Electroencephalographic Patterns in Neurocritical Care: Pathologic Contributors or Epiphenomena?

The State of the Field of Pediatric Multimodality Neuromonitoring

BACKGROUND

The use of multimodal neuromonitoring in pediatrics is in its infancy relative to adult neurocritical care. Multimodal neuromonitoring encompasses the amalgamation of information from multiple individual neuromonitoring devices to gain a more comprehensive understanding of the condition of the brain. It allows for adaptation to the changing state of the brain throughout various stages of injury with potential to individualize and optimize therapies.

METHODS

Here we provide an overview of multimodal neuromonitoring in pediatric neurocritical care and its potential application in the future.

RESULTS

Multimodal neuromonitoring devices are key to the process of multimodal neuromonitoring, allowing for visualization of data trends over time and ideally improving the ability of clinicians to identify patterns and find meaning in the immense volume of data now encountered in the care of critically ill patients at the bedside. Clinical use in pediatrics requires more study to determine best practices and impact on patient outcomes. Potential uses include guidance for targets of physiological parameters in the setting of acute brain injury, neuroprotection for patients at high risk for brain injury, and neuroprognostication. Implementing multimodal neuromonitoring in pediatric patients involves interprofessional collaboration with the development of a simultaneous comprehensive program to support the use of multimodal neuromonitoring while maintaining the fundamental principles of the delivery of neurocritical care at the bedside.

CONCLUSIONS

The possible benefits of multimodal neuromonitoring are immense and have great potential to advance the field of pediatric neurocritical care and the health of critically ill children.

Clinical approaches for poststroke seizure: a review

Poststroke seizure is a potential complication of stroke, which is the most frequent acute symptomatic seizure in adults. Patients with stroke may present with an abnormal or aggressive behavior accompanied by altered mental status and symptoms, such as hemiparesis, dysarthria, and sensory deficits. Although stroke manifestations that mimic seizures are rare, diagnosing poststroke seizures can be challenging when accompanied with negative postictal symptoms. Differential diagnoses of poststroke seizures include movement disorders, syncope, and functional (nonepileptic) seizures, which may present with symptoms similar to seizures. Furthermore, it is important to determine whether poststroke seizures occur early or late. Seizures occurring within and after 7 d of stroke onset were classified as early and late seizures, respectively. Early seizures have the same clinical course as acute symptomatic seizures; they rarely recur or require long-term antiseizure medication. Conversely, late seizures are associated with a risk of recurrence similar to that of unprovoked seizures in a patient with a focal lesion, thereby requiring long-term administration of antiseizure medication. After diagnosis, concerns regarding treatment strategies, treatment duration, and administration of primary and secondary prophylaxis often arise. Antiseizure medication decisions for the initiation of short-term primary and long-term secondary seizure prophylaxis should be considered for patients with stroke. Antiseizure drugs such as lamotrigine, carbamazepine, lacosamide, levetiracetam, phenytoin, and valproate may be administered. Poststroke seizures should be diagnosed systematically through history with differential diagnosis; in addition, classifying them as early or late seizures can help to determine treatment strategies.

Multimodal neuromonitoring in the pediatric intensive care unit

Neuromonitoring is used to assess the central nervous system in the intensive care unit. The purpose of neuromonitoring is to detect neurologic deterioration and intervene to prevent irreversible nervous system dysfunction. Neuromonitoring starts with the standard neurologic examination, which may lag behind the pathophysiologic changes. Additional modalities including continuous electroencephalography (CEEG), multiple physiologic parameters, and structural neuroimaging may detect changes earlier. Multimodal neuromonitoring now refers to an integrated combination and display of non-invasive and invasive modalities, permitting tailored treatment for the individual patient. This chapter reviews the non-invasive and invasive modalities used in pediatric neurocritical care.

Association of Cerebral and Systemic Physiology With Quantitative Electroencephalographic Characteristics of Early Posttraumatic Seizures

PURPOSE

Early posttraumatic seizures (EPTS) occur after pediatric traumatic brain injury and have been associated with unfavorable outcomes. We aimed to characterize the relationship among quantitative EEG characteristics of early posttraumatic seizures, cerebral and somatic physiologic measures.

METHODS

Differences in baseline physiologic, neuroimaging, and demographic characteristics between those with and without early posttraumatic seizures were investigated using Mann-Whitney U test or Fisher exact test. Multivariable dynamic structural equations modeling was used to investigate time series associations between ictal quantitative EEG characteristics with intracranial pressure, arterial blood pressure, heart rate (HR), and cerebral regional oximetry. Quantitative EEG characteristics included amplitude, total power, spectral edge frequency, peak value frequency, complexity, and periodicity.

RESULTS

Among 72 children, 146 seizures were identified from 19 patients. Early posttraumatic seizures were associated with younger age ( P = 0.0034), increased HR ( P = 0.0018), and increased Glasgow Outcome Scale-Extended scores ( P = 0.0377). Group dynamic structural equations modeling analysis of the first seizure for patients demonstrated that intracranial pressure is negatively associated with spectral edge frequency (standardized regression coefficient -0.12, 99% credible interval [-0.21 to -0.04]), and HR is positively associated with peak value frequency (standardized regression coefficient 0.16, [0.00-0.31]). Among nine patients with seizures arising over the frontal lobe regions, HR was positively associated with peak value frequency (standardized regression coefficient 0.26 [0.02-0.50]) and complexity (standardized regression coefficient 0.14 [0.03-0.26]). Variation in strength and direction of associations was observed between subjects for relationships that were significant during group analysis.

CONCLUSIONS

Quantitative EEG characteristics of pediatric early posttraumatic seizures are associated with variable changes in cerebral and systemic physiology, with spectral edge frequency negatively associated with intracranial pressure and peak value frequency positively associated with HR.

Review of Noninvasive Neuromonitoring Modalities in Children II: EEG, qEEG

Critically ill children with acute neurologic dysfunction are at risk for a variety of complications that can be detected by noninvasive bedside neuromonitoring. Continuous electroencephalography (cEEG) is the most widely available and utilized form of neuromonitoring in the pediatric intensive care unit. In this article, we review the role of cEEG and the emerging role of quantitative EEG (qEEG) in this patient population. cEEG has long been established as the gold standard for detecting seizures in critically ill children and assessing treatment response, and its role in background assessment and neuroprognostication after brain injury is also discussed. We explore the emerging utility of both cEEG and qEEG as biomarkers of degree of cerebral dysfunction after specific injuries and their ability to detect both neurologic deterioration and improvement.

Approaches to neuroprotection in pediatric neurocritical care

Acute neurologic injuries represent a common cause of morbidity and mortality in children presenting to the pediatric intensive care unit. After primary neurologic insults, there may be cerebral brain tissue that remains at risk of secondary insults, which can lead to worsening neurologic injury and unfavorable outcomes. A fundamental goal of pediatric neurocritical care is to mitigate the impact of secondary neurologic injury and improve neurologic outcomes for critically ill children. This review describes the physiologic framework by which strategies in pediatric neurocritical care are designed to reduce the impact of secondary brain injury and improve functional outcomes. Here, we present current and emerging strategies for optimizing neuroprotective strategies in critically ill children.

Early Electroencephalographic Features Predicting Cerebral Physiology and Functional Outcomes After Pediatric Traumatic Brain Injury

BACKGROUND

We investigated whether early electroencephalographic features predicted intracranial pressure (ICP), cerebrovascular pressure reactivity, brain tissue oxygenation, and functional outcomes in patients with pediatric traumatic brain injury (TBI).

METHODS

This was a retrospective analysis of a prospective data set of 63 patients with pediatric TBI. Electroencephalographic features were collected in the first 24 h of recording to predict values of ICP, pressure reactivity index (PRx), and brain tissue oxygenation (PbtO2) through the initial 7 days of critical care monitoring, in addition to Glasgow Outcome Scale Extended-Pediatric Revision (GOSE-Peds) scores at 12 months. Electroencephalographic features were averaged over all surface electrodes and included seizures, interictal epileptiform discharges, suppression percentage, complexity, the alpha/delta power ratio, and both absolute asymmetry indices and power in beta (13-20 Hz), alpha (8-13 Hz), theta (4-7 Hz) and delta (0-4 Hz) bands. Demographic data and injury severity scores, such as the Glasgow Coma Scale (GCS) and Pediatric Risk of Mortality III (PRISM III) scores, at presentation were also assessed. Univariate and multiple linear regression with guided stepwise variable selection was used to find combinations of risk factors that best explain variability in ICP, PRx, PbtO2, and GOSE-Peds values, and best fit models were applied to pediatric age strata. We hypothesized that suppression percentage and the alpha/delta power ratio in the first 24 h of recording predict ICP, PRx, PbtO2, and GOSE-Peds values.

RESULTS

Best subset model selection identified that increased suppression percentage and PRISM III scores predicted increased ICP (R2 = 79%, Akaike information criterion [AIC] = 332.30, root mean square error [RMSE] = 6.62), with suppression percentages < 5% (slope =  - 5687.0, p = 0.0001) and ≥ 45% (slope = 9825.9, p = 0.0000) being predictive of dose of intracranial hypertension. When accounting for age and GCS score, increased suppression percentage predicted increased PRx values, suggestive of inefficient cerebrovascular pressure reactivity (R2 = 53%, AIC = 3.93, RMSE = 0.23), with suppression percentages ≥ 5% (p = 0.0033) and ≥ 45% (p = 0.0027) being predictive of median PRx values ≥ 0.3. Lower GCS scores, the presence of seizures, and increased suppression percentages each were independently associated with higher GOSE-Peds scores (R2 = 52%, AIC = 194.04, RMSE = 1.58), suggestive of unfavorable outcomes, with suppression percentages ≥ 5% (p = 0.0005) and ≥ 45% (p = 0.0000) being predictive of GOSE-Peds scores ≥ 5. At the univariate level, no electroencephalographic or clinical feature was associated with differences in PbtO2 values.

CONCLUSIONS

Increased electroencephalographic suppression percentage on the initial day of monitoring may identify patients with pediatric TBI at risk of increased ICP, inefficient cerebrovascular pressure reactivity, and unfavorable outcomes.

Quantitative Electroencephalography After Pediatric Anterior Circulation Stroke

OBJECTIVE

Regional differences were investigated in quantitative EEG (QEEG) characteristics and associations of QEEG to hemodynamics after pediatric acute stroke.

METHODS

Quantitative EEG was analyzed, including power in delta, theta, alpha, and beta bands, alpha-delta power ratio, total power, and spectral edge frequency from 11 children with unilateral, anterior circulation strokes during the first 24 hours of continuous EEG recording. Differences between injured and uninjured hemispheres were assessed using multivariate dynamic structural equations modeling. Dynamic structural equations modeling was applied to six children with hemorrhagic stroke undergoing arterial blood pressure, heart rate, and cerebral oximetry monitoring to investigate associations between hemodynamics with QEEG adjacent to anterior circulation regions.

RESULTS

All patients with acute ischemic stroke ( n = 5) had lower alpha and beta power and spectral edge frequency on injured compared with uninjured regions. This was not consistent after hemorrhagic stroke ( n = 6). All hemorrhagic stroke patients demonstrated negative association of total power with arterial blood pressure within injured regions. No consistency was observed for direction or strength of association in other QEEG measures to arterial blood pressure nor were such consistent relationships observed for any QEEG measure studied in relation to heart rate or cerebral oximetry.

CONCLUSIONS

After pediatric anterior circulation acute ischemic stroke, reduced spectral edge frequency and alpha and beta power can be observed on injured as compared with noninjured regions. After pediatric anterior circulation hemorrhagic stroke, total power can be negatively associated with arterial blood pressure within injured regions. Larger studies are needed to understand conditions in which QEEG patterns manifest and relate to hemodynamics and brain penumbra.

Electroencephalogram in the intensive care unit: a focused look at acute brain injury

Over the past decades, electroencephalography (EEG) has become a widely applied and highly sophisticated brain monitoring tool in a variety of intensive care unit (ICU) settings. The most common indication for EEG monitoring currently is the management of refractory status epilepticus. In addition, a number of studies have associated frequent seizures, including nonconvulsive status epilepticus (NCSE), with worsening secondary brain injury and with worse outcomes. With the widespread utilization of EEG (spot and continuous EEG), rhythmic and periodic patterns that do not fulfill strict seizure criteria have been identified, epidemiologically quantified, and linked to pathophysiological events across a wide spectrum of critical and acute illnesses, including acute brain injury. Increasingly, EEG is not just qualitatively described, but also quantitatively analyzed together with other modalities to generate innovative measurements with possible clinical relevance. In this review, we discuss the current knowledge and emerging applications of EEG in the ICU, including seizure detection, ischemia monitoring, detection of cortical spreading depolarizations, assessment of consciousness and prognostication. We also review some technical aspects and challenges of using EEG in the ICU including the logistics of setting up ICU EEG monitoring in resource-limited settings.

Neurocritical Care and Brain Monitoring

The goal of neurocritical care (NCC) is to improve the outcome of patients with neurologic insults. NCC includes the management of the primary brain injury and prevention of secondary brain injury; this is achieved with standardized clinical care for specific disorders along with neuromonitoring. Neuromonitoring uses multiple modalities, with certain modalities better suited to certain disorders. The term "multimodality monitoring" refers to using multiple modalities at the same time. This article reviews pediatric NCC, the various physiologic parameters used, especially continuous electroencephalographic monitoring.

Evidence-Based Protocols in Child Neurology

Medical care has become more complex as the scientific method has expanded medical knowledge. Medicine is also now practiced across different medical systems of varying complexity, and creating standard treatment guidelines is one way of establishing uniform treatment across these systems. The creation of guidelines ensures the delivery of quality medical care and improved patient outcomes. Evidence-based medicine is the application of scientific research to produce these treatment guidelines. This article shall focus on the current treatment guidelines used for inpatient pediatric neurology.

Intracranial Electroencephalography in Pediatric Severe Traumatic Brain Injury

OBJECTIVES

Electroencephalography is used in neurocritical care for detection of seizures and assessment of cortical function. Due to limited resolution from scalp electroencephalography, important abnormalities may not be readily detectable. We aimed to identify whether intracranial electroencephalography allows for improved methods of monitoring cortical function in children with severe traumatic brain injury.

DESIGN

This is a retrospective cohort study from a prospectively collected clinical database. We investigated the occurrence rate of epileptiform abnormalities detected on intracranial electroencephalography when compared with scalp electroencephalography. We also investigated the strength of association of quantitative electroencephalographic parameters and cerebral perfusion pressure between both intracranial and scalp electroencephalography.

SETTING

This is a single-institution study performed in the Phoenix Children's Hospital PICU.

PATIENTS

Eleven children with severe traumatic brain injury requiring invasive neuromonitoring underwent implantation of a six-contact intracranial electrode as well as continuous surface electroencephalography.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Visual detection of epileptiform abnormalities was performed by pediatric epileptologists. Association of intracranial and scalp electroencephalography total power, alpha percentage, and alpha-delta power ratio to cerebral perfusion pressure was performed using univariate dynamic structural equations modeling. Demographic data were assessed by retrospective analysis. Intracranial and scalp electroencephalography was performed in 11 children. Three of 11 children had observed epileptiform abnormalities on intracranial electroencephalography. Two patients had epileptiform abnormalities identified exclusively on intracranial electroencephalography, and one patient had seizures initiating on intracranial electroencephalography before arising on scalp electroencephalography. Identification of epileptiform abnormalities was associated with subsequent identification of stroke or malignant cerebral edema. We observed statistically significant positive associations between intracranial alpha-delta power ratio to cerebral perfusion pressure in nine of 11 patients with increased strength of association on intracranial compared with scalp recordings.

CONCLUSIONS

These findings suggest that intracranial electroencephalography may be useful for detection of secondary insult development in children with traumatic brain injury.

Approaches to Multimodality Monitoring in Pediatric Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in children. Improved methods of monitoring real-time cerebral physiology are needed to better understand when secondary brain injury develops and what treatment strategies may alleviate or prevent such injury. In this review, we discuss emerging technologies that exist to better understand intracranial pressure (ICP), cerebral blood flow, metabolism, oxygenation and electrical activity. We also discuss approaches to integrating these data as part of a multimodality monitoring strategy to improve patient care.

Clinical trials for pediatric traumatic brain injury: definition of insanity?

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in children both in the United States and throughout the world. Despite valiant efforts and multiple clinical trials completed over the last few decades, there are no high-level recommendations for pediatric TBI available in current guidelines. In this review, the authors explore key findings from the major pediatric clinical trials in children with TBI that have shaped present-day recommendations and the insights gained from them. The authors also offer a perspective on potential efforts to improve the efficacy of future clinical trials in children following TBI.