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  • By Author: Samii, Madjid x
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Guenther Christian Feigl, Otto Bundschuh, Alireza Gharabaghi, Sam Safavi-Abassi, Amr El Shawarby, Madjid Samii and Gerhard A. Horstmann

Object. Chordomas and chondrosarcomas of the skull base are rare locally invasive tumors associated with high recurrence rates. The aim of this study was to evaluate the concept of microsurgical tumor volume reduction followed by early gamma knife surgery (GKS).

Methods. Thirteen patients with 15 tumors were treated between October 2000 and June 2003. There were three patients (23.1%) with chordomas and 10 (76.9%) with chondrosarcomas. There were nine men and four women who ranged in age between 19 and 69 years. All patients first underwent maximal tumor resection. Within 2 to 10 months after surgery they were treated with GKS. The mean postoperative tumor volume treated with GKS was 9.7 cm3 (range 1.4–20.3 cm3). Follow-up computerized tomography and magnetic resonance imaging examinations with volumetric tumor analysis were performed every 6 months after GKS.

The mean treatment dose was 17 Gy and the mean isodose was 52%. The mean follow-up duration was 17 months during which there was only one tumor recurrence at the margin of the radiation field. The mean volume reduction was 35.4%.

Conclusions. Results of this treatment strategy are encouraging but the efficacy of this multimodal treatment combining surgery and early GKS requires a longer follow up.

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Guenther C. Feigl, Otto Bundschuh, Alireza Gharabaghi, Madjid Samii and Gerhard A. Horstmann

Object. The purpose of this study was to evaluate the volume-reducing effects of gamma knife surgery (GKS) of meningiomas with and without previous surgical treatment.

Methods. A group of 127 patients with a mean age of 57.1 years (range 9–81 years) with 142 meningiomas (128 World Health Organization Grade I and 14 Grade II) were included in this study. The management strategy reduces tumor volume with surgery when necessary (81 patients). Stereotactic GKS with a Gamma Knife model C was performed in all tumors of suitable size. Magnetic resonance imaging follow-up examinations with volumetric tumor analysis was performed 6 months after treatment and annually thereafter.

The mean tumor volume was 5.9 cm3 (range < 5 to > 40 cm3). The mean follow-up time after GKS was 29.3 months (range 11–61 months). The mean prescription dose was 13.8 Gy (range 10–18 Gy). A reduction in volume occurred in 117 (82.4%) of all tumors, and in 20 tumors (14.1%) growth ceased. The overall tumor control rate of 96.4%. The mean volume reduction achieved with GKS was more than 46.1%. Only five tumors (3.5%) showed a volume increase.

Conclusions. Gamma knife surgery was effective in reducing meningioma volume at short-term follow up. Further studies are needed to examine the development of these findings over a longer period.