[Significance of radiosurgery for the treatment of meningiomas]. / Význam radiochirurgie v lécbe meningiomu.

Treatment of intracranial meningiomas in the light of their benignity (90%) should ensure minimal risk of recurrence, avoid new neurological deficit and preserve quality of life. Stereotactic radiosurgery has proved its long-term effectiveness and safety with a low complication rate. It can be applied as a method of choice for meningiomas in locations that are too risky for microsurgical removal, meningiomas that usually do not exceed 3 cm in diameter and in patients, who are not candidates for microsurgery because of associated disease. It is a part of multimodal treatment for recurrence after operative resection or after partial removal of large meningiomas, where radical surgery represents a high risk of postoperative morbidity and mortality. Indication of radiosurgical treatment of intracranial meningiomas should be considered for each patient individually in order to choose methods or their combination with the lowest risk of complications.

Gamma Knife surgery for benign meningioma.

OBJECT: Meningioma is the most frequent benign tumor treated with Gamma Knife surgery (GKS); however, the assessment of its efficacy and safety in slow-growing tumors is an ongoing process, requiring analysis of long-term results. METHODS: Three hundred sixty-eight patients harboring 400 meningiomas treated between 1992 and 1999 at Na Homolce Hospital were evaluated. The median patient age was 57 years (range 18-84 years). The median tumor volume was 4.4 cm3 (range 0.11-44.9 cm3). The median tumor margin dose to the 50% isodose line was 12.55 Gy (range 6.5-24 Gy). Descriptive analysis was performed in 331 patients (90%); 325 patients had a follow-up longer than 24 months (median 60 months), and six patients were included because of posttreatment complications. The volume of treated tumors decreased in 248 cases (69.7%), remained the same in 99 (27.8%), and increased in nine (2.5%). The actuarial tumor control rate was 97.9% at 5 years post-GKS. Perilesional edema after radiosurgery was confirmed on neuroimaging in 51 patients (15.4%). The temporary and permanent morbidity rates after radiosurgery were 10.2 and 5.7%, respectively. RESULTS: A significantly higher incidence of tumor volume increase was observed in men compared with women and in tumors treated with a margin dose lower than 12 Gy. Significant risk factors for edema included an age greater than 60 years, no previous surgery, perilesional edema before radiosurgery, a tumor volume greater than 10 cm3, a tumor location in the anterior fossa, and a margin dose greater than 16 Gy. CONCLUSIONS: Stereotactic radiosurgery is a safe method of treatment for meningiomas. A minimum margin dose of 12 to 16 Gy seems to represent the therapeutic window for benign meningiomas with a high tumor control rate in a mid-term follow-up period.

Prediction of intracranial edema after radiosurgery of meningiomas.

OBJECT: This study was focused on the development of models with which to predict the occurrence of intracranial edema after Gamma Knife surgery (GKS) of meningiomas, based on clinical and imaging data collected in a large group of patients. METHODS: Data in 368 patients with 381 meningiomas treated using the Leksell Gamma Knife unit were analyzed. Follow up of more than 24 months was available in 331 patients (90%); this time period ranged from 24 to 120 months (median 51 months). The actuarial tumor control rate was 97.9% at 5 years. Perilesional edema after GKS was radiologically confirmed in 51 patients (15.4%) and 32 of them (9.7%) were symptomatic; symptoms were temporary in 23 (6.9%) and permanent in nine (2.7%). Ten different factors were proposed as potential predictors for the occurrence of the intracranial edema after GKS: patient's sex, patient's age, previous surgery, edema before GKS treatment, lobulated margin of meningioma, heterogeneous appearance of the tumor, tumor volume, tumor location, maximum dose to the tumor, and dose to the tumor margin. To identify factors having influence on edema occurrence, univariate and multivariate statistical analyses were performed. There was a significant difference in the incidence of edema for different patient age groups and a significantly higher incidence of edema occurrence in patients in whom no surgical procedure was performed before GKS, those with edema present before GKS, those with a tumor volume larger than 10 cm3, those in whom the tumor was located in the anterior fossa, those in whom the maximum dose to the tumor was higher than 30 Gy, and for different tumor margin doses. A binary logistic regression multifactorial prediction model was used to identify the following significant factors to predict of edema occurrence after GKS: previous surgery, edema before the treatment, tumor volume, tumor location, and tumor margin dose. CONCLUSIONS: Based on these models estimates of the occurrence of edema after the GKS can be made, and consequently treatment parameters can be adjusted to reduce the occurrence of edema. These results may provide grounds for additional patient care such as more frequent follow up or possibly administration of steroids.