耳科手术中面神经监测仪的应用

目的探讨面神经监测仪在耳科手术中的应用价值.方法在22例耳科手术时,用面神经监测仪监测面神经,并比较手术时面神经水平段的暴露情况与面神经电流刺激阈值的关系.结果6例面神经骨管完整患者的电流刺激阈值为0.41～0.97mA;12例面神经骨管缺损但表面有黏膜及软组织覆盖者的电流刺激阈值为0.08～0.26mA;4例面神经直接暴露者的电流刺激阈值为0.06～0.16mA.经统计学分析,3组差异有显著性(P＜0.05).结论耳科手术时应用面神经监测仪可判断面神经骨管状况及探测面神经走行,是耳科手术时防止面神经损伤的有效辅助设备.     

术中面神经肌电监护在腮腺手术中的应用

目的：探讨术中面神经肌电监护在腮腺良性肿瘤中的应用及效果。方法：在20例腮腺良性肿瘤手术中,均采用面神经主干解剖法,应用面神经肌电监护进行术中面神经定位及解剖分离,并对其结果进行分析。结果：20例腮腺良性肿瘤手术平均时间为1．5h,术后面神经功能保全良好,术后随访0．5～3年,无一例复发及涎漏。结论：在腮腺手术中采用面神经监护可以缩短手术时间,减少面神经损伤,值得临床应用。     

Facial nerve monitoring in middle ear and mastoid surgery

HYPOTHESIS: Intraoperative electromyographic facial nerve monitoring, long accepted as the standard of care in surgery for acoustic neuroma and other cerebellopontine angle tumors, may be of aid in middle ear and mastoid surgery. STUDY DESIGN: Retrospective series of 262 cases of middle ear/mastoid surgery in which monitoring was performed by a neurophysiologist. METHODS: Neurophysiological monitoring events were classified as mechanical or electrical. The voltages producing facial nerve stimulation were compiled and compared with observed facial nerve dehiscence. RESULTS: The most common use of monitoring was localization of the facial nerve by electrical stimulation (60%) or identification of mechanically evoked activity (39%). In 57 cases (36%), the first electrical stimulation event evoked a facial nerve response at less than 1 V threshold, indicating little or no bony covering. The minimum stimulation threshold throughout each of these cases was less than 1 V in 88 of the 159 cases (55%) in which stimulation was attempted. In contrast, the facial nerve was visibly dehiscent in only 35 cases (13%). Neurophysiological monitoring confirmed aberrant facial nerve course through the temporal bone in four cases resulting in cancellation of surgical treatment in two cases. Postoperative facial nerve function was preserved in all cases when present preoperatively. CONCLUSIONS: An electrical stimulation threshold of less than 1 V is a more useful criterion of dehiscence than observation under the operating microscope. The absence of monitoring events allows safe dissection. Monitoring can help locate the facial nerve, guide the dissection and drilling, and confirm its integrity, thereby allowing more definitive surgical treatment while preserving neural function.     

Facial nerve mapping and monitoring in lymphatic malformation surgery

Objective

Establish the efficacy of preoperative facial nerve mapping and continuous intraoperative EMG monitoring in protecting the facial nerve during resection of cervicofacial lymphatic malformations.

Methods

Retrospective study in which patients were clinically followed for at least 6 months postoperatively, and long-term outcome was evaluated. Patient demographics, lesion characteristics (i.e., size, stage, location) were recorded. Operative notes revealed surgical techniques, findings, and complications. Preoperative, short-/long-term postoperative facial nerve function was standardized using the House-Brackmann Classification. Mapping was done prior to incision by percutaneously stimulating the facial nerve and its branches and recording the motor responses. Intraoperative monitoring and mapping were accomplished using a four-channel, free-running EMG. Neurophysiologists continuously monitored EMG responses and blindly analyzed intraoperative findings and final EMG interpretations for abnormalities.

Results

Seven patients collectively underwent 8 lymphatic malformation surgeries. Median age was 30 months (2-105 months). Lymphatic malformation diagnosis was recorded in 6/8 surgeries. Facial nerve function was House-Brackmann grade I in 8/8 cases preoperatively. Facial nerve was abnormally elongated in 1/8 cases. EMG monitoring recorded abnormal activity in 4/8 cases—two suggesting facial nerve irritation, and two with possible facial nerve damage. Transient or long-term facial nerve paresis occurred in 1/8 cases (House-Brackmann grade II).

Conclusions

Preoperative facial nerve mapping combined with continuous intraoperative EMG and mapping is a successful method of identifying the facial nerve course and protecting it from injury during resection of cervicofacial lymphatic malformations involving the facial nerve.     

Facial nerve lying lateral to ossicles in one case of congenital aural atresia

An abnormal facial nerve (FN) course can be found in a significant number of patients with congenital aural atresia. However, the literature does not include any cases in which the tympanic portion of the FN was displaced lateral to ossicles. We report a unique case of unilateral congenital aural atresia with this rare FN displacement. A review of the existing literature and a discussion are also provided.     

Fully implantable hearing aids in patients with congenital auricular atresia

INTRODUCTION: Patients with congenital auricular atresia suffer from a conductive hearing loss (HL) with an air-bone gap of 50 to 60 dB. Conventional bone conducting or bone anchored hearing aids are treatment options with several disadvantages and a biophysical limitation of almost no sound attenuation in the skull bone. Surgical construction of the sound conducting apparatus has been performed by others and modified by us into a three-step procedure with in vivo prefabrication of the external ear canal and the tympanic membrane. Although the results improved after inauguration of our modifications, there still remains an air-bone gap that makes air conducting hearing aids necessary in many patients. Implantable hearing aids have been developed for patients with perceptional HL and normal middle ear function but not for patients with middle ear disease or malformation. OBJECTIVES: Our objectives were to improve the hearing results of auricular atresia. STUDY DESIGN: Prospective. METHODS: The surgical instruments, the transducer, and the operative technique of the only fully implantable hearing aid (Otologics Fully Implantable Middle Ear Transducer) clinically available were modified. They were implanted in five patients with congenital auricular atresia and their audiologic outcome evaluated. RESULTS: After activation and fitting of the devices, patients experienced an improvement of sound-field thresholds up to 50 dB HL. The mean functional gain in a three frequency pure-tone average was approximately 35 dB HL. CONCLUSIONS: This technique appears to provide a completely new dimension for the audiologic rehabilitation of patients with severe malformation of the middle ear.     

Combined reconstruction of congenital auricular atresia and severe microtia

OBJECTIVES: Due to their embryologic developments, auricular atresia and severe microtia are in most cases combined malformations. The aims of this study were to develop a surgical technique for combined esthetic and functional reconstruction with a minimum of operations and to evaluate the results. STUDY DESIGN: Prospective clinical evaluation. PATIENTS AND METHODS: Fifty-two patients with third-degree microtia and congenital aural atresia with a sound-conducting block of about 50 dB were treated as described here. In the first operation, autogenous cartilage is harvested and the auricular framework fabricated and implanted. In addition, the tympanic membrane and the external ear canal are prefabricated and stored in a subcutaneous pocket. In the second step, the elevation of the new framework is combined with the operation for atresia utilizing the prefabricated tympanic membrane and external ear canal. In the third step, the cavum conchae is deepened and the external ear canal opened and covered with a skin graft. RESULTS: Seventy-six percent of the patients had a final conducting hearing loss of 30 dB or less. No restenosis of the new external ear canal was observed. The esthetic results of the constructed auricles are shown. CONCLUSION: With this combination of plastic surgery for the auricle and functional surgery for the middle ear, no additional operations are necessary, and the prefabrication of the external ear canal and the tympanic membrane gives stable and reliable results. Therefore, we think that this combined technique offers the best chance for an optimal esthetic and functional rehabilitation of patients with these malformations.     

Multicenter clinical study of bone-anchored hearing aids in Japan--application for congenital auricular atresia

The effectiveness of bone anchored hearing aid (BAHA) for the patients with congenital aural atresia was evaluated by multicenter clinical study in Japan. Twenty patients (17 bilateral and 3 hemilateral) of congenital auricular atresia were registered for this study and finally, 18 of them (15 bilateral and 3 unilateral) were subjected to further evaluation. Primary endpoint of this study was free sound-field pure-tone audiometory and speech threshold hearing test in quiet and noisy circumstances. Secondary endpoint of this study was patient's satisfaction based upon APHAB (Abbreviated Profile of Hearing Aid Benefit) questionnaire survey. These results were compared between before and 12 weeks after BAHA surgery. Both hearing level of pure tone and speech threshold significantly improved after BAHA surgery. APHAB scores also suggested the improvement of the QOL after BAHA usage, except for the scores that concerned with unpleasantness of noisy sound. BAHA is one of the useful options for the treatment of congenital auricular atresia.     

Facial nerve monitoring in otologic surgery: clinical indications and intraoperative technique

While identification of the intratemporal portion of the facial nerve is mandatory in most otologic surgical procedures, inadvertent instrumentation, traction, or thermal injury may still result from inaccurate delineation, purposeful avoidance, or false protection of this critical structure. Improved functional preservation of the facial nerve has been achieved in acoustic neuroma surgery through the monitoring of evoked facial electromyographic activity. This technique may also be used during otologic procedures in which facial nerve manipulation is anticipated in the management of recurrent cholesteatoma, temporal bone trauma, congenital deformity, or purposeful access for cochlear implantation. Potential indications for using facial nerve monitoring in contemporary otologic surgery are detailed through illustrative case presentations, and necessary instrumentation and techniques are briefly reviewed. Intraoperative monitoring can assist the surgeon in isolating the facial nerve when chronic inflammation, traumatic injury, or anomalous development has resulted in distortion or absence of microanatomic landmarks.     

影像导航在骨性外耳道闭锁手术的应用

目的 观察影像导航(image-guided surgery,IGS)下行外耳道骨性闭锁手术的应用效果.方法 分析2001～2004年患C型(Schuknecht分类)先天性小耳畸形病例36耳.试验组(IGS组)18耳,年龄12～29岁,术后随访6个月～1年;对照组(非IGS组)18耳,年龄10～27岁,术后随访6个月～3年.两组均采用鼓窦径路听力重建,由同一手术组完成;比较两组手术时间、术者感觉和听力学改变.结果 所有患者外耳道完全骨性闭锁,骨链畸形,鼓室发育不全,面神经畸形.术前颞骨CT未充分显示畸形的水平半规管,术中导航得以证实.IGS组手术准备时间增加20分钟(15～30分钟),实际手术时间(2小时32分钟)减少25分钟,总时间IGS组则减少5分钟.IGS配准率在0.6 mm～1.3 mm之间,平均0.84 mm.确保术野所见与IGS影像完美结合,使术者感觉更安全.IGS组1例,非IGS组3例术后出现部分外耳道再狭窄.两组均未出现面瘫和术后全聋,均获得明显的听力改善(平均听阈:IGS=31.8 dB,非IGS=30.5 dB).结论 IGS可用于C型外耳道骨性闭锁手术,对术者是一种有益的辅助手段,尤其当解剖标志变异,手术入路受限时,有助于明确手术方向,减少并发症;但IGS仅能明确术腔情况,其技术本身对提高听力无明显作用.     

中耳手术中面神经监测的应用

目的 评价术中面神经监测在中耳手术中的作用并系统化其监测方法,探讨全身麻醉对神经监测的影响.方法 40例鼓室成形术中应用面神经实时监测,静脉输注罗库溴铵维持50%的肌松程度.根据术中直视下面神经暴露程度,分为面神经暴露组(A组,n=16)和面神经非暴露组(B组,n=24),测定面神经诱发肌电位的电刺激阈值.结果 所有病例均成功诱发面神经肌电位反应,且术后面神经功能均未见异常.50%肌松程度下面神经暴露组电刺激阈值为0.15 mA±0.07mA(0.07～0.25 mA),面神经非暴露组电刺激阈值为0.53 mA±0.21mA(0.20～1.00mA).两者比较,差异有统计学意义(P<0.001).结论 中耳手术中面神经监测有助于定位面神经,预警手术操作,避免医源性面神经损伤.定位未暴露的面神经时,可先用0.5mA刺激,再用1.0mA探寻;面神经暴露时,用0.1mA开始刺激.部分神经肌肉阻滞技术可以满足面神经监测的需要.     

Facial nerve rerouting in skull base surgery

Facial nerve rerouting techniques were developed to facilitate re-section of extensive tumors occupying the skull base. Facial nerve rerouting has its own limitations and risks, requiring microsurgical expertise, additional surgical time, and often some degree of facial nerve paresis. This article presents different degrees of anterior and posterior facial nerve rerouting, techniques of facial nerve rerouting, and a comprehensive review of outcomes. It then reviews anatomic and functional preservation of the facial nerve in acoustic neuroma resection, technical aspects of facial nerve dissection, intracranial facial nerve repair options, and outcomes for successful acoustic neuroma surgery.     

Facial nerve management in cranial base surgery

This study reviewed 124 patients who required facial nerve manipulation during cranial base surgery. Most of them underwent only nerve displacement or selective transection for improved surgical access to the cranial base (70 and 34, respectively). Fourteen patients had the facial nerve resected for oncologic reasons and repaired with primary nerve grafting. Most patients regained quite satisfactory facial function with quality correlating with the degree of nerve injury. Six patients had facial nerve resected as part of oncologic palliation and had the facial deficit rehabilitated with regional tissue. A correlation between preoperative facial nerve weakness and the quality of nerve graft function was not found. An oncologic correlation, however, is suggested (patients with preoperative weakness had less favorable prognosis). Overall, patients who require facial nerve resection for oncologic reasons do not do as well as those with normal preoperative function.     

Facial nerve schwannoma in revision stapedotomy surgery

We describe a male patient who presented a progressive conductive unilateral hearing loss 20 years after otosclerosis surgery. Computed tomography (CT) scan and magnetic resonance imaging (MRI) findings suggested a facial schwannoma in its tympanic segment. At the time of revision surgery, a facial schwannoma was found to originate at the tympanic segment, pushing the prosthesis out of the oval window fenestration. The Teflon-piston was repositioned with difficulties in the central platinotomy, and the facial schwannoma was left intact.     

Facial nerve anomalies in association with congenital hearing loss

OBJECTIVE: Facial nerve (FN) anomalies are exceedingly rare. The association between a hearing loss and an anomalous facial nerve has never been touched deeply in the literature. The aim of this study is to report facial nerve anomalies in patients presenting with congenital hearing loss (COHL) and/or facial nerve palsy. METHODS: A retrospective chart review over 10 years from two academic tertiary referral centers. Eight patients were diagnosed with facial nerve anomalies in association with congenital hearing loss. The age ranged from 7 months to 13 years. RESULTS: Five patients had conductive congenital hearing loss (CCHL). Two had congenital sensorineural hearing loss (CSNHL). The eighth patient had a mixed hearing loss (MHL). Surgical findings for patients with conductive congenital hearing loss included facial nerve passing inferior to oval window (OW) (two patients), facial nerve covering head of stapes (three patients), deformed stapes (two patient), deformed incus (two patient), and absent incus (one patient). Radiological findings for patients with congenital sensorineural hearing loss and mixed hearing loss include, single cavity anomaly (one patient), dilated vestibule and superior semicircular canal (one patient), and absent internal auditory canal (IAC) (two patients). For patients with conductive congenital hearing loss, the radiological findings consistency demonstrates a soft tissue opacification in the middle ear. CONCLUSIONS: Congenital hearing loss may be associated with facial nerve anomalies. Pediatric otolaryngologists should be cautious when exploring patients with conductive congenital hearing loss.     

Facial nerve monitoring during acoustic neuroma removal

As the surgeon's ability to perform total acoustic tumor removal without major neurologic deficit has reached a pinnacle, preservation of facial nerve function has assumed a higher priority. Satisfactory postoperative facial function depends upon an anatomically and physiologically intact facial nerve. Precise localization of the facial nerve is the first step toward preservation of function. Intraoperative facial nerve (FN) stimulation allows the surgeon to safely locate the facial nerve. Monitoring evoked electromyographic activity with an audio speaker provides direct, ongoing information regarding trauma to the nerve during dissection. Intraoperative FN monitoring was used in 18 consecutive translabyrinthine acoustic tumor removals. Seventeen patients had an excellent facial nerve result (Grade I or II using the House 6-point scale). The authors conclude that intraoperative FN stimulation and monitoring during acoustic tumor removal is a safe and reliable method of locating and protecting the facial nerve during cerebellopontine angle surgery.