Blood Supply of Cranial Nerves Passing Through the Cavernous Sinus: An Anatomical Study and Its Implications for Microsurgical and Endoscopic Cavernous Sinus Surgery

BackgroundDespite improvements in surgical techniques, cranial nerve (CN) deficits remain the most frequent cause of disability following cavernous sinus (CS) surgery. The most common tumor affecting the CS is meningioma. They originate from lateral wall and have their blood supply from meningohypophyseal trunk (MHT) and inferolateral trunk (ILT). Pituitary adenomas commonly invade the CS through its medial wall and receive blood supply form medial branches of the internal carotid artery (ICA) (superior and inferior hypophyseal arteries). Some tumors may grow within the CS (e.g. trigeminal schwannomas, hemangiomas). These tumors are fed by all the intracavernous ICA branches. Tumors involving the CS may also displace the neurovascular structures, therefore, a better understanding of intracavernous neurovascular anatomy may reduce the postoperative morbidity associated with approaching CS tumors. In this anatomical study, the anatomic variations and their clinical implications of the intracavernous CNs’ blood supply were evaluated through transcranial and endonasal routes.MethodsTwenty sides of ten adult cadaveric formalin-fixed, latex-injected specimens were dissected in stepwise fashion under microscopic and endoscopic magnification. The origin and course of the intracavernous ICA branches supplying the intracavernous CNs are studied.ResultsThe proximal segment of the oculomotor nerve receives blood supply from the ILT in 85%, and the tentorial artery of the MHT in 15% of specimens. The distal segment is exclusively supplied by the ILT. The proximal trochlear nerve receives blood supply from the ILT (75%) and the tentorial artery (25%); the distal segment is exclusively supplied by the superior orbital branch. The proximal third of the abducens nerve receives its vascularity exclusively from the dorsal meningeal artery, and its middle and distal thirds from the ILT. The ophthalmic and proximal maxillary segments of the trigeminal nerve also receive blood supply from the ILT. The distal maxillary segment is supplied by the artery of the foramen rotundum. All ILT branches terminate on the inferomedial aspects of the intra-cavernous CNs. Extensive anastomoses are found between ILT branches and the branches arising from external carotid artery.ConclusionUnderstanding the anatomy of the intracavernous ICA’s branches is important to improving surgical outcomes with tumors involving the CS.

Microsurgical treatment of tentorial dural fistulas causing thalamic venous hypertension: two illustrative sister cases

This video is a presentation of technical tenets for the microsurgical clipping of a tentorial dural arteriovenous fistula presenting with thalamic venous hypertension. These cases are easily misdiagnosed and often supplied by the tentorial artery of Davidoff and Schecter. The cases shown in the video uniquely illustrate a supracerebellar infratentorial approach to identify and clip an arterialized tentorial vein utilizing intraoperative Doppler and fluorescein, with navigation and an intraoperative cerebral angiogram in a hybrid neuroangiography operative suite. Both patients were found to have thalamic edema on preoperative imaging, which significantly improved postoperatively.The video can be found here: https://youtu.be/HmUO6Ye53QI.

Tentorial meningioma supplied by a marginal tentorial artery arising from the superior cerebellar artery: Anatomic and technical considerations

Background and importance The marginal tentorial artery runs over the free edge of the tentorium. Different origins have been described, always involving branches of the carotid artery. We report the superior cerebellar artery as an unknown origin of this artery. We developed our strategy in a case of a tentorial meningioma mainly supplied by this artery. Clinical presentation A 53-year-old man was admitted in our institution for the surgical treatment of a large tentorial and petroclival meningioma. A 2D conventional angiogram was insufficient to detect the tumoral blush. A 3D digital subtraction angiogram (DSA) of the vertebral artery highlighted a blush arising from a marginal tentorial artery fed by the superior cerebellar artery. Selective embolization of this branch led to significant devascularization of the tumor. A total tumor resection was performed 24 h after embolization without complication. The dural medial tentorial artery of the superior cerebellar artery is relatively unknown and courses at the inferior surface of the tentorium. We report the first case in which the marginal tentorial artery arises from this artery. Major bleeding may result from its section or its avulsion from the superior cerebellar artery during surgery; its preoperative diagnosis is thus essential. In this case, a 3D-DSA with dual volume visualization was more sensitive than a 2D conventional angiogram to detect such an anatomic variant. Conclusion The marginal tentorial artery may originate from the superior cerebellar artery. The recognition of this anatomic variant may be essential to avoid hemorrhagic complications during surgery of hypervascular tumors of the tentorium.