Tucci M, Chaiyamoon A, Suwannakhan A, Cardona JJ, Comert A, Iwanaga J, Dumont AS, Tubbs RS
Abstract
BACKGROUND: The internal jugular vein (IJV) is the pre-eminent outflow of the dural venous sinuses (DVS) in the supine position, while the vertebral venous plexus (VVP) dominates venous outflow in the upright position. Emissary veins can also be an accessory pathway for this venous egress. To our knowledge, alternative dural venous sinus directly drainage via the diploic space has not been previously reported in the literature. METHODS: Ten fresh frozen adult cadavers underwent exposure of the basilar venous plexus. The entire plexus, still adhered to the underlying clivus, was removed with its u nderlying bone and submitted for histological examina-tion following decalcification (Masson Trichrome, 5mm slices). RESULTS: All specimens were found to have direct communication between the basilar venous plexus and u nderlying diploic space of the clivus i.e., no intermediate clival emissary vein. These were concentrated near the midline and were more numerous over the clivus near the junction of the occipital and sphenoid bones. The endo-thelium of the venous sinus was continuous at the opening into the diploic space and these openings ranged in size from 500 to 750 mm (mean 650 mm). CONCLUSIONS: An improved understanding of the ce-rebral venous drainage can assist clinicians and surgeons in recognizing normal, pathologic, and variant anatomy in this region. Based on our study, direct venous sinus (DVS) to diploic space drainage offers an additional pathway for venous egress from the intracranium. Therefore, removal of the dura over the clivus during various skull base pro-cedures might be associated with increased venous bleeding from the basilar venous plexus on its deep sur-face where it interfaces with the clivus.
