Robert M. Starke, James H. Nguyen, Jessica Rainey, Brian J. Williams, Jonathan H. Sherman, Jesse Savage, Chun Po Yen and Jason P. Sheehan
Although numerous studies have analyzed the role of stereotactic radiosurgery for intracranial meningiomas, few studies have assessed outcomes of posterior fossa meningiomas after stereotactic radiosurgery. In this study, the authors evaluate the outcomes of posterior fossa meningiomas treated with Gamma Knife surgery (GKS). The authors also assess factors predictive of new postoperative neurological deficits and tumor progression.
A retrospective review was performed of a prospectively compiled database documenting the outcomes of 152 patients with posterior fossa meningiomas treated at the University of Virginia from 1990 to 2006. All patients had a minimum follow-up of 24 months. There were 30 males and 122 females, with a median age of 58 years (range 12–82 years). Seventy-five patients were treated with radiosurgery initially, and 77 patients were treated with GKS after resection. Patients were assessed clinically and radiographically at routine intervals following GKS. Factors predictive of new neurological deficit following GKS were assessed via univariate and multivariate analysis, and Kaplan-Meier analysis and Cox multivariate regression analysis were used to assess factors predictive of tumor progression.
Patients had meningiomas centered over the tentorium (35 patients, 23%), cerebellopontine angle (43 patients, 28%), petroclival region (28 patients, 18%), petrous region (6 patients, 4%), and clivus (40 patients, 26%). The median follow-up was 7 years (range 2–16 years). The mean preradiosurgical tumor volume was 5.7 cm3 (range 0.3–33 cm3), and mean postradiosurgical tumor volume was 4.9 cm3 (range 0.1–33 cm3). At last follow-up, 55 patients (36%) displayed no change in tumor volume, 78 (51%) displayed a decrease in volume, and 19 (13%) displayed an increase in volume. Kaplan-Meier analysis demonstrated radiographic progression-free survival at 3, 5, and 10 years to be 98%, 96%, and 78%, respectively. In Cox multivariable analysis, pre-GKS covariates associated with tumor progression included age greater than 65 years (hazard ratio [HR] 3.24, 95% CI 1.12–9.37; p = 0.03) and a low dose to the tumor margin (HR 0.76, 95% CI 0.60–0.97; p = 0.03), and post-GKS covariates included shunt-dependent hydrocephalus (HR 25.0, 95% CI 3.72–100.0; p = 0.001). At last clinical follow-up, 139 patients (91%) demonstrated no change or improvement in their neurological condition, and 13 patients showed symptom deterioration (9%). In multivariate analysis, the only factors predictive of new or worsening symptoms were clival or petrous location (OR 4.0, 95% CI 1.1–13.7; p = 0.03).
Gamma Knife surgery offers an acceptable rate of tumor control for posterior fossa meningiomas and accomplishes this with a low incidence of neurological deficits. In patients selected for GKS, tumor progression is associated with age greater than 65 years and decreasing dose to the tumor margin. Clival- or petrous-based locations are predictive of an increased risk of new or worsening neurological deficit following GKS.
Brian J. Williams, Chun Po Yen, Robert M. Starke, Bhuvaneswara Basina, James Nguyen, Jessica Rainey, Jonathan H. Sherman, David Schlesinger and Jason P. Sheehan
Stereotactic radiosurgery serves as an important primary and adjuvant treatment option for patients with many types of intracranial meningiomas. This is particularly true for patients with parasellar meningiomas. In this study, the authors evaluated the outcomes of Gamma Knife surgery (GKS) used to treat parasellar meningiomas.
The study is a retrospective review of the outcomes in 138 patients with meningiomas treated at the University of Virginia from 1989 to 2006; all patients had a minimum follow-up of 24 months. There were 31 men and 107 women whose mean age was 54 years (range 19–85 years). Eighty-four patients had previously undergone resection. The mean pre-GKS tumor volume was 7.5 ml (range 0.2–54.8 ml). Clinical and radiographic evaluations were performed, and factors related to favorable outcomes in each case were assessed.
The mean follow-up duration was 84 months (median 75.5 months, range 24–216 months). In 118 patients (86%), the tumor volume was unchanged or had decreased at last follow-up. Kaplan-Meier analysis demonstrated radiographic progression-free survival at 5 and 10 years to be 95.4% and 69%, respectively. Fourteen patients (10%) developed new cranial nerve palsies following GKS. Factors associated with tumor control included younger age, a higher isodose, and smaller tumor volume. A longer follow-up duration was associated with either a decrease or increase in tumor volume. Fourteen patients (10%) experienced new or worsening cranial nerve deficits after treatment. Factors associated with this occurrence were larger pretreatment tumor volume, lower peripheral radiation dose, lower maximum dose, tumor progression, and longer follow-up.
Gamma Knife surgery offers an acceptable rate of tumor control for parasellar meningiomas and accomplishes this with a low incidence of neurological deficits. Radiological control after radiosurgery is more likely in those patients with a smaller tumor volume and a higher prescription dose.