Preliminary report of multisession gamma knife radiosurgery for benign perioptic lesions: Visual outcome in 22 patients

Objective : Radiosurgery may be contraindicated for lesions adjacent to the optic pathways because of the substantial risk of visual complication. Multisession radiosurgery has been tried as a compromise between single session radiosurgery and fractionated radiotherapy. The purpose of this study is to evaluate the outcomes of multisession gamma knife radiasurgery (GKRS) in 22 patients with perioptic lesions of benign pathology. Methods : In all 22 cases, the lesions were within 1 mm of the optic apparatus and were therefore not considered suitable for single session radiosurgery. Radiation was delivered in 3 to 4 fractions with a median cumulated marginal dose of 20 Gy (range, 15-20 Gy). Results : During a mean follow-up of 29 months (range, 14-44 months), tumor control was achieved in 21 patients. Visual function improved in 7 patients, remained unchanged in 14 patients, and deteriorated in 1 patient with tumor progression. No other complication was observed. Conclusion : This preliminary result supports the idea that multisession GKRS may be an effective and safe alternative for treatment in perioptic lesions that are unsuitable for single session radiosurgery.