Noncavernous arteriovenous shunts mimicking carotid cavernous fistulae

PURPOSE The classic symptoms and signs of carotid cavernous sinus fistula or cavernous sinus dural arteriovenous fistula (AVF) consist of eye redness, exophthalmos, and gaze abnormality. The angiography findings typically consist of arteriovenous shunt at cavernous sinus with ophthalmic venous drainage with or without cortical venous reflux. In rare circumstances, the shunts are localized outside the cavernous sinus, but mimic symptoms and radiography of the cavernous shunt. We would like to present the other locations of the arteriovenous shunt, which mimic the clinical presentation of carotid cavernous fistulae, and analyze venous drainages. METHODS We retrospectively examined the records of 350 patients who were given provisional diagnoses of carotid cavernous sinus fistulae or cavernous sinus dural AVF in the division of Interventional Neuroradiology, Ramathibodi Hospital, Bangkok between 2008 and 2014. Any patient with cavernous arteriovenous shunt was excluded. RESULTS Of those 350 patients, 10 patients (2.85%) were identified as having noncavernous sinus AVF. The angiographic diagnoses consisted of three anterior condylar (hypoglossal) dural AVF, two traumatic middle meningeal AVF, one lesser sphenoid wing dural AVF, one vertebro-vertebral fistula (VVF), one intraorbital AVF, one direct dural artery to cortical vein dural AVF, and one transverse-sigmoid dural AVF. Six cases (60%) were found to have venous efferent obstruction. CONCLUSION Arteriovenous shunts mimicking the cavernous AVF are rare, with a prevalence of only 2.85% in this series. The clinical presentation mainly depends on venous outflow. The venous outlet of the arteriovenous shunts is influenced by venous afferent-efferent patterns according to the venous anatomy of the central nervous system and the skull base, as well as by architectural disturbance, specifically, obstruction of the venous outflow.