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.