Laryngeal reinnervation for unilateral traumatic recurrent laryngeal nerve injuries]

OBJECTIVE: To investigate 5 procedures of laryngeal reinnervation for unilateral vocal cord paralysis induced by traumatic recurrent laryngeal nerve injury. METHODS: 35 cases were selected for our study, all patients had unilateral recurrent laryngeal nerve injury, including 8 for nerve decompression, 6 for end to end anastomosis of recurrent laryngeal nerve, 16 for main branch of ansa cervicalis anastomosis to recurrent laryngeal nerve, 3 for nerve muscular pedicle and 2 for nerve implantation. All cases have been subjected to preoperative and postoperative voice recording, acoustic analysis, videolaryngoscopy, strobscopy and electromyography. RESULTS: It is found the adductory and abductory motion of the vocal cord restored in 5 cases with less than 4 months course who received nerve decompression. Although functional motion of vocal cord was not seen in two patients who received nerve decompression with a course longer than 4 months and one less than 4 months, and in all cases who received ansa cervicalis anastomosis and end to end anastomosis of recurrent laryngeal nerve, these procedures resulted in medialization of vocal cord and the mass and tension of the reinnervated vocal cord may become much the same as the contralateral normal vocal cord, thus resuming symmetric vibration of the vocal cords and physiological phonation. Nerve muscular pedicle technique and nerve implantation enabled adductory muscles to be reinnervated, thus improving severe hoarseness, but they didn't restore normal voice. CONCLUSIONS: (1) Nerve decompression seems to be the best procedure in laryngeal reinnervation; (2) Main branch of ansa cervicalis technique raises satisfactory reinnervation of adductor muscles; (3) Selection of the laryngeal reinnervation protocols should depend on the course, severity and type of nerve injury.     

Effects of arytenoid adduction on laryngeal function following ansa cervicalis nerve transfer for vocal fold paralysis in an in vivo canine model

Laryngeal reinnervation with the ansa cervicalis has been proposed as a treatment for human unilateral vocal fold paralysis (UVFP). This study tested the assumption that results from reinnervation could be improved if combined with medialization surgery. Six canine subjects underwent recurrent laryngeal nerve section and reinnervation with a branch of the ansa cervicalis. After reinnervation, vocal function was assessed before and after arytenoid adduction. Although laryngeal function improved significantly following reinnervation, results were significantly enhanced by the addition of medialization surgery. The implications for the treatment of human unilateral vocal fold paralysis are discussed.     

Experimental study on simultaneous selective reinnervation of the adductors and the abductor muscle for the treatment of the laryngeal paralysis

OBJECTIVE: The aim of this study is to estimate the value of a new surgical procedure in the treatment of the chronic unilateral laryngeal paralysis. METHODS: The recurrent laryngeal nerve of the left side of the dog was totally cut and served as a model of unilateral laryngeal paralysis at the first step of the research. The adductor and abductor branches of the recurrent laryngeal nerve were then, selected and cut. Afterwards, they were micro-sutured respectively with one branch of ansa cervicalis and phrenic nerve immediately (group 1) and 4 months later (group 2). Six months after this reinnervation, the laryngeal physiologic function of the lateral crico-arytenoid muscle (LCA) and the posterior crico-arytenoid muscle (PCA) have been checked by the methods of electromyography (EMG) and direct laryngoscopy. All the data have been analysed by the statistic methods. RESULTS: Among all the data of EMG, only the wave amplitude of action potential of the LCA muscle of the group 2 was diminished (p < 0.05). Under the direct laryngoscopy, the adductor movement of the left vocal cord of the group 2 was also lightly reduced. But the adductor and abductor movements of the left vocal cord were synchronous with the mouvements of the right vocal cord. CONCLUSION: Though the result of nervous reinnervation of a four month's laryngeal paralysis was not so good by comparison with that of an immediate reinnervation, this surgical procedure can however on the clinical point of view, reach a satisfactory level. The duration maximum of the reinnervation operation after laryngeal paralysis, is, at the present, not clear. It is necessary for us to make further studies.     

颈袢亚分支植入术治疗单侧喉麻痹的实验研究

用１１只狗，分成实验组（７只）及对照组（４只），均切断左侧喉返神经和左侧喉上神经外支造成单侧喉麻痹。实验组将颈拌（舌下神经拌）主支的各亚分支植入声带内收肌中，对照组不作此神经修复术。６个月后行喉镜检查、喉肌电图检查、肌收缩力测定、组织化学检查及运动终板细胞化学电镜观察，证实实验组声带内收肌获得有效的再神经支配，声带内收为预计亚分支再神经支配的结果，未见吸气性声带内收现象。对照组声带内收肌无再神经支配征象。     

Recurrent nerve/ansa cervicalis nerve anastomosis: a treatment alternative in unilateral recurrent nerve paralysis.

Sectioning of the right recurrent nerve was done in 5 mongrel dogs under general anaesthesia. The distal stump was anastomosed with the ansa cervicalis nerve branch to the sternothyroid muscle. Three to 5 months later the vocal cord movements during light and very light anaesthesia were videorecorded. Under light anaesthesia contraction and medial bulging of the reinnervated right vocal cord occurred in 4 of the dogs. Under very light anaesthesia there was also some adduction of the right vocal cord in these 4 dogs. The right recurrent nerve was then sectioned proximally to the anastomosis and stimulated electrically. In all 5 dogs we observed that electrical stimulation produced a strong adduction of the right vocal cord. Histochemistry of the right vocal and posterior cricoarytenoid muscles showed that reinnervation had taken place. The study indicates that in cases of unilateral vocal cord paralysis an anastomosis between the ansa cervalalis and the recurrent nerve will result in improved phonatory function of the affected vocal cord.     

Recurrent Nerve/Ansa Cervicalis Nerve Anastomosis: A Treatment Alternative in Unilateral Recurrent Nerve Paralysis

Sectioning of the right recurrent nerve was done in 5 mongrel dogs under general anaesthesia. The distal stump was anastomosed with the ansa cervicalis nerve branch to the sternothyroid muscle. Three to 5 months later the vocal cord movements during light and very light anaesthesia were videorecorded. Under light anaesthesia contraction and medial bulging of the reinnervated right vocal cord occurred in 4 of the dogs. Under very light anaesthesia there was also some adduction of the right vocal cord in these 4 dogs. The right recurrent nerve was then sectioned proximally to the anastomosis and stimulated electrically. In all 5 dogs we observed that electrical stimulation produced a strong adduction of the right vocal cord. Histochemistry of the right vocal and posterior cricoarytenoid muscles showed that reinnervation had taken place. The study indicates that in cases of unilateral vocal cord paralysis an anastomosis between the ansa cervicalis and the recurrent nerve will result in improved phonatory function of the affected vocal cord.     

Update: Laryngeal Reinnervation for Unilateral Vocal Cord Paralysis With the Ansa Cervicalis

Eight patients underwent ansa cervicalis anastomosis to the adductor branch of the recurrent laryngeal nerve for unilateral vocal cord paralysis. They were followed long enough (at least 1 year) to determine if the procedure was successful. All cases have been subjected to preoperative and postoperative voice recording, acoustic analysis, and videolaryngoscopy. Some of them have been subjected to stroboscopy and electromyography (EMG). Data from these cases indicate that satisfactory phonatory quality may be achieved after the procedure. The reinnervated vocal cord neither abducted nor adducted, but it presented itself in midline for precise apposition with the normal cord. Synchronous mucosal waves in both vocal cords could be observed. EMG showed that the procedure produced satisfactory reinnervation of the adductory muscles. Therefore, the authors believe that the procedure could be proposed as an alternative to Teflon injection or thyroplasty in selected cases.     

Combined arytenoid adduction and laryngeal reinnervation in the treatment of vocal fold paralysis

OBJECTIVE/HYPOTHESIS: Glottal closure and symmetrical thyroarytenoid stiffness are two important functional characteristics of normal phonatory posture. In the treatment of unilateral vocal cord paralysis, vocal fold medialization improves closure, facilitating entrainment of both vocal folds for improved phonation, and reinnervation is purported to maintain vocal fold bulk and stiffness. A combination of medialization and reinnervation would be expected to further improve vocal quality over medialization alone. STUDY DESIGN: A retrospective review of preoperative and postoperative voice analysis on all patients who underwent arytenoid adduction alone (adduction group) or combined arytenoid adduction and ansa cervicalis to recurrent laryngeal nerve anastomosis (combined group) between 1989 and 1995 for the treatment of unilateral vocal cord paralysis. Patients without postoperative voice analysis were invited back for its completion. A perceptual analysis was designed and completed. METHODS: Videostroboscopic measures of glottal closure, mucosal wave, and symmetry were rated. Aerodynamic parameters of laryngeal airflow and subglottic pressure were measured. A 2-second segment of sustained vowel was used for perceptual analysis by means of a panel of voice professionals and a rating system. Statistical calculations were performed at a significance level of P = .05. RESULTS: There were 9 patients in the adduction group and 10 patients in the combined group. Closure and mucosal wave improved significantly in both groups. Airflow decreased in both groups, but the decrease reached statistical significance only in the adduction group. Subglottic pressure remained unchanged in both groups. Both groups had significant perceptual improvement of voice quality. In all tested parameters the extent of improvement was similar in both groups. CONCLUSION: The role of laryngeal reinnervation in the treatment of unilateral vocal cord paralysis remains to be established.     

Laryngeal reinnervation

In the past, numerous experiments have been performed to attempt reinnervation of the paralyzed larynx. None have been consistently successful. Two experiments were performed in this study, one to restore abduction of a paralyzed vocal cord and one to restore adduction. To paralyze the vocal cord, the recurrent laryngeal nerve was sectioned in all dogs in both experiments. The first experiment was to restore abduction and was performed as follows. An intralaryngeal dissection was performed to separately identify the abductor and adductor branches of the recurrent laryngeal nerve. The adductor branch was sectioned and ligated. Next the phrenic nerve was identified and sectioned. In the dog, the phrenic nerve will not reach the abductor branch of the recurrent laryngeal nerve, so it was sutured to the main trunk of the recurrent laryngeal nerve. Since the adductor branch was severed, regenerating fibers from the phrenic nerve could only grow into the abductor branch and thus to the posterior cricoarytenoid muscle. This experiment produced excellent return of abduction synchronous with inspiration. The second experiment was to restore adduction and was performed as follows. Intralaryngeal dissection was again done to identify the abductor and adductor branches of the recurrent laryngeal nerve. In addition, the motor branch of the superior laryngeal nerve was identified and transected as it entered the cricothyroid muscle. This branch was then anastomosed to the adductor branch of the recurrent laryngeal nerve. The results of this experiment led to chronic adduction of the vocal cord throughout the respiratory cycle. Suggestions for future research include anastomosis of the ansa cervicalis to the abductor branch of the recurrent laryngeal nerve and anastomosis of the main trunk of the vagus nerve to either the abductor or adductor branches of the recurrent laryngeal nerve.     

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.     

喉内收及外展肌选择性再神经支配的实验研究

选用犬１５只，随机分成三组，进行了选择性再神经支配喉内收肌及外展肌功能重建的观察。两个实验组术侧声带最初恢复内收时间为术后３个月，最初恢复外展时间为术后４个月，术后６个月，所有实验组动物的术侧声带均恢复了良好的内收及外展运动，并得到肌电图、肌收缩力及神经肌肉组织化学检查的证实。实验结果表明，同时重建麻痹的声带内收及外展功能是可行且有效的。     

喉返神经修复术及非喉返神经修复术治疗声带麻痹

目的 探讨喉返神经修复术及非喉返神经修复术这两种不同术式治疗声带麻痹的疗效。方法 ①单侧声带麻痹21例, 其中采用喉返神经修复术(喉返神经减压术、颈袢神经与喉返神经吻合术、颈袢神经肌肉蒂环杓侧肌移植术)15例, 采用非喉返神经修复术(声带自体脂肪注射术、自体软骨Ⅰ型甲状软骨成形术)6例;②双侧声带麻痹16例, 其中采用喉返神经修复术(喉返神经减压术、颈袢神经肌肉蒂环杓后肌移植术)6例, 采用非喉返神经修复术(声带外移术、内镜下杓状软骨切除术)10例。治疗前后以电子喉镜、频闪喉镜、声音评估等评价手术疗效。结果 ①单侧喉返神经麻痹患者中喉返神经修复组15例, 术后术侧声带活动不同程度改善, 发音时声带突明显内收, 声带振动及黏膜波均恢复对称性, 声门闭合良好, 手术前后的最大声时为(5.51±1.05)s和(12.10±1.41)s, 差异有统计学意义(P<0.01);非喉返神经修复术术后声带均不同程度内移, 声嘶症状改善, 但声带均无运动, 手术前后的最大声时为(5.47±0.45)s和(11.83±1.47)s, 差异有统计学意义(P<0.01)。神经修复组和非神经修复组术后最大声时比较, 差异无显著性意义(P>0.05);②双侧喉返神经麻痹患者中喉返神经修复术6例中, 术后呼吸困难缓解及声带外展部分恢复4例;非神经修复术10例术后呼吸困难改善;神经修复组术后拔管率为66.7%, 非神经修复组术后拔管率为100%;Fisher精确概率法比较两组术后拔管率, 差异无统计学意义(P>0.05)。结论 对于单侧声带麻痹, 喉返神经修复术及非喉返神经修复术疗效相当, 前者的远期疗效更佳。对于双侧声带麻痹, 非喉返神经修复术疗效更佳, 但喉返神经修复术不影响患者的发音功能。选择喉返神经修复术或非喉返神经修复术治疗声带麻痹, 需要医师根据自身的专业知识及技能、患者的身体状况及需求, 作出慎重的决定, 以取得可靠的疗效。     

几种神经修复术治疗晚期单侧声带麻痹的比较研究

目的：探讨晚期神经修复术以何方法最佳，麻痹的喉肌最多可延长至何时神经修复仍能成功。方法：选成年犬41只，分成颈袢主支吻合组（A）、植入组（B）、肌蒂组（C）及去神经对照组（D）。建立单侧声带麻痹模型，A－C组分别在声带麻痹即刻、6、8、10、12及18个月作3种相应的神经修复术。术后6个月作喉镜、电生理学、肌张力、组织化学检查及超微结构观察。结果：A组失神经10个月以内，B、C组8个月以内作相应神经修复术的动物左声带能恢复不同程度发声内收功能，失神经超过上述时间亚组的动物声带固定。电生理学三参数及肌收缩力均以A组恢复最佳，而B、C组间无明显差异，失神经时间越长，各参数恢复程度越差，得到组织化学及超微结构检查的证实。结论：晚期神经修复术仍以神经吻合术效果最佳，神经值入及肌蒂值入效果无明显差异；神经吻合术组去神经10个月，肌蒂及神经植入术组去神经8个月以内亚组作相应神经修复术能恢复部分喉功能。     

颈袢主支吻合术治疗单侧声带麻痹的临床观察

采用颈袢主支与喉返神经内收肌支吻合术治疗单侧声带麻痹７例。结果表明，声音恢复满意，术后声学三参数频率微扰、振幅微扰及标化嗓音能量均明显减小，平均值均在正常范围之内；喉镜检查发现术侧声带均有不同程度的内移，其中３例恢复至正中位；喉肌电图显示，发育及喉括约活动时术侧喉内收肌恢复与健侧基本同步的密集型强放电，证明术侧喉内收肌获得颈袢主支有效的神经再支配。提示该术是治疗单侧声带麻痹一种理想方法。     

Reinnervation aspects of laryngeal transplantation

Although restoration of laryngeal function after laryngeal transplantation depends on appropriate reinnervation, non-selective reinnervation procedures result in synkinesis and poor function restoration. This study was performed to test the feasibility of selective reinnervation procedures to restore laryngeal function. Three surgical reinnervation procedures were studied each in a group of ten cats: in group 1 a non-selective procedure in which the recurrent laryngeal nerve (RLN) was cut and reanastomosed; in group 2 selective abductor reinnervation was performed with the phrenic nerve; in group 3 selective abductor reinnervation with the phrenic nerve (PN) was combined with selective adductor reinnervation with the ansa cervicalis. Ten weeks after surgical reinnervation abductor and reflex adductor functions were evaluated with videolaryngoscopy and electromyography. Findings demonstrated that non-selective reinnervation not only gave poor abduction during inspiration but even resulted in paradoxical movement during reflex adduction. Selective abductor reinnervation resulted in good abductor function. Selective adductor reinnervation with the ansa cervicalis brought about muscle tonus in the animals studied but no restoration of reflex adduction. Enhanced activity during respiratory distress gave only slight compromise to the abductor function. In all, selective laryngeal reinnervation with the PN and ansa cervicalis produced good restoration of respiratory laryngeal function. However, deglutition following laryngeal motor and sensory reinnervation with protection of the respiratory tract is probably not sufficient, as in the present group of animals no reflex glottic closure was achieved. More research is required. Received: 2 March 1998 / Accepted: 21 April 1998     

Unilateral vocal fold adductor paralysis after tracheal intubation

Vocal fold immobility is a relatively rare complication that can occur after tracheal intubation. Differential diagnoses include a rare clinical entity called unilateral vocal fold adductor paralysis in which only branches entering the thyroarytenoid and lateral cricoarytenoid muscles of the recurrent laryngeal nerve become paralyzed. Computed tomography and laryngeal electromyography are required to distinguish this condition from others such as cricoarytenoid dislocation/subluxation. Here, we describe two patients who developed vocal fold adductor paralysis after intubation. Patient 1 was a 56-year-old man who underwent living-donor liver transplantation and was extubated on day 7 after surgery. Patient 2 was a 52-year-old man who received life support measures including intubation due to ventricular fibrillation, and was extubated two days later. Both were hoarse soon after extubation. Endoscopic laryngeal examination revealed normal abduction and insufficient adduction of paralyzed vocal folds. Computed tomography ruled out cricoarytenoid dislocation/subluxation and laryngeal electromyography confirmed unilateral vocal fold adductor paralysis. Laryngologists should consider this rare pathogenesis.     

Functional Restoration for Recurrent Laryngeal Paralysis: An Experimental Study

The purpose of this investigation was to exclude abductor disturbance and to maintain phonation during recurrent laryngeal nerve paralysis through a new surgical design. This new method consists of implantation of the ansa hypoglossi and sternothyroid muscle pedicle which has been shown to provide sufficient abductor function in a recent publication, and the selective severance of the abductor branch after neurorrhaphy of the recurrent laryngeal which is shown to be a sufficient adductor function in another study. The recovery of sufficient abductor function during inspiration and dyspnea was 67% and 89% of adductor function with phonation. However, after cutting an adductor nerve branch of the recurrent laryngeal nerve in cases of insufficient abduction, the vocal cord on the operated-on side regained abduction during inspiration. The effect of the ansa hypoglossi and sternothyroid muscle pedicle is also discussed.     

Human laryngeal reinnervation: the Northwestern experience

Recent publications have reported impressive success with laryngeal reinnervation utilizing a nerve-muscle pedicle. This innovative surgical procedure is claimed to be useful for unilateral and bilateral vocal cord paralysis. Although the surgical results reported by Tucker have been good, they have lacked corroboration from other centers. We have performed six laryngeal reinnervation procedures at Northwestern University Medical School. Four patients presented with bilateral vocal cord paralysis and two patients with unilateral paralysis. All six operations were successful in restoring vocal cord function. The technique, problems, and results are discussed. Our experience supports the initial reports of success with this new operation.     

Electromyographic findings in recurrent laryngeal nerve reinnervation

Abductor, adductor, and combined reinnervation procedures have been explored with variable success rates. We describe the experience of a tertiary care center with adductor reinnervation procedures, including preoperative and postoperative videostroboscopy and electromyography (EMG) findings. A retrospective chart review was performed from 1997 to 2001 that included 9 patients. Preoperative and postoperative voice comparison was performed by 3 blinded speech pathologists. Clinical comparisons of videostroboscopy findings for vocal fold bulk, tone, position, presence of gap, and movement are elucidated. The preoperative and postoperative EMG findings are described. In all patients, preoperative EMG revealed a dense, complete denervation of the affected recurrent laryngeal nerve. No movement was noted on videostroboscopy with persistent glottic gap. Reinnervation involved a nerve-muscle pedicle or a direct neurorrhaphy of the ansa cervicalis to the recurrent laryngeal nerve. Voice improvement was noted between 60 days and 3 months after reinnervation. Four postoperative EMG studies were performed. An early postoperative EMG study at 5 months revealed activation of the lateral cricoarytenoid muscle and thyroarytenoid muscle with head-lift. Videostroboscopy showed excellent near-midline static positioning of the vocal fold. Late EMG studies, performed 12 to 16 months after reinnervation, revealed "learning" of these muscles, with new activation on "eee" phonation. We conclude that recurrent laryngeal nerve reinnervation procedures belong in the armamentarium of the laryngologist for the treatment of vocal fold paralysis. The EMG findings reported in this study suggest that ongoing reinnervation allows for activation with phonation in matured neuronal anastomoses. Overall, this procedure results in excellent patient acceptance and near-normal vocal quality.     

膈神经替代喉返神经修复治疗双侧声带麻痹

目的 探讨膈神经喉返神经吻合和内收肌支环杓后肌植入术（膈神经手术）治疗双侧喉返神经损伤声带麻痹的有效性、可行性。方法 第二军医大学长海医院耳鼻咽喉科1999年8月－2001年7月治疗外伤性双侧喉返神经损伤声带麻痹6例。病程1周－18个月，一侧作膈神经手术，而另一侧作颈袢肌蒂环杓后肌植入术。手术前后电子喉镜、频闪喉镜观察声门大小、声珲运动、振动情况，噪音声学参数分析，喉肌电力产检查评价手术效果。结果 术后2－3周检查发现4例声门较术前增大2－3mm，但声带固定不动，2例无明显改善。术后6个月5例膈神经修复侧均恢复了较大幅度的吸气性声带外展功能，外展幅度可达3－5mm，而肌蒂植入侧仅轻微外展或固定不动，幅度均在1mm以内。此5例均顺利拔管，并能承受较大强度的体力活动，1例仍在随访中。术后4个月6例肌电图检查显示膈神经修复侧自发、诱发电位均明显大于肌蒂植入侧，自发电活动与肋间肌基本同步，而较肌蒂植入侧延迟100－200ms。声音估价显示3例声嘶术后较术前好转，2例无变化。术后半年肺功能均恢复正常。结论 膈神经喉返神经吻合内收肌支环杓后肌植入术安全可行，较颈袢肌蒂植入术更能有效地恢复声带吸气性外展运动，值得临床推广应用。