Long-term results of gamma radiosurgery for skull base meningiomas

The effects of gamma radiosurgery on 106 out of 150 cases of skull base meningiomas which had been treated by gamma knife and followed-up for more than 3 years (mean of 48.2 months) have been evaluated. Overall results showed that partial response (PR) was found in 44 cases, minor response (MR) in 9, no change (NC) in 42 and progression (PG) in 11. Another words, response rate was 41.5%, control rate was 89.6% and progression rate was 10.4%. There found differences of the response among different locations; the response rate of cerebello-pontine (C-P) angle and cavernous sinus (CS)-parasellar meningiomas showed higher than others, but control rate was higher in C-P angle and tentorial meningioma. Progression was found only in CS-parasellar and petroclival meningioma. The progression rate has changed from 0% at less than 3 years of follow-up, 10.4% at more than 3 years and 18.2% at more than 5 years. The factors related to the progression are the tumor size, the radiation dosis, the locations and the tumor pathology. Side effects were found in 4 cases (4.6%), that is radiation induced edema in one, hearing deterioration in two and visual deterioration in one case within 2 years of treatment. (author)