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.     

神经肌蒂移植术治疗声带麻痹的对比实验研究

目的;比较不同神经肌蒂环榴后肌移植术治疗声带麻痹的疗效,为临床选择术式提供参考。方法：建立联合性喉麻痹模型。分别用颈袢胸骨舌骨肌肌蒂（简称颈袢组）和副神经胸锁乳突肌肌蒂（简称副神经组）移植于环杓后肌,以恢复声外展功能,术后４个月,分别进行录音,直达喉镜和电视喉动态镜观察声带运动并录像,喉肌电图检查,环榴后肌透射电子显射镜检查和酶组织化学检查,并进行电脑图像定量分析。结果：术后颈袢组和副神经组犬吠声     

Human laryngeal reinnervation

Bilateral vocal cord paralysis is fortunately an uncommon occurrence although the incidence of this injury secondary to external neck trauma is increasing. In general, a patient with this lesion is faced with the choice between adequate airway at the expense of a breathy, weak voice or a fairly good voice with the need for a permanent tracheotomy. In an effort to provide a better solution to this dilemma, an attempt has been made to develop a means of reinnervation of at least one vocal cord without the problems inherent in the usual nerve anastomosis techniques. After extensive preliminary work in dogs the nerve-muscle pedicle technique for reinnervation has been developed. In this procedure the branch of the ansa hypoglossi to the anterior belly of the omohyoid is mobilized and a small block of muscle containing the terminal branches is freed from the muscle proper. Using an approach similar to the Woodman arytenoidectomy, the posterior cricoarytenoid muscle is exposed, and its fibers are partially incised. The previously prepared nerve-muscle pedicle is sutured to it. In the first five patients subjected to this procedure, return of spontaneous abduction of the reinnervated vocal cord was noted between six and eight weeks post surgery. In no case was the voice weakened nor was there any problem with aspiration. All five patients have achieved sufficient air-way so that exercise tolerance for daily activities is adequate without a tracheotomy. The physiologic and histologic background of this technique is discussed in detail.     

Studies of early laryngeal reinnervation

In 1973, Hengerer and Tucker reported a method for laryngeal reinnervation. The purpose of this study is to objectively verify the reinnervation mechanism in 20 dogs with nerve-muscle pedicle grafts. Three months after the experimental operation direct stimulation of the nerve to the neuromuscular pedicle produced an evoked action potential of the posterior cricoarytenoid muscle. This was recorded. Histologic examination of the posterior cricoarytenoid muscle and the nerve-muscle pedicle were performed. The electromyogram revealed in ten of fifteen dogs an excitable action potential. This can be considered as objective evidence for reinnervation from the neuromuscular pedicle.     

不同延期神经再支配环杓后肌方法的疗效观察

目的：探讨环杓后肌延期神经再支配的方法及时机。方法：将２９只狗分成三组，两个实验组在喉返神经切断后即刻、４、６、８、１０、１２个月分别将膈神经与喉返神经吻合选择性支配环杓后肌和颈袢神经—胸骨甲状肌蒂植入环杓后肌，对照组喉返神经切断后各时间不作任何手术。结果：两个实验组６个月后行喉镜、神经肌电及肌收缩力、组织化学证实：神经吻合组各时间效果明显好于神经肌蒂植入组，但两种术式疗效均随病程延长而下降。结论：神经吻合法延期神经再支配环杓后肌６个月内效果较好，而神经肌蒂植入法治疗环杓后肌麻痹最好不晚于失神经后４个月，否则效果不佳     

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.     

Study on contractile properties of the posterior cricoarytenoid muscle after delayed reinnervation]

To study date on the contractile properties of posterior cricoarytenoid muscle after delayed reinnervation of different reinnervated methods. Twenty four dogs were reinnervated at 0,4,5,6,10 and 12 month interval following recurrent laryngeal nerve via the phrenic nerve anastomosed to the recurrent laryngeal nerve after cutting the adductor branch and ansa cervicalis-sternothyroid muscle pedicle implanted into the posterior cricoarytenoid muscle. After 6 months, a series of contractions were recorded from each side in twenty living dogs. The results showed that contractile force of reinnervated muscle decreased gradually with the time of denervation, but contractile force of muscle was no significantly difference between reinnervated side of nerve anastomosed group in 4 months after denervated and normal side, and it was significantly difference between nerve anastomosed group and nerve-muscle pedicle implanted group at some time of delayed reinnervation. The contractile time of reinnervated side of two operated groups was similar to that of normal side. The conclusion demonstrated that the contractile properties can indicate exactly reinnervated degree of muscle, and the earlier reinnervation was performed, the better curative effect was.     

神经肌蒂移植同时恢复麻痹声带内收及外展功能的实验研究

目的 探索一种能同时恢复麻痹声带内收及外展功能的治疗方法。方法 对狗一侧喉返神经及喉上神经运动支联合麻痹的喉内肌,采用颈袢胸骨甲状肌肌蒂移植于麻痹环杓后肌,颈袢甲状舌骨肌肌蒂移植于麻痹侧环杓侧肌作为实验组,并仅用颈袢胸骨甲状肌肌蒂移植于麻痹侧环杓后肌作为对照组。术前及术后４个月行声带录像、喉肌电图检测、组织学检查。结果术后４个月所有动物均不同程度地恢复了麻痹声带的生物功能。实验组术侧声带内运动明显     

Vocal cord abduction rehabilitation by nervous selective anastomosis

Laryngeal reinnervation procedures were performed on 15 dogs. An anastomosis was performed between a selected motor branch of the ansa hypoglossi and the posterior cricoarytenoid nerve. The results were analyzed endoscopically, electromyographically, and histologically. Results were satisfactory in 12 cases. The methods and results have been compared with those obtained using other reinnervation techniques.     

Newer technique of laryngeal reinnervation: superior laryngeal nerve (motor branch) as a driver of the posterior cricoarytenoid muscle

This report analyzes the experience gained using two different techniques to reinnervate the paralyzed vocal cord. In the neurotization group, the superior laryngeal nerve (SLN) motor branch-cricothyroid muscle pedicle was used to reinnervate the posterior cricoarytenoid muscle. In the direct nerve anastomosis group, the SLN was anastomosed to the abductor branch of the recurrent laryngeal nerve (RLN), and the ansa hypoglossi (AH) to the adductor branch of the RLN. A third group of animals (control) had the right RLN sectioned without any anastomosis. About 5 to 6 months postoperatively the animals were killed painlessly and evaluated. The neurotization group revealed vocal fold mobilization on the right side to have an average of about half of the mobility of the left, normal side. After the RLN and SLN on the left were severed as well as the AH bilaterally, the vocal cord mobility was reduced to about one fourth. The direct nerve anastomosis group showed about fourfold less vocal cord mobility than the neurotization group. After the SLN, RLN, and AH were severed bilaterally, the control group showed no vocal cord mobility. The neurotization technique has been selected for further experimentation in human adults.     

Experimental reinnervation of a strap muscle with a few roots of the phrenic nerve in rabbits.

In order to compare application of the roots of the phrenic nerve to the ansa hypoglossi for laryngeal muscle neurotization, 1 or more roots from the phrenic nerve were implanted into the right sternothyroid (RST) muscle of rabbits (n = 36). Controls were intact animals (in which RST innervation is provided by the ansa; n = 6) and denervated ones (n = 6). At 66 +/- 2 days (mean +/- SE) after neurotization, during quiet breathing, inspiratory electromyographic activity and isometric contraction force were observed in all reinnervated RST muscles (n = 24). During maximal inspiratory effort, electromyographic activity and force increased. In animals reinnervated by the C4 root alone, forces (46.22 +/- 7.8 g) were significantly higher than in intact animals (10.83 +/- 5.0 g). Retrograde labeling proved the phrenic origin of the neurotization. Electromyography of the diaphragm was recorded. We conclude that in rabbits, neurotization of a strap muscle by 1 or 2 roots of the phrenic nerve allows inspiratory contraction, even during quiet breathing. Such inspiratory activity is not observed in sternothyroid muscles of intact animals innervated by the ansa hypoglossi.     

环杓后肌延期神经再支配后收缩特性的定量分析

为观察延期神经再支配环杓后肌的收缩特性，比较不同神经再支配方法的疗效，我们选择２４只犬，在右喉返神经切断后，于即刻，４，６，８，１０和１２个月时，分别以２只犬行选择性膈神经与喉返神经吻合（切断内收肌支）支配右环杓后肌（神经吻合组）；另１２只犬分别以２只行颈袢胸骨甲状肌蒂植入右环杓后肌（神经植入组）。组后饲养６个月，测定环杓后肌收缩强度及时间。结果表明，两组术侧的环杓后肌收缩力恢复率随病程延长而下降     

A histochemical evaluation of experimentally reinnervated canine laryngeal muscles

Sixteen dogs underwent different types of experimental reinnervation procedures of the posterior cricoarytenoid (PCA) muscle - reinnervation by the recurrent nerve itself (self-reinnervation) (n = 6), by the ansa cervicalis nerve (n = 5) or by the phrenic nerve (n = 5). After functional evaluation the normal left and the reinnervated right PCA muscles were removed for histochemical analysis. Cryostat sections were incubated for actomyosin ATPase, NADH-TR and alpha-GPDH. All muscles showed microscopical evidence of successful reinnervation. There was a slight change in the muscle fiber type composition in the reinnervated muscle as compared to the normal side. Incubations for the NADH-TR and alpha-GPDH showed less staining intensity in the reinnervated muscles. The histochemical differences between normal and reinnervated muscles were small, however, and probably of minor importance with regard to the function of the muscles.     

Animal experiment studies of collateral reinnervation of denervated laryngeal musculature

The course of atrophy of type I and type II muscle fibers of the posterior cricoarytenoid muscle, the lateral cricoarytenoid muscle and the medial thyroarytenoid muscle of 9 dogs have been investigated after resection of the ipsilateral recurrent laryngeal nerve after 2, 4 and 10 months. Using ATP-ase staining the histochemical results revealed a predominant atrophy of type II fibers, a reactive hypertrophy of type I fibers after a period of 4 months and a pattern of type-grouping with signs of a complete reinnervation in all laryngeal muscles within 10 months. The existence of a supplementary innervation of the intrinsic laryngeal muscles in dogs and its implication on experiments in laryngeal reinnervation are discussed.     

Contractile properties of canine thyroarytenoid muscle reinnervated from the ansa cervicalis

In an attempt to obtain data on the contractile properties of vocal fold muscle reinnervated from the ansa cervicalis, we severed the recurrent nerve and connected its distal stump to the ansa cervicalis by an end-to-end anastomosis in a series of dogs. Each dog was allowed to heal for 5 months. Then the section of the thyroid cartilage on which the vocal fold muscle inserted was detached, connected to an isometric force transducer, and activated by indirect stimulation successively on both the operated and unoperated sides. A series of twitch contractions was recorded from each side. In two dogs no contractile response was obtained. In the three others, the twitch contraction time was increased significantly, by 23% to 60%. In two of three dogs, the operated muscle was significantly weaker than the unoperated muscle. The reinnervated thyroarytenoid muscle changed its speed in the direction of the donor sternothyroid muscle.     

The role of the posterior cricoarytenoid muscle in phonation: an electromyographic investigation in dogs

The activity of the posterior cricoarytenoid muscle during respiration has been well investigated electromyographically. Its activity during phonation, however, has not been studied systematically. We, therefore, focused our attention on the phonatory activity of the posterior cricoarytenoid muscle to confirm whether it also contracts during phonation, as has been reported by some researchers. In our series of 12 adult dogs, the posterior cricoarytenoid was active in 11 dogs and inactive in one dog during phonation. Our present study also showed that the posterior cricoarytenoid activity was stronger for phonation than for inspiration in 6, stronger for inspiration than for phonation in 3, and the same for phonation and inspiration in 2 dogs. The results obtained from the present electromyographic evaluation demonstrated that the posterior cricoarytenoid is activated during phonation. The authors believe that the posterior cricoarytenoid muscle has phonatory function and that the phonatory effect of this muscle on the vocal cord may play an important role in precise glottis control.     

The deep temporal nerve-orbicularis oculi muscle pedicle as a possible means for reanimation of the upper face

Selective reinnervation of paralyzed facial musculature using the ansa hypoglossi nerve-muscle pedicle has been shown to be feasible in laboratory animals and in people. Because this structure cannot be brought beyond the level of the orbicularis oris muscle, the deep temporal nerve-orbicularis oculi nerve-muscle pedicle was investigated in six human cadavers as a possible source for reanimation of the paralyzed upper face. These studies show that it is possible to create a nerve-muscle pedicle that can easily reach the orbicularis oculi muscle in all specimens. Interest in electrical control of paralyzed structures to reestablish facial expression may allow further application of our findings.     

Intrinsic laryngeal muscle reinnervation using the muscle-nerve-muscle technique

OBJECTIVES: This study was performed to investigate the muscle-nerve-muscle reinnervation technique in the larynx, in which a nerve conduit implanted into an innervated muscle conducts axonal sprouting into a denervated muscle while maintaining function of the donor muscle. METHODS: In this study, the muscle-nerve-muscle technique was used to direct superior laryngeal nerve axons to reinnervate intrinsic laryngeal muscles by implanting the recurrent laryngeal nerve stump into the cricothyroid muscle in 8 dogs. In 4 of the dogs, the recurrent laryngeal nerve trunk to the adductor muscles was divided so that all axonal sprouting was directed to the posterior cricoarytenoid muscle. Six-month electromyography data were obtained from 6 of the 8 dogs. RESULTS: All 6 dogs showed evidence of successful reinnervation of the thyroarytenoid or posterior cricoarytenoid muscles with action potentials that corresponded to spontaneous respiratory efforts, while the donor cricothyroid muscles retained their phasic contraction. These responses were obliterated when the recurrent laryngeal nerve conduit was divided. Histologic examination of the intrinsic laryngeal muscles demonstrated successful reinnervation. CONCLUSIONS: The results confirm that intrinsic laryngeal muscles may be successfully reinnervated by the superior laryngeal nerve with the muscle-nerve-muscle technique, without sacrifice of function of the cricothyroid muscle. This method offers an alternative source of appropriately firing axons for laryngeal reinnervation procedures.     

家犬双侧环杓后肌失神经及颈袢神经再支配后肌卫星细胞活性变化

目的 探讨家犬双侧环杓后肌失神经支配及用颈袢神经再吻合支配后肌卫星细胞活性的变化.方法 随机数字表法将24只家犬分成3组,每组8只,分别为切断双侧喉返神经组,切断喉返神经后即刻颈袢神经再吻合组,不切断喉返神经的对照组.3组动物手术后再饲养9周后再次暴露喉返神经及环杓后肌,使用喉返神经诱发环杓后肌电位来验证喉返神经的再通情况;双盲法提取环杓后肌肌肉组织中总RNA,反转录后做实时定量聚合酶链反应(PCR)检测肌卫星细胞增殖分化标记物Myogenin、Myf5和Pax7的mRNA表达.结果 手术后3组动物各有1只死亡或感染退出实验.术后9周诱发神经环杓后肌肌电图提示对照组动物喉返神经功能均正常,切断组7只动物电刺激都没有反应,吻合组均有神经再通.Myogenin的mRNA相对表达量切断组较对照组和吻合组均有明显升高(Z值为1.42和1.38,P值均＜0.05),Myf5的mRNA表达切断组也明显高于对照组和吻合组(Z值为1.66和1.69,P值均＜0.01);切断组Pax7的mRNA表达明显高于对照组(Z=1.66,P＜0.01),也高于吻合组(Z=1.42,P＜0.05);而吻合组与对照组Myogenin、Myf5和Pax7的mRNA表达差异均无统计学意义(P值均＞0.05).结论 双侧喉返神经切断后,环杓后肌的肌卫星细胞增殖分化的mRNA表达增强,而同颈袢神经再吻合后肌卫星细胞的增殖分化表达下降.

Abstract：

Objective To investigate the activity of bilateral posterior cricoarytenoid muscle satellite cell after denervation or reinnervation with ansa cervicalis. Methods Twenty four dogs were randomly divided into 3 groups. The bilateral laryngeal recurrent nerves were cut in group one in all dogs. The bilateral laryngeal recurrent nerves were anastomosed with ansa cervicalis after incision in group two in all dogs. The dogs in group three were used as control. Nine weeks after surgery, the electromyography was used to test the regeneration of the nerve. The posterior cricoarytenoid muscles biopsy were collected. The expression of mRNA of Myogenin, Myf5, and Pax7 was assayed by realtime RT-PCR after total RNA isolation. Results Two dogs died after surgery in incision and anastomose group. The electromyography suggested that the RLN of all dogs had denervated in the incision group and had reinnervated in the anastomose group after 9 weeks. Myogenin mRNA from RLN incision dogs PCA muscles had greater expression versus controls ( Z = 1.42, P ＜ 0. 01 ) or anastomosed dogs ( Z = 1.38, P ＜ 0. 01 ). Myf5 mRNA expression from RLN incision dogs PCA muscles had significant increase versus control dogs ( Z = 1.66, P ＜0. 01 ) or anastomosed dogs ( Z = 1.69, P ＜ 0. 01 ). Pax7 mRNA expression from RNL incision dogs had significant increase compared with control ( Z = 1.66, P ＜0. 01 ) or anastomosed animals ( Z = 1.42, P ＜0. 05 ). There was no significant difference in Myogenin ( Z = 1.34, P ＞ 0. 05 ), Myf5 ( Z = 0. 54, P ＞0. 05) and Pax ( Z = 0. 54, P ＞ 0. 05 ) mRNA expression between controls and anastomosed animals.Conclusions The bilateral denervation of RLN cause significantly increasing in dog PCA muscle satellite cell proliferation and differentiation. The bilateral reinnervation of RLN cause PCA muscle satellite cell come back nonproliferative, quiescent state in dog.