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An-Massaro

Keeping an eye on autonomic function for infants with HIE

An-Massaro

“By including heart rate variability measurements and other markers of autonomic function in our current predictive armamentarium,” says An Massaro, M.D., “we may be able to offer new hope for infants with HIE.”

In about two to three in every 1,000 full-term births, babies develop a neurological condition called hypoxic ischemic encephalopathy (HIE) when their brains receive insufficient oxygen. HIE can be a devastating condition, leading to severe developmental or cognitive delays or motor impairments that become more evident as the child grows older. Despite improvements in care – including therapeutic hypothermia, a whole-body cooling method administered shortly after birth that can slow brain damage – about half of children with this condition die from neurological complications by age 2.

Finding ways to identify children with the most severe HIE could help researchers focus their efforts and provide even more intense neuroprotective care, explains An Massaro, M.D., a neonatologist at Children’s National Health System. But thus far, it’s been unclear which symptoms reflect the extent of HIE-induced brain damage.

That’s why Dr. Massaro and colleagues embarked on a study published in the May 2018 issue of Journal of Pediatrics. The team sought to determine whether dysfunction of the autonomic nervous system (ANS) – the auto-pilot part of the nervous system responsible for unconscious bodily functions, such as breathing and digestion – reflected in routine care events can be used as a marker for brain injury severity.

The researchers collected data from 25 infants who were treated for HIE with therapeutic hypothermia at Children’s National. Thanks to multi-modal monitoring, these babies’ medical records hold a treasure trove of information, explains Rathinaswamy B. Govindan, Ph.D., a staff scientist in Children’s Advanced Physiological Signals Processing Lab.

In addition to including continuous heart rate tracings and blood pressure readings that are standard for many infants in the neonatal intensive care unit (NICU), they also recorded cerebral near infrared spectroscopy, a monitor that measures brain tissue oxygen levels. The investigators performed detailed analyses to evaluate how these monitor readings change in response to a variety of routine care events, such as diaper changes, heel sticks, endotracheal tube manipulations and pupil examinations.

The researchers stratified these infants based on how dysfunctional their ANS behaved by using heart rate variability as a marker: The fewer natural fluctuations in heart rate, the more damaged their ANS was thought to be. And they also used non-invasive brain magnetic resonance imaging (MRI) to determine brain damage. They then compared this information with the babies’ physiological responses during each care event.

Their findings show that infants with impaired ANS, based on depressed heart rate variability before the care event, had significantly different responses to these care events compared with babies with intact ANS.

  • For stimulating interventions, such as diaper changes and heel sticks, both heart rate and blood pressure increased in babies with intact ANS but decreased in babies with impaired ones.
  • Shining a light in their pupils led to an expected decreased heart rate with stable blood pressure in ANS-intact infants, but in ANS-impaired infants, there was no responsive change in heart rate and, additionally, a decrease in blood pressure was observed.
  • Responses were similar between the two groups during breathing tube manipulations, except for a slight increase in heart rate a few minutes later in the ANS-impaired group.

These results, Govindan explains, suggest that a real-time, continuous way to assess ANS function may offer insights into the expected physiological response for a given infant during routine NICU care.

“This is exactly the type of additional information that intensivists need to pinpoint infants who may benefit from additional neuroprotective support,” he says. “Right now, it is standard practice to monitor brain activity continuously using electroencephalogram and to check the status of the brain using MRI to assess the response to therapeutic cooling. Neither of these assessments can be readily used by neonatologists at the bedside in real-time to make clinical decisions.”

Assessing ANS function in real-time can help guide neuroprotective care in high-risk newborns by providing insight into the evolving nature of brain damage in these infants, Dr. Massaro adds.

Beyond simply serving as a biomarker into brain injury, poor ANS function also could contribute to the development of secondary injury in newborns with HIE by stymieing the normal changes in heart rate and blood pressure that help oxygenate and heal injured brains. The researchers found that the cumulative duration of autonomic impairment was significantly correlated with the severity of brain injury visible by MRI in this group of infants.

“By including heart rate variability measurements and other markers of autonomic function in our current predictive armamentarium,” says Dr. Massaro, “we may be able to offer new hope for infants with HIE.”

In addition to Dr. Massaro, the Senior Author, study co-authors include Lead Author, Heather Campbell, M.D.; Rathinaswamy B. Govindan, Ph.D., Children’s Advanced Physiological Signals Processing Lab; Srinivas Kota, Ph.D.; Tareq Al-Shargabi, M.S.; Marina Metzler, B.S.; Nickie Andescavage, M.D., Children’s neonatalogist; Taeun Chang, M.D., Children’s neonatal and fetal neurologist; L. Gilbert Vezina, M.D., attending in Children’s Division of Diagnostic Imaging and Radiology; and Adré J. du Plessis, M.B.Ch.B., M.P.H., chief of Children’s Division of Fetal and Transitional Medicine.

This research was supported by the Clinical and Translational Science Institute at Children’s National under awards UL1TR000075 and 1KL2RR031987-01 and the Intellectual and Developmental Disabilities Research Consortium within the National Institutes of Health under award P30HD040677.

Sarah Mulkey

MRI finds novel brain defects in Zika-exposed newborns

Sarah Mulkey

“Imaging is constantly helping us make new discoveries with this virus, and in these two cases we found things that had not been previously described,” says Sarah Mulkey, M.D., Ph.D.

Magnetic resonance imaging (MRI) has identified two brain abnormalities never before reported in newborns with prenatal exposure to the Zika virus. Children’s National Health System researchers reported these findings from a study of more than 70 fetuses or newborns with Zika exposure in utero. The study was published in the January 2018 edition of Pediatric Neurology.

The two novel defects – cranial nerve enhancement and cerebral infarction – may join the growing list of neurological findings associated with congenital Zika infection.

“Imaging is constantly helping us make new discoveries with this virus, and in these two cases we found things that had not been previously described,” says Sarah Mulkey, M.D., Ph.D., the study’s lead author and a fetal-neonatal neurologist at Children’s National. Dr. Mulkey works in Children’s Congenital Zika Virus Program, one of the nation’s first comprehensive, dedicated Zika programs.

The research team recommends that postnatal brain MRI be considered in addition to ultrasound for newborns exposed to Zika in utero. “Brain MRI can be performed in the newborn often without sedation and provides an opportunity to look for brain abnormalities we might not catch otherwise – or might not detect until much later,” says Dr. Mulkey.

Birth defects are seen in 6 to 11 percent of pregnancies affected by Zika, and some of the neurological complications in infants are not apparent until well after birth.

Of the two infants in which the new abnormalities were observed, both had normal head size at birth. Neither had smaller-than-normal head size (microcephaly), one of the more severe effects associated with congenital Zika syndrome.

One infant had a normal neurological evaluation at 2 days of age. However, a brain MRI conducted the following day, using gadolinium contrast due to concern of infection, showed enhancement of multiple cranial nerves. “Nerve root enhancement is very rare in a newborn and had not been described with Zika before,” Dr. Mulkey says. “Yet, there was no neurological deficit that we could identify by physical exam.”

The research team acknowledges that the clinical significance of this finding is not yet known.

In the second patient, brain MRI conducted without contrast at 16 days of age revealed a small area consistent with chronic infarction (ischemic stroke) that likely occurred during the third trimester.

“We followed the mother throughout her pregnancy, and both MRI and ultrasound imaging were normal at 28 weeks gestation,” Dr. Mulkey says. “A postnatal ultrasound was also normal, but the postnatal MRI showed a stroke that had occurred at least one month prior to the MRI and after the last fetal study.”

She adds: “This is the first published report of fetal stroke associated with Zika infection, and it may add to our knowledge of what can occur with congenital Zika infection.”

Unlike most congenital infections, Zika virus does not appear to cause viral-induced placental inflammation, which can lead to fetal stroke. So, the authors say they cannot be sure that congenital Zika contributed to the infarct in this case. However, they write, “Given the relatively low incidence of perinatal ischemic infarct and the lack of other maternal- or birth-related risk factors for this patient, Zika infection is considered a possible etiology.”

In both patients, neonatal brain MRI identified subclinical findings that had not previously been described as part of congenital Zika syndrome. As the body of evidence about the Zika virus has grown, the spectrum of associated brain abnormalities has expanded to include considerably more findings than isolated microcephaly.

Data gathered in 2017 from the Centers for Disease Control and Prevention’s Zika pregnancy and infant registry indicates that 25 percent of eligible U.S. infants receive recommended postnatal imaging. Dr. Mulkey said this represents many possible missed opportunities for earlier identification of brain abnormalities.

“Brain MRI should be considered in all newborns exposed to Zika virus in utero, even in the presence of normal birth head circumference, normal cranial ultrasound and normal fetal imaging,” she says. “In both of these patients, the changes we observed were not evident on cranial ultrasound or on fetal MRI and fetal ultrasound.”

In addition to Dr. Mulkey, Children’s co-authors include L. Gilbert Vezina, M.D., Neuroradiology Program director; Dorothy I. Bulas, M.D., chief of Diagnostic Imaging and Radiology; Zarir Khademian, M.D., radiologist; Anna Blask, M.D., radiologist; Youssef A. Kousa, M.S., D.O., Ph.D., child neurology fellow; Lindsay Pesacreta, FNP; Adré  J. du Plessis, M.B.Ch.B., M.P.H., Fetal Medicine Institute director; and Roberta L. DeBiasi, M.D., M.S., senior author and Pediatric Infectious Disease division chief; and Caitlin Cristante, B.S.

Financial support for this research was provided by the Thrasher Research Fund.

Pregnant-Mom

MRI opens new understanding of fetal growth restriction

Pregnant-Mom

Quantitative MRI can identify placental dysfunction complicated by fetal growth restriction earlier, creating the possibility for earlier intervention to minimize harm to the developing fetus.

A team of researchers has found that quantitative magnetic resonance imaging (MRI) can identify pregnancies where placental dysfunction results in fetal growth restriction (FGR), creating the possibility for earlier FGR detection and intervention to augment placental function and thus minimize harm to the fetal brain.

The study, published online in the Journal of Perinatology, reports for the first time that in vivo placental volume is tied to global and regional fetal brain volumes.

Placental insufficiency is a known risk factor for impaired fetal growth and neurodevelopment. It may cause the fetus to receive inadequate oxygen and nutrients, making it difficult to grow and thrive. The earlier placental insufficiency occurs in a pregnancy, the more serious it can be. But detecting a failing placenta before the fetus is harmed has been difficult.

One additional challenge is that a fetus may be small because the placenta is not providing adequate nourishment. Or the fetus simply may be genetically predisposed to be smaller. Being able to tell the difference early can have a lifelong impact on a baby. Infants affected by FGR can experience behavioral problems, learning difficulties, memory and attention deficits, and psychiatric issues as the child grows into adolescence and adulthood.

“Our study proved that MRI can more accurately determine which pregnancies are at greater risk for impaired fetal health or compromised placenta function,” says Nickie Andescavage, M.D., the study’s lead author and a specialist in neonatology and neonatal neurology and neonatal critical care at Children’s National Health System. “The earlier we can identify these pregnancies, the more thoughtful we can be in managing care.”

Dr. Andescavage’s research focus has been how fetal growth affects labor, delivery and postnatal complications.

Nickie-Andescavage-Niforatos

“Our study proved that MRI can more accurately determine which pregnancies are at greater risk for impaired fetal health or compromised placenta function,” says Nickie Andescavage, M.D., the study’s lead author.

“We don’t have a good understanding of why FGR happens, but we do know it’s hard to identify during pregnancy because often there are no signs,” says Dr. Andescavage. “Even when detected, it’s hard to follow. But if we’re aware of it, we can better address important questions, like when to deliver an at-risk fetus.”

In the study, the team measured placental and fetal brain growth in healthy, uncomplicated pregnancies and in pregnancies complicated by FGR. A total of 114 women participated, undergoing ultrasound, Doppler ultrasound and MRI imaging to measure placental volume and fetal brain volume.

An ultrasound test is often what detects FGR, but the measurements generated by ultrasound can be non-specific. In addition, reproducibility issues with 3D sonography limit its use as a standalone tool for placental assessment. Once FGR is detected via ultrasound, this study showed that complementary MRI provides more accurate structural measures of the fetal brain, as well as more detail and insight into placental growth and function.

“Our team has studied FGR for a few years, using imaging to see that’s happening with the fetus in real time,” says Dr. Andescavage. “The relationship of placental volume and fetal brain development had not been previously studied in utero.”

In pregnancies complicated by FGR, MRI showed markedly decreased placental and brain volumes. The team observed significantly smaller placental, total brain, cerebral and cerebellar volumes in these cases than in the healthy controls. The relationship between increasing placental volume and increasing total brain volume was similar in FGR and in normal pregnancies. However, the study authors write “the overall volumes were smaller and thus shifted downward in pregnancies with FGR.”

In addition, FGR-complicated pregnancies that also showed abnormalities in Doppler ultrasound imaging had even smaller placental, cerebral and cerebellar volumes than pregnancies complicated by FGR that did not have aberrations in Doppler imaging.

Since this study showed that quantitative fetal MRI can accurately detect decreased placental and brain volumes when FGR is present, Dr. Andescavage believes this imaging technique may give doctors important new insights into the timing and possibly the mechanisms of brain injury in FGR.  “Different pathways can lead to FGR. With this assessment strategy, we could potentially elucidate those,” she adds.

Using quantitative MRI to identify early deviations from normal growth may create opportunities for future interventions to protect the developing fetal brain. New treatments on the horizon promise to address placental health. MRI could be used to investigate these potential therapies in utero. When those therapies become available, it could allow doctors to monitor treatment effects in utero.

Study co-authors include Adré J. du Plessis, M.B.Ch.B., M.P.H., Director of Children’s Fetal Medicine Institute; Marina Metzler; Dorothy Bulas, M.D., FACR, FAIUM, FSRU, Chief of Children’s Division of Diagnostic Imaging and Radiology; L. Gilbert Vezina, M.D., Director of Children’s Neuroradiology Program; Marni Jacobs; Catherine Limperopoulos, Ph.D., Director of Children’s Developing Brain Research Laboratory and study senior author; Sabah N. Iqbal, MedStar Washington Hospital Center; and Ahmet Alexander Baschat, Johns Hopkins Center for Fetal Therapy.

Research reported in this post was supported by the Canadian Institutes of Health Research, MOP-81116; the National Institutes of Health under award numbers UL1TR000075 and KL2TR000076; and the Clinical and Translational Science Institute at Children’s National.

Volumetric imaging of upper airways

Preemies’ narrowed upper airways may explain higher OSA risk

Volumetric imaging of upper airways

The airway structures of interest to the Children’s National research team included the nasopharynx (labeled red), oropharynx (labeled purple), hypopharynx (labeled green), adenoids (labeled yellow) and tonsils (labeled blue). The team displayed the volumetric imaging in three perpendicular planes and a three-dimensional model.
Credit: A. Smitthimedhin, et al, Clinical Imaging.

Infants born preterm have significantly lower nasopharyngeal and oropharyngeal volumes, compared with newborn peers carried to full term, and those lower airway volumes are independent of the infants’ gender, ethnicity or weight, according to a study published online Dec. 16, 2017 in Clinical Imaging.

According to the Centers for Disease Control and Prevention, 1 in 10 babies born in the United States is preterm, or born prior to the 37th gestational week. Premature birth leaves these children more susceptible to disordered breathing while sleeping, including obstructive sleep apnea (OSA), an ailment characterized by increased upper-airway resistance that narrows airways.

“In addition to finding some airway volumes were smaller in preterm infants, our results indicated both sets of newborns had similar hypopharyngeal volumes. This suggests that risk factors that lead to OSA are confined to the uppermost airway and do not appear to be explained by enlarged adenoids and tonsils,” says Anilawan Smitthimedhin, a Children’s National Health System radiology research fellow at the time the study was performed and lead author of the paper.

In order to diagnose OSA, clinicians now use bronchoscopy, but the method has limitations, including the need to insert a lighted instrument into the airway, which can affect pressure and resistance within the airway.

The Children’s National research team theorized that magnetic resonance imaging (MRI) could offer a non-invasive way to evaluate the upper airway, determine its anatomy and dynamic function, while shielding infants from radiation exposure that can accompany other imaging techniques.

They enrolled 96 infants who had undergone brain MRIs as part of an unrelated study about neonatal brain development. The newborns had a range of medical conditions, including suspected hypoxic ischemic encephalopathy, cardiac disease and seizures/movement disorders.

Forty-nine of the infants were born preterm; at the time of the MRI, their corrected mean gestational age was 38.4 weeks. Forty-seven of the newborns were born full term; they received MRIs at 1.7 weeks of age. The airway structures of interest included the nasopharynx (the upper part of the pharynx), oropharynx (located at the back of the mouth behind the oral cavity), hypopharynx (the entrance into the esophagus), adenoids and tonsils. The team displayed the volumetric imaging in three perpendicular planes and a three-dimensional model.

“Nasopharyngeal volume of full-term infants was 495.6 mm, compared with 221.1 mm in preterm infants. Oropharyngeal volume of full-term infants was 313.6 mm, compared with 179.3 mm in preterm infants,” Smitthimedhin says.

Aided by volumetric 3D data that more accurately measures airway and lymphoid tissue, the team proposes to study a larger group of infants to determine whether narrowing of the uppermost airways predisposes very young children to experiencing OSA later in life.

“Ultimately, our goal is to incorporate dedicated, dynamic MR imaging of the airway while children sleep, which would provide real-time, detailed information about the changes associated with sleep. This innovation holds the promise of leading to more accurate, non-invasive diagnosis of OSA in infants,” says Dorothy Bulas, M.D., chief of Diagnostic Imaging and Radiology at Children’s National.

Children’s National study co-authors include Radiologist Matthew Whitehead, M.D.; University of Maryland student Mahya Bigdeli; Pulmonologist Gustavo Nino, M.D.; Pulmonologist Geovanny Perez, M.D,; and Hansel Otero, who was at Children’s National when the research work was performed but now works at Children’s Hospital of Philadelphia.

the cerebral blood flow (CBF) maps, corresponding anatomical image aligned to the CBF map, and the regions of interest examined

Tracking preemies’ blood flow to monitor brain maturation

Blood is the conduit through which our cells receive much of what they need to grow and thrive. The nutrients and oxygen that cells require are transported by this liquid messenger. Getting adequate blood flow is especially important during the rapid growth of gestation and early childhood – particularly for the brain, the weight of which roughly triples during the last 13 weeks of a typical pregnancy. Any disruption to blood flow during this time could dramatically affect the development of this critical organ.

Now, a new study by Children’s National Health System researchers finds that blood flow to key regions of very premature infants’ brains is altered, providing an early warning sign of disturbed brain maturation well before such injury is visible on conventional imaging. The prospective, observational study was published online Dec. 4, 2017 by The Journal of Pediatrics.

“During the third trimester of pregnancy, the fetal brain undergoes an unprecedented growth spurt. To power that growth, cerebral blood flow increases and delivers the extra oxygen and nutrients needed to nurture normal brain development,” says Catherine Limperopoulos, Ph.D., director of the Developing Brain Research Laboratory at Children’s National and senior author of the study. “In full-term pregnancies, these critical brain structures mature inside the protective womb where the fetus can hear the mother and her heartbeat, which stimulates additional brain maturation. For infants born preterm, however, this essential maturation process happens in settings often stripped of such stimuli.”

The challenge: How to capture what goes right or wrong in the developing brains of these very fragile newborns? The researchers relied on arterial spin labeling (ASL) magnetic resonance (MR) imaging, a noninvasive technique that labels the water portion of blood to map how blood flows through infants’ brains in order to describe which regions do or do not receive adequate blood supply. The imaging work can be done without a contrast agent since water from arterial blood itself illuminates the path traveled by cerebral blood.

“In our study, very preterm infants had greater absolute cortical cerebral blood flow compared with full-term infants. Within regions, however, the insula (a region critical to experiencing emotion), anterior cingulate cortex (a region involved in cognitive processes) and auditory cortex (a region involved in processing sound) for preterm infants received a significantly decreased volume of blood, compared with full-term infants. For preterm infants, parenchymal brain injury and the need for cardiac vasopressor support both were correlated with decreased regional CBF,” Limperopoulos adds.

The team studied 98 preterm infants who were born June 2012 to December 2015, were younger than 32 gestational weeks at birth and who weighed less than 1,500 grams. They matched those preemies by gestational age with 104 infants who had been carried to term. The brain MRIs were performed as the infants slept.

Blood flows where it is needed most with areas of the brain that are used more heavily commandeering more oxygen and nutrients. Thus, during brain development, CBF is a good indicator of functional brain maturation since brain areas that are the most metabolically active need more blood.

the cerebral blood flow (CBF) maps, corresponding anatomical image aligned to the CBF map, and the regions of interest examined

This figure represents the cerebral blood flow (CBF) maps, corresponding anatomical image aligned to the CBF map, and the regions of interest examined. The scale indicates the quantitative value of the CBF map and is expressed in mL/100g/min. The data are from a preterm infant scanned at term age without evidence of brain injury. The insula (see black arrows in panel ‘D’) may be particularly vulnerable to the added stresses of the preterm infant’s life outside the womb.
Credit: M. Bouyssi-Kobar, et al., The Journal of Pediatrics.

“The ongoing maturation of the newborn’s brain can be seen in the distribution pattern of cerebral blood flow, with the greatest volume of blood traveling to the brainstem and deep grey matter,” says Marine Bouyssi-Kobar, M.S., the study’s lead author. “Because of the sharp resolution provided by ASL-MR images, our study finds that in addition to the brainstem and deep grey matter, the insula and the areas of the brain responsible for sensory and motor functions are also among the most oxygenated regions. This underscores the critical importance of these brain regions in early brain development. In preterm infants, the insula may be particularly vulnerable to the added stresses of life outside the womb.”

Of note, compromised regional brain structures in adults are implicated in multiple neurodevelopmental disorders. “Altered development of the insula and anterior cingulate cortex in newborns may represent early warning signs of preterm infants at greater risk for long-term neurodevelopmental impairments,” Limperopoulos says.

Research reported in this post was supported by the Canadian Institutes of Health Research, MOP-81116; the SickKids Foundation, XG 06-069; and the National Institutes of Health under award number R01 HL116585-01.

Javad Nazarian

Liquid biopsy spots aggressive brainstem cancer earlier

Javad Nazarian

A Children’s National research team led by Javad Nazarian, Ph.D., M.S.C., tested whether circulating tumor DNA in patients’ blood and cerebrospinal fluid would provide an earlier warning that pediatric brainstem tumors were growing.

A highly aggressive pediatric brain cancer can be spotted earlier and reliably by the genetic fragments it leaves in biofluids, according to a study presented by Children’s National Health System researchers at the Society for Neuro-Oncology (SNO) 2017 Annual Meeting. The findings may open the door to non-surgical biopsies and a new way to tell if these tumors are responding to treatment.

Children diagnosed with diffuse midline histone 3 K27M mutant (H3K27M) glioma face a poor prognosis with a median survival time of only nine months after the pediatric brainstem cancer is diagnosed. Right now, clinicians rely on magnetic resonance imaging (MRI) to gauge how tumors are growing, but MRI can miss very small changes in tumor size. The Children’s research team led by Javad Nazarian, Ph.D., M.S.C., scientific director of Children’s Brain Tumor Institute, tested whether circulating tumor DNA in patients’ blood and cerebrospinal fluid would provide an earlier warning that tumors were growing. Just as a detective looks for fingerprints left at a scene, the new genetic analysis technique can detect telltale signs that tumors leave behind in body fluids.

“We continue to push the envelope to find ways to provide hope for children and families who right now face a very dismal future. By identifying these tumors when they are small and, potentially more responsive to treatment, our ultimate aim is to help children live longer,” says Eshini Panditharatna, B.A., study lead author. “In addition, we are hopeful that the comprehensive panel of tests we are constructing could identify which treatments are most effective in shrinking these deadly tumors.”

The researchers collected biofluid samples from 22 patients with diffuse intrinsic pontine glioma (DIPG) who were enrolled in a Phase I, Pacific Pediatric Neuro-Oncology Consortium clinical trial. Upfront and longitudinal plasma samples were collected with each MRI at various stages of disease progression. The team developed a liquid biopsy assay using a sensitive digital droplet polymerase chain reaction system that precisely counts individual DNA molecules.

“We detected H3K27M, a major driver mutation in DIPG, in about 80 percent of cerebrospinal fluid and plasma samples,” Panditharatna says. “Similar to adults with central nervous system (CNS) cancers, cerebrospinal fluid of children diagnosed with CNS cancers has high concentrations of circulating tumor DNA. However, after the children underwent radiotherapy, there was a dramatic decrease in circulating tumor DNA for 12 of the 15 patients (80 percent) whose temporal plasma was analyzed.”

Nazarian, the study senior author adds: “Biofluids, like plasma and cerebrospinal fluid, are suitable media to detect and measure concentrations of circulating tumor DNA for this type of pediatric glioma. Liquid biopsy has the potential to complement tissue biopsies and MRI evaluation to provide earlier clues to how tumors are responding to treatment or recurring.”

Support for this liquid biopsy study was provided by the V Foundation, Goldwin Foundation, Pediatric Brain Tumor Foundation, Smashing Walnuts Foundation, the Zickler Family Foundation, the Piedmont Community Foundation, the Musella Foundation, the Mathew Larson Foundation and Brain Tumor Foundation for Children.

An-Massaro

Continuous EEG monitoring better predicts HIE outcomes

An-Massaro

“What we were trying to determine with this study is whether evaluating the pattern of evolution of the aEEG as a whole provides more information compared with looking at snapshots in time,” explains the study’s senior author An N. Massaro, M.D.

For newborns who experience a serious complication that deprives their brain of oxygen, continuously monitoring brain activity and examining how the electrical signals evolve may be a more reliable way to identify infants most at risk for brain injury, compared with doing evaluations at discreet intervals, according to a prospective cohort study led by Children’s National Health System research-clinicians.

Amplitude-integrated electroencephalogram (aEEG) is a bedside tool that permits clinicians to monitor the complex electrical activity of the child’s brain over time. It’s a positive sign when an aEEG shows babies beginning to sleep and wake normally by the time they are 3 days old. Conversely, severely abnormal aEEG readings in the first days of life predict poor outcomes.

The Children’s team used aEEG with infants born with hypoxic-ischemic encephalopathy (HIE), one of the most severe complications that can affect full-term infants. During pregnancy, birth or shortly after birth, a hypoxic-ischemic event can occur that impedes blood flow and oxygen delivery to the brain, resulting in destruction of brain tissue. Cooling (therapeutic hypothermia) is now standard for newborns with HIE in order to stave off life-long consequences, but deaths and neurodevelopmental disability still can occur.

“We know whole-body cooling – or lowering the body’s temperature by about 3 degrees Celsius – can help vulnerable newborns survive and can protect their brains from suffering profound injuries,” says An N. Massaro, M.D., a Children’s National neonatologist and senior author of the study published online Sept. 28, 2017 in American Journal of Perinatology.  “What we were trying to determine with this study is whether evaluating the pattern of evolution of the aEEG as a whole provides more information compared with looking at snapshots in time.”

Eighty infants undergoing therapeutic cooling who met the inclusion criteria were enrolled in the five-year study, one of the largest such studies to date. The babies weighed more than 1,800 grams and were older than 35 weeks’ gestational age at birth, and either needed prolonged resuscitation after birth or had low APGAR scores – a measure of how well newborns fare outside the womb. Continuous recordings of EEG data occurred from the time of admission up to 12 hours after the infants’ temperatures were raised to normal and aEEG tracings were calculated.

After the therapeutic cooling blankets were removed, the infants underwent at least one magnetic resonance imaging (MRI) scan prior to discharge. During the routine follow-up check at about 18 months of age, the HIE survivors’ cognitive and motor skills were assessed using validated instruments.

Fifty-six of the infants in the study had favorable outcomes. Twenty-four infants had adverse outcomes, including 15 with severe brain injury detected by MRI and nine infants who died. These children had lower APGAR scores at five minutes, and were more likely to have severe HIE and to have experienced more frequent seizures.

“Infants whose aEEG abnormalities do not improve were at increased risk: Infants who do not reach a discontinuous background pattern by 15.5 hours of life, achieve cycling by 45.5 hours after birth and who fail to achieve continuous normal voltage by 78 hours after birth are most at risk for adverse outcomes,” Dr. Massaro says. “In addition to defining worrisome trends, we found that overall assessment of continuous aEEG readings through the course of hypothermia treatment provide the most meaningful predictive power. This means we can speak with families at the bedside with more confidence about their child’s outcomes after the infant undergoes cooling therapy.”

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Sarah Mulkey

Fetal MRI plus ultrasound assess Zika-related brain changes

Sarah Mulkey

Magnetic resonance imaging and ultrasound provide complementary data needed to assess ongoing changes to the brains of fetuses exposed to Zika in utero, says Sarah B. Mulkey, M.D., Ph.D.

For Zika-affected pregnancies, fetal magnetic resonance imaging (MRI) used in addition to standard ultrasound (US) imaging can better assess potential brain abnormalities in utero, according to research presented by Children’s National Health System during IDWeek 2017. In cases of abnormal brain structure, fetal MRI can reveal more extensive areas of damage to the developing brain than is seen with US.

“MRI and US provide complementary data needed to assess ongoing changes to the brains of fetuses exposed to Zika in utero,” says Sarah B. Mulkey, M.D., Ph.D., a fetal/neonatal neurologist at Children’s National Health System and lead author of the research paper. “In addition, our study found that relying on ultrasound alone would have given one mother the false assurance that her fetus’ brain was developing normally while the sharper MRI clearly pointed to brain abnormalities.”

As of Sept. 13, the Centers for Disease Control and Prevention (CDC) reported that 1,901 U.S. women were exposed to Zika at some point during their pregnancies but their infants appeared normal at birth. Another 98 U.S. women, however, gave birth to infants with Zika-related birth defects.  And eight more women had pregnancy losses with Zika-related birth defects, according to CDC registries.

The longitudinal neuroimaging study led by Children’s National enrolled 48 pregnant women exposed to the Zika virus in the first or second trimester whose infection was confirmed by reverse transcription polymerase chain reaction, which detects Zika viral fragments shortly after exposure, and/or Immunoglobulin M testing, which reveals antibodies the body produces to neutralize the virus. Forty-six of the study volunteers live in Barranquilla, Colombia, where Zika infection is endemic. Two women live in the Washington region and were exposed to Zika during travel elsewhere.

All of the women underwent at least one diagnostic imaging session while pregnant, receiving an initial MRI or US at 25.1 weeks’ gestational age. Thirty-six women underwent a second MRI/US imaging pair at roughly 31 weeks’ gestation. Children’s National radiologists read every image.

Three of 48 pregnancies, or 6 percent, were marked by abnormal fetal MRIs:

  • One fetus had heterotopias (clumps of grey matter located at the wrong place) and abnormal cortical indent (a deformation at the outer layer of the cerebrum, a brain region involved in consciousness). The US taken at the same gestational age for this fetus showed its brain was developing normally.
  • Another fetus had parietal encephalocele (an uncommon skull defect) and Chiari malformation Type II (a life-threatening structural defect at the base of the skull and the cerebellum, the part of the brain that controls balance). The US for this fetus also detected these brain abnormalities.
  • The third fetus had a thin corpus callosum (bundle of nerves that connects the brain’s left and right hemispheres), an abnormally developed brain stem, temporal cysts, subependymal heterotopias and general cerebral/cerebellar atrophy. This fetal US showed significant ventriculomegaly (fluid-filled structures in the brain that are too large) and a fetal head circumference that decreased sharply from the 32nd to 36th gestational week, a hallmark of microcephaly.

After they were born, infants underwent a follow-up MRI without sedation and US. For nine infants, these ultrasounds revealed cysts in the choroid plexus (cells that produce cerebrospinal fluid) or germinal matrix (the source for neurons and glial cells that migrate during brain development). And one infant’s US after birth showed lenticulostriate vasculopathy (brain lesions).

“Because a number of factors can trigger brain abnormalities, further studies are needed to determine whether the cystic changes to these infants’ brains are attributable to Zika exposure in the womb or whether some other insult caused these troubling results,” Dr. Mulkey says.

Spectral data shine light on placenta

preemie baby

A research project led by Subechhya Pradhan, Ph.D., aims to shed light on metabolism of the placenta, a poorly understood organ, and characterize early biomarkers of fetal congenital heart disease.

The placenta serves as an essential intermediary between a pregnant mother and her developing fetus, transporting in life-sustaining oxygen and nutrients, ferrying out waste and serving as interim lungs, kidneys and liver as those vital organs develop in utero.

While the placenta plays a vital role in supporting normal pregnancies, it remains largely a black box to science. A research project led by Subechhya Pradhan, Ph.D., and partially funded by a Clinical and Translational Science Institute Research Award aims to shed light on placenta metabolism and characterize possible early biomarkers of impaired placental function in fetal congenital heart disease (CHD), the most common type of birth defect.

“There is a huge information void,” says Pradhan, a research faculty member of the Developing Brain Research Laboratory at Children’s National Health System. “Right now, we do not have very much information about placenta metabolism in vivo. This would be one of the first steps to understand what is actually going on in the placenta at a biochemical level as pregnancies progress.”

The project Pradhan leads will look at the placentas of 30 women in the second and third trimesters of healthy, uncomplicated pregnancies and will compare them with placentas of 30 pregnant women whose fetuses have been diagnosed with CHD. As volunteers for a different study, the women are already undergoing magnetic resonance imaging, which takes detailed images of the placenta’s structure and architecture. The magnetic resonance spectroscopy scans that Pradhan will review show the unique chemical fingerprints of key metabolites: Choline, lipids and lactate.

Choline, a nutrient the body needs to preserve cellular structural integrity, is a marker of cell membrane turnover. Fetuses with CHD have higher concentrations of lactate in the brain, a telltale sign of a shortage of oxygen. Pradhan’s working hypothesis is that there may be differing lipid profiles and lactate levels in the placenta in pregnancies complicated by CHD.  The research team will extract those metabolite concentrations from the spectral scans to describe how they evolve in both groups of pregnant women.

“While babies born with CHD can undergo surgery as early as the first few days (or sometimes hours) of life to correct their hearts, unfortunately, we still see a high prevalence of neurodevelopmental impairments in infants with CHD. This suggests that neurological dysfunctional may have its origin in fetal life,” Pradhan says.

Having an earlier idea of which fetuses with CHD are most vulnerable has the potential to pinpoint which pregnancies need more oversight and earlier intervention.

Placenta spectral data traditionally have been difficult to acquire because the pregnant mother moves as does the fetus, she adds. During the three-minute scans, the research team will try to limit excess movement using a technique called respiratory gating, which tells the machine to synchronize image acquisition so it occurs in rhythm with the women’s breathing.

Catherine Limperopoulous

The brain’s fluid-filled spaces during growth

Catherine Limperopoulous

Catherine Limperopoulous, Ph.D., and her colleagues used volumetric MRIs to assess how the ventricles, cerebrospinal fluid and the rest of the fetal brain normally change over time.

The human brain is not one solid mass. Buried within its gray and white matter are a series of four interconnected chambers, called ventricles, which produce cerebrospinal fluid. These ventricles are readily apparent on the fetal ultrasounds that have become the standard of prenatal care in the United States and most developed countries around the world. Abnormalities in the ventricles’ size or shape – or both – can give doctors an early warning that fetal brain development might be going awry.

But what is abnormal? It is not always clear, says Catherine Limperopoulos, Ph.D., director of the Developing Brain Research Laboratory at Children’s National Health System. Limperopoulos explains that despite having many variations in fetal ventricles, some infants have completely normal neurodevelopmental outcomes later. On the other hand, some extremely subtle variations in shape and size can signal problems.

On top of these complications are the tools clinicians typically use to assess the ventricles. Limperopoulos explains that most early indications of ventricle abnormalities come from ultrasounds, but the finer resolution of magnetic resonance imaging (MRI) can provide a more accurate assessment of fetal brain development. Still, both standard MRI and ultrasound provide only two-dimensional pictures, making it difficult to quantify slight differences in the volume of structures.

To help solve these problems, Limperopoulos and her colleagues recently published a paper in Developmental Neuroscience that takes a different tack. The team performed volumetric MRIs – a technique that provides a precise three-dimensional measure of structural volumes – on the brains of healthy fetuses to assess how the ventricles, cerebrospinal fluid and the rest of the brain normally change over time. Limperopoulos’ team recently performed a similar study to assess normal volumetric development in the brain’s solid tissues.

Previous studies published on comparable topics typically used information gathered from subjects who initially had clinical concerns but eventually were dismissed from these studies for not having worrisome diagnoses in the end. This might not truly reflect a typical population of pregnant women, Limperopoulos says.

Working with 166 pregnant women with healthy pregnancies spanning from 18 to 40 weeks gestation, the researchers performed volumetric MRIs on their singleton fetuses that covered every week of this second half of pregnancy. This technique allowed them to precisely calculate the volumes of structures within the fetal brain and get an idea of how these volumes changed over time within the group.

Their results show that over the second and third trimester:

  • The lateral ventricles, the largest ventricles found in the cerebrum with one for each brain hemisphere, grew about two-fold;
  • The third ventricle, found in the forebrain, grew about 23-fold;
  • The fourth ventricle, found in the hindbrain, grew about eight-fold;
  • And the extra-axial cerebrospinal fluid, found under the lining of the brain, increased about 11-fold.

The total brain volume increased 64-fold over this time, with the parenchyma – the solid brain tissue that encompasses gray and white matter – growing significantly faster than the cerebrospinal fluid-filled spaces.

Limperopoulos points out that the ability to measure the growth of the brain’s fluid-filled spaces relative to the surrounding brain tissue can provide critical information to clinicians caring for developing fetuses. In most cases, knowing what is normal allows doctors to reassure pregnant women that their fetus’ growth is on track. Abnormalities in these ratios can provide some of the first signals to alert doctors to blockages in cerebrospinal fluid flow, abnormal development, or the loss of brain tissue to damage or disease. Although the neurodevelopmental outcomes from each of these conditions can vary significantly, traditional ultrasounds or MRIs might not be able to distinguish these possibilities from each other. Being able to differentiate why cerebrospinal fluid spaces have abnormal shapes or sizes might allow doctors to better counsel parents, predict neurological outcomes, or potentially intervene before or after birth to mitigate brain damage.

“By developing a better understanding of what’s normal,” Limperopoulos says, “we can eventually identify reliable biomarkers of risk and guide interventions to minimize risks for vulnerable fetuses.”

Setting a baseline for healthy brain development

Catherine Limperopoulos, Ph.D., and colleagues performed the largest magnetic resonance imaging study of normal fetal brains in the second and third trimesters of pregnancy.

Starting as a speck barely visible to the naked eye and ending the in utero phase of its journey at an average weight of 7.5 pounds, the growth of the human fetus is one of the most amazing events in biology. Of all the organs, the fetal brain undergoes one of the most rapid growth trajectories, expanding over 40 weeks from zero to 100 billion neurons — about as many brain cells as there are stars in the Milky Way Galaxy.

This exponential growth is part of what gives humans our unique abilities to use language or have abstract thoughts, among many other cognitive skills. It also leaves the brain extremely vulnerable should disruptions occur during fetal development. Any veering off the developmental plan can lead to a cascade of results that have long-lasting repercussions. For example, studies have shown that placental insufficiency, or the inability of the placenta to supply the fetus with oxygen and nutrients in utero, is associated with attention deficit hyperactivity disorder, autism, and schizophrenia.

Recent research has identified differences in the brains of people with these disorders compared with those without. Despite the almost certain start of these conditions within the womb, they have remained impossible to diagnose until children begin to show clinical symptoms. If only researchers could spot the beginnings of these problems early in development, says Children’s National Health System researcher Catherine Limperopoulos, Ph.D., they might someday be able to develop interventions that could turn the fetal brain back toward a healthy developmental trajectory.

“Conventional tools like ultrasound and magnetic resonance imaging (MRI) can identify structural brain abnormalities connected to these problems, but by the time these differences become apparent, the damage already has been done,” Limperopoulos says. “Our goal is to be able to pick up very early deviations from normal in the high-risk pregnancy before an injury to the fetus might become permanent.”

Before scientists can recognize abnormal, she adds, they first need to understand what normal looks like.

In a new study published in Cerebral Cortex, Limperopoulos and colleagues begin to tackle this question through the largest MRI study of normal fetal brains in the second and third trimesters of pregnancy. While other studies have attempted to track normal fetal brain growth, that research has not involved nearly as many subjects and typically relied on data collected when fetuses were referred for MRIs for a suspected problem. When the suspected abnormality was ruled out by the scan, these “quasi-controls” were considered “normal” — even though they may be at risk for problems later in life, Limperopoulos explains.

By contrast, the study she led recruited 166 healthy pregnant women from nearby low-risk obstetrics practices. Each woman had an unremarkable singleton pregnancy and ended up having a normal full-term delivery, with no evidence of problems affecting either the mother or fetus over the course of 40 weeks.

At least one time between 18 and 39 gestational weeks, the fetuses carried by these women underwent an MRI scan of their brains. The research team developed complex algorithms to account for movement (since neither the mothers nor their fetuses were sedated during scans) and to convert the two-dimensional images into three dimensions. They used the information from these scans to measure the increasing volumes of the cerebellum, an area of the brain connected to motor control and known to mediate cognitive skills; as well as regions of the cerebrum, the bulk of the brain, that is pivotal for movement, sensory processing, olfaction, language, and learning and memory.

Their results in uncomplicated, full-term pregnancies show that over 21 weeks in the second half of pregnancy, the cerebellum undergoes an astounding 34-fold increase in size. In the cerebrum, the fetal white matter, which connects various brain regions, grows 22-fold. The cortical gray matter, key to many of cerebrum’s functions, grows 21-fold. And the deep subcortical structures (thalamus and basal ganglia), important for relaying sensory information and coordination of movement and behavior, grow 10-fold. Additional examination showed that the left hemisphere has a larger volume than the right hemisphere early in development, but sizes of the left and right brain halves were equal by birth.

By developing similar datasets on high-risk pregnancies or births—for example, those in which fetuses are diagnosed with a problem in utero, mothers experience a significant health problem during pregnancy, babies are born prematurely, or fetuses have a sibling diagnosed with a health problem with genetic risk, such as autism—Limperopoulos says that researchers might be able to spot differences during gestation and post-natal development that lead to conditions such as schizophrenia, attention deficit hyperactivity disorder and autism spectrum disorder.

Eventually, researchers may be able to develop fixes so that babies grow up without life-long developmental issues.

“Understanding ‘normal’ is really opening up opportunities for us to begin to precisely pinpoint when things start to veer off track,” Limperopolous says. “Once we do that, opportunities that have been inaccessible will start to present themselves.”