Prenatal demonstration of afferent vessels and progressive thrombosis in a torcular malformation

To elucidate a part of the prenatal natural history of dural sinus malformation of the posterior fossa.

Ultrasound and magnetic resonance imaging were performed from 31 to 32 weeks' gestation.

We observed the progressive development of a thrombus that was visible as an expanding hyperechoic round area within a cystic mass of the posterior fossa. It was characterized, as expected for a vascular malformation, by the presence of blood flow into the aneurismal cavity. Color doppler identified superior sagittal and straight sinuses, and distinguished that their flow continued into the dilated torcular. Prenatal magnetic resonance imaging confirmed an arteriovenous malformation involving the dural sinus.

The vascular malformation had a fixed volume and preceded the thrombosis, which formed within several days. The present case is the first report with all the prenatal sonographic features of this condition.