Fetal presentation of PHACES syndrome

Fetal neuroimaging findings in PHACE syndrome: case report and review of the literature

OBJECTIVE

To describe the main prenatal sonographic and magnetic resonance imaging (MRI) features leading to the diagnosis of Posterior fossa malformations, Hemangiomas of the face, Arterial anomalies, Coarctation of the aorta and cardiac defects, and Eye abnormalities (PHACE) syndrome. The literature was also reviewed in order to determine the main neuroimaging features of fetuses with this condition.

RESULTS

The index case was referred at 24 weeks' gestation with the probable diagnosis of Dandy-Walker malformation. Prenatal sonographic examination revealed hypoplasia of the left cerebellar hemisphere, hypoplasia of the cerebellar vermis, and enlarged cisterna magna (the "tilted telephone receiver sign"). Fetal MRI at 30 weeks confirmed the findings and also revealed an ipsilateral retrocerebellar cyst communicating with the asymmetrical dilated fourth ventricle, upward displacement of the left cerebellar hemisphere, and elevation of the ipsilateral tentorium. Postnatally, a large left facial segmental hemangioma as well as ipsilateral vascular intracranial malformations were identified, confirming the diagnosis of PHACE syndrome. A review of the literature revealed 11 reports describing 22 fetuses with prenatal imaging studies, including ours, confirming the high prevalence of specific posterior fossa abnormalities associated with PHACE syndrome.

CONCLUSION

Our case and those reported in the literature support the observation that PHACE syndrome presents with characteristic features affecting the posterior fossa, which can be identified through prenatal sonography and fetal MRI.

Diagnostic imaging of posterior fossa anomalies in the fetus

Ultrasound and magnetic resonance imaging are the two imaging modalities used in the assessment of the fetus. Ultrasound is the primary imaging modality, whereas magnetic resonance is used in cases of diagnostic uncertainty. Both techniques have advantages and disadvantages and therefore they are complementary. Standard axial ultrasound views of the posterior fossa are used for routine scanning for fetal anomalies, with additional orthogonal views directly and indirectly obtainable using three-dimensional ultrasound techniques. Magnetic resonance imaging allows not only direct orthogonal imaging planes, but also tissue characterization, for example to search for blood breakdown products. We review the nomenclature of several posterior fossa anomalies using standardized criteria, and we review cerebellar abnormalities based on an etiologic classification.

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.

In utero diagnosis of PHACE syndrome by fetal magnetic resonance imaging (MRI)

The acronym PHACE describes the association of facial hemangioma with anomalies of the posterior fossa, cerebral arteries, and cardiovascular and ocular alterations. This study presents a case of diagnostic suspicion based on fetal MRI. We report the case of a pregnant woman whose 26-week MRI revealed a female fetus with hypoplasia of the right cerebellar hemisphere and right microphthalmia, leading to the suspicion of PHACE syndrome. The diagnosis was confirmed at birth, together with other criteria: facial hemangioma, absent posterior inferior cerebellar artery, and dysplasia of the right internal carotid artery. To our knowledge, this is the first live case described prenatally with both ocular and cerebellar findings on fetal MRI that suggest PHACE syndrome. The prenatal presence of 2 PHACE criteria led to the suspicion of this syndrome, and prenatal diagnostic criteria might be developed to improve information regarding the prognosis of cerebellar malformations.

Segmental Neurovascular Syndromes in Children

The concept of segmental vascular syndromes with different, seemingly unrelated, diseases is based on the embryology of the neural crest and the mesoderm migration of cells that share the same metameric origin. Migrating patterns of these cells link the brain, the cranial bones, and the face on the same side. A somatic mutation developing in the region of the neural crest or the adjacent cephalic mesoderm before migration can, therefore, be postulated to produce arterial or venous metameric syndromes, including PHACES, CAMS, Cobb syndrome, and Sturge-Weber syndrome. Although these diseases may be rare, their relationships among each other and their postulated linkage with the development of the neural crest and the cephalic mesoderm may shed light on the complex pathology and etiology of various cerebral vascular disorders.