Safety and efficacy of topiramate in neonates with hypoxic ischemic encephalopathy treated with hypothermia (NeoNATI)

Targeting the Multiple Complex Processes of Hypoxia-Ischemia to Achieve Neuroprotection

Hypoxic-ischemic encephalopathy (HIE) is a major cause of newborn brain damage stemming from a lack of oxygenated blood flow in the neonatal period. Twenty-five to fifty percent of asphyxiated infants who develop HIE die in the neonatal period, and about sixty percent of survivors develop long-term neurological disabilities. From the first minutes to months after the injury, a cascade of events occurs, leading to blood-brain barrier (BBB) opening, neuronal death and inflammation. To date, the only approach proposed in some cases is therapeutic hypothermia (TH). Unfortunately, TH is only partially protective and is not applicable to all neonates. This review synthesizes current knowledge on the basic molecular mechanisms of brain damage in hypoxia-ischemia (HI) and on the different therapeutic strategies in HI that have been used and explores a major limitation of unsuccessful therapeutic approaches.

Analgesia and sedation strategies in neonates undergoing whole-body therapeutic hypothermia: A scoping review

BACKGROUND

Therapeutic hypothermia (TH) is a widely practiced neuroprotective strategy for neonates with hypoxic-ischemic encephalopathy. Induced hypothermia is associated with shivering, cold pain, agitation, and distress.

OBJECTIVE

This scoping review determines the breadth of research undertaken for pain and stress management in neonates undergoing hypothermia therapy, the pharmacokinetics of analgesic and sedative medications during hypothermia and the effect of such medication on short- and long-term neurological outcomes.

METHODS

We searched the following online databases namely, (i) MEDLINE, (ii) Web of Science, (iii) Cochrane Library, (iv) Scopus, (v) CINAHL, and (vi) EMBASE to identify published original articles between January 2005 and December 2022. We included only English full-text articles on neonates treated with TH and reported the sedation/analgesia strategy used. We excluded articles that reported TH on transport or extracorporeal membrane oxygenation, did not report the intervention strategies for sedation/analgesia, and reported hypoxic-ischemic encephalopathy in which hypothermia was not applied.

RESULTS

The eligible publications (n = 97) included cohort studies (n = 72), non-randomized experimental studies (n = 2), pharmacokinetic studies (n = 4), dose escalation feasibility trial (n = 1), cross-sectional surveys (n = 5), and randomized control trials (n = 13). Neonatal Pain, Agitation, and Sedation Scale (NPASS) is the most frequently used pain assessment tool in this cohort. The most frequently used pharmacological agents are opioids (Morphine, Fentanyl), benzodiazepine (Midazolam) and Alpha2 agonists (Dexmedetomidine). The proportion of neonates receiving routine sedation-analgesia during TH is center-specific and varies from 40-100% worldwide. TH alters most drugs' metabolic rate and clearance, except for Midazolam. Dexmedetomidine has additional benefits of thermal tolerance, neuroprotection, faster recovery, and less likelihood of seizures. There is a wide inter-individual variability in serum drug levels due to the impact of temperature, end-organ dysfunction, postnatal age, and body weight on drug metabolism.

CONCLUSIONS

No multidimensional pain scale has been tested for reliability and construct validity in hypothermic encephalopathic neonates. There is an increasing trend towards using routine sedation/analgesia during TH worldwide. Wide variability in the type of medication used, administration (bolus versus infusion), and dose ranges used emphasizes the urgent need for standardized practice recommendations and guidelines. There is insufficient data on the long-term neurological outcomes of exposure to these medications, adjusted for underlying brain injury and severity of encephalopathy. Future studies will need to develop framework tools to enable precise control of sedation/analgesia drug exposure customized to individual patient needs.

Advances in Therapies to Treat Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxic-ischemic encephalopathy (HIE) is a condition that results in brain damage in newborns due to insufficient blood and oxygen supply during or after birth. HIE is a major cause of neurological disability and mortality in newborns, with over one million neonatal deaths occurring annually worldwide. The severity of brain injury and the outcome of HIE depend on several factors, including the cause of oxygen deprivation, brain maturity, regional blood flow, and maternal health conditions. HIE is classified into mild, moderate, and severe categories based on the extent of brain damage and resulting neurological issues. The pathophysiology of HIE involves different phases, including the primary phase, latent phase, secondary phase, and tertiary phase. The primary and secondary phases are characterized by episodes of energy and cell metabolism failures, increased cytotoxicity and apoptosis, and activated microglia and inflammation in the brain. A tertiary phase occurs if the brain injury persists, characterized by reduced neural plasticity and neuronal loss. Understanding the cellular and molecular aspects of the different phases of HIE is crucial for developing new interventions and therapeutics. This review aims to discuss the pathophysiology of HIE, therapeutic hypothermia (TH), the only approved therapy for HIE, ongoing developments of adjuvants for TH, and potential future drugs for HIE.

Therapeutic hypothermia in neonatal hypoxic encephalopathy: A systematic review and meta-analysis

Background

Therapeutic hypothermia (TH) is regarded as the most efficacious therapy for neonatal hypoxic encephalopathy. However, limitations in previous systematic reviews and the publication of new data necessitate updating the evidence. We conducted this up-to-date systematic review to evaluate the effects of TH in neonatal encephalopathy on clinical outcomes.

Methods

In this systematic review and meta-analysis, we searched Medline, Cochrane Library, Embase, LIVIVO, Web of Science, Scopus, CINAHL, major trial registries, and grey literature (from inception to October 31, 2021), for randomized controlled trials (RCT) comparing TH vs normothermia in neonatal encephalopathy. We included RCTs enrolling neonates (gestation ≥35 weeks) with perinatal asphyxia and encephalopathy, who received either TH (temperature ≤34°C) initiated within 6 hours of birth for ≥48 hours, vs no cooling. We excluded non-RCTs, those with delayed cooling, or cooling to >34°C. Two authors independently appraised risk-of-bias and extracted data on mortality and neurologic disability at four time points: neonatal (from randomization to discharge/death), infancy (18-24 months), childhood (5-10 years), and long-term (>10 years). Other outcomes included seizures, EEG abnormalities, and MRI findings. Summary data from published RCTs were pooled through fixed-effect meta-analysis.

Results

We identified 36 863 citations and included 39 publications representing 29 RCTs with 2926 participants. Thirteen studies each had low, moderate, and high risk-of-bias. The pooled risk ratios (95% confidence interval, CI) were as follows: neonatal mortality: 0.87 (95% CI = 0.75, 1.00), n = 2434, I² = 38%; mortality at 18-24 months: 0.88 (95% CI = 0.78, 1.01), n = 2042, I² = 51%; mortality at 5-10 years: 0.81 (95% CI = 0.62, 1.04), n = 515, I² = 59%; disability at 18-24 months: 0.62 (95% CI = 0.52, 0.75), n = 1440, I² = 26%; disability at 5-10 years: 0.68 (95% CI = 0.52, 0.90), n = 442, I² = 3%; mortality or disability at 18-24 months: 0.78 (95% CI = 0.72, 0.86), n = 1914, I² = 54%; cerebral palsy at 18-24 months: 0.63 (95% CI = 0.50, 0.78), n = 1136, I² = 39%; and childhood cerebral palsy: 0.63 (95% CI = 0.46, 0.85), n = 449, I² = 0%. Some outcomes showed significant differences by study-setting; the risk ratio (95% CI) for mortality at 18-24 months was 0.79 (95% CI = 0.66,0.93), n = 1212, I² = 7% in high-income countries, 0.67 (95% CI = 0.41, 1.09), n = 276, I² = 0% in upper-middle-income countries, and 1.18 (95% CI = 0.94, 1.47), n = 554, I² = 75% in lower-middle-income countries. The corresponding pooled risk ratios for ‘mortality or disability at 18-24 months’ were 0.77 (95% CI = 0.69, 0.86), n = 1089, I² = 0%; 0.56 (95% CI = 0.41, 0.78), n = 276, I² = 30%; and 0.92 (95% CI = 0.77, 1.09), n = 549, I² = 86% respectively. Trials with low risk of bias showed risk ratio of 0.97 (95% CI = 0.80, 1.16, n = 1475, I² = 62%) for neonatal mortality, whereas trials with higher risk of bias showed 0.71 (95% CI = 0.55, 0.91), n = 959, I² = 0%. Likewise, risk ratio for mortality at 18-24 months was 0.96 (95% CI = 0.83, 1.13), n = 1336, I² = 58% among low risk-of-bias trials, but 0.72 (95% CI = 0.56, 0.92), n = 706, I² = 0%, among higher risk of bias trials.

Conclusions

Therapeutic hypothermia for neonatal encephalopathy reduces neurologic disability and cerebral palsy, but its effect on neonatal, infantile and childhood mortality is uncertain. The setting where it is implemented affects the outcomes. Low(er) quality trials overestimated the potential benefit of TH.

Dedifferentiated human umbilical cord mesenchymal stem cell reprogramming of endogenous hSDF-1α expression participates in neural restoration in hypoxic-ischemic brain damage rats

The transplantation of human umbilical cord mesenchymal stem cells (hUC-MSCs) can promote hypoxic-ischemic brain damage (HIBD) nerve repair, but finding suitable seed cells to optimize transplantation and improve treatment efficiency is an urgent problem to be solved. In this study, we induced hUC-MSCs into dedifferentiated hUC-MSCs (De-hUC-MSCs), and the morphology, stem cell surface markers, proliferation and tri-directional differentiation ability of the De-hUC-MSCs and hUC-MSCs were detected. A whole-gene chip was utilized for genome cluster, gene ontology and KEGG pathway analyses of differentially expressed genes. De-hUC-MSCs were transplanted into HIBD rats, and behavioral experiments and immunofluorescence assays were used to assess the therapeutic effect. A lentivirus vector for human stromal cell-derived factor-1 (hSDF-1α) was constructed, and the role of hSDF-1α in the neuroprotective effect and mechanism of De-hUC-MSCs was verified. De-hUC-MSCs displayed similar cell morphology, stem cell surface marker expression, cell proliferation and even three-dimensional differentiation ability as hUC-MSCs but exhibited greater treatment potential in vivo. The reprogramming mechanism of hSDF-1α participated in the dedifferentiation process. By successfully constructing a stable hSDF-1α cell line, we found that De-hUC-MSCs might participate in nerve repair through the hSDF-1α/CXCR4/PI3K/Akt pathway. De-hUC-MSCs reprogramming of endogenous hSDF-1α expression may mediate the hSDF-1α/CXCR4/PI3K/Akt pathway involved in nerve repair in HIBD rats.

Neuroprotection Strategies for Term Encephalopathy

Brain injury in the full-term and near-term neonates is a significant cause of mortality and long-term morbidity, resulting in injury patterns distinct from that seen in premature infants and older patients. Therapeutic hypothermia improves long-term outcomes for many of these infants, but there is a continued search for therapies to enhance the plasticity of the newborn brain, resulting in long-term repair. It is likely that a combination strategy utilizing both early and late interventions may have the most benefit, capitalizing on endogenous mechanisms triggered by hypoxia or ischemia. Optimizing care of these critically ill newborns in the acute setting is also vital for improving both short- and long-term outcomes.

Recent advances in perinatal neuroprotection

Perinatal brain injury is a major cause of neurological disability in both premature and term infants. In this review, we summarize the evidence behind some established neuroprotective practices such as administration of antenatal steroids, intrapartum magnesium for preterm delivery, and therapeutic hypothermia. In addition, we examine emerging practices such as delayed cord clamping, postnatal magnesium administration, recombinant erythropoietin, and non-steroidal anti-inflammatory agents and finally inform the reader about novel interventions, some of which are currently in trials, such as xenon, melatonin, topiramate, allopurinol, creatine, and autologous cord cell therapy.

A correction formula for neuron-specific enolase measurement in hemolyzed neonatal serum samples

As a specific biomarker in neonatal hypoxic-ischemic encephalopathy (HIE), the measurement of neuron-specific enolase (NSE) has been advocated as a predictor of outcome in neurological injury. However, the measured levels of NSE may be influenced by hemolysis. In the current study, the change in the concentration of NSE in serum was measured by chemiluminescence prior to and following the addition of individual frozen and thawed red blood cells from 86 neonates that were collected within 24 h of birth. The changes in the concentration of NSE were compared with the changes in the concentration of hemoglobin (Hb), measured by the hemoglobin cyanide (HiCN) method, to establish a correction formula. The performance of the correction formula was evaluated by comparing the corrected concentration of NSE using the individual constants and the correction formula. The average individual constant of NSE from the 86 hemolyzed neonatal serum samples was 25.15±3.94 mg/g Hb. The concentration variation between NSE and Hb in neonatal sera could be described by the equation ΔNSE_serum=1.8594+24.0670 xΔHb_HiCN (r²=0.8045, P<0.001). There was no statistically significant difference in the NSE corrected results between the individual constant group and the correction formula group (Z=-1.645, P=0.100). The linear regression formula of Hb measured with the instrumental method compared with the HiCN method was Hb_instr=0.9816×Hb_HiCN+0.5596 (r²=0.9924, P<0.001). Based on these regression analyses, the correction formula for NSE in hemolyzed neonatal serum was determined as NSE_corr=NSE_meas-24.0670×Hb_HiCN-1.8594 or NSE_corr=NSE_meas-24.5181×Hb_instr+11.8609. In conclusion, hemolysis has a substantial influence on the accurate measurement of NSE in neonatal serum samples. For hemolyzed neonatal serum samples, correcting the NSE results using a correction formula is essential to evaluate the severity of neonatal hypoxic ischemic encephalopathy.

Safety and efficacy of topiramate in neonates with hypoxic ischemic encephalopathy treated with hypothermia (NeoNATI): a feasibility study

PURPOSE

To investigate the feasibility of a study based on treatment with topiramate (TPM) added to moderate hypothermia in newborns with hypoxic ischemic encephalopathy (HIE).

MATERIALS AND METHODS

Multicenter randomized controlled trial. Term newborns with precocious metabolic, clinical and electroencephalographic (EEG) signs of HIE were selected according to their amplified integrated EEG pattern and randomized to receive either TPM (10 mg/kg once a day for the first three days of life) plus moderate hypothermia or hypothermia alone. Safety was assessed by monitoring cardiorespiratory parameters and blood samples collected to check renal, liver, metabolic balance and TPM pharmacokinetics. Efficacy was evaluated by the combined frequency of mortality and severe neurological disability as primary outcome. Incidence of magnetic resonance injury, epilepsy, blindness, hearing loss, neurodevelopment at 18-24 months of life was assessed as secondary outcomes.

RESULTS

Forty-four asphyxiated newborns were enrolled in the study. Twenty one newborns (10 with moderate and 11 with severe HIE) were allocated to hypothermia plus TPM and 23 (12 moderate and 11 severe HIE) to hypothermia. No statistically or clinically significant differences were observed for safety, primary or secondary outcomes. However, a reduction in the prevalence of epilepsy was observed in newborns co-treated with TPM.

CONCLUSIONS

Results of this pilot trial suggest that administration of TPM in newborns with HIE is safe but does not reduce the combined frequency of mortality and severe neurological disability. The role of TPM co-treatment in preventing subsequent epilepsy deserves further studies.

Drugs for neuroprotection after birth asphyxia: Pharmacologic adjuncts to hypothermia

An adverse outcome is still encountered in 45% of full-term neonates with perinatal asphyxia who are treated with moderate hypothermia. At present pharmacologic therapies are developed to be added to hypothermia. In the present article, these potential neuroprotective interventions are described based on the molecular pathways set in motion during fetal hypoxia and following reoxygenation and reperfusion after birth. These pathways include excessive production of excitotoxins with subsequent over-stimulation of NMDA receptors and calcium influx in neuronal cells, excessive production of reactive oxygen and nitrogen species, activation of inflammation leading to inappropriate apoptosis, and loss of neurotrophic factors. Possibilities for pharmacologic combination therapy, where each drug will be administered based on the optimal point of time in the cascade of destructive molecular reactions, may further reduce brain damage due to perinatal asphyxia.

Neuroprotective agents for neonatal hypoxic-ischemic brain injury

Hypoxic-ischemic (H-I) brain injury in newborns is a major cause of morbidity and mortality that claims thousands of lives each year. In this review, we summarize the promising neuroprotective agents tested on animal models and pilot clinical studies of neonatal H-I brain injury according to the different phases of the disease. These agents target various phases of injury including the early phase of excitotoxicity, oxidative stress and apoptosis as well as late-phase inflammatory reaction and neural repair. We analyze the cell survival and cell death pathways modified by these agents in neonatal H-I brain injury. We aim to 'build a bridge' between animal trials of neuroprotective agents and potential candidate treatments for future clinical applications against H-I encephalopathy.

Short-term use of antiepileptic drugs is neurotoxic to the immature brain

Previous studies have shown that the long-term use of antiepileptic drugs can cause nervous system damage. However, short-term antiepileptic drug treatment is frequently given to infants, especially neonates, to control seizure. Whether the short-term use of antiepileptic drugs is neurotoxic remains unclear. In the present study, immature rats, 3–21 days of age, were intraperitoneally injected with phenobarbital and/or topiramate for 3 consecutive days. Hematoxylin-eosin and immunohistochemical staining revealed that phenobarbital and topiramate, individually or in combination, were cytotoxic to hippocampal CA1 neurons and inhibited the expression of GluR1 and NR2B, excitatory glutamate receptor subunits. Furthermore, the combination of the two drugs caused greater damage than either drug alone. The results demonstrate that the short-term use of antiepileptic drugs damages neurons in the immature brain and that the combined use of antiepileptic drugs exacerbates damage. Our findings suggest that clinicians should consider the potential neurotoxic risk associated with the combined use of antiepileptic drugs in the treatment of seizure.

Effect of perinatal asphyxia and carbamazepine treatment on cortical dopamine and DOPAC levels

Background

One of the most important manifestations of perinatal asphyxia is the occurrence of seizures, which are treated with antiepileptic drugs, such as carbamazepine. These early seizures, combined with pharmacological treatments, may influence the development of dopaminergic neurotransmission in the frontal cortex. This study aimed to determine the extracellular levels of dopamine and its main metabolite DOPAC in 30-day-old rats that had been asphyxiated for 45 min in a low (8%) oxygen chamber at a perinatal age and treated with daily doses of carbamazepine. Quantifications were performed using microdialysis coupled to a high-performance liquid chromatography (HPLC) system in basal conditions and following the use of the chemical stimulus.

Results

Significant decreases in basal and stimulated extracellular dopamine and DOPAC content were observed in the frontal cortex of the asphyxiated group, and these decreases were partially recovered in the animals administered daily doses of carbamazepine. Greater basal dopamine concentrations were also observed as an independent effect of carbamazepine.

Conclusions

Perinatal asphyxia plus carbamazepine affects extracellular levels of dopamine and DOPAC in the frontal cortex and stimulated the release of dopamine, which provides evidence for the altered availability of dopamine in cortical brain areas during brain development.

Clinical significance of interleukin-6, tumor necrosis factor-α and high-sensitivity C-reactive protein in neonates with hypoxic-ischemic encephalopathy

The present study aimed to investigate the potential roles of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and high-sensitivity C-reactive protein (Hs-CRP) in the progression and prognosis of neonatal hypoxic-ischemic encephalopathy (HIE). The observation group comprised 74 neonates with HIE and the control group comprised 74 healthy neonates. The serum levels of IL-6, TNF-α and Hs-CRP were measured in the patients with HIE and the normal control infants. The correlations between the variances in the levels of these inflammatory cytokines and the different clinical gradings and prognoses of the disease were analyzed. The data revealed significant upregulation of the serum levels of IL-6, TNF-α and Hs-CRP in patients with HIE. The increase in the levels of these inflammatory mediators correlated with the severity of the disease and also had a positive correlation with the prognosis of the disease. In conclusion, high levels of IL-6, TNF-α and Hs-CRP were observed in neonatal patients with HIE. Thus, these inflammatory mediators may play a role in the progression and prognosis of the disease.

Newly emerging therapies for neonatal seizures

The treatment of neonatal seizures has not changed significantly over the last 50 years despite advances in antiepileptic drug (AED) development for older children and adults. Recently new drugs have emerged some of which address age-specific challenges or mechanisms and will be discussed in this review. The loop diuretic bumetanide blocks the neuronal NKCC1 co-transporter and is thought specifically to supress seizures in the immature brain. Levetiracetam has been used in children and infants with good efficacy, an excellent safety profile, and near-ideal pharmacokinetic characteristics. Randomised controlled trials are now underway to test the efficacy of some newer AEDs for neonatal seizures. Topiramate has been shown to have neuroprotective properties in addition to its antiepileptic action and trials in babies with hypoxic-ischaemic encephalopathy are now planned. There is an urgent need to develop age-specific AEDs for preterm and term babies. These drugs must be evaluated with multicentre, collaborative trials using innovative methods and high ethical standards to overcome age-specific challenges with the ultimate aim of improving the outcome for neonates with seizures.

Findings and patterns on MRI and MR spectroscopy in neonates after therapeutic hypothermia for hypoxic ischemic encephalopathy treatment

OBJECTIVES

The purpose of this study is to describe the findings and patterns of injury on magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) after whole-body hypothermia treatment for neonatal hypoxic ischemic encephalopathy.

METHODS

A retrospective review of consecutive term neonates treated with whole-body hypothermia was performed. Data recorded included demographics and MRI and MRS findings, and day of life (DOL) studies were performed. Injury patterns were classified on MRI as deep, cortical, mixed, or diffuse. The relative apparent diffusion coefficient (rADC) was plotted against DOL scanned and the presence of lactate was recorded.

RESULTS

MRI was performed in 44 infants, 34 of whom also underwent MRS. MRI was abnormal in 32% of neonates, 29.5% of whom were imaged at DOL 4 to 8. rADC values were lowest in neonates scanned on DOL 4 and 5 and remained low up to DOL 8. The deep brain nuclei were involved in hypoxic ischemic encephalopathy in 93% of neonates with abnormal MRIs and lactate was identified on MRS in 18% of neonates between DOL 4 and 8.

CONCLUSIONS

MRI performed after therapeutic cooling was abnormal in 29.5% of neonates scanned on DOL 4 to 8. Deep nuclear injury was identified in 93% of neonates. Lactate was present on MRS in 18% of neonates, and rADC values were most reduced on MRI between DOL 4 and 8.

Moderate and severe perinatal asphyxia induces differential effects on cocaine sensitization in adult rats

Perinatal asphyxia (PA) increases the likelihood of suffering from dopamine-related disorders, such as ADHD and schizophrenia. Since dopaminergic transmission plays a major role in cocaine sensitization, the purpose of this study was to determine whether PA could be associated with altered behavioral sensitization to cocaine. To this end, adult rats born vaginally (CTL), by caesarean section (C+), or by C+ with 15 min (PA15, moderate PA) or 19 min (PA19, severe PA) of global anoxia were repeatedly administered with cocaine (i.p., 15 mg/kg) and then challenged with cocaine (i.p., 15 mg/kg) after a 5-day withdrawal period. In addition, c-Fos, FosB/ΔFosB, DAT, and TH expression were assessed in dorsal (CPu) and ventral (NAcc) striatum. Results indicated that PA15 rats exhibited an increased locomotor sensitization to cocaine, while PA19 rats displayed an abnormal acquisition of locomotor sensitization and did not express a sensitized response to cocaine. c-Fos expression in NAcc, but not in CPu, was associated with these alterations in cocaine sensitization. FosB/ΔFosB expression was increased in all groups and regions after repeated cocaine administration, although it reached lower expression levels in PA19 rats. In CTL, C+, and PA15, but not in PA19 rats, the expression of TH in NAcc was reduced in groups repeatedly treated with cocaine, independently of the challenge test. Furthermore, this reduction was more pronounced in PA15 rats. DAT expression remained unaltered in all groups and regions studied. These results suggest that moderate PA may increase the vulnerability to drug abuse and in particular to cocaine addiction.