Mild hypothermia and the distribution of cerebral lesions in neonates with hypoxic-ischemic encephalopathy

Volumetric changes in brain MRI of infants with hypoxic-ischemic encephalopathy and abnormal neurodevelopment who underwent therapeutic hypothermia

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is a severe neonatal complication that can result in 40-60 % of long-term morbidity. Magnetic Resonance Imaging (MRI) is a noninvasive method which is usually performed before discharge to visually assess acquired cerebral lesions associated with HIE and severity of lesions possibly providing a guide for detecting adverse outcomes. This study aims to evaluate the impact of HIE on brain volume changes observed in MRI scans performed at a mean 10 days of life, which can serve as a prognostic indicator for abnormal neurodevelopmental (ND) outcomes at 18-24 months among HIE infants.

METHODS

We retrospectively identified a cohort of HIE patients between June 2013 and March 2017. The inclusion criteria for therapeutic hypothermia (TH) were a gestational age ≥35 weeks, a birth weight ≥1800 g, and the presence of ≥ moderate HIE. Brain MRI was performed at a mean 10 days of life and brain volumes (total brain volume, cerebral volume, cerebellar volume, brain stem volume, and ventricle volume) were measured for quantitative assessment. At 18-24 months, the infants returned for follow-up evaluations, during which their cognitive, language, and motor skills were assessed using the Bayley Scales of Infant and Toddler Development III.

RESULTS

The study recruited a total of 240 infants between 2013 and 2017 for volumetric brain MRI evaluation. Among these, 83 were normal control infants, 107 were TH-treated HIE infants and 37 were HIE infants who did not receive TH due to contraindications. Clinical evaluation was further proceeded. We compared the brain volumes between the normal control infants (n = 83) with normal ND but TH-treated HIE infants (n = 76), abnormal ND TH-treated HIE infants (n = 31), and the severe HIE MRI group with no TH (n = 37). The abnormal ND TH-treated HIE infants demonstrated a significant decrease in brainstem volume and an increase in ventricle size (p < 0.001) (Table 4). Lastly, the severe brain MRI group who did not receive TH showed significantly smaller brain stem (p = 0.006), cerebellar (p = 0.006) and cerebrum volumes (p = 0.027), accompanied by larger ventricular size (p = 0.013) compared to the normal control group (Table 5).

CONCLUSION

In addition to assessing the location of brain injuries in MRI scans, the reduction in brain stem volume coupled with an increase in ventricular volume in HIE infants may serve as a biomarker indicating severe HIE and adverse long-term ND outcomes among HIE infants who either received therapeutic hypothermia (TH) treatment or not.

Distinct manifestations and potential mechanisms of seizures due to cortical versus white matter injury in children

PURPOSE

To study seizure manifestations and outcomes in children with cortical versus white matter injury, differences potentially explaining variability of epilepsy in children with cerebral palsy.

METHODS

In this population-based retrospective cohort study, MRIs of children with cerebral palsy due to ischemia or haemorrhage were classified according to presence or absence of cortical injury. MRI findings were then correlated with history of neonatal seizures, seizures during childhood, epilepsy syndromes, and seizure outcomes.

RESULTS

Of 256 children studied, neonatal seizures occurred in 57 and seizures during childhood occurred in 93. Children with neonatal seizures were more likely to develop seizures during childhood, mostly those with cortical injury. Cortical injury was more strongly associated with (1) developing seizures during childhood, (2) more severe epilepsy syndromes (infantile spasms syndrome, focal epilepsy, Lennox-Gastaut syndrome), and (3) less likelihood of reaching > 2 years without seizures at last follow-up, compared to children without cortical injury. Children without cortical injury, mainly those with white matter injury, were less likely to develop neonatal seizures and seizures during childhood, and when they did, epilepsy syndromes were more commonly febrile seizures and self-limited focal epilepsies of childhood, with most achieving > 2 years without seizures at last follow-up. The presence of cortical injury also influenced seizure occurrence, severity, and outcome within the different predominant injury patterns of the MRI Classification System in cerebral palsy, most notably white matter injury.

CONCLUSIONS

Epileptogenesis is understood with cortical injury but not well with white matter injury, the latter potentially related to altered postnatal white matter development or myelination leading to apoptosis, abnormal synaptogenesis or altered thalamic connectivity of cortical neurons. These findings, and the potential mechanisms discussed, likely explain the variability of epilepsy in children with cerebral palsy and epilepsy following early-life brain injury in general.

Hypothermic Protection in Neocortex Is Topographic and Laminar, Seizure Unmitigating, and Partially Rescues Neurons Depleted of RNA Splicing Protein Rbfox3/NeuN in Neonatal Hypoxic-Ischemic Male Piglets

The effects of hypothermia on neonatal encephalopathy may vary topographically and cytopathologically in the neocortex with manifestations potentially influenced by seizures that alter the severity, distribution, and type of neuropathology. We developed a neonatal piglet survival model of hypoxic-ischemic (HI) encephalopathy and hypothermia (HT) with continuous electroencephalography (cEEG) for seizures. Neonatal male piglets received HI-normothermia (NT), HI-HT, sham-NT, or sham-HT treatments. Randomized unmedicated sham and HI piglets underwent cEEG during recovery. Survival was 2-7 days. Normal and pathological neurons were counted in different neocortical areas, identified by cytoarchitecture and connectomics, using hematoxylin and eosin staining and immunohistochemistry for RNA-binding FOX-1 homolog 3 (Rbfox3/NeuN). Seizure burden was determined. HI-NT piglets had a reduced normal/total neuron ratio and increased ischemic-necrotic/total neuron ratio relative to sham-NT and sham-HT piglets with differing severities in the anterior and posterior motor, somatosensory, and frontal cortices. Neocortical neuropathology was attenuated by HT. HT protection was prominent in layer III of the inferior parietal cortex. Rbfox3 immunoreactivity distinguished cortical neurons as: Rbfox3-positive/normal, Rbfox3-positive/ischemic-necrotic, and Rbfox3-depleted. HI piglets had an increased Rbfox3-depleted/total neuron ratio in layers II and III compared to sham-NT piglets. Neuronal Rbfox3 depletion was partly rescued by HT. Seizure burdens in HI-NT and HI-HT piglets were similar. We conclude that the neonatal HI piglet neocortex has: (1) suprasylvian vulnerability to HI and seizures; (2) a limited neuronal cytopathological repertoire in functionally different regions that engages protective mechanisms with HT; (3) higher seizure burden, insensitive to HT, that is correlated with more panlaminar ischemic-necrotic neurons in the somatosensory cortex; and (4) pathological RNA splicing protein nuclear depletion that is sensitive to HT. This work demonstrates that HT protection of the neocortex in neonatal HI is topographic and laminar, seizure unmitigating, and restores neuronal depletion of RNA splicing factor.

Is Selective Head Cooling Combined with Whole-Body Cooling the Most Effective Hypothermia Method for Neonatal Hypoxic-Ischemic Encephalopathy?

This study aimed to compare combined hypothermia (CH) to the 2 classical therapeutic hypothermia (TH) methods selective head cooling (SHC) and whole-body cooling (WBC). This retrospective cohort study included neonates who underwent CH, SHC, and WBC between 2012 and 2020. Mean rectal temperature was maintained at 33.5 ± 0.5°C by cooling the head and the body in the CH group, at 34.5 ± 0.5°C by cooling the head in the SHC group, and at 33.5 ± 0.5°C by cooling the body in the WBC group. The groups were compared in terms of side effects, magnetic resonance imaging (MRI) scores, and status at discharge. The study included 60 neonates in the CH group, 112 in the WBC group, and 27 in the SHC group. There was no significant difference in side effects between the groups (p > 0.05). There was no significant difference in brain MRI scores between the groups (p > 0.05); however, gray matter, white matter, and total MRI scores in the CH group were lower than in the WBC group. Duration of hospitalization was shorter in the CH group than in the other two groups (p = 0.022). CH was not associated with more side effects than the two classical TH methods. In addition, some of these findings suggest that CH might result in better clinical outcome than the two classical TH methods.

Administration of selective brain hypothermia using a simple cooling device in neonatal rats

BACKGROUND

The interruption of oxygen and blood supply to the newborn brain around the time of birth is a risk factor for hypoxic-ischemic encephalopathy and may lead to infant mortality or lifelong neurological impairments. Currently, therapeutic hypothermia, the cooling of the infant's head or entire body, is the only treatment to curb the extent of brain damage.

NEW METHOD

In this study, we designed a focal brain cooling device that circulates cooled water at a steady state temperature of 19 ± 1 °C through a coil of tubing fitted onto the neonatal rat's head. We tested its ability to selectively decrease brain temperature and offer neuroprotection in a neonatal rat model of hypoxic-ischemic brain injury.

RESULTS

Our method cooled the brain to 30-33 °C in conscious pups, while keeping the core body temperature approximately 3.2 °C warmer. Furthermore, the application of the cooling device to the neonatal rat model demonstrated a reduction in brain volume loss compared to pups maintained at normothermia and achieved a level of brain tissue protection the same as that of whole-body cooling.

COMPARISON WITH EXISTING METHODS

Prevailing methods of selective brain hypothermia are designed for adult animal models rather than for immature animals such as the rat as a conventional model of developmental brain pathology. Contrary to existing methods, our method of cooling does not require surgical manipulation or anaesthesia.

CONCLUSION

Our simple, economical, and effective method of selective brain cooling is a useful tool for rodent studies in neonatal brain injury and adaptive therapeutic interventions.

Neuroprotective effect of selective hypothermic cerebral perfusion in extracorporeal cardiopulmonary resuscitation: A preclinical study

Objective

Neurologic complications seriously affect the survival rate and quality of life in patients with extracorporeal cardiopulmonary resuscitation (ECPR) undergoing cardiac arrest. This study aimed to repurpose selective hypothermic cerebral perfusion (SHCP) as a novel approach to protect the brains of these patients.

Methods

Rats were randomly allocated to Sham, ECPR, and SHCP combined ECPR (CP-ECPR) groups. In the ECPR group, circulatory resuscitation was performed at 6 minutes after asphyxial cardiac arrest by extracorporeal membrane oxygenation. The vital signs were monitored for 3 hours, and body and brain temperatures were maintained at the normal level. In the CP-ECPR group, the right carotid artery catheterization serving as cerebral perfusion was connected with the extracorporeal membrane oxygenation device to achieve selective brain cooling (26-28 °C). Serum markers of brain injury and pathomorphologic changes in the hippocampus were evaluated. Three biological replicates further received RNA sequencing in ECPR and CP-ECPR groups. Microglia activation and inflammatory cytokines in brain tissues and serum were detected.

Results

SHCP rapidly reduced the brain-targeted temperature and significantly alleviated nerve injury. This was evident from the reduced brain injury serum biomarker levels, lower pathologic scores, and more surviving neurons in the hippocampus in the CP-ECPR group. Furthermore, more differentially expressed genes for inflammatory responses were clustered functionally according to Kyoto Encyclopedia of Genes and Genomes pathway analysis. And SHCP reduced microglia activation and the release of proinflammatory mediators.

Conclusions

Our preliminary data indicate that SHCP may serve as a potential therapy to attenuate brain injury via downregulation of neuroinflammation in patients with ECPR.

Outcome of non-cooled asphyxiated infants with under-recognised or delayed-onset encephalopathy

OBJECTIVE

To describe the clinical characteristics, MRI findings and neurodevelopmental outcome of infants with documented perinatal asphyxia and seizure onset within 24 hours after birth who were not selected for therapeutic hypothermia (TH).

DESIGN

Retrospective cohort study.

SETTING AND PATIENTS

(Near-)term infants with documented perinatal asphyxia referred to two Dutch level III neonatal units with neonatal encephalopathy (NE) and seizures <24 hours after birth not treated with TH. Infants with a diagnosis other than NE following perinatal asphyxia causing the seizures were excluded.

MAIN OUTCOME MEASURES

Clinical characteristics, findings on cranial MRI performed within 8 days after birth and neurodevelopmental outcome assessed using the Griffiths Mental Development Scales at 18 months or Bayley Scales of Infant and Toddler Development-Third Edition at 2 years of age.

RESULTS

39 infants were included. All had abnormalities on MRI. Predominant white matter/watershed injury was the most common pattern of injury, 23 (59%). 7 (18%) infants had predominant basal ganglia/thalamus injury, 3 (8%) near total brain injury, 5 (13%) arterial ischaemic stroke, 1 (3%) an intraventricular haemorrhage. Adverse outcome was seen in 51%: 6 died, 11 developed cerebral palsy (spastic n=8, dyskinetic n=3), 2 had neurodevelopmental delay, 1 had severe hearing impairment.

CONCLUSIONS

All infants with documented perinatal asphyxia and seizure onset within 24 hours after birth who did not receive TH had abnormalities on MRI. 51% had an adverse outcome. Better methods for recognition of infants who might benefit from TH and careful neurodevelopmental follow-up are urgently needed.

Persistent cortical and white matter inflammation after therapeutic hypothermia for ischemia in near-term fetal sheep

Background

Therapeutic hypothermia significantly improves outcomes after moderate–severe hypoxic-ischemic encephalopathy (HIE), but it is partially effective. Although hypothermia is consistently associated with reduced microgliosis, it is still unclear whether it normalizes microglial morphology and phenotype.

Methods

Near-term fetal sheep (n = 24) were randomized to sham control, ischemia-normothermia, or ischemia-hypothermia. Brain sections were immunohistochemically labeled to assess neurons, microglia and their interactions with neurons, astrocytes, myelination, and gitter cells (microglia with cytoplasmic lipid granules) 7 days after cerebral ischemia. Lesions were defined as areas with complete loss of cells. RNAscope^® was used to assess microglial phenotype markers CD86 and CD206.

Results

Ischemia-normothermia was associated with severe loss of neurons and myelin (p < 0.05), with extensive lesions, astrogliosis and microgliosis with a high proportion of gitter cells (p < 0.05). Microglial wrapping of neurons was present in both the ischemia groups. Hypothermia improved neuronal survival, suppressed lesions, gitter cells and gliosis (p < 0.05), and attenuated the reduction of myelin area fraction. The “M1” marker CD86 and “M2” marker CD206 were upregulated after ischemia. Hypothermia partially suppressed CD86 in the cortex only (p < 0.05), but did not affect CD206.

Conclusions

Hypothermia prevented lesions after cerebral ischemia, but only partially suppressed microglial wrapping and M1 marker expression. These data support the hypothesis that persistent upregulation of injurious microglial activity may contribute to partial neuroprotection after hypothermia, and that immunomodulation after rewarming may be an important therapeutic target.

Neuroprotective Effect of Eco-Sustainably Extracted Grape Polyphenols in Neonatal Hypoxia-Ischemia

Polyphenols are natural compounds with promising prophylactic and therapeutic applications. However, their methods of extraction, using organic solvents, may prove to be unsuitable for daily consumption or for certain medical indications. Here, we describe the neuroprotective effects of grape polyphenols extracted in an eco-sustainable manner in a rat model of neonatal hypoxia-ischemia (NHI). Polyphenols (resveratrol, pterostilben and viniferin) were obtained using a subcritical water extraction technology to avoid organic solvents and heavy metals associated with chemical synthesis processes. A resveratrol or a polyphenol cocktail were administered to pregnant females at a nutritional dose and different time windows, prior to induction of NHI in pups. Reduced brain edema and lesion volumes were observed in rat pups whose mothers were supplemented with polyphenols. Moreover, the preservation of motor and cognitive functions (including learning and memory) was evidenced in the same animals. Our results pave the way to the use of polyphenols to prevent brain lesions and their associated deficits that follow NHI, which is a major cause of neonatal death and disabilities.

Free Radicals and Neonatal Brain Injury: From Underlying Pathophysiology to Antioxidant Treatment Perspectives

Free radicals play a role of paramount importance in the development of neonatal brain injury. Depending on the pathophysiological mechanisms underlying free radical overproduction and upon specific neonatal characteristics, such as the GA-dependent maturation of antioxidant defenses and of cerebrovascular autoregulation, different profiles of injury have been identified. The growing evidence on the detrimental effects of free radicals on the brain tissue has led to discover not only potential biomarkers for oxidative damage, but also possible neuroprotective therapeutic approaches targeting oxidative stress. While a more extensive validation of free radical biomarkers is required before considering their use in routine neonatal practice, two important treatments endowed with antioxidant properties, such as therapeutic hypothermia and magnesium sulfate, have become part of the standard of care to reduce the risk of neonatal brain injury, and other promising therapeutic strategies are being tested in clinical trials. The implementation of currently available evidence is crucial to optimize neonatal neuroprotection and to develop individualized diagnostic and therapeutic approaches addressing oxidative brain injury, with the final aim of improving the neurological outcome of this population.

Early Magnetic Resonance Imaging Predicts 30-Month Outcomes after Therapeutic Hypothermia for Neonatal Encephalopathy

OBJECTIVE

To evaluate the association of therapeutic hypothermia with magnetic resonance imaging (MRI) findings and 30-month neurodevelopment in term neonatal encephalopathy.

STUDY DESIGN

Cross-sectional analysis of 30-month neurodevelopment (IQR 19.0-31.4) in a prospective cohort of mild-to-severe neonatal encephalopathy imaged on day 4 (1993-2017 with institutional implementation of therapeutic hypothermia in 2007). MRI injury was classified as normal, watershed, or basal ganglia/thalamus. Abnormal motor outcome was defined as Bayley-II psychomotor developmental index <70, Bayley-III motor score <85 or functional motor deficit. Abnormal cognitive outcome was defined as Bayley-II mental developmental index <70 or Bayley-III cognitive score <85. Abnormal composite outcome was defined as abnormal motor and/or cognitive outcome, or death. The association of therapeutic hypothermia with MRI and outcomes was evaluated with multivariable logistic regression adjusted for propensity to receive therapeutic hypothermia.

RESULTS

Follow-up was available in 317 (78%) surviving children, of whom 155 (49%) received therapeutic hypothermia. Adjusting for propensity, therapeutic hypothermia was independently associated with decreased odds of abnormal motor (OR 0.15, 95% CI 0.06-0.40, P < .001) and cognitive (OR 0.11, 95% CI 0.04-0.33, P < .001) outcomes. This association remained statistically significant after adjustment for injury pattern. The predictive accuracy of MRI pattern for abnormal composite outcome was unchanged between therapeutic hypothermia-treated (area under the receiver operating curve 0.76; 95% CI 0.61-0.91) and untreated (area under the receiver operating curve 0.74; 95% CI 0.67-0.81) infants. The negative predictive value of normal MRI was high in therapeutic hypothermia-treated and untreated infants (motor 96% vs 90%; cognitive 99% vs 95%).

CONCLUSIONS

Therapeutic hypothermia is associated with lower rates of brain injury and adverse 30-month outcomes after neonatal encephalopathy. The predictive accuracy of MRI in the first week of life is unchanged by therapeutic hypothermia. Normal MRI remains reassuring for normal 30-month outcome after therapeutic hypothermia.

Oleuropein Activates Neonatal Neocortical Proteasomes, but Proteasome Gene Targeting by AAV9 Is Variable in a Clinically Relevant Piglet Model of Brain Hypoxia-Ischemia and Hypothermia

Cerebral hypoxia-ischemia (HI) compromises the proteasome in a clinically relevant neonatal piglet model. Protecting and activating proteasomes could be an adjunct therapy to hypothermia. We investigated whether chymotrypsin-like proteasome activity differs regionally and developmentally in the neonatal brain. We also tested whether neonatal brain proteasomes can be modulated by oleuropein, an experimental pleiotropic neuroprotective drug, or by targeting a proteasome subunit gene using recombinant adeno-associated virus-9 (AAV). During post-HI hypothermia, we treated piglets with oleuropein, used AAV-short hairpin RNA (shRNA) to knock down proteasome activator 28γ (PA28γ), or enforced PA28γ using AAV-PA28γ with green fluorescent protein (GFP). Neonatal neocortex and subcortical white matter had greater proteasome activity than did liver and kidney. Neonatal white matter had higher proteasome activity than did juvenile white matter. Lower arterial pH 1 h after HI correlated with greater subsequent cortical proteasome activity. With increasing brain homogenate protein input into the assay, the initial proteasome activity increased only among shams, whereas HI increased total kinetic proteasome activity. OLE increased the initial neocortical proteasome activity after hypothermia. AAV drove GFP expression, and white matter PA28γ levels correlated with proteasome activity and subunit levels. However, AAV proteasome modulation varied. Thus, neonatal neocortical proteasomes can be pharmacologically activated. HI slows the initial proteasome performance, but then augments ongoing catalytic activity. AAV-mediated genetic manipulation in the piglet brain holds promise, though proteasome gene targeting requires further development.

Venovenous versus venoarterial extracorporeal membrane oxygenation among infants with hypoxic-ischemic encephalopathy: is there a difference in outcome?

OBJECTIVE

Our hypothesis was that among infants with hypoxic-ischemic encephalopathy (HIE), venoarterial (VA), compared to venovenous (VV), extracorporeal membrane oxygenation (ECMO) is associated with an increased risk of mortality or intracranial hemorrhage (ICH).

DESIGN/METHODS

Retrospective cohort analysis of infants in the Children's Hospitals Neonatal Database from 2010 to 2016 with moderate or severe HIE, gestational age ≥36 weeks, and ECMO initiation <7 days of age. The primary outcome was mortality or ICH.

RESULTS

Severe HIE was more common in the VA ECMO group (n = 57), compared to the VV ECMO group (n = 53) (47.4% vs. 26.4%, P = 0.02). VA ECMO was associated with a significantly higher risk of death or ICH [57.9% vs. 34.0%, aOR 2.39 (1.08-5.28)] and mortality [31.6% vs. 11.3%, aOR 3.06 (1.08-8.68)], after adjusting for HIE severity.

CONCLUSIONS

In HIE, VA ECMO was associated with a higher incidence of mortality or ICH. VV ECMO may be beneficial in this population.

Combining Hypothermia and Oleuropein Subacutely Protects Subcortical White Matter in a Swine Model of Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxia-ischemia (HI) causes white matter injury that is not fully prevented by therapeutic hypothermia. Adjuvant treatments are needed. We compared myelination in different piglet white matter regions. We then tested whether oleuropein (OLE) improves neuroprotection in 2- to 4-day-old piglets randomized to undergo HI or sham procedure and OLE or vehicle administration beginning at 15 minutes. All groups received overnight hypothermia and rewarming. Injury in the subcortical white matter, corpus callosum, internal capsule, putamen, and motor cortex gray matter was assessed 1 day later. At baseline, piglets had greater subcortical myelination than in corpus callosum. Hypothermic HI piglets had scant injury in putamen and cerebral cortex. However, hypothermia alone did not prevent the loss of subcortical myelinating oligodendrocytes or the reduction in subcortical myelin density after HI. Combining OLE with hypothermia improved post-HI subcortical white matter protection by preserving myelinating oligodendrocytes, myelin density, and oligodendrocyte markers. Corpus callosum and internal capsule showed little HI injury after hypothermia, and OLE accordingly had minimal effect. OLE did not affect putamen or motor cortex neuron counts. Thus, OLE combined with hypothermia protected subcortical white matter after HI. As an adjuvant to hypothermia, OLE may subacutely improve regional white matter protection after HI.

Neuroprotection by Therapeutic Hypothermia

Hypothermia therapy is an old and important method of neuroprotection. Until now, many neurological diseases such as stroke, traumatic brain injury, intracranial pressure elevation, subarachnoid hemorrhage, spinal cord injury, hepatic encephalopathy, and neonatal peripartum encephalopathy have proven to be suppressed by therapeutic hypothermia. Beneficial effects of therapeutic hypothermia have also been discovered, and progress has been made toward improving the benefits of therapeutic hypothermia further through combination with other neuroprotective treatments and by probing the mechanism of hypothermia neuroprotection. In this review, we compare different hypothermia induction methods and provide a summarized account of the synergistic effect of hypothermia therapy with other neuroprotective treatments, along with an overview of hypothermia neuroprotection mechanisms and cold/hypothermia-induced proteins.

Functional Connectivity in Term Neonates With Hypoxic-Ischemic Encephalopathy Undergoing Therapeutic Hypothermia

BACKGROUND

We investigated whether therapeutic hypothermia and rewarming impact functional connectivity using electroencephalography (EEG) as a measure in neonates with hypoxic-ischemic encephalopathy. We hypothesized that EEG coherence and voltage correlations would be lower and phase lag greater in infants with hypoxic-ischemic encephalopathy than control subjects and that functional connectivity would evolve during therapeutic hypothermia with the greatest improvement occurring during rewarming.

METHODS

This study was a retrospective study of 14 term neonates (greater than 37 weeks) with moderate hypoxic-ischemic encephalopathy who underwent therapeutic hypothermia and rewarming. Continuous EEG and video monitoring was conducted for 96 hours during therapeutic hypothermia and rewarming. The primary quantitative EEG measures of functional connectivity were coherence, phase lag, and voltage correlations. These EEG parameters were compared with a cohort of normal age-matched neonates.

RESULTS

Neonates with hypoxic-ischemic encephalopathy had marked decreases in power, coherences, and voltage correlation and increases in phase lag when compared with control neonates. However, there were no significant changes in these measures between therapeutic hypothermia and rewarming.

CONCLUSIONS

Neonates with hypoxic-ischemic encephalopathy demonstrate significant abnormalities in functional connectivity compared with control subjects. These abnormalities persist through therapeutic hypothermia and rewarming and are not altered after rewarming. Although hypoxic-ischemic encephalopathy is associated with impaired functional brain connectivity, there is no evidence, using quantitative EEG measures, that therapeutic hypothermia or rewarming either improves or exacerbates these abnormalities in connectivity.

Therapeutic Hypothermia in Neonatal Hypoxic-Ischemic Encephalopathy

PURPOSE OF REVIEW

Therapeutic hypothermia reduces death or disability in term and near-term infants with moderate-severe hypoxic-ischemic encephalopathy. Nevertheless, many infants still survive with disability, despite hypothermia, supporting further research in to ways to further improve neurologic outcomes.

RECENT FINDINGS

Recent clinical and experimental studies have refined our understanding of the key parameters for hypothermic neuroprotection, including timing of initiation, depth, and duration of hypothermia, and subsequent rewarming rate. However, important knowledge gaps remain. There is encouraging clinical evidence from a small phase II trial that combined treatment of hypothermia with recombinant erythropoietin further reduces risk of disability but definitive studies are still needed. In conclusion, recent studies suggest that current protocols for therapeutic hypothermia are near-optimal, and that the key to better neurodevelopmental outcomes is earlier diagnosis and initiation of hypothermia after birth. Further research is essential to find and evaluate ways to further improve outcomes after hypoxic-ischemic encephalopathy, including add-on therapies for therapeutic hypothermia and preventing pyrexia during labor and delivery.

Fetal and neonatal neuroimaging

Magnetic resonance imaging (MRI) can provide detail of the soft tissues of the fetal and neonatal brain that cannot be obtained by any other imaging modality. Conventional T1 and T2 weighted sequences provide anatomic detail of the normally developing brain and can demonstrate lesions, including those associated with preterm birth, hypoxic ischemic encephalopathy, perinatal arterial stroke, infections, and congenital malformations. Specialized imaging techniques can be used to assess cerebral vasculature (magnetic resonance angiography and venography), cerebral metabolism (magnetic resonance spectroscopy), cerebral perfusion (arterial spin labeling), and function (functional MRI). A wealth of quantitative tools, most of which were originally developed for the adult brain, can be applied to study the developing brain in utero and postnatally including measures of tissue microstructure obtained from diffusion MRI, morphometric studies to measure whole brain and regional tissue volumes, and automated approaches to study cortical folding. In this chapter, we aim to describe different imaging approaches for the fetal and neonatal brain, and to discuss their use in a range of clinical applications.

Perinatal hypoxic-ischemic brain injury in large animal models: Relevance to human neonatal encephalopathy

Perinatal hypoxia-ischemia resulting in death or lifelong disabilities remains a major clinical disorder. Neonatal models of hypoxia-ischemia in rodents have enhanced our understanding of cellular mechanisms of neural injury in developing brain, but have limitations in simulating the range, accuracy, and physiology of clinical hypoxia-ischemia and the relevant systems neuropathology that contribute to the human brain injury pattern. Large animal models of perinatal hypoxia-ischemia, such as partial or complete asphyxia at the time of delivery of fetal monkeys, umbilical cord occlusion and cerebral hypoperfusion at different stages of gestation in fetal sheep, and severe hypoxia and hypoperfusion in newborn piglets, have largely overcome these limitations. In monkey, complete asphyxia produces preferential injury to cerebellum and primary sensory nuclei in brainstem and thalamus, whereas partial asphyxia produces preferential injury to somatosensory and motor cortex, basal ganglia, and thalamus. Mid-gestational fetal sheep provide a valuable model for studying vulnerability of progenitor oligodendrocytes. Hypoxia followed by asphyxia in newborn piglets replicates the systems injury seen in term newborns. Efficacy of post-insult hypothermia in animal models led to the success of clinical trials in term human neonates. Large animal models are now being used to explore adjunct therapy to augment hypothermic neuroprotection.

Protein S100B in umbilical cord blood as a potential biomarker of hypoxic-ischemic encephalopathy in asphyxiated newborns

BACKGROUND

Neonatal hypoxic ischemic encephalopathy (HIE) is a devastating condition resulting from a sustained lack of oxygen during birth. The interest in identifying a relevant biomarker of HIE has thrown into limelight the role of protein S100B as a clinical diagnostic marker of hypoxic brain damage in neonates.

AIMS

To evaluate the diagnostic value of protein S100B, measured in umbilical cord blood immediately after birth, as a useful biomarker in the diagnosis of HIE Sarnat stages II-III as well as a marker for long-term mortality and morbidity.

STUDY DESIGN

Protein S100B was analyzed in cord blood sampled at birth from 13 newborns later diagnosed with stage II-III HIE and compared with 21 healthy controls. S100B concentrations were related to cord artery pH, amplitude-integrated electroencephalography (aEEG), stage of HIE, and death/sequelae up to an age of 6years. Both parametric and non-parametric statistics were used with a two-sided P<0.05 considered significant.

RESULTS

The difference in S100B concentration was marginally statistically significant between HIE cases and controls (P=0.056). Cord blood acidosis (P=0.046), aEEG pattern severity (P=0.030), HIE severity (P=0.027), and condition at 6-year follow-up (healthy/permanent sequelae/death; P=0.027) were all related to an increase in S100B concentration.

CONCLUSIONS

Protein S100B in neonates suffering from HIE stages II-III appeared elevated in umbilical cord blood at birth. The S100B concentrations were positively associated to the severity of disease and the risk of suffering from neurodevelopmental sequelae and even death.

Neonatal neurological examination during the first 6h after birth

BACKGROUND

Few neurological assessments are easily performed during the first 6h after birth.

AIMS

To assess a cohort of low risk term born newborns within the first 6h and at 48h after birth using the Hammersmith Neonatal Neurological Examination.

STUDY DESIGN AND SUBJECTS

A population of low risk term born newborns was examined within 3h from birth or between 3 and 6h. Each infant was re-assessed at 48h, establishing the range and frequency distribution of neonatal neurological scores at each time point.

RESULTS

Of the 124 full-term born newborns, 62 were assessed at 0-3h and 62 at 3-6h. All infants were re-assessed at 48h. For 23/34 of the neurological items, the range and median scores were similar across the 3 time points. In the remaining 11 items the three groups had a similar range of scores but the median scores were different with different rates of changes. In 6 of the 11 the median scores at 3-6h were similar to those observed at 48h but they appeared to be 'less mature' at 0-3h. Only in one item the median scores were consistently different at the 3 time points.

CONCLUSIONS

Our results suggest that a neurological examination can already be reliably performed soon after birth. These findings will help in the interpretation of the few items that show changes with increasing postnatal age.

Clinical characteristics predicting abnormal brain magnetic resonance image findings in hypoxic-ischemic encephalopathy infants

BACKGROUND

The aim of this study was to elucidate the specific clinical characteristics associated with abnormal brain magnetic resonance image (MRI) findings in hypoxic ischemic encephalopathy (HIE) infants in order to discern how to predict poorer outcomes more accurately.

METHODS

A retrospective data analysis of HIE infants admitted to the neonatal intensive care unit of a tertiary hospital was performed. Baseline perinatal information and physical and neurological findings were compared in HIE infants according to the presence of abnormal brain MRI findings.

RESULTS

A total of 69 infants were enrolled in the study. Of these, 48(69.6%) infants received therapeutic hypothermia, and 60(87.0%) infants presented abnormal findings on brain MRI. Decreased muscle tone and lower Apgar scores were more often observed in infants with abnormal MRI results(P<0.05). The presence of hypotonia and 1- and 5-minute Apgar scores equal to or less than the yielded cut-off values (5.5 and 7.5, respectively)were associated with a 7.23-, 9.14-, 9.78-fold increased risk of having abnormal brain MRI results.

CONCLUSIONS

As muscle tone and Apgar scores were associated with abnormal brain MRI findings in HIE infants, these clinical characteristics may serve as early indicators of poor neurodevelopmental outcomes and signal the need for special attention and in-depth follow-up by MRI.

Basal ganglia perfusion using dynamic color Doppler sonography in infants with hypoxic ischemic encephalopathy receiving therapeutic hypothermia: a pilot study

BACKGROUND

The objective of this study was to evaluate the cerebral perfusion of the basal ganglia in infants with hypoxic-ischemic encephalopathy (HIE) receiving hypothermia using dynamic color Doppler sonography (CDS) and investigate for any correlation between these measurements and survival.

METHODS

Head ultrasound (HUS) was performed with a 9S4 MHz sector transducer in HIE infants submitted to hypothermia as part of their routine care. Measurements of cerebral perfusion intensity (CPI) with an 11LW4 MHz linear array transducer were performed to obtain static images and DICOM color Doppler videos of the blood flow in the basal ganglia area. Clinical and radiological data were evaluated retrospectively. The video images were analyzed by two radiologists using dedicated software, which allows automatic quantification of color Doppler data from a region of interest (ROI) by dynamically assessing color pixels and flow velocity during the heart cycle. CPI is expressed in cm/sec and is calculated by multiplying the mean velocity of all pixels divided by the area of the ROI. Three videos of 3 seconds each were obtained of the ROI, in the coronal plane, and used to calculate the CPI. Data are presented as mean ± SEM or median (quartiles).

RESULTS

A total of 28 infants were included in this study: 16 male, 12 female. HUS was performed within the first 48 hours of therapeutic hypothermia treatment. CPI values were significantly higher in the seven non-survivors when compared to survivors (0.226±0.221 vs. 0.111±0.082 cm/sec; P=0.02).

CONCLUSIONS

Increased perfusion intensity of the basal ganglia area within the first 48 of therapeutic hypothermia treatment was associated with poor outcome in neonates with HIE.

Intraventricular hemorrhage in term neonates with hypoxic-ischemic encephalopathy: a comparison study between neonates treated with and without hypothermia

BACKGROUND

To retrospectively determine the prevalence of intraventricular hemorrhage (IVH) in term neonates with hypoxic-ischemic encephalopathy (HIE) using head ultrasound (HUS) and MRI, and to compare the incidence of IVH in term babies with HIE treated by therapeutic hypothermia versus those managed conventionally.

METHODS

A total of 61 term neonates from two institutions were diagnosed with HIE shortly after birth. Thirty infants from one institution were treated with whole body hypothermia. These infants had to satisfy the entry criteria for the neonatal hypothermia protocol of the institution. Thirty-one neonates underwent conventional treatment at the second institution. At that time, hypothermia was not yet a standard of care at that institution. All the neonates underwent HUS in their first 23 days of life. The 54 survivors also underwent MRI. The imaging studies were all reviewed for IVH.

RESULTS

Amongst the 30 babies, who received whole body hypothermia, there were 18 males and 12 females, the mean birth weight was 3.5 kg (2.5 to 5.2 kg), and the HUS study was performed within 14.8 to 41 hours of life. The group of 31 infants treated conventionally was comprised of 12 boys and 19 girls, the infants had an average birth weight of 3.3 kg (2.3 to 4.2 kg), and they underwent HUS 1 to 23 days after birth, with only five children being older than 1 week at the time of the imaging studies. Four of the 61 infants (7%) were diagnosed with IVH on HUS. Three were confirmed with MRI. The fourth case showed a bilateral enlarged choroid plexus on HUS, but IVH could not be confirmed with MRI, as the infant did not survive. In the group of neonates treated with hypothermia, there were three cases (10%) of IVH, whereas in the group managed conventionally, IVH occurred in one infant (3%).

CONCLUSIONS

Our study shows that IVH remains uncommon in term infants with HIE. IVH was more prevalent in the group treated with hypothermia.

Therapeutic hypothermia for infants with hypoxic ischemic encephalopathy: A five years' single center experience in Kuwait

OBJECTIVE

We aimed to evaluate the effect of therapeutic hypothermia (TH) on brain MRI findings, neurological outcome, and mortality in patients with perinatal hypoxic ischemic encephalopathy (HIE) and compare between two modalities of TH: whole body cooling (WBC) and selective head cooling (SHC).

PATIENTS AND METHODS

Sixty-two inborn babies with HIE admitted to the NICU of a Kuwaiti teaching hospital between 2006 and 2013 were retrospectively reviewed. Patients were divided into two groups: group 1 (2006-2008, n = 30) never received hypothermia, and group 2 (2009-2013, n = 32) treated with hypothermia. Group 2 patients were chronologically divided into two subgroups: 2a, the SHC, (2009-2010, n = 15) and 2b, the WBC, (2011-2013, n = 17). Brain MRI taken 7-10 days after birth, neurological status and mortality at time of hospital discharge were evaluated.

RESULTS

Patients who received TH showed significantly fewer MRI hypoxic changes (P = 0.04) and had better neurological outcome. Their need for anticonvulsants diminished (P = 0.04). However, their need for inotropes and duration of mechanical ventilation were increased (P = 0.001 & 0.02 respectively). No significant difference in mortality was found between the two groups (P = 0.6). In regression analysis, only MRI hypoxic changes predicted the occurrence of neurological abnormalities (P = 0.001). No difference in brain MRI findings, neurological outcome and mortality was observed between subgroups 2a and 2b (P > 0.05).

CONCLUSION

TH improved the neurological outcome of HIE patients but had no effect on mortality. There was no difference between the two modalities of TH on patients' outcome.

Characterizing longitudinal changes in rabbit brains infected with Angiostrongylus Cantonensis based on diffusion anisotropy

Angiostrongylus cantonensis has become a global source of infection in recent years, and the differential diagnosis and timely follow-up are crucial in the management of the infection. Magnetic resonance imaging (MRI) has been suggested as a non-invasive technique in characterizing and localizing lesions during the parasitic infections in the brain. Non-invasive diffusion tensor imaging (DTI) can be used to distinguish microscopic cerebral structures but cannot resolve the more complicated neural structure. Several methods have been proposed to overcome this limitation. One such method, generalized q-sampling imaging (GQI), can be applied to a variety of datasets, including the single shell, multi-shell or grid sampling schemes, which are believed to resolve complicated crossing fibers. This study aimed to characterize angiostrongyliasis in the rabbit brain over a 6-week period using anatomical and diffusion MRI, including DTI and GQI. Our anatomical T2WI and R2 mapping results showed that the ventricle size of the rabbit brain increased after A. cantonensis larvae infection, and the DTI and GQI indices both showed pathological changes in the corpus callosum, hippocampus and cortex over a 6-week infection period. These results were consistent with our histopathological findings. Our results demonstrated that the diagnosis of larvae infection using anatomical and diffusion MRI is possible and that follow-up characterization is informative in revealing the effects of angiostrongyliasis in various brain areas. These support the use of anatomical and diffusion MRI was helpful for diagnosis of eosinophilic meningitis caused by A. cantonensis infection. This non-invasive MRI platform could be used to improve the management of eosinophilic meningitis or eosinophilic meningoencephalitis in humans.

The bleeding newborn: A review of presentation, diagnosis, and management

The neonatal hemostatic system is continuously developing with rapidly changing concentrations of many coagulation proteins. Thus, determining the etiology of bleeding in a newborn has additional challenges beyond those seen in older children or adults. Bleeding can be seen in both well and sick newborns due to congenital causes, such as hemophilia or von Willebrand disease, and acquired causes, such as liver failure or disseminated intravascular coagulation. Traditional coagulation testing should be interpreted with caution and with the help of a hematologist, if possible, due to the greatly different normal ranges between neonates as compared with older children and adults. However, despite these challenges, both clinical and laboratory clues can guide physicians appropriately to diagnose and treat the bleeding newborn.

Comparison of selective head cooling versus whole-body cooling

BACKGROUND

This study compared selective head cooling (SHC) and whole-body cooling (WBC) in newborns with hypoxic-ischemic encephalopathy (HIE).

METHODS

We conducted a prospective randomized small-scale pilot study in newborns with HIE, born after >35 weeks of gestation. The patients were randomly assigned to receive SHC or WBC.

RESULTS

The SHC group consisted of 17 patients, and the WBC group, 12 patients. There was no significant difference in adverse effects related to cooling therapy between the two groups. During the 12 month study period, seven patients in the SHC group and four in the WBC group died, but the difference was not significant (P = 0.667). Among the patients alive at 12 months after treatment, six in the SHC group and four in the WBC group had severe disabilities; the difference was not significant (P = 0.671). When the composite outcome of death or severe disability was evaluated, the difference between the SHC group (77%, n = 13) and the WBC group (67%, n = 8) was not significant (P = 0.562). Moreover, the number of survivors without disability at 12 months after treatment did not differ significantly between the SHC group (n = 3) and the WBC group (n = 4; P = 0.614).

CONCLUSIONS

There were no significant differences in adverse effects, 12 month neuromotor development, or mortality rate between SHC and WBC in newborns with HIE, born after >35 weeks of gestation.

Therapeutic hypothermia and hypoxia-ischemia in the term-equivalent neonatal rat: characterization of a translational preclinical model

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is a major cause of morbidity in survivors. Therapeutic hypothermia (TH) is the only available intervention, but the protection is incomplete. Preclinical studies of HIE/TH in the rodent have relied on the postnatal day (P) 7 rat whose brain approximates a 32-36 wk gestation infant, less relevant for these studies. We propose that HIE and TH in the term-equivalent P10 rat will be more translational.

METHODS

P10-11 rat pups were subjected to unilateral hypoxia-ischemia (HI) and 4 h recovery in normothermic (N) or hypothermic (TH) conditions. Brain damage was assessed longitudinally at 24 h, 2 wk, and 12 wk. Motor function was assessed with the beam walk; recognition memory was measured by novel object recognition.

RESULTS

Neuroprotection with TH was apparent at 2 and 12 wk in both moderately and severely damaged animals. TH improved motor function in moderate, but not severe, damage. Impaired object recognition occurred with severe damage with no evidence of protection of TH.

CONCLUSION

This adaptation of the immature rat model of HI provides a reproducible platform to further study HIE/TH in which individual animals are followed up longitudinally to provide a useful translational preclinical model.

Mild hypothermia and hemorrhagic lesions in neonates with hypoxic-ischemic encephalopathy: experience in an outborn center

OBJECTIVE

Therapeutic hypothermia (TH) started within six hours from birth has been shown to improve neurodevelopmental outcomes in newborns with moderate-to-severe hypoxic-ischemic encephalopathy.

METHODS

Twenty-nine consecutive newborns treated with whole body cooling at the Bambino Gesú Children's Hospital between March 2011 and December 2012 were included in this study. All infants were out-born neonates. Passive cooling was always started at the birth center and continued during transportation. Pre- and post-transport risk index of physiological stability (TRIPS) scores were calculated for each patient to evaluate the impact of the transportation. Magnetic resonance imaging (MRI) was performed within 10 days of life to investigate the presence of brain injury.

RESULTS

Among the 26 survivors, 14 had no detectable lesions and 12 presented with brain injury on MRI. Four babies presented with cerebral bleeding. Babies with cerebral hemorrhage had a worse pre-transport TRIPS score, but among these neonates no worsening between pre and post-transport score was registered.

CONCLUSION

The presence of cerebral hemorrhagic lesions seemed to be related to the initial clinical conditions of the baby rather than to the transport itself. Our data confirm that TH performed in an out-born center is efficient and safe.

Brain imaging in cooled encephalopathic neonates does not differ between four and 11 days after birth

AIM

The optimal timing of magnetic resonance imaging (MRI) in encephalopathic infants treated with hypothermia is unknown, and this study examined whether early scans differed from later scans.

METHODS

We assessed paired MRI scans carried out on 41 cooled encephalopathic infants at a median of four and 11 days using two scoring systems: the Rutherford injury scores for the basal ganglia and thalami (BGT), white matter and the posterior limb of the internal capsule, and the Bonifacio injury scores for the BGT and watershed area.

RESULTS

Both systems produced consistent injury severity scores in 37 of 41 infants on both days, with Rutherford scores predicting poor outcome in six early scans and seven later scans (K = 0.91) and Bonifacio doing the same in seven and nine scans (K = 0.85). A white matter/watershed score of two or a BGT score of one indicated severe changes by day 11 in three infants, but lower scores did not.

CONCLUSION

Magnetic resonance imaging scans indicated that the Rutherford and Bonifacio systems produced similar scores in 37 of 41 cooled encephalopathic infants at a median of four and 11 days. Infants with an early white matter/watershed scores of two or a BGT score of one may worsen and should be rescanned.

Evolution of Apparent Diffusion Coefficient and Fractional Anisotropy in the Cerebrum of Asphyxiated Newborns Treated with Hypothermia over the First Month of Life

The objective of this study was to assess the evolution of diffusion-weighted imaging (DWI) and diffusion-tensor imaging (DTI) over the first month of life in asphyxiated newborns treated with hypothermia and to compare it with that of healthy newborns. Asphyxiated newborns treated with hypothermia were enrolled prospectively; and the presence and extent of brain injury were scored on each MRI. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured in the basal ganglia, in the white matter and in the cortical grey matter. Sixty-one asphyxiated newborns treated with hypothermia had a total of 126 ADC and FA maps. Asphyxiated newborns developing brain injury eventually had significantly decreased ADC values on days 2-3 of life and decreased FA values around day 10 and 1 month of life compared with those not developing brain injury. Despite hypothermia treatment, asphyxiated newborns may develop brain injury that still can be detected with advanced neuroimaging techniques such as DWI and DTI as early as days 2-3 of life. A study of ADC and FA values over time may aid in the understanding of how brain injury develops in these newborns despite hypothermia treatment.

Comparison of selective head cooling therapy and whole body cooling therapy in newborns with hypoxic ischemic encephalopathy: short term results

AIM

In this study, it was aimed to investigate which method was superior by applying selective head cooling or whole body cooling therapy in newborns diagnosed with moderate or severe hypoxic ischemic encephalopathy.

MATERIALS AND METHOD

Newborns above the 35th gestational age diagnosed with moderate or severe hypoxic ischemic encephalopathy were included in the study and selective head cooling or whole body cooling therapy was performed randomly. The newborns who were treated by both methods were compared in terms of adverse effects in the early stage and in terms of short-term results. Ethics committee approval was obtained for the study (06.01.2010/35).

RESULTS

Fifty three babies diagnosed with hypoxic ischemic encephalopathy were studied. Selective head cooling was applied to 17 babies and whole body cooling was applied to 12 babies. There was no significant difference in terms of adverse effects related to cooling therapy between the two groups. When the short-term results were examined, it was found that the hospitalization time was 34 (7-65) days in the selective head cooling group and 18 (7-57) days in the whole body cooling group and there was no significant difference between the two groups (p=0.097). Four patients in the selective head cooling group and two patients in the whole body cooling group were discharged with tracheostomy because of the need for prolonged mechanical ventilation and there was no difference between the groups in terms of discharge with tracheostomy (p=0.528). Five patients in the selective head cooling group and three patients in the whole body cooling group were discharged with a gastrostomy tube because they could not be fed orally and there was no difference between the groups in terms of discharge with a gastrostomy tube (p=0.586). One patient who was applied selective head cooling and one patient who was applied whole body cooling died during hospitalization and there was no difference between the groups in terms of mortality (p=0.665).

CONCLUSIONS

There is no difference between the methods of selective head cooling and whole body cooling in terms of adverse effects and short-term results.

MRI obtained during versus after hypothermia in asphyxiated newborns

OBJECTIVE

To assess whether the brain MRI results obtained during hypothermia identify the later brain injury observed in asphyxiated newborns after therapy is completed.

PATIENTS AND METHODS

Asphyxiated newborns treated with hypothermia were prospectively enrolled in this study if they had at least one MRI performed during hypothermia treatment and then another MRI performed around day 10 of life.

RESULTS

A total of 129 MRI scans were obtained from 43 asphyxiated newborns treated with hypothermia. Sixty per cent developed brain injury; all the brain injuries observed on the late scans were already present on day 2-3 of life during hypothermia, and the extent of injury was similar between the early and late scans. The brain MRI on day 2-3 of life had a sensitivity of 100% (95% CI 84% to 100%) and a specificity of 100% (95% CI 77% to 100%) to identify the presence and extent of later brain injury.

CONCLUSIONS

The brain MRIs performed during hypothermia already permit an accurate definition of the presence and extent of brain injury that later develop in asphyxiated newborns despite treatment. These results may have research and clinical implications for the care of these newborns.

Minimal systemic hypothermia combined with selective head cooling evaluated in a pig model of hypoxia-ischemia

BACKGROUND

Selective head cooling (SHC) with moderate hypothermia (HT) and whole-body cooling are beneficial following perinatal asphyxia. SHC with systemic normothermia (NT) or minimal HT is under-investigated, could obviate systemic complications of moderate HT, and be applicable to preterm infants. We hypothesized that minimal systemic HT with SHC following hypoxia-ischemia (HI) would be neuroprotective compared with systemic NT.

METHODS

Newborn pigs underwent global HI causing permanent brain injury before being randomized to NT (rectal temperature (Trectal) 38.5 °C) or minimal HT (Trectal 37.0 °C) with SHC (cooling cap and body wrap) for 48 h followed by 24-h NT with 72-h survival.

RESULTS

SHC did not reduce global or regional neuropathology score when correcting for insult severity or compared with a NT group matched for HI severity but increased mortality by 26%. During 48 h, the SHC mean ± SD Trectal was 37.0 ± 0.2 °C, and Tdeep brain and Tsuperficial brain were 35.0 ± 1.1 °C and 31.5 ± 1.6 °C, respectively, with stable Tbrain achieved ≥ 3 h after starting cooling.

CONCLUSION

This is the first study in newborn pigs of minimal systemic HT with SHC for 48 h and a further 24 h of NT following HI. Mortality was increased in the cooled group with no neuroprotection in survivors.

New insights into the developing rabbit brain using diffusion tensor tractography and generalized q-sampling MRI

The use of modern neuroimaging methods to characterize the complex anatomy of brain development at different stages reveals an enormous wealth of information in understanding this highly ordered process and provides clues to detect neurological and neurobehavioral disorders that have their origin in early structural and functional cerebral maturation. Non-invasive diffusion tensor magnetic resonance imaging (DTI) is able to distinguish cerebral microscopic structures, especially in the white matter regions. However, DTI is unable to resolve the complicated neural structure, i.e., the fiber crossing that is frequently observed during the maturation process. To overcome this limitation, several methods have been proposed. One such method, generalized q-sampling imaging (GQI), can be applied to a variety of datasets, including the single shell, multi-shell or grid sampling schemes that are believed to be able to resolve the complicated crossing fibers. Rabbits have been widely used for neurodevelopment research because they exhibit human-like timing of perinatal brain white matter maturation. Here, we present a longitudinal study using both DTI and GQI to demonstrate the changes in cerebral maturation of in vivo developing rabbit brains over a period of 40 weeks. Fractional anisotropy (FA) of DTI and generalized fractional anisotropy (GFA) of GQI indices demonstrated that the white matter anisotropy increased with age, with GFA exhibiting an increase in the hippocampus as well. Normalized quantitative anisotropy (NQA) of GQI also revealed an increase in the hippocampus, allowing us to observe the changes in gray matter as well. Regional and whole brain DTI tractography also demonstrated refinement in fiber pathway architecture with maturation. We concluded that DTI and GQI results were able to characterize the white matter anisotropy changes, whereas GQI provided further information about the gray matter hippocampus area. This developing rabbit brain DTI and GQI database could also be used for educational purposes and neuroscience investigations.

Does amplitude-integrated electroencephalogram background pattern correlate with cerebral injury in neonates with hypoxic-ischaemic encephalopathy?

AIMS

To determine the correlation between amplitude-integrated electroencephalogram (aEEG) background pattern and cerebral magnetic resonance imaging (MRI) in infants with hypoxic-ischaemic encephalopathy (HIE) and to examine whether the correlation changes with therapeutic hypothermia.

METHODS

We included 38 term-born infants with HIE of whom 17 were cooled. All were continuously monitored with aEEG. Background pattern was scored at the beginning and the end of the recording. Cerebral MRI was obtained on median day 5 (2-11 days). Abnormalities were classified using a predefined scoring system for basal ganglia, watershed and overall injury, and then grouped into mild-moderate and severe.

RESULTS

Abnormal aEEG background pattern correlated with more severe cerebral injury on MRI in the non-cooled infants (P < 0.01). In addition, cooled infants had less severe cerebral injury than non-cooled infants, in particular on T2-weighted images (watershed P = 0.04 and total injury score = 0.07).

CONCLUSIONS

Abnormal aEEG background pattern is predictive of abnormal MRI, but therapeutic hypothermia seems to reduce this association. Thus, when cooling is applied in a clinical setting, the predictive value of aEEG may be limited.

Stem cell therapy for neonatal hypoxic-ischemic encephalopathy

Treatments for neonatal hypoxic-ischemic encephalopathy (HIE) have been limited. The aim of this paper is to offer translational research guidance on stem cell therapy for neonatal HIE by examining clinically relevant animal models, practical stem cell sources, safety and efficacy of endpoint assays, as well as a general understanding of modes of action of this cellular therapy. In order to do so, we discuss the clinical manifestations of HIE, highlighting its overlapping pathologies with stroke and providing insights on the potential of cell therapy currently investigated in stroke, for HIE. To this end, we draw guidance from recommendations outlined in stem cell therapeutics as an emerging paradigm for stroke or STEPS, which have been recently modified to Baby STEPS to cater for the “neonatal” symptoms of HIE. These guidelines recognized that neonatal HIE exhibit distinct disease symptoms from adult stroke in need of an innovative translational approach that facilitates the entry of cell therapy in the clinic. Finally, new information about recent clinical trials and insights into combination therapy are provided with the vision that stem cell therapy may benefit from available treatments, such as hypothermia, already being tested in children diagnosed with HIE.

Electroencephalogram and magnetic resonance imaging comparison as a predicting factor for neurodevelopmental outcome in hypoxic ischemic encephalopathy infant treated with hypothermia

Hypoxic-ischemic encephalopathy (HIE) is an important cause of acute neurological damage in newborns at (or near) term. Several trials in recent years have shown that moderate hypothermia by total body cooling or selective head is an effective intervention to reduce mortality and major disability in infants survived a perinatal hypoxic-ischemic attack. Follow-up in these patients is very important to establish neurodevelopmental outcome, and specific markers can lead us to detect predicting sign for good or poor outcome. We reported a few cases of newborn with HIE treated with hypothermia, in whom the comparison between electroencephalogram (EEG) and magnetic resonance imaging (MRI) represents the first marker for neurodevelopment outcome prediction. The continuous EEG monitoring showed a depressed EEG activity with diffuse burst depression in 7 patients. No epileptic abnormalities were registered. In 10 out of 20 patients no abnormalities of the background activity and no epileptic abnormalities were observed. We found that a depressed EEG activity during the first 72 h of life and a diffused alteration of basal ganglia at MRI were correlated with a poor neurodevelopmental outcome at 18 months of follow-up.

Changes in amplitude-integrated electroencephalograms in piglets during selective mild head cooling after hypoxia-ischemia

BACKGROUND

Amplitude-integrated electroencephalogram (aEEG) is a simplified, alternative means of monitoring cerebral function and may be more useful clinically in some situations than conventional EEG. The aim of this study is to evaluate newborn piglets as an animal model to examine the effect of selective mild head cooling (HC) on aEEG after hypoxia-ischemia (HI).

METHODS

Thirty-four piglets were randomly allocated to the following treatment groups: normothermic control group (NC, n = 7), selective HC control group (HC, n = 9), normothermic HI group (NHI, n = 9), and selective HC HI group (SHC-HI, n = 9). HI was induced by temporary occlusion of both carotid arteries and simultaneous reduction of the concentration of inspired oxygen to 6% for 30 minutes. Mild hypothermia (35°C) was induced after HI using a HC cap and was maintained for 24 hours. Changes in aEEG were monitored for 6 days after these treatments and the incidence of abnormalities analyzed. Physiological parameters were also measured during this period.

RESULTS

In the two HI groups, animals exhibited severely abnormal aEEGs [continuous low voltage (CLV), burst-suppression, or flat tracing (FT)] 20 minutes after the beginning of HI. At 2 hours, the aEEG returned to normal in most of these animals. From 12 hours to 6 days, all animals in the NHI group exhibited severely abnormal aEEGs. Fewer animals in the SHC-HI group exhibited severe abnormal aEEGs during this time period, and four out of nine (44.4%) animals had continuous normal voltage (CNV) at 6 days.

CONCLUSIONS

Selective mild HC decreases the incidence of severe abnormal aEEGs at late times after HI in newborn piglets.

Therapeutic hypothermia in neonates and selective hippocampal injury on diffusion-weighted magnetic resonance imaging

BACKGROUND

Hippocampal injury is most often observed in conjunction with basal ganglia injury after hypoxia-ischemia in term newborns. Objective was to determine perinatal characteristics leading to selective hippocampal injury vs basal ganglia injury on diffusion-weighted imaging in term encephalopathic infants following intrapartum hypoxia-ischemia treated with selective head cooling and to correlate specific injury to subsequent neurodevelopmental outcome.

METHODS

Retrospective chart review of obstetric and/or perinatal risk factors and patient characteristics in term infants treated with selective head cooling. All infants met standard enrollment criteria for cooling. MRI was obtained at a median of 7 days of life. Abnormal outcome was defined as spastic quadriplegia, cognitive delay, both, or death.

RESULTS

Fifty-seven infants were included for analysis. Diffusion-weighted imaging findings included normal (n = 31), basal ganglia injury (n = 16), and selective hippocampal injury (n = 10). No differences in gestational age, birth weight, sex, or labor complications between groups. More infants in the basal ganglia vs hippocampal group required delivery room cardiopulmonary resuscitation (P = 0.05), exhibited persistent severe acidosis, severe amplitude electroencephalography suppression, and encephalopathy at birth (P < 0.05). Abnormal neurodevelopmental outcome or death was observed in 88% vs 10% of infants in the basal ganglia vs the hippocampal group, respectively (P = 0.0001).

CONCLUSIONS

Infants with hippocampal injury on diffusion-weighted imaging recovered from an intrapartum asphyxial insult more rapidly as reflected by an earlier correction of acid-base status, were less likely to need cardiopulmonary resuscitation, and were less severely encephalopathic. These findings highlight the exquisite vulnerability of the hippocampus to acute hypoxia unaffected by selective head cooling, whereas the normal appearance of the basal ganglia in these infants suggests a neuroprotective effect of cooling.

Risk factors for intraventricular hemorrhage in term asphyxiated newborns treated with hypothermia

BACKGROUND

Intraventricular hemorrhage is rare in term newborns. Severe asphyxia is recognized as one of the risk factors of intraventricular hemorrhage in these newborns. Therapeutic hypothermia, which is the only available treatment for the limitation of brain injury in term asphyxiated newborns, may cause fluctuations of cerebral blood flow, possibly placing the newborn more at risk for intraventricular hemorrhage. The literature regarding the incidence of intraventricular hemorrhage in the context of neonatal hypoxic-ischemic encephalopathy and hypothermia is sparse.

METHODS

We present a clinical observation and review the literature regarding the risk factors for intraventricular hemorrhage in term asphyxiated newborns treated with hypothermia.

RESULTS

We describe the clinical course of a term newborn with severe hypoxic-ischemic encephalopathy who developed significant intraventricular hemorrhage during the rewarming period after the 72-hour hypothermia.

CONCLUSION

This newborn presented several risk factors for intraventricular hemorrhage, including severe asphyxia, hemodynamic instability, hemostasis disturbances, instrument delivery, venous sinus thrombosis, and hypoglycemia. Hypothermia and rewarming also may have contributed by causing fluctuations in cerebral blood flow.

Predictive value of neonatal MRI showing no or minor degrees of brain injury after hypothermia

BACKGROUND

Magnetic resonance imaging is a surrogate biomarker for major neurodevelopmental disabilities in survivors of perinatal hypoxic-ischemic encephalopathy because injury to the basal ganglia/thalami is highly predictive of major neuromotor and cognitive problems. Major disabilities and the appearance of neonatal magnetic resonance imaging are improved with therapeutic hypothermia. We evaluated neurodevelopmental outcomes when conventional magnetic resonance imaging showed minimal or no brain injury.

METHODS

Institutional review board-approved series of 62 infants (≥36 weeks; ≥1800 g; 34 boys/28 girls) cooled for hypoxic-ischemic encephalopathy between 2005 and 2011 who underwent neonatal magnetic resonance imaging and Bayley Scales of Infant and Toddler Development-III at 22 ± 7 months of age. Magnetic resonance imaging at 5-14 (mean 8) days was scored as normal (score = 0), showing focal gray or white matter injury only (score = 1), or basal ganglia/thalamic and/or watershed lesions with or without more extensive hemispheric injury (score = 2). Sensitivity, specificity, and positive and negative predictive values for magnetic resonance scores 0 and 1 and statistical interaction between magnetic resonance imaging score and age at magnetic resonance imaging were determined.

RESULTS

Magnetic resonance score = 0 was seen in 35/62 patients; 26/35 (74%) were typically developing, seven (20%) had moderate and two (6%) had severe delay. Magnetic resonance score = 1 was seen in 17/62 (27%) patients; 5/17 (29%) were normal, 11/17 (65%) had moderate delay, and 1/17 (6%) had severe neurodevelopmental delay. Of the 52 patients with magnetic resonance scores of 0 and 1, 40% were abnormal. The negative predictive value of a normal magnetic resonance imaging was 74%. For score 1, sensitivity was 95% (confidence interval 63%-83%), specificity 84% (confidence interval 70%-90%), positive predictive value 84% (confidence interval 71%-93%), and negative predictive value 74% (confidence interval 62%-82%).

CONCLUSIONS

Caution is warranted when prognosticating about neurodevelopmental status in early childhood after hypoxic ischemic encephalopathy with cooling, and longer follow-up studies are needed to determine the prognostic significance of a neonatal magnetic resonance imaging showing no or minor degrees of brain injury.

Regional brain injury on conventional and diffusion weighted MRI is associated with outcome after pediatric cardiac arrest

BACKGROUND

To assess regional brain injury on magnetic resonance imaging (MRI) after pediatric cardiac arrest (CA) and to associate regional injury with patient outcome and effects of hypothermia therapy for neuroprotection.

METHODS

We performed a retrospective chart review with prospective imaging analysis. Children between 1 week and 17 years of age who had a brain MRI in the first 2 weeks after CA without other acute brain injury between 2002 and 2008 were included. Brain MRI (1.5 T General Electric, Milwaukee, WI, USA) images were analyzed by 2 blinded neuroradiologists with adjudication; images were visually graded. Brain lobes, basal ganglia, thalamus, brain stem, and cerebellum were analyzed using T1, T2, and diffusion-weighted images (DWI).

RESULTS

We examined 28 subjects with median age 1.9 years (IQR 0.4-13.0) and 19 (68 %) males. Increased intensity on T2 in the basal ganglia and restricted diffusion in the brain lobes were associated with unfavorable outcome (all P < 0.05). Therapeutic hypothermia had no effect on regional brain injury. Repeat brain MRI was infrequently performed but demonstrated evolution of lesions.

CONCLUSION

Children with lesions in the basal ganglia on conventional MRI and brain lobes on DWI within the first 2 weeks after CA represent a group with increased risk of poor outcome. These findings may be important for developing neuroprotective strategies based on regional brain injury and for evaluating response to therapy in interventional clinical trials.

Single dose recombinant erythropoietin versus moderate hypothermia for neonatal hypoxic ischemic encephalopathy in low resource settings

OBJECTIVE

To determine the safety and efficacy of single dose systemic recombinant human erythropoietin (rEPO) in neonates with perinatal hypoxic Ischemic Encephalopathy (HIE), and its effect on serum brain-derived neurotrophic factor (BDNF) and neuron-specific enolase (NSE).

METHODS

Forty-five full-term neonates; 30 with perinatal HIE and 15 controls were studied. HIE neonates were randomized into three intervention groups (first 6 h of life): 10 received single subcutaneous 1500 U/kg rEPO at day-1, 10 subjected to hypothermia for 72 h and 10 received supportive care. BDNF and NSE measured during first 6 h and day 5 postnatal. Daily Thompson's score, MRI brain and neuromuscular function scale for survivors at 3 months of age were done.

RESULTS

Hypothermia group had best survival especially with stage-II Sarnat scale, followed by rEpo and supportive group. BDNF day-5 was significantly higher in each group compared to controls. MRI score and neuromuscular function score were non-significantly lower in the hypothermia group compared to rEPO.

CONCLUSIONS

Therapeutic hypothermia was superior to single dose rEpo for neuro-protection in HIE especially in patients with stage-II Sarnat scale. Therapeutic effect of combined rEPO multiple dosing and modest hypothermia therapy should be studied.

Does clinical status 1 week after therapeutic hypothermia predict brain MRI abnormalities?

OBJECTIVE

Hypothermia improves clinical outcomes and brain magnetic resonance imaging (MRI) findings in infants with hypoxic-ischemic encephalopathy. We hypothesized that clinical status following hypothermia predicts brain MRI abnormalities, and helps determine which infants need an early MRI evaluation before discharge. The objective of this study was to determine whether the clinical evaluation 1 week after completion of 72 h of hypothermia treatment predicts the presence of brain MRI abnormalities related to hypoxia-ischemia.

STUDY DESIGN

The medical records of 83 consecutively cooled infants who underwent brain MRI were reviewed. Clinical evaluation by day 10 of life consisted of assessment of oral feeding ability, spontaneous activity, need for mechanical ventilation and a history of clinical seizures. Logistic regression analysis was performed using all four covariates, with an abnormal MRI as the primary outcome. Brain MRI with lesions in both the basal nuclei and the cortex was considered to be severely abnormal.

RESULT

MRI was abnormal in 46 (55%) infants. Univariate analysis identified all of the criteria as being significantly associated with an abnormal MRI. On multivariate analysis, only feeding difficulty (P<0.001, OR 9.5, 95% confidence interval (CI) 3 to 29.8) and a history of clinical seizures (P<0.001, OR 12, 95% CI 3 to 46.5) were significantly associated with an abnormal MRI. The areas under the receiver operating characteristic curve for feeding ability and seizure activity combined (0.86, 95% CI 0.77 to 0.94) indicated good accuracy with respect to the primary outcome. The negative predictive values of feeding difficulty and seizure activity for a severely abnormal MRI were 91% and 96%, respectively.

CONCLUSION

Infants who do not have a history of clinical seizures and who attained full oral feeding by 1 week after hypothermia are unlikely to have an abnormal brain MRI. This simple assessment provides significant prognostic information that can be useful in parental counseling, and may allow selective use of pre-discharge MRI.

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.

Hypoxic–ischemic brain injury and neuroprotection in the newborn infant

Recent clinical trials have confirmed that in term infants with moderate-to-severe hypoxic–ischemic encephalopathy, death and severe developmental disability can be reduced by early treatment with hypothermia. However, meta-analysis of these trials has confirmed that two-thirds of the survivors remain seriously impaired. The search for new neuroprotective interventions has therefore continued. Extensive research has identified the important biochemical pathways that result in neuronal loss, and the subsequent repair and regeneration processes. The most promising neuroprotective agents that limit the former, and promote the latter, are being tested in animal models of hypoxic–ischemic brain injury and are awaiting clinical trials. It is likely that a ‘cocktail’ of agents, affecting a number of pathways, will ultimately prove to be the most effective intervention. The latest additions to a long list of proposed substances are various stem cells that promote neurogenesis by releasing trophic substances into the injured brain. Future clinical trials are likely to employ early biomarkers, of which MRI and proton spectroscopy are probably the most predictive of long-term neurodevelopmental outcome. In conclusion, the exponential increase in knowledge in this field can be expected to provide many more neuroprotective agents within the next decade.