MRI patterns of hypoxic-ischemic brain injury in preterm and full term infants - classical and less common MR findings

Unusual cerebral intraventricular hemorrhage and cardiomyopathy related to congenital cytomegalovirus from non-primary maternal infection: a case report

BACKGROUND

Congenital cytomegalovirus (cCMV) infection, resulting from non-primary maternal infection or reactivation during pregnancy, can cause serious fetal abnormalities, complications in the immediate neonatal period, and severe sequelae later in childhood. Maternal non-primary cytomegalovirus infection in pregnancy is transmitted to the fetus in 0.5-2% of cases (1).

CASE PRESENTATION

An African full term male newbornwas delivered by emergency caesarean section. Due to signs of asphyxia at birth and clinical moderate encephalopathy, he underwent therapeutic hypothermia. Continuous full video-electroencephalography monitoring showed no seizures during the first 72 h, however, soon after rewarming, he presented refractory status epilepticus due to an intracranial hemorrhage, related to severe thrombocytopenia. The patient also presented signs of sepsis (hypotension and signs of reduced perfusions). An echocardiography revealed severe cardiac failure with an ejection fraction of 33% and signs suggestive of cardiomyopathy. Research for CMV DNA Polymerase Chain Reaction (PCR) on urine, blood, cerebrospinal fluid, and nasopharyngeal secretions was positive.The mother had positive CMV IgG with negative IgM shortly before pregnancy. Serology for CMV was therefore not repeated during pregnancy, but CMV DNA performed on the Guthrie bloodspot taken at birth yielded a positive result, confirming the intrauterine transmission and congenital origin of the infection. The baby was discharged in good general condition and follow up showed a normal neurodevelopmental outcome at 9 months.

CONCLUSION

Although uncommon, congenital cytomegalovirus infection should be included in the differential diagnosis of intraventricular hemorrhage and cardiomyopathy. Furthermore, this case highlights the possible severity of congenital cytomegalovirus infection, even in cases of previous maternal immunity.

Inter-alpha Inhibitor Proteins Ameliorate Brain Injury and Improve Behavioral Outcomes in a Sex-Dependent Manner After Exposure to Neonatal Hypoxia Ischemia in Newborn and Young Adult Rats

Hypoxic-ischemic (HI) brain injury is a major contributor to neurodevelopmental morbidities. Inter-alpha inhibitor proteins (IAIPs) have neuroprotective effects on HI-related brain injury in neonatal rats. However, the effects of treatment with IAIPs on sequential behavioral, MRI, and histopathological abnormalities in the young adult brain after treatment with IAIPs in neonates remain to be determined. The objective of this study was to examine the neuroprotective effects of IAIPs at different neurodevelopmental stages from newborn to young adults after exposure of neonates to HI injury. IAIPs were given as 11-sequential 30-mg/kg doses to postnatal (P) day 7-21 rats after right common carotid artery ligation and exposure to 90 min of 8% oxygen. The resulting brain edema and injury were examined by T2-weighted magnetic resonance imaging (MRI) and cresyl violet staining, respectively. The mean T2 values of the ipsilateral hemisphere from MRI slices 6 to 10 were reduced in IAIP-treated HI males + females on P8, P9, and P10 and females on P8, P9, P10, and P14. IAIP treatment reduced hemispheric volume atrophy by 44.5 ± 29.7% in adult male + female P42 rats and improved general locomotor abilities measured by the righting reflex over time at P7.5, P8, and P9 in males + females and males and muscle strength/endurance measured by wire hang on P16 in males + females and females. IAIPs provided beneficial effects during the learning phase of the Morris water maze with females exhibiting beneficial effects. IAIPs confer neuroprotection from HI-related brain injury in neonates and even in adult rats and beneficial MRI and behavioral benefits in a sex-dependent manner.

Distinctive Neuroimaging Pattern in Term Newborns With Neonatal Placental Encephalopathy: A Case Series

BACKGROUND

Identifying antepartum versus intrapartum timing and the cause of neonatal encephalopathy (NE) often remains elusive owing to our limited understanding of the underlying pathophysiological processes and lack of appropriate biomarkers.

OBJECTIVES

This retrospective observational study describes a case series of term newborns with NE who displayed a recognizable magnetic resonance imaging pattern of immediately postnatal brain abnormalities that rapidly evolved toward cavitation. Our aim is to (1) report this neuroimaging pattern, (2) look for placental determinants, and (3) depict the outcome.

DESIGN/METHODS

This is a unicentric retrospective case series reporting the clinical, radiological, and laboratory findings of NE associated with a distinctive neuroimaging pattern, that is, immediately postnatal extensive corticosubcortical T2 hyperintensities, followed by rapid corticosubcortical cavitation that does not match the neuroimaging picture of intrapartum hypoxic-ischemic encephalopathy (HIE).

RESULTS

Seven term newborns presented bilateral corticosubcortical hyperintensities that were detected on T2 between day of life (DOL) 1-4, which rapidly evolved toward cystic encephalomalacia, that is, between DOL9 and DOL12. All these newborns presented with moderate/severe NE. The outcome was either neonatal death or quadriplegic cerebral palsy and epilepsy. None of the reported patients fulfilled the criteria of a high likelihood of acute intrapartum hypoxic-ischemic or quadriplegic cerebral palsy. All these newborns were exposed to chronic and/or acute placental inflammation and/or hypoxic-ischemic.

CONCLUSIONS

To further define the antepartum causes of NE, early neuroimaging and a placental examination are recommended. Brain T2 hyperintense injuries before DOL4 followed by rapid cavitation before DOL12 might be biomarkers of NE from an antepartum/placental origin.

Magnetic resonance imaging spectrum of perinatal hypoxic-ischemic brain injury

Perinatal hypoxic–ischemic brain injury results in neonatal hypoxic–ischemic encephalopathy and serious long-term neurodevelopmental sequelae. Magnetic resonance imaging (MRI) of the brain is an ideal and safe imaging modality for suspected hypoxic–ischemic injury. The pattern of injury depends on brain maturity at the time of insult, severity of hypotension, and duration of insult. Time of imaging after the insult influences the imaging findings. Mild to moderate hypoperfusion results in germinal matrix hemorrhages and periventricular leukomalacia in preterm neonates and parasagittal watershed territory infarcts in full-term neonates. Severe insult preferentially damages the deep gray matter in both term and preterm infants. However, associated frequent perirolandic injury is seen in term neonates. MRI is useful in establishing the clinical diagnosis, assessing the severity of injury, and thereby prognosticating the outcome. Familiarity with imaging spectrum and insight into factors affecting the injury will enlighten the radiologist to provide an appropriate diagnosis.

Non-neoplastic intracranial cystic lesions: not everything is an arachnoid cyst

Intracranial cystic lesions are common findings on neuroimaging examinations, arachnoid cysts being the most common type of such lesions. However, various lesions of congenital, infectious, or vascular origin can present with cysts. In this pictorial essay, we illustrate the main causes of non-neoplastic intracranial cystic lesions, discussing their possible differential diagnoses as well as their most relevant imaging aspects.

Neonatal Hypoxic-Ischemic Encephalopathy Yields Permanent Deficits in Learning Acquisition: A Preclinical Touchscreen Assessment

Neonatal hypoxic-ischemic encephalopathy (HIE) remains a common problem world-wide for infants born at term. The impact of HIE on long-term outcomes, especially into adulthood, is not well-described. To facilitate identification of biobehavioral biomarkers utilizing a translational platform, we sought to investigate the impact of HIE on executive function and cognitive outcomes into adulthood utilizing a murine model of HIE. HIE mice (unilateral common carotid artery occlusion to induce ischemia, followed by hypoxia with a FiO2 of 0.08 for 45 min) and control mice were tested on discrimination and reversal touchscreen tasks (using their noses) shown to be sensitive to loss of basal ganglia or cortical function, respectively. We hypothesized that the HIE injury would result in deficits in reversal learning, revealing complex cognitive and executive functioning impairments. Following HIE, mice had a mild discrimination impairment as measured by incorrect responses but were able to learn the paradigm to similar levels as controls. During reversal, HIE mice required significantly more total trials, errors and correction trials across the paradigm. Analysis of specific stages showed that reversal impairments in HIE were driven by significant increases in all measured parameters during the late learning, striatal-mediated portion of the task. Together, these results support the concept that HIE occurring during the neonatal period results in abnormal neurodevelopment that persists into adulthood, which can impact efficient associated learning. Further, these data show that utilization of an established model of HIE coupled with touchscreen learning provides valuable information for screening therapeutic interventions that could mitigate these deficits to improve the long-term outcomes of this vulnerable population.

Magnetic resonance imaging features of four neonates with total brain injury

PURPOSE

The most severe form of profound asphyxia in neonates is now known as "total brain injury," which forms part of the clinical spectrum of hypoxic-ischemic encephalopathy (HIE). Although the magnetic resonance (MR) imaging features of total brain injury remain to be determined, a widespread hyperintensity of the supratentorial brain, known as the "white cerebrum sign," has been reported in diffusion-weighted images (DWI).

METHODS

We examined four neonates who developed severe profound asphyxia.

RESULTS

In the first week of life, all neonates showed the white cerebrum sign on DWI. A follow-up of these cases over a period of 1 month revealed diffuse bilateral multicystic encephalomalacia (MCE) as well as shrinkage of the basal ganglia and thalami (BG/T). These MR findings were common to all neonates, and all the neonates had severe adverse clinical outcomes.

CONCLUSION

Neonates, who exhibit the white cerebrum sign on MR imaging due to profound asphyxia, develop major disabilities, and MCE with shrinkage of the BG/T suggests miserable outcomes.

The influence of anesthetics on substantia nigra tyrosine hydroxylase expression and tau phosphorylation in the hypoxic-ischemic near-term lamb

BackgroundGeneral anesthetics could protect key neurotransmitter systems, such as the dopaminergic system, from hypoxic-ischemic encephalopathy (HIE) by limiting excessive glutamatergic neurotransmission. However, anesthetics may adversely affect inflammation and tau phosphorylation.MethodsA near-term sheep model of HIE by umbilical cord occlusion (UCO) under anesthesia was used. The effect of propofol and isoflurane on the dopaminergic neurotransmitter phenotype in the substantia nigra (SN) was studied using tyrosine hydroxylase immunohistochemistry. The overall microglial response and tau phosphorylation were also measured in the SN, surrounding the midbrain gray matter structures and the hippocampal white matter.ResultsThe isoflurane-treated UCO group had fewer tyrosine hydroxylase-expressing neurons in the SN at 8 h after the insult than the propofol-treated UCO or sham-operated groups (P<0.05). The microglial response was unchanged in the SN region. In the thalamus and the hippocampal stratum moleculare layer, the propofol-treated UCO group had a lower microglial response than the corresponding sham-operated group. Both UCO and the use of anesthetics additively increased tau phosphorylation in the SN region, thalamus, and hippocampus.ConclusionThe choice of anesthetics is important for an emergency C-section. Propofol could potentially protect the dopaminergic neurotransmitter phenotype within the SN at the cost of a widespread increase in tau phosphorylation.

Mild prenatal hypoxia-ischemia leads to social deficits and central and peripheral inflammation in exposed offspring

Hypoxic-ischemic encephalopathy (HIE) resulting from intrauterine or perinatal hypoxic-ischemia (HI) is a leading cause of long-term neonatal neurodisability. While most studies of long-term outcome have focused on moderate and severe HIE in term infants, recent work has shown that those with mild HIE may have subtle neurological impairments. However, the impact of mild HI on pre-term infants is much less clear given that pre-term birth is itself a risk factor for neurodisability. Here we show that mild HI insult alters behaviour, inflammation and the corticosterone stress response in a rat model of pre-term HIE. Mild HI exposure led to social deficits in exposed offspring at postnatal day 30, without impairments in the novel object recognition test nor in the open field test. This was also accompanied by elevations in circulating adrenocorticotropic hormone and corticosterone indicating an exaggerated stress response. There were also elevations in il-1β and il-6 but not tnf-α mRNA and protein in the brain and blood samples. In summary we find that a mild HI exposure leads to social deficits, central and peripheral inflammation, and an abnormal corticosterone response which are three core features of autism spectrum disorder. This shows that mild HI exposure may be a risk factor for an abnormal neurodevelopmental outcome in pre-term offspring.

25 years of research on global asphyxia in the immature rat brain

Hypoxic-ischemic encephalopathy remains a common cause of brain damage in neonates. Preterm infants have additional complications, as prematurity by itself increases the risk of encephalopathy. Currently, therapy for this subset of asphyxiated infants is limited to supportive care. There is an urgent need for therapies in preterm infants - and for representative animal models for preclinical drug development. In 1991, a novel rodent model of global asphyxia in the preterm infant was developed in Sweden. This method was based on the induction of asphyxia during the birth processes itself by submerging pups, still in the uterine horns, in a water bath followed by C-section. This insult occurs at a time-point when the rodent brain maturity resembles the brain of a 22-32 week old human fetus. This model has developed over the past 25 years as an established model of perinatal global asphyxia in the early preterm brain. Here we summarize the knowledge gained on the short- and long-term neuropathological and behavioral effects of asphyxia on the immature central nervous system.

Nitric Oxide Production in the Striatum and Cerebellum of a Rat Model of Preterm Global Perinatal Asphyxia

Encephalopathy due to perinatal asphyxia (PA) is a major cause of neonatal morbidity and mortality in the period around birth. Preterm infants are especially at risk for cognitive, attention and motor impairments. Therapy for this subgroup is limited to supportive care, and new targets are thus urgently needed. Post-asphyxic excitotoxicity is partially mediated by excessive nitric oxide (NO) release. The aims of this study were to determine the timing and distribution of nitric oxide (NO) production after global PA in brain areas involved in motor regulation and coordination. This study focused on the rat striatum and cerebellum, as these areas also affect cognition or attention, in addition to their central role in motor control. NO/peroxynitrite levels were determined empirically with a fluorescent marker on postnatal days P5, P8 and P12. The distributions of neuronal NO synthase (nNOS), cyclic guanosine monophosphate (cGMP), astroglia and caspase-3 were determined with immunohistochemistry. Apoptosis was additionally assessed by measuring caspase-3-like activity from P2-P15. On P5 and P8, increased intensity of NO-associated fluorescence and cGMP immunoreactivity after PA was apparent in the striatum, but not in the cerebellum. No changes in nNOS immunoreactivity or astrocytes were observed. Modest changes in caspase-3-activity were observed between groups, but the overall time course of apoptosis over the first 11 days of life was similar between PA and controls. Altogether, these data suggest that PA increases NO/peroxynitrite levels during the first week after birth within the striatum, but not within the cerebellum, without marked astrogliosis. Therapeutic benefits of interventions that reduce endogenous NO production would likely be greater during this time frame.

First Experience with Neonatal Examinations with the Use of MR-Compatible Incubator

Background

Since 2003, very few publications have described brain examinations using neonatal MR-compatible incubator (INC). The authors present their first experience in these examinations, not limited to brain scans, with the use of an incubator equipped not only with head coil, but also with a coil designed for examinations of the spinal canal and spinal cord as well as the whole body, at the Institute of Mother and Child in Warsaw.

Material/Methods

Examinations were performed in 27 newborns (12 girls, 15 boys). Most of the neonates were prematurely born: 19 (70.4%) were born at gestational age of 23–37 weeks, mean of 30 weeks. They were examined at the corrected age of 26 weeks–1 month, mean of 36 weeks. Body weight of the newborns on the day of the study was 600–4,300 g, mean of 2,654 g. The study was performed with a GE Signa HDxT 1.5 T system with the use of a Nomag IC 1.5 incubator by Lammers Medical Technology Co., equipped with three coils: an eight-channel, phased-array head coil and a twelve-channel phased-array coil for the whole body, consisting of an eight-channel coil integrated in the incubator and a separate four-channel surface coil.

Results

Of the 27 children, 25 (92.6%) required a brain scan. Two children (7.4%) were referred to MRI for assessment of the spinal canal and the abdomen. We compared the results of transfontanelle ultrasound and MRI scans in 21 children. MRI provided significantly more diagnostic information in 18 cases (85.7%); in 3 cases (14.3%), no additional knowledge about the pathology was provided by the exam.

Conclusions

The MR-compatible incubator increases the availability of MRI to newborns, especially premature newborns and those with low and extremely low body weight, for whom MR examinations are necessary to determine the extent of changes, not limited to the central nervous system, as well as to establish prognosis. Dedicated neonatal coils integrated with the incubator permit more accurate diagnosis than the previously used adult coils.

Recommendations regarding imaging of the central nervous system in fetuses and neonates

An abnormal presentation of the central nervous system in a fetus during a screening examination is an indication for extended diagnosis, the aim of which is to explain the character of such an anomaly (a congenital defect, destructive effect of intrauterine infection or abnormality with reasons that are difficult to explain). Knowledge of normal development sequence of the fetal brain, which is discussed in this paper, is the basis for correct interpretation of imaging findings. Together with the increase in survival of preterm neonates, a high risk of early brain damage is still a problem in this extremely immature population. Therefore, imaging examinations become necessary. The paper presents intrauterine and postnatal risk factors of early brain damage as well as classification of such lesions, of hemorrhagic and hypoxic-ischemic etiology. The diagnosis of the cerebellum damage, which is currently believed to be a significant cause of autism, is emphasized. The evolution of lesions over time is also presented. Moreover, the elements of diagnosis important for prognosis are stressed. The standards of imaging examinations of the central nervous system include the schedule of ultrasound examinations and provide indications for extended diagnosis with the use of magnetic resonance imaging.