Objective: Advances in fetal magnetic resonance imaging allow the detection of subtle anatomic anomalies of unclear long-term clinical significance. The purpose of this study was to examine the accuracy of fetal magnetic resonance imaging in the diagnosis of isolated inferior vermian hypoplasia and to describe the neurodevelopmental outcome.
Study design: We reviewed all cases with fetal and postnatal magnetic resonance imaging studies between 1999 and 2003 and identified 19 cases with a diagnosis of isolated inferior vermian hypoplasia. We compared prenatal and postnatal magnetic resonance imaging studies and evaluated subjects using developmental scales.
Results: Isolated inferior vermian hypoplasia was confirmed by postnatal magnetic resonance imaging in 68% of the patients (13/19); the remaining 6 patients had normal postnatal magnetic resonance imaging results. On developmental testing at mean age 19.8 +/- 4.9 months, 3 infants (23%) with confirmed postnatal diagnosis demonstrated motor and language delays and functional difficulties, and 2 infants (15%) had behavioral problems; none of the infants with normal postnatal magnetic resonance imaging studies were delayed.
Conclusion: Isolated inferior vermian hypoplasia in the second trimester may be over-diagnosed by fetal magnetic resonance imaging and therefore warrants postnatal magnetic resonance imaging confirmation.