Update on the current management of newborns with neonatal encephalopathy

Regional variability in therapeutic hypothermia eligibility criteria for neonatal hypoxic-ischemic encephalopathy

Early induced therapeutic hypothermia represents the cornerstone treatment in neonates with probable hypoxic-ischemic encephalopathy. The selection of patients for treatment usually involves meeting criteria indicating evidence of perinatal hypoxia-ischemia and the presence of moderate or severe encephalopathy. In this review, we highlight the variability that exists between some of the different regional and national eligibility guidelines. Determining the potential presence of perinatal hypoxia-ischemia may require either one, two or three signs amongst history of acute perinatal event, prolonged resuscitation at delivery, abnormal blood gases and low Apgar score, with a range of cutoff values. Clinical neurological exams often define the severity of encephalopathy differently, with varying number of domains required for determining eligibility and blurred interpretation of findings assigned to different severity grades in different systems. The role of early electrophysiological assessment is weighted differently. A clinical implication is that infants may receive different care depending on the location in which they are born. This could also impact epidemiological data, as inference of rates of moderate-severe encephalopathy based on therapeutic hypothermia rates are misleading and influenced by different eligibility methods used. We would advocate that a universally endorsed single severity staging of encephalopathy is vital for standardizing management and neonatal outcome. IMPACT: Variability exists between regional and national therapeutic hypothermia eligibility guidelines for neonates with probable hypoxic-ischemic encephalopathy. Differences are common in both criteria indicating perinatal hypoxia-ischemia and criteria defining moderate or severe encephalopathy. The role of early electrophysiological assessment is also weighted unequally. This reflects in different individual care and impacts research data. A universally endorsed single severity staging of encephalopathy would be crucial for standardizing management.

Enhanced Markerless Tracking of Infant General Movements in Standard Videos Through Lightning Pose Compared to DeepLabCut

Monitoring abnormal or absent General Movements (GMs) in infants between 6-20 weeks post-term age serves as a reliable prognostic tool for assessing neurodevelopmental quality and determining the risk of neurological impairments, such as cerebral palsy (CP), in early infancy. Early therapeutic interventions during this timeframe are most effective due to the brain's plasticity. Building on our previous work, this paper compares the reliability and applicability of the Lightning Pose (LP) platform to our prior attempts using the DeepLabCut (DLC) environment for the reliable markerless pose-estimation and tracking of infants' anatomical landmarks in clinically recorded videos from handheld devices (e.g., iPads). Here, we specifically compare the capabilities of Resnet-152, trained in both platforms, for identifying a novel clinically useful set of 24 anatomical landmarks across a comprehensive unseen set of video frames, tracking a baby's natural movement during validation recordings. Using our novel unsupervised performance assessment algorithm on over 3200 unseen frames from two full-term male infants, we show that LP outperforms DLC in body parts identification, achieving 99.75% accuracy compared to DLC's 97.80%, despite nearly identical training sets extracted by both algorithms (average cosine similarity index of 0.95).Clinical relevance-The superior performance of LP in this study represents a significant stride toward developing a cost-effective and widely accessible technology for automatically monitoring of infants' GMs and identifying those at elevated risk of developing neurological conditions in early infancy.

Comparison of Different Adjuvant Therapies for Hypothermia in Neonates with Hypoxic-Ischemic Encephalopathy: A Systematic Review and Network Meta-Analysis

OBJECTIVES

Neonatal hypoxic-ischemic encephalopathy is a major cause of perinatal death and neurodevelopmental impairment (NDI). Hypothermia (HT) is the standard of care; however, additional neuroprotective agents are required to improve prognosis. The authors searched for all drugs in combination with HT and compared their effects using a network meta-analysis.

METHODS

The authors searched PubMed, Embase, and Cochrane Library until September 24, 2022 for articles assessing mortality, NDI, seizures, and abnormal brain imaging findings in neonates with hypoxic-ischemic encephalopathy. Direct pairwise comparisons and a network meta-analysis was performed under random effects.

RESULTS

Thirteen randomized clinical trials enroled 902 newborns treated with six combination therapies: erythropoietin magnesium sulfate, melatonin (MT), topiramate, xenon, and darbepoetin alfa. The results of all comparisons were not statistically significant, except for NDI, HT vs. MT+HT: odds ratio = 6.67, 95% confidence interval = 1.14-38.83; however, the overall evidence quality was low for the small sample size.

CONCLUSIONS

Currently, no combination therapy can reduce mortality, seizures, or abnormal brain imaging findings in neonatal hypoxic-ischemic encephalopathy. According to low quality evidence, HT combined with MT may reduce NDI.

Necroptosis Blockade Potentiates the Neuroprotective Effect of Hypothermia in Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal encephalopathy (NE) caused by hypoxia-ischemia (HI) affects around 1 per 1000 term newborns and is the leading cause of acquired brain injury and neurodisability. Despite the use of hypothermia (HT) as a standard of care, the incidence of NE and its devastating outcomes remains a major issue. Ongoing research surrounding add-on neuroprotective strategies against NE is important as HT effects are limited, leaving 50% of treated patients with neurological sequelae. Little is known about the interaction between necroptotic blockade and HT in neonatal HI. Using a preclinical Lewis rat model of term human NE induced by HI, we showed a neuroprotective effect of Necrostatin-1 (Nec-1: a compound blocking necroptosis) in combination with HT. The beneficial effect of Nec-1 added to HT against NE injuries was observed at the mechanistic level on both pMLKL and TNF-α, and at the anatomical level on brain volume loss visualized by magnetic resonance imaging (MRI). HT alone showed no effect on activated necroptotic effectors and did not preserve the brain MRI volume. This study opens new avenues of research to understand better the specific cell death mechanisms of brain injuries as well as the potential use of new therapeutics targeting the necroptosis pathway.

Neurovascular responses to neuronal activity during sensory development

Understanding the development of intercellular communication in sensory regions is relevant to elucidate mechanisms of physiological and pathological responses to oxygen shortage in the newborn brain. Decades of studies in laboratory rodents show that neuronal activity impacts sensory maturation during two periods of postnatal development distinguished by the maturation of accessory structures at the sensory periphery. During the first of these developmental periods, angiogenesis is modulated by neuronal activity, and physiological levels of neuronal activity cause local tissue hypoxic events. This correlation suggests that neuronal activity is upstream of the production of angiogenic factors, a process that is mediated by intermittent hypoxia caused by neuronal oxygen consumption. In this perspective article we address three theoretical implications based on this hypothesis: first, that spontaneous activity of sensory neurons has properties that favor the generation of intermittent tissue hypoxia in neonate rodents; second, that intermittent hypoxia promotes the expression of hypoxia inducible transcription factors (HIFs) in sensory neurons and astrocytes; and third, that activity-dependent production of angiogenic factors is involved in pathological oxygen contexts.

Challenges in the application of non-servocontrolled therapeutic hypothermia during neonatal transport in Catalonia

INTRODUCTION

Therapeutic hypothermia (TH) improves survival and neurological prognosis in hypoxic-ischemic encephalopathic (HIE) babies, being better the sooner TH is implemented. HIE babies are born more frequently in a non-cooling centre and need to be referred.

METHODS

Prospective-observational study (April 18 2018 - November 19 2019). Newborns (≥34 weeks of gestational age (GA) and >1800 g) with moderate/severe HIE on non-servocontrolled therapeutic hypothermia by the two neonatal transport teams in Catalonia.

RESULTS

51 newborns. The median stabilisation and transport time were 68 min (p25-75, 45-85 min) and 30 min (p25-75, 15-45 min), respectively. The mean age at arrival at the receiving unit was 4 h and 18 min (SD 96.6). The incubator was set off in 43 (84%), iced-packs 11 (21.5%) and both (11, 21.5%). Target temperature was reached in 19 (37.3%) babies. There were no differences in the overcooling in relation to the measures applied. The transport duration was not related with temperature stabilisation or target temperature reachiness.

CONCLUSIONS

Rectal temperature monitorisation is compulsory for the stabilisation and the application of non-servocontrolled hypothermia during transport. There is still time for improving in the administration of this treatment during transport. Servo-controlled hypothermia would be a better alternative to improve the management of HIE babies.

[Challenges in the application of non-servocontrolled therapeutic hypothermia during neonatal transport in Catalonia]

INTRODUCTION

Therapeutic hypothermia (TH) improves survival and neurological prognosis in hypoxic-ischemic encephalopathic (HIE) babies, being better the sooner TH is implemented. HIE babies are born more frequently in a non-cooling centre and need to be referred.

METHODS

Prospective-observational study (April 18-November 19). Newborns (≥34 weeks of gestational age (GA) and >1800g) with moderate/severe HIE on non-servocontrolled therapeutic hypothermia by the two neonatal transport teams in Catalonia.

RESULTS

51 newborns. The median stabilisation and transport time were 68min (p25-75, 45-85min) and 30min (p25-75, 15-45min), respectively. The mean age at arrival at the receiving unit was 4h and 18min (SD 96.6). The incubator was set off in 43 (84%), iced-packs 11 (21.5%) and both (11, 21.5%). Target temperature was reached in 19 (37.3%) babies. There was no differences in the overcooling in relation to the measures applied. The transport duration was not related with temperature stabilisation or target temperature reachiness.

CONCLUSIONS

Rectal temperature monitorisation is compulsory for the stabilisation and the application of non-servocontrolled hypothermia during transport. There is still time for improving in the administration of this treatment during transport. Servo-controlled hypothermia would be a better alternative to improve the management of HIE babies.

Neuroprotection of N-benzyl Eicosapentaenamide in Neonatal Mice Following Hypoxic-Ischemic Brain Injury

Maca (Lepidium meyenii) has emerged as a popular functional plant food because of its medicinal properties and nutritional value. Macamides, as the exclusively active ingredients found in maca, are a unique series of non-polar, long-chain fatty acid N-benzylamides with multiple bioactivities such as antifatigue characteristics and improving reproductive health. In this study, a new kind of macamide, N-benzyl eicosapentaenamide (NB-EPA), was identified from maca. We further explore its potential neuroprotective role in hypoxic–ischemic brain injury. Our findings indicated that treatment with biosynthesized NB-EPA significantly alleviates the size of cerebral infarction and improves neurobehavioral disorders after hypoxic–ischemic brain damage in neonatal mice. NB-EPA inhibited the apoptosis of neuronal cells after ischemic challenge. NB-EPA improved neuronal cell survival and proliferation through the activation of phosphorylated AKT signaling. Of note, the protective property of NB-EPA against ischemic neuronal damage was dependent on suppression of the p53–PUMA pathway. Taken together, these findings suggest that NB-EPA may represent a new neuroprotectant for newborns with hypoxic–ischemic encephalopathy.

Acrobatic exercise recovers object recognition memory impairment in hypoxic-ischemic rats

Neonatal hypoxia-ischemia (HI) can lead to cognitive impairments and motor dysfunction. Acrobatic exercises (AE) were proposing as therapeutic option to manage HI motor deficits, however, the cognitive effects after this treatment are still poorly understood. Therefore, we evaluated the effects of AE protocol on memory impairments and brain plasticity markers after Rice-Vannucci HI rodent model. Wistar rats on the 7th postnatal day (PND) were submitted to HI model and after weaning (PND22) were trained for 5 weeks with AE protocol, then subsequently submitted to cognitive tests. Our results showed recovery in novel object recognition (NOR) memory, but not, spatial Morris Water Maze (WM) memory after AE treatment in HI rats. BDNF and synaptophysin neuroplasticity markers indicate plastic alterations in the hippocampus and striatum, with maintenance of synaptophysin despite the reduction of total volume tissue, besides, hippocampal HI-induced ipsilateral BDNF increased, and striatum contralateral BDNF decreased were noted. Nevertheless, the exercise promoted functional recovery and seems to be a promising strategy for HI treatment, however, future studies identifying neuroplastic pathway for this improvement are needed.

Spectral-domain OCT changes in retina and optic nerve in children with hypoxic-ischaemic encephalopathy

Purpose

To evaluate the effect of neonatal hypoxic–ischaemic injury on the retina and the optic nerve and to correlate ocular damage with systemic parameters, laboratory tests, neurological imaging and therapeutic hypothermia at birth.

Methods

Forty-one children with hypoxic–ischaemic encephalopathy (HIE) at birth (9.09 ± 3.78 years) and a control group of 38 healthy subjects (9.57 ± 3.47 years) were enrolled in a cohort study. The HIE population was divided into three subgroups, based on the degree of encephalopathy according to Sarnat score and the treatment with therapeutic hypothermia (TH): Sarnat score I not treated with hypothermia, Sarnat score II-III treated with TH and Sarnat score II-III not subjected to TH. Total macular thickness, individual retinal layers and peripapillary nerve fibre layer thickness were measured with spectral-domain optical coherence tomography. Clinical data of perinatal period of HIE children were collected: APGAR score, pH and base excess of funiculus blood at birth, apnoea duration, brain ultrasound, cerebral MRI ischaemic lesions and blood chemistry tests.

Results

Children with Sarnat score I did not show a reduction of peripapillary nerve fibres and ganglion cell layer compared to the control group (p = 0.387, p = 0.316). Peripapillary nerve fibre layer was 109.06 ± 7.79 μm in children with Sarnat score II-III treated with TH, 108.31 ± 7.83 μm in subjects with Sarnat score II-III not subjected to TH and 114.27 ± 6.81 μm in the control group (p = 0.028, p = 0.007). Ganglion cell layer was thinner in children with Sarnat score II-III treated with TH (50.31 ± 5.13 μm) compared to the control group (54.04 ± 2.81 μm) (p = 0.01). Inner retinal layers damage correlated with C-reactive protein and lactate dehydrogenase increase, while higher levels of total bilirubin were protective against retinal impairment (p < 0.05). Cerebral oedema was related to peripapillary nerve fibre layer damage (p = 0.046).

Conclusions

Thickness reduction of inner retinal layer and peripapillary nerve fibre impairment was related to encephalopathy severity. Ocular damage was associated with inflammation and cerebral oedema following hypoxic–ischaemic damage.

Cap-Based Transcranial Optical Tomography in an Awake Infant

Although Blood Oxygenation Level Dependent (BOLD) functional MRI (fMRI) is widely used to examine brain function in adults, the need for general anesthesia limits its practical utility in infants and small children. Functional Near-Infrared Spectroscopy - Diffuse Optical Tomography (fNIRS-DOT) imaging promises to be an alternative brain network imaging technique. Yet current versions of continuous-wave fNIRS-DOT systems are restricted to the cortical surface measurements and do not probe deep structures that are frequently injured especially in premature infants. Herein we report a transcranial near infrared optical imaging system, called Cap-based Transcranial Optical Tomography (CTOT) able to image whole brain hemodynamic activity with 3 seconds of data acquisition time. We show the system is capable of whole brain oxygenation mapping in an awake child, and that tomographically reconstructed static CTOT-derived oxy- and deoxygenated blood volumes are spatially correlated with the time-averaged BOLD fMRI volumes. By removing time bottlenecks in the current system, dynamic CTOT mapping should be possible, which would then enable evaluation of functional connectivity in awake infants.

Neuroprotective effect of astrocyte-derived IL-33 in neonatal hypoxic-ischemic brain injury

Background

Interleukin-33 (IL-33) is a well-recognized pleiotropic cytokine which plays crucial roles in immune regulation and inflammatory responses. Recent studies suggest that IL-33 and its receptor ST2 are involved in the pathogenesis of neurological diseases. Here, we explore the effect of IL-33/ST2 signaling in neonatal hypoxic-ischemic (HI) brain injury and elucidate the underlying mechanisms of action.

Methods

The brain HI model was established in neonatal C57BL/6 mice by left common carotid artery occlusion with 90 min hypoxia and treated with IL-33 at a dose of 0.2 μg/day i.p. for 3 days. TTC staining and neurobehavioral observation were used to evaluate the HI brain injury. Immunofluorescence and flow cytometry were applied to determine the expression of IL-33 and its receptor ST2 on brain CNS cells and cell proliferation and apoptosis. OGD experiment was used to assay the viability of astrocytes and neurons. RT-qPCR was used to measure the expression of neurotrophic factor-associated genes.

Results

The expression level of IL-33 was markedly enhanced in astrocytes 24 h after cerebral HI in neonatal mice. Exogenous delivery of IL-33 significantly alleviated brain injury 7 days after HI, whereas ST2 deficiency exacerbated brain infarction and neurological deficits post HI. Flow cytometry analyses demonstrated high levels of ST2 expression on astrocytes, and the expression of ST2 was further elevated after HI. Intriguingly, IL-33 treatment apparently improved astrocyte response and attenuated HI-induced astrocyte apoptosis through ST2 signaling pathways. Further in vitro studies revealed that IL-33-activated astrocytes released a series of neurotrophic factors, which are critical for raising neuronal survival against oxygen glucose deprivation.

Conclusions

The activation of IL-33/ST2 signaling in the ischemic brain improves astrocyte response, which in turn affords protection to ischemic neurons in a glial-derived neurotrophic factor-dependent manner.