Cavum veli interpositi cyst: prenatal diagnosis and postnatal outcome

Abstract

The cavum veli interpositi (CVI) is a space within the double-layered tela choroidea of the third ventricle. Occasionally, this space is fluid-filled and sonographically visible as an interhemispheric anechoic cyst. Because of its rarity, the incidence of CVI cyst is undetermined and the outcome of affected individuals has been found to be variable. The aim of this study was to report our experience of the sonographic findings and outcome of fetuses affected by CVI cysts. In five fetuses with a CVI cyst, we performed targeted prenatal ultrasound scans of intracranial structures and a detailed anatomical survey to rule out associated malformations. Follow-up consisted of neurological examination and neurosonography. The CVI cyst appeared as a well-defined anechoic lesion without adjacent mass effect. In all fetuses the cyst was single and in two cases it enlarged slightly during pregnancy. The cyst was isolated in three fetuses and associated with borderline ventriculomegaly in two. A single umbilical artery was the only associated extracranial anomaly and this was detected in only one fetus. Neurosonography confirmed the presence of CVI cysts in all cases after delivery. During postnatal follow-up (range 10-48 months), the cyst regressed in one case within 1 month after delivery while the size of the others remained stable. No infant developed psychomotor disorders. Prenatal sonographic diagnosis of CVI cysts is feasible. Its finding in isolation is consistent with favorable postnatal outcome.