Predictors of awakening from postanoxic status epilepticus after therapeutic hypothermia

How to assess prognosis after cardiac arrest and therapeutic hypothermia

The prognosis of patients who are admitted in a comatose state following successful resuscitation after cardiac arrest remains uncertain. Although the introduction of therapeutic hypothermia (TH) and improvements in post-resuscitation care have significantly increased the number of patients who are discharged home with minimal brain damage, short-term assessment of neurological outcome remains a challenge. The need for early and accurate prognostic predictors is crucial, especially since sedation and TH may alter the neurological examination and delay the recovery of motor response for several days. The development of additional tools, including electrophysiological examinations (electroencephalography and somatosensory evoked potentials), neuroimaging and chemical biomarkers, may help to evaluate the extent of brain injury in these patients. Given the extensive literature existing on this topic and the confounding effects of TH on the strength of these tools in outcome prognostication after cardiac arrest, the aim of this narrative review is to provide a practical approach to post-anoxic brain injury when TH is used. We also discuss when and how these tools could be combined with the neurological examination in a multimodal approach to improve outcome prediction in this population.

Continuous Electroencephalogram in Comatose Postcardiac Arrest Syndrome Patients Treated With Therapeutic Hypothermia

Purpose:

Therapeutic Hypothermia (TH) is the only therapeutic intervention proven to significantly improve survival and neurologic outcome in comatose postcardiac arrest patients and is now considered standard of care. When we discuss prognostication with regard to comatose survivors postcardiac arrest, we should look for tools that are both reliable and accurate and that achieve a false-positive rate (FPR) equal to or very closely approaching zero.

Methods:

We retrospectively reviewed data that were prospectively collected on all cardiac arrest patients admitted to our ICU. Continuous electroencephalogram (cEEG) monitoring was performed as part of our protocol for therapeutic hypothermia in comatose postcardiac arrest patients. The primary outcome measure was the best score on hospital discharge on the 5-point Glasgow-Pittsburgh cerebral performance category (CPC) scores.

Results:

A total of 58 patients were included in this study. Twenty five (43%) patients had a good neurologic outcome (CPC score of 1-2). Three (5.2%) patients had nonconvulsive status epilepticus, all of whom had poor outcome (CPC = 5). Seventeen (29%) patients had burst suppression (BS); all had poor outcome. Both nonconvuslsive seizures (NCS) and BS had a specificity of 100% (95% confidence interval [CI], 84%-100%), positive predictive values of 100% (95% CI, 31%-100%), and 100% (95% CI, 77%-100%), respectively. Both NCS and BS had FPRs of zero (95% CI, 0.0-0.69, and 0.0-0.23, respectively).

Conclusions:

In comatose postcardiac arrest patients treated with hypothermia, EEG during the maintenance and rewarming phase of hypothermia can contribute to prediction of neurologic outcome. Pending large multicenter prospective studies evaluating the role of cEEG in prognostication, our study adds to the existing evidence that cEEG can play a potential role in prediction of outcome in postcardiac arrest patients treated with hypothermia.

Automated analysis of background EEG and reactivity during therapeutic hypothermia in comatose patients after cardiac arrest

Visual analysis of electroencephalography (EEG) background and reactivity during therapeutic hypothermia provides important outcome information, but is time-consuming and not always consistent between reviewers. Automated EEG analysis may help quantify the brain damage. Forty-six comatose patients in therapeutic hypothermia, after cardiac arrest, were included in the study. EEG background was quantified with burst-suppression ratio (BSR) and approximate entropy, both used to monitor anesthesia. Reactivity was detected through change in the power spectrum of signal before and after stimulation. Automatic results obtained almost perfect agreement (discontinuity) to substantial agreement (background reactivity) with a visual score from EEG-certified neurologists. Burst-suppression ratio was more suited to distinguish continuous EEG background from burst-suppression than approximate entropy in this specific population. Automatic EEG background and reactivity measures were significantly related to good and poor outcome. We conclude that quantitative EEG measurements can provide promising information regarding current state of the patient and clinical outcome, but further work is needed before routine application in a clinical setting.

Managing the Complications of Mild Therapeutic Hypothermia in the Cardiac Arrest Patient

Mild therapeutic hypothermia (MTH) is used to lower the core body temperature of cardiac arrest (CA) patients to 32°C from 34°C to provide improved survival and neurologic outcomes after resuscitation from in-hospital or out-of-hospital CA. Despite the improved benefits of MTH, there are potentially unforeseen complications associated during management. Although the adverse effects are transient, the clinician should be aware of the associated complications when managing the patient receiving MTH. We aim to provide the medical community comprehensive information related to the potential complications of survivors of CA receiving MTH, as it is imperative for the clinician to understand the physiologic changes that take place in the patient receiving MTH and how to prepare for them and manage them if they do occur. We hope to provide information of how to manage these potential complications through both a review of the current literature and a reflection of our own experience.

Good functional outcome after prolonged postanoxic comatose myoclonic status epilepticus in a patient who had undergone bone marrow transplantation

In anoxic coma, myoclonic status epilepticus and other nonreactive epileptiform patterns are considered as signs of poor prognosis. We report the case of a good recovery in a prolonged comatose myoclonic status epilepticus (MSE) after a cardiac arrest (CA) treated with mild therapeutic hypothermia (TH) in a patient who had undergone a bone marrow transplantation for Hodgkin's lymphoma. This case emphasizes the opportunity of performing an electroencephalogram (EEG) in the acute period after an hypoxic-ischemic insult and underlines the diagnostic difficulties between MSE and Lance-Adams syndrome, which classically occurs after the patient has regained consciousness, but can also begin while the patient is still comatose or sedated. Major problems in prognostication for postarrest comatose patients will also be pointed out.

Predictors of Outcome Post Cardiac Arrest

Early predictors of prognosis in comatose patients post cardiac arrest help inform decisions surrounding continuation or withdrawal of treatment and provide a framework on which to better inform relatives of the likely outcome. Markers defined prior to the widespread use of therapeutic hypothermia post arrest may no longer be reliable and an up-to-date analysis of the literature is presented.

Clinical examination for prognostication in comatose cardiac arrest patients

OBJECTIVE

To build new algorithms for prognostication of comatose cardiac arrest patients using clinical examination, and investigate whether therapeutic hypothermia influences the value of the clinical examination.

METHODS

From 2000 to 2007, 500 consecutive patients in non-traumatic coma were prospectively enrolled, 200 of whom were post-cardiac arrest. Outcome was determined by modified Rankin Scale (mRS) score at 6 months, with mRS≤3 indicating good outcome. The clinical examination was performed on days 0, 1, 3 and 7 post-arrest, and clinical variables analyzed for importance in prognostication of outcome. A classification and regression tree analysis (CART) was used to develop a predictive algorithm.

RESULTS

Good outcome was achieved in 9.9% of patients. In CART analysis, motor response was often chosen as a root node, and spontaneous eye movements, pupillary reflexes, eye opening and corneal reflexes were often chosen as splitting nodes. Over 8% of patients with absent or extensor motor response on day 3 achieved a good outcome, as did 2 patients with myoclonic status epilepticus. The odds of achieving a good outcome were lower in patients who suffered asystole (OR 0.187, 95% CI: 0.039-0.875, p=0.033) compared with ventricular fibrillation or non-perfusing ventricular tachycardia, but some still achieved good outcome. The absence of pupillary and corneal reflexes on day 3 remained highly reliable for predicting poor outcome, regardless of therapeutic hypothermia utilization.

CONCLUSION

The clinical examination remains central to prognostication in comatose cardiac arrest patients in the modern area. Future studies should incorporate the clinical examination along with modern technology for accurate prognostication.

Feasibility and cardiac safety of inhaled xenon in combination with therapeutic hypothermia following out-of-hospital cardiac arrest

OBJECTIVES

Preclinical studies reveal the neuroprotective properties of xenon, especially when combined with hypothermia. The purpose of this study was to investigate the feasibility and cardiac safety of inhaled xenon treatment combined with therapeutic hypothermia in out-of-hospital cardiac arrest patients.

DESIGN

An open controlled and randomized single-centre clinical drug trial (clinicaltrials.gov NCT00879892).

SETTING

A multipurpose ICU in university hospital.

PATIENTS

Thirty-six adult out-of-hospital cardiac arrest patients (18-80 years old) with ventricular fibrillation or pulseless ventricular tachycardia as initial cardiac rhythm.

INTERVENTIONS

Patients were randomly assigned to receive either mild therapeutic hypothermia treatment with target temperature of 33°C (mild therapeutic hypothermia group, n=18) alone or in combination with xenon by inhalation, to achieve a target concentration of at least 40% (Xenon+mild therapeutic hypothermia group, n=18) for 24 hours. Thirty-three patients were evaluable (mild therapeutic hypothermia group, n=17; Xenon+mild therapeutic hypothermia group, n=16).

MEASUREMENTS AND MAIN RESULTS

Patients were treated and monitored according to the Utstein protocol. The release of troponin-T was determined at arrival to hospital and at 24, 48, and 72 hours after out-of-hospital cardiac arrest. The median end-tidal xenon concentration was 47% and duration of the xenon inhalation was 25.5 hours. The frequency of serious adverse events, including inhospital mortality, status epilepticus, and acute kidney injury, was similar in both groups and there were no unexpected serious adverse reactions to xenon during hospital stay. In addition, xenon did not induce significant conduction, repolarization, or rhythm abnormalities. Median dose of norepinephrine during hypothermia was lower in xenon-treated patients (mild therapeutic hypothermia group=5.30 mg vs Xenon+mild therapeutic hypothermia group=2.95 mg, p=0.06). Heart rate was significantly lower in Xenon+mild therapeutic hypothermia patients during hypothermia (p=0.04). Postarrival incremental change in troponin-T at 72 hours was significantly less in the Xenon+mild therapeutic hypothermia group (p=0.04).

CONCLUSIONS

Xenon treatment in combination with hypothermia is feasible and has favorable cardiac features in survivors of out-of-hospital cardiac arrest.

A review of long-term EEG monitoring in critically ill children with hypoxic-ischemic encephalopathy, congenital heart disease, ECMO, and stroke

Continuous EEG monitoring is being used with increasing frequency in critically ill children with hypoxic ischemic encephalopathy, congenital heart disease, stroke, and extracorporeal membrane oxygenation (ECMO). The primary indication for EEG monitoring is to identify electrographic seizures and electrographic status epilepticus, which have been associated with worse outcome in some populations. A secondary indication is to provide prognostic information. This review summarizes the available data regarding continuous EEG monitoring in critically ill children with special attention to hypoxic ischemic encephalopathy, congenital heart disease, stroke, and children undergoing ECMO.

Yield of intermittent versus continuous EEG in comatose survivors of cardiac arrest treated with hypothermia

Introduction

Electroencephalography (EEG) has a central role in the outcome prognostication in subjects with anoxic/hypoxic encephalopathy following a cardiac arrest (CA). Continuous EEG monitoring (cEEG) has been consistently developed and studied; however, its yield as compared to repeated standard EEG (sEEG) is unknown.

Methods

We studied a prospective cohort of comatose adults treated with therapeutic hypothermia (TH) after a CA. cEEG data regarding background activity and epileptiform components were compared to two 20-minute sEEGs extracted from the cEEG recording (one during TH, and one in early normothermia).

Results

Thirty-four recordings were studied. During TH, the agreement between cEEG and sEEG was 97.1% (95% CI: 84.6 to 99.9%) for background discontinuity and reactivity evaluation, while it was 94.1% (95% CI 80.3 to 99.2%) regarding epileptiform activity. In early normothermia, we did not find any discrepancies. Thus, concordance results were very good during TH (kappa 0.83), and optimal during normothermia (kappa = 1). The median delay between CA and the first EEG reactivity testing was 18 hours (range: 4.75 to 25) for patients with perfect agreement and 10 hours (range: 5.75 to 10.5) for the three patients with discordant findings (P = 0.02, Wilcoxon).

Conclusions

Standard intermittent EEG has comparable performance with continuous EEG both for variables important for outcome prognostication (EEG reactivity) and identification of epileptiform transients in this relatively small sample of comatose survivors of CA. This finding has an important practical implication, especially for centers where EEG resources are limited.

Status epilepticus: current treatment strategies

Status epilepticus is a neurological emergency that is commonly encountered by the neurohospitalist. Successful treatment depends upon the recognition of prolonged seizure activity and the acute mobilization of available resources. Pharmacologic treatment regimens have been shown to decrease the time needed for successful control of seizures and have provided for the rapid administration of anticonvulsant medications. Treatment strategies have evolved so that clinicians can administer effective doses of medication by whatever routes of administration are immediately available. Traditional algorithms for the treatment of status epilepticus have used a stepwise approach to the administration of first-, second-, and third-order medications. More recent options have included aggressive anesthetic doses of medications while second-line medications are being titrated.

Clinical review: Continuous and simplified electroencephalography to monitor brain recovery after cardiac arrest

There has been a dramatic change in hospital care of cardiac arrest survivors in recent years, including the use of target temperature management (hypothermia). Clinical signs of recovery or deterioration, which previously could be observed, are now concealed by sedation, analgesia, and muscle paralysis. Seizures are common after cardiac arrest, but few centers can offer high-quality electroencephalography (EEG) monitoring around the clock. This is due primarily to its complexity and lack of resources but also to uncertainty regarding the clinical value of monitoring EEG and of treating post-ischemic electrographic seizures. Thanks to technical advances in recent years, EEG monitoring has become more available. Large amounts of EEG data can be linked within a hospital or between neighboring hospitals for expert opinion. Continuous EEG (cEEG) monitoring provides dynamic information and can be used to assess the evolution of EEG patterns and to detect seizures. cEEG can be made more simple by reducing the number of electrodes and by adding trend analysis to the original EEG curves. In our version of simplified cEEG, we combine a reduced montage, displaying two channels of the original EEG, with amplitude-integrated EEG trend curves (aEEG). This is a convenient method to monitor cerebral function in comatose patients after cardiac arrest but has yet to be validated against the gold standard, a multichannel cEEG. We recently proposed a simplified system for interpreting EEG rhythms after cardiac arrest, defining four major EEG patterns. In this topical review, we will discuss cEEG to monitor brain function after cardiac arrest in general and how a simplified cEEG, with a reduced number of electrodes and trend analysis, may facilitate and improve care.

A structured approach to neurologic prognostication in clinical cardiac arrest trials

Brain injury is the dominant cause of death for cardiac arrest patients who are admitted to an intensive care unit, and the majority of patients die after withdrawal of life sustaining therapy (WLST) based on a presumed poor neurologic outcome. Mild induced hypothermia was found to decrease the reliability of several methods for neurological prognostication. Algorithms for prediction of outcome, that were developed before the introduction of mild hypothermia after cardiac arrest, may have affected the results of studies with hypothermia-treated patients. In previous trials on neuroprotection after cardiac arrest, including the pivotal hypothermia trials, the methods for prognostication and the reasons for WLST were not reported and may have had an effect on outcome. In the Target Temperature Management trial, in which 950 cardiac arrest patients have been randomized to treatment at 33°C or 36°C, neuroprognostication and WLST-decisions are strictly protocolized and registered. Prognostication is delayed to at least 72 hours after the end of the intervention period, thus a minimum of 4.5 days after the cardiac arrest, and is based on multiple parameters to account for the possible effects of hypothermia.

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.

Prognosis in severe brain injury

BACKGROUND

The prediction of neurologic outcome is a fundamental concern in the resuscitation of patients with severe brain injury.

OBJECTIVE

To provide an evidence-based update on neurologic prognosis following traumatic brain injury and hypoxic-ischemic encephalopathy after cardiac arrest.

DATA SOURCE

Search of the PubMed database and manual review of bibliographies from selected articles to identify original data relating to prognostic methods and outcome prediction models in patients with neurologic trauma or hypoxic-ischemic encephalopathy.

DATA SYNTHESIS AND CONCLUSION

Articles were scrutinized regarding study design, population evaluated, interventions, outcomes, and limitations. Outcome prediction in severe brain injury is reliant on features of the neurologic examination, anatomical and physiological changes identified with CT and MRI, abnormalities detected with electroencephalography and evoked potentials, and physiological and biochemical derangements at both the brain and systemic levels. Use of such information in univariable association studies generally lacks specificity in classifying neurologic outcome. Furthermore, the accuracy of established prognostic classifiers may be affected by the introduction of outcome-modifying interventions, such as therapeutic hypothermia following cardiac arrest. Although greater specificity may be achieved with scoring systems derived from multivariable models, they generally fail to predict outcome with sufficient accuracy to be meaningful at the single patient level. Discriminative models which integrate knowledge of genetic determinants and biologic processes governing both injury and repair and account for the effects of resuscitative and rehabilitative care are needed.

Brain resuscitation in the drowning victim

Drowning is a leading cause of accidental death. Survivors may sustain severe neurologic morbidity. There is negligible research specific to brain injury in drowning making current clinical management non-specific to this disorder. This review represents an evidence-based consensus effort to provide recommendations for management and investigation of the drowning victim. Epidemiology, brain-oriented prehospital and intensive care, therapeutic hypothermia, neuroimaging/monitoring, biomarkers, and neuroresuscitative pharmacology are addressed. When cardiac arrest is present, chest compressions with rescue breathing are recommended due to the asphyxial insult. In the comatose patient with restoration of spontaneous circulation, hypoxemia and hyperoxemia should be avoided, hyperthermia treated, and induced hypothermia (32-34 °C) considered. Arterial hypotension/hypertension should be recognized and treated. Prevent hypoglycemia and treat hyperglycemia. Treat clinical seizures and consider treating non-convulsive status epilepticus. Serial neurologic examinations should be provided. Brain imaging and serial biomarker measurement may aid prognostication. Continuous electroencephalography and N20 somatosensory evoked potential monitoring may be considered. Serial biomarker measurement (e.g., neuron specific enolase) may aid prognostication. There is insufficient evidence to recommend use of any specific brain-oriented neuroresuscitative pharmacologic therapy other than that required to restore and maintain normal physiology. Following initial stabilization, victims should be transferred to centers with expertise in age-specific post-resuscitation neurocritical care. Care should be documented, reviewed, and quality improvement assessment performed. Preclinical research should focus on models of asphyxial cardiac arrest. Clinical research should focus on improved cardiopulmonary resuscitation, re-oxygenation/reperfusion strategies, therapeutic hypothermia, neuroprotection, neurorehabilitation, and consideration of drowning in advances made in treatment of other central nervous system disorders.

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.

Postanoxic status epilepticus can be identified and treatment guided successfully by continuous electroencephalography

Prognostication after cardiac arrest and therapeutic hypothermia is challenging. Recent data indicate that a subgroup of patients with postanoxic status epilepticus may recover. We describe a case of postanoxic status epilepticus with good outcome where a multimodal prognostic strategy motivated active and prolonged treatment. Our patient was a 61-year-old woman resuscitated from out-of-hospital cardiac arrest, treated with hypothermia, and monitored with continuous electroencephalography (EEG). Shortly after rewarming, 44 hours after cardiac arrest, electrographic status epilepticus developed and was manifested clinically by myoclonic seizures several hours later. Treatment was guided by continuous simplified EEG monitoring. Conventional antiepileptics were ineffective, and prolonged sedation was necessary to prevent recurrence. Magnetic resonance imaging, somatosensory evoked potentials, and repeated measurements of neuron-specific enolase were unremarkable and did not indicate a poor prognosis. Rather, the EEG characteristics suggested a potential for recovery, and therefore the patient was actively treated until recovery 3 weeks later. At follow-up after 4.5 months, she had only minor neurological sequels. We conclude that a favorable neurological outcome is possible despite prolonged postanoxic status epilepticus. A multimodal strategy for prognostication may help identify treatable cases. Continuous EEG monitoring is an important tool to detect and guide treatment of postanoxic status epilepticus.

The prognostic value of gray-white-matter ratio in cardiac arrest patients treated with hypothermia

Background

Mild therapeutic hypothermia alters the validity of a number of parameters currently used to predict neurological outcome after cardiac arrest and resuscitation. Thus, additional parameters are needed to increase certainty of early prognosis in these patients. A promising new approach is the determination of the gray-white-matter ratio (GWR) in cranial computed tomography (CCT) obtained early after resuscitation. It is not known how GWR relates to established outcome parameters such as neuron specific enolase (NSE) or somatosensory evoked potentials (SSEP).

Methods

Cardiac arrest patients (n = 98) treated with hypothermia were retrospectively analyzed with respect to the prognostic value of GWR, NSE and SSEP.

Results

A GWR < 1.16 predicted poor outcome with 100% specificity and 38% sensitivity. In 62 patients NSE, SSEP and CCT were available. The sensitivity of poor outcome prediction by both NSE > 97 μg/L and bilateral absent SSEP was 43%. The sensitivity increased to 53% in a multi-parameter approach predicting poor outcome using at least two of the three parameters (GWR, NSE and SSEP).

Conclusion

Our results suggest a strong association of a low GWR with poor outcome following cardiac arrest. Determination of the GWR increases the sensitivity in a multi-parameter approach for prediction of poor outcome after cardiac arrest.

Assessing prognosis following cardiopulmonary resuscitation and therapeutic hypothermia-a critical discussion of recent studies

BACKGROUND

The prognosis of patients who are comatose after cardiopulmonary resuscitation (CPR) is poor but can be improved by mild therapeutic hypothermia. We studied the question whether the known, reliable indicators of a poor prognosis after CPR are also valid for patients treated with CPR and hypothermia.

METHODS

This review is based on a selective search of the PubMed database for recent articles on the assessment of prognosis in persons who are comatose after CPR and therapeutic hypothermia.

RESULTS

On the basis of 21 clinical trials, 4 of which yielded level I evidence, 9 level II evidence, and 8 level III evidence, the following were identified as reliable indicators of a poor prognosis: generalized myoclonus, bilateral absence of the pupillary light response or of the corneal reflex, bilateral absence of the cortical components of median nerve somatosensory evoked potentials, a burst-suppression or isoelectric EEG, continuous generalized epileptiform discharges, and an elevated serum concentration of neuron-specific enolase (with a higher cutoff value than for normothermic patients).

CONCLUSION

If the prognosis is poor, this should be thoroughly discussed with the patient's family, and the nature and extent of further intensive treatment should be reconsidered. The patient's wishes, if known, are paramount. Any decision to withhold care should be taken only if there are multiple concurrent indicators of a poor prognosis. If only one such indicator is present, or if the findings are inconsistent, such decisions should be postponed.

The neuro-ICU patient and electroencephalography paroxysms: if and when to treat

PURPOSE OF REVIEW

To review recent clinical data and summarize actual recommendations for the management of electrographic seizures and status epilepticus in neuro-ICU patients.

RECENT FINDINGS

Electrographic, 'nonconvulsive', seizures are frequent in neuro-ICU patients including traumatic brain injury, subarachnoid hemorrhage, intracerebral hemorrhage and hypoxic-ischemic encephalopathy. Continuous electroencephalography monitoring is thus of great potential utility. The impact of electrographic seizures on outcome however is not entirely established and it is also unclear what type of electroencephalography paroxysms require treatment and when and how exactly to treat them. Evidence from randomized studies is lacking and will not be available in the near future. Given robust animal and human evidence showing the potential negative impact of seizures on secondary cerebral damage and outcome, treatment of seizures appears reasonable, particularly if related to status epilepticus. On the contrary, over-aggressive antiepileptic therapy entails risks. The management of seizures should therefore be guided individually, based on the underlying cause, the severity of illness and patient comorbidities.

SUMMARY

We provide a pragmatic approach for the management of electrographic seizures in neuro-ICU patients. International consensus guidelines on continuous electroencephalography monitoring and seizure therapy are needed and would represent the rationale for a future multicenter randomized trial.

Continuous evaluation of neurological prognosis after cardiac arrest

Post-resuscitation care has changed in the last decade, and outcome after cardiac arrest has improved, thanks to several combined measures. Induced hypothermia has shown a treatment benefit in two randomized trials, but some doubts remain. General care has improved, including the use of emergency coronary intervention. Assessment of neurological function and prognosis in comatose cardiac arrest patient is challenging, especially when treated with hypothermia. In this review, we evaluate the recent literature and discuss the available evidence for prognostication after cardiac arrest in the era of temperature management. Relevant literature was identified searching PubMed and reading published papers in the field, but no standardized search strategy was used. The complexity of predicting outcome after cardiac arrest and induced hypothermia is recognized in the literature, and no single test can predict a poor prognosis with absolute certainty. A clinical neurological examination is still the gold standard, but the results need careful interpretation because many patients are affected by sedatives and by hypothermia. Common adjuncts include neurophysiology, brain imaging and biomarkers, and a multimodal strategy is generally recommended. Current guidelines for prediction of outcome after cardiac arrest and induced hypothermia are not sufficient. Based on our expert opinion, we suggest a multimodal approach with a continuous evaluation of prognosis based on repeated neurological examinations and electroencephalography. Somatosensory-evoked potential is an established method to help determine a poor outcome and is recommended, whereas biomarkers and magnetic resonance imaging are promising adjuncts. We recommend that a decisive evaluation of prognosis is performed at 72 h after normothermia or later in a patient free of sedative and analgetic drugs.

Electroencephalographic monitoring in comatose survivors of cardiac arrest

Electroencephalography (EEG) monitoring is an important tool in the management of comatose survivors of cardiac arrest. The results serve to predict the neurological outcome, identify postanoxic status epilepticus, and assess the effectiveness of antiepileptic treatments. Continuous EEG monitoring might seem the most attractive option but is costly and requires the continuous availability of an expert to interpret the findings. Alvarez and colleagues compared repeated standard EEG to continuous EEG monitoring in comatose survivors of cardiac arrest. They found close agreement between these two strategies. However, their results do not constitute evidence of similar performance. In comatose survivors of cardiac arrest, repeated standard EEG should be used only when continuous EEG monitoring is unavailable.

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.

Continuous electroencephalography monitoring for early prediction of neurological outcome in postanoxic patients after cardiac arrest: a prospective cohort study

OBJECTIVE

To evaluate the value of continuous electroencephalography in early prognostication in patients treated with hypothermia after cardiac arrest.

DESIGN

Prospective cohort study.

SETTING

Medical intensive care unit.

PATIENTS

Sixty patients admitted to the intensive care unit for therapeutic hypothermia after cardiac arrest.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

In all patients, continuous electroencephalogram and daily somatosensory evoked potentials were recorded during the first 5 days of admission or until intensive care unit discharge. Neurological outcomes were based on each patient's best achieved Cerebral Performance Category score within 6 months. Twenty-seven of 56 patients (48%) achieved good neurological outcome (Cerebral Performance Category score 1-2).At 12 hrs after resuscitation, 43% of the patients with good neurological outcome showed continuous, diffuse slow electroencephalogram rhythms, whereas this was never observed in patients with poor outcome.The sensitivity for predicting poor neurological outcome of low-voltage and isoelectric electroencephalogram patterns 24 hrs after resuscitation was 40% (95% confidence interval 19%-64%) with a 100% specificity (confidence interval 86%-100%), whereas the sensitivity and specificity of absent somatosensory evoked potential responses during the first 24 hrs were 24% (confidence interval 10%-44%) and 100% (confidence interval: 87%-100%), respectively. The negative predictive value for poor outcome of low-voltage and isoelectric electroencephalogram patterns was 68% (confidence interval 50%-81%) compared to 55% (confidence interval 40%-60%) for bilateral somatosensory evoked potential absence, both with a positive predictive value of 100% (confidence interval 63%-100% and 59%-100% respectively). Burst-suppression patterns after 24 hrs were also associated with poor neurological outcome, but not inevitably so.

CONCLUSIONS

In patients treated with hypothermia, electroencephalogram monitoring during the first 24 hrs after resuscitation can contribute to the prediction of both good and poor neurological outcome. Continuous patterns within 12 hrs predicted good outcome. Isoelectric or low-voltage electroencephalograms after 24 hrs predicted poor outcome with a sensitivity almost two times larger than bilateral absent somatosensory evoked potential responses.

Prognostic value of electrographic postanoxic status epilepticus in comatose cardiac-arrest survivors in the therapeutic hypothermia era

BACKGROUND

The independent prognostic significance of postanoxic status epilepticus (PSE) has not been evaluated prospectively since the introduction of therapeutic hypothermia. We studied 1-year functional outcomes and their determinants in comatose survivors of cardiac arrest (CA), with special attention to PSE.

METHODS

106 comatose CA survivors admitted to the intensive care unit in 2005-2010 were included in a prospective observational study. The main outcome measure was a Cerebral Performance Category scale (CPC) of 1 or 2 (favorable outcome) 1 year after CA.

RESULTS

CA occurred out-of-hospital in 89 (84%) patients and was witnessed from onset in 94 (89%). Median times were 6 min (IQR, 0-11) from CA to first-responder arrival and 23 min (14-40) from collapse to return of spontaneous circulation. PSE was diagnosed in 33 (31%) patients at a median of 39 h (4-49) after CA. PSE was refractory in 24 (22%) cases and malignant in 19 (20%). After 1 year, 31 (29.3%) patients had favorable outcomes including 2 (6.44%) with PSE. Factors independently associated with poor outcome (CPC ≥ 3) were PSE (odds ratio [OR], 14.28; 95% confidence interval [95% CI], 2.77-50.0; P=0.001), time to restoration of spontaneous circulation (OR, 1.04/min; 95% CI, 1-1.07; P=0.035), and LOD score on day 1 (OR, 1.28/point; 95% CI, 1.08-1.54; P=0.003).

CONCLUSION

PSE strongly and independently predicts a poor outcome in comatose CA survivors receiving therapeutic hypothermia, but some patients with PSE survive with good functional outcomes. PSE alone is not sufficient to predict failure to awaken after CA in the era of therapeutic hypothermia.

Hippocampal magnetic resonance imaging abnormalities in cardiac arrest are associated with poor outcome

BACKGROUND

The role of neuroimaging in assessing prognosis in comatose cardiac survivors appears promising, but little is known regarding the import of particular spatial patterns. We report a specific spatial imaging abnormality on magnetic resonance imaging (MRI) that portends a poor prognosis: bilateral hippocampal hyperintensities on diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) sequences.

METHODS

Eighty sequential comatose cardiac arrest patients underwent MRI scans. Qualitative and quantitative regional analyses were performed. Patients were categorized as HIPPO(+) (n = 18) or HIPPO(-) (n = 62) based on whether they had bilateral hippocampal hyperintensities. Poor outcome was defined by a modified Rankin Scale (mRS) score ≥4 at 6 months.

RESULTS

Patients with bilateral hippocampal abnormalities had a higher frequency of poor outcome (P = .032). HIPPO(+) patients suffered more severe cerebral injury, with lower whole brain apparent diffusion coefficient values (P = .043) and a greater number of affected regions on DWI (P = .001) and FLAIR (P = .001) than HIPPO(-) patients. The hippocampal approach was 100% specific for a poor prognosis; only 1 patient survived and remained in a vegetative state.

CONCLUSIONS

Bilateral hippocampal hyperintensities on MRI may be a specific imaging finding that is indicative of poor prognosis in patients who suffer global hypoxic-ischemic injury. More research on the prognostic significance of this and similar neuroimaging patterns is indicated.

Use of hypothermia in the intensive care unit

Used for over 3600 years, hypothermia, or targeted temperature management (TTM), remains an ill defined medical therapy. Currently, the strongest evidence for TTM in adults are for out-of-hospital ventricular tachycardia/ventricular fibrillation cardiac arrest, intracerebral pressure control, and normothermia in the neurocritical care population. Even in these disease processes, a number of questions exist. Data on disease specific therapeutic markers, therapeutic depth and duration, and prognostication are limited. Despite ample experimental data, clinical evidence for stroke, refractory status epilepticus, hepatic encephalopathy, and intensive care unit is only at the safety and proof-of-concept stage. This review explores the deleterious nature of fever, the theoretical role of TTM in the critically ill, and summarizes the clinical evidence for TTM in adults.

Lance-Adams syndrome: Difficulties surrounding diagnosis, prognostication, and treatment after cardiac arrest

It is difficult to predict the neurological outcome in survivor of cardio respiratory arrest. We report a case of 32 year old survivor of respiratory arrest who developed myoclonic jerks following overdose of sedation during spinal anesthesia. We initially thought these to be myoclonic status epilepticus (MSE). Accurate distinction between MSE and Lance-Adams syndrome (LAS) is very important as both have very different prognosis. LAS is a common occurrence in cardiac arrest survivors where the cause is respiratory arrest. Less than 150 cases have been reported in the medical literature till date. Making an early diagnosis and properly managing LAS is positively related to improving the patient's functional outcome. The aim of this manuscript is to spread awareness and knowledge of LAS among ICU doctors. The diagnosis of LAS and the controversies and difficulties that surround its diagnosis and treatment and other aspects of prognostication in cardiac arrest are reviewed.

A case of inaccurate prognostication after the ARCTIC protocol

Therapeutic hypothermia (ARCTIC, or Advanced Resuscitation Cooling Therapeutics and Intensive Care protocol) is a widely recommended intervention to improve mortality and neurologic outcomes after cardiac arrest. However, neurologic outcomes are difficult to predict soon after cardiac arrest in the setting of hypothermia, as illustrated by this case report. A 60-year-old man had witnessed cardiac arrest at home. He was defibrillated twice, with return of spontaneous circulation, and cooled to 33°C for 24 hours. Neurologic exam on Day 6 revealed limited brainstem reflexes, and the intensive care unit team discussed with the patient's family that his prognosis for neurologic recovery was poor. Palliative care was consulted to participate in a goals-of-care meeting. Just prior to the meeting on Day 7, the patient awoke. He fully recovered and walked out of the hospital on Day 18. Prior to induced hypothermia, indicators of poor outcome included lack of one or more brainstem reflexes (pupillary or corneal reflex), absence of motor response at 72 hours, myoclonus, status epilepticus, electroencephalogram with generalized suppression, and absent bilateral cortical N20 response to somatosensory-evoked potentials. However, several studies have found these indicators to be unreliable after hypothermia. This may be the result of sedatives, which can affect physical examination and electroencephalogram results, and delayed clearance. Because of the unreliability of prognostication tests within the first 72 hours of hypothermic protocols in the setting of sedation, it appears prudent in some cases to delay final prognosis discussions until at least six days postcardiac arrest and after neurologic evaluation is done with patients sedative-free.