Spheno-orbital Meningiomas: A Comprehensive Study on Prognostic Factors and a Novel Classification Approach

Introduction: Spheno-orbital meningiomas (SOMs) arise from the arachnoid villi cap cells at the sphenoid ridge, and have the ability to spread via soft tissue extension and cranial bone invasion. Due to their orbital hyperostosis and intraorbital soft tissue extension, they commonly present with ophthalmologic manifestations. This study aims to investigate the correlation between tumor characteristics and volume with the presenting symptoms and postoperative outcomes. We also propose a novel classification for SOMs.

Methods: This retrospective study analyzed patients who underwent surgical resection of SOMs. Tumor volumes in different compartments were measured using preoperative and postoperative imaging. Linear and logistic regression analyses were used to identify correlations between tumor characteristics and volumes and presenting symptoms preoperatively and postoperative outcomes.

Results: Sixty-six patients were included in this study, of whom 86.4% had proptosis, 80.3% had decreased visual acuity (VA), 30.3% had visual field defects (VFDs), and 13.6% had periorbital edema. Preoperatively, proptosis linearly correlated with intraosseous tumor volume (coefficient = 0.6, p < 0.001), while the decrease in baseline VA correlated with the intraorbital tumor volume (coefficient = 0.4, p = 0.01). The odds of periorbital edema were found to increase with an increase in intraosseous tumor volume with an adjusted odds ratio (aOR) of 1.4 (95% CI, 1.1–1.7, p = 0.003), while the odds of VFDs were found to increase with an increase in intraorbital tumor volume with an aOR of 2.7 (95% CI: 1.3-5.6, p = 0.01). Postoperatively, the volume of intraosseous tumor resected linearly correlated with the improvement in proptosis (coefficient = 0.7, p < 0.001), while the volume of intraorbital tumor resected linearly correlated with improvement in VA (coefficient = 0.4, p < 0.001) and with a larger effect size in patients presenting with moderate to severe decrease in VA preoperatively (coefficient = 0.8). Based on our findings we propose a novel classification system based on the extension of SOMs into different compartments. Our proposed classification system consists of four subtypes: The Intracranial subtype involves the intracranial space with minimal intraosseous component and no intraorbital spread. The intraosseous subtype has an intracranial component along with significant intraosseous tumor invasion. The Intraorbital subtype is characterized by an intracranial component with intraorbital tumor extension yet no intraosseous involvement. Finally, the Intraosseous-Intraorbital subtype comprises tumors with an intracranial component along with significant intraosseous and intraorbital components.

Conclusion: SOMs are complex tumors with often aggressive behavior and multi-compartmental invasion. This study demonstrated that the tumor volumes within specific invaded compartments correlates with presenting symptoms and postoperative outcomes. Accordingly, we introduce a new classification system based on tumor location and invasion extent, enhancing understanding and aiding diagnosis, surgical planning, and prognostic assessment of SOMs.

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Artikel online veröffentlicht:
05. Februar 2024