Shuto Takashi, Matsunaga Shigeo
Department of Neurosurgery, Yokohama Rosai Hospital, Yokohama, JPN.
Cureus. 2021 Aug 5;13(8):e16901. doi: 10.7759/cureus.16901. eCollection 2021 Aug.
Introduction The effectiveness of Gamma Knife surgery (GKS) for small arteriovenous malformations (AVMs) is well known. However, for large AVMs, the prescribed dose should be decreased to reduce the risk of radiation damage, but it leads to a decrease in nidus obliteration rates. Therefore, it is very difficult to achieve complete obliteration of large AVMs in a single treatment, and methods using multiple irradiation such as volume-staged stereotactic radiosurgery (VS-SRS) have been suggested. We retrospectively reviewed our results of VS-SRS for large AVMs to assess the efficacy of VS-SRS. Methods Nineteen patients with AVMs of ≥10 ml and who consented to VS-SRS were treated by this surgical strategy and retrospectively analyzed. We excluded AVMs that were too large such as those >40 cc to avoid severe radiation damage. The components were divided mainly in the vertical direction, and each component was irradiated with a marginal dose of 18 Gy. Each irradiation was performed at intervals of 3-6 months, and the components with main feeders were irradiated first, and the components that included the main drainer were irradiated last. We tried to keep V18 to <10 ml if possible. The follow-up after GKS was performed by MRI every 6 months, and cerebral angiography was performed to confirm complete nidus obliteration, but if the patient refused, it was judged on the basis of MRI findings. Results Nineteen patients with a mean age of 40.2 years underwent VS-SRS. Each compartment was irradiated at 3--16 month (median, 3 months) intervals. The mean initial AVM volume was 19 ± 5.6 ml. Fourteen patients received two-stage radiosurgery and five received three-stage radiosurgery. The median target volume was 9.1 ml at stage 1, 9.0 ml at stage 2, and 10.1 ml at stage 3. The median margin dose was 18 Gy at each stage. The mean follow-up after the last stage of radiosurgery was 3.9 (1-11.4) years. Complete obliteration was confirmed by angiography in six patients, and by magnetic resonance angiography in one patient. The cumulative obliteration rates were 30.7% and 58.2% at 3 and 5 years following VS-SRS, respectively. The cumulative hemorrhage rates were 7.1% and 22.1% at 3 and 5 years, respectively. MRI showed T2-weighted prolongation in 15 patients (78.9%). Of these 15 patients, four were symptomatic (epilepsy in all) and two underwent surgical removal of symptomatic expanding hematomas. Conclusions In our experience, VS-SRS offers a viable treatment strategy in patients with large AVMs. Further optimization of the dose and volume at each stage is required.
引言 伽玛刀手术（GKS）治疗小型动静脉畸形（AVM）的有效性已广为人知。然而，对于大型AVM，应降低处方剂量以降低辐射损伤风险，但这会导致病灶闭塞率下降。因此，单次治疗很难实现大型AVM的完全闭塞，于是有人提出了使用多次照射的方法，如体积分期立体定向放射外科治疗（VS-SRS）。我们回顾性分析了我们采用VS-SRS治疗大型AVM的结果，以评估VS-SRS的疗效。
方法 19例AVM体积≥10 ml且同意接受VS-SRS的患者接受了该手术策略治疗，并进行回顾性分析。我们排除了那些太大的AVM，如>40 cc的，以避免严重的辐射损伤。各部分主要在垂直方向进行划分，每部分给予18 Gy的边缘剂量照射。每次照射间隔3 - 6个月，先照射有主要供血动脉的部分，最后照射包含主要引流静脉的部分。我们尽可能将V18保持在<10 ml。GKS术后每6个月进行一次MRI随访，并进行脑血管造影以确认病灶完全闭塞，但如果患者拒绝，则根据MRI结果进行判断。
结果 19例患者平均年龄40.2岁，接受了VS-SRS治疗。各部分照射间隔为3 - 16个月（中位数为3个月）。初始AVM平均体积为19 ± 5.6 ml。14例患者接受了两阶段放射外科治疗，5例接受了三阶段放射外科治疗。第1阶段的中位靶体积为9.1 ml，第2阶段为9.0 ml，第3阶段为10.1 ml。各阶段的中位边缘剂量均为18 Gy。放射外科最后阶段后的平均随访时间为3.9（1 - 11.4）年。6例患者经血管造影证实完全闭塞，1例患者经磁共振血管造影证实完全闭塞。VS-SRS后3年和5年的累积闭塞率分别为30.7%和58.2%。3年和5年的累积出血率分别为7.1%和22.1%。MRI显示15例患者（78.9%）T2加权像延长。在这15例患者中，4例有症状（均为癫痫），2例接受了有症状的扩大血肿的手术切除。
结论 根据我们的经验，VS-SRS为大型AVM患者提供了一种可行的治疗策略。需要进一步优化各阶段的剂量和体积。
