自发和诱发面肌肌电图在听神经瘤术中对神经功能监测与神经预后评估的作用:120例特征分析

背景由于听神经瘤缓慢地膨胀性生长,听神经的解剖位置发生很大的变化,手术中面神经的损伤不可避免.目的总结120例听神经瘤患者术中面神经功能监测的临床经验,了解面神经监测的方法学、准确性、实用性以及术中监测和面神经预后的关系,实现解剖保留面神经功能.设计自身对照观察.单位解放军总医院神经外科.对象于1996-05/2000-02选择解放军总医院神经外科收治的听神经瘤患者120例为研究对象,小型听神经瘤(直径＜2 cm)3例,中型听神经瘤(直径＞2 cm)9例,大型听神经瘤(直径＞3 cm)的108例,其中包括双侧听神经瘤1例,复发性听神经瘤1例;手术采用枕下乳突后入路119例,经迷路入路1例.方法术中使用美国Viking-Ⅳ型多导术中监测仪监测自发和诱发面肌肌电图.监测面神经功能时,记录电极置于眼囵匝肌、口囵匝肌或上唇方肌上,监测三叉神经运动支时,记录电极置于咀嚼肌上;监测副神经时,电极置于斜方肌上.听觉脑干诱发电位测定记录电极为正极,置于额区中线(脑电图10～20分类系统),记录出的波形呈向上的偏转(正),参考电极A1或A2,接地电极置于额极中线(相当于鼻根部);记录电极均为针电极并用胶布固定.一般刺激强度为80～90 nHL,对侧耳用40 nHL的噪声.通过术中监测解剖保留面神经.术后复查CT(必须有增强扫描)或MRI,了解肿瘤的切除程度;术后患者面神经功能的H-B评分(术后2周,6～9个月复诊时再次评分).主要观察指标手术前后听神经瘤患者面神经功能的H-B评分. 结果纳入患者120例,均进入结果分析.①面神经解剖保留117例;1例听神经瘤因面神经呈羽状位于肿瘤的后方,开始切除肿瘤时没有给予电刺激而未能保留,后行面-舌下神经吻合术.2例面神经不慎拉断后两残端足够长且没有张力,故修整后用7-0可吸收线行面神经端-端吻合,术后6个月H-B分级为Ⅳ～Ⅴ级.②术后2周面神经功能的H-B评分为Ⅰ级10例,Ⅱ级57例,Ⅲ级44例,Ⅳ级4例,Ⅴ级2例,Ⅵ级3例.③术后9个月面神经功能的H-B评分为Ⅰ级94例,Ⅱ级18例,Ⅲ级4例,Ⅳ级1例,Ⅴ级1例,Ⅵ级2例.结论通过术中监测自发肌电图结合单极恒压电刺激诱发肌电图可以精确判断面神经的位置,损伤较机械刺激小,面神经的解剖保留率高,且电刺激量由大到小,距离由远及近,定位准确、及时,并可判断面神经预后.

Spontaneous and evoked facial muscle electromyogram in monitoring nervous function in acoustic neuroma surgery and nervous prognosis: A character analysis in 120 cases

BACKGROUND: The anatomical position of facial nerve is often abnormal because of the acoustical neuroma growth, so sometimes, the facial nerve injury is inevitable in the surgery treatment for acoustic neuroma.OBJECTIVE: To investigate the technology, veracity and practicality as well as the relationship between intraoperative monitorning and prognosis of facial nerve, and the clinical experiment was summed up of facial nerve function monitoring in 120 cases of acoustic neuroma surgery.DESIGN: Self-control observation.SETTING: Department of Neurosurgery, General Hospital of Chinese PLA.PARTICIPANTS: Totally 120 patients with acoustic neuroma who received treatment in the Department of Neurosurgery, General Hospital of Chinese PLA from May 1996 to February 2000 were recruited. Among them, 3 cases suffered from small-type acoustic neuroma (＜ 2 cm in diameter), 9 cases from middle-type acoustic neuroma (＞ 2 cm in diameter) and 108 from large-type acoustic neuroma (＞ 3 cm in diameter), including 1 case of bilateral acoustic neuroma and 1 cases of recrudescent acoustic neuroma; Suboccipital retromastoid approach was used in 119 cases and transretrolabyrinthine approach in 1 case.METHODS: American Viking-Ⅳ type monitor was used to monitor facial nervous function. When facial nervous function was monitored, recording electrode was put on orbicular muscle of eye, orbicular muscle of mouth or quadrate muscle of upper lip. When trigeminal motor branch was monitored, recording electrode was put on masseter muscle; When accessory nerve was monitored, recording electrode was put on trapezius muscle.Measurement of evoked auditory brainstem potential: recording electrode was positive electrode and was put at the midline in the frontal region (electroencephalogram 10-20 classification system). The recorded waveshape presented upward deflection. Reference electrode A1 or A2 and ground electrode were put in the midline of frontal pole (relevant to root of nose); Recording electrodes were all needle electrodes and were fixed with adhesive tape. Common stimulus intensity was 80 to 90 nHL, and 40 nHL noise was used in contralateral ear. Facial nerve was reserved following intraoperative monitoring. CT (enhancement scanning was necessary) or MRI was rechecked after operation to investigate the cutting degree of tumor; Facial nerve function was evaluated by H-B scoring (at 2 weeks, or 6 to 9 months following operation).MAIN OUTCOME MEASURES: Facial nerve function by H-B scoring before and after acoustic neuroma surgery.RESULTS: Totally 120 patients were enrolled, and no one dropped out.① Facial nerve anatomy was reserved in 117 cases; One case was failure to reserve facial nerve anatomy because pinnate facial nerve lay behind of acoustic neuroma, and electrical stimulation was not given at the beginning of neuroma resecting, then he received anastomosis of hypoglossal and facial nerve. Nerve of 2 cases was pulled and broken carelessly, and its two stumps were long enough that end-to-end anastomosis of facial nerve was performed with 7-0 absorbable suture following trimming. H-B score was Ⅳ to Ⅴ in the 6th month after surgery. ②Grade Ⅰ of facial nervous function at postoperative 2 weeks was found in 10 cases, grade Ⅱ in 57 cases,grade Ⅲ in 44 eases, grade Ⅳ in 4 cases, grade Ⅴ in 2 cases and gradeⅥ in 3 cases. ③Grade Ⅰ of facial nervous function at postoperative 9 weeks was found in 94 cases, grade Ⅱ in 18 cases, grade Ⅲ in 4 cases,grade Ⅳ in 1 case and grade Ⅵ in 2 cases.CONCLUSION: Spontaneous and evoked facial muscle electromyogram may be helpful to make sure the facial nervous position exactly and estimate the prognosis of facial nerve.