Hippocampal rotation is associated with ventricular atrial size

Background Fetal ventriculomegaly is a source of apprehension for expectant parents and may present prognostic uncertainty for physicians. Accurate prenatal counseling requires knowledge of its cause and associated findings as the differential diagnosis is broad. We have observed an association between ventriculomegaly and incomplete hippocampal inversion. Objective To determine whether ventricular size is related to incomplete hippocampal inversion. Materials and methods We retrospectively evaluated pre- and postnatal brain MRIs in normal subjects (mean GA, 31 weeks; mean postnatal age, 27 days) and patients with isolated ventriculomegaly (mean GA, 31 weeks; mean postnatal age, 68 days) at a single academic medical center. Lateral ventricular diameter, multiple qualitative and quantitative markers of hippocampal inversion, and evidence of intraventricular hemorrhage were documented. Results Incomplete hippocampal inversion and ventricular size were associated in both normal subjects ( n =51) and patients with ventriculomegaly ( n =32) ( P