An atypical case of dural sinus malformation

Female, 29

Atypical Fetal dural venous sinus ectasia with thrombosis

Case of a 32 week old fetus of a 29 year old woman, that was incidentally found to have a cerebral space occupying lesion on a routine second trimester ultrasound, suspicious for dural venous sinus ectasia with thrombosis (DVSET). The US findings required confirmatory MR imaging for definite diagnosis and better delineation.

Initial sonographic images showed an intracranial, posterior, space occupying lesion showing blood flow on doppler images, suggestive of posterior dural venous sinus malformation. US also revealed a suspected thrombosis in the vicinity of the confluence of sinuses (torcular Herophili). MR images showed a large stratified, iso and hypointense thrombus (suggestive of different ages) in a dilated torcular Herophili, extending into the superior sagittal sinus with sparing of the transverse sinus. No obvious arteriovenous malformation could be detected. Findings were consisted with atypical posterior DVSET.

For the pathophysiology of DVSET, arteriovenous fistulas secondary or contributing to the formation of the venous ectasia is one of the pathophysiological hypotheses. However, MR angiography generally do not show an obvious arteriovenous malformation. Regarding DVSET prognosis, spontaneous progressive thrombosis and regression of the intravascular component of the venous sinus ectasia is considered the natural progression of DVSET.

DVSET can occur antenatally and could be first suspected by fetal real-time and color Doppler ultrasound examination and later confirmed with MR images. Radiologists should know the sonographic signs of dural sinus malformation in addition to the typical and atypical subtypes for proper diagnosis.