Esophageal stethoscope. Another possible cause of vocal cord paralysis

Hoarseness after endotracheal intubation can result from compression of the anterior branch of the recurrent laryngeal nerve as it passes behind the thyroid cartilage to innervate the lateral cricoarytenoid muscle. This usually occurs when the cuff of the endotracheal tube lies in the larynx instead of the trachea. When a nasogastric tube is positioned in the midline, resultant postcricoid inflammation can result in vocal cord immobility. This may result from neuropraxia of the posterior branch of the recurrent laryngeal nerve that innervates the posterior cricoarytenoid and interarytenoid muscles, or inflammatory spasm of the interarytenoid muscles themselves. We present a case of vocal cord paralysis after general anesthesia that may have been caused by an esophageal stethoscope. The mechanism for vocal cord immobility could be similar to that of a midline nasogastric tube with resultant postcricoid inflammation. We describe measures that can be taken to prevent vocal cord paralysis after intubation of the larynx or esophagus.     

Bilateral vocal cord paralysis following endotracheal intubation

Bilateral vocal cord paralysis following endotracheal intubation is an uncommon cause of respiratory obstruction. We report one case, adding to ten previously identified. We dissected eight human cadaver larynges and noted the path of the anterior ramus of the recurrent laryngeal nerve. It appeared to be particularly vulnerable to compression injury as it passed between the arytenoid cartilage and the thyroid lamina. This point was confirmed by histologic sections of intubated larynges.     

Vocal cord function following short term endotracheal intubation

Vocal cord function following short term endotracheal intubation This study was undertaken to determine whether brief periods of vocal cord paralysis might commonly occur as a result of tracheal intubation. The vocal cords of 100 patients were examined prior to and after intubation for operation. Although soft tissue trauma was observed in nearly all patients none had evidence of vocal cord paralysis.     

气管插管后声带运动障碍的原因及其相关因素

目的:分析气管插管全身麻醉术后声带运动障碍的原因及其相关因素。方法:通过电子喉镜、频闪喉镜检查、CT三维重建、杓状软骨拨动复位术治疗等判定135例全身麻醉术后声带运动障碍患者的原因。从患者插管条件与插管操作者技术水平、患者体态状况、年龄、带管时间、手术类别以及麻醉过程管理等方面分析声带运动障碍发生原因的相关因素。结果:135例患者中,128例(94.81%)声带运动障碍原因为杓状软骨脱位,7例(5.19%)为声带麻痹。声带运动障碍与插管困难有关者占76.30%;与麻醉过程起伏有关者达65.19%;在插管顺利的患者中,体态及颈部相对瘦长者占90.62%;不同年龄段所占比率差异无统计学意义;带管时间>12h的患者仅占全部声带运动障碍者的9.63%;心胸手术后出现声带运动障碍的发病率近0.50%,占全部声带运动障碍者的59.26%。结论:杓状软骨脱位及声带麻痹是全身麻醉术后声带运动障碍的主要原因;重视患者插管条件和麻醉过程管理,提高插管技术水平有可能降低声带运动障碍原因的发生。     

Lack of evoked laryngeal electromyography response in patients with a clinical diagnosis of vocal cord paralysis

There has been recent debate about whether patients with vocal cord immobility have a neurologic paralysis or whether synkinesis, the misdirection of axons to competing laryngeal muscles, is responsible for the lack of voluntary vocal cord motion. This issue was studied in 15 patients with vocal cord paralysis who underwent laryngeal reinnervation. Evoked electromyography was performed with a surface electrode endotracheal tube. The recurrent laryngeal nerve (RLN) was identified and stimulated with constant current. Of the 15 patients, only 1 produced a compound muscle action potential upon nerve stimulation. The remaining 14 patients had no evoked response during RLN stimulation. A control group of 8 patients with normal vocal cord mobility was studied, and each had a normal evoked electromyography response after RLN stimulation. These results support the assertion that patients who require treatment for vocal cord paralysis do not have synkinesis produced by RLN reinnervation.     

儿童双侧声带麻痹诊治的现状与进展

双侧声带麻痹(BVCP)是指双侧支配咽喉部肌肉运动的神经传导通路受损引起的双侧声带运动障碍,占儿童先天性喉部异常疾病的第二位。主要症状为上气道梗阻、喘鸣、声音嘶哑等。其病因包括神经性、医源性、特发性及其他病因。临床可行病因评估、声带运动振动评估、影像学检查、喉肌电图及喉超声等检查评估。缓解呼吸道阻塞为治疗的主要目的,恢复喉的生理功能为治疗的最终目标。治疗方法有无创正压通气、气管切开术、环状软骨裂开术、杓状软骨切除术、声带后端切断术、声带外移固定术、选择性喉神经修复术、肉毒杆菌毒素注射喉内肌及其他新兴治疗方法。     

Uncommon injuries of the larynx following intubation. Recurrent paralysis, torsion and luxation of the cricoarytenoid joints

19 laryngeal injuries are reported. 16 were secondary to orotracheal intubation and 3 were sequelae of gastroscopy, laryngoscopy and a nasogastric tube. In 6 patients, the trauma followed prolonged nasotracheal intubation, 10 cases followed a single endotracheal intubation. The main symptom was hoarseness. In 6 cases dislocation of an arytenoid cartilage was diagnosed, in 1 case a vocal cord paresis and in the other cases contusion or distortion of the arytenoid joint. In the cases of subluxation the arytenoid cartilage was dislocated posterolaterally, with the cord in the abducted position. For treatment we recommend closed reduction and injection of Cortison-Crystal-suspension into the joint. The outcome is good after single endotracheal intubation, but bad in prolonged nasotracheal intubation because of ankylosis of the cricoarytenoid joint.     

Acute laryngeal injury with short-term endotracheal anesthesia

Endotracheal intubation provides an excellent way of controlling a patient's airway. Except in long term intubation, where pressure necrosis, secondary infection and cicatrix formation are known causes of complications, an endotracheal tube is usually not considered a significant laryngeal hazard. The following case reports of arytenoid dislocation, laryngeal laceration, pseudomembrane formation and vocal cord paralysis, illustrate the etiology and clinical problems that result from unsuspected laryngeal injury following elective short-term endotracheal intubation for anesthetic purposes. Because most post-extubation symptoms are thought to be caused by edema, the larynx is rarely examined, and the patient's symptoms are either ignored or treated with some combination of cold steam, steroids and antibiotics. Diagnosis and management of these injuries, is frequently compromised or delayed until either the symptoms persist for five to seven days or until airway obstruction, severe pain or aphonia develop.     

气管插管后持续性声嘶的原因及其治疗

目的：探讨气管插管后持续性声嘶的原因及评估杓状软骨复位的治疗效果。方法：对78例病人通过检查及疗效观察,确定声嘶原因,采用杓状软骨复位术及肉芽摘除术治疗。结果：78例中,71例为杓状软骨脱位（91．03％）,5例声带麻痹（6．41％）,2例喉内肉芽形成（2．56％）,杓状软骨脱位的病人全部治愈;声带麻痹治疗无效,喉肉芽形成的病人,1例治愈,另1例发音改善,结论：杓状软骨脱位,声带麻痹及喉内肉芽形成是气管插管后持续性声嘶的主要原因;杓状软骨复位术对杓状软骨脱位所致的声嘶疗效明显。     

Laryngeal mask anesthesia with intraoperative laryngoscopy for identification of the recurrent laryngeal nerve during thyroidectomy

OBJECTIVES/HYPOTHESIS: A critical step in thyroidectomy involves definitive identification of the recurrent laryngeal nerve (RLN). Using the laryngeal mask airway, identification of the RLN can be facilitated by stimulation of the nerve while monitoring vocal cord movement with a fiberoptic laryngoscope. We present this technique as an effective and safe means to identify the RLN during thyroid surgery, with significant advantages over existing techniques in appropriately selected patients. STUDY DESIGN: Retrospective case series. METHODS: We performed thyroidectomy on 8 patients (13 RLN identifications) in which laryngeal mask airway anesthesia with fiberoptic laryngoscopy was used to identify the RLN. Results are reviewed with regard to postoperative vocal cord function, as well as intraoperative and postoperative courses with laryngeal mask airway anesthesia. RESULTS: In all 13 cases in which the RLN was sought, it was definitively identified by witnessing brisk vocal cord movement on a video screen with stimulation of the RLN. No patient had postoperative vocal cord paresis or paralysis. Overall recovery from laryngeal mask airway anesthesia was uneventful and had advantages when compared with general anesthesia with endotracheal intubation. CONCLUSIONS: Laryngeal mask airway anesthesia with intraoperative fiberoptic laryngoscopy to identify the RLN is effective and safe in carefully selected patients. Advantages include decreased postoperative throat discomfort, absence of coughing during emergence from anesthesia, and elimination of the possibility of vocal cord mobility impairment secondary to RLN ischemia from the endotracheal tube balloon. In addition, this technique is applicable in operations besides thyroid surgery, in which definitive identification of the RLN is indicated.     

Vocal fold paralysis after anterior cervical spine surgery: incidence, mechanism, and prevention of injury

OBJECTIVE: Vocal fold paralysis is the most common otolaryngological complication after anterior cervical spine surgery (ACSS). However, the frequency and etiology of this injury are not clearly defined. This study was performed to establish the incidence and mechanism of vocal fold paralysis in ACSS and to determine whether controlling for endotracheal tube/laryngeal wall interactions induced by the cervical retraction system could decrease the rate of paralysis. STUDY DESIGN: Retrospective review and complementary cadaver dissection. METHODS: Data gathered on 900 consecutive patients undergoing ACSS were reviewed for complications and procedural risk factors. After the first 250 cases an intervention consisting of monitoring of endotracheal tube cuff pressure and release of pressure after retractor placement or repositioning was employed. This allowed the endotracheal tube to re-center within the larynx. In addition, anterior approaches to the cervical spine were performed on fresh, intubated cadavers and studied with videofluoroscopy following retractor placement. RESULTS: Thirty cases of vocal fold paralysis consistent with recurrent laryngeal nerve injury were identified with three patients having permanent paralysis. With this technique temporary paralysis rates decreased from 6.4% to 1.69% (P = .0002). The cadaver studies confirmed that the retractor displaced the larynx against the shaft of the endotracheal tube with impingement on the vulnerable intralaryngeal segment of the recurrent laryngeal nerve. CONCLUSION: The study results suggest that the most common cause of vocal fold paralysis after anterior cervical spine surgery is compression of the recurrent laryngeal nerve within the endolarynx. Endotracheal tube cuff pressure monitoring and release after retractor placement may prevent injury to the recurrent laryngeal nerve during anterior cervical spine surgery.     

Vocal cord paralysis and superior laryngeal nerve dysfunction in Reye's syndrome

Bilateral vocal cord paralysis and absent laryngeal sensation are previously unrecognized sequelae for Reye's syndrome, a severe acute encephalopathy in children. Four patients were seen at varying periods ranging from 2 weeks to 5 years after their diagnosis of an episode of severe Reye's syndrome over a 20-year period at the Children's Hospital of Los Angeles (Calif). All of the patients had bilateral true vocal cord paralysis with absent laryngeal sensitivity that was documented at endoscopy. As many as 50% of survivors of severe Reye's syndrome have breathy voices or aphonia. It is suggested that some of these children may have vocal cord dysfunction that is not the result of intubation, and are at risk for aspiration and its dangerous sequelae. A vagal nuclear injury is theorized to explain the sensory motor dysfunction of the larynx in these children.     

Subglottic stenosis: a clinicopathological study

Subglottic stenosis is the most common serious long-term complication of endotracheal intubation in neonates and its pathogenesis is poorly understood. We describe the experience of one unit with 15 cases of subglottic stenosis requiring operative intervention seen over a 3-year period and review the pathology and pathogenesis of the condition. In 1 instance operative intervention was successful in treatment and avoided the need for long-term tracheostomy. A possible aetiological factor in at least 2 of the cases of subglottic stenosis was insertion of the wide shoulder of the endotracheal tube through the vocal cords. It is suggested that subglottic stenosis is due to reparative fibrosis following particularly severe acute intubation injury. Another factor may be delayed healing of the subglottic mucosa possibly exacerbated by full thickness cricoid cartilage necrosis. Although severe subglottic injury may occur at any time that the endotracheal tube is in situ, the most critical period is the first week of intubation.     

Arytenoid dislocation

The reported incidence of arytenoid cartilage dislocation is low. This may be due to the wide range and orientation of motion allowed by the cricoarytenoid articulation and the laxity of its joint capsule. In two previously reported instances of arytenoid dislocation, the authors have suggested that endotracheal intubation is generally not sufficient to cause dislocation of an arytenoid cartilage, but that, in their cases, a predisposing factor had set the occasion for dislocation. In this communication, three cases of arytenoid cartilage dislocation, which each followed a single instance of endotracheal intubation are presented. In all three cases, painful swallowing was the main presenting symptom. Clinical features that differentiate arytenoid cartilage dislocation from vocal cord paresis are summarized. Early reduction of the dislocation, while the patient is under local anesthesia, is recommended, and the techniques are described in detail.     

电子喉镜吞咽功能检查在声带麻痹定位诊断中的应用

目的 探讨电子喉镜吞咽功能检查在声带麻痹定位诊断中的应用价值。方法 以15例单侧声带麻痹患者为例,应用电子喉镜对此组患者进行吞咽功能检查,其中左侧声带麻痹10例,右侧声带麻痹5例,发病期5d～10个月。以迷走神经神经节为界,将病变部位分为迷走神经神经节或以上部位的高位病变、迷走神经神经节以下部位的低位病变,其中高位病变4例,低位病变4例,部位不明7例。结果 高位病变组的4例患者,吞咽糊状食物时全部有食物残留于病变侧梨状窝;低位病变组的4例患者,吞咽糊状食物时3例梨状窝无食物残留,仅1例患者同侧梨状窝有食物残留,但是该例患者在同时进行的食管镜检查中发现食管中段癌;7例损伤部位不明的患者中,2例同侧梨状窝有食物残留,5例梨状窝无食物残留。结论 电子喉镜下对单侧声带麻痹患者进行吞咽功能检查,根据病变侧梨状窝有无食物残留可以初步判定喉返神经损伤的部位是在迷走神经节以上或以下部位。     

Recurrent laryngeal nerve palsy and endotracheal intubation.

Voice changes developing after endotracheal intubation have been found to be due to a recurrent laryngeal nerve palsy in four patients. In none of these patients was there any obvious cause and this posed the question whether endotracheal intubation itself could result in a paralysis of the nerve. Cadaver dissection has suggested a way in which which paralysis could occur and this and other possible aetiologies are discussed.     

术中喉返神经监测系统在甲状腺开放手术中的应用

目的总结使用喉返神经监测系统在甲状腺开放手术全过程中,对喉返神经的监测、保护,以及使用体会与注意事项。方法①21例患者中甲状腺恶性肿瘤5例、良性肿瘤9例,甲状腺功能亢进症7例。②喉返神经监测系统主要由监测仪主机、喉返神经刺激探测针、专用接触声带的肌电图（electromyography,EMG）气管插管、接地传导回路电极针、抗干扰探头等组成。③手术采用三步法,首先显露颈迷走神经干检测仪器,再解剖、保护喉返神经,之后切除甲状腺组织。结果全部21例患者,术侧喉返神经均清晰显示,从甲状腺下级血管至入喉处。术后患者发音清晰,无饮水呛咳。结论甲状腺开放手术中,应用＂喉返神经监测系统＂,可使喉返神经在手术全过程中得到切实保护,避免损伤发生。     

Laryngeal synkinesis: its significance to the laryngologist

Basic research and surgical cases have shown that the injured recurrent laryngeal nerve (RLN) may regenerate axons to the larynx that inappropriately innervate both vocal cord adductors and abductors. Innervation of vocal cord adductor muscles by those axons that depolarize during inspiration is particularly devastating to laryngeal function, since it produces medial vocal cord movement during inspiration. Many patients thought to have clinical bilateral vocal cord paralysis can be found to have synkinesis on at least one side. This will make the glottic airway smaller, particularly during inspiration, than would true paralysis of all the intrinsic laryngeal muscles. Patients with bilateral vocal cord paralysis should undergo laryngeal electromyography. If inspiratory innervation of the adductor muscles is present, simple reinnervation of the posterior cricoarytenoid muscle will fail. The adductor muscles also must be denervated by transection of the adductor division of the regenerated RLN.     

Paralysis of the recurrent laryngeal nerve by an extracapsular thyroid adenoma

We treated a patient with an ectopic thyroid adenoma that caused recurrent laryngeal nerve paralysis and upper aerodigestive tract compression. After excision of the mass and release of the compressed recurrent nerve, the true vocal cord function returned almost to normal. We review the literature, diagnosis, and management of thyroid disease associated with vocal cord paralysis.     

Intraoperative Electrophysiologic Monitoring of the Recurrent Laryngeal Nerve

Intraoperative electrophysiologic monitoring of the recurrent laryngeal nerve was performed with a commercially available device consisting of an endotracheal tube with integrated stainless-steel-wire surface EMG electrodes positioned at the level of the true vocal cords. Forty-two recurrent laryngeal nerves were successfully monitored with this system in 31 patients undergoing thyroidectomy or parathyroidectomy. In all cases, evoked EMG responses were elicited by direct electrical recurrent laryngeal nerve stimulation. Stimulus thresholds for evoked responses ranged from 0.2 to 0.6 mA (mean 0.3 mA) for the 37 nerves with preoperative ipsilateral normal vocal cord mobility. Mechanically evoked potentials with acoustic signals were also detected during the surgical procedures related to recurrent laryngeal nerve manipulation. It may be concluded that surface electrode monitoring of the recurrent laryngeal nerve with this system provides a simplified, noninvasive technique that is as sensitive as monitoring with intramuscular laryngeal electrodes.