Congenital aqueductal stenosis

Sagittal (A) and axial (B) T1-weighted MR images of a term neonate with hydrocephalus due to congenital aqueductal stenosis. The infant was noted to have ventriculomegaly on prenatal ultrasound. Postnatal MRI showed focal stenosis in the midportion of the cerebral aqueduct (arrow) with associated dilation of the lateral and third ventricles.