1235. Tentorial Venous Anatomy: Cadaveric and Radiographic Study

Authors: Jared Rosenblum; Mateus Neto, MD; Walid Essayed, MD; Wenya Bi, MD, PhD; Nirav Patel; Mohammed Aziz-Sultan, MD; John Heiss, MD; Ossama Al-Mefty, MD (Bethesda, MD)

Introduction: The skull base surgeon may need to manipulate or section the tentorium to widen the surgical corridor. Few studies have examined tentorial venous anatomy and how surgical maneuvers might affect it. Described medial and lateral tentorial sinus configurations inadequately explain intraoperative tentorial vascularity and postoperative complications of tentorial manipulation. To better understand disparate outcomes in two clinical cases 1) remote cerebellar infarct following temporal lobe glioma resection and 2) tolerance of bilateral transverse sinus thrombosis, we studied tentorial veins in 2 cadavers and reviewed embryologic development of tentorial vessels. Methods: The tentorium was isolated in two un-injected fresh cadaver head specimens, preserving bridging veins. Tentorial venous anatomy was observed by transillumination before and after methylene blue injection of dural and tentorial sinuses. We applied our cadaver, MRI, and CT-Venogram findings to explain outcomes of 2 intracranial surgical cases. Results: In cadavers, veins from both the transverse and straight sinuses entered a distended plexus of tentorial veins that in turn communicated with supra- and infratentorial bridging veins. This elaborate network of tentorial venous channels was also seen by MRI in our 2 patients. The first patient developed venous infarction after tentorial manipulation compromised adjacent brain venous drainage. Conversely, our second patient remained well after bilateral transverse sinus occlusion because the accessory venous system within the tentorium bypassed the occlusions. Conclusions: We identified a consistent trans-tentorial venous system. These veins, previously reported to obliterate in completed development of the tentorium, indeed remained patent with a consistent configuration. In case 1, loss of tentorial drainage resulted in remote thrombosis of an infratentorial bridging vein and cerebellar venous infarction. In case 2, bilateral transverse sinus thrombosis was asymptomatic because accessary tentorial venous channels bypassed the occlusions.