Department of Neurosurgery, Gamma Knife Center, Komaki City Hospital, Komaki, Japan.
J Neurosurg. 2011 Dec;115(6):1078-86. doi: 10.3171/2011.7.JNS11749. Epub 2011 Aug 26.
Gamma Knife surgery (GKS) has been a safe and effective treatment for small- to medium-sized vestibular schwannomas (VSs) over relatively long-term outcomes. However, even with recent radiosurgical techniques, hearing results following GKS remain unsatisfactory. The purpose of this study was to evaluate the hearing preservation rate as well as factors related to hearing preservation in patients with VSs and serviceable hearing who were treated with GKS.
Among patients with Gardner-Robertson (GR) Class I or II serviceable hearing and VSs treated with GKS between 1991 and 2009, 117 were evaluable via periodic MR imaging and audiometry.
The median age at the time of GKS was 52 years. Four patients (3%) had undergone prior surgery. Fifty-six patients (48%) had GR Class I hearing and 61 (52%) had GR Class II hearing at the time of GKS. The median tumor volume was 1.9 cm(3). The median maximum and tumor margin radiation doses were 24 and 12 Gy, respectively. The median follow-up periods for MR imaging and audiometry were 74 and 38 months, respectively. The overall tumor control rate was 97.5%. Actuarial 3-, 5-, and 8-year hearing preservation rates were 55%, 43%, and 34%, respectively. On multivariate analysis, GR hearing class at the time of GKS and the mean cochlear dose affected hearing preservation significantly. In a limited number of patients who were treated using the most recent dose planning techniques and who had GR Class I hearing before treatment, the 3- and 5-year hearing preservation rates increased to 80% and 70%, respectively.
For the majority of patients with small- to medium-sized VSs, GKS was an effective and reasonable alternative to resection with satisfactory long-term tumor control. Factors related to hearing preservation included a GR Class I hearing pre-GKS and a lower mean cochlear radiation dose. To retain serviceable hearing, it is important to apply GKS treatment while patients retain GR Class I hearing.
伽玛刀手术（GKS）在相对长期的结果中已成为治疗中小型前庭神经鞘瘤（VSs）的安全有效方法。但是，即使采用最近的放射外科技术，GKS 后的听力结果仍不理想。本研究的目的是评估保留听力的比率以及具有服务性听力的 VS 患者接受 GKS 治疗时与保留听力相关的因素。
在 1991 年至 2009 年间接受 GKS 治疗且具有 Gardner-Robertson（GR）I 级或 II 级可利用听力的 VS 患者中，有 117 例通过定期磁共振成像和测听进行评估。
GKS 时的中位年龄为 52 岁。4 例（3％）患者曾接受过手术。GKS 时，56 例（48％）患者具有 GR 听力 I 级，61 例（52％）患者具有 GR 听力 II 级。肿瘤体积中位数为 1.9cm3。最大肿瘤和肿瘤边缘剂量的中位数分别为 24 和 12Gy。磁共振成像和测听的中位随访时间分别为 74 和 38 个月。总体肿瘤控制率为 97.5％。GKS 后 3、5 和 8 年的听力保留率分别为 55％、43％和 34％。多变量分析显示，GKS 时的 GR 听力分级和耳蜗平均剂量对听力保留有显著影响。在使用最新剂量规划技术治疗且治疗前具有 GR 听力 I 级的少数患者中，3 年和 5 年的听力保留率分别提高到 80％和 70％。
对于大多数患有中小型 VSs 的患者，GKS 是一种有效的替代手术方法，具有令人满意的长期肿瘤控制效果。与听力保留相关的因素包括 GKS 前的 GR 听力 I 级和较低的耳蜗平均辐射剂量。为了保留可利用的听力，重要的是在患者保留 GR 听力 I 级时应用 GKS 治疗。
