Extrasinusal Dural Arteriovenous Malformation Misdiagnosed as Intraorbital Tumor

ABSTRACT

Dural arteriovenous malformations are rare, accounting for 10-15% of all intracranial arteriovenous malformation and are thought to be acquired lesion caused by dural sinus thrombosis. The authors report a rare case of extrasinusal dural arteriovenous fistula in the right middle fossa adjacent to the superior orbital fissure. During the preceding 17 years, this 31-year-old female had complained of proptosis and ocular pain in the right eye. Computed tomography and magnetic resonance imaging showed a retrobular intraconal mass in the right orbit; Angiography revealed an extrasinusal dural arteriovenous fistula in the right middle fossa adjacent to the superior orbital fissure, which drains into the superior ophthalmic and inferior temporal vein. After embolization of the fistula by injection of N-butylcyanoacrylate(NBCA), we intended to remove the retrobulbar intraconal mass seen on CT and MRI by means of a unilateral partial orbitotomy on the supraorbital rim and orbital roof, and to this end, explored the right orbit. We were unable, however, to locate any mass lesion in the orbital cavity, and postoperative CT and MRI showed no such lesion. We were of the opinion that the mass shown on preoperative CT and MRI was a dilated intraorbital vein structure which disappeared after embolization, operative ligation and cutting of the dural arterivenous fistula. Finally, proptosis and ocular pain disappeared, and the patient recovered with any no neurologic deficit.