Radiographic Evaluation and Clinical Implications of Venous Connections Between Dural Arteriovenous Fistula of the Cavernous Sinus and Cerebellum and the Pontomedullary Venous System

The types of cortical venous reflux channels, posterior fossa and pontomesencephalic venous reflux or their connections with the cavernous sinus (CS) are inadequately described in the literature. This study uses angiography, magnetic resonance imaging, and X-ray computed tomography to clarify the possible route of cavernous dural arteriovenous fistulae (CVDAVF) that causes posterior fossa and pontomedullary venous reflux and documents the clinical presentations associated with the reflux. Eighty-six patients with CSDAVF treated at Ramathibodi Hospital, Bangkok, Thailand, during 2009 to 2013 were studied retrospectively. Sixteen cases with posterior fossa and pontomedullary venous reflux were included for analysis. Bridging veins serve as an important pathway for venous reflux from CS to the posterior fossa and brainstem. The uncal vein directly terminates at the CS and has several connecting routes, ranging from the inferior frontal lobes and insula to the posterior fossa through the basal vein of Rosenthal. The petrosal vein was most frequently and easily detected angiographically. It plays a major role in the cerebellar hemispheric venous reflux. Only 1 patient developed brainstem and cerebellar venous congestion, which returned to normal after endovascular treatment. Connections of CS are not limited to intercavernous, ophthalmic veins, sphenoparietal sinuses, and inferior and superior petrosal sinuses. They also occur with complex venous drainages at the base of the frontotemporal lobes, insula, brainstem, and cerebellum. Knowledge of the venous connection of CS is key to understanding the possible locations of venous congestion/hemorrhage and the clinical presentation of patients with CSDAVF.