Analysis of factors affecting the long-term functional outcome of patients with skull base meningioma.

We analyzed the factors that affect the long-term clinical outcome of a series of patients with skull base meningiomas. Clinical records of 73 patients with cranial base meningiomas were reviewed retrospectively, of whom 13 patients experienced a recurrence at various times following the initial surgery. The mean follow-up time was 90.4 ± 21.2 months (range=60-124 months). Based on the location of the recurrence, patients with recurrence were divided into peripheral (n=6) and central (n=7) skull base groups. Of several variables analyzed using a multivariate logistic regression model, "high MIB-1 (Ki-67 proliferation antigen) labeling index" was an independent variable predicting poor long-term functional outcomes. Recurrence of the tumor at the central skull base was also a strong predictor of poor long-term outcomes. An increased proliferative potential, as indicated by a high MIB-1 labeling index, may induce repeated recurrences, eventually leading to worse functional outcomes, particularly for patients with central skull base meningiomas.