Romanelli Pantaleo, Bianchi Livia, Muacevic Alexander, Beltramo Giancarlo
CyberKnife Center, Centro Diagnostico Italiano, Milan, Italy.
Comput Aided Surg. 2011;16(6):257-66. doi: 10.3109/10929088.2011.622615.
Optic nerve sheath meningiomas (ONSMs) represent the most challenging lesions involving the optic pathways: Microsurgery is not indicated and classical single-stage radiosurgery appears to be too risky due to the expected destruction of the common blood supply with consequent loss of vision. Staged radiosurgery might be one treatment option because it exploits the ability of normal tissues to repair sub-lethal radiation-induced damage, offering a chance to control tumor growth while sparing function. Staged robotic radiosurgery was offered to 5 patients harboring ONSMs with the aim of sparing vision while achieving local growth control.
Five patients with ONSM presenting with visual field deficits and loss of visual acuity were treated with staged CyberKnife radiosurgery, receiving 20 Gy in 4 stages (5 Gy per stage). Treatment planning was based on contrast-enhanced thin-slice CT (1.25 mm thickness for the first three cases, 0.5 mm for the last two) and volumetric MR imaging (1.5 T for the first three cases, 3 T for the last two). An interval of 24 hours was strictly observed between stages. Visual acuity and visual fields were assessed in all patients immediately prior to treatment and at intervals of 6 months thereafter. Follow-up MRIs were performed every 6 months for 2 years, then once per year.
The entire procedure, inclusive of imaging, treatment planning and treatment delivery, was performed in 5 days. Irradiation required approximately 45 min per stage. Mean tumor volume was 2.94 cc (range: 0.8-6.4 cc). Treatment was well tolerated in all patients. Follow-up ranged from 36 to 74 months. Local growth control was achieved in all patients. Restoration of normal vision was experienced by 4 patients 6 to 12 months after the treatment. One patient, who was also affected by diabetic retinopathy, showed a modest improvement after 6 months, remaining stable thereafter.
Staged CyberKnife radiosurgery provides a fast and well-tolerated non-invasive treatment with excellent visual outcomes. If these preliminary results are confirmed by larger series, staged radiosurgery could be proposed as a first-line treatment for ONSM.
视神经鞘膜瘤（ONSM）是累及视神经通路最具挑战性的病变：显微手术并不适用，而经典的单阶段放射外科手术似乎风险过高，因为预期会破坏共同血供，进而导致视力丧失。分阶段放射外科手术可能是一种治疗选择，因为它利用了正常组织修复亚致死性辐射诱导损伤的能力，提供了在保留功能的同时控制肿瘤生长的机会。对5例患有ONSM的患者进行了分阶段机器人放射外科手术，目的是在实现局部生长控制的同时保留视力。
对5例出现视野缺损和视力丧失的ONSM患者进行了分阶段的射波刀放射外科手术，分4个阶段接受20 Gy（每个阶段5 Gy）。治疗计划基于增强薄层CT（前三例厚度为1.25 mm，后两例为0.5 mm）和容积性磁共振成像（前三例为1.5 T，后两例为3 T）。各阶段之间严格遵守24小时的间隔。在所有患者治疗前及之后每6个月对视力和视野进行评估。随访MRI每6个月进行一次，共2年，然后每年进行一次。
整个过程，包括成像、治疗计划和治疗实施，在5天内完成。每个阶段的照射大约需要45分钟。平均肿瘤体积为2.94 cc（范围：0.8 - 6.4 cc）。所有患者对治疗耐受性良好。随访时间为36至74个月。所有患者均实现了局部生长控制。4例患者在治疗后6至12个月视力恢复正常。1例同时患有糖尿病视网膜病变的患者在6个月后有适度改善，此后保持稳定。
分阶段射波刀放射外科手术提供了一种快速且耐受性良好的非侵入性治疗方法，视觉效果极佳。如果这些初步结果得到更大规模系列研究的证实，分阶段放射外科手术可被提议作为ONSM的一线治疗方法。
