Combination of Surgery and Gamma-Knife Radiosurgery for the Treatment of Complex Skull Base Meningeomas

Introduction: The efficacy of a treatment concept combining total/subtotal tumor removal of skull base meningiomas with Gamma-knife radiosurgery(GKS) for residual/recurrent tumors aiming at highest functional preservation is assessed.

Material and Methods: Twenty-three patients (ages: 49.8 ± 11.6 years; 18 female, 5 male) with complex meningiomas of the cavernous sinus (n = 11), the cerebellar pontine angle (n = 3), the sphenoid wing (n = 3), and the petroclival area (n = 6) were treated by surgery and Gamma-knife surgery. GKS was performed in case of recurrency or after subtotal resection either shortly after surgery or after regrowth of the tumor. Complete neurological follow-up information was available for all patients. Follow-up examinations included stereotactic magnetic resonance imaging for sequential measurements of the tumor volume.

Results: All patients underwent surgery prior to radiosurgery. Subtotal removal was performed in 17 cases, total removal in 6 cases. Gamma-knife surgery was applied at a median of 32 weeks after surgery. The median dose to the tumor margin was 16.7 ± 5.7 Gy (range: 11–34 Gy). The mean prescription isodose was 50% (range: 45–75%). Median follow-up after GKS was 48 months. Using both methods tumor control was achieved in 91% (n = 21) of the cases. Focusing on visual disturbances, our preliminary data show that 13 patients had a visual deficit prior to surgery. After surgery 5 patients improved, 4 patients remained stable, 5 patients had some additional impairment. Radiosurgery did not cause additional visual disturbances. Since introduction in 2001 of a modified surgical strategy aiming at functional preservation instead of radicality by any circumstances no severe additional visual disturbance occurred due to therapy.

Conclusions: Limited surgery combined with postoperative GKS for residual or recurrent meningiomas is an effective and safe treatment option for complex tumors of the skull base. In terms of a conflict between radicality of surgery and functional preservation, tumor control with preserved function turned out to be a feasible concept with far better results.