Prenatal diagnosis of cavum velum interpositum cysts: significance and outcome.

Objectives: To describe a fetal cavum velum interpositum cyst (CVIC) and to review its clinical significance.

Methods: Description and follow-up of two cases with prenatal diagnosis of a midline cyst in the fetal brain, at the Chaim Sheba Medical Center. The cases were reviewed and followed-up by a multidisciplinary team that included sonographers, pediatric neurologists, pediatric neurosurgeons, radiologists, and clinical geneticists. Medline search of cases of cysts of the cavum velum interpositum as reported in the English literature.

Results: Two patients referred for consultation owing to midline cysts were diagnosed with isolated cysts of the cavum velum interpositum without other anomalies. Magnetic resonance imaging (MRI) of the fetal brain did not reveal any additional malformations in either case. Prenatal follow-up showed the cysts to be stable in one case and decreased in size in the other. Postnatal neurodevelopmental outcome to date is normal. (Range of follow-up: 6-24 months.) Eight cases reported in the literature as CVIC resulted in favorable prognosis in all without further intervention. However, one infant required ventriculoperitoneal shunting due to progressive hydrocephalus, but developed normally nonetheless.

Conclusion: Prenatal diagnosis of cysts of the cavum velum interpositum, which are isolated, single, stable in size, and not associated with other anomalies, is consistent with a favorable postnatal outcome.