Of 39 patients with a surgery background, 30 showed edema, 13 (33%) in a period greater than the median and 17 (43%) lower than the median, and this comparison was not different from the statistical viewpoint (χ 2 = 0.41; P = 0.75); notwithstanding, if we consider the average of this interval (32.4 months), the difference is marginally significant ( P = 0.05).
We considered that the high frequency of edema after RS in our patients was a result of the dose used, because, although in the univariate and multivariate analysis, the prescribed marginal dose did not reach statistical significance, more of our patients received doses greater than marginal 16 Gy and which, according to some investigators, is a significant factor linked to the development of edema after RS. 14 If the average percentage for edema is reported according to technique used, we may observe that, with GKRS, the avera