1Gamma Knife Center, Chang Bing Show Chwan Memorial Hospital.
4Department of Internal Medicine, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California.
J Neurosurg. 2018 May;128(5):1380-1387. doi: 10.3171/2016.12.JNS161530. Epub 2017 Jul 14.
OBJECTIVE Stereotactic radiosurgery (SRS) is an important alternative management option for patients with small- and medium-sized vestibular schwannomas (VSs). Its use in the treatment of large tumors, however, is still being debated. The authors reviewed their recent experience to assess the potential role of SRS in larger-sized VSs. METHODS Between 2000 and 2014, 35 patients with large VSs, defined as having both a single dimension > 3 cm and a volume > 10 cm, underwent Gamma Knife radiosurgery (GKRS). Nine patients (25.7%) had previously undergone resection. The median total volume covered in this group of patients was 14.8 cm (range 10.3-24.5 cm). The median tumor margin dose was 11 Gy (range 10-12 Gy). RESULTS The median follow-up duration was 48 months (range 6-156 months). All 35 patients had regular MRI follow-up examinations. Twenty tumors (57.1%) had a volume reduction of greater than 50%, 5 (14.3%) had a volume reduction of 15%-50%, 5 (14.3%) were stable in size (volume change < 15%), and 5 (14.3%) had larger volumes (all of these lesions were eventually resected). Four patients (11.4%) underwent resection within 9 months to 6 years because of progressive symptoms. One patient (2.9%) had open surgery for new-onset intractable trigeminal neuralgia at 48 months after GKRS. Two patients (5.7%) who developed a symptomatic cyst underwent placement of a cystoperitoneal shunt. Eight (66%) of 12 patients with pre-GKRS trigeminal sensory dysfunction had hypoesthesia relief. One hemifacial spasm completely resolved 3 years after treatment. Seven patients with facial weakness experienced no deterioration after GKRS. Two of 3 patients with serviceable hearing before GKRS deteriorated while 1 patient retained the same level of hearing. Two patients improved from severe hearing loss to pure tone audiometry less than 50 dB. The authors found borderline statistical significance for post-GKRS tumor enlargement for later resection (p = 0.05, HR 9.97, CI 0.99-100.00). A tumor volume ≥ 15 cm was a significant factor predictive of GKRS failure (p = 0.005). No difference in outcome was observed based on indication for GKRS (p = 0.0761). CONCLUSIONS Although microsurgical resection remains the primary management choice in patients with VSs, most VSs that are defined as having both a single dimension > 3 cm and a volume > 10 cm and tolerable mass effect can be managed satisfactorily with GKRS. Tumor volume ≥ 15 cm is a significant factor predicting poor tumor control following GKRS.
目的
立体定向放射外科（SRS）是治疗小中型前庭神经鞘瘤（VSs）的重要替代治疗方法。然而，其在大型肿瘤治疗中的应用仍存在争议。作者回顾了他们的近期经验，以评估 SRS 在较大 VSs 中的潜在作用。
方法
2000 年至 2014 年间，35 名大型 VS 患者（定义为单一维度>3cm 和体积>10cm）接受了伽玛刀放射外科治疗（GKRS）。9 名患者（25.7%）曾接受过切除术。该组患者的中位总覆盖体积为 14.8cm（范围 10.3-24.5cm）。肿瘤边缘剂量中位数为 11Gy（范围 10-12Gy）。
结果
中位随访时间为 48 个月（范围 6-156 个月）。所有 35 名患者均进行了定期 MRI 随访检查。20 个肿瘤（57.1%）体积减少>50%，5 个肿瘤（14.3%）体积减少 15%-50%，5 个肿瘤（14.3%）体积稳定（体积变化<15%），5 个肿瘤（14.3%）体积增大（所有这些病变最终均被切除）。4 名患者（11.4%）因症状进展在 9 个月至 6 年内接受了切除术。1 名患者（2.9%）在 GKRS 后 48 个月因新发性难治性三叉神经痛而行开颅手术。2 名出现症状性囊肿的患者行囊肿腹腔分流术。GKRS 前 12 名三叉神经感觉功能障碍患者中有 8 名（66%）感觉减退缓解。1 例面肌痉挛完全缓解 3 年后。GKRS 后 7 名面部无力患者无恶化。3 名术前有可利用听力的患者中有 2 名恶化，1 名患者听力相同。2 名患者从严重听力损失改善至纯音听阈小于 50dB。作者发现肿瘤增大与术后切除（p=0.05，HR 9.97，CI 0.99-100.00）存在边缘统计学意义。肿瘤体积≥15cm 是 GKRS 失败的显著预测因素（p=0.005）。根据 GKRS 的适应证，结果无差异（p=0.0761）。
结论
尽管显微切除术仍然是 VSs 患者的主要治疗选择，但大多数定义为单一维度>3cm 和体积>10cm 且可耐受肿块效应的 VSs 都可以通过 GKRS 得到满意的治疗。肿瘤体积≥15cm 是 GKRS 后肿瘤控制不良的显著预测因素。
