Characterisation of neonatal seizures and their treatment using continuous EEG monitoring: a multicentre experience

OBJECTIVE

The aim of this multicentre study was to describe detailed characteristics of electrographic seizures in a cohort of neonates monitored with multichannel continuous electroencephalography (cEEG) in 6 European centres.

METHODS

Neonates of at least 36 weeks of gestation who required cEEG monitoring for clinical concerns were eligible, and were enrolled prospectively over 2 years from June 2013. Additional retrospective data were available from two centres for January 2011 to February 2014. Clinical data and EEGs were reviewed by expert neurophysiologists through a central server.

RESULTS

Of 214 neonates who had recordings suitable for analysis, EEG seizures were confirmed in 75 (35%). The most common cause was hypoxic-ischaemic encephalopathy (44/75, 59%), followed by metabolic/genetic disorders (16/75, 21%) and stroke (10/75, 13%). The median number of seizures was 24 (IQR 9-51), and the median maximum hourly seizure burden in minutes per hour (MSB) was 21 min (IQR 11-32), with 21 (28%) having status epilepticus defined as MSB>30 min/hour. MSB developed later in neonates with a metabolic/genetic disorder. Over half (112/214, 52%) of the neonates were given at least one antiepileptic drug (AED) and both overtreatment and undertreatment was evident. When EEG monitoring was ongoing, 27 neonates (19%) with no electrographic seizures received AEDs. Fourteen neonates (19%) who did have electrographic seizures during cEEG monitoring did not receive an AED.

CONCLUSIONS

Our results show that even with access to cEEG monitoring, neonatal seizures are frequent, difficult to recognise and difficult to treat.

OBERSERVATION STUDY NUMBER

NCT02160171.

EEG for the assessment of neurological function in newborn infants immediately after birth

OBJECTIVE

To assess the neurological function of newborn infants in the first minutes after birth using EEG.

DESIGN AND PATIENTS

We obtained electroencephalography (EEG) recordings in term infants following elective caesarean section. After delivery, disposable EEG electrodes were attached to the infants' scalp over the frontal and central regions bilaterally and EEG was recorded for 10 min. Both visual and quantitative measures were used to analyse the EEGs.

SETTING

The operative delivery theatre of Cork University Maternity Hospital, Ireland.

RESULTS

Forty-nine infants had EEG recordings over the frontal and central regions. The median (IQR) age at time of initial EEG recording was 3.0 (2.5-3.8) min. While movement artefact contaminated parts of many recordings, good-quality EEG, with mixed-frequency activity with a range of 25-50 μV, was observed in all infants. The majority of EEG spectral power was within the delta band: the median (IQR) relative delta power was 87.8% (83.7%-90%). Almost all (95%) spectral power was below a median (IQR) of 7.56 Hz (6.17-9.76 Hz).

CONCLUSIONS

EEG recording is very feasible in the immediate newborn period. This study provides valuable objective information about neurological function during this transitional period.

Core temperature after birth in babies with neonatal encephalopathy in a sub-Saharan African hospital setting

KEY POINTS

Therapeutic hypothermia (HT) to 33.0-34.0°C for 72 h provides optimal therapy for infants with neonatal encephalopathy (NE) in high-resource settings. HT is not universally implemented in low- and middle-income countries as a result of both limited resources and evidence. Facilitated passive cooling, comprising infants being allowed to passively lower their body temperature in the days after birth, is an emerging practice in some West African neonatal units. In this observational study, we demonstrate that infants undergoing facilitated passive cooling in a neonatal unit in Accra, Ghana, achieve temperatures within the HT target range ∼20% of the 72 h. Depth of HT fluctuates and can be excessive, as well as not maintained, especially after 24 h. Sustained and deeper passive cooling was evident for severe NE and for those that died. It is important to prevent excessive cooling, to understand that severe NE babies cool more and to be aware of facilitated passive cooling with respect to the design of clinical trials in low- and mid-resource settings.

ABSTRACT

Neonatal encephalopathy (NE) is a significant worldwide problem with the greatest burden in sub-Saharan Africa. Therapeutic hypothermia (HT), comprising the standard of care for infants with moderate-to-severe NE in settings with sophisticated intensive care, is not available to infants in many sub-Saharan African countries, including Ghana. We prospectively assessed the temperature response in relation to outcome in the 80 h after birth in a cohort of babies with NE undergoing 'facilitated passive cooling' at Korle Bu Teaching Hospital, Accra, Ghana. We hypothesized that NE infants demonstrate passive cooling. Thirteen infants (69% male) ≥36 weeks with moderate-to-severe NE were enrolled. Ambient mean ± SD temperature was 28.3 ± 0.7°C. Infant core temperature was 34.2 ± 1.2°C over the first 24 h and 35.0 ± 1.0°C over 80 h. Nadir mean temperature occurred at 15 h. Temperatures were within target range for HT with respect to 18 ± 14% of measurements within the first 72 h. Axillary temperature was 0.5 ± 0.2°C below core. Three infants died before discharge. Core temperature over 80 h for surviving infants was 35.3 ± 0.9°C and 33.96 ± 0.7°C for those that died (P = 0.043). Temperature profile negatively correlated with Thompson NE score on day 4 (r2  = 0.66): infants with a Thompson score of 0-6 had higher temperatures than those with a score of 7-15 (P = 0.021) and a score of 16+/deceased (P = 0.007). More severe NE was associated with lower core temperatures. Passive cooling is a physiological response after hypoxia-ischaemia; however, the potential neuroprotective effect of facilitated passive cooling is unknown. An awareness of facilitated passive cooling in babies with NE is important for the design of clinical trials of neuroprotection in low and mid resource settings.

Suitability of an inter-burst detection method for grading hypoxic-ischemic encephalopathy in newborn EEG

Electroencephalography (EEG) is an important clinical tool for grading injury caused by lack of oxygen or blood to the brain during birth. Characteristics of low-voltage waveforms, known as inter-bursts, are related to different grades of injury. This study assesses the suitability of an existing inter-burst detection method, developed from preterm infants born <; 30 weeks of gestational age, to detect inter-bursts in term infants. Different features from the temporal organisation of the inter-bursts are combined using a multi-layer perceptron (MLP) machine learning algorithm to classify four grades of injury in the EEG. We find that the best performing feature, percentage of inter-bursts, has an accuracy of 59.3%. Combining this with the maximum duration of inter-bursts in the MLP produces a testing accuracy of 77.8%, with similar performance to existing multi-feature methods. These results validate the use of the preterm detection method in term EEG and show how simple measures of the inter-burst interval can be used to classify different grades of injury.

Parental opinion of consent in neonatal research

BACKGROUND

Neonatal research, particularly neonatal emergency research is a challenging area, notably in relation to obtaining valid prospective informed consent. The aim of this study is to determine parental perceptions of the consent process involved in performing research in newborn care, to explore methods used to obtain consent and their acceptability to parents.

METHODS

A parental questionnaire was developed that examined attitudes towards research and hypothetical research studies, in which the acceptability of various methods of consent was examined (informed, waived, deferred). These research scenarios were of varying time sensitivity and perceived risk level. The study setting was an Irish maternity hospital.

RESULTS

There were 600 responses to the questionnaire. In 93% of cases, parents felt that their involvement in the consent process was essential. In emergency situations, 52% felt full prospective informed consent was necessary; however, almost 28% of parents would feel pressure to consent. Most (75%) parents would prefer to be approached to discuss neonatal research studies antenatally, irrespective of study type and 40% of parents felt that neonates involved in research studies received overall better care. Acceptability of deferred consent was greater than waived, and was highest for the more emergency-based scenarios presented.

DISCUSSION

Parents feel that they should play a central role in research involving their children. There were differences in the acceptability of various consent methods with strongest agreement for informed consent and lowest agreement for waived consent. Parents were more willing to accede to deferred consent in the cardiopulmonary resuscitation scenario study. These findings provide useful insights to consent strategies in future newborn research studies.

Clamping the Umbilical Cord in Premature Deliveries (CUPiD): Neuromonitoring in the Immediate Newborn Period in a Randomized, Controlled Trial of Preterm Infants Born at <32 Weeks of Gestation

OBJECTIVE

To compare cerebral activity and oxygenation in preterm infants (<32 weeks of gestation) randomized to different cord clamping strategies.

STUDY DESIGN

Preterm infants born at <32 weeks of gestation were randomized to immediate cord clamping, umbilical cord milking (cord stripped 3 times), or delayed cord clamping for 60 seconds with bedside resuscitation. All infants underwent electroencephalogram (EEG) and cerebral near infrared spectroscopy for the first 72 hours after birth. Neonatal primary outcome measures were quantitative measures of the EEG (17 features) and near infrared spectroscopy over 1-hour time frames at 6 and 12 hours of life.

RESULTS

Forty-five infants were recruited during the study period. Twelve infants (27%) were randomized to immediate cord clamping, 19 (42%) to umbilical cord milking, and 14 (31%) to delayed cord clamping with bedside resuscitation. There were no significant differences between groups for measures of EEG activity or cerebral near infrared spectroscopy. Three of the 45 infants (6.7%) were diagnosed with severe IVH (2 in the immediate cord clamping group, 1 in the umbilical cord milking group; P = .35).

CONCLUSIONS

There were no differences in cerebral EEG activity and cerebral oxygenation values between cord management strategies at 6 and 12 hours.

TRIAL REGISTRATION

ISRCTN92719670.

Temporal evolution of quantitative EEG within 3 days of birth in early preterm infants

For the premature newborn, little is known about changes in brain activity during transition to extra-uterine life. We aim to quantify these changes in relation to the longer-term maturation of the developing brain. We analysed EEG for up to 72 hours after birth from 28 infants born <32 weeks of gestation. These infants had favourable neurodevelopment at 2 years of age and were without significant neurological compromise at time of EEG monitoring. Quantitative EEG was generated using features representing EEG power, discontinuity, spectral distribution, and inter-hemispheric connectivity. We found rapid changes in cortical activity over the 3 days distinct from slower changes associated with gestational age: for many features, evolution over 1 day after birth is equivalent to approximately 1 to 2.5 weeks of maturation. Considerable changes in the EEG immediately after birth implies that postnatal adaption significantly influences cerebral activity for early preterm infants. Postnatal age, in addition to gestational age, should be considered when analysing preterm EEG within the first few days after birth.

Quantitative Preterm EEG Analysis: The Need for Caution in Using Modern Data Science Techniques

Hemodynamic changes during neonatal transition increase the vulnerability of the preterm brain to injury. Real-time monitoring of brain function during this period would help identify the immediate impact of these changes on the brain. Neonatal EEG provides detailed real-time information about newborn brain function but can be difficult to interpret for non-experts; preterm neonatal EEG poses even greater challenges. An objective quantitative measure of preterm brain health would be invaluable during neonatal transition to help guide supportive care and ultimately protect the brain. Appropriate quantitative measures of preterm EEG must be calculated and care needs to be taken when applying the many techniques available for this task in the era of modern data science. This review provides valuable information about the factors that influence quantitative EEG analysis and describes the common pitfalls. Careful feature selection is required and attention must be paid to behavioral state given the variations encountered in newborn EEG during different states. Finally, the detrimental influence of artifacts on quantitative EEG analysis is illustrated.

Untargeted metabolomic analysis and pathway discovery in perinatal asphyxia and hypoxic-ischaemic encephalopathy

Elucidating metabolic effects of hypoxic-ischaemic encephalopathy (HIE) may reveal early biomarkers of injury and new treatment targets. This study uses untargeted metabolomics to examine early metabolic alterations in a carefully defined neonatal population. Infants with perinatal asphyxia who were resuscitated at birth and recovered (PA group), those who developed HIE (HIE group) and healthy controls were all recruited at birth. Metabolomic analysis of cord blood was performed using direct infusion FT-ICR mass spectrometry. For each reproducibly detected metabolic feature, mean fold differences were calculated HIE vs. controls (ΔHIE) and PA vs. controls (ΔPA). Putative metabolite annotations were assigned and pathway analysis was performed. Twenty-nine putatively annotated metabolic features were significantly different in ΔPA after false discovery correction ( q < 0.05), with eight of these also significantly altered in ΔHIE. Altered putative metabolites included; melatonin, leucine, kynurenine and 3-hydroxydodecanoic acid which differentiated between infant groups (ΔPA and ΔHIE); and D-erythrose-phosphate, acetone, 3-oxotetradecanoic acid and methylglutarylcarnitine which differentiated across severity grades of HIE. Pathway analysis revealed ΔHIE was associated with a 50% and 75% perturbation of tryptophan and pyrimidine metabolism, respectively. We have identified perturbed metabolic pathways and potential biomarkers specific to PA and HIE, which measured at birth, may help direct treatment.

Diagnosis of seizures and encephalopathy using conventional EEG and amplitude integrated EEG

Seizures are more common in the neonatal period than at any other time of life, partly due to the relative hyperexcitability of the neonatal brain. Brain monitoring of sick neonates in the NICU using either conventional electroencephalography or amplitude integrated EEG is essential to accurately detect seizures. Treatment of seizures is important, as evidence increasingly indicates that seizures damage the brain in addition to that caused by the underlying etiology. Prompt treatment has been shown to reduce seizure burden with the potential to ameliorate seizure-mediated damage. Neonatal encephalopathy most commonly caused by a hypoxia-ischemia results in an alteration of mental status and problems such as seizures, hypotonia, apnea, and feeding difficulties. Confirmation of encephalopathy with EEG monitoring can act as an important adjunct to other investigations and the clinical examination, particularly when considering treatment strategies such as therapeutic hypothermia. Brain monitoring also provides useful early prognostic indicators to clinicians. Recent use of machine learning in algorithms to continuously monitor the neonatal EEG, detect seizures, and grade encephalopathy offers the exciting prospect of real-time decision support in the NICU in the very near future.

RNA-sequencing analysis of umbilical cord plasma microRNAs from healthy newborns

MicroRNAs are a class of small non-coding RNA that regulate gene expression at a post-transcriptional level. MicroRNAs have been identified in various body fluids under normal conditions and their stability as well as their dysregulation in disease has led to ongoing interest in their diagnostic and prognostic potential. Circulating microRNAs may be valuable predictors of early-life complications such as birth asphyxia or neonatal seizures but there are relatively few data on microRNA content in plasma from healthy babies. Here we performed small RNA-sequencing analysis of plasma processed from umbilical cord blood in a set of healthy newborns. MicroRNA levels in umbilical cord plasma of four male and four female healthy babies, from two different centres were profiled. A total of 1,004 individual microRNAs were identified, which ranged from 426 to 659 per sample, of which 269 microRNAs were common to all eight samples. Many of these microRNAs are highly expressed and consistent with previous studies using other high throughput platforms. While overall microRNA expression did not differ between male and female cord blood plasma, we did detect differentially edited microRNAs in female plasma compared to male. Of note, and consistent with other studies of this type, adenylation and uridylation were the two most prominent forms of editing. Six microRNAs, miR-128-3p, miR-29a-3p, miR-9-5p, miR-218-5p, 204-5p and miR-132-3p were consistently both uridylated and adenylated in female cord blood plasma. These results provide a benchmark for microRNA profiling and biomarker discovery using umbilical cord plasma and can be used as comparative data for future biomarker profiles from complicated births or those with early-life developmental disorders.

An Approximate Nearest Neighbour System For Neonatal EEG Recall

Clinical neurophysiologists often find it difficult to recall rare EEG patterns despite the fact that this information could be diagnostic and help with treatment intervention. Traditional search methods may take time to retrieve the archived EEGs that could provide the meaning or cause of the specific pattern which is not acceptable as time can be critical for sick neonates. If neurophysiologists had the ability to quickly recall similar patterns, the prior occurrence of the pattern may help make an earlier diagnosis. This paper presents a system that may be used to assist a clinical neurophysiologist in the recall of neonatal EEG patterns. The proposed system consists of an alignment technique followed by an approximate nearest neighbour search algorithm called locality sensitive hashing. The system was tested on six different neonatal EEG pattern types with 430 events in total and the results are presented in this paper.

Validation of Raised Cord Blood Interleukin-16 in Perinatal Asphyxia and Neonatal Hypoxic-Ischaemic Encephalopathy in the BiHiVE2 Cohort

The role of inflammation is an important factor in the progression of hypoxic-ischaemic encephalopathy (HIE). We have previously shown that interleukin-16 (IL-16) is increased in infants with moderate and severe HIE and relates to poor neurodevelopmental outcomes. We aimed to validate IL-16 as a cord blood-based biomarker for HIE and to examine its relationship to long-term outcomes. The study sample consisted of 105 full-term infants who experienced perinatal asphyxia (PA) (with and without an encephalopathy) along with healthy, gestational age-matched newborn controls. Umbilical cord blood serum was processed and biobanked at delivery. Infants were assigned a modified Sarnat score at 24 h. Analysis of IL-16 cytokine cord blood levels was performed using the sandwich-based enzyme-linked immunosorbent assay (ELISA) technique. Cord blood-based IL-16 was increased in infants with PA and HIE relative to controls (p = 0.025). IL-16 was also increased in the HIE group relative to controls (p = 0.042). There was no significant difference in IL-16 across grades of HIE or in those with abnormal outcomes at 2 years of age. This study validates findings that cord blood-based IL-16 levels are increased in infants with PA, including those who go on to develop HIE.

Altered Expression of Umbilical Cord Blood Levels of miR-181b and Its Downstream Target mUCH-L1 in Infants with Moderate and Severe Neonatal Hypoxic-Ischaemic Encephalopathy

Hypoxic-ischaemic encephalopathy (HIE) remains one of the leading causes of neurological disability worldwide. No blood biomarker capable of early detection and classification of injury severity in HIE has been identified. This study aimed to investigate the potential of miRNA-181b (miR-181b) and its downstream target, ubiquitin C-terminal hydrolase-L1 (UCH-L1), to predict the severity of HIE. Full-term infants with perinatal asphyxia were recruited at birth and observed for the development of HIE, along with healthy controls. Levels of miR-181b and messenger UCH-L1 (mUCH-L1) in umbilical cord blood were determined using qRT-PCR. In total, 131 infants; 40 control, 50 perinatal asphyxia without HIE (PA) and 41 HIE, recruited across two separate cohorts (discovery and validation) were included in this study. Significant and consistent downregulation of miR-181b was observed in infants with moderate/severe HIE compared to all other groups in both cohorts: discovery 0.25 (0.16-0.32) vs 0.61 (0.26-1.39), p = 0.027 and validation 0.33 (0.15-1.78) vs 1.2 (0.071-2.09), p = 0.035. mUCH-L1 showed increased expression in infants with HIE in both cohorts. The expression ratio of miR-181b to mUCH-L1 was reduced in those infants with moderate/severe HIE in both cohorts: discovery cohort 0.23 (0.06-0.44) vs 1.59 (0.46-2.54), p = 0.01 and validation cohort 0.41 (0.10-0.81) vs 1.38 (0.59-2.56) in all other infants, p = 0.009. We have validated consistent patterns of altered expression in miR-181b/mUCH-L1 in moderate/severe neonatal HIE which may have the potential to guide therapeutic intervention in HIE.

Respiratory adaptation in term infants following elective caesarean section

OBJECTIVE

To determine respiratory rate (RR), tidal volume (TV) and end-tidal carbon dioxide (EtCO₂) values in full-term infants immediately after caesarean section, and to assess whether infants that develop transient tachypnoea of the newborn (TTN) follow the same physiological patterns.

DESIGN AND PATIENTS

A Respironics NM3 Monitor (Philips, Netherlands) continuously measured RR, TV and EtCO₂ for 7 min in infants >37 weeks' gestation following elective caesarean section (ECS). Monitoring was repeated at 2 hours of age for 2 min. Gestation, birth weight, Apgar scores and admissions to neonatal unit were documented.

SETTING

The operative delivery theatre of Cork University Maternity Hospital, Ireland.

RESULTS

There were 95 term infants born by ECS included. Median (IQR) gestation was 39 weeks (38.2-39.1) and median (IQR) birth weight 3420 g (3155-3740). Median age at initiation of monitoring was 26.5 s (range: 20-39). Data were analysed for the first 7 min of life. Mean breaths per minute (bpm) increased over the first 7 min of life (44.31-61.62). TV and EtCO₂ values were correlated and increased from 1 min until maximum mean values were recorded at 3 min after delivery (5.18 mL/kg-6.44 mL/kg, and 4.32 kPa-5.64 kPa, respectively). Infants admitted to the neonatal unit with TTN had significantly lower RRs from 2 min of age compared with infants not admitted for TTN.

CONCLUSIONS

TV and EtCO₂ values are correlated and increase significantly over the first few minutes following ECS. RR increases gradually from birth, and rates were lower in infants that develop TTN.

Complex spectrum of phenobarbital effects in a mouse model of neonatal hypoxia-induced seizures

Seizures in neonates, mainly caused by hypoxic-ischemic encephalopathy, are thought to be harmful to the brain. Phenobarbital remains the first line drug therapy for the treatment of suspected neonatal seizures but concerns remain with efficacy and safety. Here we explored the short- and long-term outcomes of phenobarbital treatment in a mouse model of hypoxia-induced neonatal seizures. Seizures were induced in P7 mice by exposure to 5% O₂ for 15 minutes. Immediately after hypoxia, pups received a single dose of phenobarbital (25 mg.kg^-1) or saline. We observed that after administration of phenobarbital seizure burden and number of seizures were reduced compared to the hypoxic period; however, PhB did not suppress acute histopathology. Behavioural analysis of mice at 5 weeks of age previously subjected to hypoxia-seizures revealed an increase in anxiety-like behaviour and impaired memory function compared to control littermates, and these effects were not normalized by phenobarbital. In a seizure susceptibility test, pups previously exposed to hypoxia, with or without phenobarbital, developed longer and more severe seizures in response to kainic acid injection compared to control mice. Unexpectedly, mice treated with phenobarbital developed less hippocampal damage after kainic acid than untreated counterparts. The present study suggests phenobarbital treatment in immature mice does not improve the long lasting functional deficits induces by hypoxia-induced seizures but, unexpectedly, may reduce neuronal death caused by exposure to a second seizure event in later life.

Mild hypoxic ischaemic encephalopathy and long term neurodevelopmental outcome - A systematic review

AIMS

Hypoxic ischaemic encephalopathy (HIE) remains a significant cause of long term neurodisability despite therapeutic hypothermia (TH). Infants with mild HIE, representing 50% of those with HIE, are perceived as low risk and are currently not eligible for TH [1]. This review examines the available evidence of outcome in term infants with mild HIE.

METHODS

Medline, Embase and Cochrane Clinical Trials databases were searched in March 2017. Studies with well-defined HIE grading at birth and standardised neurodevelopmental assessment at ≥18 months were included. Abnormal outcome was defined as death, cerebral palsy or standardised neurodevelopmental test score more than 1 standard deviation below the mean.

RESULT

Twenty studies were included. Abnormal outcome was reported in 86/341 (25%) of infants. There was insufficient evidence to examine the effect of TH on outcome.

CONCLUSION

A significant proportion of infants with mild HIE have abnormal outcome at follow up.

Mild prenatal hypoxia-ischemia leads to social deficits and central and peripheral inflammation in exposed offspring

Hypoxic-ischemic encephalopathy (HIE) resulting from intrauterine or perinatal hypoxic-ischemia (HI) is a leading cause of long-term neonatal neurodisability. While most studies of long-term outcome have focused on moderate and severe HIE in term infants, recent work has shown that those with mild HIE may have subtle neurological impairments. However, the impact of mild HI on pre-term infants is much less clear given that pre-term birth is itself a risk factor for neurodisability. Here we show that mild HI insult alters behaviour, inflammation and the corticosterone stress response in a rat model of pre-term HIE. Mild HI exposure led to social deficits in exposed offspring at postnatal day 30, without impairments in the novel object recognition test nor in the open field test. This was also accompanied by elevations in circulating adrenocorticotropic hormone and corticosterone indicating an exaggerated stress response. There were also elevations in il-1β and il-6 but not tnf-α mRNA and protein in the brain and blood samples. In summary we find that a mild HI exposure leads to social deficits, central and peripheral inflammation, and an abnormal corticosterone response which are three core features of autism spectrum disorder. This shows that mild HI exposure may be a risk factor for an abnormal neurodevelopmental outcome in pre-term offspring.

Toward a Personalized Real-Time Diagnosis in Neonatal Seizure Detection

The problem of creating a personalized seizure detection algorithm for newborns is tackled in this paper. A probabilistic framework for semi-supervised adaptation of a generic patient-independent neonatal seizure detector is proposed. A system that is based on a combination of patient-adaptive (generative) and patient-independent (discriminative) classifiers is designed and evaluated on a large database of unedited continuous multichannel neonatal EEG recordings of over 800 h in duration. It is shown that an improvement in the detection of neonatal seizures over the course of long EEG recordings is achievable with on-the-fly incorporation of patient-specific EEG characteristics. In the clinical setting, the employment of the developed system will maintain a seizure detection rate at 70% while halving the number of false detections per hour, from 0.4 to 0.2 FD/h. This is the first study to propose the use of online adaptation without clinical labels, to build a personalized diagnostic system for the detection of neonatal seizures.

A review of important electroencephalogram features for the assessment of brain maturation in premature infants

This review describes the maturational features of the baseline electroencephalogram (EEG) in the neurologically healthy preterm infant. Features such as continuity, sleep state, synchrony and transient waveforms are described, even from extremely preterm infants and includes abundant illustrated examples. The physiological significance of these EEG features and their relationship to neurodevelopment are highlighted where known. This review also demonstrates the importance of multichannel conventional EEG monitoring for preterm infants as many of the features described are not apparent if limited channel EEG monitors are used.

CONCLUSION

This review aims to provide healthcare professionals in the neonatal intensive care unit with guidance on the more common normal maturational features seen in the EEG of preterm infants.

Electrographic Seizures during the Early Postnatal Period in Preterm Infants

OBJECTIVE

To investigate the frequency and characteristics of electrographic seizures in preterm infants in the early postnatal period.

STUDY DESIGN

Infants <32 weeks gestational age (GA) (n = 120) were enrolled for continuous multichannel electroencephalography (EEG) recording initiated as soon as possible after birth and continued for approximately up to 72 hours of age. Electrographic seizures were identified visually, annotated, and analyzed. Quantitative descriptors of the temporal evolution of seizures, including total seizure burden, seizure duration, and maximum seizure burden, were calculated.

RESULTS

Median GA was 28.9 weeks (IQR, 26.6-30.3 weeks) and median birth weight was 1125 g (IQR, 848-1440 g). Six infants (5%; 95% CI, 1.9-10.6%) had electrographic seizures. Median total seizure burden, seizure duration, and maximum seizure burden were 40.3 minutes (IQR, 5.0-117.5 minutes), 49.6 seconds (IQR, 43.4-76.6 seconds), and 10.8 minutes/hour (IQR, 1.6-20.2 minutes/hour), respectively. Seizure burden was highest in 2 infants with significant abnormalities on neuroimaging.

CONCLUSION

Electrographic seizures are infrequent within the first few days of birth in very preterm infants. Seizures in this population are difficult to detect accurately without continuous multichannel EEG monitoring.

The ability of early serial developmental assessment to predict outcome at 5years following neonatal hypoxic-ischaemic encephalopathy

BACKGROUND

Neurodevelopmental difficulties in children following hypoxic-ischaemic encephalopathy (HIE) may not emerge until school age.

AIMS

To evaluate the value and stability of early serial developmental assessments in predicting long-term outcome.

STUDY DESIGN

Prospective study of infants with neonatal HIE and early continuous EEG at birth.

SUBJECTS

Term infants with HIE were recruited at birth. Development was measured at 6, 12 and 24months using the Revised Griffiths' Scales (GMDS-R).

OUTCOME MEASURES

Intellectual abilities at age five were measured using the Wechsler Preschool & Primary Scale of Intelligence (WPPSI-III^UK) and the 'numbers' subtest from the Children's Memory Scale. Overall five-year outcome was also reported.

RESULTS

IQ outcome was available in forty-seven surviving children (28 male, 19 female: mean (SD) age 64.0(5.7) months. Mean processing speed (p=0.01) and short-term verbal memory (p=0.005) were below the norm. Global development (GDQ) at 6, 12 and 24months correlated (p<0.01) with five-year global, verbal and performance IQ with improved correlation over time. Normal GDQ throughout early childhood predicted normal IQ at 5years (24month AUROC value=0.941, p=0.001). An abnormal early GDQ score at any stage in the first 24months had excellent negative predictive values, superior to those for neonatal Sarnat and EEG grading.

CONCLUSIONS

Normal early development predicts normal 5year IQ with prediction increasing over time. Repeated measurement is warranted due to instability of findings across the first two years. Follow-up for children with abnormal early development is warranted given high sensitivity for school-age global abnormal outcome.

Features of cerebral oxygenation detects brain injury in premature infants

Babies born prematurely can develop brain injury within days after birth. Early identification of high-risk infants enables appropriate clinical care to mitigate potential lifelong disabilities. Near infra-red spectroscopy is an established technology that can provide continuous measurements of cerebral oxygen saturation (rcSO₂) over this critical period. We develop a feature set of the rcSO₂ signal for the purpose of detecting brain injury. Our feature set contains amplitude, spectral, and fractal dimension features within 5 frequency bands. Features are combined in a support vector machine (SVM) and performance is assessed within a cross-validation procedure. Using a cohort of 47 infants of <;32 weeks of gestation, we find significant (p <; 0.05) features of amplitude in the frequency band 0.9-3.6 mHz and a fractal dimension measure in the frequency band 1.8-3.6 mHz. The SVM has an area-under the receiver operator characteristic (AUC) of 0.75 with sensitivity-specificity values of 67-77%. These moderate results highlight the potential for quantitative analysis of rcSO₂ to detect brain injury and thus enable early identification of high-risk infants.

Cord Blood IL-16 Is Associated with 3-Year Neurodevelopmental Outcomes in Perinatal Asphyxia and Hypoxic-Ischaemic Encephalopathy

Activation of the inflammatory pathway is increasingly recognized as an important mechanism of injury following neonatal asphyxia and encephalopathy. This process may contribute to the poor prognosis seen in some cases, despite therapeutic hypothermia. Our group has previously identified raised interleukin (IL)-6 and IL-16, measured in umbilical cord blood at birth, to be predictive of grade of hypoxic-ischaemic encephalopathy (HIE). Our aim in this study was to examine the ability of these cytokines to predict the 3-year neurodevelopmental outcome in the same cohort. As part of a prospective, longitudinal cohort study set in a single tertiary maternity unit, term infants with biochemical and clinical evidence of perinatal asphyxia were recruited at birth. Umbilical cord blood was collected and analyzed for IL-6 and IL-16 using a Luminex assay. The neurodevelopmental outcome of these infants was assessed at 3 years using the Bayley Scales of Infant and Toddler Development (Edition 3). Early cord blood measurement of IL-6 and IL-16 and long-term outcome were available in 33/69 infants. Median (IQR) IL-16 differentiated infants with a severely abnormal outcome (n = 6) compared to all others (n = 27), (646 [466-1,085] vs. 383.5 [284-494] pg/mL; p = 0.012). IL-16 levels were able to predict a severe outcome with an area under the receiver-operating characteristic (ROC) curve of 0.827 (95% CI 0.628-1.000; p = 0.014). Levels ≥514 pg/mL predicted a severe outcome with a sensitivity of 83% and a specificity of 81%. IL-16 also outperformed other routine biochemical markers available at birth for the prediction of severe outcome. APGAR scores at 1 and 10 min were also predictive of a severe outcome (p = 0.022 and p = 0.036, respectively). A combination of IL-16 with these clinical markers did not improve predictive value, but IL-16 combined with electroencephalogram grading increased the area under the ROC curve. IL-6 did not show any association with 3-year outcome. This is the first report studying the association of IL-16 measured at birth with long-term outcome in a cohort of neonates with perinatal asphyxia. IL-16 may be an early biomarker of severe injury and aid in the long-term prognostication in infants with HIE.

Detecting bursts in the EEG of very and extremely premature infants using a multi-feature approach

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Machine learning approach enables accurate detection of bursts in preterm EEG.

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Features of amplitude and spectral shape capture discriminating information.

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Improves reliability of estimates of inter-burst intervals.

Aim: To develop a method that segments preterm EEG into bursts and inter-bursts by extracting and combining multiple EEG features. Methods: Two EEG experts annotated bursts in individual EEG channels for 36 preterm infants with gestational age < 30 weeks. The feature set included spectral, amplitude, and frequency-weighted energy features. Using a consensus annotation, feature selection removed redundant features and a support vector machine combined features. Area under the receiver operator characteristic (AUC) and Cohen’s kappa (κ) evaluated performance within a cross-validation procedure. Results: The proposed channel-independent method improves AUC by 4–5% over existing methods (p < 0.001, n=36), with median (95% confidence interval) AUC of 0.989 (0.973–0.997) and sensitivity–specificity of 95.8–94.4%. Agreement rates between the detector and experts’ annotations, κ=0.72 (0.36–0.83) and κ=0.65 (0.32–0.81), are comparable to inter-rater agreement, κ=0.60 (0.21–0.74). Conclusions: Automating the visual identification of bursts in preterm EEG is achievable with a high level of accuracy. Multiple features, combined using a data-driven approach, improves on existing single-feature methods.

EEG - A Valuable Biomarker of Brain Injury in Preterm Infants

This review focuses on the role of electroencephalography (EEG) in monitoring abnormalities of preterm brain function. EEG features of the most common developmental brain injuries in preterm infants, including intraventricular haemorrhage, periventricular leukomalacia, and perinatal asphyxia, are described. We outline the most common EEG biomarkers associated with these injuries, namely seizures, positive rolandic sharp waves, EEG suppression/increased interburst intervals, mechanical delta brush activity, and other deformed EEG waveforms, asymmetries, and asynchronies. The increasing survival rate of preterm infants, in particular those that are very and extremely preterm, has led to a growing demand for a specific and shared characterization of the patterns related to adverse outcome in this unique population. This review includes abundant high-quality images of the EEG patterns seen in premature infants and will provide a valuable resource for everyone working in developmental neuroscience.

Heart rate variability in hypoxic ischemic encephalopathy during therapeutic hypothermia

BACKGROUND

Therapeutic hypothermia (TH) aims to ameliorate further injury in infants with moderate and severe hypoxic ischemic encephalopathy (HIE). We aim to assess the effect of TH on heart rate variability (HRV) in infants with HIE.

METHODS

Multichannel video-electroencephalography (EEG) and electrocardiography were assessed at 6-72 h after birth in full-term infants with HIE, recruited prior to (pre-TH group) and following (TH group) the introduction of TH in our neonatal unit. HIE severity was graded using EEG. HRV features investigated include: mean NN interval (mean NN), standard deviation of NN interval (SDNN), triangular interpolation (TINN), high-frequency (HF), low-frequency (LF), very low-frequency (VLF), and LF/HF ratio. Linear mixed model comparisons were used.

RESULTS

118 infants (pre-TH: n = 44, TH: n = 74) were assessed. The majority of HRV features decreased with increasing EEG grade. Infants with moderate HIE undergoing TH had significantly different HRV features compared with the pre-TH group (HF: P = 0.016, LF/HF ratio: P = 0.006). In the pre-TH group, LF/HF ratio was significantly different between moderate and severe HIE grades (P = 0.002). In the TH group, significant differences were observed between moderate and severe HIE grades for SDNN: P = 0.020, TINN: P = 0.005, VLF: P = 0.029, LF: P = 0.010, and HF: P = 0.006.

CONCLUSION

The HF component of HRV is increased in infants with moderate HIE undergoing TH.

A Randomized Controlled Trial of End-Tidal Carbon Dioxide Detection of Preterm Infants in the Delivery Room

OBJECTIVE

To compare the ability of qualitative versus quantitative methods of end-tidal carbon dioxide (EtCO₂) detection to maintain normocarbia during face mask ventilation (FMV) of preterm infants (<32 weeks) in the delivery room.

STUDY DESIGN

Preterm infants <32 weeks were randomly assigned to the use of a disposable PediCap EtCO₂ detector (Covidien, Dublin, Ireland) (qualitative) or a Microstream side stream capnography device (Covidien) (quantitative) for FMV in the delivery room, via a NeoPuff T-piece resuscitator (Fisher and Paykel, Auckland, New Zealand). The primary outcome was the presence of normocarbia, based on partial pressure of CO₂ (PaCO₂) readings obtained in the neonatal intensive care unit within an hour of birth. Normocarbia was defined as a PaCO₂ measure between 37.5 and 60 mm Hg (5-8 kPa).

RESULTS

Of the 59 infants included, 59% (35/59) were within the PaCO₂ target range within an hour of birth. There was no difference in the primary outcome; 64% (21/33) of infants in the quantitative group were within the PaCO₂ range compared with 54% (14/26) in the qualitative group (P = .594); and 93% of participants <28 weeks' gestation were within the PaCO₂ normocarbic range (90% [9/10] in quantitative group and 100% [5/5] in the qualitative group [P = 1]). There was no difference in the intubation rate, days of ventilation, or bronchopulmonary dysplasia rates between the 2 groups.

CONCLUSIONS

Quantitative or qualitative EtCO₂ detection methods are both feasible for FMV in the delivery room. Although there was no difference in the incidence of normocarbia, the use of either form of EtCO₂ monitoring should be considered during newborn stabilization, especially in infants less than 28 weeks' gestation.

TRIAL REGISTRATION

ISRCTN: ISRCTN10934870.

Automatic quantification of ischemic injury on diffusion-weighted MRI of neonatal hypoxic ischemic encephalopathy

A fully automatic method for detection and quantification of ischemic lesions in diffusion-weighted MR images of neonatal hypoxic ischemic encephalopathy (HIE) is presented. Ischemic lesions are manually segmented by two independent observers in 1.5 T data from 20 subjects and an automatic algorithm using a random forest classifier is developed and trained on the annotations of observer 1. The algorithm obtains a median sensitivity and specificity of 0.72 and 0.99 respectively. F1-scores are calculated per subject for algorithm performance (median = 0.52) and observer 2 performance (median = 0.56). A paired t-test on the F1-scores shows no statistical difference between the algorithm and observer 2 performances. The method is applied to a larger dataset including 54 additional subjects scanned at both 1.5 T and 3.0 T. The algorithm findings are shown to correspond well with the injury pattern noted by clinicians in both 1.5 T and 3.0 T data and to have a strong relationship with outcome. The results of the automatic method are condensed to a single score for each subject which has significant correlation with an MR score assigned by experienced clinicians (p < 0.0001). This work represents a quantitative method of evaluating diffusion-weighted MR images in neonatal HIE and a first step in the development of an automatic system for more in-depth analysis and prognostication.

Effects of P2X7 receptor antagonists on hypoxia-induced neonatal seizures in mice

Neonatal seizures are a common consequence of hypoxic/ischemic encephalopathy (HIE). Phenobarbital remains the frontline treatment for neonatal seizures but is often ineffective. The P2X7 receptor (P2X7R) is a cell surface-expressed ionotropic receptor activated by high amounts of ATP which may be released during seizures or as a consequence of tissue injury. Here, we explored the role of the P2X7R in a mouse model of neonatal seizures induced by hypoxia. Exposure of postnatal day 7 (P7) mouse pups to global hypoxia (5% O₂ for 15 min) produced electrographically-defined seizures with behavioural correlates that persisted after restitution of normoxia. Expression of the P2X7R showed age-dependent increases in the hippocampus and neocortex of developing mice and was present in human neonatal brain. P2X7R transcript and protein levels were increased 24 h after neonatal hypoxia-induced seizures in mouse pups. EEG recordings in pups determined that injection of the P2X7R antagonist A-438079 (25 mg/kg^-1, intraperitoneal) reduced electrographic seizure number, EEG power and spiking during hypoxia. A-438079 did not reduce post-hypoxia seizures. Caspase-1 processing and molecular markers of inflammation and microglia were reduced in A438079-treated mice. Electrographic seizure-suppressive effects were also observed with a second P2X7R antagonist, JNJ-47965567, in the same model. The present study shows hypoxia-induced seizures alter expression of purinergic and neuroinflammatory signalling components and suggest potential applications but also limitations of the P2X7R as a target for the treatment of HIE and other causes of neonatal seizures.

Lost in Transition: A Systematic Review of Neonatal Electroencephalography in the Delivery Room-Are We Forgetting an Important Biomarker for Newborn Brain Health?

BACKGROUND

Electroencephalography (EEG) monitoring is routine in neonatal intensive care units (NICUs) for detection of seizures, neurological monitoring of infants following perinatal asphyxia, and increasingly, following preterm delivery. EEG monitoring is not routinely commenced in the delivery room (DR).

OBJECTIVES

To determine the feasibility of recording neonatal EEG in the DR, and to assess its usefulness as a marker of neurological well-being during immediate newborn transition.

METHODS

We performed a systematic stepwise search of PubMed using the following terms: infant, newborns, neonate, DR, afterbirth, transition, and EEG. Only human studies describing EEG monitoring in the first 15 min following delivery were included. Infants of all gestational ages were included.

RESULTS

Two original studies were identified that described EEG monitoring of newborn infants within the DR. Both prospective observational studies used amplitude-integrated EEG (aEEG) monitoring and found it feasible in infants >34 weeks' gestation; however, technical challenges made it difficult to obtain continuous reliable data. Different EEG patterns were identified in uncompromised newborns and those requiring resuscitation.

CONCLUSION

EEG monitoring is possible in the DR and may provide an objective baseline measure of neurological function. Further feasibility studies are required to overcome technical challenges in the DR, but these challenges are not insurmountable with modern technology.

Downstream mRNA Target Analysis in Neonatal Hypoxic-Ischaemic Encephalopathy Identifies Novel Marker of Severe Injury: a Proof of Concept Paper

Human microRNA miR-374a is downregulated in the umbilical cord blood (UCB) of infants with hypoxic-ischaemic encephalopathy (HIE). The downstream targets of this microRNA (miRNA) are unclear, but one putative target is the activin-A receptor type IIb (ACVR2B). ACVR2B is required for activin-A function and previous reports have shown alterations of activin-A levels in neonatal HIE. Our aim was to investigate the expression of the potential downstream targets of miR-374a, activin-A and ACVR2B, at birth in a cohort of full-term infants with perinatal asphyxia (PA) only, and those with PA who developed clinical and electrographic HIE. UCB was drawn and processed immediately after delivery. Levels of serum activin-A were measured using ELISA. mRNA levels of ACVR2B in whole blood were quantified using qRT-PCR. Outcome was assessed at 3 years of age using standardised developmental assessment. In total, 171 infants were enrolled: 88 healthy controls, 56 PA and 27 HIE. A statistically significant elevation of median (IQR) ACVR2B was detected in infants with severe HIE compared to moderate/mild HIE, PA and control groups (3.3 (2.94-3.67) vs. 0.91 (0.55-1.21) vs. 0.88 (0.57-1.38) vs. 0.84 (0.74-1.24), p values = 0.04, 0.027 and 0.025, respectively). Although serum activin-A levels were elevated in infants with severe HIE, this elevation did not reach significance. ACVR2B may be a potential novel marker of HIE severity. This is the first study to examine the relationship between activin-A, its receptor AVCR2B and potentially upstream miRNA miR-374a in a cohort of carefully categorised and phenotyped infants. We have shown that miRNA analysis, combined with downstream target exploration, may yield novel biomarkers for the prediction of HIE severity.

Seizure burden and neurodevelopmental outcome in neonates with hypoxic-ischemic encephalopathy

AIM

To examine the relationship between electrographic seizures and long-term outcome in neonates with hypoxic-ischemic encephalopathy (HIE).

METHOD

Full-term neonates with HIE born in Cork University Maternity Hospital from 2003 to 2006 (pre-hypothermia era) and 2009 to 2012 (hypothermia era) were included in this observational study. All had early continuous electroencephalography monitoring. All electrographic seizures were annotated. The total seizure burden and hourly seizure burden were calculated. Outcome (normal/abnormal) was assessed at 24 to 48 months in surviving neonates using either the Bayley Scales of Infant and Toddler Development, Third Edition or the Griffiths Mental Development Scales; a diagnosis of cerebral palsy or epilepsy was also considered an abnormal outcome.

RESULTS

Continuous electroencephalography was recorded for a median of 57.1 hours (interquartile range 33.5-80.5h) in 47 neonates (31 males, 16 females); 29 out of 47 (62%) had electrographic seizures and 25 out of 47 (53%) had an abnormal outcome. The presence of seizures per se was not associated with abnormal outcome (p=0.126); however, the odds of an abnormal outcome increased over ninefold (odds ratio [OR] 9.56; 95% confidence interval [95% CI] 2.43-37.67) if a neonate had a total seizure burden of more than 40 minutes (p=0.001), and eightfold (OR: 8.00; 95% CI: 2.06-31.07) if a neonate had a maximum hourly seizure burden of more than 13 minutes per hour (p=0.003). Controlling for electrographic HIE grade or treatment with hypothermia did not change the direction of the relationship between seizure burden and outcome.

INTERPRETATION

In HIE, a high electrographic seizure burden is significantly associated with abnormal outcome, independent of HIE severity or treatment with hypothermia.

Decreased Variability and Low Values of Perfusion Index on Day One Are Associated with Adverse Outcome in Extremely Preterm Infants

OBJECTIVE

To develop new quantitative features for the Perfusion Index signal recorded continuously over the first 24 hours of life in a cohort of extremely low gestational age newborns and to assess the association of these features with normal and adverse short-term outcome.

STUDY DESIGN

A cohort study of extremely low gestational age newborns. Adverse outcome was defined as early mortality before 72 hours of life, acquired severe periventricular-intraventricular hemorrhage, or severe cystic leukomalacia. Perfusion Index values were obtained from the plethysmographic signal of a pulse oximeter. Perfusion Index signals were separated into low-frequency (trend) and high-frequency (detrend) components. Three features were extracted during four 6-hour epochs: mean of the trend component (mean-trend), SD of the trend component (SD-trend), and SD of the detrend component (SD-detrend). The SD features represent long-term variability (SD-trend) and short-term variability (SD-detrend) of the Perfusion Index. A mixed-effects model was fitted to each feature.

RESULTS

Ninety-nine infants were included in the analysis. Quadratic-time mixed-effects models provided the best fit for all 3 features. The mean-trend component was lower for the adverse outcome compared with the normal outcome group with a difference of 0.142 Perfusion Index (P = .001). SD-detrend component was also lower for the adverse compared with the normal outcome group, although this difference of 0.031 Perfusion Index/days² was dependent on time (P < .001).

CONCLUSION

Low values and reduced short-term variability of Perfusion Index on day 1 are associated with adverse outcome.

Role of EEG background activity, seizure burden and MRI in predicting neurodevelopmental outcome in full-term infants with hypoxic-ischaemic encephalopathy in the era of therapeutic hypothermia

OBJECTIVE

To investigate the role of EEG background activity, electrographic seizure burden, and MRI in predicting neurodevelopmental outcome in infants with hypoxic-ischaemic encephalopathy (HIE) in the era of therapeutic hypothermia.

METHODS

Twenty-six full-term infants with HIE (September 2011-September 2012), who had video-EEG monitoring during the first 72 h, an MRI performed within the first two weeks and neurodevelopmental assessment at two years were evaluated. EEG background activity at age 24, 36 and 48 h, seizure burden, and severity of brain injury on MRI, were compared and related to neurodevelopmental outcome.

RESULTS

EEG background activity was significantly associated with neurodevelopmental outcome at 36 h (p = 0.009) and 48 h after birth (p = 0.029) and with severity of brain injury on MRI at 36 h (p = 0.002) and 48 h (p = 0.018). All infants with a high seizure burden and moderate-severe injury on MRI had an abnormal outcome. The positive predictive value (PPV) of EEG for abnormal outcome was 100% at 36 h and 48 h and the negative predictive value (NPV) was 75% at 36 h and 69% at 48 h. The PPV of MRI was 100% and the NPV 85%. The PPV of seizure burden was 78% and the NPV 71%.

CONCLUSION

Severely abnormal EEG background activity at 36 h and 48 h after birth was associated with severe injury on MRI and abnormal neurodevelopmental outcome. High seizure burden was only associated with abnormal outcome in combination with moderate-severe injury on MRI.

Artefact detection in neonatal EEG

Artefact detection is an important component of any automated EEG analysis. It is of particular importance in analyses such as sleep state detection and EEG grading where there is no null state. We propose a general artefact detection system (GADS) based on the analysis of the neonatal EEG. This system aims to detect both major and minor artefacts (a distinction based primarily on amplitude). As a result, a two-stage system was constructed based on 14 features extracted from EEG epochs at multiple time scales: [2, 4, 16, 32]s. These features were combined in a support vector machine (SVM) in order to determine the presence of absence of artefact. The performance of the GADS was estimated using a leave-one-out cross-validation applied to a database of hour long recordings from 51 neonates. The median AUC was 1.00 (IQR: 0.95-1.00) for the detection of major artefacts and 0.89 (IQR: 0.83-0.95) for the detection of minor artefacts.

Early EEG Grade and Outcome at 5 Years After Mild Neonatal Hypoxic Ischemic Encephalopathy

OBJECTIVE

More than half of all infants with neonatal hypoxic ischemic encephalopathy (HIE) are graded as mild and do not meet current criteria for therapeutic hypothermia. These infants are often not enrolled in follow-up, and hence our knowledge of their long-term outcome is sparse. We wished to compare 5-year outcomes in a group of infants with mild, moderate, and severe HIE, graded with both early EEG and clinical assessment, none of whom were treated with therapeutic hypothermia.

METHODS

Term infants with HIE and a healthy comparison group were recruited at birth. Both groups had early continuous EEG recordings. Cognitive and motor outcome was assessed at 5 years.

RESULTS

Outcome was available in 53 infants with HIE and 30 infants in the comparison group at 5 years. Infants with mild HIE at birth (n = 22) had significantly lower full-scale IQ, verbal IQ, and performance IQ than comparison infants (n = 30) at 5 years (P = .001, .001, and 0.004, respectively). No difference in cognitive measures was seen between infants with mild and moderate grades HIE. Intact survival at 5 years varied across EEG grade HIE at 6 hours after birth; 75% in mild, 46% in moderate, 43% in major abnormalities, and 0% with inactive EEGs, compared with 97% in the comparison group.

CONCLUSIONS

Survivors of mild HIE, graded clinically or by early EEG, have higher rates of disability than their peers and have cognitive outcomes similar to that of children with moderate encephalopathy in an uncooled HIE cohort.

Application of audio fingerprinting to neonatal EEG

A clinical neurophysiologist must recognize patterns in EEG signals to evaluate the health of a patient's brain activity. Rare or unusual patterns may take time to correctly identify. The ability to automatically assist this recall would be beneficial in ensuring that appropriate measures could be taken in a timely fashion. Audio fingerprinting is a method used to identify songs using only a snippet of the song. Fingerprints are extracted from a sub-section of the song and matched against a database of previously computed fingerprints. In this paper, a fingerprint quantization technique is implemented on neonatal EEG data to attempt to identify sections of EEG data when only seeing a sub-section of the data. The impact of signal distortions is investigated and results from a database of one hour recordings from 40 newborns are presented.

Phenobarbital reduces EEG amplitude and propagation of neonatal seizures but does not alter performance of automated seizure detection

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Phenobarbital reduces both amplitude and propagation of neonatal seizures.

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These changes may help to explain electroclinical uncoupling.

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The performance of our seizure detection algorithm was unaffected.

Objective

Phenobarbital increases electroclinical uncoupling and our preliminary observations suggest it may also affect electrographic seizure morphology. This may alter the performance of a novel seizure detection algorithm (SDA) developed by our group.

The objectives of this study were to compare the morphology of seizures before and after phenobarbital administration in neonates and to determine the effect of any changes on automated seizure detection rates.

Methods

The EEGs of 18 term neonates with seizures both pre- and post-phenobarbital (524 seizures) administration were studied. Ten features of seizures were manually quantified and summary measures for each neonate were statistically compared between pre- and post-phenobarbital seizures. SDA seizure detection rates were also compared.

Results

Post-phenobarbital seizures showed significantly lower amplitude (p < 0.001) and involved fewer EEG channels at the peak of seizure (p < 0.05). No other features or SDA detection rates showed a statistical difference.

Conclusion

These findings show that phenobarbital reduces both the amplitude and propagation of seizures which may help to explain electroclinical uncoupling of seizures. The seizure detection rate of the algorithm was unaffected by these changes.

Significance

The results suggest that users should not need to adjust the SDA sensitivity threshold after phenobarbital administration.

Short-Term Effects of Phenobarbitone on Electrographic Seizures in Neonates

BACKGROUND

Phenobarbitone is the most common first-line anti-seizure drug and is effective in approximately 50% of all neonatal seizures.

OBJECTIVE

To describe the response of electrographic seizures to the administration of intravenous phenobarbitone in neonates using seizure burden analysis techniques.

METHODS

Multi-channel conventional EEG, reviewed by experts, was used to determine the electrographic seizure burden in hourly epochs. The maximum seizure burden evaluated 1 h before each phenobarbitone dose (T-1) was compared to seizure burden in periods of increasing duration after each phenobarbitone dose had been administered (T+1, T+2 to seizure offset). Differences were analysed using linear mixed models and summarized as means and 95% CI.

RESULTS

Nineteen neonates had electrographic seizures and met the inclusion criteria for the study. Thirty-one doses were studied. The maximum seizure burden was significantly reduced 1 h after the administration of phenobarbitone (T+1) [-14.0 min/h (95% CI: -19.6, -8.5); p < 0.001]. The percentage reduction was 74% (IQR: 36-100). This reduction was temporary and not significant within 4 h of administrating phenobarbitone. Subgroup analysis showed that only phenobarbitone doses at 20 mg/kg resulted in a significant reduction in the maximum seizure burden from T-1 to T+1 (p = 0.002).

CONCLUSIONS

Phenobarbitone significantly reduced seizures within 1 h of administration as assessed with continuous multi-channel EEG monitoring in neonates. The reduction was not permanent and seizures were likely to return within 4 h of treatment.

In-depth performance analysis of an EEG based neonatal seizure detection algorithm

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A novel method for in-depth analysis of neonatal seizure detection algorithms is proposed.

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The analysis estimated how seizure features are exploited by automated detectors.

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This method led to significant improvement of the ANSeR algorithm.

Objective

To describe a novel neurophysiology based performance analysis of automated seizure detection algorithms for neonatal EEG to characterize features of detected and non-detected seizures and causes of false detections to identify areas for algorithmic improvement.

Methods

EEGs of 20 term neonates were recorded (10 seizure, 10 non-seizure). Seizures were annotated by an expert and characterized using a novel set of 10 criteria.

ANSeR seizure detection algorithm (SDA) seizure annotations were compared to the expert to derive detected and non-detected seizures at three SDA sensitivity thresholds. Differences in seizure characteristics between groups were compared using univariate and multivariate analysis. False detections were characterized.

Results

The expert detected 421 seizures. The SDA at thresholds 0.4, 0.5, 0.6 detected 60%, 54% and 45% of seizures. At all thresholds, multivariate analyses demonstrated that the odds of detecting seizure increased with 4 criteria: seizure amplitude, duration, rhythmicity and number of EEG channels involved at seizure peak. Major causes of false detections included respiration and sweat artefacts or a highly rhythmic background, often during intermediate sleep.

Conclusion

This rigorous analysis allows estimation of how key seizure features are exploited by SDAs.

Significance

This study resulted in a beta version of ANSeR with significantly improved performance.

Short and long term prognosis in perinatal asphyxia: An update

Interruption of blood flow and gas exchange to the fetus in the perinatal period, known as perinatal asphyxia, can, if significant, trigger a cascade of neuronal injury, leading on to neonatal encephalopathy (NE) and resultant long-term damage. While the majority of infants who are exposed to perinatal hypoxia-ischaemia will recover quickly and go on to have a completely normal survival, a proportion will suffer from an evolving clinical encephalopathy termed hypoxic-ischaemic encephalopathy (HIE) or NE if the diagnosis is unclear. Resultant complications of HIE/NE are wide-ranging and may affect the motor, sensory, cognitive and behavioural outcome of the child. The advent of therapeutic hypothermia as a neuroprotective treatment for those with moderate and severe encephalopathy has improved prognosis. Outcome prediction in these infants has changed, but is more important than ever, as hypothermia is a time sensitive intervention, with a very narrow therapeutic window. To identify those who will benefit from current and emerging neuroprotective therapies we must be able to establish the severity of their injury soon after birth. Currently available indicators such as blood biochemistry, clinical examination and electrophysiology are limited. Emerging biological and physiological markers have the potential to improve our ability to select those infants who will benefit most from intervention. Biomarkers identified from work in proteomics, metabolomics and transcriptomics as well as physiological markers such as heart rate variability, EEG analysis and radiological imaging when combined with neuroprotective measures have the potential to improve outcome in HIE/NE. The aim of this review is to give an overview of the literature in regards to short and long-term outcome following perinatal asphyxia, and to discuss the prediction of this outcome in the early hours after birth when intervention is most crucial; looking at both currently available tools and introducing novel markers.

Stream computing for biomedical signal processing: A QRS complex detection case-study

Recent developments in "Big Data" have brought significant gains in the ability to process large amounts of data on commodity server hardware. Stream computing is a relatively new paradigm in this area, addressing the need to process data in real time with very low latency. While this approach has been developed for dealing with large scale data from the world of business, security and finance, there is a natural overlap with clinical needs for physiological signal processing. In this work we present a case study of streams processing applied to a typical physiological signal processing problem: QRS detection from ECG data.

Enhanced Monitoring of the Preterm Infant during Stabilization in the Delivery Room

Monitoring of preterm infants in the delivery room (DR) remains limited. Current guidelines suggest that pulse oximetry should be available for all preterm infant deliveries, and that if intubated a colorimetric carbon dioxide detector should provide verification of correct endotracheal tube placement. These two methods of assessment represent the extent of objective monitoring of the newborn commonly performed in the DR. Monitoring non-invasive ventilation effectiveness (either by capnography or respiratory function monitoring) and cerebral oxygenation (near-infrared spectroscopy) is becoming more common within research settings. In this article, we will review the different modalities available for cardiorespiratory and neuromonitoring in the DR and assess the current evidence base on their feasibility, strengths, and limitations during preterm stabilization.

Early Cord Metabolite Index and Outcome in Perinatal Asphyxia and Hypoxic-Ischaemic Encephalopathy

BACKGROUND

A 1H-NMR-derived metabolomic index based on early umbilical cord blood alterations of succinate, glycerol, 3-hydroxybutyrate and O-phosphocholine has shown potential for the prediction of hypoxic-ischaemic encephalopathy (HIE) severity.

OBJECTIVE

To evaluate whether this metabolite score can predict 3-year neurodevelopmental outcome in infants with perinatal asphyxia and HIE, compared with current standard biochemical and clinical markers.

METHODS

From September 2009 to June 2011, infants at risk of perinatal asphyxia were recruited from a single maternity hospital. Cord blood was drawn and biobanked at delivery. Neonates were monitored for development of encephalopathy both clinically and electrographically. Neurodevelopmental outcome was assessed at 36-42 months using the Bayley Scales of Infant and Toddler Development, ed. III (BSID-III). Death and cerebral palsy were also considered as abnormal end points.

RESULTS

Thirty-one infants had both metabolomic analysis and neurodevelopmental outcome at 36-42 months. No child had a severely abnormal BSID-III result. The metabolite index significantly correlated with outcome (ρ2 = 0.30, p < 0.01), which is robust to predict both severe outcome (area under the receiver operating characteristic curve: 0.92, p < 0.01) and intact survival (0.80, p = 0.01). There was no correlation between the index score and performance in the individual BSID-III subscales (cognitive, language, motor).

CONCLUSIONS

The metabolite index outperformed other standard biochemical markers at birth for prediction of outcome at 3 years, but was not superior to EEG or the Sarnat score.

Delivery room end tidal CO2 monitoring in preterm infants <32 weeks

OBJECTIVES

To determine the feasibility of end tidal (EtCO2) monitoring of preterm infants in the delivery room, to determine EtCO2 levels during delivery room stabilisation, and to examine the incidence of normocapnia (5-8 kPa) on admission to the neonatal intensive care unit in the EtCO2 monitored group compared with a historical cohort without EtCO2 monitoring.

PATIENTS AND METHODS

Preterm infants (<32 weeks) were eligible for inclusion in this observational study. The evolution of EtCO2 values immediately after delivery was assessed and linear least-squares methods were used to fit a line to EtCO2 recordings. The partial pressure of CO2 in blood (PCO2) from the infants who received EtCO2 monitoring was compared with a historical cohort without EtCO2 monitoring.

RESULTS

EtCO2 monitoring was feasible in the delivery room. EtCO2 values were successfully obtained in 39 (88.7%) of the 44 infants included in the study. EtCO2 gradually increased over the first 4 min. Intubated infants had higher EtCO2 values compared with infants who were not intubated, with median (IQR) values of 4.7 (3.3-8.4) kPa versus 3.2 (2.6-4.2) kPa (p=0.05). No difference was found between the proportions of PCO2 values within the range of normocapnia among infants who received EtCO2 monitoring compared with those who did not (56.8% vs 47.9%, p=0.396).

CONCLUSIONS

Delivery room EtCO2 monitoring is feasible and safe. EtCO2 values obtained after birth reflect the establishment of functional residual capacity and effective ventilation. The potential short-term and long-term consequences of EtCO2 monitoring should be established in randomised controlled trials.