Endoscopic Transsphenoidal versus Microscopic Transcranial Approach for Anterior Skull Base Meningiomas: A Meta-analysis

Introduction: The mainstay of treatment of anterior skull base meningiomas, including Tuberculum Sellae Meningiomas (TSM) and Olfactory Groove Meningiomas (OGM), is surgery. This can be challenging given the surrounding vital structures. Traditionally, these meningiomas are resected using a microscopic transcranial approach (TC). In the past decade, however, the endoscopic endonasal transsphenoidal approach (eTSS) has offered an alternative corridor for both TSM and OGM. However, it remains to be elucidated which approach offers the best surgical outcomes. The TC and eTSS approaches are compared and contrasted.

Methods: A systematic Embase and PubMed search was conducted to identify relevant articles on surgical outcomes of TSM and OGM from January 2005 until December 2015. Articles were excluded based on predetermined exclusion criteria, which included: articles not in English, case reports, reviews, cadaveric studies, studies with endoscopic assistance in the endonasal group, giant (>6cm) OGMs and congress abstracts. Comprehensive Meta-analysis (CMA) software was used to calculate fixed overall prevalence with 95%-confidence interval (CI) for TSM and OGM for gross total resection (GTR), visual improvement, post-operative cerebral spine fluid (CSF) leakage, mortality and internal carotid artery (ICA) injury in eTSS and TC respectively.

Results: The search resulted in 773 case series that were screened for title and abstract, resulting in 172 articles that were screened full text. Of these, 43 articles were included in the meta-analysis. For TSM resections, pooled fixed prevalence and subgroup analysis by surgical approach revealed that eTSS was associated with a higher mortality (6.50%; 95%-CI: 3.00–13.9%; I2=0%) than TC (2.40%; 95%-CI: 1.5–4.0%, I2=0%) (P-interaction comparing the two groups = 0.04). However, eTSS was not significantly different from TC with respect to GTR (P-interaction = 0.09), visual outcome (P-interaction = 0.24), CSF leak (P-interaction = 0.09) or increased rate of ICA injury (P-interaction = 0.12). For OGM resections, eTSS as compared with TC was associated with decreased GTR (68.2%; 95%CI: 56.4–78.1%; I2=0% for eTSS versus 88.8%; 95%-CI: 85.7–91.3%, I2= 50.7% for TC) (P-interaction comparing the two groups: <0.01), poorer visual outcome (28.5%; 95%CI: 18.4–41.4%; I2=54.3% for eTSS versus 74.2%; 95%-CI: 64.3–82.2%; I2=58.4% for TC)(P-interaction comparing the two groups = 0.02) and greater CSF leak incidence (29.7%; 95%-CI: 20.6–40.8%; I2=0% for eTSS versus 10.7%; 95%-CI: 8.2–13.8%; I2=66.0% for TC)(P-interaction comparing the two groups = 0.005). However, eTSS was not associated with ICA injury (P-interaction = 0.14) or increased mortality (P-interaction = 0.99) when compared with TC. Further subgroup analyses by age, gender and continent where the study was performed showed no significant differences between these groups (all P-interaction>0.05).

Conclusion: The eTSS approach for TSM was associated with higher mortality when compared with TC, but not morbidity. For OGM, TC resulted in greater GTR rate, visual improvement and fewer CSF leaks. Based on this study, we conclude that even though the eTSS approach could be an alternative for selective patients, the microscopic transcranial approach is still a useful and valid technique for the resection of anterior skull base meningiomas. However, as technology and expertise expand, eTSS outcomes could continue to improve for these meningiomas.