Radiosurgery for intracranial meningiomas.

Lee JY,  Prog Neurol Surg. 2007;20:142-9.

Department of Neurological Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pa., USA.

Introduction: Meningiomas are common intracranial benign tumors that can be surgically excised. However, their intimate involvement with critical neurovascular structures often prevent their complete resection. Gamma Knife radiosurgery is a minimally invasive option which provides excellent tumor control as both an adjunct and primary therapy. Materials and Methods: Between September 1987 and December 2004, 964 patients underwent Gamma Knife radiosurgery at the University of Pittsburgh for the diagnosis of meningioma. The majority of patients had tumors located at the skull base. All imaging and clinical follow-up was reviewed. Results: Overall, Gamma Knife radiosurgery provides 5- and 10-year actuarial tumor control rates of 93% for benign meningiomas. The 5-year actuarial control rate for patients with atypical and malignant meningiomas was 83 +/- 7 and 72 +/- 10%, respectively. The incidence of adverse radiation effect ranged from 5.7 to 16%; however, the incidence was gradually reduced with the advent of magnetic resonance imaging and lower dosing since 1991. Conclusion: Gamma Knife radiosurgery is an attractive option for patients with intracranial meningiomas. It can be used as both primary treatment based on imaging diagnosis alone, or as an adjunct treatment after craniotomy. It provides long-term tumor control with minimal adverse sequelae.

Complications after gamma knife radiosurgery for benign meningiomas

Department of Neurosurgery, Brain Research Institute, and BK 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea

Objectives: To analyse the results of gamma knife radiosurgery (GKS) for the trreatment of intracranial meningiomas and to assess possible factors related to the outcome and complications of such treatment.

Methods: The authors retrospectively reviewed the clinical and radiological data of 179 patients (194 lesions) treated with GKS for meningiomas between May 1992 and October 2000. The mean follow up duration was 37.3 months (range 6.4 to 86.3 months). The study determined the correlation between radiosurgical outcome including imaging changes after GKS and multiple factors such as tumour location and size, patient characteristics, venous sinus status, pre-GKS degree of oedema, other treatment modalities, and radiosurgical parameters.

Results: The radiological control rate was 97.1%. Magnetic resonance imaging (MRI) showed complications after GKS in 35 lesions (25.0%) among the 140 lesions followed up with MRI. Complications were divided into peritumorous imaging changes (33 lesions; 23.6%) and transient cranial nerve dysfunction (two lesions; 1.4%). Radiation induced imaging changes were seen mostly in convexity, parasagittal, and falx meningiomas that were deeply embedded in the cortex. About 60% of these were asymptomatic and the overall rate of symptomatic imaging changes was 9.3%. Neurological deficit related to imaging changes developed in only three patients, and all the symptoms were transient.

Conclusion: GKS for intracranial meningiomas seems to be a safe and effective treatment. However, meningiomas of the convexity, parasagittal region, or falx cerebri have a higher incidence of peritumorous imaging changes after GKS than those of the skull base. Therefore, the use of GKS needs to be considered very cautiously in cerebral hemispheric meningiomas, taking into consideration patient age and general condition, tumour size and location, pattern of cortical embedding, relation between the tumour and venous sinuses, presenting symptoms, and patient preference.

Stereotactic radiosurgery for atypical and anaplastic meningiomas.

Kano H,  J Neurooncol. 2007 Mar 15;

Department of Neurosurgery, Kishiwada City Hospital, Osaka, Japan.

Atypical and anaplastic meningiomas frequently recur in the relatively short-term after surgery. We have followed such postoperative cases by short-interval repeated MRI and have performed stereotactic radiosurgery (SRS) for progressive tumors as a salvage therapy. The objective of this report was assessment of the degree of tumor control, the risk of complications, and the presence of variables that predict outcome in patients treated with SRS for high-grade meningiomas. We reviewed 12 high-grade meningioma patients with 30 lesions treated by Linac-based SRS at Kyoto University Hospital between 1997 and 2002. They included 10 atypical meningiomas and 2 anaplastic ones according to the WHO classification. A mean tumor volume was 4.40cc and a mean marginal dose of SRS was 18.0 Gy (12-20 Gy). After a mean follow-up period of 43.4 months (6-84 months), 13 lesions had progression tumor within the SRS field and 6 lesions had out of the SRS field. Nine of 14 lesions, which were treated by SRS with a marginal dose of less than 20 Gy, had local recurrence in the SRS field. In contrast, four of 16 lesions, which were treated with marginal dose of 20 Gy, had local recurrence in the SRS field. The marginal dose <20 Gy was a statistically significant factor for a short-term progression in high-grade meningiomas (P = 0.0139). Five-year progression-free survival ratio in lesions treated with SRS below 20 Gy and 20 Gy were 29.4% and 63.1%, respectively. In conclusion, based on our findings, we suggest that recurrent high-grade meningiomas be treated by SRS with a marginal dose exceeding 20 Gy.

Gamma-knife radiosurgery for cranial base meningiomas: experience of tumor control, clinical course, and morbidity in a follow-up of more than 8 years.

Zachenhofer I, Neurosurgery. 2006 Jan;58(1):28-36

Department of Neurosurgery, Medical University of Vienna, Vienna, Austria. iris.zachenhofer@meduniwien.ac.at

OBJECTIVE: Surgical resection of cranial base meningiomas is often limited owing to involvement of crucial neural structures. Within the last 2 decades Gamma Knife radiosurgery (GKRS) has gained increasing importance as an adjunct treatment after 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 cranial base meningiomas, following our previously published early follow-up experience. METHODS: A retrospective analysis of the medical files for Gamma Knife and surgical treatments, clinicoradiological findings, and outcome was carried out focusing on tumor control, clinical course, and morbidity. RESULTS: Between 1992 and 1995, we treated 36 patients with cranial base meningiomas using GKRS (male:female ratio, 1:5; mean age, 59 yr; range, 44-89 yr). Twenty-five patients were treated with GKRS after 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 mo; range, 70-133 mo) and compared with our previous results after an early follow-up period (mean, 48 mo; range, 36-76 mo). Control of tumor growth was achieved in 94% of patients. Compared with the early follow-up period, the late neuroradiological effects of GKRS on cranial base meningiomas were continuing tumor shrinkage in 11 patients (33%), stable tumor size in 20 patients (64%) and tumor progression in two meningiomas (6%). The neurological status improved in 16 patients (44%), remained stable in 19 patients (52%), and deteriorated in one patient (4%). Adverse side effects of GKRS were found only during the early follow-up period. CONCLUSION: Our data confirm that GKRS is not only a safe and effective treatment modality for cranial base meningiomas in short-term observation, but also in a mean long-term follow-up period of more than 8 years. Tumor shrinkage and clinical improvement also continued during the longer follow-up period.