Circumferential exposure of the cavernous sinus and parasellar region through a combined open and endoscopic endonasal transcavernous approach, a morphometric study

Introduction Although recent trends currently favor the endoscopic endonasal transcavernous approach (EETA) over the pretemporal transcavernous approach (PTA) for certain cavernous sinus pathologies, dedicated assessment of the surgical exposure and maneuverability is wanting. Toward this aim, this morphometric study quantifies these variables within four cavernous sinus compartments by comparing the PTA, EETA, and a combined approach to achieve a circumferential dissection (EETA-PTA). Material In five latex-injected specimens, exposure volumes of the EETA, PTA, and circumferential EETA-PTA approaches were quantified; the latter combined the most conservative options of both the endoscopic and open approaches. Two clinical cases illustrate the combined approach. Results EETA-PTA provided the largest volume of exposure (65.6% vs 35% PTA vs 44.6% EETA, P = 0.01) and eliminated the need to mobilize the ICA or cross cranial nerves. Although EETA and PTA approaches afforded comparable exposure volumes along the entire cavernous sinus (34.9 vs 44.6%), the EETA better exposed medial and inferior compartments (whereas the PTA exposed larger volumes in the lateral and superior compartments. The combined EETA-PTA yielded 66% of total cavernous sinus exposure volumes and eliminated the need to mobilize the ICA or cross cranial nerves. Conclusions Our methodology aligns with strategies that use a modular concept to divide the skull base into compartments for maximal safe resection. Excluding soft tumors, the EETA is preferred for medial and inferior lesions and the PTA for superior and lateral lesions. A staged combined EETA-PTA may safely yield a 360-degree access for extensive multi-compartment lesions that span neurovascular structures within the cavernous sinus.