Monitoring of newborns at high risk for brain injury

Current Evidence: Seizures in Extremely Low Gestational Age Newborns (ELGANs)

Extremely low gestational age newborns (ELGANs) are born at or below 28 weeks of gestational age. Despite improved obstetric care, the incidence of preterm birth continues to rise in advanced countries. Preterm birth remains a major cause of infant mortality, and for infants who survive, neonatal seizures are a significant predictor of later neurologic morbidity. However, little is known about risk factors for neonatal seizures in ELGANs. Understanding the association between neonatal seizures and the development of other neurologic disorders is important given the increasing prevalence of ELGANs. Identifying risk factors that contribute to the development of neonatal seizures in ELGANs may offer insights into novel mechanisms of epileptogenesis in the developing brain and improvements in the prevention or treatment of seizures in preterm infants, including ELGANs. In this literature review, we outline the limitations of epidemiologic studies of neonatal seizures in ELGANs and discuss risk factors for neonatal seizures.

A Comparative Study of EEG and aEEG in Seizure Diagnosis in Infants Admitted to the NICU

Objectives

Seizure is a common sign in neonates hospitalized in the neonatal intensive care units (NICU) that may lead to morbidity and mortality. Most neonatal seizures are subclinical. Conventional EEG (cEEG) is the gold standard for detecting and monitoring seizures but is not widely available. Amplitude-integrated electroencephalography (aEEG) has been used for over a decade to evaluate infants with seizures. In this study, we tried to determine the efficacy of aEEG as a widely available diagnostic tool in diagnosing seizures.

Materials & Methods

All cases with seizures or suspicious seizures were admitted to the NICU of the Children's Medical Center for one year. cEEG and aEEG were performed for these infants. aEEG was recorded for at least six hours with a description of the tracing. Clinical information, outcomes, and questionnaires (patient information) were recorded in detail. The obtained data were analyzed with the SPSS version 24 software.

Results

Eleven out of twenty-five aEEG recordings were abnormal; other patients showed normal aEEGs. The most common clinical and neurological manifestations were seizure (68%) and hypotonia (28%); the mortality rate was 12%. No significant correlation was observed between aEEG findings and gender, age, familial relation, outcome, ultrasound result, type of seizure, and underlying disease.

Conclusion

Studies showed variable sensitivity and specificity values for aEEG. aEEG cannot be recommended as the only way to diagnose and manage seizures in neonates. However, Good accessibility and ease of working with aEEG promote a tendency to use this procedure as a screening tool.

Expert consensus on grading management of electroencephalogram monitoring in neonates

Neonatal electroencephalogram (EEG) monitoring guidelines have been published by American Clinical Neurophysiology Society, and the expert consensus on neonatal amplitude-integrated EEG (aEEG) has also been published in China. It is difficult to strictly follow the guidelines or consensus for EEG monitoring in different levels of neonatal units due to a lack of EEG monitoring equipment and professional interpreters. The Subspecialty Group of Neonatology, Society of Pediatrics, Chinese Medical Association, established an expert group composed of professionals in neonatology, pediatric neurology, and brain electrophysiology to review published guidelines and consensuses and the articles in related fields and propose grading management recommendations for EEG monitoring in different levels of neonatal units. Based on the characteristics of video EEG and aEEG, local medical resources, and disease features, the expert group recommends that video EEG and aEEG can complement each other and can be used in different levels of neonatal units. The consensus also gives recommendations for promoting collaboration between professionals in neonatology, pediatric neurology, and brain electrophysiology and implementing remote EEG monitoring.

Cranial Ultrasound Screening Protocols for Very Preterm Infants

Cranial ultrasound examinations are routinely performed in very preterm neonates. There is no widespread agreement on the optimal timing of these examinations. This review examines screening protocols and recommendations available for the timing of cranial ultrasound examinations in preterm neonates born before 32 wk of gestation. A systematic search was performed to find published screening protocols, and 18 articles were included in the final review. The protocols varied in their recommendations on timing, although at least one examination in the first week of life was universally recommended. The recommended timing for a "late" or final ultrasound examination was variable, and included at 6 wks of postnatal age, term-equivalent age or hospital discharge. There was no agreement as to whether weekly or fortnightly sequential ultrasound imaging should be performed after the first week of life. Further studies are required to establish an optimal protocol for these very preterm neonates to improve detection and monitoring of brain injuries.

Preterm Newborn Presence Detection in Incubator and Open Bed Using Deep Transfer Learning

Video-based motion analysis recently appeared to be a promising approach in neonatal intensive care units for monitoring the state of preterm newborns since it is contact-less and noninvasive. However it is important to remove periods when the newborn is absent or an adult is present from the analysis. In this paper, we propose a method for automatic detection of preterm newborn presence in incubator and open bed. We learn a specific model for each bed type as the camera placement differs a lot and the encountered situations are different between both. We break the problem down into two binary classifications based on deep transfer learning that are fused afterwards: newborn presence detection on the one hand and adult presence detection on the other hand. Moreover, we adopt a strategy of decision intervals fusion in order to take advantage of temporal consistency. We test three deep neural network that were pre-trained on ImageNet: VGG16, MobileNetV2 and InceptionV3. Two classifiers are compared: support vector machine and a small neural network. Our experiments are conducted on a database of 120 newborns. The whole method is evaluated on a subset of 25 newborns including 66 days of video recordings. In incubator, we reach a balanced accuracy of 86%. In open bed, the performance is lower because of a much wider variety of situations whereas less data are available.

The application of magnetic resonance imaging and diffusion-weighted imaging in the diagnosis of hypoxic-ischemic encephalopathy and kernicterus in premature infants

BACKGROUND

To explore the application of magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) in the diagnosis of hypoxic-ischemic encephalopathy and kernicterus in premature infants.

METHODS

Fifty-eight premature infants with hypoxic-ischemic encephalopathy and fifty-eight premature infants with kernicterus who were examined and treated in our hospital between January 2018 and January 2021 were assigned to the observation group or the control group. All patients were examined by MRI imaging and DWI imaging, and the examination results were compared between the two groups.

RESULTS

No significant differences were found in sensitivity, specificity, positive predictive value, or negative predictive value between the observation group and the control group (P>0.05). MRI could clearly visualize the signal changes of patients, whereas DWI did not show any signal changes. There was no significant difference between MRI and DWI in the diagnosis of hypoxic-ischemic encephalopathy in premature infants. Further, there was no significant difference in the diagnostic performance of MRI between the observation group and the control group (P>0.05). However, the diagnostic performance of DWI in the control group was better than that in the observation group, and the difference was statistically significant (P<0.05).

CONCLUSIONS

MRI and DWI imaging have high detection rates for the diagnosis of hypoxic-ischemic encephalopathy and kernicterus in premature infants. These imaging methods can benefit the treatment of premature infants and have important clinical application value.

Velamentous cord insertion, ischemic-hypoxic encephalopathy, and neurological rehabilitation: A case report

Hypoxic-ischemic encephalopathy is a frequent and important cause of neurological problems in term and preterm newborns. A sentinel event of this entity is the vasa previa, specifically when there is an abnormality of the placenta such as a velamentous cord insertion. Some reports have shown the association between these two entities, but those regarding the recovery process and the neurological prognosis of children with both conditions are scarce. We present the case of a patient with a history of velamentous cord insertion and hypoxicischemic encephalopathy who received therapeutic hypothermia (cool cap). We describe his neurological rehabilitation process and we calculated the percentage of probability of presenting this condition compared to the population without these factors. The patient was a five-year-old boy with an Apgar index at birth equal to zero at one minute and equal to two at fifteen minutes who developed severe hypoxic-ischemic encephalopathy secondary to a velamentous cord insertion without prenatal diagnosis and a marked initial neurological and multisystemic compromise. The recovery process included early multidisciplinary management in the neonatal intensive care unit and a focus on early neurological habilitation. The patient is currently in school and he undergoes comprehensive therapies; on physical examination, he presents no motor or sensory deficiencies. His neuropsychological test suggests the risk of attention deficit hyperactivity disorder. Children with severe hypoxicischemic encephalopathy usually have disabilities due to motor, cognitive, and/or behavioral deficiencies.

Acute Brain Injury in Infant Venoarterial Extracorporeal Membrane Oxygenation: An Autopsy Study

OBJECTIVES

Characterization of the types and timing of acute brain injury in infant autopsy patients after extracorporeal membrane oxygenation.

DESIGN

Retrospective cohort study.

SETTING

Single tertiary-care center.

PATIENTS

Infants supported on extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

Clinical and pathologic records were reviewed for infant extracorporeal membrane oxygenation patients who had undergone brain autopsy in a single center between January 2009 and December 2018. Twenty-four patients supported on venoarterial extracorporeal membrane oxygenation had postmortem examination with brain autopsy. Median age at extracorporeal membrane oxygenation initiation was 82 days (interquartile range, 11-263 d), median age at time of death was 20 weeks (interquartile range, 5-44 wk), and median extracorporeal membrane oxygenation support duration was 108 hours (interquartile range, 35-366 hr). The most common acute brain injury found at autopsy was hypoxic-ischemic brain injury (58%) followed by intracranial hemorrhage (29%). The most common types of intracranial hemorrhage were intracerebral (17%), subarachnoid (17%), and subdural (8%). Only five infants (21%) did not have acute brain injury. Correlates of acute brain injury included low preextracorporeal membrane oxygenation oxygen saturation as well as elevated liver enzymes, total bilirubin, and lactate on days 1 and 3 of extracorporeal membrane oxygenation. Gestational age, Apgar scores, birth weight, extracorporeal membrane oxygenation duration, anticoagulation therapy, and renal and hepatic impairments were not associated with acute brain injury.

CONCLUSIONS

Acute brain injury was observed in 79% of autopsies conducted in infants supported on extracorporeal membrane oxygenation. Hypoxic-ischemic brain injury was the most common type of brain injury (58%), and further associations with preextracorporeal membrane oxygenation acute brain injury require additional exploration.

Consensus protocol for EEG and amplitude-integrated EEG assessment and monitoring in neonates

The aim of this work is to establish inclusive guidelines on electroencephalography (EEG) applicable to all neonatal intensive care units (NICUs). Guidelines on ideal EEG monitoring for neonates are available, but there are significant barriers to their implementation in many centres around the world. These include barriers due to limited resources regarding the availability of equipment and technical and interpretive round-the-clock personnel. On the other hand, despite its limitations, amplitude-integrated EEG (aEEG) (previously called Cerebral Function Monitor [CFM]) is a common alternative used in NICUs. The Italian Neonatal Seizure Collaborative Network (INNESCO), working with all national scientific societies interested in the field of neonatal clinical neurophysiology, performed a systematic literature review and promoted interdisciplinary discussions among experts (neonatologists, paediatric neurologists, neurophysiologists, technicians) between 2017 and 2020 with the aim of elaborating shared recommendations. A consensus statement on videoEEG (vEEG) and aEEG for the principal neonatal indications was established. The authors propose a flexible frame of recommendations based on the complementary use of vEEG and aEEG applicable to the various neonatal units with different levels of complexity according to local resources and specific patient features. Suggestions for promoting cooperation between neonatologists, paediatric neurologists, and neurophysiologists, organisational restructuring, and teleneurophysiology implementation are provided.

Linking acute symptomatic neonatal seizures, brain injury and outcome in preterm infants

Neonatal seizures (NS) are the most frequent sign of neurological dysfunction in newborn infants. With increased survival of preterm neonates, the current clinical focus has shifted from preventing death to improving long-term neurological outcome. In the context of acute symptomatic NS, the main negative prognostic factors include etiology, and severity of brain injury, but also prolonged seizures and especially status epilepticus. However, the reasons for the detrimental contribution of seizures to outcome are still unclear, and evidence has been collected both in favor of seizures being an epiphenomenon of brain injury and of independently contributing to further damage. In this narrative focused review, we will discuss both hypotheses, with special emphasis on data relating to preterm infants. We will also identify present controversies and possible future lines of research.

Perinatal factors associated with amplitude-integrated electroencephalography abnormalities in preterm infants on the first day of life

OBJECTIVE

Evaluate the association between perinatal factors and amplitude-integrated electroencephalogram abnormalities in preterm infants on the first day of life.

METHODS

This was a cross-sectional study of 60 infants with gestational age between 23 and 32 weeks, without malformations. Infants were continuously monitored by amplitude-integrated electroencephalogram on the first day of life, for at least 3h. The tracings were recorded and analyzed in each column for the following: burst-suppression pattern, sleep-wake cycle, and amplitude of the lower margin (<3μV or <5μV). The association of maternal complications, mode of delivery, birth weight, gestational age, neonatal sex, resuscitation procedures, hypothermia on admission, and the Score for Neonatal Acute Physiology, Perinatal Extension, Version II [SNAPPE-II]) with amplitude-integrated electroencephalogram alterations was assessed by multiple logistic regression.

RESULTS

A discontinuous pattern occurred in 65% of infants, and a continuous pattern occurred in 23%. The burst-suppression pattern was associated with vaginal delivery (OR: 7.6; 95% CI: 1.1-53.1) and SNAPPE-II≥40 (OR: 13.1; 95% CI: 1.8-95.1). A lower margin of the amplitude-integrated electroencephalogram of <3μV was also associated with SNAPPE-II≥40 (OR: 10.6, 95% CI: 2.3-49.2), while a value <5μV was associated with lower GA (OR: 0.51, 95% CI: 0.34-0.76). There were no associations between the perinatal variables and the absence of a sleep-wake cycle in amplitude-integrated electroencephalogram recordings on the first day of life.

CONCLUSION

Biological variables and clinical severity are associated with electroencephalographic characteristics of preterm infants on the first day of life and should be considered in clinical practice when amplitude-integrated electroencephalogram is performed.

Cortical responses to tactile stimuli in preterm infants

The conventional assessment of preterm somatosensory functions using averaged cortical responses to electrical stimulation ignores the characteristic components of preterm somatosensory evoked responses (SERs). Our study aimed to systematically evaluate the occurrence and development of SERs after tactile stimulus in preterm infants. We analysed SERs performed during 45 electroencephalograms (EEGs) from 29 infants at the mean post-menstrual age of 30.7 weeks. Altogether 2,087 SERs were identified visually at single-trial level from unfiltered signals capturing also their slowest components. We observed salient SERs with a high-amplitude slow component at a high success rate after hand (95%) and foot (83%) stimuli. There was a clear developmental change in both the slow wave and the higher-frequency components of the SERs. Infants with intraventricular haemorrhage (IVH; eleven infants) had initially normal SERs, but those with bilateral IVH later showed a developmental decrease in the ipsilateral SER occurrence after 30 weeks of post-menstrual age. Our study shows that tactile stimulus applied at bedside elicits salient SERs with a large slow component and an overriding fast oscillation, which are specific to the preterm period. Prior experimental research indicates that such SERs allow studying both subplate and cortical functions. Our present findings further suggest that they might offer a window to the emergence of neurodevelopmental sequelae after major structural brain lesions and, hence, an additional tool for both research and clinical neurophysiological evaluation of infants before term age.

Outcome in preterm infants with seizures

Most neonatal seizures in preterm newborns are of acute symptomatic origin with a prevalence higher than in full-term infants. To date, recommendations for management of seizures in preterm newborns are scarce and do not differ from those in full-term newborns. Mortality in preterm newborns with seizures has significantly declined over the last decades, from figures of 84%-94% in the 1970s and 1980s to 22%-45% in the last years. However, mortality is significantly higher in those with a birth weight<1000g and a gestational age<28 weeks. Seizures are a strong predictor of unfavorable outcomes, including not only cerebral palsy, epilepsy, and intellectual disability, but also vision, hearing impairment, and microcephaly. The majority of patients with developmental delay are severely affected and this is usually associated with cerebral palsy. Furthermore, the incidence of epilepsy after neonatal seizures seems to be lower in preterm than in full-term infants but the risk is approximately 40 times greater than in the general population. Clinical studies cannot disentangle the specific and independent contributions of seizure-induced functional changes and the role of etiology and brain damage severity in determining the long-term outcomes in these newborns.

Accelerated Small-World Property of Structural Brain Networks in Preterm Infants at Term-Equivalent Age

BACKGROUND

The prediction of neurodevelopmental outcomes in preterm infants is one of the clinical challenges of pediatrics. Despite the recent interest in brain development and white matter connectivity using a network-based analysis, very little is known about the brain network of at term-equivalent age in preterm infants.

OBJECTIVE

We aimed to investigate the structural brain network using diffusion MRI following preterm delivery at term-equivalent age compared with term infants and explored the influence of gestational age (GA) and clinical factors.

METHOD

Diffusion tensor imaging data were acquired prospectively from 55 preterm neonates without apparent brain abnormalities (mean gestational age: 29.43 weeks) and 21 full-term infants at term-equivalent age. The global structural brain networks were produced by probabilistic white matter tractography in combination with the Johns Hopkins University neonate atlas to quantify connectivity between different cortical regions.

RESULTS

Compared with full-term infants, preterm infants had significantly lower global efficiency (p = 0.048) and increased small worldness (p = 0.012) after correcting for sex and age at MRI scan. The increased small worldness in the brain network at term-equivalent age was significantly linearly correlated with lower GA after adjusting for sex and the effects of postmenstrual age at MRI scan on the data in preterm infants (β = -0.020, p = 0.037). In multivariate analysis, infants with chronic lung disease had significantly decreased changes in clustering (p = 0.014) and local efficiency (p = 0.027).

CONCLUSION

The accelerated small worldness in preterm infants suggests that the structural brain network after preterm birth is reorganized in maximizing integrated and segregated processing, implying resilience against prematurity-associated pathology.

Symptomatic seizures in preterm newborns: a review on clinical features and prognosis

Neonatal seizures are the most common neurological event in newborns, showing higher prevalence in preterm than in full-term infants. In the majority of cases they represent acute symptomatic phenomena, the main etiologies being intraventricular haemorrhage, hypoxic-ischemic encephalopathy, central nervous system infections and transient metabolic derangements.Current definition of neonatal seizures requires detection of paroxysmal EEG-changes, and in preterm newborns the incidence of electrographic-only seizures seems to be particularly high, further stressing the crucial role of electroencephalogram monitoring in this population. Imaging work-up includes an integration of serial cranial ultrasound and brain magnetic resonance at term-equivalent age. Unfavourable outcomes following seizures in preterm infants include death, neurodevelopmental impairment, epilepsy, cerebral palsy, hearing and visual impairment. As experimental evidence suggests a detrimental role of seizures per se in determining subsequent outcome, they should be promptly treated with the aim to reduce seizure burden and long-term disabilities. However, neonatal seizures show low response to conventional anticonvulsant drugs, and this is even more evident in preterm newborns, due to intrinsic developmental factors. As a consequence, as literature does not provide any specific guidelines, due to the lack of robust evidence, off-label medications are often administered in clinical practice.

The Role of Kainate Receptors in the Pathophysiology of Hypoxia-Induced Seizures in the Neonatal Mouse

Kainate receptors (KARs) are glutamate receptors with peak expression during late embryonic and early postnatal periods. Altered KAR-mediated neurotransmission and subunit expression are observed in several brain disorders, including epilepsy. Here, we examined the role of KARs in regulating seizures in neonatal C57BL/6 mice exposed to a hypoxic insult. We found that knockout of the GluK2 subunit, or blockade of KARs by UBP310 reduced seizure susceptibility during the period of reoxygenation. Following the hypoxic insult, we observed an increase in excitatory neurotransmission in hippocampal CA3 pyramidal cells, which was blocked by treatment with UBP310 prior to hypoxia. Similarly, we observed increased excitatory neurotransmission in CA3 pyramidal cells in an in vitro hippocampal slice model of hypoxic-ischemia. This increase was absent in slices from GluK2^−/− mice and in slices treated with UBP310, suggesting that KARs regulate, at least in part, excitatory synaptic neurotransmission following in vivo hypoxia in neonatal mice. Data from these hypoxia models demonstrate that KARs, specifically those containing the GluK2 subunit, contribute to alterations in excitatory neurotransmission and seizure susceptibility, particularly during the reoxygenation period, in neonatal mice. Therapies targeting KARs may prove successful in treatment of neonates affected by hypoxic seizures.

Sleep-wake cycle on amplitude-integrated EEG and neuroimage outcomes in newborns

BACKGROUND

The aim of this study was to evaluate the results of sleep-wake cycle monitoring using amplitude-integrated EEG (aEEG) and neuroimaging in newborn infants with a possible perinatal hypoxic insult, investigate the correlation between the findings, and determine the relevance of the findings to reasonably predict neurological outcome.

METHODS

aEEG was recorded among newborn infants suspected of perinatal asphyxia between November, 2014 and June, 2015 in one neonatal intensive care unit facility. Brain imaging with serial ultrasonography and MRI when available were performed, and the infants were divided into two groups according to findings and potential neurological outcome: Group I (favorable findings) and Group II (severe findings such as high grade intraventricular hemorrhage, cerebral infarction or white matter injury). Established sleep-wake cycle times after birth was compared between the two groups.

RESULTS

Among 107 newborn infants, 85 subjects were classified as Group I and the remaining 22 subjects as Group II. The total number of aEEG sessions was 207 and recording time was 2,796 h with a mean of 14.43 ± 13.40 h per study. Estimated times of cyclicity were earlier in Group I (113.34 h, 95 % CI 82.31-144.37) as compared to Group II (504.39 h, 95 % CI 319.91-688.88; p < 0.001).

CONCLUSIONS

Delayed cyclicity on aEEG has a strong correlation with unfavorable brain neuroimages in newborns with possible perinatal asphyxia. If sleep-wake cycles do not appear during initial period after birth, follow-up aEEG studies are recommended.

TRIAL REGISTRATION

Retrospectively registered Registration number: BD 2015-148 Name of registry: amplitude integrated EEG in neonate Date of registration: September 9, 2015.