Fetal magnetic resonance imaging in the prenatal diagnosis of cerebellar hemorrhage

Prenatal diagnosis of cerebellar hemorrhage: A case report

We report the case of a fetus with a sonographic diagnosis of hyperechogenic cerebellum at 28 weeks' gestation, which was suspected to be of hemorrhagic origin on fetal ultrasound. As an adjunct to ultrasound, fetal MRI can confirm the hemorrhagic origin of hyperechogenic cerebellar lesions, particularly by showing a high signal on T1-weighted images. No etiological factors for fetal hemorrhage were found other than maternal hypertension and aspirin use. Postnatal MRI confirmed the prenatal diagnosis of cerebellar hemorrhage without underlying vascular anomaly.

Fetal subdural hematoma with favorable neonatal outcome: A case report

Fetal subdural hematoma is a rare diagnosis. Identification of risk factors, timely diagnosis, and delivery can optimize neonatal outcome of this fetal condition with poor prognosis.

Prenatal Cerebellar Disruptions: Neuroimaging Spectrum of Findings in Correlation with Likely Mechanisms and Etiologies of Injury

There is increasing evidence that the cerebellum is susceptible to prenatal infections and hemorrhages and that congenital morphologic anomalies of the cerebellum may be caused by disruptive (acquired) causes. Starting from the neuroimaging pattern, this report describes a spectrum of prenatal cerebellar disruptions including cerebellar agenesis, unilateral cerebellar hypoplasia, cerebellar cleft, global cerebellar hypoplasia, and vanishing cerebellum in Chiari type II malformation. The neuroimaging findings, possible causative disruptive events, and clinical features of each disruption are discussed. Recognition of cerebellar disruptions and their differentiation from cerebellar malformations is important in terms of diagnosis, prognosis, and genetic counselling.

Cerebellar disruptions and neurodevelopmental disabilities

The vulnerability of the cerebellum during prenatal life to disruptive events such as hemorrhage and infection leads to a wide variety of morphological abnormalities. This review discusses various prenatal cerebellar disruptions including cerebellar agenesis, unilateral cerebellar hypoplasia, cerebellar cleft, global cerebellar hypoplasia, and vanishing cerebellum in Chiari type II malformation. For each entity, we discuss the definition, potential pathomechanism, clinical findings including neurocognitive and behavioral problems, neuroimaging features, and management. Accurate recognition of cerebellar disruptions and their differentiation from malformations is important in terms of diagnosis, prognosis, and genetic counselling.

"Acquired" Dandy-Walker malformation and cerebellar hemorrhage: Usefulness of serial MRI

BACKGROUND/PURPOSE

Neuroimaging plays a fundamental role in the diagnosis of Dandy Walker malformation (DWM), a posterior fossa anomaly that is usually associated with genetic abnormalities, but may rarely be ascribed to acquired causes. Here, we report the clinical history and neuroimaging studies of a child with a complex cardiac malformation, developmental delay, and oculomotor anomalies whose neuroimaging findings were consistent with an acquired form of DWM.

METHODS/RESULTS

Fetal MRI at gestational weeks 27 and 31 showed cerebellar and vermis hypoplasia and fourth ventricle enlargement, together with hemosiderin deposits on the cerebellar hemispheric surface, but without significant vermian rotation. Postnatal MRIs at 5 days and 13 months revealed progressive counter-clockwise rotation of the hypoplastic cerebellar vermis with cystic dilation of the fourth ventricle, eventually leading to a full-blown DWM.

CONCLUSION

This case strengthens the opinion that DWM is a heterogeneous condition, and may support the hypothesis that acquired meningeal abnormalities in the form of cortico-pial hemosiderosis may play a role in the development of DWM. This case also demonstrates that serial neuroimaging plays a key role in the correct diagnosis of posterior fossa malformations, whose prognosis is difficult to establish on second trimester fetal MRI and requires longer clinical follow-up.

Prenatal MR imaging features of isolated cerebellar haemorrhagic lesions

OBJECTIVE

Prenatal features of isolated cerebellar haemorrhagic lesions have not been sufficiently characterised. We aimed to better define their MR imaging characteristics, documenting the location, extension, evolution stage and anatomic sequelae, and to better understand cerebellar haemorrhage pathophysiology.

MATERIALS AND METHODS

We screened our foetal MR imaging database (3200 cases) for reports of haemorrhagic lesions affecting only the cerebellum (without any supratentorial bleeding or other clastic lesions), defined as one of the following: T2-weighted hypointense or mixed hypo-/hyperintense signal; rim of T2-weighted hypointense signal covering the surface of volume-reduced parenchyma; T1-weighted hyperintense signal; increased DWI signal.

RESULTS

Seventeen cases corresponded to the selection criteria. All lesions occurred before the 26th week of gestation, with prevalent origin from the peripheral-caudal portion of the hemispheres and equal frequency of unilateral/bilateral involvement. The caudal vermis appeared affected in 2/3 of cases, not in all cases confirmed postnatally. Lesions evolved towards malformed cerebellar foliation. The aetiology and pathophysiology were unknown, although in a subset of cases intra- and extracranial venous engorgement seemed to play a key role.

CONCLUSIONS

Onset from the peripheral and caudal portion of the hemispheres seems characteristic of prenatal cerebellar haemorrhagic lesions. Elective involvement of the peripheral germinal matrix is hypothesised.

KEY POINTS

• The cerebellum can be vulnerable to bleeding during foetal development. • Isolated cerebellar haemorrhages can be seen on prenatal MRI. • In our cohort, isolated foetal cerebellar haemorrhages occurred before the 26th gestational week. • Haemorrhagic lesions happening in utero could look like malformations on post-natal MRI. • Venous engorgement could have a role in causing cerebellar haemorrhagic lesions.

Prenatal cerebellar hemorrhage: fetal and postnatal neuroimaging findings and postnatal outcome

BACKGROUND

Despite significant progress in fetal neuroimaging techniques, only a few well-documented examples of prenatal cerebellar hemorrhages are available in the literature. In the majority of these individuals, the diagnosis of prenatal cerebellar hemorrhages led to termination of pregnancy or death occurred in utero; data about postnatal outcome of children with prenatal diagnosis of cerebellar hemorrhages are scant. We describe fetal and postnatal neuroimaging findings and the neurodevelopmental outcome of a child with a large cerebellar hemorrhage that occurred at approximately 27 weeks' gestation.

METHOD

Data about neurological features and neurodevelopmental outcome were collected from the clinical history and follow-up examination. All pre- and postnatal MRI data were qualitatively evaluated for infra- and supratentorial abnormalities.

RESULTS

Fetal MRI at 27 weeks' gestation showed a T1-hyperintense and T2-hypointense lesion within the cerebellum suggestive of bilateral cerebellar hemorrhages with extension into the adjacent subarachnoid, subdural, and intraventricular spaces. The prenatal cerebellar hemorrhage was possibly related to maternal sepsis. Postnatal MRI showed encephalomalacic changes involving the vermis and both cerebellar hemispheres. Neurodevelopmental follow-up at 15 months of age was concerning for global developmental delay and significant right esotropia.

CONCLUSION

This child illustrates (1) the role of prenatal neuroimaging in the diagnosis of fetal cerebellar hemorrhages, (2) the significance of cerebellar involvement for neurodevelopment, and (3) the importance of the collection of postnatal outcome data in children with prenatal diagnosis of cerebellar hemorrhage.

Prenatal unilateral cerebellar hypoplasia in a series of 26 cases: significance and implications for prenatal diagnosis

OBJECTIVE

To define imaging patterns of unilateral cerebellar hypoplasia (UCH), discuss possible pathophysiological mechanisms and underline the etiology and prognosis associated with these lesions.

METHODS

In this retrospective study we reviewed the charts of 26 fetuses diagnosed between 2003 and 2011 with UCH, defined by asymmetrical cerebellar hemispheres with or without decreased transverse cerebellar diameter. The review included analysis of the anatomy of the cerebellar hemispheres, including foliation, borders and parenchymal echogenicity, and of the severity of the hypoplasia. Data from clinical and biological work-up and follow-up were obtained.

RESULTS

Our series could be divided into two groups according to whether imaging features changed progressively or remained constant during follow-up. In Group 1 (n = 8), the progression of imaging features, echogenic cerebellar changes and/or hyposignal in T2*-weighted MR images were highly suggestive of ischemic/hemorrhagic insult. In Group 2 (n = 18), imaging features remained constant during follow-up; UCH was associated with abnormal foliation in three proven cases of clastic lesions, a cystic lesion was noted in three cases of PHACE (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac abnormalities/aortic coarctation, eye abnormalities) syndrome and, in the remaining cases, UCH remained unchanged, with no imaging pattern typical of hemorrhage. In 24 cases the infant was liveborn and follow-up was continued in 23, for a mean period of 3 years. Among these, neurological complications were identified in seven (in one of seven (at a mean of 46 months) in Group 1 and in six of 16 (at a mean of 35 months) in Group 2). The surface loss of cerebellar hemisphere was > 50% in 19/24 fetuses and the vermis was clearly normal in appearance in 19/24. Predisposing factors for fetal vascular insult were identified in eight cases: these included maternal alcohol addiction, diabetes mellitus, congenital cytomegalovirus infection and pathological placenta with thrombotic vasculopathy and infarctions.

CONCLUSION

UCH is defined as a focal lesion of the cerebellum that may be secondary to hemorrhage and/or ischemic insult, suggesting a clastic origin, particularly when imaging follow-up reveals changes over time. UCH may also be a clue for the prenatal diagnosis of PHACE syndrome. The amount of surface loss of cerebellar hemisphere does not correlate with poor prognosis. UCH with normal vermis is often associated with normal outcome.

Cerebellar hemorrhage in very low birth weight premature infants: the advantage of the posterolateral fontanelle view

OBJECTIVE

The purpose of this study was to determine the prevalence of cerebellar hemorrhage in very low birth weight infants using the posterolateral fontanelle for ultrasound (US) examination.

METHODS

The study included 125 very low birth weight premature infants (defined as equal or less than 1500 grams at birth) hospitalized in the premature or neonatal intensive care departments that had at least one head US examination including both anterior and posterolateral fontanelle scans.

RESULTS

On US performed through the posterolateral fontanelle, four (3.2%) infants had echogenic posterior fossa lesions interpreted as hemorrhages. None of these lesions were initially or retrospectively observed through the standard anterior fontanelle scan. Two infants died at age 4 and 39 days, respectively. All survivors are being followed up in the hospital's neurodevelopment outpatient clinic.

CONCLUSIONS

Cerebellar hemorrhage may be overlooked on standard anterior fontanelle views. The posterolateral approach may assist in diagnosing these lesions.

Prenatal stroke

The main focus of this chapter is the comprehensive description of the neuropathology, the imaging correlates and underlying mechanisms of prenatal stroke. We describe established prenatal stroke in subgroups similar to postnatal stroke: arterial (forebrain or hindbrain) infarction, venous thrombosis, primary lobar haemorrhage. This longitudinal classification should facilitate the study of risk factors and mechanisms. Forebrain lesions of arterial type present as porencephaly, (hemi)hydranencephaly, multicystic encephalopathy or schizencephaly. Venous prenatal forebrain stroke presents as simple porencephaly (in some of genetic nature) and sinus thrombosis. A list of rare porencephaly-like conditions is added for differentiation from arterial and venous porencephaly. Hindbrain infarctions (so far the only reported variants seem to be of arterial nature) present as brainstem disconnection, focal brainstem destruction, uni- or bilateral cerebellar destruction and focal spinal cord ischaemia. Prenatal intracranial haemorrhage and congenital brain infection should be considered in the differential diagnosis of prenatal stroke.

Morphological spectrum of prenatal cerebellar disruptions

There is increasing evidence that the cerebellum is susceptible to both prenatal infections and haemorrhages as well as being vulnerable in extremely preterm babies, but not to perinatal and postnatal hypoxic-ischaemic injuries. Starting with the imaging appearance we describe and illustrate a spectrum of prenatal cerebellar disruptions: cerebellar agenesis; unilateral cerebellar hypoplasia; unilateral cerebellar cleft; global cerebellar hypoplasia; vanishing cerebellum in myelomeningocele; and disruption of cerebellar development in preterm infants. We discuss neuroradiological characteristics, possible disruptive events, and clinical findings in the different morphological patterns. Remarkably, the same disruptive agent can cause different neuroradiological patterns, which appear likely to represent a morphological spectrum. The analysis of imaging patterns is crucial in recognising cerebellar disruptions. Recognition of cerebellar disruptions and their differentiation from cerebellar malformations is important in terms of diagnosis, prognosis, and genetic counselling.

How accurately does current fetal imaging identify posterior fossa anomalies?

OBJECTIVE

The first objective of our study was to describe the prevalence and spectrum of posterior fossa anomalies over 5 years in a major fetal care center where the referral diagnosis (by fetal sonography) was investigated by fetal MRI and, if confirmed, by postnatal MRI if possible. The second objective was to assess the accuracy with which fetal MRI predicts postnatal MRI findings in this population.

MATERIALS AND METHODS

We retrospectively identified all cases of suspected fetal posterior fossa anomalies referred to our center from 2002 through 2006. We reviewed maternal, fetal, neonatal, and follow-up records of all cases and fetal and early postnatal imaging studies.

RESULTS

Of the 90 cases of suspected fetal posterior fossa anomalies (by fetal sonography) referred over the study period, 60 (67%) were confirmed by fetal MRI. Of 42 live-born infants, 39 (93%) underwent postnatal MRI. There was complete agreement in fetal and postnatal MRI diagnoses in 23 infants (59%). In 16 cases (41%), fetal and postnatal MRI diagnoses disagreed; postnatal MRI excluded fetal MRI diagnoses in six cases (15%) and revealed additional anomalies in 10 cases (26%).

CONCLUSION

Although a valuable adjunct to fetal sonography in cases of suspected posterior fossa anomaly, current fetal MRI, particularly in early gestation, has limitations in accurately predicting postnatal MRI abnormalities. Advancing the accuracy of MRI for the diagnosis of posterior fossa anomalies will require greater understanding of normal brain development and improved tissue resolution of fetal MRI. During the interim, our findings strongly support the need for postnatal MRI follow-up in cases with suspected posterior fossa anomalies by fetal MRI.

Fetal MR Imaging

Ultrasonography is the primary prenatal screening modality used in the evaluation of the fetus and the maternal pelvis. However, fetal MR imaging plays a complementary role to prenatal ultrasound in the evaluation of the fetus with suspected abnormalities. MR imaging's role includes confirming or excluding possible lesions, defining their full extent, aiding in their characterization, and demonstrating other associated abnormalities. As newer techniques such as diffusion imaging, MR spectroscopy, and functional studies are used more widely, it is hoped that additional information will be made available by this modality to physicians evaluating and taking care of fetuses.

Fatal outcome following foetal cerebellar haemorrhage associated with placental thrombosis

Cerebellar haemorrhage is a rare prenatal event. Possible aetiologies for foetal intracranial haemorrhage include: trauma, asphyxia, infection, vascular defects, blood dyscrasias, ingestion of drugs and alloimmune and isoimmune thrombocytopenia. We report the ultrasonographic diagnosis of a cerebellar haematoma at 21 weeks of gestation. The foetus succumbed at 33 weeks of gestation following rupture of a subcapsular liver haematoma. An autopsy demonstrated a placental foetal thrombotic vasculopathy and thrombi in the chorionic vessels. We assume that hypercoagulability was responsible for the multiple infarcts in the foetus with haemorrhagic transformation in the cerebellum and liver. The differential diagnosis of foetal cerebellar haemorrhage includes maternal hypercoagulability; in this case multiple haemorrhagic/ischaemic events may be encountered during the pregnancy. A thorough investigation to elucidate the aetiology is pertinent in every case of foetal cerebellar haemorrhage in order to enable accurate counselling and correct management.