Microscopic and Endoscopic Extracranial Approaches to the Cavernous Sinus: An Anatomical Study and Clinical Implications

Background and Objective: In the last two decades, various extracranial approaches to the cavernous sinus (CS), either with the microscopic or endoscopic technique, have been described. The aim of this study is to describe the distinctive anatomical features of these approaches and compare their efficacy in exposing the sellar and parasellar areas. The clinical experiences of the senior authors with the microscopic sublabial and the endoscopic endonasal transsphenoidal approaches are also reviewed.

Materials and Methods: Ten adult cadaver heads with red latex injected in the arterial system were used. Five different approaches were performed: (1) endonasal microscopic transsphenoidal approach; (2) sublabial microscopic transsphenoidal approach, including its variation described by Fraioli; (3) transmaxillary microscopic approach; (4) paraseptal endoscopic transsphenoidal approach; and (5) trans-ethmoid-pterygoid-sphenoidal endoscopic approach (EPSea). The CS exposition was evaluated for each approach, and a grading system, which considers surgical maneuverability as well as visualization, was used. Surgical exposure, trajectories, and maneuverability were also assessed with a neuronavigation system.

Results: The medial CS compartment is well exposed with endoscopic and microscopic transsphenoidal approaches, but it is insufficiently exposed with the transmaxillary approach. The variation of the sublabial microscopic approach suggested by Fraioli allows its widest microsurgical exposure. The lateral compartment is well visualized using the transmaxillary microscopic and the endoscopic approaches. The major anatomical structures that may limit exposure to the lateral compartment of the CS are the posterior ethmoid and medial pterygoid processes.

Conclusions: The sublabial transsphenoidal microscopic approach, with its variations, allows the most versatile extracranial microscopic exposure of the sella and CS. The paraseptal, binostril endoscopic approach allows a very good exposure of the CS; EPSea achieves the best maneuverability in the lateral compartment of the CS. In the clinical setting, the paraseptal endoscopic endonasal transsphenoidal approach with a middle turbinectomy allows satisfactory visualization and maneuverability within the parasellar compartment.