Anatomic changes and imaging in assessing brain injury in the term infant

Differences between early and late MRI in infants with neonatal encephalopathy following therapeutic hypothermia

BACKGROUND

MRI is the gold standard test to define brain injury in infants with neonatal encephalopathy(NE). As imaging findings evolve considerably over the first week, early imaging may not fully reflect the final nature of the injury. This study aimed to compare day 4 versus second week MRI in infants with NE.

METHODS

Retrospective cohort study including infants who received therapeutic hypothermia(TH) for NE and had two MRIs: early (≤7days) and late (>7days). MRIs were clinically reported and also reviewed by study investigators.

RESULTS

94infants with NE were included (40mild,49moderate,5severe). Twenty-four infants(26%) had a normal early scan of which 3/24(13%) had injury noted on repeat MRI. Seventy infants(74%) had abnormal findings noted on early MRI, of which 4/70(6%) had further evolution of injury while 11/70(16%) had complete resolution of findings. Applying a grading system resulted in a change of grade in 7 infants.

CONCLUSION

In infants who received TH for NE, 19% had changes noted between their early and late MRIs. While the impact on predicting neurodevelopmental outcome was not studied, relying solely on early MRI may overestimate injury in a proportion of infants and miss injury in others. Combining early and late MRI allows for better characterization of injury.

IMPACT

MRI is the gold standard tool to define brain injury in infants with NE, however, imaging findings evolve considerably over the first week of life. Most centers perform a single MRI on day 4 after rewarming. In our cohort, 19% of infants had a notable change in their MRI findings between early (within the first week) and late (beyond the first week) scans. Relying solely on early MRI may overestimate injury in a proportion of infants and miss injury in others. Combining early and late MRI following hypothermia allows for better characterization of brain injury.

Blood Plasma Metabolic Profile of Newborns with Hypoxic-Ischaemic Encephalopathy by GC-MS

Background

Early diagnosis of hypoxic-ischaemic encephalopathy (HIE) is crucial in preventing neurodevelopmental disabilities and reducing morbidity and mortality. The study was to investigate the plasma metabolic signatures in the peripheral blood of HIE newborns and explore the potential diagnostic biomarkers.

Method

In the present study, 24 newborns with HIE and 24 healthy controls were recruited. The plasma metabolites were measured by gas chromatography-mass spectrometry (GC-MS), and the raw data was standardized by the EigenMS method. Significantly differential metabolites were identified by multivariate statistics. Pathway enrichment was performed by bioinformatics analysis. Meanwhile, the diagnostic value of candidate biomarkers was evaluated.

Result

The multivariate statistical models showed a robust capacity to distinguish the HIE cases from the controls. 52 metabolites were completely annotated. 331 significantly changed pathways were enriched based on seven databases, including 33 overlapped pathways. Most of them were related to amino acid metabolism, energy metabolism, neurotransmitter biosynthesis, pyrimidine metabolism, the regulation of HIF by oxygen, and GPCR downstream signaling. 14 candidate metabolites showed great diagnostic potential on HIE. Among them, alpha-ketoglutaric acid has the potential to assess the severity of HIE in particular.

Conclusion

The blood plasma metabolic profile could comprehensively reflect the metabolic disorders of the whole body under hypoxia-ischaemic injury. Several candidate metabolites may serve as promising biomarkers for the early diagnosis of HIE. Further validation based on large clinical samples and the establishment of guidelines for the clinical application of mass spectrometry data standardization methods are imperative in the future.

Hearing Impairment in Infants with Hypoxic Ischemic Encephalopathy Treated with Hypothermia

Therapeutic hypothermia acts as the standard of care for infants with moderate to severe hypoxic ischemic encephalopathy (HIE). A proportion of neonates who undergo hypothermia due to HIE have shown to develop various degrees of hearing impairment. Analyzing and identifying infants at high risk of developing hearing difficulties is fundamental for early intervention of such auditory complications. The aim was to assess clinical factors in the development of hearing impairment following therapeutic hypothermia in HIE infants. A retrospective analysis was performed on infants hospitalized in our neonatology department in Poznan University of Medical Sciences, Poland. All infants experienced moderate to severe HIE, and were treated with therapeutic hypothermia. Risk factors for hearing impairment were identified in all infants included in the study. Clinical data during hospital stay and follow-up hearing status were analyzed. A total of 87 HIE infants were included in the study. Seventy-six infants (40 male and 36 female) had otoacoustic emission (OAE) examination following birth, of which 14 (18.4%) demonstrated abnormal (positive) results. Infants with abnormal OAE results had significantly lower blood pH (6.86 ± 0.16, p = 0.001) and base excess (BE) (-22.46 ± 2.59, p = 0.006). Of the 49 infants who returned for follow-up assessment, 4 (8.2%) were diagnosed with sensorineural bilateral hearing impairment (1 infant, mild [<40 dB], 2 moderate [41-70 dB], and 1 profound [>90 dB]). The biochemical analysis following birth revealed significantly lower umbilical BE levels (-23.90 ± 4.99, p = 0.041) and higher lactate levels (160.67 ± 4.93, p = 0.019) in the infants with eventual sensorineural hearing deficit. Infants with moderate or severe HIE are at risk of delayed onset hearing loss. Diligent efforts to monitor auditory status are required, even if early screening results for hearing are insignificant. Exploring biochemical parameters, such as lactate, BE, and blood pH, can prove beneficial in identifying HIE infants at risk of developing a hearing impairment.

Beyond Anesthesia Toxicity: Anesthetic Considerations to Lessen the Risk of Neonatal Neurological Injury

Infants who undergo surgical procedures in the first few months of life are at a higher risk of death or subsequent neurodevelopmental abnormalities. Although the pathogenesis of these outcomes is multifactorial, an understanding of the nature and pathogenesis of brain injury in these infants may assist the anesthesiologist in consideration of their day-to-day practice to minimize such risks. This review will summarize the main types of brain injury in preterm and term infants and their key pathways. In addition, the review will address key potential pathogenic pathways that may be modifiable including intraoperative hypotension, hypocapnia, hyperoxia or hypoxia, hypoglycemia, and hyperthermia. Each of these conditions may increase the risk of perioperative neurological injury, but their long-term ramifications are unclear.

Maternal pomegranate juice intake and brain structure and function in infants with intrauterine growth restriction: A randomized controlled pilot study

Polyphenol-rich pomegranate juice has been shown to have benefit as a neuroprotectant in animal models of neonatal hypoxic-ischemia. No published studies have investigated maternal polyphenol administration as a potential neuroprotectant in at-risk newborns, such as those with intrauterine growth restriction (IUGR). This was a randomized, placebo-controlled, double-blind pilot study to investigate the impact of maternal pomegranate juice intake in pregnancies with IUGR, on newborn brain structure and function at term-equivalent age (TEA). Mothers with IUGR at 24-34 weeks' gestation were recruited from Barnes-Jewish Hospital obstetrical clinic. Consented mothers were randomized to treatment (8 oz. pomegranate juice) or placebo (8 oz. polyphenol-free juice) and continued to take juice daily from enrollment until delivery (mean 20.1 and 27.1 days, respectively). Infants underwent brain MRI at TEA (36-41 weeks' gestation). Brain measures were compared between groups including: brain injury score, brain metrics, brain volumes, diffusion tensor imaging and resting state functional connectivity. Statistical analyses were undertaken as modified intention-to-treat (including randomized participants who received their allocated intervention and whose infants received brain MRI) and per-protocol (including participants who strictly adhered to the protocol, based on metabolite status). Seventy-seven mothers were randomized to treatment (n = 40) or placebo (n = 37). Of these, 28 and 27 infants, respectively, underwent term-equivalent MRI. There were no group differences in brain injury, metrics or volumes. However, treatment subjects displayed reduced diffusivity within the anterior and posterior limbs of the internal capsule compared with placebo. Resting state functional connectivity demonstrated increased correlation and covariance within several networks in treatment subjects, with alterations most apparent in the visual network in per-protocol analyses. Direct effects on health were not found. In conclusion, maternal pomegranate juice intake in pregnancies with known IUGR was associated with altered white matter organization and functional connectivity in the infant brain, suggesting differences in brain structure and function following in utero pomegranate juice exposure, warranting continued investigation. Clinical trial registration. NCT00788866, registered November 11, 2008, initial participant enrollment August 21, 2012.

Early Prediction of Hypoxic-Ischemic Brain Injury by a New Panel of Biomarkers in a Population of Term Newborns

This research paper is aimed at evaluating the predictive role of a default panel of oxidative stress (OS) biomarkers for the early identification of infants at high risk of HIE and their validation through the correlation with MRI findings. A multicenter prospective observational study was performed between March 2012 and April 2015 in two European tertiary NICUs. Eighty-four term infants at risk for HIE (pH < 7, BE < −13 mmol/L, and 5′ Apgar < 5) were enrolled. Three were excluded for chromosomal abnormalities and one due to lack of blood samples. The final population was divided according to the severity of perinatal hypoxia into 2 groups: mild/moderate HIE and severe HIE. Advanced oxidation protein products (AOPP), non-protein-bound iron (NPBI), and F2-isoprostanes (F2-IsoPs) were measured in blood samples at P1 (4–6 hours), P2 (24–72 hours), and P3 (5 days), in both groups. MRIs were scored for the severity of brain injury, using a modified Barkovich score. The mean GA was 39.8 weeks (SD 1.4) and the mean birth weight 3538 grams (SD 660); 37 were females and 43 males. Significantly lower 5′ Apgar score, pH, and BE and higher Thompson score were found in group II compared to group I at birth. Group II showed significantly higher AOPP and NPBI levels than group I (mean (SD) AOPP: 15.7 (15.5) versus 34.1 (39.2), p = 0.033; NPBI 1.1 (2.5) versus 3.9 (4.4), p = 0.013) soon after birth (P1). No differences were observed in OS biomarker levels between the two groups at P2 and P3. A regression model, including adjustment for hypothermia treatment, gender, and time after birth, showed that AOPP levels and male gender were both risk factors for higher brain damage scores (AOPP: OR 3.6, 95% CI (1.1–12.2) and gender: OR 5.6, 95% CI (1.2–25.7), resp.). Newborns with severe asphyxia showed higher OS than those with mild asphyxia at birth. AOPP are significantly associated with the severity of brain injury assessed by MRI, especially in males.

Magnetization transfer and diffusion imaging of acute axonal damage in the cerebral peduncle following hypoxia-ischemia in neonatal rats

BACKGROUND

Magnetic resonance imaging (MRI) of axonal degenerative changes in the cerebral peduncle of the corticospinal tract following cerebral hypoxic-ischemic damage might distinguish infants most appropriate for receiving prompt treatment. The optimal MRI sequence for very early diagnosis of axonal degenerative changes is unknown. We hypothesized that magnetization transfer ratio (MTR) imaging would be more sensitive than traditional MRI, e.g., T(2) or diffusion weighted imaging.

METHODS

Transient unilateral cerebral hypoxia-ischemia was produced in the neonatal rat followed by MRI of changes in T(2), the apparent diffusion coefficient (ADC) of water, and MTR, with a focus on the parietal cortex (an ischemic damaged region) and the cerebral peduncle (remote within the corticospinal tract). Rats were imaged at 2 h, 1 d, or 1 wk postinsult.

RESULTS

In the cerebral peduncle, MTR and T(2) responded similarly, with alterations occurring ipsilaterally at 1 d postinsult. ADC was most sensitive for detecting changes as early as 2 h postinsult, and this corresponded to a reduced staining of axonal filaments ipsilaterally.

CONCLUSION

MTR and T(2) imaging have comparable sensitivity for distinguishing early axonal damage in the cerebral peduncle. ADC imaging is highly sensitive for detecting early disruption of corticospinal axons, supporting its potential hyperacute diagnostic use clinically.

Potential application of hydrogen in traumatic and surgical brain injury, stroke and neonatal hypoxia-ischemia

This article summarized findings of current preclinical studies that implemented hydrogen administration, either in the gas or liquid form, as treatment application for neurological disorders including traumatic brain injury (TBI), surgically induced brain injury (SBI), stroke, and neonatal hypoxic-ischemic brain insult (HI). Most reviewed studies demonstrated neuroprotective effects of hydrogen administration. Even though anti-oxidative potentials have been reported in several studies, further neuroprotective mechanisms of hydrogen therapy remain to be elucidated. Hydrogen may serve as an adjunct treatment for neurological disorders.

Ultrasound detection of posterior fossa abnormalities in full-term neonates

Routine cranial ultrasonography, using the anterior fontanelle as acoustic window enables visualization of the supratentorial brain structures in neonates and young infants. The mastoid fontanelle enables a better view of the infratentorial structures, especially cerebellar hemorrhage in preterm infants. Reports on the usefulness and reliability of cranial ultrasonography using the mastoid fontanelle approach for the detection of posterior fossa abnormalities, focusing only on full-term neonates are limited. This article describes the technique of mastoid fontanelle ultrasonography in full-term neonates and the features of posterior fossa abnormalities that may be encountered in various neonatal disorders and conditions, combined with subsequent MRI in the same patients. Cranial ultrasound through the mastoid fontanelle plays a pivotal role in the early detection of posterior fossa pathology and selection of neonates with an indication for MRI.

An interdisciplinary fetal/neonatal neurology program

A fetal/neonatal neurology program should encompass interdisciplinary service, educational and research objectives, merging curricula concerning maternal, placental, fetal and neonatal contributions to brain health and disease. This approach is anchored by research in early life programming that demonstrates that prenatal and postnatal factors influence long-term neurologic health. This concept also supports the design of neuroprotective interventions during critical periods of brain development when brain circuitries more optimally adapt to maturational challenges. Preventive, rescue and repair protocols will transform pediatric medical practices, to promote improved childhood outcomes. Inclusion of life-course science and research will identify medical and socioeconomic factors that favorably or adversely affect quality of life into adulthood. Greater awareness of the convergence of developmental origins of brain health and disease and developmental aging theories will influence public health policies, to encourage financial support for programs that will improve the quality of life for the child and adult.

Magnetic resonance imaging studies without sedation in the neonatal intensive care unit: safe and efficient

Use of magnetic resonance imaging (MRI) in the neonatal intensive care unit has been increasing over the past several years because of improved MRI technology and increased clinical awareness of the prognostic and diagnostic information available. Historically, the use of sedation has been the standard for achieving quality imaging without motion artifact, but it exposed the patient to risks associated with sedation medications. In an effort to obtain MRI studies with elimination of risks associated with sedation, a quality improvement project was initiated. Implementing a standardized approach utilizing a vacuum immobilizer has led to successful neonatal MRI completion without the need for sedation in 94% of study attempts. Acceptable or excellent image quality was achieved in more than 97% of attempts. Time away from the neonatal intensive care unit significantly decreased with this approach, with the mean duration of time away decreasing from 60 to 48 minutes (P < .0001). Obtaining MRI studies without sedation can be successfully implemented in a neonatal intensive care unit, nearly eliminating patient risks associated with sedation while improving utilization of hospital resources and maintaining adequate quality imaging.

Survival in acute and severe low o environment: use of a genetic model system

Hypoxia whether present during physiologic states (e.g., embryogenesis) or during pathologic states (e.g., obstructive sleep apnea and sickle cell anemia), challenges the vertebrate or invertebrate organism. Clearly, hypoxia can lead to sublethal cell injury or death and consequently organ or systemic injury and failure, depending on severity. We discovered that the adult Drosophila melanogaster is tolerant to a low O(2) environment, withstanding approximately 3-4 hours of total O(2) deprivation or anoxia without showing any evidence of cell injury. This opened major avenues for us since the Drosophila has been used so effectively in so many relevant research areas. We investigated the changes in gene expression in D. melanogaster after severe (1% O(2)) intermittent or constant hypoxia treatment for 2.5 hours. Our microarray analysis has identified multiple gene families that are up- or downregulated in response to acute constant (CH) and intermittent hypoxia (IH). We observed that even for short-term the gene expression response to IH and CH varied not only in the number of genes but also type of gene families. Furthermore, by utilizing powerful Drosophila genetic tools we studied the role of single genes (up- or downregulated in arrays) in survival under either paradigm in adult flies. We observed significant increased adult survival (as compared to controls) of P-element lines for Hsp70 and Hsp23 genes during CH and Mdr49 and l (2)08717 genes during IH. This suggests that the increased transcript levels as observed in array data after either paradigm play an important role under severe hypoxia. Indeed, we found for example that over-expressing Hsp70 in vivo in specific fly organs (such as heart) significantly increased adult survival during CH as compared to controls. These data provide further clues about the mechanisms by which intermittent and constant hypoxia lead to cell injury and morbidity or adaptation and survival.