gms | German Medical Science

Objective: Radical surgical resection of skull base tumors is limited in many cases because of the danger of involving crucial neural structures. Within the last 2 decades the efficacy of Gamma Knife radiosurgery (GKRS) has been proven for treatment of intracranial tumors. Thus it gained increasing importance as an adjunct treatment after incomplete tumor resection or even as an alternative to surgery. However, data on a combined therapy concept consisting of microsurgical resection followed by GKRS are still sparse in the literature. Therefore the aim of the investigation was to analyze the long-term results of patients suffering from benign skull base tumors treated by this combined approach in our department.

Methods: A retrospective analysis of all patients treated by both subtotal microsurgical tumor resection and GKRS between 2001 and 2006 was performed. Clinical outcome was evaluated in respect to new cranial nerve deficiency and the Karnovsky scale. Control of tumor growth was performed by analyzing the follow-up MRI scans.

Results: During the observation period, 53 patients with cranial base tumors were treated by a combination of microsurgery and GKRS. A follow-up of 36 months (mean 36,6; 14,1±SEM, range, 6-58) could be achieved. The histology of the tumors included meningeoma (30/5 °II), Schwannomas (9), pituitary adenoma (8/3 secretory), chordoma (1), glomus-Tumor (1), craniopharyngeoma (1), hemangiopericytoma °II (1). A new functionally relevant and permanent cranial nerve deficit occurred in 3 cases after microsurgery (5,7%) and was not observed after GKRS. The median Karnovsky scale was 100 (pre-operative), 90 (post-operative) and 90 after GKRS. The neurological status remained stable in all patients after GKRS. Minor adverse side effects of GKRS were found only during the early follow-up period (<1 year). Control of tumor growth on the MRI was achieved in 89% of patients. In 20 patients (38%) shrinking of the tumor occurred. A stable tumor size was observed in 27 patients (51%) and tumor progression in 6 (11%). Further resection or radiosurgical treatment had to be performed in 4 cases (2 meningiomas °II, 1 chordoma, 1 non-functioning pituitary adenoma). All other cases are clinically well-controlled. KPS is better then 80 in all patients.

Conclusions: Our data confirm that a combined treatment strategy using microsurgery and GKRS produces a good tumor control rate with a good functional outcome and an acceptable peri-procedural morbidity. Therefore, it represents a successful concept in selected patients suffering from skull base tumors.