OBJECTIVES Initially treating vestibular schwannomas (VSs) with subtotal resection (STR) followed by Gamma Knife radiosurgery (GKRS) for progression of tumor residual is a strategy that balances maximal tumor resection with preservation of neurological function. The effect of timing of GKRS for residual and recurrent VSs remains poorly defined. We developed a simple and practical treatment algorithm for the timing of GKRS after STR of VSs and reviewed our follow-up results to determine outcomes between patients treated with early vs. late GKRS. PATIENTS AND METHODS Patients that underwent STR between 1999 and 2017 for a VS at Tufts Medical Center were identified and included in the study cohort. Patients who received GKRS ≤ 12 months after STR were included in the early intervention group. Patients who received GKRS > 12 months after STR or did not have tumor progression on follow-up thus not requiring GKRS were included in the observation/delayed intervention group. RESULTS STR of VSs was performed on 23 patients. Mean patient age at the time of STR was 53.0 years (range: 20-86.2). The mean follow-up was 4.2 years (range: 1 month-15.5 years). Patients most frequently presented with hearing loss. There were 5 patients (21.7 %) in the early intervention group and 18 (78.3 %) patients in the observation/delayed intervention group. Ten of 23 patients (43.5 %) required GKRS. Thirteen (56.5 %) did not receive GKRS. None of the patients in the early intervention group or the observation/delayed intervention group had changes in House-Brackmann (HB) Grade either after GKRS or at the end of the study period. CONCLUSIONS GKRS of residual or recurrent tumor is safe following STR of VS and appears to carry a low risk of worsening facial nerve function when performed for progressive tumor growth.

中文翻译：

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伽马刀放射外科手术治疗前庭神经鞘瘤次全切除后的面神经结果：早期与延迟治疗时机

目标 首先用次全切除术 (STR) 治疗前庭神经鞘瘤 (VSs)，然后用伽玛刀放射外科 (GKRS) 治疗肿瘤残留的进展，这是一种在最大程度切除肿瘤和保留神经功能之间取得平衡的策略。GKRS 时间对残余和复发性 VS 的影响仍然不明确。我们开发了一种简单实用的治疗算法，用于 VS STR 后 GKRS 的时间安排，并回顾了我们的随访结果，以确定接受早期与晚期 GKRS 治疗的患者之间的结果。患者和方法 1999 年至 2017 年间在塔夫茨医学中心接受 STR 治疗的患者被确定并纳入研究队列。STR 后 ≤ 12 个月接受 GKRS 的患者被纳入早期干预组。接受 GKRS 的患者 > STR 后 12 个月或在随访中没有肿瘤进展因此不需要 GKRS 被包括在观察/延迟干预组中。结果 对 23 名患者进行了 VS 的 STR。STR 时患者的平均年龄为 53.0 岁（范围：20-86.2）。平均随访时间为 4.2 年（范围：1 个月至 15.5 年）。患者最常出现听力损失。早期干预组有 5 名患者 (21.7 %)，观察/延迟干预组有 18 名患者 (78.3 %)。23 名患者中有 10 名 (43.5 %) 需要 GKRS。13 人 (56.5 %) 未收到 GKRS。早期干预组或观察/延迟干预组中的患者在 GKRS 后或研究期结束时均未出现 House-Brackmann (HB) 等级变化。