Prenatal MR imaging features of isolated cerebellar haemorrhagic lesions

Prenatal Diagnosis and Neurodevelopmental Outcome in Isolated Cerebellar Hypoplasia of Suspected Hemorrhagic Etiology: a Retrospective Cohort Study

Data about the neurological prognosis of isolated cerebellar hypoplasia in utero are scant and inconsistent. In this monocentric retrospective study, we describe the neurodevelopmental outcomes in a series of children with isolated cerebellar hypoplasia of presumably hemorrhagic origin prenatally detected with fetal magnetic resonance imaging (fMRI). We retrospectively reviewed the charts of all the pregnant women who were referred for a neurological consultation, diagnosed with fetal encephalic malformation/disruption between 2010 and 2020 in the Fetal Therapy Unit of our institution. Fetal MRI (fMRI) was performed in all the pregnancies. Fetuses with cerebellar hypoplasia presumably of hemorrhagic origin were selected for the study. Fetuses exposed to alcohol or with additional malformations in other cerebral or body areas were excluded. All the infants received the postpartum follow-up care adopted in our center, including post-natal MRI, serial neurological examinations, standardized neurodevelopmental tests, and regular parental interviews. Cognitive functions were tested with GRIFFITHS II, WPPSI-III, and WISC-IV according to the child's age. A total of 14 pregnant women out of 479 fetal consultations were eligible and included in the study group. In 57% of cases, the etiology of the hemorrhage was unknown. In 21% of cases, it was attributed to a blood transfusion, while in the remaining ones, it was attributed to maternal predisposing factors. Among the survivors, two infants were excluded for prematurity, and two were lost to follow-up. Ten patients were thus included in the study. Six patients had normal neurodevelopment and cognition, and three presented mild-moderate neurological signs, i.e., mild dyspraxia and visuoperceptual impairment. Only one child had a severe outcome, i.e., autism spectrum disorder. The cerebellum is particularly vulnerable to disruptions throughout its prolonged development. Extreme caution must be used in prenatal counseling considering that in the acute phase, lesion extension and vermis involvement can be overestimated with fMRI. In cases of uncertainty, performing an additional fMRI could be advisable after 4-8 weeks. However, in our series, infants with isolated cerebellar hypoplasia tended to have a favorable prognosis. Nevertheless, a long-term follow-up is needed and should include a postnatal brain MRI, serial neurological examinations, and neurodevelopmental tests at least up to school age.

Perinatal and long-term outcome of fetal intracranial hemorrhage: systematic review and meta-analysis

OBJECTIVE

Fetal intracranial hemorrhage (ICH) is associated with an increased risk of perinatal mortality and morbidity. Healthcare professionals often find it challenging to counsel parents due to its rarity and diverse presentation. The aim of this systematic review and meta-analysis was to investigate the perinatal outcome of fetuses with ICH.

METHODS

MEDLINE, EMBASE, ClinicalTrials.gov and The Cochrane Library databases were searched. Inclusion criteria were studies reporting the outcome of fetuses, newborns and infants diagnosed with ICH. The primary outcome was perinatal death (PND), defined as the sum of intrauterine (IUD) and neonatal death (NND). The secondary outcomes were stillbirth, NND, IUD, termination of pregnancy, need for surgery/shunting at birth, cerebral palsy (defined according to the European Cerebral Palsy Network and classified as diplegia, hemiplegia, quadriplegia, dyskinetic or mixed), neurodevelopmental delay and intact survival. All outcomes were explored in the included fetuses with ICH. A subgroup analysis according to the location of the hemorrhage (intra-axial and extra-axial) was also planned. Meta-analysis of proportions was used to combine data, and pooled proportions and their 95% CI were reported.

RESULTS

Sixteen studies (193 fetuses) were included in the meta-analysis. PND occurred in 14.6% (95% CI, 7.3-24.0%) of fetuses with ICH. Among liveborn cases, 27.6% (95% CI, 12.5-45.9%) required shunt placement or surgery after birth and 32.0% (95% CI, 22.2-42.6%) had cerebral palsy. Furthermore, 16.7% (95% CI, 8.4-27.2%) of cases had mild neurodevelopmental delay, while 31.1% (95% CI, 19.0-44.7%) experienced severe adverse neurodevelopmental outcome. Normal neurodevelopmental outcome was reported in 53.6% of fetuses. Subgroup analysis according to the location of ICH showed that PND occurred in 13.3% (95% CI, 5.7-23.4%) of fetuses with intra-axial bleeding and 26.7% (95% CI, 5.3-56.8%) of those with extra-axial bleeding. In fetuses with intra-axial hemorrhage, 25.2% (95% CI, 11.0-42.9%) required shunt placement or surgery after birth and 25.5% (95% CI, 15.3-37.2%) experienced cerebral palsy. In fetuses with intra-axial hemorrhage, mild and severe neurodevelopmental delay was observed in 14.9% (95% CI, 12.0-27.0%) and 32.8% (95% CI, 19.8-47.4%) of cases, respectively, while 53.2% (95% CI, 37.0-69.1%) experienced normal neurodevelopmental outcome. The incidence of mortality and postnatal neurodevelopmental outcome in fetuses with extra-axial hemorrhage could not be estimated reliably due to the small number of cases.

CONCLUSIONS

Fetuses with a prenatal diagnosis of ICH are at high risk of perinatal mortality and adverse neurodevelopmental outcome. Postnatal shunt placement or surgery was required in 28% of cases and cerebral palsy was diagnosed in approximately one-third of infants. Due to the rarity of ICH, multicenter prospective registries are warranted to collect high-quality data. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Diagnostic Value of Sylvian Fissure Hyperechogenicity in Fetal SAH

BACKGROUND AND PURPOSE

Fetal SAH is an intracranial malformation. The typical diagnostic features of fetal SAH in ultrasound have not been reported. This study aimed to evaluate the diagnostic value of Sylvian fissure hyperechogenicity by prenatal ultrasound in fetuses with SAH.

MATERIALS AND METHODS

The features on ultrasound and MR imaging of 10 fetuses with SAH were reviewed and summarized. The diagnostic value of the Sylvian fissure in fetal SAH by prenatal ultrasound was evaluated.

RESULTS

The typical and most obvious manifestations of SAH during the prenatal period were hyperechogenicity in the subarachnoid cavity, especially in the Sylvian fissure; all 10 cases (10/10) had such manifestations. Other manifestations included a hyperecho in other sulci (6/10), especially in the subfrontal sulcus, superior temporal sulcus, or parieto-occipital sulcus; a hyperecho in the cisterns (8/10), especially in the suprasellar cistern, posterior cranial fossa, cisterna ambiens, or quadrigeminal cistern; and a hyperecho around the anterior and posterior longitudinal fissures (2/10). Combined hemorrhage in the parenchymal layer or ventricles (9/10) was found. In addition, Doppler ultrasound showed that the peak flow velocity in the MCA increased in 6 cases (6/10).

CONCLUSIONS

The homogeneous hyperechogenicity of the Sylvian fissure is an important clue for detecting and diagnosing fetal SAH by prenatal ultrasound. A diagnostic approach has been proposed for fetal SAH, which has great significance in further prognosis.

Brain fetal neuroradiology: a beginner's guide

The importance of fetal magnetic resonance imaging (MRI) in the prenatal diagnosis of central nervous system (CNS) anomalies is rapidly increasing. Fetal MRI represents a third level examination usually performed, as early as 18-20 weeks of gestational age, when a second level (expert) neuro-ultrasonography (US) evaluation raises the suspicion of a CNS anomaly or when a genetic disorder is known. Compared to the US, MRI has the advantage to allow a better visualization and characterization of brain structures so to detect anomalies not visible in the US, thus resulting in relevant implications for parent counselling and pregnancy management. Moreover, the improvement of MRI technologies permits to obtain ultrafast sequences, which minimize the drawback of movement artifacts, and to perform advanced studies. This review aims at providing a practical guide for trainees and fellows who are approaching fetal MRI. In the first part, we provide information about indications, safety and protocols based on the state-of-the-art sequences, with a mention on the innovations related to the use of a 3T scanner. The second part is focused on the normal development of the human fetal brain related to its MR appearance, whose knowledge is essential to detect possible abnormalities. The last section briefly describes the most frequent abnormalities in the fetal brain and spine as depicted by MRI.

Blake's Pouch Cysts and Differential Diagnoses in Prenatal and Postnatal MRI : A Pictorial Review

PURPOSE

The clinical variability of Blake's pouch cysts (BPC) may range from asymptomatic via ataxia to sequelae of decompensated hydrocephalus. On the other hand, Dandy-Walker malformation (DWM) and cerebellar vermis hypoplasia generally correlate with less favorable neurologic development. The aim was to illustrate the potential of prenatal and postnatal neuroimaging to distinguish a BPC or persistent BP from other posterior fossa malformations.

METHODS

This pictorial review addresses the inconsistent nomenclature, clinical features, and magnetic resonance imaging (MRI) patterns of BPC and five differential diagnoses. The MRI findings of 11 patients, acquired at up to 3 T in 3 institutions, are demonstrated. Furthermore, the literature was searched for recent improvements in genetic and embryological background knowledge.

RESULTS

Posterior fossa malformations often resemble each other and may even be imitated by sequelae of hemorrhagic, ischemic or infectious disruptions, i.e. congenital anomalies of morphology despite normal developmental potential. Hydrocephalus is a typical, albeit not always congenital finding in BPC. It is frequently associated with cerebellar disruptions and DWM; however, it is also a rare complication of posterior fossa arachnoid cysts. A moderately elevated vermis needs follow-up to confirm persistent BP versus vermian hypoplasia or DWM. The fetal cerebellar tail, previously assumed to be specific for DWM, may be imitated in cases of persistent BP.

CONCLUSION

The accurate diagnosis of isolated BPC is not always straightforward, which is especially critical in the context of fetomaternal medicine. A detailed description of posterior fossa malformations is to be preferred over unspecific terminology.

Ultrasound of acquired posterior fossa abnormalities in the newborn

Neonatal brain sonography is part of routine clinical practice in neonatal intensive care units, but ultrasound imaging of the posterior fossa has gained increasing attention since the burden of perinatal acquired posterior fossa abnormalities and their impact on motor and cognitive neurodevelopmental outcome have been recognized. Although magnetic resonance imaging (MRI) is often superior, posterior fossa abnormalities can be suspected or detected by optimized cranial ultrasound (CUS) scans, which allow an early and bed-side diagnosis and monitoring through sequential scans over a long period of time. Different ultrasound appearances and injury patterns of posterior fossa abnormalities are described according to gestational age at birth and characteristics of the pathogenetic insult. The aim of this review article is to describe options to improve posterior fossa sequential CUS image quality, including the use of supplemental acoustic windows, to show standard views and normal ultrasound anatomy of the posterior fossa, and to describe the ultrasound characteristics of acquired posterior fossa lesions in preterm and term infants with effect on long-term outcome. The limitations and pitfalls of CUS and the role of MRI are discussed.

Outcome of Isolated Absent Septum Pellucidum Diagnosed by Fetal Magnetic Resonance Imaging (MRI) Scan

Improved fetal imaging has resulted in increased diagnosis of isolated absent septum pellucidum without other intracranial abnormalities. There is little literature regarding outcomes for these fetuses. This study hypothesized the majority of infants diagnosed by fetal magnetic resonance imaging (MRI) with isolated absent septum pellucidum would retain this diagnosis postnatally. Specifically, in the absence of postnatal endocrine or ophthalmologic abnormalities, postnatal imaging would find no additional related findings, and fetuses would be at low risk for developmental delay. Two of 8 subjects met postnatal criteria for septo-optic dysplasia; remaining subjects had normal postnatal endocrine and ophthalmologic evaluations and no significant related findings on postnatal MRI. One subject without septo-optic dysplasia had delays on developmental screening; all others had normal screening (range of follow-up 8-72 months). Our study questions the necessity of postnatal imaging for prenatally diagnosed isolated absent septum pellucidum. Majority of fetuses with isolated absent septum pellucidum retained this diagnosis postnatally.

Oxidative Stress as a Primary Risk Factor for Brain Damage in Preterm Newborns

The risk of oxidative stress is high in preterm newborns. Room air exposure of an organism primed to develop in a hypoxic environment, lacking antioxidant defenses, and subjected to hyperoxia, hypoxia, and ischemia challenges the newborn with oxidative stress production. Free radicals can be generated by a multitude of other mechanisms, such as glutamate excitotoxicity, excess free iron, inflammation, and immune reactions. Free radical-induced damage caused by oxidative stress appears to be the major candidate for the pathogenesis of most of the complications of prematurity, brain being especially at risk, with short to long-term consequences. We review the role of free radical oxidative damage to the newborn brain and propose a mechanism of oxidative injury, taking into consideration the particular maturation-dependent vulnerability of the oligodendrocyte precursors. Prompted by our observation of an increase in plasma Adenosine concentrations significantly associated with brain white matter lesions in some premature infants, we discuss a possible bioenergetics hypothesis, correlated to the oxidative challenge of the premature infant. We aim at explaining both the oxidative stress generation and the mechanism promoting the myelination disturbances. Being white matter abnormalities among the most common lesions of prematurity, the use of Adenosine as a biomarker of brain damage appears promising in order to design neuroprotective strategies.

Evaluation of the fetal cerebellum by magnetic resonance imaging

Obstetric protocols dictate that the fetal cerebellum should always be assessed during sonograms during pregnancy. For various reasons, including technical limitations or inconclusive sonographic findings, suspicion of cerebellar abnormalities is one of the most common indications for prenatal magnetic resonance imaging (MRI). Although sonography is the imaging technique of choice to assess the cerebellum, MRI shows the anatomy of the posterior fossa and abnormalities in the development of the fetal cerebellum in greater detail and thus enables a more accurate prenatal diagnosis. We describe and illustrate the normal anatomy of the fetal cerebellum on MRI as well as the different diseases that can affect its development. Moreover, we review the most appropriate terminology to define developmental abnormalities, their differential diagnoses, and the role of MRI in the prenatal evaluation of the posterior fossa.