Predictors of awakening from postanoxic status epilepticus after therapeutic hypothermia

Prospective Cohort Study Evaluating the Prognostic Value of Simple EEG Parameters in Postanoxic Coma

We prospectively studied early bedside standard EEG characteristics in 61 acute postanoxic coma patients. Five simple EEG features, namely, isoelectric, discontinuous, nonreactive to intense auditory and nociceptive stimuli, dominant delta frequency, and occurrence of paroxysms were classified yes or no. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic curve (AUC) of each of these variables for predicting an unfavorable outcome, defined as death, persistent vegetative state, minimally conscious state, or severe neurological disability, as assessed 1 year after coma onset were computed as well as Synek's score. The outcome was unfavorable in 56 (91.8%) patients. Sensitivity, specificity, PPV, NPV, and AUC of nonreactive EEG for predicting an unfavorable outcome were 84%, 80%, 98%, 31%, and 0.82, respectively; and were all very close to the ones of Synek score>3, which were 82%, 80%, 98%, 29%, and 0.81, respectively. Specificities for predicting an unfavorable outcome were 100% for isoelectric, discontinuous, or dominant delta activity EEG. These 3 last features were constantly associated to unfavorable outcome. Absent EEG reactivity strongly predicted an unfavorable outcome in postanoxic coma, and performed as accurate as a Synek score>3. Analyzing characteristics of some simple EEG features may easily help nonneurophysiologist physicians to investigate prognostic issue of postanoxic coma patient. In this study (a) discontinuous, isoelectric, or delta-dominant EEG were constantly associated with unfavorable outcome and (b) nonreactive EEG performed prognostic as accurate as a Synek score>3.

Clinical, Electroencephalographic, and Neuroradiological Outcome Predictors in Acute Nonhypoxic Encephalopathy: A Nine-Year Cohort Study

Marked impairment of consciousness, brain lesion on neuroimaging, and nonreactive electroencephalographic (EEG) background activity are established outcome predictors in patients with hypoxic encephalopathy. In this observational cohort study, we aimed to assess the predictive value of clinical, neuroimaging and EEG characteristics for outcome in different types of acute nonhypoxic encephalopathic patients. All adult intensive care unit patients from a tertiary academic medical care center with clinical and EEG evidence of acute nonhypoxic encephalopathy were included from 2004 to 2012. Clinical data, neuroimaging studies, EEG characteristics, and outcome were assessed. In-hospital death was the main outcome. Median age of 262 patients was 65 years (range 18-98 years). Mortality was 12.6%. In Poisson regression analyses, older age (P=.02), intracranial hemorrhage (P=.008), coma (P=.012), and nonreactive EEG background activity (P<.0001) were independently associated with death with nonreactive EEG being the strongest predictor (relative risk 3.74; 95% confidence interval 2.02-6.91). Subgroup analysis revealed no significant effect modification for the predictive value of nonreactive EEG by the presence or absence of coma and different types of acute brain lesions. In conclusion, this study identifies and quantifies the independent predictive value of older age, intracranial hemorrhage, coma, and nonreactive EEG for death, in patients with different types of acute nonhypoxic encephalopathy. These results add further credence to the limited body of evidence that EEG provides important prognostic information in different types of acute encephalopathy not related to hypoxic brain injury. Further studies are warranted to analyze the robustness of this predictor in larger subpopulations with specific etiologies of acute nonhypoxic encephalopathies.

Electrophysiologic monitoring in acute brain injury

To determine the optimal use and indications of electroencephalography (EEG) in critical care management of acute brain injury (ABI). An electronic literature search was conducted for articles in English describing electrophysiological monitoring in ABI from January 1990 to August 2013. A total of 165 studies were included. EEG is a useful monitor for seizure and ischemia detection. There is a well-described role for EEG in convulsive status epilepticus and cardiac arrest (CA). Data suggest EEG should be considered in all patients with ABI and unexplained and persistent altered consciousness and in comatose intensive care unit (ICU) patients without an acute primary brain condition who have an unexplained impairment of mental status. There remain uncertainties about certain technical details, e.g., the minimum duration of EEG studies, the montage, and electrodes. Data obtained from both EEG and EP studies may help estimate prognosis in ABI patients, particularly following CA and traumatic brain injury. Data supporting these recommendations is sparse, and high quality studies are needed. EEG is used to monitor and detect seizures and ischemia in ICU patients and indications for EEG are clear for certain disease states, however, uncertainty remains on other applications.

Electrophysiological Monitoring of Brain Injury and Recovery after Cardiac Arrest

Reliable prognostic methods for cerebral functional outcome of post cardiac-arrest (CA) patients are necessary, especially since therapeutic hypothermia (TH) as a standard treatment. Traditional neurophysiological prognostic indicators, such as clinical examination and chemical biomarkers, may result in indecisive outcome predictions and do not directly reflect neuronal activity, though they have remained the mainstay of clinical prognosis. The most recent advances in electrophysiological methods--electroencephalography (EEG) pattern, evoked potential (EP) and cellular electrophysiological measurement--were developed to complement these deficiencies, and will be examined in this review article. EEG pattern (reactivity and continuity) provides real-time and accurate information for early-stage (particularly in the first 24 h) hypoxic-ischemic (HI) brain injury patients with high sensitivity. However, the signal is easily affected by external stimuli, thus the measurements of EP should be combined with EEG background to validate the predicted neurologic functional result. Cellular electrophysiology, such as multi-unit activity (MUA) and local field potentials (LFP), has strong potential for improving prognostication and therapy by offering additional neurophysiologic information to understand the underlying mechanisms of therapeutic methods. Electrophysiology provides reliable and precise prognostication on both global and cellular levels secondary to cerebral injury in cardiac arrest patients treated with TH.

Generalized epileptiform discharges in postanoxic encephalopathy: Quantitative characterization in relation to outcome

OBJECTIVE

Electrographic status epilepticus is observed in 10-35% of patients with postanoxic encephalopathy. It remains unclear which electrographic seizure patterns indicate possible recovery, and which are a mere reflection of severe ischemic encephalopathy, where treatment would be futile. We aimed to identify quantitative electroencephalography (EEG) features with prognostic significance.

METHODS

From continuous EEG recordings of 47 patients with generalized electrographic status epilepticus after cardiac arrest, 5-min epochs were selected every hour. Epochs were visually assessed and categorized into seven categories, including epileptiform discharges. Five quantitative measures were extracted, reflecting background continuity, discharge frequency, discharge periodicity, relative discharge power, and interdischarge waveform correlation. The best achieved outcome within 6 months after cardiac arrest was categorized as "good" (Cerebral Performance Category 1-2, i.e., no or moderate neurologic disability) or "poor" (CPC 3-5, i.e., severe disability, coma, or death).

RESULTS

Ten patients (22%) had a good outcome. Status epilepticus in patients with good outcome started later (45 vs. 29 h after cardiac arrest, p < 0.001), more often ceased for at least 12 h (90% vs. 16%, p = 0.02), and was less often treated with antiepileptic drugs (30% vs. 73%, p = 0.02). Status epilepticus in patients with a good outcome always evolved from a continuous background pattern, as opposed to evolution from a discontinuous background pattern in 14 patients (38%) with a poor outcome. Epileptiform patterns of patients with good outcome had higher background continuity (1.00 vs. 0.83, p < 0.001), higher discharge frequency (1.63 vs. 0.90 Hz, p = 0.002), lower relative discharge power (0.29 vs. 0.40, p = 0.01), and lower discharge periodicity (0.32 vs. 0.45, p = 0.04).

SIGNIFICANCE

Our results can be used to identify patients with possible recovery. We speculate that quantitative features associated with poor outcome reflect low neural network complexity, resulting from extensive ischemic damage.

Neuroprotective strategies and neuroprognostication after cardiac arrest

Neurocognitive disturbances are common among survivors of cardiac arrest (CA). Although initial management of CA, including bystander cardiopulmonary resuscitation, optimal chest compression, and early defibrillation, has been implemented continuously over the last years, few therapeutic interventions are available to minimize or attenuate the extent of brain injury occurring after the return of spontaneous circulation. In this review, we discuss several promising drugs that could provide some potential benefits for neurological recovery after CA. Most of these drugs have been investigated exclusively in experimental CA models and only limited clinical data are available. Further research, which also considers combined neuroprotective strategies that target multiple pathways involved in the pathophysiology of postanoxic brain injury, is certainly needed to demonstrate the effectiveness of these interventions in this setting. Moreover, the evaluation of neurological prognosis of comatose patients after CA remains an important challenge that requires the accurate use of several tools. As most patients with CA are currently treated with targeted temperature management (TTM), combined with sedative drug therapy, especially during the hypothermic phase, the reliability of neurological examination in evaluating these patients is delayed to 72-96 h after admission. Thus, additional tests, including electrophysiological examinations, brain imaging and biomarkers, have been largely implemented to evaluate earlier the extent of brain damage in these patients.

Neuron specific enolase and Glasgow motor score remain useful tools for assessing neurological prognosis after out-of-hospital cardiac arrest treated with therapeutic hypothermia

AIM OF THE STUDY

Identifying clinical, electrophysiological and biological predictors for 6-month neurological outcome in survivors at day 3 after cardiac arrest (CA) treated with therapeutic hypothermia (TH).

METHODS

We conducted a retrospective cohort study of adults comatose after out-of hospital CA treated with TH. All data were collected from medical charts and laboratory files.

RESULTS

Between January 2010 and March 2013, among the 130 analysed CA survivors, 27 (21%) had a good neurological outcome at 6 months and 103 (79%) had a poor neurological outcome, including 98 deaths. The Glasgow coma score motor response (GCS-M), pupillary reflexes and Neuron Specific Enolase (NSE) were the three best predictors of neurological outcome (P<0.0001). The area under the Receiver Operating Characteristic curve for NSE was 0.92 [0.84-0.99].

CONCLUSION

NSE values, GCS-M scores and pupillary reflexes are the best predictors of poor 6-month outcome after out-of-hospital CA treated with TH. Of these, NSE values have the best-isolated prognostic performance when above 28.8μg/L.

Continuous Amplitude-Integrated Electroencephalographic Monitoring Is a Useful Prognostic Tool for Hypothermia-Treated Cardiac Arrest Patients

Supplemental Digital Content is available in the text.

Modern treatments have improved the survival rate following cardiac arrest, but prognostication remains a challenge. We examined the prognostic value of continuous electroencephalography according to time by performing amplitude-integrated electroencephalography on patients with cardiac arrest receiving therapeutic hypothermia.

Use of perampanel in one case of super-refractory hypoxic myoclonic status: Case report

Proper treatment of hypoxic myoclonic status is not clearly determined. Induced hypothermia is improving prognosis and a more aggressive treatment might be beneficial in some patients. Among the new options of antiepileptic drugs, perampanel (PER) is a drug with a novel mechanism, and it might be a promising drug for myoclonic status or as an antimyoclonic drug. We describe the use of PER in one patient with hypoxic super-refractory myoclonic status.

Description

A 51-year-old patient presented after an out-of-hospital cardiac arrest due to an acute myocardial infarction. The patient was diagnosed with clinical and electrical (EEG) myoclonic status at the rewarming phase. Several treatments were used, starting with clonazepam, valproate, sedation (midazolam, propofol), and subsequently barbiturate-induced coma with persistent myoclonic status. Finally, we decided to try PER (dose: 6–8 mg) through a nasogastric tube, resulting in a marked improvement of EEG activity and myoclonus decrease. The patient had a progressive clinical improvement, with a CPC (Cerebral Performance Category) scale score of 1.

Conclusion

This case shows the potential utility of PER as a therapeutic option in super-refractory hypoxic status and even its potential use before other aggressive alternatives considering their greater morbidity.

Generalized periodic discharges: Pathophysiology and clinical considerations

Generalized periodic discharges (GPDs) are commonly encountered in metabolic encephalopathy and cerebral hypoxia/ischemia. The clinical significance of this EEG pattern is indistinct, and it is unclear whether treatment with antiepileptic drugs is beneficial. In this study, we discuss potential pathophysiological mechanisms. Based on the literature, supplemented with simulations in a minimal computational model, we conclude that selective synaptic failure or neuronal damage of inhibitory interneurons, leading to disinhibition of excitatory pyramidal cells, presumably plays a critical role. Reversibility probably depends on the potential for functional recovery of these interneurons. Whether antiepileptic drugs are helpful for regaining function is unclear. This article is part of a Special Issue entitled "Status Epilepticus".

Which EEG patterns in coma are nonconvulsive status epilepticus?

Nonconvulsive status epilepticus (NCSE) is common in patients with coma with a prevalence between 5% and 48%. Patients in deep coma may exhibit epileptiform EEG patterns, such as generalized periodic spikes, and there is an ongoing debate about the relationship of these patterns and NCSE. The purposes of this review are (i) to discuss the various EEG patterns found in coma, its fluctuations, and transitions and (ii) to propose modified criteria for NCSE in coma. Classical coma patterns such as diffuse polymorphic delta activity, spindle coma, alpha/theta coma, low output voltage, or burst suppression do not reflect NCSE. Any ictal patterns with a typical spatiotemporal evolution or epileptiform discharges faster than 2.5 Hz in a comatose patient reflect nonconvulsive seizures or NCSE and should be treated. Generalized periodic diacharges or lateralized periodic discharges (GPDs/LPDs) with a frequency of less than 2.5 Hz or rhythmic discharges (RDs) faster than 0.5 Hz are the borderland of NCSE in coma. In these cases, at least one of the additional criteria is needed to diagnose NCSE (a) subtle clinical ictal phenomena, (b) typical spatiotemporal evolution, or (c) response to antiepileptic drug treatment. There is currently no consensus about how long these patterns must be present to qualify for NCSE, and the distinction from nonconvulsive seizures in patients with critical illness or in comatose patients seems arbitrary. The Salzburg Consensus Criteria for NCSE [1] have been modified according to the Standardized Terminology of the American Clinical Neurophysiology Society [2] and validated in three different cohorts, with a sensitivity of 97.2%, a specificity of 95.9%, and a diagnostic accuracy of 96.3% in patients with clinical signs of NCSE. Their diagnostic utility in different cohorts with patients in deep coma has to be studied in the future. This article is part of a Special Issue entitled "Status Epilepticus".

Outcome following postanoxic status epilepticus in patients with targeted temperature management after cardiac arrest

BACKGROUND

Postanoxic electrographic status epilepticus (ESE) is considered a predictor of poor outcome in resuscitated patients after cardiac arrest (CA). Observational data suggest that a subgroup of patients may have a good outcome. This study aimed to describe the prevalence of ESE and potential clinical and electrographic prognostic markers.

METHODS

In this retrospective single study, we analyzed consecutive patients who suffered from CA, and who received temperature management and were monitored with simplified continuous EEG (cEEG) during a five-year period. The patients' charts and cEEG data were initially screened to identify patients with clinical seizures or ESE. The cEEG diagnosis of ESE was retrospectively reanalyzed according to strict criteria by a neurophysiologist blinded to patient outcome. The EEG background patterns prior to the onset of ESE, duration of ESE, presence of clinical seizures, and use of antiepileptic drugs were analyzed. The results of somatosensory-evoked potentials (SSEPs) and neuron-specific enolase (NSE) at 48 h after CA were described in all patients with ESE. Antiepileptic treatment strategies were not protocolized. Outcome was evaluated using the Cerebral Performance Category (CPC) scale at 6 months, and good outcome was defined as CPC 1-2.

RESULTS

Of 127 patients, 41 (32%) developed ESE. Twenty-five patients had a discontinuous EEG background prior to ESE, and all died without regaining consciousness. Sixteen patients developed a continuous EEG background prior to the start of ESE, four of whom survived, three with CPC 1-2 and one with CPC 3 at 6 months. Among survivors, ESE developed at a median of 46 h after CA. All had preserved N20 peaks on SSEP and NSE values of 18-37 μg/l.

CONCLUSION

Electrographic status epilepticus is common among comatose patients after cardiac arrest, with few survivors. A combination of a continuous EEG background prior to ESE, preserved N20 peaks on SSEPs, and low or moderately elevated NSE levels may indicate a good outcome. This article is part of a Special Issue entitled "Status Epilepticus".

Adverse events associated with poor neurological outcome during targeted temperature management and advanced critical care after out-of-hospital cardiac arrest

Introduction

The aim of this study was to investigate the association of adverse events (AEs) during targeted temperature management (TTM) and other AEs and concomitant treatments during the advanced critical care period with poor neurological outcome at hospital discharge in adult out-of-hospital cardiac arrest (OHCA) patients.

Methods

This was a retrospective study using Korean Hypothermia Network registry data of adult OHCA patients treated with TTM in 24 teaching hospitals throughout South Korea from 2007 to 2012. Demographic characteristics, resuscitation and post-resuscitation variables, AEs, and concomitant treatments during TTM and the advanced critical care were collected. The primary outcome was poor neurological outcome, defined as a cerebral performance category (CPC) score of 3–5 at hospital discharge. The AEs and concomitant treatments were individually entered into the best multivariable predictive model of poor neurological outcome to evaluate the associations between each variable and outcome.

Results

A total of 930 patients, including 704 for whom a complete dataset of AEs and covariates was available for multivariable modeling, were included in the analysis; 476 of these patients exhibited poor neurological outcome [CPC 3 = 50 (7.1 %), CPC 4 = 214 (30.4 %), and CPC 5 = 212 (30.1 %)]. Common AEs included hyperglycemia (45.6 %), hypokalemia (31.3 %), arrhythmia (21.3 %) and hypotension (29 %) during cooling, and hypotension (21.6 %) during rewarming. Bleeding (5 %) during TTM was a rare AE. Common AEs during the advanced critical care included pneumonia (39.6 %), myoclonus (21.9 %), seizures (21.7 %) and hypoglycemia within 72 hours (23 %). After adjusting for independent predictors of outcome, cooling- and rewarming-related AEs were not significantly associated with poor neurological outcome. However, sepsis, myoclonus, seizure, hypoglycemia within 72 hours and anticonvulsant use during the advanced critical care were associated with poor neurological outcome [adjusted odds ratios (95 % confidence intervals) of 3.12 (1.40–6.97), 3.72 (1.93–7.16), 4.02 (2.04–7.91), 2.03 (1.09–3.78), and 1.69 (1.03–2.77), respectively]. Alternatively, neuromuscular blocker use was inversely associated with poor neurological outcome (0.48 [0.28–0.84]).

Conclusions

Cooling- and rewarming-related AEs were not associated with poor neurological outcome at hospital discharge. Sepsis, myoclonus, seizure, hypoglycemia within 72 hours and anticonvulsant use during the advanced critical care period were associated with poor neurological outcome at hospital discharge in our study.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0991-9) contains supplementary material, which is available to authorized users.

Characteristics and role in outcome prediction of continuous EEG after status epilepticus: A prospective observational cohort

OBJECTIVE

Continuous electroencephalography (cEEG) is important for treatment guidance in status epilepticus (SE) management, but its role in clinical outcome prediction is unclear. Our aim is to determine which cEEG features give independent outcome information after correction for clinical predictor.

METHODS

cEEG data of 120 consecutive adult patients with SE were prospectively collected in three academic medical centers using the 2012 American Clinical Neurophysiology Society's Standardized Critical Care EEG Terminology. Association between cEEG features and two clinical outcome measures (mortality and complete recovery) was assessed.

RESULTS

In the first 24 h of EEG recording, 49 patients (40.8%) showed no periodic or rhythmic pattern, 45 (37.5%) had periodic discharges, 20 (16.7%) had rhythmic delta activity, and 6 (5%) had spike-and-wave discharges. Seizures were recorded in 68.3% of patients. After adjusting for known clinical predictive factors for mortality including the STatus Epilepticus Severity Score (STESS) and the presence of a potentially fatal etiology, the only EEG features (among rhythmic and periodic patterns, seizures, and background activity) that remained significantly associated with outcome were the absence of a posterior dominant rhythm (odds ratio [OR] 9.8; p = 0.033) for mortality and changes in stage II sleep pattern characteristics (OR 2.59 for each step up among these categories: absent, present and abnormal, present and normal; p = 0.002) for complete recovery.

SIGNIFICANCE

After adjustment for relevant clinical findings, including SE severity and etiology, cEEG background information (posterior dominant rhythm and sleep patterns) is more predictive for clinical outcome after SE than are rhythmic and periodic patterns or seizures.

Malignant EEG patterns in cardiac arrest patients treated with targeted temperature management who survive to hospital discharge

BACKGROUND AND PURPOSE

Cardiac arrest patients treated with targeted temperature management (TTM) have improved neurological outcomes, however mortality remains high. EEG monitoring improves detection of malignant EEG patterns (MEPs), however their prevalence in patients surviving to hospital discharge is unknown.

DESIGN/METHODS

We examined consecutive cardiac arrest subjects who received TTM and continuous EEG monitoring at one academic center. Only subjects surviving to hospital discharge were included in the analysis. MEPs were defined as seizures, status epilepticus, myoclonic status epilepticus, or generalized periodic discharges. Subjects with suppression-burst (SB) without concomitant MEPs were categorized as having a "pure" SB pattern. Demographic, survival, hospital discharge disposition, and neurological function data were recorded retrospectively. Outcomes were assessed using the Glasgow-Pittsburgh Cerebral Performance Category (CPC). A CPC score of 1-2 was considered "good" neurological function, and a CPC of 3-4 "poor".

RESULTS

Of 364 admissions due to cardiac arrest screened, 120 (29.9%) survived to hospital discharge and met inclusion criteria. MEPs and pure SB were observed in 19 (15.8%) and 22 (18.3%) survivors respectively. Two subjects with MEP and eight subjects with pure SB had good neurological function at discharge, however all SB cases were confounded by the use of anesthetic agents. Presence of MEPs was not an independent predictor of poor neurological function (p=0.1).

CONCLUSIONS

MEPs are common among cardiac arrest patients treated with induced hypothermia who survive to hospital discharge. Poor neurological function at discharge was not associated with MEPs. Prospective studies assessing the role of EEG monitoring in cardiac arrest prognostication are warranted.

Prognostication in comatose survivors of cardiac arrest: an advisory statement from the European Resuscitation Council and the European Society of Intensive Care Medicine

Objectives

To review and update the evidence on predictors of poor outcome (death, persistent vegetative state or severe neurological disability) in adult comatose survivors of cardiac arrest, either treated or not treated with controlled temperature, to identify knowledge gaps and to suggest a reliable prognostication strategy.

Methods

GRADE-based systematic review followed by expert consensus achieved using Web-based Delphi methodology, conference calls and face-to-face meetings. Predictors based on clinical examination, electrophysiology, biomarkers and imaging were included.

Results and conclusions

Evidence from a total of 73 studies was reviewed. The quality of evidence was low or very low for almost all studies. In patients who are comatose with absent or extensor motor response at ≥72 h from arrest, either treated or not treated with controlled temperature, bilateral absence of either pupillary and corneal reflexes or N20 wave of short-latency somatosensory evoked potentials were identified as the most robust predictors. Early status myoclonus, elevated values of neuron-specific enolase at 48–72 h from arrest, unreactive malignant EEG patterns after rewarming, and presence of diffuse signs of postanoxic injury on either computed tomography or magnetic resonance imaging were identified as useful but less robust predictors. Prolonged observation and repeated assessments should be considered when results of initial assessment are inconclusive. Although no specific combination of predictors is sufficiently supported by available evidence, a multimodal prognostication approach is recommended in all patients.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-014-3470-x) contains supplementary material, which is available to authorized users.

Treatment of electroencephalographic status epilepticus after cardiopulmonary resuscitation (TELSTAR): study protocol for a randomized controlled trial

Background

Electroencephalographic (EEG) status epilepticus is described in 10 to 35% of patients with postanoxic encephalopathy after successful cardiopulmonary resuscitation and is associated with case fatality rates of 90 to 100%. It is unclear whether these EEG patterns represent a condition to be treated with anticonvulsants to improve outcome, or an expression of severe ischemic damage, in which treatment is futile.

Methods/Design

TELSTAR is a multicenter clinical trial with two parallel groups, randomized treatment allocation, open label treatment, and blinded endpoint evaluation (PROBE design). We aim to enroll 172 adult patients with postanoxic encephalopathy and electroencephalographic status epilepticus after successful cardiopulmonary resuscitation, admitted to the ICU, in whom continuous EEG monitoring is started within 24 hours after admission. Patients are randomly assigned to either medical treatment to suppress all electrographic seizure activity, or no treatment of electroencephalographic status epilepticus. Antiepileptic treatment is based on guidelines for treatment of overt status epilepticus and is started within 3 hours after the diagnosis. If status epilepticus returns during tapering of sedative medication after suppression of all epileptiform activity for 2 × 24 hours, it will be considered refractory. The primary outcome measure is neurological outcome defined as the Cerebral Performance Category (CPC) score at 3 months, dichotomized into ‘good’ (CPC 1 to 2 = no or moderate neurological disability) and ‘poor’ (CPC 3 to 5 = severe disability, coma, or death). Secondary outcome measures include mortality and, for patients surviving up to 12 months, cognitive functioning, health related quality of life, and depression.

Trial registration

Clinicaltrials.gov; NCT02056236. Date of registration: 4 February 2014.

The standardization debate: A conflation trap in critical care electroencephalography

PURPOSE

Persistent uncertainty over the clinical significance of various pathological continuous electroencephalography (cEEG) findings in the intensive care unit (ICU) has prompted efforts to standardize ICU cEEG terminology and an ensuing debate. We set out to understand the reasons for, and a satisfactory resolution to, this debate.

METHOD

We review the positions for and against standardization, and examine their deeper philosophical basis.

RESULTS

We find that the positions for and against standardization are not fundamentally irreconcilable. Rather, both positions stem from conflating the three cardinal steps in the classic approach to EEG, which we term "description", "interpretation", and "prescription". Using real-world examples we show how this conflation yields muddled clinical reasoning and unproductive debate among electroencephalographers that is translated into confusion among treating clinicians. We propose a middle way that judiciously uses both standardized terminology and clinical reasoning to disentangle these critical steps and apply them in proper sequence.

CONCLUSION

The systematic approach to ICU cEEG findings presented herein not only resolves the standardization debate but also clarifies clinical reasoning by helping electroencephalographers assign appropriate weights to cEEG findings in the face of uncertainty.

Serum neuron specific enolase - impact of storage and measuring method

Background

Neuron specific enolase (NSE) is a recognized biomarker for assessment of neurological outcome after cardiac arrest, but its reliability has been questioned. Our aim was to investigate what influence storage of samples and choice of measuring methods may have on levels of NSE in peripheral blood.

Methods

Two serum samples were drawn simultaneously from 51 hypothermia treated cardiac arrest patients. One sample (original sample) was analysed when collected, using the Diasorin-method (LIAISON®NSE, LNSE). The other sample was frozen, stored at −70°C (stored sample), and reanalysed in the same laboratory 4–7 years later using both the Diasorin method and a Roche-method (NSE Cobas e601, CNSE). In addition, a comparison of the two methods was performed on 29 fresh samples.

Results

The paired NSE results in original and stored samples were not significantly different, using the LNSE-method. The two methods produced significantly different results (p < 0.0001) on the paired, stored samples, with the CNSE method yielding higher values than the LNSE-method in 96% of samples. The CNSE method resulted in 36% higher values on average. In the method comparison on fresh samples, the CNSE-method generated on average 15% higher values compared to the LNSE-method, and the difference between the paired results was significant (p < 0.0001).

Conclusion

The CNSE method generated consistently higher NSE-values than the LNSE method and this difference was more pronounced when frozen samples were analysed. Tolerability for prolonged freezing was acceptable.

Electroencephalography (EEG) for neurological prognostication after cardiac arrest and targeted temperature management; rationale and study design

BACKGROUND

Electroencephalography (EEG) is widely used to assess neurological prognosis in patients who are comatose after cardiac arrest, but its value is limited by varying definitions of pathological patterns and by inter-rater variability. The American Clinical Neurophysiology Society (ACNS) has recently proposed a standardized EEG-terminology for critical care to address these limitations.

METHODS/DESIGN

In the TTM-trial, 399 post cardiac arrest patients who remained comatose after rewarming underwent a routine EEG. The presence of clinical seizures, use of sedatives and antiepileptic drugs during the EEG-registration were prospectively documented.

DISCUSSION

A well-defined terminology for interpreting post cardiac arrest EEGs is critical for the use of EEG as a prognostic tool.

TRIAL REGISTRATION

The TTM-trial is registered at ClinicalTrials.gov (NCT01020916).

An update in postcardiac arrest management and prognosis in the era of therapeutic hypothermia

Prognostication of patients who remain comatose following successful resuscitation after cardiac arrest has long posed a challenge for the consulting neurologist. With increasing rates of early defibrillation, out-of-hospital cardiopulmonary resuscitation, and expanding use of therapeutic hypothermia, prognostication in hypoxic-ischemic encephalopathy has become an increasingly common consult for neurologists. Much of the data we previously relied upon for prognostication were taken from patients who were not treated with therapeutic hypothermia. In this review, we examine useful prognostic tools and markers, including the physical examination, evaluation of myoclonus, electroencephalogram monitoring, somatosensory-evoked potentials, biochemical markers of neuronal injury, and neuroimaging. Neurologists must avoid overly pessimistic prognostic statements regarding survival, awakening from coma, or future quality of life, as such statements may unduly influence decisions regarding the continuation of life-sustaining treatment. Conversely, continuation of aggressive medical management in a patient without any hope of awakening should also be avoided. Thus, an understanding of the utility and the limitations of these prognostic tools in the era of therapeutic hypothermia is essential.

Refractory and super-refractory status epilepticus--an update

Status epilepticus is a medical emergency with a high mortality. Early recognition and initiation of treatment leads to a better response and may improve outcomes. Refractory status epilepticus is defined as recurrent seizure activity despite two appropriately selected and dosed antiepileptic drugs including a benzodiazepine. The term "super-refractory status epilepticus" was introduced during the London-Innsbruck Colloquium on status epilepticus in 2011 and refers to status epilepticus that continues or recurs 24 h or more after the initiation of treatment with anesthetic antiepileptic drugs. This includes cases in which seizure control is attained after induction of anesthesia but recurs on weaning the patient off the anesthetic agent. This article reviews the approach to refractory status epilepticus and super-refractory status epilepticus, including management as well as common pathophysiological causes of these entities.

EEG patterns in hypoxic encephalopathies (post-cardiac arrest syndrome): fluctuations, transitions, and reactions

In patients with coma resulting from hypoxic encephalopathy (e.g., after cardiac arrest), the EEG may reflect the severity of brain dysfunction, although the exact relationship among the EEG changes, the extent of neuronal damage, and consequent prognosis is still under study. Many prognostications are based on particular EEG patterns at a time point, such as burst suppression or generalized periodic discharges, but with sequential, repeated, or with prolonged or continuous EEG monitoring, it has become increasingly clear that more information might be gleaned from EEG pattern changes over time. Short-term fluctuations (as opposed to permanent transitions), or preserved reactions to exogenous stimuli, have to be differentiated. This review presents many of the typical postanoxic EEG patterns, along with their evolution over time. This preliminary report illustrates the temporal dynamic changes of EEG over time. It is hoped that it will act as a starting point for prospective and systematic investigation to test whether EEG evolution and transitions add diagnostic and prognostic value.

Clinical and electroencephalographic correlates of acute encephalopathy

The term encephalopathy encompasses a wide variety of syndromes caused by a large number of different toxic, metabolic, and degenerative derangements. Despite advances in intensive medical care and new diagnostic procedures, encephalopathy remains a frequent and underrecognized critical medical condition with high morbidity and mortality. Electroencephalography (EEG) enables rapid bedside electrophysiological measurements of brain dysfunction and complements clinical and neuroimaging assessment of encephalopathic patients. Both progressive slowing of EEG background activity with increasing cerebral compromise and decreased EEG reactivity to external stimuli provide important diagnostic and prognostic information. The aim of this review was to provide an overview of the diagnostic and prognostic value of EEG in encephalopathic patients.

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.

Unstandardized treatment of electroencephalographic status epilepticus does not improve outcome of comatose patients after cardiac arrest

Objective: Electroencephalographic status epilepticus occurs in 9–35% of comatose patients after cardiac arrest. Mortality is 90–100%. It is unclear whether (some) seizure patterns represent a condition in which anti-epileptic treatment may improve outcome, or severe ischemic damage, in which treatment is futile. We explored current treatment practice and its effect on patients’ outcome.

Methods: We retrospectively identified patients that were treated with anti-epileptic drugs from our prospective cohort study on the value of continuous electroencephalography (EEG) in comatose patients after cardiac arrest. Outcome at 6 months was dichotomized between “good” [cerebral performance category (CPC) 1 or 2] and “poor” (CPC 3, 4, or 5). EEG analyses were done at 24 h after cardiac arrest and during anti-epileptic treatment. Unequivocal seizures and generalized periodic discharges during more than 30 min were classified as status epilepticus.

Results: Thirty-one (22%) out of 139 patients were treated with anti-epileptic drugs (phenytoin, levetiracetam, valproate, clonazepam, propofol, midazolam), of whom 24 had status epilepticus. Dosages were moderate, barbiturates were not used, medication induced burst-suppression not achieved, and treatment improved electroencephalographic status epilepticus patterns temporarily (<6 h). Twenty-three patients treated for status epilepticus (96%) died. In patients with status epilepticus at 24 h, there was no difference in outcome between those treated with and without anti-epileptic drugs.

Conclusion: In comatose patients after cardiac arrest complicated by electroencephalographic status epilepticus, current practice includes unstandardized, moderate treatment with anti-epileptic drugs. Although widely used, this does probably not improve patients’ outcome. A randomized controlled trial to estimate the effect of standardized, aggressive treatment, directed at complete suppression of epileptiform activity during at least 24 h, is needed and in preparation.

Neuroprognostication of hypoxic-ischaemic coma in the therapeutic hypothermia era

Neurological prognostication after cardiac arrest has always been challenging, and has become even more so since the advent of therapeutic hypothermia (TH) in the early 2000s. Studies in this field are prone to substantial biases--most importantly, the self-fulfilling prophecy of early withdrawal of life-sustaining therapies--and physicians must be aware of these limitations when evaluating individual patients. TH mandates sedation and prolongs drug metabolism, and delayed neuronal recovery is possible after cardiac arrest with or without hypothermia treatment; thus, the clinician must allow an adequate observation period to assess for delayed recovery. Exciting advances have been made in clinical evaluation, electrophysiology, chemical biomarkers and neuroimaging, providing insights into the underlying pathophysiological mechanisms of injury, as well as prognosis. Some clinical features, such as pupillary reactivity, continue to provide robust information about prognosis, and EEG patterns, such as reactivity and continuity, seem promising as prognostic indicators. Evoked potential information is likely to remain a reliable prognostic tool in TH-treated patients, whereas traditional serum biomarkers, such as neuron-specific enolase, may be less reliable. Advanced neuroimaging techniques, particularly those utilizing MRI, hold great promise for the future. Clinicians should continue to use all the available tools to provide accurate prognostic advice to patients after cardiac arrest.

Value analysis of continuous EEG in patients during therapeutic hypothermia after cardiac arrest

INTRODUCTION

Therapeutic hypothermia (TH) is standard of care after ventricular fibrillation cardiac arrest (CA). Continuous EEG monitoring (cEEG) is increasingly used during TH. Analysis regarding value of cEEG utilization in this population in the context of cost and outcome has not been performed. We compared outcome and EEG charges in CA patients with selective versus routine cEEG.

METHODS

A protocol for TH after CA without routine cEEG was implemented in December 2005, comprising our TH-pre-cEEG cohort. In November 2009, this protocol was changed to include cEEG in all CA-TH patients, comprising our TH-cEEG cohort. Clinical outcome using the Cerebral Performance Category (CPC) at discharge and estimated EEG charges were calculated retrospectively for both cohorts, based on National Charge Data 50th percentile charges expressed in USD per the CMS 2010 Standard Analytical File as reported in Code Correct by MedAssets, Inc.

RESULTS

Our TH-pre-cEEG cohort comprised 91 patients, our TH-cEEG cohort 62. In the TH-pre-cEEG cohort, 19 patients (21%) had rEEGs, 4 (4%) underwent cEEG. The mean estimated EEG charges for the TH-pre-cEEG cohort was $1571.59/patient, and TH-cEEG cohort was $4214.93/patient (p<0.0001). Two patients (2.1%) in the TH-pre-cEEG cohort had seizures, compared to five (8.1%) in the TH-cEEG cohort (p=0.088). There was no difference in mortality or clinical outcome in these cohorts.

CONCLUSIONS

Routine use of cEEG during TH after CA improved seizure detection, but not outcomes. There was a three-fold increase in EEG estimated charges with routine use of cEEG.