Bowden Greg, Cavaleri Jonathon, Monaco Edward, Niranjan Ajay, Flickinger John, Lunsford L Dade
Department of Neurological Surgery, Pittsburgh, Pennsylvania.
Center for Image-Guided Neurosurgery, University of Pittsburgh School of Medicine, Pittsburgh, Penn-sylvania.
Neurosurgery. 2017 Sep 1;81(3):490-497. doi: 10.1093/neuros/nyx027.
Vestibular schwannomas (VS) have a well-documented response to Gamma Knife® (Elekta AB, Stockholm, Sweden) Stereotactic radiosurgery (SRS). However, there are limited data available regarding the volumetric response of cystic tumors.
This report correlates the radiographic appearance of VS before radiosurgery with the delayed volumetric response.
This study reviewed our SRS experience with 219 VS patients between 2003 and 2013. Patients were treatment naïve and had a significant extracanalicular tumor volume. Magnetic resonance imaging at the time of SRS identified 42 contrast-enhancing macrocystic tumors, 45 contrast-enhancing microcystic tumors, and 132 homogeneously enhancing tumors with no intratumoral cyst formation. The median follow-up was 49.1 months. The median tumor volume was 2.6 cm 3 (0.70-16.1 cm 3 ) and the median dose was 12.5 Gy (11-13 Gy).
The actuarial tumor control rate was 99.4% at 2 years and 96.4% at 5 years. A volumetric reduction of >20% occurred in 85.4% of macrocystic tumors, 76.1% of microcystic tumors, and 62.8% of homogeneously enhancing VS. The median volume decrease per year for macrocystic, microcystic, and homogenous tumors was 17.2%, 7.5%, and 7.9% per year respectively ( P < .001). A 2:1 blinded volumetric case match showed a significant size reduction in macrocystic tumors compared to noncystic tumors ( P = .007). Serviceable hearing was maintained in 61.5% of patients that had Gardner-Robertson grade I-II hearing before treatment. Surgical resection or repeat radiosurgery was performed in 8 patients (3.6%) who had sustained tumor progression.
SRS provided VS tumor control in >95% of patients, regardless of radiographic characteristics. Tumor volume regression was most evident in patients with cystic tumors.
前庭神经鞘瘤（VS）对伽玛刀®（瑞典斯德哥尔摩的医科达公司）立体定向放射外科治疗（SRS）的反应已有充分记录。然而，关于囊性肿瘤体积反应的数据有限。
本报告将放射外科治疗前VS的影像学表现与延迟体积反应相关联。
本研究回顾了我们在2003年至2013年间对219例VS患者的SRS治疗经验。患者均为初治患者，且有显著的管外肿瘤体积。SRS时的磁共振成像识别出42例对比增强大囊性肿瘤、45例对比增强微囊性肿瘤和132例无瘤内囊肿形成的均匀强化肿瘤。中位随访时间为49.1个月。中位肿瘤体积为2.6 cm³（0.70 - 16.1 cm³），中位剂量为12.5 Gy（11 - 13 Gy）。
2年时的精算肿瘤控制率为99.4%，5年时为96.4%。85.4%的大囊性肿瘤、76.1%的微囊性肿瘤和62.8%的均匀强化VS体积缩小>20%。大囊性、微囊性和均匀性肿瘤每年的中位体积减少分别为17.2%、7.5%和7.9%（P <.001）。一项2:1的双盲体积病例匹配显示，与非囊性肿瘤相比，大囊性肿瘤的大小有显著减小（P = 0.007）。治疗前Gardner-Robertson分级为I-II级听力水平的患者中，61.5%的患者听力得以保留。8例（3.6%）肿瘤持续进展的患者接受了手术切除或重复放射外科治疗。
无论影像学特征如何，SRS在>95%的患者中实现了VS肿瘤控制。肿瘤体积退缩在囊性肿瘤患者中最为明显。
