Lateral sphenoid wing meningiomas without bone invasion-still skull base surgery?

Sphenoid wing meningiomas are generally considered as skull base meningiomas (SBMs). However, given their surgical similarities with non-skull base meningiomas (NSBMs), we hypothesized that lateral sphenoid wing meningiomas (LSWMs) without bone invasion (BI) should be considered as NSBMs. N = 65 LSWMs without BI operated between 1990 to 2010 at a single-center were compared to N = 352 NSBMs, represented by convexity meningiomas (CMs), and to N = 23 SBMs, represented by spheno-orbital meningiomas (SOMs), with respect to baseline demographics, clinical presentations, Simpson grades, complications, adjuvant therapies, as well as overall survival (OS) and progression-free survival (PFS). Only WHO grade I meningiomas were included. No significant differences in baseline demographics, clinical presentation, or pre-operative KPS were found between the three groups. Simpson grade 1-3 was achieved in 90.1% of LSWMs, 97.1% in CMs (p = 0.05), and 82.6% in SOMs (p = 0.23). There were no significant differences in postoperative infection, hematoma, neurological worsening, 30-day mortality, or OS between the three groups. Lower re-treatment rates were observed in LSWMs and CMs compared to SOMs (p = 0.06). With respect to PFS, there was no significant difference between LSWMs and CMs (89.1% and 88.5% at 5 years, respectively), whereas PFS was significantly higher in LSWMs than in SOMs (79% at 5 years) (p = 0.05). LSWMs without BI should be considered as an intermediate entity between NSBMs and SBMs. LSWMs are similar to SOMs with respect to extent of resection, but more similar to CMs with respect to re-treatment rates and PFS.