[A case of venous thrombosis associated with medullary venous malformation].

A 16 year-old girl was admitted to our hospital complaining of headache and vomiting. She was born with an orbital lymphangioma, which was resected partially at a younger age. On admission she had mild confusion and light neck stiffness as neurological positive findings. Enhanced CT scan showed an eight-figure enhancement at the straight sinus and a linear enhancement at the vermis. Angiography showed venous thrombosis spreading in the deep cerebral veins and the right superior ophthalmic vein. Furthermore a medullary venous malformation (MVM) was disclosed in the posterior fossa. Administration of urokinase and glycerol relieved her symptoms gradually. After that treatment, partial recanalization of the deep cerebral veins and the straight sinus and disappearance of the MVM were recognized in the second angiography. In the present case, the MVM played an important role as collateral channel. But, in general, when venous thrombosis occurs, collateral circulation is maintained by cork-screw vessels, not by MVM. In the light of the presence of the lymphangioma, the present case was thought to be a rare condition in the venous system. It appears that residual fetal vessels have existed in the posterior fossa from birth. It is considered that the residual fetal vessels opened and dilated temporally and were recognized as an MVM in angiography, when cerebral venous flow was disturbed by the venous thrombosis.