伽玛刀治疗脑干动静脉畸形的中长期疗效及其影响因素分析

Gamma knife radiosurgery for brainstem arteriovenous malformation： Mid-to long-term follow-up study of clinical result and related influencing factors

目的探讨伽玛刀治疗脑干动静脉畸形（AVMs）的中长期疗效及其影响因素。方法回顾性纳人1995年1月至2011年12月首都医科大学，北京市神经外科研究所伽玛刀中心采用伽玛刀治疗的脑干AVMs患者，共57例。病灶位于中脑38例，脑桥15例，延髓4例；治疗体积为0．1～22．4cm^3（中位数为1．1cm^3）；边缘处方剂量为12～20Gy，平均（15．0±1．5）Gy。8例行二次伽玛刀治疗。评价远期疗效及影响单次治疗效果的相关因素。结果57例患者治疗后临床中位随访时间为67个月（12-192个月，4例〈24个月）。49例（86．0％）神经功能缺损症状较术前无加重（11例改善，38例无改变），8例（14．O％）加重；2例（3．5％）发生永久性放射相关并发症；8例（14．0％）患者治疗后再出血11例次，治疗后年出血率为4．0％。经MRI证实，31例（54．3％）畸形血管闭塞[中位闭塞时间为35（12-72）个月]；8例畸形血管巢消失，但仍见引流静脉显影；18例畸形团残留。治疗后3、5、10年畸形血管闭塞率分别为44．2％（19／43）、75．0％（27／36）、80．0％（28／35）。多因素Cox回归分析显示，病灶位置（脑干浅表与脑干实质）（HR=2．268，95％C1：1．032～4．983，P=0．042）、体积（≤2cm^3与〉2cm^3）（HR=1．360，95％CI：1．016～1．773，P=0．039）是影响疗效的独立因素。结论伽玛刀治疗脑干AVMs是一种安全有效的治疗手段，在畸形血管完全闭塞之前，患者仍有再次出血的风险。位于脑干浅表、较小体积的AVMs疗效相对较好。

Objective To evaluate the mid-to long-term effect of gamma knife radiosurgery （GKS） for the treatment of brainstem arteriovenous malformations （AVMs） and to analyze its related influencing factors. Methods We retrospectively studied 57 patients with brainstem AVMs undergoing GKS between 1995 -2011 at Beijing Neurosurgical Institute Gamma Knife Center. The lesions were located in midbrain in 38 cases, pons in 15 cases and medulla oblongata in 4 cases. The treatment volume was 0. 1 - 22.4 cm^3 （ median： 1.1 cm^3 ）. The marginal prescription dose was 12 - 20 Gy （mean ： 15.0 ±1.5 Gy）. After the initial Gamma procedure, 8 patients had a second treatment of GKS for AVM residuals. Investigation was conducted on the long-term effect and related influencing factors of single treatment result. Results A total of 57 patients recieved clinical follow-up ranging from 12 to 192 months （median： 67 months）. There were 49 patients who showed improvement or remained stable based on modified Rankin scale. Permanent neurological deficits due to adverse radiation effects （AREs） developed in 2 （3.5%） patients post treatment. Eight （ 14. 0% ） patients experienced 11 times of hemorrhage post treatment. The overall annual hemorrhage rate was 4. 0%. Obliteration of the AVMs was eventually documented in 31 patients base on MRI result at a median of 35 months （ range ： 12 - 72 months）, subtotal obliteration in 8 and residual in 18. The rates of documentation of total obliteration were 44. 2% （ 19/43）, 75.0% （27/36） and 80.0% （28/35） at 3,5 and 10 years post surgery, respectively. Multivariate analysis revealed that the location in brainstem （superficial/deep, FIR =2. 268, 95% CI： 1. 032 -4. 983, P =0. 042） and smaller volume of AVMs （ ≤2 cm^3/〉2 cm^3, HR = 1. 360, 95% CI： 1. 016 - 1. 773, P =0. 039） was associated with a higher rate of total obliteration on MR imaging. Conclusions Gamma knife seems safe and effective for treatment of brainstem AVMs. Patients might remain at risk during the latency period until obliteration was achieved. The small volume and superficial lesions are associated with relatively better results.