Ultrasound Diagnosed Fetal Hydranencephaly in the Prenatal Period

Abstract

Abstract Hydranencephaly is a rare congenital encephalopathy characterized by a near complete absence of the cerebral cortical mantle and basal ganglia, with consequent replacement by cerebrospinal fluid (CSF). Although hydranencephaly is an extremely rare congenital entity with an incidence <1/10,000 live births, there are no known gender or racial predilections. However, polyhydramnios is a recognized association. Brain infarction from bilateral internal carotid artery occlusion, fetal hypoxia, leukomalacia, and congenital infections have all been implicated as possible etiologies for this rare entity. Ultrasonography can be used for prenatal diagnosis of fetal hydranencephaly, assessment for possible associations, and to exclude the common differential diagnoses. The objective of this report is to present an extremely rare congenital encephalopathy diagnosed in utero in a pregnant patient at the third trimester using ultrasonography, to review pertinent literature about this condition, and to highlight the role of ultrasonography in making a diagnosis of hydranencephaly while excluding common differential diagnoses. This was a case of hydranencephaly diagnosed at the third trimester of gestation, precisely at 36 weeks (with a discrepancy in the sonographically estimated average fetal gestational age which was about 33 weeks) at the time of diagnosis in a Nigerian tertiary health facility. Sonography revealed a disproportionately large fetal cranium relative to other fetal parts, the absence of a large proportion of the cerebral cortical mantle, and its replacement with anechoic CSF. The falx cerebri was preserved. Hydranencephaly is a rare congenital entity. Its diagnosis can be unraveled in the prenatal period with the use of ultrasonography particularly in resource-poor centers in sub-Saharan Africa where advanced imaging modalities such as magnetic resonance imaging are not readily available.