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Abstract：
Introduction This study highlights the relation between compound muscle action potential (CMAP) latency variations and the predictive value of facial nerve (FN) proximal-to-distal (P/D) amplitude ratio measured at the end of vestibular schwannoma resection. Methods Forty-eight patients underwent FN stimulation at the brainstem (proximal) and internal acoustic meatus (distal) using a current intensity of 2 mA. The proximal latency and the P/D amplitude ratio were assessed. House-Brackmann grades I & II indicated good FN function, and grades III to VI were considered fair/poor function. A P/D amplitude ratio > 0.6 was used as a cutoff to indicate a good FN function, while a ratio of ≤ 0.6 indicated a fair/poor FN function. Results The P/D amplitude ratio was measured for all patients, and the calculated sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) were 85.2, 85.7, 88.5, and 81.8%, respectively. The CMAPs from the mentalis muscle were then classified based on their proximal latency into group I (< 6 ms), group II (6-8 ms), and group III (> 8 ms). The SE, SP, PPV, and NPV became 90.5, 90.9, 95, and 83.3%, respectively, in group II. In group I, SE and NPV increased, whereas SP and PPV decreased. While in group III, SP and PPV increased, whereas SE and NPV decreased. Conclusion At a latency between 6 and 8 ms, the P/D amplitude ratio was predictive of outcomes with high SE and SP. When latency was < 6 ms or > 8 ms, the same predictive ability was not observed. Knowing the strengths and limitations is important for understanding the predictive value of the P/D amplitude ratio.
摘要：
简介本研究强调了复合肌肉动作电位（CMAP）潜伏期变化与前庭神经鞘瘤切除术结束时测得的面神经（FN）近端到远端（P/D）振幅比的预测值之间的关系。方法48例患者在脑干（近端）和内耳道（远端）使用2mA的电流强度进行FN刺激。评估近端潜伏期和P/D振幅比。House-BrackmannI和II级表明FN功能良好，和III至VI级被认为是正常/差的功能。P/D振幅比>0.6用作截止值以指示良好的FN函数，而≤0.6的比率表明FN功能一般/较差。结果测量所有患者的P/D振幅比，和计算的灵敏度(SE)，特异性（SP），阳性预测值(PPV)，阴性预测值(NPV)分别为85.2、85.7、88.5和81.8%，分别。然后根据它们的近端潜伏期将来自mentalis肌的CMAP分类为I组（<6ms），II组（6-8ms），和组III（>8ms）。TheSE,SP,PPV,净现值分别为90.5、90.9、95和83.3%，分别,在第二组中。在第一组中,SE和NPV增加，而SP和PPV下降。而在第三组中，SP和PPV增加，而SE和NPV下降。结论在6到8ms之间的潜伏期，P/D振幅比可预测高SE和SP的结局.当延迟<6ms或>8ms时，没有观察到相同的预测能力。了解强度和局限性对于理解P/D振幅比的预测值很重要。
