Current Status of Continuous Electroencephalographic Monitoring in Critically Ill Children

Evaluation of Nonconvulsive Status Epilepticus and Nonconvulsive Seizures in a Pediatric Intensive Care Unit

We aimed to identify nonconvulsive seizures (NCS) and nonconvulsive status epilepticus (NCSE) in a pediatric intensive care unit (PICU). A prospective cohort study on 35 patients who underwent continuous electroencephalographic monitoring in the PICU was done. The patients were evaluated to collect data of their demographics, clinical diagnoses, clinical seizures by electroencephalography, and neuroimaging findings. One case with NCSE and 4 cases with NCS were diagnosed among the 35 patients. The etiology of the patient with NCSE showed antiepileptic drug (AED) withdrawal. The etiology of the patients with NCS included electrical injury, head trauma, subarachnoid hemorrhage, and pneumonia. The findings suggest that younger age, epilepsy, acute structural brain abnormalities, abrupt cessation of AED, and clinically overt seizures before NCSE/NCS are associated with significant risk for NCS/NCSE. In addition, the electrical injury may also be considered as a risk factor for electrographic seizure though such a case has not yet been reported.

A Dynamic Balance between Neuronal Death and Clearance in an in Vitro Model of Acute Brain Injury

In in vitro models of acute brain injury, neuronal death may overwhelm the capacity for microglial phagocytosis, creating a queue of dying neurons awaiting clearance. Neurons undergoing programmed cell death are in this queue, and are the most visible and frequently quantified measure of neuronal death after injury. However, the size of this queue should be equally sensitive to changes in neuronal death and the rate of phagocytosis. Using rodent organotypic hippocampal slice cultures as a model of acute perinatal brain injury, serial imaging demonstrated that the capacity for microglial phagocytosis of dying neurons was overwhelmed for 2 weeks. Altering phagocytosis rates (e.g., by changing the number of microglia) dramatically changed the number of visibly dying neurons. Similar effects were generated when the visibility of dying neurons was altered by changing the membrane permeability for stains that label dying neurons. Canonically neuroprotective interventions, such as seizure blockade, and neurotoxic maneuvers, such as perinatal ethanol exposure, were mediated by effects on microglial activity and the membrane permeability of neurons undergoing programmed cell death. These canonically neuroprotective and neurotoxic interventions had either no or opposing effects on healthy surviving neurons identified by the ongoing expression of transgenic fluorescent proteins.SIGNIFICANCE STATEMENT In in vitro models of acute brain injury, microglial phagocytosis is overwhelmed by the number of dying cells. Under these conditions, the assumptions on which assays for neuroprotective and neurotoxic effects are based are no longer valid. Thus, longitudinal assays of healthy cells, such as serial assessment of the fluorescence emission of transgenically expressed proteins, provide more accurate estimates of cell death than do single-time point anatomic or biochemical assays of the number of dying neurons. More accurate estimates of death rates in vitro will increase the translatability of preclinical studies of neuroprotection and neurotoxicity.

A dynamic balance between neuronal death and clearance after acute brain injury

After acute brain injury, neuronal apoptosis may overwhelm the capacity for microglial phagocytosis, creating a queue of dying neurons awaiting clearance. The size of this queue should be equally sensitive to changes in neuronal death and the rate of phagocytosis. Using rodent organotypic hippocampal slice cultures as a model of acute perinatal brain injury, serial imaging demonstrated that the capacity for microglial phagocytosis of dying neurons was overwhelmed for two weeks. Altering phagocytosis rates, e.g. by changing the number of microglia, dramatically changed the number of visibly dying neurons. Similar effects were generated when the visibility of dying neurons was altered by changing the membrane permeability for vital stains. Canonically neuroprotective interventions such as seizure blockade and neurotoxic maneuvers such as perinatal ethanol exposure were mediated by effects on microglial activity and the membrane permeability of apoptotic neurons, and had either no or opposing effects on healthy surviving neurons.

Significance

After acute brain injury, microglial phagocytosis is overwhelmed by the number of dying cells. Under these conditions, the assumptions on which assays for neuroprotective and neurotoxic effects are based are no longer valid. Thus longitudinal assays of healthy cells, such as assessment of the fluorescence emission of transgenically-expressed proteins, provide more accurate estimates of cell death than do single-time-point anatomical or biochemical assays. More accurate estimates of death rates will increase the translatability of preclinical studies of neuroprotection and neurotoxicity.

VEEG monitoring and electrographic seizures in 232 pediatric patients in ICU at a tertiary hospital in China

Objectives

To investigate neonatal electroencephalography (EEG) background activity and electrographic seizures in patients in the pediatric intensive care unit (PICU) who underwent bedside video-electroencephalography (vEEG) monitoring.

Methods

A total of 232 pediatric patients admitted or transferred to PICU that underwent vEEG monitoring were retrospectively enrolled in this study, and electrographic status epilepticus was observed after vEEG monitoring.

Results

The median age was 1.56 years [95% confidence interval (CI) = 1.12-2.44]. Electrographic seizures occurred in 88 patients (37.9%), out of which 36 cases (40.9%) had electrographic status epilepticus. Prior epileptic encephalopathy diagnosis [odds ratio (OR) = 6.57, 95% CI = 1.91-22.59, p = 0.003], interictal epileptiform discharges (OR = 46.82, 95%CI = 5.31-412.86, p = 0.0005), slow disorganized EEG background (OR = 11.92, 95%CI = 1.31-108.71, p = 0.028), and burst-suppression EEG background (OR = 23.64, 95%CI = 1.71-327.57, p = 0.018) were the risk factors for electrographic seizures' occurrence. Of the 232 patients, the condition of 179 (77.2%) patients improved and they were discharged, 34 cases (14.7%) were withdrawn, and 18 cases (7.8%) died. The in-hospital death rate was 47.6% (10 in 21 cases) in patients with attenuated/featureless, compared to 0/23 with normal EEG background.

Conclusions

Electrographic status epilepticus occurs in more than one-third of patients with electrographic seizures. vEEG is an efficient method to determine electrographic seizures in children. Abnormal EEG background activity is associated with both electrographic seizures' occurrence and unfavorable in-hospital outcomes.

Continuous Video Electroencephalography (EEG) for Event Characterization in Critically Ill Children

OBJECTIVE

To determine features of paroxysmal events and background electroencephalographic (EEG) abnormalities associated with electroclinical seizures in critically ill children who undergo continuous video EEG to characterize clinical events.

METHODS

This is a prospective study of critically ill children from July 2016 to October 2018. Non-neonates with continuous video EEG indication to characterize a clinical event were included. Patients with continuous video EEG to assess for subclinical seizures due to unexplained encephalopathy and those whose event of concern were not captured on continuous video EEG were excluded. The event to be characterized was taken from documented descriptions of health care providers and classified as motor, ocular, orobuccal, autonomic, and other. In patients with more than 1 component to their paroxysmal event, the events were classified as motor plus and nonmotor plus.

RESULTS

One hundred patients met inclusion and exclusion criteria, with electroclinical seizures captured in 30% (30/100). The most common event to be characterized was an autonomic event in 32% (32/100). Asymmetry and epileptiform discharges were associated with electroclinical seizures (odds ratio [OR] 2.7, 95% confidence interval [CI] 1.1-6.5, P = .03; and OR 12.5, 95% CI 4.4-35.6, P < .0001). Autonomic events alone, particularly unexplained vital sign changes, were not associated with electroclinical seizures (OR 0.3, 95% CI 0.11-0.93, P = .03).

CONCLUSIONS

Isolated autonomic events are unlikely to be electroclinical seizures. Details of the paroxysmal events in question can help decide which patient will benefit most from continuous video EEG based on institutional resources.