Gamma-Knife Radiosurgery for Skull Base Meningiomas: Experience of Tumor Control, Clinical Course and Morbidity in a Follow-Up of More Than 8 Years

Abstract

Objective: Surgical resection of skull base meningiomas is often limited due to involvement of crucial neural structures. Within the last two decades gamma-knife radiosurgery (GKRS) gained increasing importance as adjunct treatment following incomplete resection and as an alternative treatment to open surgery. However, reports of long-term results are still sparse. We therefore performed this study to analyze the long-term results of GKRS treatment of skull base meningiomas, following our previously published early follow-up experience. Methods: A retrospective analysis was conducted of the medical files for gamma-knife and surgical treatments; clinicoradiological findings and outcomes were assessed, focusing on tumor control, clinical course, and morbidity. Results: Between 1992 and 1995, we treated 36 patients with skull base meningiomas using GKRS (male-to-female ratio, 1:5; mean age, 59 years; range, 44–89 years). Twenty-five patients were treated with GKRS following open surgery, and 11 patients received GKRS alone. Tumor control, neurological outcomes, and adverse effects were analyzed after a long-term follow-up period (mean, 103 months; range, 70–133 months) and compared with our previous results after an earlier, shorter follow-up period (mean, 48 months; range, 36–76 months). Control of tumor growth was achieved in 94% of patients. Compared with the early follow-up period, the late neuroradiological effects of GKRS on skull base meningiomas were: continuing tumor shrinkage in 11 cases (33%), stable tumor size in 20 cases (64%), and tumor progression in 2 meningiomas (6%). The neurological status revealed improvement in 16 patients (44%), stabilization in 19 patients (52%), and deterioration in 1 patient (4%). Adverse side effects of GKRS were found during the early follow-up period only. Conclusions: Our data confirm that GKRS is not only a safe and effective treatment modality for skull base meningiomas in a short-term observation period; its safety and effectiveness was also concluded in a mean long-term follow-up period of more than 8 years, and tumor shrinkage and clinical improvement was found to continue during the long-term follow-up period.