Malformations of the fetal dural sinuses.

BACKGROUND: Dural sinus malformation (DSM) is a term used to describe congenital vascular malformations characterized by massive dilation of one or more dural sinuses: these dilatations are typically associated with arteriovenous shunts. Such malformations can present antenatally but their early natural history and anatomy is poorly defined.
METHODS: We reviewed five years of autopsy experience and retrieved three primary vascular malformations of the fetal dural sinuses with ultrasound, magnetic resonance imaging (MRI) and post-mortem correlation.
RESULTS: Fetal ultrasound and MRI obtained between 19 and 23 weeks gestational age demonstrated in all cases dilation of the dural sinuses. In two cases vascular thromboses were present in either the dilated dural sinus (one of three) or the associated arteriovenous fistula (one of three). All cases were autopsied at 22-23 weeks gestational age. In one there was imaging and autopsy evidence of remodeling of the dural sinuses associated with a pial arteriovenous fistula. In two cases, no arteriovenous malformation was identified on initial imaging, but only became evident at autopsy. One case showed morphological overlap with vein of Galen aneurysmal malformation, with a midline arteriovenous shunt and vein of Galen ectasia. The other demonstrated a perisylvian dural arteriovenous fistula.
CONCLUSION: In utero thrombosis of feeding vascular malformations or of the dural sinus malformation may be prominent. The early in utero developmental trajectory of dural sinus malformation (DSM) is poorly defined and deserves further study.