Surgical Anatomy of the Skullbase Venous System : Petroclival Region(Microneurosurgical Anatomy)

The venous structures in the petroclival region, along with the veins leading to the petroclival lesions, are explained along with their anatomical characteristics. 1) The inferior petrosal sinus forms an ampulla called the petrosal confluens at its proximal end. There venous tributaries gather firstly and then drain secondarily to the jugular bulb. The main channel, which is big enough to let an intravenous catheter through, always exists between the IX and X-XI nerves. The main channel often opens below the jugular bulb. The inferior petroclival vein is a small vessel running in the extracranial groove of the petroclival fissure, pouring into the petrosal confluens. Although it is small, when extraordinarily dilated, it might be a useful route to introduce an intravenous catheter. 2) The basilar venous plexus has networks between the IPS of either side. Even when the IPS is obstructed, a catheter can be delivered to the cavernous sinus from the other side via the basilar venous plexus. 3) The petrosal vein can be categorized into three groups according to its draining point: medial, intermediate, and lateral. A petrosal vein of the medial type is most frequent. The most important tributary is the vein of the cerebellopontine fissure, which usually joins the medial petrosal vein. 4) Veins bridging from the temporal lobe to the lateral end of the transverse sinus, including the vein of Labbe, are threatened with avulsion injury during temporal lobe elevation for the transpetrosal approach. The sphenopetrosal sinus should be spared when the middle fossa dura is sectioned to access the petroclival lesions.