Endoscopic endonasal resection of skull base meningiomas: the significance of a "cortical cuff" and brain edema compared with careful case selection and surgical experience in predicting morbidity and extent of resection.

This paper describes a consecutive series of skull base meningiomas resected using an endoscopic endonasal approach through various corridors at a single institution over 7 years. The impact of case selection and experience, the presence of a cortical cuff between the tumor and surrounding vessels, and brain edema on morbidity and rates of gross-total resection (GTR) were examined. A retrospective review of a series of 46 skull base meningiomas from a prospective database was conducted. The series of cases were divided by location: olfactory groove (n = 15), tuberculum and planum (n = 20), sellar/cavernous (n = 9) and petroclival (n = 2). Gross-total resection was never intended in the sellar/cavernous tumors, which generally invaded the cavernous sinus. Clinical charts, volumetric imaging, and pathology were reviewed to assess the extent of resection and complications. Cases were divided based on a time point in which surgical technique and case selection improved into Group 1 (surgery prior to June 2008; n = 21) and Group 2 (surgery after June 2008; n = 25) and into those with and without a cortical cuff and with and without brain edema. Improved case selection had the greatest impact on extent of resection. For the entire cohort, rates of GTR went from 38% to 76% (p = 0.02), and for cases in which GTR was the intent, the rates went from 63% to 84% (not significant), which was mostly driven by the planum and tuberculum meningiomas, which went from 75% to 91.7 % (nonsignificant difference). The presence of a cortical cuff and brain edema had no impact on outcomes. There were 3 CSF leaks (6.5%) but all were in Group 1. Hence, CSF leak improved from 14.2% to 0% with surgical experience. Lessons learned for optimal case selection are discussed. Surgical outcome for endonasal endoscopic resection of skull base meningiomas depends mostly on careful case selection and surgical experience. Imaging criteria such as the presence of a cortical cuff or brain edema are less important.