Fowler syndrome and fetal MRI findings: a genetic disorder mimicking hydranencephaly/hydrocephalus

Fetal ventriculomegaly is a common referral for prenatal MRI, with possible etiologies being hydrocephalus and hydranencephaly. The underlying cause of hydranencephaly is unknown, but many have suggested that the characteristic supratentorial injury is related to idiopathic bilateral occlusions of the internal carotid arteries from an acquired or destructive event. Fowler syndrome is a rare genetic disorder that causes fetal akinesia and a proliferative vasculopathy that can result in an apparent hydranencephaly–hydrocephaly complex. On prenatal imaging, the presence of significant parenchymal loss in the supratentorial and infratentorial brain is a clue to the diagnosis, which should prompt early genetic testing.