The classical supraorbital minicraniotomy to approach the areas of origin of anterior skull base meningiomas: Anatomical nuances influencing accessibility, operability, and frontal lobe retraction.

Abstract

The classical supraorbital minicraniotomy (cSOM) constitutes a minimally invasive alternative for the resection of anterior skull base meningiomas (ASBM). Surgical success depends strongly on optimal patient selection and surgery planning, for which a careful assessment of tumor characteristics, approach trajectory, and bony anterior skull base anatomy is required. Still, morphometrical studies searching for relevant anatomical factors with surgical relevance when intending a cSOM for ASBM resection are lacking. Bilateral cSOM was done in five formaldehyde-fixed heads toward the areas of origin of ASBM. Morphometrical data with potential relevant surgical implications were analyzed. The more tangential position of the cSOM with respect to the olfactory groove (OG) led to a reduction in surgical freedom (SF) in this area compared to others (P < 0.0001). Frontal lobe retraction (FLR) was also higher when approaching the OG (P < 0.05). Olfactory nerve mobilization was higher when accessing the planum sphenoidale (PS), tuberculum sellae (TS), and anterior clinoid process (ACP) (P < 0.0001). OG depth and the slope of the sphenoid bone between the PS and TS predicted lower SF and higher frontal retraction requirements along the OG and TS, respectively (P < 0.05). In contrast, longer distances to the ACP tip predicted lower SF over this structure (P < 0.01). Although clinical validation is still needed, the present anatomical data suggest that assessing minicraniotomy's position/extension, OG depth, the sphenoid's slope, and distance to ACP-tip might be of particular relevance to predict FLR, maneuverability, and accessibility when considering the cSOM for ASBM resection, thus helping surgeons optimize patient selection and surgical strategy.