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

Abstract

Objectives: Anterior transpetrosal approach involves extradural exposure of the postero-medial (Kawase) triangle which is bounded by the Arcuate eminence, the Greater Superficial Petrosal Nerve (GSPN) and the Petrous ridge. Despite permitting a key access, the exposure is conical and crowded; it does not allow proper exposure to the Vth nv. exiting from the tentorium, the VI th nerve in the Dorello canal and the the posterior clinoid process. Methods: Retrospective analysis of a spectrum of patients operated by the modified anterior transpetrosal rhomboid approach was performed. Results: 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 Gasserian Ganglion (anterior). Ligation and division of the superior petrosal sinus close to the posterior clinoid process and gentle elevation of the V nerve root permits enlarged view of the previous inaccessible areas. Posterior cavernous anterior transpetrosal posteromedial rhomboid (Dolenc-Kawase rhomboid) approach was used in the treatment of petroclival meningiomas (32), Trigeminal schwannoma (11), clival chordoma (6), clival chondrosarcoma (4), IV schwanomma (1), giant posterior fossa craniophrangioma (4), middle + posterior fossa epidermoid (2), ?hypothalamic hamartoma (1), giant low basilar bifurcation aneurysm (2), petroclival hemangiopericytoma (1) and petroclival, cavernous and tentorial histiocytosis (Rosai Dorfman). Conclusions: Posteromedial rhomboid petrous apex approach is technically demanding and requires a thorough knowledge of skull base anatomy and pathology; it provides safe corridor during the microsurgical treatment of a spectrum of skull base lesions.