Fig. 1

Progressive obliteration of the aqueduct of Sylvius (SA) in hydrocephalus. a An ultrasound of the fetal patient at 36 GW demonstrating dilation of the lateral ventricles (arrows). b MRI at 33 GW. The third ventricle (3°) and posterior horns of the lateral ventricles (ph) are dilated. c MRI at 33 weeks. Stenosis of the SA is shown. d Detailed magnification of the area framed in C showing stenosis of the SA. 4°, fourth ventricle. e CT at 39 GW (or the 2nd PN day). The lateral (LV) and third (3°) ventricles are dilated. f MRI of the brain on the 5th postnatal day, sagittal T2 imaging. The SA is obliterated