Lidocaine response rate in aEEG-confirmed neonatal seizures: Retrospective study of 413 full-term and preterm infants

OBJECTIVE

To investigate the seizure response rate to lidocaine in a large cohort of infants who received lidocaine as second- or third-line antiepileptic drug (AED) for neonatal seizures.

METHODS

Full-term (n = 319) and preterm (n = 94) infants, who received lidocaine for neonatal seizures confirmed on amplitude-integrated EEG (aEEG), were studied retrospectively (January 1992-December 2012). Based on aEEG findings, the response was defined as good (>4 h no seizures, no need for rescue medication); intermediate (0-2 h no seizures, but rescue medication needed after 2-4 h); or no clear response (rescue medication needed <2 h).

RESULTS

Lidocaine had a good or intermediate effect in 71.4%. The response rate was significantly lower in preterm (55.3%) than in full-term infants (76.1%, p < 0.001). In full-term infants the response to lidocaine was significantly better than midazolam as second-line AED (21.4% vs. 12.7%, p = 0.049), and there was a trend for a higher response rate as third-line AED (67.6% vs. 57%, p = 0.086). Both lidocaine and midazolam had a higher response rate as third-line AED than as second-line AED (p < 0.001). Factors associated with a good response to lidocaine were the following: higher gestational age, longer time between start of first seizure and administration of lidocaine, lidocaine as third-line AED, use of new lidocaine regimens, diagnosis of stroke, use of digital aEEG, and hypothermia. Multivariable analysis of seizure response to lidocaine included lidocaine as second- or third-line AED and seizure etiology.

SIGNIFICANCE

Seizure response to lidocaine was seen in ~70%. The response rate was influenced by gestational age, underlying etiology, and timing of administration. Lidocaine had a significantly higher response rate than midazolam as second-line AED, and there was a trend for a higher response rate as third-line AED. Both lidocaine and midazolam had a higher response rate as third-line compared to second-line AED, which could be due to a pharmacologic synergistic mechanism between the two drugs.

Glial Fibrillary Acidic Protein Is Not an Early Marker of Injury in Perinatal Asphyxia and Hypoxic-Ischemic Encephalopathy

Brain-specific glial fibrillary acidic protein (GFAP) has been suggested as a potential biomarker for hypoxic ischemic encephalopathy (HIE) in newborns (1, 2). Previous studies have shown increased levels in post-natal blood samples. However, its ability to guide therapeutic intervention in HIE is unknown. Therapeutic hypothermia for HIE must be initiated within 6 h of birth, therefore a clinically useful marker of injury would have to be available immediately following delivery. The goal of our study was to examine the ability of GFAP to predict grade of encephalopathy and neurological outcome when measured in umbilical cord blood (UCB). Infants with suspected perinatal asphyxia (PA) and HIE were enrolled in a single, tertiary maternity hospital, where UCB was drawn, processed, and bio-banked at birth. Expression levels of GFAP were measured by ELISA. In total, 169 infants (83 controls, 56 PA, 30 HIE) were included in the study. GFAP levels were not increased in UCB of case infants (PA/HIE) when compared to healthy controls or when divided into specific grades of HIE. Additionally, no correlation was found between UCB levels of GFAP and outcome at 36 months.

Treating disorders of the neonatal central nervous system: pharmacokinetic and pharmacodynamic considerations with a focus on antiepileptics

A major consideration in the treatment of neonatal disorders is that the selected drug, dose and dosage frequency is safe, effective and appropriate for the intended patient population. Thus, a thorough knowledge of the pharmacokinetics and pharmacodynamics of the chosen drug within the patient population is essential. In paediatric and neonatal populations two additional challenges can often complicate drug treatment - the inherently greater physiological variability, and a lack of robust clinical evidence of therapeutic range. There has traditionally been an overreliance in paediatric medicine on extrapolating doses from adult values by adjusting for bodyweight or body surface area, but many other sources of variability exist which complicate the choice of dose in neonates. The lack of reliable drug dosage data in neonates has been highlighted by regulatory authorities, as only ~50% of the most commonly used paediatric medicines have been examined in a paediatric population. Moreover, there is a paucity of information on the pharmacokinetic parameters which affect drug concentrations in different body tissues, and pharmacodynamic responses to drugs in the neonate. Thus, in the present review, we draw attention to the main pharmacokinetic factors that influence the unbound brain concentration of neuroactive drugs. Moreover, the pharmacodynamic differences between neonates and adults that affect the activity of centrally-acting therapeutic agents are briefly examined, with a particular emphasis on antiepileptic drugs.

Effects of Fractional Inspired Oxygen on Cerebral Oxygenation in Preterm Infants following Delivery

OBJECTIVES

To explore regional cerebral oxygen saturations (rcSO2) in preterm neonates initially stabilized with 0.3 fractionated inspired oxygen (FiO2) concentrations. We hypothesized that those infants who received >0.3 FiO2 during stabilization following delivery would have relatively higher rcSO2 postdelivery compared with those stabilized with a lower FiO2.

STUDY DESIGN

A single center prospective observational study of 47 infants born before 32 weeks. Using near infrared spectroscopy, rcSO2 values were recorded immediately after birth. All preterm infants were initially given 0.3 FiO2 and were divided into 2 groups according to subsequent FiO2 requirements of either ≤0.3 or >0.3 FiO2. Using a mixed-effects model, we compared the difference between the groups over time. Also, the area measures below 55% (hypoxia) and above 85% (hyperoxia) were compared between the groups.

RESULTS

The mean (SD) gestation was 29.4 (1.6) weeks and the mean (SD) weight was 1.3 (0.4) kg. Less than one-half of the infants (20/45; 43%) required ≤0.3 FiO2. In the delivery suite, the median (IQR) rcSO2 in the low and high FiO2 groups were 81% (66%-86%) and 72% (62%-86%), respectively. Patients in the high FiO2 group had a larger rcSO2 area below 55% (P = .01). There was a significant difference in rcSO2 between the groups (P < .05), with the low group having higher rcSO2 values initially, but this difference changed over time. In the neonatal intensive care unit (NICU), rcSO2 values were lower by 7.1% (CI 12.13 to 2.06%) P = .008 in the high FiO2 group.

CONCLUSIONS

Infants given >0.3 FiO2 had more cerebral hypoxia than infants requiring ≤0.3 FiO2 but no difference in the degree of cerebral hyperoxia, both in the delivery suite and the NICU. This suggests that a more rapid increase in oxygen titration maybe be required initially for preterm infants.

The temporal characteristics of seizures in neonatal hypoxic ischemic encephalopathy treated with hypothermia

PURPOSE

The characteristics of electrographic seizures in newborns with hypoxic-ischaemic encephalopathy (HIE) treated with therapeutic hypothermia (TH) are poorly described. This retrospective, observational study provides reference data on the characteristics of seizures and their evolution over time in newborns with HIE receiving whole-body TH.

METHOD

The cohort under analysis included 23 infants with HIE and seizures defined by multi-channel EEG recordings. Clinical presentation, details of TH and antiepileptic drugs used were recorded. Time from first to last-recorded electrographic seizure (seizure period) was calculated. Temporal characteristics of seizures - total burden, duration, number, burden in minutes per hour, distribution of burden over time (temporal evolution), time from seizure onset to maximum seizure burden (Tmsb), T1, and time from Tmsb to seizure offset, T2 - were analysed.

RESULTS

The median age at electrographic seizure onset was 13.1h (IQR: 11.4 to 22.0). Tmsb was reached at a median age of 19.4 hours (IQR: 12.2 to 29.7). Median seizure period was 16.5h (IQR: 7.0 to 49.7), median number of seizures per hour was 1.9 (IQR: 1.0 to 3.3). The seizure burden was 4.0 min/h (IQR: 2.0 to 7.0). There was no consistent pattern in the temporal evolution of seizures in neonates treated with TH. The skewness was neither positive nor negative (p-value=0.15), there was no difference between the duration of T1 and T2 (p-value=0.09) and no difference in the seizure burden between T1 and T2 (p=0.09). There was an association between Tmsb and Phenobarbital (PB) administration (r=0.76, p-value<0.001).

CONCLUSION

There is no consistent temporal evolution of seizure burden in neonates treated with TH. Seizures are diffuse, and their characteristics are variable.

Robustness of time frequency distribution based features for automated neonatal EEG seizure detection

In this paper we examined the robustness of a feature-set based on time-frequency distributions (TFDs) for neonatal EEG seizure detection. This feature-set was originally proposed in literature for neonatal seizure detection using a support vector machine (SVM). We tested the performance of this feature-set with a smoothed Wigner-Ville distribution and modified B distribution as the underlying TFDs. The seizure detection system using time-frequency signal and image processing features from the TFD of the EEG signal using modified B distribution was able to achieve a median receiver operator characteristic area of 0.96 (IQR 0.91-0.98) tested on a large clinical dataset of 826 h of EEG data from 18 full-term newborns with 1389 seizures. The mean AUC was 0.93.

Interobserver agreement for neonatal seizure detection using multichannel EEG

Objective

To determine the interobserver agreement (IOA) of neonatal seizure detection using the gold standard of conventional, multichannel EEG.

Methods

A cohort of full‐term neonates at risk of acute encephalopathy was included in this prospective study. The EEG recordings of these neonates were independently reviewed for seizures by three international experts. The IOA was estimated using statistical measures including Fleiss' kappa and percentage agreement assessed over seizure events (event basis) and seizure duration (temporal basis).

Results

A total of 4066 h of EEG recordings from 70 neonates were reviewed with an average of 2555 seizures detected. The IOA was high with temporal assessment resulting in a kappa of 0.827 (95% CI: 0.769–0.865; n = 70). The median agreement was 83.0% (interquartile range [IQR]: 76.6–89.5%; n = 33) for seizure and 99.7% (IQR: 98.9–99.8%; n = 70) for nonseizure EEG. Analysis of events showed a median agreement of 83.0% (IQR: 72.9–86.6%; n = 33) for seizures with 0.018 disagreements per hour (IQR: 0.000–0.090 per hour; n = 70). Observers were more likely to disagree when a seizure was less than 30 sec. Overall, 33 neonates were diagnosed with seizures and 28 neonates were not, by all three observers. Of the remaining nine neonates with contradictory EEG detections, seven presented with low total seizure burden.

Interpretation

The IOA is high among experts for the detection of neonatal seizures using conventional, multichannel EEG. Agreement is reduced when seizures are rare or have short duration. These findings support EEG‐based decision making in the neonatal intensive care unit, inform EEG interpretation guidelines, and provide benchmarks for seizure detection algorithms.

Effects of hypoxia-induced neonatal seizures on acute hippocampal injury and later-life seizure susceptibility and anxiety-related behavior in mice

Seizures are common during the neonatal period, often due to hypoxic-ischemic encephalopathy and may contribute to acute brain injury and the subsequent development of cognitive deficits and childhood epilepsy. Here we explored short- and long-term consequences of neonatal hypoxia-induced seizures in 7 day old C57BL/6J mice. Seizure activity, molecular markers of hypoxia and histological injury were investigated acutely after hypoxia and response to chemoconvulsants and animal behaviour was explored at adulthood. Hypoxia was induced by exposing pups to 5% oxygen for 15 min (global hypoxia). Electrographically defined seizures with behavioral correlates occurred in 95% of these animals and seizures persisted for many minutes after restitution of normoxia. There was minimal morbidity or mortality. Pre- or post-hypoxia injection of phenobarbital (50mg/kg) had limited efficacy at suppressing seizures. The hippocampus from neonatal hypoxia-seizure mice displayed increased expression of vascular endothelial growth factor and the immediate early gene c-fos, minimal histological evidence of cell injury and activation of caspase-3 in scattered neurons. Behavioral analysis of mice five weeks after hypoxia-induced seizures detected novel anxiety-related and other behaviors, while performance in a spatial memory test was similar to controls. Seizure threshold tests with kainic acid at six weeks revealed that mice previously subject to neonatal hypoxia-induced seizures developed earlier, more frequent and longer-duration seizures. This study defines a set of electro-clinical, molecular, pharmacological and behavioral consequences of hypoxia-induced seizures that indicate short- and long-term deleterious outcomes and may be a useful model to investigate the pathophysiology and treatment of neonatal seizures in humans.

Downregulation of Umbilical Cord Blood Levels of miR-374a in Neonatal Hypoxic Ischemic Encephalopathy

OBJECTIVE

To investigate the expression profile of microRNA (miRNA) in umbilical cord blood from infants with hypoxic ischemic encephalopathy (HIE).

STUDY DESIGN

Full-term infants with perinatal asphyxia were identified under strict enrollment criteria. Degree of encephalopathy was defined using both continuous multichannel electroencephalogram in the first 24 hours of life and modified Sarnat score. Seventy infants (18 controls, 33 with perinatal asphyxia without HIE, and 19 infants with HIE [further graded as 13 mild, 2 moderate, and 4 severe]) were included in the study. MiRNA expression profiles were determined using a microarray assay and confirmed using quantitative real-time polymerase chain reaction.

RESULTS

Seventy miRNAs were differentially expressed between case and control groups. Of these hsa-miR-374a was the most significantly downregulated in infants with HIE vs controls. Validation of hsa-miR-374a expression using quantitative real-time polymerase chain reaction confirmed a significant reduction in expression among infants with HIE compared with those with perinatal asphyxia and healthy controls (mean relative quantification [SD] = 0.52 [0.37] vs 1.10 [1.52] vs 1.76 [1.69], P < .02).

CONCLUSIONS

We have shown a significant step-wise downregulation of hsa-miR-374a expression in cord blood of infants with perinatal asphyxia and subsequent HIE.

Validation of an automated seizure detection algorithm for term neonates

OBJECTIVE

The objective of this study was to validate the performance of a seizure detection algorithm (SDA) developed by our group, on previously unseen, prolonged, unedited EEG recordings from 70 babies from 2 centres.

METHODS

EEGs of 70 babies (35 seizure, 35 non-seizure) were annotated for seizures by experts as the gold standard. The SDA was tested on the EEGs at a range of sensitivity settings. Annotations from the expert and SDA were compared using event and epoch based metrics. The effect of seizure duration on SDA performance was also analysed.

RESULTS

Between sensitivity settings of 0.5 and 0.3, the algorithm achieved seizure detection rates of 52.6-75.0%, with false detection (FD) rates of 0.04-0.36FD/h for event based analysis, which was deemed to be acceptable in a clinical environment. Time based comparison of expert and SDA annotations using Cohen's Kappa Index revealed a best performing SDA threshold of 0.4 (Kappa 0.630). The SDA showed improved detection performance with longer seizures.

CONCLUSION

The SDA achieved promising performance and warrants further testing in a live clinical evaluation.

SIGNIFICANCE

The SDA has the potential to improve seizure detection and provide a robust tool for comparing treatment regimens.

Neonatal seizure detection using atomic decomposition with a novel dictionary

Atomic decomposition (AD) can be used to efficiently decompose an arbitrary signal. In this paper, we present a method to detect neonatal electroencephalogram (EEG) seizure based on AD via orthogonal matching pursuit using a novel, application-specific, dictionary. The dictionary consists of pseudoperiodic Duffing oscillator atoms which are designed to be coherent with the seizure epochs. The relative structural complexity (a measure of the rate of convergence of AD) is used as the sole feature for seizure detection. The proposed feature was tested on a large clinical dataset of 826 h of EEG data from 18 full-term newborns with 1389 seizures. The seizure detection system using the proposed dictionary was able to achieve a median receiver operator characteristic area of 0.91 (IQR 0.87-0.95) across 18 neonates.

Bumetanide for the treatment of seizures in newborn babies with hypoxic ischaemic encephalopathy (NEMO): an open-label, dose finding, and feasibility phase 1/2 trial

BACKGROUND

Preclinical data suggest that the loop-diuretic bumetanide might be an effective treatment for neonatal seizures. We aimed to assess dose and feasibility of intravenous bumetanide as an add-on to phenobarbital for treatment of neonatal seizures.

METHODS

In this open-label, dose finding, and feasibility phase 1/2 trial, we recruited full-term infants younger than 48 h who had hypoxic ischaemic encephalopathy and electrographic seizures not responding to a loading-dose of phenobarbital from eight neonatal intensive care units across Europe. Newborn babies were allocated to receive an additional dose of phenobarbital and one of four bumetanide dose levels by use of a bivariate Bayesian sequential dose-escalation design to assess safety and efficacy. We assessed adverse events, pharmacokinetics, and seizure burden during 48 h continuous electroencephalogram (EEG) monitoring. The primary efficacy endpoint was a reduction in electrographic seizure burden of more than 80% without the need for rescue antiepileptic drugs in more than 50% of infants. The trial is registered with ClinicalTrials.gov, number NCT01434225.

FINDINGS

Between Sept 1, 2011, and Sept 28, 2013, we screened 30 infants who had electrographic seizures due to hypoxic ischaemic encephalopathy. 14 of these infants (10 boys) were included in the study (dose allocation: 0·05 mg/kg, n=4; 0·1 mg/kg, n=3; 0·2 mg/kg, n=6; 0·3 mg/kg, n=1). All babies received at least one dose of bumetanide with the second dose of phenobarbital; three were withdrawn for reasons unrelated to bumetanide, and one because of dehydration. All but one infant also received aminoglycosides. Five infants met EEG criteria for seizure reduction (one on 0·05 mg/kg, one on 0·1 mg/kg and three on 0·2 mg/kg), and only two did not need rescue antiepileptic drugs (ie, met rescue criteria; one on 0·05 mg/kg and one on 0·3 mg/kg). We recorded no short-term dose-limiting toxic effects, but three of 11 surviving infants had hearing impairment confirmed on auditory testing between 17 and 108 days of age. The most common non-serious adverse reactions were moderate dehydration in one, mild hypotension in seven, and mild to moderate electrolyte disturbances in 12 infants. The trial was stopped early because of serious adverse reactions and limited evidence for seizure reduction.

INTERPRETATION

Our findings suggest that bumetanide as an add-on to phenobarbital does not improve seizure control in newborn infants who have hypoxic ischaemic encephalopathy and might increase the risk of hearing loss, highlighting the risks associated with the off-label use of drugs in newborn infants before safety assessment in controlled trials.

FUNDING

European Community's Seventh Framework Programme.

Overcoming the practical challenges of electroencephalography for very preterm infants in the neonatal intensive care unit

Aim

Long‐term electroencephalogram (EEG) recording is increasingly being used in the neonatal period, but application and maintenance of the EEG electrodes is challenging, especially in preterm infants. This study proposes a practical method of electrode application that can be used in the neonatal intensive care unit (NICU).

Methods

EEG recording in preterm infants of <32 weeks of gestational age is often challenging and requires careful preparation and strict adherence to NICU protocols. An effective technique for EEG application in preterm infants is to use prepackaged, sterile, disposable, flat‐surfaced EEG electrodes. The use of these electrodes in combination with a continuous positive airway pressure hat provides good security for electrodes and good quality EEG recordings. It also limits the handling of the infant, while strictly adhering to infection control policies.

Results

Long‐term monitoring for >72 h has been achieved using this technique. Important steps to consider are efficient preparation of the recording machine and materials, careful electrode application and infection control.

Conclusion

A fast and effective method of EEG electrode placement is required for neonatal EEG monitoring. The practical techniques described in this article outline a reliable method of EEG electrode placement, suitable for even extremely preterm infants.

The effect of organic anion transporter 3 inhibitor probenecid on bumetanide levels in the brain: an integrated in vivo microdialysis study in the rat

Objectives

Recent data highlight the potential of bumetanide as a treatment for neonatal seizures and autism, as it facilitates the excitatory to inhibitory switch in gamma-aminobutyric acid signalling. This study examines the extent of blood-brain barrier (BBB) permeation of bumetanide, a key determinant of the efficacy of centrally acting drugs. Furthermore, the impact of efflux transporter organic anion transporter 3 (oat3) inhibition on bumetanide pharmacokinetics was investigated.

Methods

Bumetanide levels in extracellular fluid (ECF) and plasma in the presence and absence of oat3 inhibitor probenecid were monitored using integrated microdialysis.

Key findings

Following a bumetanide bolus/continuous infusion of 10 mg/kg and 6 mg/kg/h, bumetanide was detected in hippocampal ECF at the estimated concentration of 131 ± 55 ng/ml. Plasma bumetanide levels were ∼20 mg/l at steady state. Coadministration of probenecid resulted in an increase in bumetanide levels in both ECF and plasma, indicating that oat3 inhibition influences the pharmacokinetics of bumetanide primarily in the periphery.

Conclusion

Although bumetanide reached detectable levels in hippocampal ECF, bumetanide concentration in ECF was low relative to systemic concentration. Oat3 inhibition by probenecid resulted in increased bumetanide concentrations in brain and plasma. As an acute treatment in neonatal seizures, the bumetanide/probenecid combination may hold therapeutic potential.

Automated analysis of multi-channel EEG in preterm infants

OBJECTIVE

To develop and validate two automatic methods for the detection of burst and interburst periods in preterm eight-channel electroencephalographs (EEG). To perform a detailed analysis of interobserver agreement on burst and interburst periods and use this as a benchmark for the performance of the automatic methods. To examine mathematical features of the EEG signal and their potential correlation with gestational age.

METHODS

Multi-channel EEG from 36 infants, born at less than 30 weeks gestation was utilised, with a 10 min artifact-free epoch selected for each subject. Three independent expert observers annotated all EEG activity bursts in the dataset. Two automatic algorithms for burst/interburst detection were applied to the EEG data and their performances were analysed and compared with interobserver agreement. A total of 12 mathematical features of the EEG signal were calculated and correlated with gestational age.

RESULTS

The mean interobserver agreement was found to be 77% while mean algorithm/observer agreement was 81%. Six of the mathematical features calculated (spectral entropy, Higuchi fractal dimension, spectral edge frequency, variance, extrema median and Hilberts transform amplitude) were found to have significant correlation with gestational age.

CONCLUSIONS

Automatic detection of burst/interburst periods has been performed in multi-channel EEG of 36 preterm infants. The algorithm agreement with expert observers is found to be on a par with interobserver agreement. Mathematical features of EEG have been calculated which show significant correlation with gestational age.

SIGNIFICANCE

Automatic analysis of preterm multi-channel EEG is possible. The methods described here have the potential to be incorporated into a fully automatic system to quantitatively assess brain maturity from preterm EEG.

Early postnatal EEG features of perinatal arterial ischaemic stroke with seizures

Background

Stroke is the second most common cause of seizures in term neonates and is associated with abnormal long-term neurodevelopmental outcome in some cases.

Objective

To aid diagnosis earlier in the postnatal period, our aim was to describe the characteristic EEG patterns in term neonates with perinatal arterial ischaemic stroke (PAIS) seizures.

Design

Retrospective observational study.

Patients

Neonates >37 weeks born between 2003 and 2011 in two hospitals.

Method

Continuous multichannel video-EEG was used to analyze the background patterns and characteristics of seizures. Each EEG was assessed for continuity, symmetry, characteristic features and sleep cycling; morphology of electrographic seizures was also examined. Each seizure was categorized as electrographic-only or electroclinical; the percentage of seizure events for each seizure type was also summarized.

Results

Nine neonates with PAIS seizures and EEG monitoring were identified. While EEG continuity was present in all cases, the background pattern showed suppression over the infarcted side; this was quite marked (>50% amplitude reduction) when the lesion was large. Characteristic unilateral bursts of theta activity with sharp or spike waves intermixed were seen in all cases. Sleep cycling was generally present but was more disturbed over the infarcted side. Seizures demonstrated a characteristic pattern; focal sharp waves/spike-polyspikes were seen at frequency of 1–2 Hz and phase reversal over the central region was common. Electrographic-only seizure events were more frequent compared to electroclinical seizure events (78 vs 22%).

Conclusions

Focal electrographic and electroclinical seizures with ipsilateral suppression of the background activity and focal sharp waves are strong indicators of PAIS. Approximately 80% of seizure events were the result of clinically unsuspected seizures in neonates with PAIS. Prolonged and continuous multichannel video-EEG monitoring is advocated for adequate seizure surveillance.

Global suppression of electrocortical activity in unilateral perinatal thalamic stroke

We present an unusual case of persistent generalized electroencephalography (EEG) suppression and right-sided clonic seizures in a male infant born at 40(+2) weeks' gestation, birthweight 3240g, with an isolated unilateral thalamic stroke. The EEG at 13 hours after birth showed a generalized very low amplitude background pattern, which progressed to frequent electrographic seizures over the left hemisphere. The interictal background EEG pattern remained grossly abnormal over the next 48 hours, showing very low background amplitudes (<10μV). Magnetic resonance imaging revealed an isolated acute left-sided thalamic infarction. This is the first description of severe global EEG suppression caused by an isolated unilateral thalamic stroke and supports the role of the thalamus as the control centre for cortical electrical activity.

1H NMR derived metabolomic profile of neonatal asphyxia in umbilical cord serum: implications for hypoxic ischemic encephalopathy

Neonatal hypoxic ischemic encephalopathy (HIE) is a severe consequence of perinatal asphyxia (PA) that can result in life-long neurological disability. Disease mechanisms, including the role and interaction of individual metabolic pathways, remain unclear. As hypoxia is an acute condition, aerobic energy metabolism is central to global metabolic pathways, and these metabolites are detectable using 1H NMR spectroscopy, we hypothesized that characterizing the NMR-derived umbilical cord serum metabolome would offer insight into the consequences of PA that lead to HIE. Fifty-nine at-risk infants were enrolled, together with 1:1 matched healthy controls, and stratified by disease severity (n=25, HIE; n=34, non-HIE PA). Eighteen of 37 reproducibly detectable metabolites were significantly altered between study groups. Acetone, 3-hydroxybutyrate, succinate, and glycerol were significantly differentially altered in severe HIE. Multivariate data analysis revealed a metabolite profile associated with both asphyxia and HIE. Multiple-linear regression modeling using 4 metabolites (3-hydroxybutyrate, glycerol, O-phosphocholine, and succinate) predicted HIE severity with an adjusted R2 of 0.4. Altered ketones suggest that systemic metabolism may play a critical role in preventing neurological injury, while altered succinate provides a possible explanation for hypoxia-inducible factor 1-α (HIF-1α) stabilization in HI injury.

Monitoring neonatal seizures

Neonatal seizures are a neurological emergency and prompt treatment is required. Seizure burden in neonates can be very high, status epilepticus a frequent occurrence, and the majority of seizures do not have any clinical correlate. Detection of neonatal seizures is only possible with continuous electroencephalogram (EEG) monitoring. EEG interpretation requires special expertise that is not available in most neonatal intensive care units (NICUs). As a result, a simplified method of EEG recording incorporating an easy-to-interpret compressed trend of the EEG output (amplitude integrated EEG) from one of the EEG output from one or two channels has emerged as a popular way to monitor neurological function in the NICU. This is not without limitations; short duration and low amplitude seizures can be missed, artefacts are problematic and may mimic seizure-like activity and only a restricted area of the brain is monitored. Continuous multichannel EEG is the gold standard for detecting seizures and monitoring response to therapy but expert interpretation of the EEG output is generally not available. Some centres have set up remote access for neurophysiologists to the cot-side EEG, but reliable interpretation is wholly dependent on the 24 h availability of experts, an expensive solution. A more practical solution for the NICU without such expertise is an automated seizure detection system. This review outlines the current state of the art regarding cot-side monitoring of neonatal seizures in the NICU.

Normative levels of Interleukin 16 in umbilical cord blood

OBJECTIVES

The need for early and accurate prediction of outcome in hypoxic-ischaemic encephalopathy (HIE) remains critical. We have previously demonstrated that Interleukin 16 (IL-16) is raised in the umbilical cord blood (UCB) of infants with moderate and severe HIE and has the potential to be developed as a predictive biomarker. Normal reference ranges for IL-16 in UCB have not been previously described. The aim of this study was to determine normative levels of IL-16 in full term neonates using UCB following uncomplicated deliveries and to examine the effect of labour on cord IL-16 values.

DESIGN AND METHODS

Full term infants were recruited as part of an ongoing birth cohort study, the Cork BASELINE Birth Cohort Study. All had UCB drawn and bio-banked at -80°C, within 3hours of birth. Samples for this experiment were chosen from this population based cohort study to represent uncomplicated pre-labour caesarean sections and spontaneous vaginal deliveries. Analysis was performed on plasma EDTA, using ELISA Quantikine® (R&D Systems, Europe).

RESULTS

Samples were analysed from 48 infants with two modes of delivery; spontaneous vaginal delivery (n=12 male, n=12 female) and elective caesarean section (n=12 male, n=12 female). The range of all samples was normally distributed between 87.0 and 114.6pg/ml. Overall mean (SD) for IL-16 was 102.9 (21.5) pg/ml. Levels were not affected by spontaneous vaginal delivery or gender.

CONCLUSION

For the first time we have described the expected range of cord plasma IL-16 levels in healthy term infants following pre-labour and post-labour delivery.

Association of nucleated red blood cells and severity of encephalopathy in normothermic and hypothermic infants

AIM

To determine whether hypothermia alters the discriminative ability of postnatal nucleated red blood cells (NRBCs) to distinguish between mild and moderate/severely encephalopathic infants.

METHODS

A prospective cohort study recruited full-term neonates with hypoxic ischaemic encephalopathy (HIE) from 2003 to 2012 (prehypothermic and hypothermic eras). The NRBC count was analysed in the first 24 h in all infants and compared between normothermic and hypothermic cohorts. The severity of encephalopathy was categorized using both clinical Sarnat score and continuous multichannel EEG.

RESULTS

Eighty-six infants with HIE were included: in the normothermic group, 19 were clinically mild, 24 moderate/severe; in the hypothermic group, 22 were mild, 21 moderate/severe encephalopathy. NRBC count discriminated between mild and moderate/severe Sarnat scores in the normothermic group (p = 0.03) but not in the hypothermic group (p = 0.9). This change was due to a decrease in NRBCs among moderately encephalopathic infants in the hypothermic cohort.

CONCLUSION

Postnatal NRBCs distinguished between mild and moderate/severe encephalopathy in normothermic infants but not in infants undergoing therapeutic hypothermia. We advise caution when using postnatal blood samples to study diagnostic biomarkers for HIE without first analysing the potential impact of hypothermia upon these markers.

The metabolomic profile of umbilical cord blood in neonatal hypoxic ischaemic encephalopathy

Background

Hypoxic ischaemic encephalopathy (HIE) in newborns can cause significant long-term neurological disability. The insult is a complex injury characterised by energy failure and disruption of cellular homeostasis, leading to mitochondrial damage. The importance of individual metabolic pathways, and their interaction in the disease process is not fully understood. The aim of this study was to describe and quantify the metabolomic profile of umbilical cord blood samples in a carefully defined population of full-term infants with HIE.

Methods and Findings

The injury severity was defined using both the modified Sarnat score and continuous multichannel electroencephalogram. Using these classification systems, our population was divided into those with confirmed HIE (n = 31), asphyxiated infants without encephalopathy (n = 40) and matched controls (n = 71). All had umbilical cord blood drawn and biobanked at −80°C within 3 hours of delivery. A combined direct injection and LC-MS/MS assay (AbsolutIDQ p180 kit, Biocrates Life Sciences AG, Innsbruck, Austria) was used for the metabolomic analyses of the samples. Targeted metabolomic analysis showed a significant alteration between study groups in 29 metabolites from 3 distinct classes (Amino Acids, Acylcarnitines, and Glycerophospholipids). 9 of these metabolites were only significantly altered between neonates with Hypoxic ischaemic encephalopathy and matched controls, while 14 were significantly altered in both study groups. Multivariate Discriminant Analysis models developed showed clear multifactorial metabolite associations with both asphyxia and HIE. A logistic regression model using 5 metabolites clearly delineates severity of asphyxia and classifies HIE infants with AUC = 0.92. These data describe wide-spread disruption to not only energy pathways, but also nitrogen and lipid metabolism in both asphyxia and HIE.

Conclusion

This study shows that a multi-platform targeted approach to metabolomic analyses using accurately phenotyped and meticulously biobanked samples provides insight into the pathogenesis of perinatal asphyxia. It highlights the potential for metabolomic technology to develop a diagnostic test for HIE.

An automated system for grading EEG abnormality in term neonates with hypoxic-ischaemic encephalopathy

Automated analysis of the neonatal EEG has the potential to assist clinical decision making for neonates with hypoxic-ischaemic encephalopathy. This paper proposes a method of automatically grading the degree of abnormality in an hour long epoch of neonatal EEG. The automated grading system (AGS) was based on a multi-class linear classifier grading of short-term epochs of EEG which were converted into a long-term grading of EEG using a majority vote operation. The features used in the AGS were summary measurements of two sub-signals extracted from a quadratic time-frequency distribution: the amplitude modulation and instantaneous frequency. These sub-signals were based on a model of EEG as a multiplication of a coloured random process with a slowly varying pseudo-periodic waveform and may be related to macroscopic neurophysiological function. The 4 grade AGS had a classification accuracy of 83% compared to human annotation of the EEG (level of agreement, κ = 0.76). Features estimated on the developed sub-signals proved more effective at grading the EEG than measures based solely on the EEG and the incorporation of additional sub-grades based on EEG states into the AGS also improved performance.

Selection of student-selected component [SSCs] modules across the medical undergraduate curriculum: relationship with motivational factors

Student-selected components (SSCs) encourage the following within the undergraduate medical curriculum: greater exploration of core curriculum topics; exploration of non-core subjects/experiences; research and self-directed learning; and personal and professional development opportunities. This study examined the motivational factors which influence SSC choice to assess (a) SSC selection patterns across each year of the curriculum (direct and graduate entry) and (b) motivation underlying SSC selection across the curriculum. During SSC registration at University College Cork, all medical undergraduates (years 1-3, graduate-entry medicine) were required to select an SSC and provide a written justification for their selection. Five primary motivational factors were identified: correction of perceived deficits; genuine interest in subject and wish to study in more depth; career strategy; exam strategy; and taking a chance. A complex pattern of relationships emerged in relation to matching of motivational factors with SSC categories, e.g. selection of research skills SSCs was strongly associated with the 'career strategy' motivation. Significant differences were observed across curriculum years, as well as between direct-entry versus graduate-entry undergraduates, with respect to SSC selections and underlying motivation. This study provides insight into changing patterns of SSC selection in medicine, as well as accompanying motivational factors, across the undergraduate years.

Cooling and seizure burden in term neonates: an observational study

OBJECTIVE

To investigate any possible effect of cooling on seizure burden, the authors quantified the recorded electrographic seizure burden based on multichannel video-EEG recordings in term neonates with hypoxic-ischaemic encephalopathy (HIE) who received cooling and in those who did not.

STUDY DESIGN

Retrospective observational study.

PATIENTS

Neonates >37 weeks gestation born between 2003 and 2010 in two hospitals.

METHODS

Off-line analysis of prolonged continuous multichannel video-EEG recordings was performed independently by two experienced encephalographers. Comparison between the recorded electrographic seizure burden in non-cooled and cooled neonates was assessed. Data were treated as non-parametric and expressed as medians with interquartile ranges (IQR).

RESULTS

One hundred and seven neonates with HIE underwent prolonged continuous multichannel EEG monitoring. Thirty-seven neonates had electrographic seizures, of whom 31 had EEG recordings that were suitable for the analysis (16 non-cooled and 15 cooled). Compared with non-cooled neonates, multichannel EEG monitoring commenced at an earlier postnatal age in cooled neonates (6 (3-9) vs 15 (5-20) h)and continued for longer (88 (75-101) vs 55 (41-60) h). Despite this increased opportunity to capture seizures in cooled neonates, the recorded electrographic seizure burden in the cooled group was significantly lower than in the non-cooled group (60 (39-224) vs 203 (141-406) min). Further exploratory analysis showed that the recorded electrographic seizure burden was only significantly reduced in cooled neonates with moderate HIE (49 (26-89) vs 162 (97-262) min).

CONCLUSIONS

A decreased seizure burden was seen in neonates with moderate HIE who received cooling. This finding may explain some of the therapeutic benefits of cooling seen in term neonates with moderate HIE.

Long-range temporal correlations in the EEG bursts of human preterm babies

The electrical activity in the very early human preterm brain, as recorded by scalp EEG, is mostly discontinuous and has bursts of high-frequency oscillatory activity nested within slow-wave depolarisations of high amplitude. The temporal organisation of the occurrence of these EEG bursts has not been previously investigated. We analysed the distribution of the EEG bursts in 11 very preterm (23-30 weeks gestational age) human babies through two estimates of the Hurst exponent. We found long-range temporal correlations (LRTCs) in the occurrence of these EEG bursts demonstrating that even in the very immature human brain, when the cerebral cortical structure is far from fully developed, there is non-trivial temporal structuring of electrical activity.

Monitoring of seizures in the newborn

Neonatal seizures are a distinct and not uncommon sign of neurological disease in the newborn, most often occurring in association with hypoxic-ischaemic encephalopathy at term. The diagnosis and monitoring of seizures in the newborn is a considerable challenge, with many suspected clinical seizures having no electrographic correlates, while many electrographic seizures have no clinical correlate. Continuous video-EEG is the gold standard for seizure monitoring, but few centres have the resources or expertise required. Amplitude-integrated EEG can be a helpful monitoring tool in experienced hands, but has potential for error when used by inexperienced staff. Automated seizure detection algorithms show much promise and some cotside systems are already available. The efficiency and accuracy of these systems is likely to improve.

Instantaneous measure of EEG channel importance for improved patient-adaptive neonatal seizure detection

A measure of bipolar channel importance is proposed for EEG-based detection of neonatal seizures. The channel weights are computed based on the integrated synchrony of classifier probabilistic outputs for the channels which share a common electrode. These estimated time-varying weights are introduced within a Bayesian probabilistic framework to provide a channel specific and, thus, adaptive seizure classification scheme. Validation results on a clinical dataset of neonatal seizures confirm the utility of the proposed channel weighting for the two patient-independent seizure detectors recently developed by this research group: one based on support vector machines (SVMs) and the other on Gaussian mixture models (GMMs). By exploiting the channel weighting, the receiver operating characteristic (ROC) area can be significantly increased for the most difficult patients, with the average ROC area across 17 patients increased by 22% (relative) for the SVM and by 15% (relative) for the GMM-based detector, respectively. It is shown that the system developed here outperforms the recent published studies in this area.

The use of conventional EEG for the assessment of hypoxic ischaemic encephalopathy in the newborn: a review

Neonatal hypoxic ischaemic encephalopathy continues to be one of the leading causes of morbidity and mortality among neonates around the globe. With the advent of therapeutic hypothermia, the need to accurately classify the severity of injury in the early neonatal period is of great importance. As clinical measures cannot always accurately estimate the severity early enough for treatment to be initiated, clinicians have become more dependent on conventional and amplitude integrated EEG. Despite this, there is currently no single agreed classification scheme for the neonatal EEG in hypoxic ischaemic encephalopathy. In this review we discuss classification schemes of neonatal background EEG, published over the past 35 years, highlighting the urgent need for a universal visual analysis scheme.

Nucleated red blood cells and early EEG: predicting Sarnat stage and two year outcome

AIMS

Hypoxic Ischaemic Encephalopathy (HIE) causes characteristic changes of the electroencephalogram (EEG), and a raised Nucleated Red Blood Cell (NRBC) count compared to controls. We wished to examine whether combining these markers could improve their ability to predict HIE severity in the first 24h.

METHODS

Term infants with HIE were recruited. NRBC count and continuous multi-channel EEG were recorded within the first 24h. Neurological assessment was carried out at 24 months. A control population with NRBC counts in the first 24h was recruited.

RESULTS

44 infants with HIE and 43 control infants were recruited. Of the HIE population 39 completed a 2 year follow-up. The median NRBC count differed significantly between the controls and those with HIE (3/100 WBC [range of 0-11] vs 12.3/100 WBC [0-240]) (p<0.001). Within the HIE population the median NRBC count was significantly greater in infants with moderate/severe HIE than mild (16/100 WBC [range of 0-240] vs 8/100 WBC [1-23]) (p=0.016), and among infants with abnormal outcome compared to normal (21.3/100 WBC [1-239.8] vs 8.3/100 WBC [0-50])(p=0.03). The predictive ability of EEG changed with time post-delivery, therefore results are given at both 12 and 24h of age. At both time points the combined marker had a stronger correlation than EEG alone; with HIE severity (12h: r=0.661 vs r=0.622), (24h: r=0.645 vs r=0.598), and with outcome at 2 years (12h: r=0.756 vs r=0.652), (24h: r=0.802 vs r=0.746).

CONCLUSION

Combining early EEG and NRBC count to predict HIE severity and neurological outcome, improved the predictive ability of either in isolation.

Early blood glucose profile and neurodevelopmental outcome at two years in neonatal hypoxic-ischaemic encephalopathy

Background

To examine the blood glucose profile and the relationship between blood glucose levels and neurodevelopmental outcome in term infants with hypoxic-ischaemic encephalopathy.

Methods

Blood glucose values within 72 hours of birth were collected from 52 term infants with hypoxic-ischaemic encephalopathy. Hypoglycaemia [< 46.8 mg/dL (2.6 mmol/L)] and hyperglycaemia [> 150 mg/dL (8.3 mmol/L)] were correlated to neurodevelopmental outcome at 24 months of age.

Results

Four fifths of the 468 blood samples were in the normoglycaemic range (392/468:83.8%). Of the remaining 76 samples, 51.3% were in the hypoglycaemic range and (48.7%) were hyperglycaemic. A quarter of the hypoglycaemic samples (28.2%:11/39) and a third of the hyperglycaemic samples (32.4%:12/37) were recorded within the first 30 minutes of life. Mean (SD) blood glucose values did not differ between infants with normal and abnormal outcomes [4.89(2.28) mmol/L and 5.02(2.35) mmol/L, p value = 0.15] respectively. In term infants with hypoxic-ischaemic encephalopathy, early hypoglycaemia (between 0-6 hours of life) was associated with adverse outcome at 24 months of age [OR = 5.8, CI = 1.04-32)]. On multivariate analysis to adjust for grade of HIE this association was not statistically significant. Late hypoglycaemia (6-72 hours of life) was not associated with abnormal outcome [OR = 0.22, CI (0.04-1.14)]. The occurrence of hyperglycaemia was not associated with adverse outcome.

Conclusion

During the first 72 hours of life, blood glucose profile in infants with hypoxic-ischaemic encephalopathy varies widely despite a management protocol. Early hypoglycaemia (0-6 hours of life) was associated with severe HIE, and thereby; adverse outcome.

Early continuous video electroencephalography in neonatal stroke

Perinatal stroke is the second most common cause of neonatal seizures, and can result in long-term neurological impairment. Diagnosis is often delayed until after seizure onset, owing to the subtle nature of associated signs. We report the early electroencephalographic (EEG) findings in a female infant with a perinatal infarction, born at 41 weeks 2 days and weighing 3.42 kg. Before the onset of seizures, the EEG from 3 hours after delivery demonstrated occasional focal sharp waves over the affected region. After electroclinical seizures, focal sharp waves became more frequent, complex, and of higher amplitude, particularly in 'quiet sleep'. In 'active sleep', sharp waves often disappeared. Diffusion-weighted imaging confirmed the infarct, demonstrating left frontal and parietal diffusion restriction. At 9 months, the infant has had no further seizures, and neurological examination is normal. To our knowledge, this report is the first to describe the EEG findings in perinatal stroke before seizures, and highlights the evolution of characteristic background EEG features.

Presence of both parents during consent process in non-therapeutic neonatal research increases positive response

AIM

To investigate factors that influenced parental consent/non-consent in a non-therapeutic electroencephalogram (EEG) study in healthy newborns.

METHODS

Parents of healthy newborns were approached to participate in a neonatal EEG study within 36 h of birth. The rationale and risks/benefits of the study were explained. Any concerns were discussed, and detailed information about the EEG study was provided in the consent form. In the case of refusing/withdrawing consent, an informal interview was used to investigate the reasons, which were subsequently analysed and grouped according to the four principles of the consent process.

RESULTS

A total of 123 parents were included in the study. Parental consent was obtained in 72/123 (59%) cases, 10/123 (8%) parents subsequently withdrew their consent and 41/123 (33%) parents refused to participate in the study. Consent was more likely if both parents were present (p < 0.0001). When the mothers were approached alone, obtaining consent was significantly more difficult within the first 6 hours of delivery, compared to a later approach (37% vs. 67% respectively; p = 0.009). Refusals were classified into issues of voluntariness (7%), informed choice (10%), understanding (54%) and competence (29%).

CONCLUSION

Parents of healthy newborns demonstrated a positive attitude towards non-therapeutic neonatal research with maximal consent occurring when both parents were present. Parental perception of harm was the main reason for declining consent.

Undergraduate medical research: the student perspective

BACKGROUND

Research training is essential in a modern undergraduate medical curriculum. Our evaluation aimed to (a) gauge students' awareness of research activities, (b) compare students' perceptions of their transferable and research-specific skills competencies, (c) determine students' motivation for research and (d) obtain students' personal views on doing research.

METHODS

Undergraduate medical students (N = 317) completed a research skills questionnaire developed by the Centre for Excellence in Teaching and Learning in Applied Undergraduate Research Skills (CETL-AURS) at Reading University. The questionnaire assessed students' transferable skills, research-specific skills (e.g., study design, data collection and data analysis), research experience and attitude and motivation towards doing research.

RESULTS

The majority of students are motivated to pursue research. Graduate entrants and male students appear to be the most confident regarding their research skills competencies. Although all students recognise the role of research in medical practice, many are unaware of the medical research activities or successes within their university. Of those who report no interest in a career incorporating research, a common perception was that researchers are isolated from patients and clinical practice.

DISCUSSION

Students have a narrow definition of research and what it entails. An explanation for why research competence does not align more closely with research motivation is derived from students' lack of understanding of the concept of translational research, as well as a lack of awareness of the research activity being undertaken by their teachers and mentors. We plan to address this with specific research awareness initiatives.

Performance assessment for EEG-based neonatal seizure detectors

Objective

This study discusses an appropriate framework to measure system performance for the task of neonatal seizure detection using EEG. The framework is used to present an extended overview of a multi-channel patient-independent neonatal seizure detection system based on the Support Vector Machine (SVM) classifier.

Methods

The appropriate framework for performance assessment of neonatal seizure detectors is discussed in terms of metrics, experimental setups, and testing protocols. The neonatal seizure detection system is evaluated in this framework. Several epoch-based and event-based metrics are calculated and curves of performance are reported. A new metric to measure the average duration of a false detection is proposed to accompany the event-based metrics. A machine learning algorithm (SVM) is used as a classifier to discriminate between seizure and non-seizure EEG epochs. Two post-processing steps proposed to increase temporal precision and robustness of the system are investigated and their influence on various metrics is shown. The resulting system is validated on a large clinical dataset of 267 h.

Results

In this paper, it is shown how a complete set of metrics and a specific testing protocol are necessary to extensively describe neonatal seizure detection systems, objectively assess their performance and enable comparison with existing alternatives. The developed system currently represents the best published performance to date with an ROC area of 96.3%. The sensitivity and specificity were ∼90% at the equal error rate point. The system was able to achieve an average good detection rate of ∼89% at a cost of 1 false detection per hour with an average false detection duration of 2.7 min.

Conclusions

It is shown that to accurately assess the performance of EEG-based neonatal seizure detectors and to facilitate comparison with existing alternatives, several metrics should be reported and a specific testing protocol should be followed. It is also shown that reporting only event-based metrics can be misleading as they do not always reflect the true performance of the system.

Significance

This is the first study to present a thorough method for performance assessment of EEG-based seizure detection systems. The evaluated SVM-based seizure detection system can greatly assist clinical staff, in a neonatal intensive care unit, to interpret the EEG.

Gaussian mixture models for classification of neonatal seizures using EEG

A real-time neonatal seizure detection system is proposed based on a Gaussian mixture model classifier. The system includes feature transformation techniques and classifier output postprocessing. The detector was evaluated on a database of 20 patients with 330 h of recordings. A detailed analysis of the choice of parameters for the detector is provided. A mean good detection rate of 79% was obtained with only 0.5 false detections per hour. A thorough review of all misclassified events was performed, from which a number of patterns causing false detections were identified.

The predictive value of early neurological examination in neonatal hypoxic-ischaemic encephalopathy and neurodevelopmental outcome at 24 months

AIM

The clinical and electrographic signs of hypoxic-ischaemic encephalopathy (HIE) evolve over the first days of life. We examined the evolution of neurological signs over the first 3 days of life, and determined whether serial administration of the Amiel-Tison Neurological Assessment at Term (ATNAT) would predict neurodevelopmental outcome at 24 months.

METHOD

Term (>37 wks' gestation) neonates born with suspected HIE between May 2003 and May 2005 in a Cork maternity unit were recruited prospectively. Modified Sarnat grading was assigned. The ATNAT was administered on days 1, 2, and 3 of life and a discharge neurological examination. Time to oral feeding and demographic variables were recorded. Developmental status was assessed using the revised Griffiths Mental Development Scales at 6, 12, and 24 months.

RESULTS

Fifty-seven infants were recruited, with 51 (31 males, 20 females) included for follow-up. Neurological examination evolved and normalized over the first 3 days of life in many cases. At 24 months, 21 children had an adverse outcome, including six deaths. Examination at all time points correlated significantly with neurological outcome at 24 months. The best correlations were found to be (1) neurological examination at discharge (r=0.65, p<0.001), (2) Sarnat grading (r=0.64, p<0.001), and (3) ATNAT on day 3 (r=0.46, p<0.001). The best predictive value was seen with neurological examination at discharge (positive and negative predictive values of 86% and 72% respectively).

INTERPRETATION

Persistence of abnormal neurological signs correlates significantly with adverse outcome. The later a neonatal neurological examination was performed, the better its predictive ability.

Predicting the neurodevelopmental outcome in newborns with hypoxic-ischaemic injury

The prediction of outcome in newborns with hypoxic ischemic encephalopathy (HIE) is a problematic task. Here, the ability of a combination of clinical, heart rate and EEG measures to predict outcome at 2 years is investigated. One hour of EEG and ECG recordings were obtained from newborns 24 hours after birth. Each newborn was reassessed at 24 months to investigate their neurodevelopmental outcome. From the EEG and ECG recordings, a set of 12 features was extracted. To classify each baby's outcome this data, along with clinical information was fed to a support vector machine. On a per patient basis an ROC area of 0.768 was achieved with 73.68% of newborns being assigned the correct outcome. Overall, this system presents a promising step towards the use of multimodal data for the prediction of neurodevelopmental outcome in newborns with HIE.

Early EEG findings in hypoxic-ischemic encephalopathy predict outcomes at 2 years

OBJECTIVE

We examined the evolution of electroencephalographic (EEG) changes after hypoxic injury.

METHODS

Continuous, multichannel, video-EEG was recorded for term infants with hypoxic-ischemic encephalopathy, from <6 hours to 72 hours after delivery. One-hour segments at 6, 12, 24, and 48 hours of age of the EEG were analyzed visually, and neurologic outcome was assessed at 24 months.

RESULTS

Forty-four infants completed neurodevelopmental follow-up. Of those, 20 (45%) had abnormal outcomes. The EEG grade assigned correlated significantly with outcome. EEG abnormalities improved with time, with the worst EEG grade seen on the earliest recording in all cases. The best predictive ability was seen at 6 hours of age (area under the receiver operator characteristic curve: 0.958 [95% confidence interval: 0.88-1.04]; P = .000). Normal/mildly abnormal EEG results at 6, 12, or 24 hours had 100% positive predictive values for normal outcomes and negative predictive values of 67% to 76%. By 48 hours, many of the EEG findings had improved significantly. This led to the positive predictive value of abnormal EEG results being greater at 48 hours (93%), with a concurrent negative predictive value of 71%. EEG features that were associated with abnormal outcomes were background amplitude of <30 microV, interburst interval of >30 seconds, electrographic seizures, and absence of sleep-wake cycling at 48 hours.

CONCLUSIONS

Early EEG is a reliable predictor of outcome in HIE. A normal or mildly abnormal EEG results within 6 hours after birth were associated with normal neurodevelopmental outcomes at 24 months.

Characterisation of heart rate changes and their correlation with EEG during neonatal seizures

The effect of seizures on instantaneous HR (iHR) in 12 neonates is investigated here. HR can be readily extracted from the ECG and can be employed as an additional signal in seizure detection algorithms. The change in instantaneous HR and its correlation with the change in RMS EEG amplitude were examined. Two methods were employed to classify significant iHR changes. Significant correlation (p 0.05) during seizure was observed in 100% of patients (83.33% of seizures). Overall, significant iHR changes (classified by either method) were found in 83% of patients (50% of seizures). It was found that a markedly higher iHR was observed in patients whose seizures were not classified as having significant iHR changes.

Persistent lactic acidosis in neonatal hypoxic-ischaemic encephalopathy correlates with EEG grade and electrographic seizure burden

BACKGROUND

Predicting at birth which infants with perinatal hypoxic-ischaemic injury will progress to significant encephalopathy remains a challenge.

OBJECTIVE

To determine whether lactic acidosis at birth in asphyxiated neonates could predict the grade of EEG encephalopathy by examining the relationship between time taken for the normalisation of lactate, severity of encephalopathy and seizure burden.

METHODS

Continuous early video-EEG monitoring was performed in babies at risk for hypoxic-ischaemic encephalopathy. Encephalopathy was graded from the EEG data. Total seizure burden (seconds) was calculated for each baby. Initial blood gas measurements of pH, base deficit and lactate were taken within 30 minutes of delivery. Time to normal serum lactate was determined in hours from birth for each infant.

RESULTS

All 50 term infants had raised initial serum lactate (median (lower, upper quartiles) 11.7 (10.2, 14.9)). There were no significant differences between the initial serum lactate, pH and base deficit in infants with normal/mildly abnormal (n = 24), moderately abnormal (n = 14), severely abnormal (n = 5) and inactive EEGs (n = 7). Time to normal lactate varied significantly with EEG grade (median (lower, upper quartile) 6.0 (4.1, 9.5) for mild/normal EEG, 13.5 (6.8, 23.5) moderate EEG, 41.5 (30.0, 55.5) severe group, 12.0 (8.1, 21.5) inactive group; p<0.001). Time to normal lactate correlated significantly with EEG seizure burden (seconds; R = 0.446, p = 0.002). Mean (SD) time to normal lactate was 10.0 (7.2) hours in infants who did not have seizures and 27.3 (19.0) hours in the 13 infants with electrographic seizures (p = 0.002).

CONCLUSIONS

Serum lactate levels in the first 30 minutes of life do not predict the severity of the ensuing encephalopathy. In contrast, sustained lactic acidosis is associated with severe encephalopathy on EEG and correlates with seizure burden.

Defining the gap between electrographic seizure burden, clinical expression and staff recognition of neonatal seizures

BACKGROUND

Neonatal seizures are often subclinical, making accurate diagnosis difficult.

OBJECTIVE

To describe the clinical manifestations of electrographic seizures recorded on continuous video-EEG, and to compare this description with the recognition of clinical seizures by experienced neonatal staff.

METHODS

Term infants, at risk of seizures, were monitored by continuous 12-channel video-EEG from <6 hours of birth for up to 72 hours. All clinical seizures were recorded by experienced neonatal staff on individual seizure charts. Video-EEG recordings were subsequently analysed. The number, duration and clinical expression of electrographic seizures were calculated (in seconds), and compared with the seizures clinically suspected by the neonatal staff.

RESULTS

Of 51 infants enrolled, nine had electrographic seizures. A further three had clinically suspected seizures, without associated electrographic abnormality. Of the total 526 electrographic seizures, 179 (34%) had clinical manifestations evident on the simultaneous video recording. The clinical seizure activity corresponded to 18.8% of the total electrographic seizure burden. Overdiagnosis also occurred frequently. Of the 177 clinically suspected seizure episodes documented by staff, 48 (27%) had corresponding electrographic evidence of seizure activity Thus, only 9% (48/526) of electrographic seizures were accompanied by clinical manifestations, which were identified and documented by neonatal staff.

CONCLUSION

Only one-third of neonatal EEG seizures displays clinical signs on simultaneous video recordings. Moreover, two-thirds of these clinical manifestations are unrecognised, or misinterpreted by experienced neonatal staff. In the recognition and management of neonatal seizures clinical diagnosis alone is not enough.