Gamma Knife Unit, Division of Neurosurgery, University Health Network, Toronto, Canada.
Int J Radiat Oncol Biol Phys. 2012 Apr 1;82(5):2041-6. doi: 10.1016/j.ijrobp.2011.02.017. Epub 2011 Apr 29.
To define clinical and dosimetric predictors of nonauditory adverse radiation effects after radiosurgery for vestibular schwannoma treated with a 12 Gy prescription dose.
We retrospectively reviewed our experience of vestibular schwannoma patients treated between September 2005 and December 2009. Two hundred patients were treated at a 12 Gy prescription dose; 80 had complete clinical and radiological follow-up for at least 24 months (median, 28.5 months). All treatment plans were reviewed for target volume and dosimetry characteristics; gradient index; homogeneity index, defined as the maximum dose in the treatment volume divided by the prescription dose; conformity index; brainstem; and trigeminal nerve dose. All adverse radiation effects (ARE) were recorded. Because the intent of our study was to focus on the nonauditory adverse effects, hearing outcome was not evaluated in this study.
Twenty-seven (33.8%) patients developed ARE, 5 (6%) developed hydrocephalus, 10 (12.5%) reported new ataxia, 17 (21%) developed trigeminal dysfunction, 3 (3.75%) had facial weakness, and 1 patient developed hemifacial spasm. The development of edema within the pons was significantly associated with ARE (p = 0.001). On multivariate analysis, only target volume is a significant predictor of ARE (p = 0.001). There is a target volume threshold of 5 cm3, above which ARE are more likely. The treatment plan dosimetric characteristics are not associated with ARE, although the maximum dose to the 5th nerve is a significant predictor of trigeminal dysfunction, with a threshold of 9 Gy. The overall 2-year tumor control rate was 96%.
Target volume is the most important predictor of adverse radiation effects, and we identified the significant treatment volume threshold to be 5 cm3. We also established through our series that the maximum tolerable dose to the 5th nerve is 9 Gy.
确定接受 12 Gy 处方剂量放射外科治疗后前庭神经鞘瘤患者出现非听觉不良放射性副作用的临床和剂量学预测因素。
我们回顾性分析了 2005 年 9 月至 2009 年 12 月期间接受治疗的前庭神经鞘瘤患者的经验。200 例患者接受 12 Gy 处方剂量治疗；80 例患者接受了至少 24 个月（中位数 28.5 个月）的完整临床和放射学随访。所有治疗计划都针对靶区和剂量学特征、梯度指数、均匀性指数（定义为治疗体积中的最大剂量除以处方剂量）、适形指数、脑干和三叉神经剂量进行了审查。记录了所有不良反应（ARE）。由于我们研究的目的是关注非听觉不良反应，因此本研究未评估听力结果。
27 例（33.8%）患者出现 ARE，5 例（6%）出现脑积水，10 例（12.5%）出现新的共济失调，17 例（21%）出现三叉神经功能障碍，3 例（3.75%）出现面部无力，1 例出现面肌痉挛。桥脑内水肿的发生与 ARE 显著相关（p = 0.001）。多变量分析显示，只有靶区体积是 ARE 的显著预测因素（p = 0.001）。当靶区体积超过 5 cm3 时，ARE 更有可能发生。治疗计划的剂量学特征与 ARE 无关，尽管第 5 神经的最大剂量是三叉神经功能障碍的显著预测因素，阈值为 9 Gy。总的 2 年肿瘤控制率为 96%。
靶区体积是不良放射性效应的最重要预测因素，我们确定了 5 cm3 的显著治疗体积阈值。我们还通过我们的系列研究确定，第 5 神经的最大耐受剂量为 9 Gy。
