Torcular herophili venous malformation diagnosed by ultrasound and followed up by fetal MRI

A dramatically expansive vascular mass occupying about half of the skull volume was detected by the use of ultrasound in the posterior cerebral fossa of a 22-week fetus. We performed a fetal MRI confirming the presence of a massive extraparenchymal lesion in the region of confluence of the venous sinuses. It was isointense to the cortex in T1 and T2 with ipointense components in T2 and iperintense in T1. No signal alteration was detected within cerebellar and cerebral hemispheres. The silvian region presented two dilated venous vessels. The final diagnosis was dural sinuses malformation of the torcular Herophili. Serial MRI scans were performed: at 26 weeks we noted an increase in size, afterwards the mass shrank progressively at 31 and 37 weeks. The macrocephalic fetus was delivered at 38 weeks by elective Cesarean section and neither neurological sequelae nor cardiac failure were present at birth. At the first MRI scan 24 hours after birth the lesion was unchanged and the signal was consistent with partial thrombosis. The transverse sinuses and the posterior portion of the superior sagittal sinus, in the peripheral region of the venous lake, could not be demonstrated by venous angiographic MRI, as well as the left jugular vein. No suggestive signs for a clear arterial-venous shunt were identified by the use of arterial angiographic MRI. The lesion reduced in size progressively in the following two months and a better depiction of transverse sinuses and jugular veins was obtained. The arterial angiographic MRI study at two months of age detected arterial-venous shunts arising from the mean meningeal artery and right carotid artery meeting the region of the torcular Herophili. At 6 months of age the shunts were less evident and the mass was further decreased. The infant is currently two years of age and in good condition. No treatment was performed at present due to the further decrease in size of the lesion and to the absence of neurological signs and symptoms.