RISK FACTORS ASSOCIATED WITH STEREOTACTIC RADIOSURGERY FOR LARGE SKULL BASE BENIGN MENINGIOMAS

Abstract

Purpose Skull base meningiomas represent a very challenging pathology due to relatively difficult surgical access. In contrast, stereotactic radiosurgery (SRS) proved to be an effective and more secure treatment technique based on the greater accuracy in delivering precise focused radiation into the target, sparing at the same time healthy surrounding tissues. Methods and Results Our study, based on almost 20 years of experience in delivering SRS treatments using various models of Leksell Gamma-Knife units, reports a high tumor control rate for complex-shaped skull base meningiomas close to critical structures. We retrospectively evaluated the risk factors and complications after high-dose irradiation in patients undergoing single-fraction radiosurgery combined with clinical imaging criteria established using MRI scans (in T1 weighted imaging with gadolinium and the edema in T2 weighted sequences). The mean volume of the tumors was 18.6 cubic centimetres (only tumors with a volume in excess of 15 cubic centimetres were included in the study). The median administered marginal dose was 12.5 Gy. Mean imaging follow-up was 112 months. Tumor control rate was not influenced by sex, age, tumor site, neurological status of the patient or irradiated volume, even though larger meningiomas are associated with poor long-term local control in most published series. The long-term follow-up data indicates tumor control in 88,5% of patients after 10 years, with low incidence of complications. Conclusions Current practice shows a slight potential increase in the incidence of meningiomas, the superiority of the individual techniques needing to be confirmed in prospective and methodologically rigorous studies with at least 20 years of follow-up.

Keywords

• skull base
• meningiomas
• risk factors
• stereotactic radiosurgery (SRS)