MRI obtained during versus after hypothermia in asphyxiated newborns

Insights from serial magnetic resonance imaging in neonatal encephalopathy in term infants

BACKGROUND

Limited serial neuroimaging studies use magnetic resonance imaging (MRI) to define the evolution of hypoxic-ischemic insults to the brain of term infants and encompass both the primary injury and its secondary impact on cerebral development. The optimal timing of MRI to fully evaluate the impact of hypoxic-ischemic encephalopathy on brain development and associated neurodevelopmental sequelae remains unknown.

METHODS

Goals: (a) review literature related to serial neuroimaging in term infants with HIE; (b) describe pilot data in two infants with HIE treated with therapeutic hypothermia who had a brain injury at day 3-5 and underwent four additional MRIs over the next 12 weeks of life and developmental evaluation at 24 months of age.

RESULTS

Early MRI defines primary injury on diffusion-weighted imaging, yet the full impact may not be fully apparent until after 1 month of life.

CONCLUSION

The full impact of an ischemic injury on the neonatal brain may not be fully visible until several weeks after the initial insult. This suggests the benefit of obtaining later time points for MRI to fully define the extent of injury and its neurodevelopmental impact.

IMPACT

Few studies inform the nature of the evolution of brain injury with hypothermia in HIE, limiting understanding of potential neuroprotection. MRI is the standard of care for prognosis in infants with HIE, however timing for optimal prognostic prediction remains unclear. Insights from MRI after the first week of life may assist in defining the full extent of brain injury and prognostic significance. A pilot study using five MRI timepoints up to 3 months of age, is presented. More data is required with a systematic evaluation of the impact of early brain injury on brain development in term infants with HIE following TH.

Quality improvement and outcomes for neonates with hypoxic-ischemic encephalopathy: obstetrics and neonatal perspectives

Despite significant improvement in perinatal care and research, hypoxic ischemic encephalopathy (HIE) remains a global healthcare challenge. From both published research and reports of QI initiatives, we have identified a number of distinct opportunities that can serve as targets of quality improvement (QI) initiatives focused on reducing HIE. Specifically, (i) implementation of perinatal interventions to anticipate and timely manage high-risk deliveries; (ii) enhancement of team training and communication; (iii) optimization of early HIE diagnosis and management in referring centers and during transport; (iv) standardization of the approach when managing neonates with HIE during therapeutic hypothermia; (v) and establishment of protocols for family integration and follow-up, have been identified as important in successful QI initiatives. We also provide a framework and examples of tools that can be used to support QI work and discuss some of the perceived challenges and future opportunities for QI targeting HIE.

Feasibility and Safety of Sildenafil to Repair Brain Injury Secondary to Birth Asphyxia (SANE-01): A Randomized, Double-blind, Placebo-controlled Phase Ib Clinical Trial

OBJECTIVE

To test feasibility and safety of administering sildenafil in neonates with neonatal encephalopathy (NE), developing brain injury despite therapeutic hypothermia (TH).

STUDY DESIGN

We performed a randomized, double-blind, placebo-controlled phase Ib clinical trial between 2016 and 2019 in neonates with moderate or severe NE, displaying brain injury on day-2 magnetic resonance imaging (MRI) despite TH. Neonates were randomized (2:1) to 7-day sildenafil or placebo (2 mg/kg/dose enterally every 12 hours, 14 doses). Outcomes included feasibility and safety (primary outcomes), pharmacokinetics (secondary), and day-30 neuroimaging and 18-month neurodevelopment assessments (exploratory).

RESULTS

Of the 24 enrolled neonates, 8 were randomized to sildenafil and 3 to placebo. A mild decrease in blood pressure was reported in 2 of the 8 neonates after initial dose, but not with subsequent doses. Sildenafil plasma steady-state concentration was rapidly reached, but decreased after TH discontinuation. Twelve percent of neonates (1/8) neonates died in the sildenafil group and 0% (0/3) in the placebo group. Among surviving neonates, partial recovery of injury, fewer cystic lesions, and less brain volume loss on day-30 magnetic resonance imaging were noted in 71% (5/7) of the sildenafil group and in 0% (0/3) of the placebo group. The rate of death or survival to 18 months with severe neurodevelopmental impairment was 57% (4/7) in the sildenafil group and 100% (3/3) in the placebo group.

CONCLUSIONS

Sildenafil was safe and well-absorbed in neonates with NE treated with TH. Optimal dosing needs to be established. Evaluation of a larger number of neonates through subsequent phases II and III trials is required to establish efficacy.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.govNCT02812433.

Left Ventricular Function and Dimensions Are Altered Early in Infants Developing Brain Injury in the Setting of Neonatal Encephalopathy

We evaluated the association between left cardiac 3-dimensional echocardiographic parameters and brain injury in a single-center prospective study of neonates with neonatal encephalopathy. On day 2 of life, neonates with brain injury had greater left ventricle end-diastolic and stroke volume but also greater peak global circumferential strain detected by 3-dimensional echocardiogram.

Correlation of Different MRI Scoring Systems with Long-Term Cognitive Outcome in Cooled Asphyxiated Newborns

(1) Background: Cerebral MRI plays a significant role in assessing the extent of brain injury in neonates with neonatal encephalopathy after perinatal asphyxia. Over the last decades, several MRI scoring systems were developed to enhance the predictive accuracy of MRI. The aim of this study was to validate the correlation of four established MRI scoring systems with cognitive long-term outcomes in cooled asphyxiated newborns. (2) Methods: Forty neonates with neonatal encephalopathy treated with therapeutic hypothermia were included in this retrospective study. The MRI scans from the second week of life were scored using four existing MRI scoring systems (Barkovich, NICHD, Rutherford, and Weeke). The patients' outcome was assessed with the Bayley Scales of Infant Development (BSID-III) at the age of 2 years. To evaluate the correlation between the MRI scoring system with the cognitive scores of BSID-III, the correlation coefficient was calculated for each scoring system. (3) Results: All four MRI scoring systems showed a significant correlation with the cognitive scores of BSID-III. The strongest correlation was found between the Weeke Score (r2 = 0.43), followed by the Rutherford score (r2 = 0.39), the NICHD score (r2 = 0.22), and the Barkovich score (r2 = 0.17). (4) Conclusion: Our study confirms previously published results in an independent cohort and indicates that the Weeke and Rutherford scores have the strongest correlation with the cognitive score of BSID-III in cooled asphyxiated newborns.

Long-term consequences of neonatal encephalopathy in the hypothermia era: protocol for a follow-up cohort study at 9 years of age

INTRODUCTION

Therapeutic hypothermia (TH) became the standard of care treatment for neonates with moderate and severe neonatal encephalopathy (NE) in most industrialized countries about 10 years ago. Although TH is effective in reducing mortality and the incidence of severe developmental disabilities, the recent literature converges in reporting frequent cognitive and behavioural difficulties at school entry in children with NE-TH. Although these challenges are deemed minor compared with cerebral palsy and intellectual disability, their impacts on a child's self-determination and family's well-being are quite significant. Therefore, the nature and extent of these difficulties need to be comprehensively described so that appropriate care can be offered.

METHODS AND ANALYSIS

The current study will be the largest follow-up study of neonates with NE treated with TH to characterize their developmental outcomes and associated brain structural profiles at 9 years of age. Specifically, we will compare executive function, attention, social cognition, behaviour, anxiety, self-esteem, peer problems, brain volume, cortical features, white matter microstructure and myelination between children with NE-TH and matched peers without NE. Associations of perinatal risk factors and structural brain integrity with cognitive, behavioural and psycho-emotional deficits will be evaluated to inform about the potential aggravating and protective factors associated with function.

ETHICS AND DISSEMINATION

This study is supported by the Canadian Institute of Health Research (202203PJT-480065-CHI-CFAC-168509), and received approval from the Pediatric Ethical Review Board of the McGill University Health Center (MP-37-2023-9320). The study findings will be disseminated in scientific journals and conferences and presented to parental associations and healthcare providers to inform best practices.

TRIAL REGISTRATION NUMBER

NCT05756296.

Variations in care of neonates during therapeutic hypothermia: call for care practice bundle implementation

BACKGROUND

Therapeutic hypothermia (TH) is the gold-standard treatment for moderate and severe neonatal encephalopathy (NE). Care during TH has implications for long-term outcomes. Outcome variability exists among neonatal intensive care units (NICUs) in Canada, but care variations are not understood well. This study examines variations in care practices for neonates with NE treated with TH in NICUs across Canada.

METHODS

A non-anonymous, web-based questionnaire was emailed to tertiary NICUs in Canada providing TH for NE to assess care practices during the first days of life and neurodevelopmental follow-up.

RESULTS

Ninety-two percent (24/26) responded. Centres followed national guidelines regarding the use of the modified Sarnat score to assess the initial severity of NE, the need to initiate TH within the first 6 h of birth, and the importance of follow-up. However, other practices varied, including ventilation mode, definition/treatment of hypotension, routine echocardiography, use of sedation, use of electroencephalogram (EEG), MRI timing, placental analysis, and follow-up duration.

CONCLUSIONS

NICUs across Canada follow available national guidelines, but variations exist in practices for managing NE during TH. Development and implementation of a consensus-based care bundle for neonates during TH may reduce practice variability and improve outcomes.

IMPACT

This survey describes the current HIE care practices and variation among tertiary centres in Canada. Variations exist in the care of neonates with NE treated with TH in NICUs across Canada. This paper Identifies areas of variation that are not discussed in detail in the national guidelines and will help to set up quality improvement initiatives. Elucidating the variation in care practices calls for the creation and implementation of a national, consensus-based care bundle, with the objective to improve the outcomes of these critically ill neonates.

Discussing brain magnetic resonance imaging results for neonates with hypoxic-ischemic encephalopathy treated with hypothermia: A challenge for clinicians and parents

Context

Clinicians use brain magnetic resonance imaging (MRI) to discuss neurodevelopmental prognosis with parents of neonates with hypoxic-ischemic encephalopathy (HIE) treated with therapeutic hypothermia (TH).

Purpose

To investigate how clinicians and parents discuss these MRI results in the context of HIE and TH and how these discussions could be facilitated and more meaningful for parents.

Procedures

Mixed-methods surveys with open-ended and closed-ended questions were completed by two independent groups. (1) Clinicians responded to clinical vignettes of neonates with HIE treated with TH with various types of clinical features, evolution and extent of brain injury and questions about how they discuss brain MRI results in this context. (2) Parents of children with HIE treated with TH responded to questions about the discussion of MRI that they had while still in the neonatal intensive care unit and were asked to place it in perspective with the outcomes of their child when he/she reached at least 2 years of age. Open-ended responses were analyzed using a thematic analysis approach. Closed-ended responses are presented descriptively.

Results

Clinicians reported uncertainty, lack of confidence, and limitations when discussing brain MRI results in the context of HIE and TH. Brain MRI results were "usually" (53%) used in the prognostication discussion. When dealing with day-2 brain MRIs performed during TH, most clinicians (40%) assumed that the results of these early MRIs were only "sometimes" accurate and only used them "sometimes" (33%) to discuss prognosis; a majority of them (66%) would "always" repeat imaging at a later time-point to discuss prognosis. Parents also struggled with this uncertainty, but did not discuss limitations of MRI as often. Parents raised the importance of the setting where the discussion took place and the importance to inform them as quickly as possible. Clinicians identified strategies to improve these discussions, including interdisciplinary approach, formal training, and standardized approach to report brain MRI. Parents highlighted the importance of communication skills, the stress, the hope surrounding their situation, and the need to receive answers as soon as possible. The importance of showing the pictures or making representative drawing of the injury, but also highlighting the not-injured brain, was also highlighted by parents.

Conclusions

Discussing brain MRI results for neonates with HIE treated with TH are challenging tasks for clinicians and daunting moments for parents.

A novel scoring system (YASHMA) predicting brain injury in asphyxiated newborns

BACKGROUND

Hypoxic-ischemic encephalopathy is a complication of adverse intrapartum events and birth asphyxia resulting in brain injury and mortality in late preterm and term newborns.

OBJECTIVES

In this study, we aimed to predict brain damage on magnetic resonance imaging (MRI) with a new scoring system.

METHODS

Yieldly And Scorable Holistic Measuring of Asphyxia (YASHMA) is generated for detection of brain injury in asphyxiated newborns. Total scores were calculated according to scores of birth weight, gestation weeks, APGAR scores at first and fifth minutes, aEEG patterns and epileptic status of patients. The major outcome of the scoring system was to determine correlation between poor scores and neonatal brain injury detected on MRI.

RESULTS

In hypothermia group with brain injury, low gestational weeks and lowest APGAR scores, abnormal aEEG findings were statistically different from others. YASHMA scores were statistically significant with high sensitivity, specificity, AUC and 95% confidence interval values.

CONCLUSIONS

YASHMA scoring system is feasible and can be suggestive for detecting brain injury in low-income countries.

Recent advances in diagnostics of neonatal hypoxic ischemic encephalopathy

The prognosis in neonatal hypoxic ischemic encephalopathy (HIE) depends on early differential diagnosis for justified administration of emergency therapeutic hypothermia. The moment of therapy initiation directly affects the long-term neurological outcome: the earlier the commencement, the better the prognosis. This review analyzes recent advances in systems biology that facilitate early differential diagnosis of HIE as a pivotal complement to clinical indicators. We discuss the possibilities of clinical translation for proteomic, metabolomic and extracellular vesicle patterns characteristic of HIE and correlations with severity and prognosis. Identification and use of selective biomarkers of brain damage in neonates during the first hours of life is hindered by systemic effects of hypoxia. Chromatography– mass spectrometry blood tests allow analyzing hundreds and thousands of metabolites in a small biological sample to identify characteristic signatures of brain damage. Clinical use of advanced analytical techniques will facilitate the accurate and timely diagnosis of HIE for enhanced management.

Effects of Tissue Temperature and Injury on ADC during Therapeutic Hypothermia in Newborn Hypoxic-Ischemic Encephalopathy

BACKGROUND AND PURPOSE

ADC changes are useful in detecting ischemic brain injury, but mechanisms other than tissue pathology may affect the kinetic movement and diffusion of water molecules. We aimed to determine the effects of brain temperature on the corresponding ADC in infants undergoing therapeutic hypothermia.

MATERIALS AND METHODS

Brain temperature and ADC values in the basal ganglia, thalamus, cortical GM, and WM were analyzed during and after therapeutic hypothermia. The study cohort was categorized as having no-injury or injury. Among infants without injury, the correlation between ADC values and temperature was analyzed using the Pearson correlation. Intrasubject comparison of ADC changes during and after therapeutic hypothermia were analyzed, excluding patients who had an MR image interval of >5 days to minimize the effects of injury evolution.

RESULTS

Thirty-nine infants with hypoxic-ischemic encephalopathy were enrolled (23 no-injury; 16 injury). The median ADC was significantly lower during therapeutic hypothermia (837; interquartile range, 771-928, versus 906; interquartile range, 844-1032 ×10^-6mm²/s; P < .001). There was no difference in the ADC between the no-injury and injury groups during therapeutic hypothermia (823; interquartile range, 782-868, versus 842; interquartile range, 770-1008 ×10^-6mm²/s; P  = .4). In the no-injury group, in which ADC is presumed least affected by the evolution of injury, the median ADC was significantly lower during therapeutic hypothermia (826; interquartile range, 771-866, versus 897; interquartile range, 846-936 ×10^-6mm²/s; P  < .001). There was a moderate correlation between temperature and ADC in the no-injury group (during therapeutic hypothermia: Spearman ρ, 0.48; P  < .001; after therapeutic hypothermia: ρ, 0.4; P  < .001).

CONCLUSIONS

Aside from brain injury, reduced tissue temperature may also contribute to diffusion restriction on MR imaging in infants undergoing therapeutic hypothermia.

Asphyxiated Neonates Treated with Hypothermia: Birth Place Matters

OBJECTIVE

This study aimed to assess whether the hospital level of care where asphyxiated neonates treated with hypothermia were originally born influences their outcome.

STUDY DESIGN

We conducted a retrospective cohort study of all asphyxiated neonates treated with hypothermia in a large metropolitan area. Birth hospitals were categorized based on provincially predefined levels of care. Primary outcome was defined as death and/or brain injury on brain magnetic resonance imaging (adverse outcome) and was compared according to the hospital level of care.

RESULTS

The overall incidence of asphyxiated neonates treated with hypothermia significantly decreased as hospital level of care increased: 1 per 1,000 live births (109/114,627) in level I units; 0.9 per 1,000 live births (73/84,890) in level II units; and 0.7 per 1,000 live births (51/71,093) in level III units (p < 0.001). The rate of emergent cesarean sections and the initial pH within the first hour of life were significantly lower in level I and level II units compared with level III units (respectively, p < 0.001 and p = 0.002). In a multivariable analysis adjusting for the rates of emergent cesarean sections and initial pH within the first hour of life, being born in level I units was confirmed as an independent predictor of adverse outcome (adjusted odds ratio [OR] level I vs. level III 95% confidence interval [CI]: 2.13 [1.02-4.43], p = 0.04) and brain injury (adjusted OR level I vs. level III 95% CI: 2.41 [1.12-5.22], p = 0.02).

CONCLUSION

Asphyxiated neonates born in level I units and transferred for hypothermia treatment were less often born by emergent cesarean sections, had worse pH values within the first hour of life, and had a higher incidence of adverse outcome and brain injury compared with neonates born in level III units. Further work is needed to optimize the initial management of these neonates to improve outcomes, regardless of the location of their hospital of birth.

KEY POINTS

· The incidence of asphyxiated neonates treated with hypothermia varied by hospital level of care.. · Their rates of emergent cesarean sections and their initial pH within the first hour of life varied by hospital level of care.. · The hospital level of care was an independent predictor of their adverse outcome, defined as death and/or brain injury on brain MRI..

Proposing a care practice bundle for neonatal encephalopathy during therapeutic hypothermia

Neonates with neonatal encephalopathy (NE) often present with multi-organ dysfunction that requires multidisciplinary specialized management. Care of the neonate with NE is thus complex with interaction between the brain and various organ systems. Illness severity during the first days of birth, and not only during the initial hypoxia-ischemia event, is a significant predictor of adverse outcomes in neonates with NE treated with therapeutic hypothermia (TH). We thus propose a care practice bundle dedicated to support the injured neonatal brain that is based on the current best evidence for each organ system. The impact of using such bundle on outcomes in NE remains to be demonstrated.

Neuroimaging in the term newborn with neonatal encephalopathy

Neuroimaging is widely used to aid in the diagnosis and clinical management of neonates with neonatal encephalopathy (NE). Yet, despite widespread use clinically, there are few published guidelines on neuroimaging for neonates with NE. This review outlines the primary patterns of brain injury associated with hypoxic-ischemic injury in neonates with NE and their frequency, associated neuropathological features, and risk factors. In addition, it provides an overview of neuroimaging methods, including the most widely used scoring systems used to characterize brain injury in these neonates and their utility as predictive biomarkers. Last, recommendations for neuroimaging in neonates with NE are presented.

Early Versus Late Brain Magnetic Resonance Imaging after Neonatal Hypoxic Ischemic Encephalopathy Treated with Therapeutic Hypothermia

OBJECTIVE

To evaluate the agreement in brain injury findings between early and late magnetic resonance imaging (MRI) in newborn infants with hypoxic-ischemic encephalopathy treated with therapeutic hypothermia and to compare the ability of early vs late MRI to predict early neurodevelopmental outcomes.

STUDY DESIGN

This was a prospective longitudinal study of 49 patients with hypoxic-ischemic encephalopathy who underwent therapeutic hypothermia and had MRI performed at both <7 and ≥7 days of age. MRIs were reviewed by an experienced neuroradiologist and assigned brain injury severity scores according to established systems. Scores for early and late MRIs were assessed for agreement using the kappa statistic. The ability of early and late MRI scores to predict death or developmental delay at 15-30 months of age was assessed by logistic regression analyses.

RESULTS

Agreement between the early and late MRI was substantial to near perfect (k > 0.75, P < .001) across MRI scoring systems. In cases of discrepant scoring, early MRI was more likely to identify severe injury when compared with late MRI. Early MRI scores were more consistently predictive of adverse outcomes compared with late MRI.

CONCLUSIONS

The results of this study suggest that a single MRI performed in the first week after birth is adequate to assess brain injury and offer prognostic information in this high-risk population.

Myelination may be impaired in neonates following birth asphyxia

•

Myelination is a developmental process that intensifies after birth during the first years of life.

•

We used a T2* mapping sequence to assess myelination in healthy and critically ill neonates with neonatal encephalopathy.

•

Birth asphyxia, in addition to causing the previously well-described direct injury to the brain, may impair myelination.

Background

Myelination is a developmental process that begins during the end of gestation, intensifies after birth over the first years of life, and continues well into adolescence. Any event leading to brain injury around the time of birth and during the perinatal period, such as birth asphyxia, may impair this critical process. Currently, the impact of such brain injury related to birth asphyxia on the myelination process is unknown.

Objective

To assess the myelination pattern over the first month of life in neonates with neonatal encephalopathy (NE) developing brain injury, compared to neonates without injury (i.e., healthy neonates and neonates with NE who do not develop brain injury).

Methods

Brain magnetic resonance imaging (MRI) was performed around day of life 2, 10, and 30 in healthy neonates and near-term/term neonates with NE who were treated with hypothermia. We evaluated myelination in various regions of interest using a T2* mapping sequence. In each region of interest, we compared the T2* values of the neonates with NE with brain injury to the values of the neonates without injury, according to the MRI timing, by using a repeated measures generalized linear mixed model.

Results

We obtained 74 MRI scans over the first month of life for 6 healthy neonates, 17 neonates with NE who were treated with hypothermia and did not develop brain injury, and 16 neonates with NE who were treated with hypothermia and developed brain injury. The T2* values significantly increased in the neonates with NE who developed injury in the posterior limbs of the internal capsule (day 2: p < 0.001; day 10: p < 0.001; and day 30: p < 0.001), the thalami (day 2: p = 0.001; day 10: p = 0.006; and day 30: p = 0.016), the lentiform nuclei (day 2: p = 0.005), the anterior white matter (day 2: p = 0.002; day 10: p = 0.006; and day 30: p = 0.002), the posterior white matter (day 2: p = 0.001; day 10: p = 0.008; and day 30: p = 0.03), the genu of the corpus callosum (day 2: p = 0.01; and day 10: p = 0.006), and the optic radiations (day 30: p < 0.001).

Conclusion

In the neonates with NE who were treated with hypothermia and developed brain injury, birth asphyxia impaired myelination in the regions that are myelinated at birth or soon after birth (the posterior limbs of internal capsule, the thalami, and the lentiform nuclei), in the regions where the myelination process begins only after the perinatal period (optic radiations), and in the regions where this process does not occur until months after birth (anterior/posterior white matter), which suggests that birth asphyxia, in addition to causing the previously well-described direct injury to the brain, may impair myelination.

Cerebrospinal fluid levels of neuron-specific enolase predict the severity of brain damage in newborns with neonatal hypoxic-ischemic encephalopathy treated with hypothermia

Objectives

To investigate whether cerebrospinal fluid levels of neuron-specific enolase (CSF-NSE) during the first 72 hours correlate with other tools used to assess ongoing brain damage, including clinical grading of hypoxic-ischemic encephalopathy (HIE), abnormal patterns in amplitude integrated electroencephalography (aEEG), and magnetic resonance imaging (MRI), as well as with the neurodevelopmental outcomes at two years of age.

Material and methods

Prospective observational study performed in two hospitals between 2009 and 2011. Forty-three infants diagnosed with HIE within 6 hours of life were included. HIE was severe in 20 infants, moderate in 12, and mild in 11. Infants with moderate-to-severe HIE received whole-body cooling. Both the HIE cohort and a control group of 59 infants with suspected infection underwent measurement of CSF-NSE concentrations at between 12 and 72 hours after birth. aEEG monitoring was started at admission and brain MRI was performed within the first 2 weeks. Neurodevelopment was assessed at 24 months.

Results

The HIE group showed higher levels of CSF-NSE than the control group: median 70 ng/ml (29; 205) vs 10.6 ng/ml (7.7; 12.9); p <0.001. Median levels of CSF-NSE in infants with severe, moderate, and mild HIE were 220.5 ng/ml (120.5; 368.8), 45.5 ng/ml (26, 75.3), and 26 ng/ml (18, 33), respectively. CSF-NSE levels correlated were significantly higher in infants with seizures, abnormal aEEG, or abnormal MRI, compared to those without abnormalities. Infants with an adverse outcome showed higher CSF-NSE levels than those with normal findings (p<0.001), and the most accurate CSF-NSE cutoff level for predicting adverse outcome in the whole cohort was 108 ng/ml and 50ng/ml in surviving infants.

Conclusions

In the era of hypothermia, CSF-NSE concentrations provides valuable information as a clinical surrogate of the severity of hypoxic-ischemic brain damage, and this information may be predictive of abnormal outcome at two years of age.

Neonates with hypoxic-ischemic encephalopathy treated with hypothermia: Observations in a large Canadian population and determinants of death and/or brain injury

BACKGROUND

Birth asphyxia in term neonates remains a serious condition that causes significant mortality and long-term neurodevelopmental sequelae despite hypothermia treatment. The objective of this study was to review therapeutic hypothermia practices in a large population of neonates with hypoxic-ischemic encephalopathy (HIE) across Canada and to identify determinants of adverse outcome.

METHODS

Our retrospective observational cohort study examined neonates≥36 weeks, admitted to the Canadian Neonatal Network NICUs between 2010 and 2014, diagnosed with HIE, and treated with hypothermia. Adverse outcome was defined as death and/or brain injury. Maternal, birth, and postnatal characteristics were compared between neonates with adverse outcome and those without. The association between the variables which were significantly different (p < 0.05) between the two groups and adverse outcome were further tested, while adjusting for gestational age, birth weight, gender, and initial severity of encephalopathy.

RESULTS

A total of 2187 neonates were admitted for HIE; 52% were treated with hypothermia and 40% developed adverse outcome. Initial severity of encephalopathy (moderate, p = 0.006; severe, p < 0.0001), hypotension treated with inotropes (p = 0.001), and renal failure (p = 0.007) were significantly associated with an increased risk of death and/or brain injury.

CONCLUSIONS

In asphyxiated neonates treated with hypothermia, not only their initial severity of encephalopathy on admission, but also their cardiac and renal complications during the first days after birth were significantly associated with risk of death and/or brain injury. Careful monitoring and cautious management of these complications is warranted.

Neuron-Specific Enolase in Cerebrospinal Fluid Predicts Brain Injury After Sudden Unexpected Postnatal Collapse

BACKGROUND

Biomarkers of brain injury with high predictive value in newborns in critical neurological status are increasingly required. Neuron-specific enolase in cerebrospinal fluid has been shown to be highly predictive in newborns with perinatal hypoxic-ischemic encephalopathy, but its utility has not been examined in sudden unexpected postnatal collapse.

PURPOSE

We analyzed whether the levels of neuron-specific enolase in cerebrospinal fluid can be a useful biomarker to estimate the severity of brain injury in neonates after a sudden unexpected postnatal collapse.

METHODS

This is a prospective observational study of near-term infants who were consecutively admitted with sudden unexpected postnatal collapse in two neonatal intensive care units during a nine-year period. Variables were collected and analyzed regarding the perinatal period, clinical course, severity of encephalopathy, amplitude-integrated encephalography, magnetic resonance imaging findings, and outcome. Neuron-specific enolase in cerebrospinal fluid samples were obtained in 18 infants with sudden unexpected postnatal collapse between 12 and 72 hours after the collapse and compared with those of 29 controls.

RESULTS

The levels of neuron-specific enolase in cerebrospinal fluid were higher in patients than in controls (P < 0.001). Levels of neuron-specific enolase in cerebrospinal fluid in infants with sudden unexpected postnatal collapse were significantly higher in patients who presented severe encephalopathy, seizures, abnormal amplitude-integrated encephalography background, or brain injury on magnetic resonance imaging. Receiver operator characteristic curve analysis revealed a neuron-specific enolase in cerebrospinal fluid cutoff value of maximum predictive accuracy of 61 ng/mL (area under the curve, 1.0; sensitivity, specificity, positive predictive value, and negative predictive value, 100%) for identifying infants who died or had adverse outcomes.

CONCLUSIONS

Levels of neuron-specific enolase in cerebrospinal fluid obtained between 12 and 72 hours after a sudden unexpected postnatal collapse event seem to be a useful biomarker for identifying newborns with severe brain injury and for predicting outcome.

Neurodevelopmental effect of intracranial hemorrhage observed in hypoxic ischemic brain injury in hypothermia-treated asphyxiated neonates - an MRI study

BACKGROUND

Identification of early signs of hypoxic ischemic encephalopathy (HIE) with magnetic resonance imaging (MRI) has proven of prognostic significance. Yet, the importance of intracranial hemorrhage (ICH), being present concomitantly had not been investigated yet, despite the known influence of hypothermia on hemostasis. We aimed to determine whether presence of ICH on MRI alongside the signs of HIE have an impact on prognosis in neonates with the clinical diagnosis of HIE.

METHODS

A retrospective study of consecutively sampled 108 asphyxiated term infants admitted to a tertiary neonatal intensive care unit (between 2007 and 2016), treated with whole body hypothermia and having brain MRI within 1 week of life was conducted. Presence or absence of HIE signs on MRI (basal ganglia-thalamus, watershed pattern and total brain injury) and on MR spectroscopy (lactate peak with decreased normal metabolites measured by Lac/NAA ratio) and/or of the five major types of ICH were recorded. Neurodevelopmental outcome was measured with Bayley Scales of Infant Development-II (BSID-II) test. Death or abnormal neurodevelopment (BSID-II score < 85) was defined as poor outcome in Chi-square test. Multivariate logistic regression analysis was performed on survivors.

RESULTS

MRI and MR-spectroscopy (MRS) signs of HIE were present in 72% (n = 78). 36% (n = 39) of neonates had ICH, being mainly small in size. Chi-square test showed a relationship between neurodevelopmental outcome and initial MRI. Unadjusted logistic regression showed that neonates presenting MRI and MRS signs of HIE have 6.23 times higher odds for delayed mental development (OR = 6.2292; CI95% = [1.2642; 30.6934], p = 0.0246), than infants without imaging alterations; with no ICH effect on outcome. Adjustment for clinical and imaging parameters did not change the pattern of results, i.e. HIE remained an independent risk factor for delayed neurodevelopment (OR = 6.2496; CI95% = [1.2018; 32.4983], p = 0.0294), while ICH remained to have no significant effect.

CONCLUSION

HIE related MRI abnormalities proved to be important prognostic factors of poor outcome in cooled asphyxiated infants when present, suggesting that early MRI with MRS is beneficial for prognostication. Interestingly, ICHs present in about one third of all cases had no significant effect on neurodevelopmental outcome, despite the known hemostasis altering effects of hypothermia.

Changes in brain perfusion in successive arterial spin labeling MRI scans in neonates with hypoxic-ischemic encephalopathy

The primary objective of this study was to evaluate changes in cerebral blood flow (CBF) using arterial spin labeling MRI between day 4 of life (DOL4) and day 11 of life (DOL11) in neonates with hypoxic-ischemic encephalopathy (HIE) treated with hypothermia. The secondary objectives were to compare CBF values between the different regions of interest (ROIs) and between infants with ischemic lesions on MRI and infants with normal MRI findings. We prospectively included all consecutive neonates with HIE admitted to the neonatal intensive care unit of our institution who were eligible for therapeutic hypothermia. Each neonate systematically underwent two MRI examinations as close as possible to day 4 (early MRI) and day 11 (late MRI) of life. A custom processing pipeline of morphological and perfusion imaging data adapted to neonates was developed to perform automated ROI analysis. Twenty-eight neonates were included in the study between April 2015 and December 2017. There were 16 boys and 12 girls. Statistical analysis was finally performed on 37 MRIs, 17 early MRIs and 20 late MRIs. Eleven neonates had both early and late MRIs of good quality available. Eight out of 17 neonates (47%) had an abnormal on late MRI as performed and 7/20 neonates (35%) had an abnormal late MRI. CBF values in the basal ganglia and thalami (BGT) and temporal lobes were significantly higher on DOL4 than on DOL11. There were no significant differences between DOL4 and DOL11 for the other ROIs. CBF values were significantly higher in the BGT vs. the cortical GM, on both DOL4 and DOL11. On DOL4, the CBF was significantly higher in the cortical GM, the BGT, and the frontal and parietal lobes in subjects with an abnormal MRI compared to those with a normal MRI. On DOL11, CBF values in each ROI were not significantly different between the normal MRI group and the abnormal MRI group, except for the temporal lobes. This article proposes an innovative processing pipeline for morphological and ASL data suited to neonates that enable automated segmentation to obtain CBF values over ROIs. We evaluate CBF on two successive scans within the first 15 days of life in the same subjects. ASL imaging in asphyxiated neonates seems more relevant when used relatively early, in the first days of life. The correlation of intra-subject changes in cerebral perfusion between early and late MRI with neurodevelopmental outcome warrants investigation in a larger cohort, to determine whether the CBF pattern change can provide prognostic information beyond that provided by visible structural abnormalities on conventional MRI.

Cerebral oxygen metabolism during and after therapeutic hypothermia in neonatal hypoxic-ischemic encephalopathy: a feasibility study using magnetic resonance imaging

BACKGROUND

Therapeutic hypothermia is the standard-of-care treatment for infants diagnosed with moderate-to-severe hypoxic-ischemic encephalopathy (HIE). MRI for assessing brain injury is usually performed after hypothermia because of logistical challenges in bringing acutely sick infants receiving hypothermia from the neonatal intensive care unit (NICU) to the MRI suite. Perhaps examining and comparing early cerebral oxygen metabolism disturbances to those after rewarming will lead to a better understanding of the mechanisms of brain injury in HIE and the effects of therapeutic hypothermia.

OBJECTIVE

The objectives were to assess the feasibility of performing a novel T2-relaxation under spin tagging (TRUST) MRI technique to measure venous oxygen saturation very early in the time course of treatment, 18-24 h after the initiation of therapeutic hypothermia, to provide a framework to measure neonatal cerebral oxygen metabolism noninvasively, and to compare parameters between early and post-hypothermia MRIs.

MATERIALS AND METHODS

Early (18-24 h after initiating hypothermia) MRIs were performed during hypothermia treatment in nine infants with HIE (six with moderate and three with severe HIE). Six infants subsequently had an MRI after hypothermia. Mean values of cerebral blood flow, oxygen extraction fraction, and cerebral metabolic rate of oxygen from MRIs during hypothermia were compared between infants with moderate and severe HIE; and in those with moderate HIE, we compared cerebral oxygen metabolism parameters between MRIs performed during and after hypothermia.

RESULTS

During the initial hypothermia MRI at 23.5±5.2 h after birth, infants with severe HIE had lower oxygen extraction fraction (P=0.04) and cerebral metabolic rate of oxygen (P=0.03) and a trend toward lower cerebral blood flow (P=0.33) compared to infants with moderate HIE. In infants with moderate HIE, cerebral blood flow decreased and oxygen extraction fraction increased between MRIs during and after hypothermia (although not significantly); cerebral metabolic rate of oxygen (P=0.93) was not different.

CONCLUSION

Early MRIs were technically feasible while maintaining hypothermic goal temperatures in infants with HIE. Cerebral oxygen metabolism early during hypothermia is more disturbed in severe HIE. In infants with moderate HIE, cerebral blood flow decreased and oxygen extraction fraction increased between early and post-hypothermia scans. A comparison of cerebral oxygen metabolism parameters between early and post-hypothermia MRIs might improve our understanding of the evolution of HIE and the benefits of hypothermia. This approach could guide the use of adjunctive neuroprotective strategies in affected infants.

Cerebral Lactate Concentration in Neonatal Hypoxic-Ischemic Encephalopathy: In Relation to Time, Characteristic of Injury, and Serum Lactate Concentration

Background

Cerebral lactate concentration can remain detectable in neonatal hypoxic-ischemic encephalopathy (HIE) after hemodynamic stability. The temporal resolution of regional cerebral lactate concentration in relation to the severity or area of injury is unclear. Furthermore, the interplay between serum and cerebral lactate in neonatal HIE has not been well defined. The study aims to describe cerebral lactate concentration in neonatal HIE in relation to time, injury, and serum lactate.

Design/methods

Fifty-two newborns with HIE undergoing therapeutic hypothermia (TH) were enrolled. Magnetic resonance imaging and spectroscopy (MRI + MR spectroscopy) were performed during and after TH at 54.6 ± 15.0 and 156 ± 57.6 h of life, respectively. Severity and predominant pattern of injury was scored radiographically. Single-voxel ¹H MR spectra were acquired using short-echo (35 ms) PRESS sequence localized to the basal ganglia (BG), thalamus (Thal), gray matter (GM), and white matter. Cerebral lactate concentration was quantified by LCModel software. Serum and cerebral lactate concentrations were plotted based on age at time of measurement. Multiple comparisons of regional cerebral lactate concentration based on severity and predominant pattern of injury were performed. Spearman's Rho was computed to determine correlation between serum lactate and cerebral lactate concentration at the respective regions of interest.

Results

Overall, serum lactate concentration decreased over time. Cerebral lactate concentration remained low for less severe injury and decreased over time for more severe injury. Cerebral lactate remained detectable even after TH. During TH, there was a significant higher concentration of cerebral lactate at the areas of injury and also when injury was more severe. However, these differences were no longer observed after TH. There was a weak correlation between serum lactate and cerebral lactate concentration at the BG (r_s = 0.3, p = 0.04) and Thal (r_s = 0.35, p = 0.02). However, in infants with moderate-severe brain injury, a very strong correlation exists between serum lactate and cerebral lactate concentration at the BG (r_s = 0.7, p = 0.03), Thal (r_s = 0.9 p = 0.001), and GM (r_s = 0.6, p = 0.04) regions.

Conclusion

Cerebral lactate is most significantly different between regions and severity of injury during TH. There is a moderate correlation between serum and cerebral lactate concentration measured in the deep gray nuclei during TH. Differences in injury and altered regional cerebral metabolism may account for these differences.

Early Detection of Hypothermic Neuroprotection Using T2-Weighted Magnetic Resonance Imaging in a Mouse Model of Hypoxic Ischemic Encephalopathy

Perinatal hypoxic-ischemic encephalopathy (HIE) can lead to neurodevelopmental disorders, including cerebral palsy. Standard care for neonatal HIE includes therapeutic hypothermia, which provides partial neuroprotection; magnetic resonance imaging (MRI) is often used to assess injury and predict outcome after HIE. Immature rodent models of HIE are used to evaluate mechanisms of injury and to examine the efficacy and mechanisms of neuroprotective interventions such as hypothermia. In this study, we first confirmed that, in the CD1 mouse model of perinatal HIE used for our research, MRI obtained 3 h after hypoxic ischemia (HI) could reliably assess initial brain injury and predict histopathological outcome. Mice were subjected to HI (unilateral carotid ligation followed by exposure to hypoxia) on postnatal day 7 and were imaged with T2-weighted MRI and diffusion-weighted MRI (DWI), 3 h after HI. Clearly defined regions of increased signal were comparable in T2 MRI and DWI, and we found a strong correlation between T2 MRI injury scores 3 h after HI and histopathological brain injury 7 days after HI, validating this method for evaluating initial injury in this model of HIE. The more efficient, higher resolution T2 MRI was used to score initial brain injury in subsequent studies. In mice treated with hypothermia, we found a significant reduction in T2 MRI injury scores 3 h after HI, compared to normothermic littermates. Early hypothermic neuroprotection was maintained 7 days after HI, in both T2 MRI injury scores and histopathology. In the normothermic group, T2 MRI injury scores 3 h after HI were comparable to those obtained 7 days after HI. However, in the hypothermic group, brain injury was significantly less 7 days after HI than at 3 h. Thus, early neuroprotective effects of hypothermia were enhanced by 7 days, which may reflect the additional 3 h of hypothermia after imaging or effects on later mechanisms of injury, such as delayed cell death and inflammation. Our results demonstrate that hypothermia has early neuroprotective effects in this model. These findings suggest that hypothermia has an impact on early mechanisms of excitotoxic injury and support initiation of hypothermic intervention as soon as possible after diagnosis of HIE.

Prediction of outcome in asphyxiated newborns treated with hypothermia: Is a MRI scoring system described before the cooling era still useful?

AIM

To determine whether an MRI scoring system, which was validated in the pre-cooling era, can still predict the neurodevelopmental outcome of asphyxiated newborns treated with hypothermia at 2 years of age.

PATIENTS AND METHOD

We conducted a retrospective cohort study of asphyxiated newborns treated with hypothermia. An MRI scoring system, which was validated in the pre-cooling era, was used to grade the severity of brain injury on the neonatal brain MRI. Their neurodevelopment was assessed around 2 years of age; adverse outcome included cerebral palsy, global developmental delay, and/or epilepsy.

RESULTS

One hundred and sixty-nine newborns were included. Among the 131 newborns who survived and had a brain MRI during the neonatal period, 92% were evaluated around 2 years of age or later. Of these newborns, 37% displayed brain injury, and 23% developed an adverse outcome. Asphyxiated newborns treated with hypothermia who had an adverse outcome had a significantly higher MRI score (p <0.001) compared to those without an adverse outcome.

CONCLUSION

An MRI scoring system that was validated before the cooling era is still able to reliably differentiate which of the asphyxiated newborns treated with hypothermia were more prone to develop an adverse outcome around 2 years of age.

Brain Temperature Is Increased During the First Days of Life in Asphyxiated Newborns: Developing Brain Injury Despite Hypothermia Treatment

BACKGROUND AND PURPOSE

Therapeutic hypothermia is the current treatment for neonates with hypoxic-ischemic encephalopathy. It is believed to work by decreasing the brain temperature and reducing the baseline metabolism and energy demand of the brain. This study aimed to noninvasively assess brain temperature during the first month of life in neonates with hypoxic-ischemic encephalopathy treated with hypothermia.

MATERIALS AND METHODS

Neonates with hypoxic-ischemic encephalopathy treated with hypothermia and healthy neonates were enrolled prospectively. MR imaging was used to identify the presence and extent of brain injury. MR imaging multivoxel spectroscopy was used to derive brain temperatures in the basal ganglia and white matter at different time points during the first month of life. Brain temperature measurements were compared between neonates with hypoxic-ischemic encephalopathy and healthy neonates.

RESULTS

Forty-three term neonates with hypoxic-ischemic encephalopathy treated with hypothermia had a total of 74 spectroscopy scans, and 3 healthy term neonates had a total of 9 spectroscopy scans during the first month of life. Brain temperatures were lower in neonates with hypoxic-ischemic encephalopathy during hypothermia, compared with the healthy neonates (respectively, on day 1 of life: basal ganglia, 38.81°C ± 2.08°C, and white matter, 39.11°C ± 1.99°C; and on days 2-3 of life: basal ganglia, 38.25°C ± 0.91°C, and white matter, 38.54°C ± 2.79°C). However, neonates with hypoxic-ischemic encephalopathy who developed brain injury had higher brain temperatures during hypothermia (respectively, on day 1 of life: basal ganglia, 35.55°C ± 1.31°C, and white matter, 37.35°C ± 2.55°C; and on days 2-3 of life: basal ganglia, 35.20°C ± 1.15°C, and white matter, 35.44°C ± 1.90°C) compared with neonates who did not develop brain injury (respectively, on day 1 of life: basal ganglia, 34.46°C ± 1.09°C, and white matter, 33.97°C ± 1.42°C; and on days 2-3 of life: basal ganglia, 33.90°C ± 1.34°C, and white matter, 33.07°C ± 1.71°C). Also, brain temperatures tended to remain slightly higher in the neonates who developed brain injury around day 10 of life and around 1 month of age.

CONCLUSIONS

Therapeutic hypothermia using current guidelines decreased the brain temperature of neonates with hypoxic-ischemic encephalopathy during the first days of life but did not prevent an early increase of brain temperature in neonates with hypoxic-ischemic encephalopathy who developed brain injury despite this treatment.

Early Imaging and Adverse Neurodevelopmental Outcome in Asphyxiated Newborns Treated With Hypothermia

BACKGROUND

Brain injury can be identified as early as day two of life in asphyxiated newborns treated with hypothermia, when using diffusion magnetic resonance imaging (MRI). However, it remains unclear whether these diffusion changes can predict future neurodevelopment. This study aimed to determine whether abnormal early diffusion changes in newborns treated with hypothermia are associated with adverse neurodevelopmental outcome at age two years.

METHODS

Asphyxiated newborns treated with hypothermia were enrolled prospectively. They underwent magnetic resonance imaging (MRI) at specific time points over the first month of life, including diffusion-weighted imaging and diffusion-tensor imaging. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured in different regions of interest. Adverse neurodevelopmental outcome was defined as cerebral palsy, global developmental delay, and/or seizure disorder around age two years. ADC and FA values were compared between the newborns developing or not developing adverse outcome.

RESULTS

Twenty-nine asphyxiated newborns treated with hypothermia were included. Among the newborns developing adverse outcome, ADC values were significantly decreased on days two to three of life and increased around day ten of life in the thalamus, posterior limb of the internal capsule, and the lentiform nucleus. FA values decreased in the same regions around day 30 of life. These newborns also had increased ADC around day ten of life and around day 30 of life, and decreased FA around day 30 of life in the anterior and posterior white matter.

CONCLUSIONS

Diffusion changes that were evident as early as day two of life, when the asphyxiated newborns were still treated with hypothermia, were associated with later abnormal neurodevelopmental outcome.

MRI and spectroscopy in (near) term neonates with perinatal asphyxia and therapeutic hypothermia

BACKGROUND

Previous studies have demonstrated the association of abnormalities on diffusion-weighted MRI (DW-MRI) and proton magnetic resonance spectroscopy (¹H-MRS) in infants with perinatal asphyxia. The use of therapeutic hypothermia might change this association.

AIM

To study the association between DW-MRI and ¹H-MRS and outcome after perinatal asphyxia and therapeutic hypothermia in infants with a gestational age of ≥36 weeks.

PATIENTS AND METHODS

Infants with perinatal asphyxia and therapeutic hypothermia (n=88) were included when an MR examination was performed within 7 days after birth. Apparent diffusion coefficient (ADC) values of the basal ganglia and thalamus were calculated, as were lactate/N-acetylaspartate (LAC/NAA) and N-acetylaspartate/choline (NAA/Cho) ratios. Death or an abnormal neurodevelopment at ≥24 months was considered an adverse outcome. Receiver operating characteristic analysis was performed to determine cut-off levels.

RESULTS

Of the 88 infants, 22 died and 7 had an adverse neurodevelopmental outcome. In infants with an adverse outcome, ADC values of the basal ganglia and thalamus were significantly lower, and Lac/NAA ratios were significantly higher than in infants with a normal outcome. Areas under the curve of ADC of the basal ganglia, thalami and Lac/NAA ratio were 0.89, 0.88 and 0.87, respectively. NAA/Cho ratios were in this cohort not associated with outcome.

CONCLUSIONS

During and after therapeutic hypothermia, low ADC values and high Lac/NAA ratios of the basal ganglia and thalamus are associated with an adverse outcome in infants with perinatal asphyxia.

Comparison of early and late MRI in neonatal hypoxic-ischemic encephalopathy using three assessment methods

BACKGROUND

There is no consensus on the optimum timing of MRI in neonates with hypoxic-ischemic encephalopathy treated with hypothermia. Reliable early imaging assessment might help managing treatment.

OBJECTIVE

To assess non-random differences between early and late MRI that might influence intensive-care decisions.

MATERIALS AND METHODS

This single-center retrospective study included all asphyxiated term neonates eligible for hypothermia treatment November 2009-July 2012. MRI scans were systematically performed at day 4 (early MRI) and day 11 of life as part of routine protocol. Two experienced pediatric radiologists reviewed both scans according to three assessment methods: a pattern classification, a scoring system and a simplified classification. Agreement between early and late imaging findings was assessed using Cohen's kappa coefficients.

RESULTS

Thirty-three neonates were included. Interobserver agreement was excellent. Early MRI detected all severe injuries. Agreement between early and late MRI was excellent for the simplified classification (κ = 0.82), good for the pattern classification (κ = 0.64), and good to excellent for 3 scores out of 4 in the scoring system (κ = 0.70-0.89).

CONCLUSION

Early MRI may provide valuable information about brain injury to help parents and neonatologists in intensive-care decisions at the end of hypothermia treatment.

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.

Somatosensory evoked potentials in neonates with hypoxic-ischemic encephalopathy treated with hypothermia

OBJECTIVE

Somatosensory evoked potentials (SEPs) are reported to have high positive predictive value (PPV) for neurodevelopmental impairment (NDI) in neonates with moderate or severe hypoxic-ischemic encephalopathy (HIE). Our objective was to assess if this predictive value remains high with the use of therapeutic hypothermia.

METHODS

A cohort of HIE neonates treated with hypothermia was recruited between September 2008 and September 2010. SEPs were elicited after hypothermia and classified as bilateral absent N19, abnormal N19 (i.e., delayed or unilateral absent), or normal. Qualitative evaluation of MRI was also performed. The primary outcome was moderate or severe NDI around 2 years of age.

RESULTS

SEPs were performed after hypothermia in 26 of 34 neonates submitted to hypothermia with adequate follow-up at a median day of life 11 (IQR 9, 13). Twenty-three (88%) had moderate encephalopathy. Eleven neonates (42%) had bilateral absent N19, 4 of whom had NDI, while fifteen neonates (58%) had either abnormal or normal N19, of whom only one had NDI. SEPs thus had a PPV of 0.36 (4/11) and a negative predictive value (NPV) of 0.93 (14/15). Eighteen neonates (69%) had brain injury on MRI. MRI thus had a PPV of 0.28 (5/18) and an NPV of 1.00 (8/8).

CONCLUSIONS

Neonates with HIE treated with hypothermia with bilateral absent N19 potentials may have a better prognosis than reported in the pre-hypothermia era. MRI also had a low PPV and high NPV. SEPs should be interpreted with caution in this new population and need to be re-evaluated in larger studies.

Angiogenesis dysregulation in term asphyxiated newborns treated with hypothermia

BACKGROUND

Neonatal encephalopathy following birth asphyxia is a major predictor of long-term neurological impairment. Therapeutic hypothermia is currently the standard of care to prevent brain injury in asphyxiated newborns but is not protective in all cases. More robust and versatile treatment options are needed. Angiogenesis is a demonstrated therapeutic target in adult stroke. However, no systematic study examines the expression of angiogenesis-related markers following birth asphyxia in human newborns.

OBJECTIVE

This study aimed to evaluate the expression of angiogenesis-related protein markers in asphyxiated newborns developing and not developing brain injury compared to healthy control newborns.

DESIGN/METHODS

Twelve asphyxiated newborns treated with hypothermia were prospectively enrolled; six developed eventual brain injury and six did not. Four healthy control newborns were also included. We used Rules-Based Medicine multi-analyte profiling and protein array technologies to study the plasma concentration of 49 angiogenesis-related proteins. Mean protein concentrations were compared between each group of newborns.

RESULTS

Compared to healthy newborns, asphyxiated newborns not developing brain injury showed up-regulation of pro-angiogenic proteins, including fatty acid binding protein-4, glucose-6-phosphate isomerase, neuropilin-1, and receptor tyrosine-protein kinase erbB-3; this up-regulation was not evident in asphyxiated newborns eventually developing brain injury. Also, asphyxiated newborns developing brain injury showed a decreased expression of anti-angiogenic proteins, including insulin-growth factor binding proteins -1, -4, and -6, compared to healthy newborns.

CONCLUSIONS

These findings suggest that angiogenesis pathways are dysregulated following birth asphyxia and are putatively involved in brain injury pathology and recovery.