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Periclinoid and Pericavernous Surgical Corridors to the Cavernous Sinus: An Extensive Anatomosurgical Analysis
05 February 2020 (online)
Background: Lesions involving the cavernous sinus (CS) represent some of the most challenging pathologies of the skull base due to the dense surrounding neurovasculature. Extradural exposure and preparation of this region, whether as initial preparation for a combined intra-extradural approach or as the main avenue of surgical exposure, can enlarge surgical corridors and minimize retraction. We describe the surgical approaches to this region, the entry corridors to the CS that are available within each approach, and the surgical exposure provided by each of these corridors. Additionally, we describe and demonstrate how extradural and intradural preparation of these surgical corridors can be used to widen the available working space and facilitate surgery of the CS.
Methods: Pterional, frontotemporal-orbital, frontoorbitozygomatic, frontozygomatic, conservative perilabyrinthine transtentorial, and endoscopic transnasal transsphenoidal approaches were performed on cadaveric heads to access the periclinoid and pericavernous regions. Periclinoid techniques (cutting of the meningoorbital band, anterior clinoidectomy, unroofing of the superior orbital fissure, unroofing of the optic canal, displacement of the extra-annular structures, opening of the annulus of Zinn, and extradural dissection of the CS), pericavernous techniques (cutting of the distal dural ring, falciform ligament, and optic sheath; mobilization of the supraclinoid ICA, opening of the porus oculomotoris, and mobilization of CN III), and peritrigeminal techniques (mobilization of CN's V2 and V3), along with other maneuvers were performed. The CS was divided into eight anatomical compartments and nine entry corridors were described, and exposure was assessed accordingly.
Results: The standard pterional transsylvian approach provided access solely to the intradural parasellar entry corridor into the superior wall of the CS. Extending this approach with an extradural anterior clinoidectomy and unroofing of the optic canal allowed for application of the pericavernous maneuvers and enlargement of the entire parasellar corridor and exposure of the carotid cave. The extradural pterional approach, with or without removal of the anterior clinoid, was allowed for limited access, only one of the six corridors, into the lateral wall of the CS. The frontotemporal-orbital approach also provided access extradurally to one entry corridor and intradurally to the posterior portion of the parasellar corridor. Extending this approach with the periclinoid and pericavernous maneuvers allowed for full exposure of three of the lateral wall corridors and an enlarged parasellar corridor. The frontoorbitozygomatic approach provided access extradurally to four of the corridors into the wall, as well as the posterior portion of the intradural parasellar corridor. Application of periclinoid, pericavernous, and peritrigeminal maneuvers, allowed for exposure of all six lateral wall entry corridors, as well as an enlarged parasellar corridor. The frontozygomatic approach provided access to three lateral wall corridors extradurally, and the posterior parasellar window intradurally, all of which were expanded following pericavernous and peritrigeminal maneuvers. The conservative perilabyrinthine transpetrosal transtentorial approach to the posterior wall was enlarged with opening of Dorello's canal and the endoscopic transnasal transphenoidal approach was enlarged with opening of the optic canal.
Conclusion: Extradural exposure is essential whether as initial preparation for a combined intraextradural approach or as the main avenue of CS surgical exposure.