Prevalence of ventriculomegaly in association with myelomeningocele: correlation with gestational age and severity of posterior fossa deformity.

ABSTRACT

PURPOSE: To investigate the relationship of ventriculomegaly (VM) with gestational age (GA) and the severity of the associated Chiari II malformation. MATERIALS AND METHODS: The sonograms of 51 fetuses with myelomeningoceles were retrospectively reviewed. VM was judged to be present when the transverse ventricular atrial diameter was greater than 10 mm. The severity of the posterior fossa (PF) deformity was subjectively graded as mild, moderate, or severe. Thirty-four fetuses were scanned at < or = 24 weeks GA, and 17 were scanned at > 24 weeks GA. RESULTS: The prevalence of VM was 61%. However, only 44% of fetuses < or = 24 weeks GA had VM, whereas 94% of fetuses > 24 weeks GA had VM. When compared with fetuses with mild PF deformities, fetuses with moderate or severe deformities had a higher prevalence of VM and the largest ventricles. CONCLUSION: The prevalence of VM in fetuses with myelomeningoceles varies with both GA and the severity of the associated PF deformity. These observations may provide additional prognostic information once a myelomeningocele is detected at sonography.