Acta Neurochir (Wien). 2013 Dec;155(12):2273-9; discussion 2279. doi: 10.1007/s00701-013-1891-x.
Second surgery of recurrent vestibular schwannoma (VS) after previous surgery, stereotactic radiosurgery (SR) or fractionated radiotherapy (FR) carries an increased risk for deterioration of facial nerve function, e.g., due to adhesions, underlining the need for intraoperative monitoring. Facial “Atrain” EMG activity (“traintime”) correlates with the degree of postoperative facial palsy. Studies investigating A-trains in VS patients with previous surgery, SR or FR are missing. We therefore investigated the value of A-train monitoring in patients undergoing second surgery for VS.
Intraoperative EMG data from patients who underwent second surgery for VS after previous surgery, SR and/or FR at our institution between 2006 and 2012 were retrospectively analyzed. Ten patients were selected (5 male): Seven had previous SR/RT and MS, three previous surgery only. Traintime values and distribution was compared to published thresholds and to 77 patients who underwent first surgery for VS during the same time period.
A-trains were recorded early after opening of the dura, before facial nerve preparation. Mean traintime was 46.9 s (18.51 s – 80.82 s) in patients with previous SR/RT. In patients with previous MS only, traintime was 0.06 s, 0.99 s and 22.46 s. Compared to the literature, traintime was higher than expected in six patients (four with previous SR/RT, two without), respectively seven compared to the 77 patients with first surgery (5 SR/RT). Seven patients with previous SR/RT and none with previous surgery showed diffuse A-train distributions without significant percentages in single channels, compared to 60 of 77 patients with first surgery (p <0.02).
Especially SR/RT, but also previous surgery seems to induce changes in the facial nerve leading to hyperexcitability and exceedingly high traintime values. Based on these findings, A-train monitoring in this specific patient group should be interpreted with caution.
复发性前庭神经鞘瘤（VS）患者在先前手术、立体定向放射外科（SR）或分割放疗（FR）后再次手术，面神经功能恶化的风险增加，例如由于粘连导致面神经功能恶化，这就需要术中监测。面神经“Atrain”肌电图活动（“traintime”）与术后面瘫的程度相关。关于先前接受过手术、SR 或 FR 治疗的 VS 患者的 A-train 研究尚属空白。因此，我们研究了 A-train 监测在接受复发性 VS 二次手术患者中的价值。
回顾性分析 2006 年至 2012 年期间在我院接受复发性 VS 二次手术的患者的术中肌电图数据，这些患者先前曾接受过手术、SR 和/或 FR 治疗。选择了 10 名患者（5 名男性）：7 名患者先前接受过 SR/RT 和 MS 治疗，3 名患者仅接受过手术治疗。将 traintime 值和分布与已发表的阈值以及同期接受首次 VS 手术的 77 名患者进行比较。
A-train 在硬脑膜打开后早期记录，面神经准备前记录。先前接受过 SR/RT 治疗的患者的平均 traintime 为 46.9 秒（18.51 秒-80.82 秒）。仅接受过 MS 治疗的患者的 traintime 分别为 0.06 秒、0.99 秒和 22.46 秒。与文献相比，6 名患者（4 名接受过 SR/RT，2 名未接受过）的 traintime 高于预期，与 77 名首次手术患者相比，7 名患者（5 名接受过 SR/RT）的 traintime 也高于预期。与 77 名首次手术患者中的 60 名（5 名接受过 SR/RT）相比，7 名先前接受过 SR/RT 治疗的患者的 A-train 分布弥散，各通道无明显百分比，而无一例先前手术的患者出现这种情况（p<0.02）。
特别是 SR/RT，而且先前的手术似乎也会导致面神经发生变化，导致过度兴奋和过高的 traintime 值。基于这些发现，在这个特定的患者群体中，应该谨慎解读 A-train 监测结果。
