The use of amplitude integrated electroencephalography for assessing neonatal neurologic injury

Oxidative Stress Biomarkers and Early Brain Activity in Extremely Preterm Infants: A Prospective Cohort Study

Early brain activity, measured using amplitude-integrated EEG (aEEG), is correlated with neurodevelopmental outcome in preterm newborns. F2-isoprostanes (IPs) are early biomarkers predictive for brain damage. We aimed to investigate the relationship between perinatal IPs concentrations and quantitative aEEG measures in preterm newborns. Thirty-nine infants (gestational age (GA) 24–27 ± 6 weeks) who underwent neuromonitoring using aEEG during the first two days after birth were enrolled. The rate of spontaneous activity transients per minute (SAT rate) and inter-SAT interval (ISI) in seconds were computed. Two postnatal time-points were examined: within 12 h (day 1) and between 24 and 48 h (day 2). IPs were measured in plasma from cord blood (cb-IPs) and between 24 and 48 h (pl-IPs). Multivariable regression analyses were performed to assess the correlation between IPs and brain activity. Cb-IPs were not associated with SAT rate and ISI at day 1. Higher pl-IPs were followed by longer ISI (R = 0.68; p = 0.034) and decreased SAT rate (R = 0.58; p = 0.007) at day 2 after adjusting for GA, FiO2 and IVH. Higher pl-IPs levels are associated with decreased functional brain activity. Thus, pl-IPs may represent a useful biomarker of brain vulnerability in high-risk infants.

Predictive value of early amplitude integrated electroencephalogram (aEEG) in sleep related problems in children with perinatal hypoxic-ischemia (HIE)

Background

While great attention has been paid to motor and cognitive impairments in children with neonatal Hypoxic-Ischemic Encephalopathy (HIE), sleep related circadian rhythm problems, although commonly present, are often neglected. Subsequently, no early clinical indicators have been reported to correlate with sleep-related circadian dysfunction during development.

Methods

In this study, we first analyzed patterns of the amplitude integrated electroencephalogram (aEEG) in a cohort of newborns with various degrees of HIE. Next, during follow-ups, we collected information of sleep and circadian related problems in these patients and performed correlation analysis between aEEG parameters and different sleep/circadian disorders.

Results

A total of 101 neonates were included. Our results demonstrated that abnormal aEEG background pattern is significantly correlated with circadian rhythmic (r = 0.289, P = 0.01) and breathing issues during sleep (r = 0.237, P = 0.037). In contrast, the establishment of sleep–wake cycle (SWC) showed no correlation with sleep/circadian problems. Detailed analysis showed that summation of aEEG score, along with low base voltage (r = 0.272, P = 0.017 and r = -0.228, P = 0.048, respectively), correlates with sleep circadian problems. In contrast, background pattern (BP) score highly correlates with sleep breathing problem (r = 0.319, P = 0.004).

Conclusion

Abnormal neonatal aEEG pattern is correlated with circadian related sleep problems. Our study thus provides novel insights into predictive values of aEEG in sleep-related circadian problems in children with HIE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02796-9.

Changes in brain morphology and microstructure in relation to early brain activity in extremely preterm infants

Background and ObjectiveTo investigate the relation of early brain activity with structural (growth of the cortex and cerebellum) and white matter microstructural brain development.MethodsA total of 33 preterm neonates (gestational age 26±1 weeks) without major brain abnormalities were continuously monitored with electroencephalography during the first 48 h of life. Rate of spontaneous activity transients per minute (SAT rate) and inter-SAT interval (ISI) in seconds per minute were calculated. Infants underwent brain magnetic resonance imaging ∼30 (mean 30.5; min: 29.3-max: 32.0) and 40 (41.1; 40.0-41.8) weeks of postmenstrual age. Increase in cerebellar volume, cortical gray matter volume, gyrification index, fractional anisotropy (FA) of posterior limb of the internal capsule, and corpus callosum (CC) were measured.ResultsSAT rate was positively associated with cerebellar growth (P=0.01), volumetric growth of the cortex (P=0.027), increase in gyrification (P=0.043), and increase in FA of the CC (P=0.037). ISI was negatively associated with cerebellar growth (P=0.002).ConclusionsIncreased early brain activity is associated with cerebellar and cortical growth structures with rapid development during preterm life. Higher brain activity is related to FA microstructural changes in the CC, a region responsible for interhemispheric connections. This study underlines the importance of brain activity for microstructural brain development.

Effect of general anesthesia on neonatal aEEG-A cohort study of patients with non-cardiac congenital anomalies

Introduction

The aim of the current study was to determine the effect of general anesthesia on neonatal brain activity using amplitude-integrated EEG (aEEG).

Methods

A prospective cohort study of neonates (January 2013-December 2015), who underwent major neonatal surgery for non-cardiac congenital anomalies. Anesthesia was administered at the discretion of the anesthetist. aEEG monitoring was started six hours preoperatively until 24 hours after surgery. Analysis of classes of aEEG background patterns, ranging from continuous normal voltage to flat trace in six classes, and quantitative EEG-measures, using spontaneous activity transients (SATs) and interSATintervals (ISI), was performed.

Results

In total, 111 neonates were included (36 preterm/75 full-term), age at time of surgery was (median (range) 2 (0–32) days. During anesthesia depression of brain activity was seen, with background patterns ranging from flat trace to discontinuous normal voltage. In most patients brain activity was two background pattern classes lower during anesthesia. After cessation of anesthesia, recovery to preoperative brain activity occurred within 24 hours in 86% of the preterm and 96% of the term infants. Gestational age and the dose of sevoflurane were significantly associated with SAT-rate (F(2,68) = 9.288, p < 0.001) and ISI- durations during surgery (F(3,71) = 12.96, p < 0.001). Background pattern and quantitative EEG-values were not associated with brain lesions (χ2(4) = 2.086, ns).

Conclusion

aEEG shows a variable reduction of brain activity in response to anesthesia in neonates with noncardiac congenital anomalies, with fast recovery after cessation of anesthesia. This reduction is related to gestational age and the dose of sevoflurane. The aEEG offers the opportunity to monitor the depth of anesthesia in the neonate.

A Comparison of the Thompson Encephalopathy Score and Amplitude-Integrated Electroencephalography in Infants with Perinatal Asphyxia and Therapeutic Hypothermia

BACKGROUND

In previous studies clinical signs or amplitude-integrated electroencephalography (aEEG)-based signs of encephalopathy were used to select infants with perinatal asphyxia for treatment with hypothermia.

AIM

The objective of this study was to compare Thompson encephalopathy scores and aEEG, and relate both to outcome.

SUBJECTS AND METHODS

Thompson scores, aEEG, and outcome were compared in 122 infants with perinatal asphyxia and therapeutic hypothermia. Of these 122 infants, 41 died and 7 had an adverse neurodevelopmental outcome. A receiver operating characteristics (ROC) analysis was also performed.

RESULTS

Thompson scores were higher in infants with more abnormal aEEG background patterns (ANOVA, p < 0.001). The ROC analysis demonstrated that a Thompson score of 11 or higher or an aEEG background pattern of continuous low voltage or worse was associated with an adverse outcome (AUC 0.84 for both).

CONCLUSIONS

High Thompson scores and a suppressed aEEG background pattern are associated with an adverse outcome after perinatal asphyxia and therapeutic hypothermia. Further studies are needed to identify the best technique with which to select patients for therapeutic hypothermia.

Are All Amplitude-Integrated Electroencephalogram Systems Equal?

BACKGROUND

Filter and peak detection algorithms implemented in amplitude-integrated electroencephalogram (aEEG) systems are not standardized. New aEEG systems are continuously enriching the market and clinicians are faced with different aEEG devices whose tracings may vary.

OBJECTIVES

The aim of this work was to determine the role of different aEEG systems on quantitative measurements of the aEEG.

METHODS

In this observational study, a single-channel aEEG recording (Olympic CFM 6000) with corresponding EEG signal was obtained from 32 infants at a gestational age of 36-44 weeks. The signals were split into 334 episodes of 4 h. New aEEG tracings were generated using the NicoletOne Reader Software and aEEG emulations with varying filter profiles and peak detection settings. The aEEG amplitude margins and automated annotation of continuous normal voltage (CNV) were compared.

RESULTS

The output of the Olympic and the NicoletOne systems are very similar but not identical; the Spearman rank correlations of the aEEG amplitude margins exceeded 0.9 and the differences in the lower and upper amplitude margins were 1.55 μV (SD 1.47) and -2.12 μV (SD 1.44) on average (n = 309), respectively. The aEEG emulation showed that the differences between the output of the Olympic and the NicoletOne system could be primarily ascribed to the peak detection algorithm. The differences in output can affect automated analyses with agreement rates in CNV detection of 76% (n = 32, positive) and 92% (n = 32, negative) when comparing the Olympic to the NicoletOne outputs.

CONCLUSIONS

Commercial aEEG systems have similar but not identical outputs. Care is advised when interpreting automated aEEG classifications across different devices.

Amplitude-Integrated Electroencephalography Interpretation During Therapeutic Hypothermia: An Educational Program and Novel Teaching Tool

Therapeutic hypothermia (TH) is now considered a standard in tertiary NICUs. Amplitude-integrated electroencephalography (aEEG) is an important adjunct to this therapy and is gaining acceptance for use on the neonatal population. It can be easily incorporated into practice with appropriate education and training. Current publications are lacking regarding nursing care of neonatal patients undergoing th with the use of aEEG. This article presents a broad educational program as well as novel teaching tool for neonatal nurses caring for this population.

Bispectral index and lower margin amplitude of the amplitude-integrated electroencephalogram in neonates

BACKGROUND

The lower margin amplitude (LMA) of the amplitude-integrated electroencephalogram (aEEG) is suppressed in neonates during deep sedation, a feature that is attributed to the bispectral index (BIS) in adults.

OBJECTIVE

We compare the BIS and the LMA of the aEEG in neonates.

METHODS

Thirty neurologically healthy neonates between 37 and 44 weeks postmenstrual age were included in this study. Twenty patients received sedoanalgesic therapy for various reasons. BIS and aEEG recordings were performed simultaneously. The digital data were imported in the numerical software environment Matlab®. The LMA of the aEEG was computed on a 1-min time scale and synchronized with the BIS data. The correlation between the time-dependent variables BIS and LMA was estimated using the Spearman rank correlation index.

RESULTS

The median correlation between BIS and LMA was 0.3. Inclusion of recordings of high signal quality only into analysis improved the median correlation index to 0.6.

CONCLUSIONS

We found a light-to-moderate correlation between BIS and LMA in our study cohort and a good correlation in the subgroup with high signal quality.

Clinical management of seizures in newborns : diagnosis and treatment

Neonatal seizures can be classified as tonic, clonic, myoclonic, and subtle. A clinical diagnosis is not easy as seizures are usually subtle in neonates. In the majority of newborn infants seizures are subclinical. On the other hand, not all abnormal movements identified by clinicians as clinical seizures are accompanied by electroencephalographic seizure discharges in the EEG. Precise incidence is difficult to delineate and depends on study population and criteria used for diagnosis of seizures. Controversy exists as to whether neonatal seizures themselves cause damage to the developing brain, or if the damage is primarily due to the underlying cause of the seizures. As a result of this controversy there is ongoing discussion whether all seizures (both clinical and subclinical) should be treated. In addition, when (sub)clinical seizures are treated, there is no consensus about the most appropriate treatment for neonatal seizures and how to assess the efficacy of treatment. Current therapeutic options to treat neonatal seizures (i.e. primarily first-generation antiepileptic drugs [AEDs]) are relatively ineffective. In practice, phenobarbital still remains the drug of first choice for EEG confirmed or suspected seizures. Benzodiazepines are also used in (phenobarbital) refractory cases. Several (small) studies indicate that lidocaine is an effective drug for refractory seizures as second- or third-line treatment. Although data are scarce, some AEDs with a wide acceptance in adult and pediatric neurology practice are being used to treat neonatal seizures (i.e. second-generation AEDs). These drugs are chemically different from all first-generation AEDs and they have an effect on other pathways so they provide new pharmacological targets for controlling seizures in newborns. Levetiracetam, topiramate, felbamate, bumetanide, lamotrigine and vigabatrin are examples of these second-generation AEDs. There is an urgent need for prospective, randomized, controlled trials to assess the efficacy and safety of these second-generation AEDs in neonates. The aim of this review is to provide an overview of the current knowledge of diagnosis, the effect on brain injury, and the treatment of neonatal seizures.

Systematic characterization of amplitude-integrated EEG signals for monitoring the preterm brain

BACKGROUND

In preterm infants, the amplitude-integrated electroencephalogram (aEEG) is not established in clinical routine. The aim of this study was to derive normative data on aEEG parameters by means of longitudinal characterization and to evaluate the impact of gestational age (GA), postnatal age (PNA), postmenstrual age, sedation, and patent ductus arteriosus (PDA).

METHODS

Recordings from 61 infants with GA 28-31 weeks were obtained during the first 72 h, then weekly until the age of 4 wk. Infants were divided into three groups: (i) no sedation, no PDA, (ii) sedation, no PDA, and (iii) sedation, PDA. Assessed parameters included background activity, cycling, amplitude, and log ratio of the maximum/minimum amplitude.

RESULTS

GA and PNA had a significant impact within 72 h. Sedation modified aEEG, and presence of PDA was associated with reduced aEEG scores within 72 h. The log ratio of the amplitude correlated with GA but was unaffected by sedation and PDA.

CONCLUSION

Evaluation of electrocortical background activity within the first postnatal hours and longitudinally over days and weeks is important to better understand the postnatal factors impacting cerebral function in preterm infants. There is a need to agree on definitions and a standardized reporting system in order to permit comparisons between studies and establish aEEG as a method for routine monitoring of preterm infants.

Effects of midazolam and lidocaine on spectral properties of the EEG in full-term neonates with stroke

Assessment of the neonatal EEG may be hampered by drug-specific changes in electrocortical activity. To quantify effects of a loading dose of midazolam and lidocaine on the EEG frequency spectrum of full-term neonates with perinatal arterial ischemic stroke (PAIS), 11 full-term infants underwent multi-channel amplitude-integrated EEG (aEEG) and EEG recordings. During recording, midazolam and/or lidocaine were administered as anti-epileptic drug. Retrospectively, we performed spectral analysis on 4-h EEG segments around the loading dose. The frequency spectrum was divided in δ (1-4 Hz), θ (4-8 Hz), α (8-13 Hz) and β (13-30 Hz) bands. Midazolam induced immediate suppression of the aEEG background pattern for 30-60 min. Spectral EEG analysis showed decreased total and absolute frequency band powers. Relative δ power decreased, θ power increased while α and β powers remained constant. Lidocaine induced no aEEG background pattern suppression. Total and absolute EEG band powers were unchanged. Relative δ power decreased, θ and α power increased and β power remained constant. Effects of lidocaine were more pronounced in the stroke-affected hemisphere. In conclusions, both drugs induced a shift from low to higher frequency electrocortical activity. Additionally, midazolam reduced total EEG power. These spectral changes differ from those seen in adult studies.

Amplitude-integrated electroencephalography in newborns with inborn errors of metabolism

BACKGROUND

The utility of amplitude-integrated electroencephalography (aEEG) monitoring has been established for patients with neonatal hypoxic-ischemic encephalopathy.

OBJECTIVE

To evaluate the role of aEEG in the diagnostic process and treatment of patients with encephalopathy due to inborn errors of metabolism.

METHODS

Cases collected through an international registry were divided into 5 groups of metabolic disorders. Common aEEG features were sought for each group.

RESULTS

In total, 21/30 (70%) cases had abnormal aEEG background patterns, 18/30 (60%) showed seizure activity. Patients with disorders of energy metabolism, hyperammonemia, and organic/amino acidopathies often showed marked aEEG depression with seizure activity. In contrast, aEEGs of patients with peroxisomal disorders did not show major background abnormalities but seizures were present in 5/6 subjects. We report two features of interest: firstly, two tracings displayed an unusual upward shift of the lower aEEG amplitude margin. Secondly, aEEGs of infants with non-ketotic hyperglycinemia showed a pattern we refer to as 'high-frequency burst-suppression pattern'.

CONCLUSIONS

aEEG in patients with inborn errors of metabolism frequently reveals abnormalities and assists clinicians in the clinical assessment, management and monitoring of these patients.

[Acute neurological complications after pediatric cardiac surgery: still a long way to go]

INTRODUCTION

There has been an increasing concern over the neurological complications associated with congenital heart disease and cardiac surgery.

MATERIAL AND METHODS

We performed a retrospective, case-control, observational review of the postoperative period in the intensive care unit of patients undergoing cardiac surgery over the past 10 years. We selected 2 control patients for each case, matched for surgical complexity.

RESULTS

A total of 900 patients were reviewed. We found 38 neurological complications (4.2%), of which 21 (55.3%) were in the peripheral nervous system and 17 (44.7%) in the central nervous system. The complications involving the central nervous system (1.9% of total) consisted of 8 seizures, 4 cerebrovascular accidents, 4 hypoxic-ischemic encephalopathy events, and 1 reversible neurological deficit. At the time of discharge, 35.3% were symptomatic and 17.6% had died. Patients with neurological complications had a longer bypass time (P=.009), longer aortic cross time (P=.012), longer hospitalization in intensive care (P=.001), longer duration of mechanical ventilation (P=.004) and an increased number of days under inotropic support (P=.001).

CONCLUSIONS

Our incidence of neurological complications after cardiac surgery is similar to that previously described. Clinical seizures are the most common complication. Central nervous system complications are associated with a higher morbidity and hospitalization time. Units caring for patients with congenital heart disease must implement neurological monitoring during and after cardiac surgery to prevent and to detect these complications earlier.

Decreased aEEG continuity and baseline variability in the first 48 hours of life associated with poor short-term outcome in neonates born before 29 weeks gestation

Amplitude-integrated electroencephalography (aEEG) provides us with a method of assessing brain activity in critically ill neonates. In extremely premature neonates, the aEEG trace is predominantly discontinuous, making it difficult to distinguish between a "normal" and "abnormal" trace. We measured aEEG activity in the first 48 h of life in neonates born before 29-wk gestation and used both visual and quantitative analysis of the aEEG data to assess differences in neonates with poor short-term outcome [death or peri/intraventricular hemorrhage (P/IVH)] compared with those who survived without P/IVH to identify features of an abnormal aEEG. On quantitative analysis, EEG continuity <80% at 10-microV level was a sensitive and specific marker of poor short-term outcome. By using this marker, we identified 83% of neonates who died or developed grade 3 or 4 IVH and 60% of neonates who developed grades 1 or 2 IVH, with a positive predictive value for death or any IVH of 73% and a negative predictive value of 86%. Absence of sleep-wake cycling with baseline variability <2 microV was the strongest predictor of outcome using visual analysis alone.

Approach to seizures in the neonatal period: a European perspective

In the neonatal period, seizures rank among the most common neurological symptoms, often indicating an underlying serious neurological condition. It is remarkable that although new tools have been incorporated into the diagnosis of neonatal seizures, there is no consensus about the therapeutic approach among different doctors and institutions. Hence, although phenobarbital is still considered the initial drug of choice, the protocols reported in the literature show a great variability in the approach to treatment of refractory seizures. We used a questionnaire to gain information regarding the treatment of seizures in the neonatal period in different European institutions.

CONCLUSION

We conclude that phenobarbital is still the initial drug of choice followed by benzodiazepines, except in preterm infants with a birth weight below 1800 g. In refractory seizures, the use of continuous lidocaine infusion is most common. Of note, clinical studies with newer drugs have been mostly performed in the United States but not in Europe.

Brain monitoring in neonates

Continuous EEG monitoring with amplitude-integrated electroencephalography (aEEG) has become a part of the routine neurological care in the neonatal unit, especially in full-term infants with hypoxia-ischemia and in infants suspected of seizures. Its prognostic value after birth asphyxia is well established and seizure detection has improved with the new digital aEEG devices with access to the "real" EEG, and even with seizure detection in some devices. Recent experience shows that aEEG monitoring also appears to be very helpful in premature infants. One has to be aware of possible artefacts, like ECG or movement artefacts, which can lead to misinterpretation of the background pattern. Cerebral oximetry records regional saturation of the brain using Near Infrared Spectroscopy (NIRS) and provides a non-invasive method to continuously monitor brain oxygen imbalance. Cerebral oximetry is increasingly being used as a trend monitor in critically ill neonates. Its usefulness has been assessed in cardiac surgery, patent ductus arteriosus, hypoxia-ischemia and ventilation with high mean airway pressures. A combination of both monitoring modalities will probably become the future for neonatal neuromonitoring.