs with outcome in patients with SE.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that patients with SE receiving IVADs have a higher proportion of infection and an increased risk of death as compared to patients not receiving IVADs.

Treatment of status epilepticus with ketamine, are we there yet?

Status epilepticus (SE), a neurological emergency both in adults and in children, could lead to brain damage and even death if untreated. Generalized convulsive SE (GCSE) is the most common and severe form, an example of which is that induced by organophosphorus nerve agents. First- and second-line pharmacotherapies are relatively consensual, but if seizures are still not controlled, there is currently no definitive data to guide the optimal choice of therapy. The medical community seems largely reluctant to use ketamine, a noncompetitive antagonist of the N-methyl-d-aspartate glutamate receptor. However, a review of the literature clearly shows that ketamine possesses, in preclinical studies, antiepileptic properties and provides neuroprotection. Clinical evidences are scarcer and more difficult to analyze, owing to a use in situations of polytherapy. In absence of existing or planned randomized clinical trials, the medical community should make up its mind from well-conducted preclinical studies performed on appropriate models. Although potentially active, ketamine has no real place for the treatment of isolated seizures, better accepted drugs being used. Its best usage should be during GCSE, but not waiting for SE to become totally refractory. Concerns about possible developmental neurotoxicity might limit its pediatric use for refractory SE.