射波刀治疗听神经瘤的初步结果

目的 总结射波刀分次治疗听神经瘤的初步结果和设计治疗计划技巧.方法 应用射波刀分次治疗29例听神经瘤.肿瘤平均最大直径为31 mm.肿瘤平均体积为13.2 cm3 (0.3～36.0 cm3).设计治疗计划时,将射线束控制在150～ 200条之间,使治疗计划有良好的适形性,同时提高肿瘤内高剂量区范围.2例巨大肿瘤照射4次,3例小肿瘤照射2次,其余24例照射3次.平均随访时间21个月.结果 1例巨大肿瘤患者在治疗后10个月死亡,其余28例肿瘤中,6例缩小50％以上,15例缩小20％,7例肿瘤无变化.13例保持原有有效听力,1例听力明显下降,1例听力从无效改善为有效,其余患者为无效听力.无面瘫,3例患者出现脑积水,1例出现脑干水肿,治疗后水肿消失.结论 射波刀分次治疗听神经瘤的初步疗效满意,不良反应较轻；为高龄、不适合手术、部分肿瘤较大的听神经瘤患者提供又一治疗手段,但长期疗效和不良反应有待进一步随访.

Multi -session cyberknife for patients with vestibular schwannomas: preliminary outcomes

Objective To evaluate the preliminary outcomes in patient with vestibular schwannomas treated using multi - session cyberknife radiosurgery and introduce personal experience in treatment planning.Methods From December 2007 to February 2010,29 patients with vestibular schwannomas,their tumor diameter was 11 ～47 mm,were treated by cyberknife in our center.Twenty -six patients were diagnosed by MRI and cyberknife were primary treatment modality for them.Three patients had residual tumor.Three patients with bilateral vestibular schwannomas was neurofibromatosis Type 2.The tumor volume ranged from 0.3 to 36.0 cm3 ( mean,13.2 ±4.7 cm3 ),17 of them was more than 10 cm3 in volume.The radiation dose prescribed to the tumor margin of two giant tumors was 22 Gy and 22.8 Gy respectively in 4 fractions,the tumor margin dose of three small tumors was 16.8 Gy,17.4 Gy and 17.4 Gy respectively in 2 fractions.The margin dose of the rest 24 tumors ranged from 15.0 Gy to 21.0 Gy (mean,19.2 Gy) in 3 fractions.In treatment planning process,the author selected 65％ to 70％ isodose line to cover the tumor margin and the beam number was controlled between 150 and 200 to make the treatment planning more conformal and more higher dose volume within tumors.The mean duration of follow up was 21 months(range:14 - 38 months).Results One patient (77 years old) with giant tumor was deceased at 10 months post cyberkinfe because tumor swelling and medical condition,the rest 28 patients had normal life.Thirteen (92％) of 14 patients with serviceable hearing before cyberknife preserved serviceable hearing after cyberknife.One patient with non - serviceable hearing had improvement hearing at 1 year and recovered serviceable hearing at 2 year after cyberknife.Six patients developed temporary facial numbness and improved later.One patient with large residual tumor developed slight facial palsy at 12 months post cyberknife and recovered 5 month later.Three patients ( 10％ ) developed hydrocephalus at about 12 months post cyberknife and 2 of them underwent a ventriculoperitoneal shunt.One patient with both vestibular and trigeminal schwannomas developed brain stem edema at 9 months because of irradiating two tumors at same time and some area of higher irradiation dose within brain stem.The edema disappeared 3 months later after administration of mannitol and dexamethasone.In 28 patients alive,tumor volume decreased more than 50％ in 6 patients,decreased more than 20％ in 15 patients.Seven tumors kept stable.In this ~ries tumor control rate was 96％ (28/29).Conclusion Multi -session cyberknffe is an effective treatment for patient with small - and medium- sized vestibular schwannomas,and some patients with large vestibular schwannomas,who had contraindications for open surgery,but long- term follow-up is needed.