Posterior Cavernous Anterior Transpetrosal Posteromedial Rhomboid (Dolenc-Kawase Rhomboid) Approach to Posterior Cavernous and Petroclival Lesions

The anterior transpetrosal approach involves extradural exposure of the posteromedial (Kawase) triangle, which is bounded by the arcuate eminence, the greater superficial petrosal nerve (GSPN), and the petrous ridge. It allows exposure of the tentorium and the middle fossa and the posterior fossa up to the internal auditory meatus. Despite permitting a key access point, the exposure is conical and crowded; it does not allow proper exposure to the Vth nerve. Exiting is from the tentorium, the VIth nerve in the Dorello canal, and the undersurface of the attachment of the tentorium to the posterior clinoid process. Dissection of the posterior cavernous sinus wall over the V2, V3, and gasserian ganglion permits access to a posteromedial rhomboid bounded by the arcuate eminence (posterior), GSPN (lateral), the petrous ridge (medial) and V3, and the gasserian ganglion (anterior). Ligation and division of the superior petrosal sinus close to the posterior clinoid process and gentle elevation of the Vth nerve root permit an enlarged view of the previous inaccessible areas. A posterior cavernous anterior transpetrosal posteromedial rhomboid (Dolenc-Kawase rhomboid) approach with or without zygomatic osteotomy was used in the treatment of petroclival meningiomas (32); giant dumbell trigeminal schwannoma (11); clival chordoma (6); clival chondrosarcoma (4); trochlear schwannoma (1); giant posterior fossa craniopharyngioma (4); middle + posterior fossa epidermoid (2); hypothalamic hamartoma (1); giant low basilar bifurcation aneurysm (2); petroclival hemangiopericytoma (1); and bilateral petroclival, cavernous, and tentorial histiocytosis (Rosai-Dorfman).

The conclusion of this study is that a posteromedial rhomboid petrous apex approach is technically demanding and requires a thorough knowledge of skull base anatomy and pathology; it provides a safe corridor during the microsurgical treatment of a spectrum of skull base lesions.