Endoscopic Endonasal and Supraorbital Keyhole Surgery for the Management of Anterior Skull Base Meningiomas: Overcoming the Barriers between Above and Below Approaches

Background The resection of anterior skull base meningiomas has traditionally been performed via pterional or unilateral/bilateral subfrontal craniotomies. The supraorbital keyhole approach (SKA) and the endoscopic endonasal approach (EEA) were developed to provide alternative and less-invasive approaches, actually not so much to increase the already high rate of resection but to reduce the manipulation on healthy tissue surrounding the lesions to reduce the complications rate. Supporters of the EEA emphasize the lack of retraction and less manipulation of the brain, early tumor devascularization, and maximal resection of the base of the skull that may be infiltrated by the meningioma. Conversely, defenders of SKA highlight the advantages of the faster surgical route, better vascular control, potential to preserve olfactory function, and lower rates of postoperative CSF leakage. At the beginning of our experience, the two approaches were used alternately based on the characteristics of meningiomas, while in the last few years more often they have been used in combination. In fact, the combined EEA-SKA offers two complementary surgical corridors that may potentially maximize meningioma resection and minimize complications.

Methods A total of 44 cases were selected and divided according to operative technique into three different groups: purely EEA (18 cases); purely SKA (microscopic with eventual endoscopic assistance; 19 cases); and combined EEA with SKA (7 cases). The three surgical techniques were analyzed and compared concerning working angles, exposure of the lesion and vascular control, complications, surgical radicality, endocrinologic and ophthalmologic outcome, and recurrence rate at patients' follow-up.

Results Gross-total resection was achieved in 72.22% of the endonasal cases (13 patients out of 18), 76.47% of the SKA cases with endoscopic assistance (17 patients out of 19), and 83.3% of the combined cases (6 patients out of 7). In EEA group, three patients presented CSF leak that required surgical revision and 11 patients developed complete anosmia. In the SKA group, two cases of postoperative frontal lobe contusion/hemorrhage were registered which only one required surgical intervention. One CSF leak treated conservatively. In the combined group, no major surgical complications occurred.

Conclusion In well-selected cases, both approaches provide a minimally invasive surgical route with adequate working angles to control the meningioma. We confirm the gold general rule that the ideal approach should be tailored on individual basis considering the tumor anatomy, lateral extension, vascular encasement, and infiltration of the skull base. Larger tumors, in our opinion, are better approached by classical approaches, and even using the combined EEA-SKA approach can, in selected cases, provide the same result with potentially less complication rate.