Minimal Access Endonasal versus Supraorbital versus Transorbital Surgery for Skull Base Meningiomas in the Anterior and Middle Fossa: A Comparative Analysis

Introduction: Minimally invasive approaches to the anterior skull base offer an alternative to traditional open craniotomies for meningiomas. Case selection is critical to success. Here, we compare the supraorbital approach (SOA), endoscopic endonasal approach (EEA), and transorbital approach (TOA) to skull base meningiomas in different locations and their impact on patient outcomes.

Methods: A consecutive patient series who underwent SOA, EEA, or TOA for newly diagnosed meningiomas of the anterior-middle fossa skull base between 2007-2022 were included. Probabilistic heat-maps were created to display the actual distribution of tumor volumes based on surgical approach. Tumor volume, GTR, EOR, sensory outcomes, and postoperative complications were assessed.

Results: 88 patients were included in this study. EEA in 44 patients, predominantly for planum and tuberculum meningiomas; SOA in 36 patients, predominantly for olfactory groove and anterior clinoid meningiomas; and TOA in 8 patients for spheno-orbital and middle fossa meningiomas. The largest tumors were treated with SOA (28±29 cm3), followed by TOA (10±10 cm3), and EEA (9±8 cm3)(p=0.024). Most cases (91%) were WHO grade I. GTR was achieved in 74(84%) patients: 33(92%) SOA, 37(84%) EEA, 4(50%)TOA(p=0.014). The mean extent of resection was 97±10% across all tumors and differed across approaches (98.6±5% SOA, 98.4±6% EEA, and 79.8±23% TOA;p=0.005). There were 15 recurrences: 7 SOA, 7 EEA, and 1 TOA(p=0.859).

Conclusion : Minimally invasive approaches for removal of anterior skull base meningiomas require careful case section based on the anatomic location and extent of the tumors. SOA and EEA resections achieve high rates of GTR and improvements in vision with limited complications. The TOA had comparably less GTR, but this arose from the spheno-orbital meningiomas where alleviation of proptosis and not GTR was the goal of surgery. Interestingly, EEA led to higher rates of new anosmia than SOA, despite that more olfactory groove meningiomas were removed through SOA.