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.     

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.     

Experimental Study on Reinnervation of Vocal Cord Adductors With the Ansa Cervicalis

The purpose of this study was to reestablish the adduction of the paralyzed vocal cord through reinnervation of the adductor muscles for unilateral vocal cord paralysis. In nine dogs, the adductor branch of the recurrent laryngeal nerve was anastomosed to the main branch of the ansa cervicalis. Six months later, various techniques of observation showed that seven of nine cases had excellent to good adduction during whining. Adduction was caused by reinnervation of the adductor muscles from the ansa cervicalis as demonstrated by laryngeal spontaneous and evoked electromyography, contraction tension, and various histologic findings. Therefore, the new technique could be a good treatment of unilateral vocal cord paralysis.     

Hypoglossal nerve transfer for laryngeal reinnervation: a preliminary study

The hypoglossal nerve is a logical donor nerve for hemilaryngeal reinnervation because 1) its activity coincides with normal laryngeal adduction during speech and deglutition; 2) it is a large nerve with many axons; and 3) donor site morbidity is low. This method of laryngeal reinnervation has not been previously reported. Previous studies using the ansa cervicalis for reinnervation have failed to show spontaneous activity. Hypoglossal-to-recurrent laryngeal nerve anastomosis was performed on a series of 5 dogs. The vocal folds were viewed monthly, with the animals awake, by infraglottic examination through a permanent tracheostomy. One dog failed due to technical error. The remaining 4 dogs began to exhibit spontaneous vocal fold adduction within 2 to 4 months. Vocal fold motion was synchronous with spontaneous tongue motion. Complete glottic closure was seen during swallowing at 3 to 5 months. Intraglottic pressure measurements following reinnervation were normal. Hypoglossal nerve transfer appears to be capable of providing functional adduction to the paralyzed hemilarynx. The potential advantages and disadvantages of this new technique are discussed.     

Experimental laryngeal reinnervation by phrenic nerve implantation into the posterior cricoarytenoid muscle

Under general anaesthesia, 5 dogs underwent sectioning of the right recurrent nerve followed by implantation of the phrenic nerve into the posterior cricoarytenoid (PCA) muscle. Some 6-7 months later the dogs were sacrificed after registration of vocal cord motility. Still photographs and movie film of the larynx were taken during quiet and forced respiration and at electrical stimulation of the implanted phrenic nerve. The PCA and vocal muscles were removed for histochemical studies. We found practically no abductory movement of the vocal cord on the reinnervated side, either during quiet or forced respiration. During forced inspiration there was, however, a slight medial bowing of the right vocal cord. At electrical stimulation there was a sphincteric movement of the entire larynx. Histochemistry showed a reinnervation picture of both the PCA and the vocal muscles on the experimental side. The conclusion drawn from this study is that axonal escape, probably from the implantation site, results in an unwanted reinnervation of laryngeal adductor muscles, which neutralize the abducting effect of the PCA muscle during inspiration. This method therefore does not seem to be suitable as a treatment alternative for bilateral recurrent nerve paralysis.     

Experimental laryngeal reinnervation by phrenic nerve implantation into the posterior cricoarytenoid muscle

Under general anaesthesia, 5 dogs underwent sectioning of the right recurrent nerve followed by implantation of the phrenic nerve into the posterior cricoarytenoid (PCA) muscle. Some 6-7 months later the dogs were sacrificed after registration of vocal cord motility. Still photographs and movie film of the larynx were taken during quiet and forced respiration and at electrical stimulation of the implanted phrenic nerve. The PCA and vocal muscles were removed for histochemical studies. We found practically no abductory movement of the vocal cord on the reinnervated side, either during quiet or forced respiration. During forced inspiration there was, however, a slight medial bowing of the right vocal cord. At electrical stimulation there was a sphincteric movement of the entire larynx. Histochemistry showed a reinnervation picture of both the PCA and the vocal muscles on the experimental side. The conclusion drawn from this study is that axonal escape, probably from the implantation site, results in an unwanted reinnervation of laryngeal adductor muscles, which neutralize the abducting effect of the PCA muscle during inspiration. This method therefore does not seem to be suitable as a treatment alternative for bilateral recurrent nerve paralysis.     

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.     

Electromyographic study on end-to-end anastomosis of the recurrent laryngeal nerve in dogs

The effectiveness of anastomosis of a divided recurrent laryngeal nerve was studied with electromyography as well as visual observation. Results obtained through this investigation permitted the following conclusions: 1. Regenerated potentials were recorded from both the involved thyroarytenoid and posterior cricoarytenoid muscles for an average of 5 to 6 weeks postoperatively. 2. Average onset of recovery of spontaneous adduction was 10 weeks following surgery, and four dogs regained complete recovery of adduction in 13 to 14 weeks. Average onset of recovery of spontaneous abduction was 11.8 weeks postoperatively, and none of the four dogs displayed complete recovery. 3. The time delay between the onset of regenerated potentials and onset of recovery of cord mobility averaged 4.2 weeks for adduction and 6.4 weeks for abduction. 4. Incomplete recovery of movements of the reinnervated vocal cord might be due to an inadequate number of effective motor units. 5. End-to-end anastomosis of the recurrent laryngeal nerve can be performed as one method of reinnervating the denervated intrinsic laryngeal muscles, and further histological studies should be carried out to determine if the regenerated nerve fibers actually have decreased.     

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.     

神经端侧吻合术治疗声带麻痹的实验研究

目的 :研究神经端侧吻合术治疗声带麻痹的效果及临床应用价值。方法 :6 0只SD大鼠被分为 3组 ,实验组为神经端侧吻合组 ,切断右侧喉返神经 ,将其远断端与右侧膈神经行神经端侧吻合 ,然后切断喉返神经内收支 ,将颈袢的胸骨舌骨肌支与内收支行神经端端吻合 ;对照组为神经端端吻合组 ,切断右侧喉返神经后将其远断端与右侧切断的膈神经近断端行神经端端吻合 ,其他同实验组 ;以上两组均将右侧的喉上神经切断 ,并结扎断端 ,排除环甲肌对声带活动的影响。正常组仅暴露上述神经后不作任何处理。术后 1、3个月利用纤维喉镜及神经肌电图观察声带活动及神经再生情况。结果 :术后 1个月实验组与对照组手术效果差异有显著性意义 (P<0 .0 5 ) ;术后 3个月差异无显著性意义 (P >0 .0 5 )。结论 :神经端侧吻合术手术效果与神经端端吻合术相似 ,并且避免了膈神经的损伤 ,保护了膈肌功能 ,为喉返神经修复术提供了一种新的手术方法。     

Functional remobilization evaluation of the paralyzed vocal cord by end-to-side neurorrhaphy in rats

OBJECTIVE: To investigate the value of end-to-side neurorrhaphy to treat vocal cord paralysis. STUDY DESIGN: A prospective study evaluating the effects of end-to-side neurorrhaphy to treat vocal cord paralysis by means of fiberoptic laryngoscopy and nerve electromyography. METHODS: Thirty Sprague-Dawley rats were divided into experimental group 1, experimental group 2, and a control group randomly. Right recurrent laryngeal nerve (RLN) was incised, and the distal end of the RLN was anastomosed to the right phrenic nerve by end-to-side neurorrhaphy in experimental group 1 or by end-to-end nerve anastomosis in experimental group 2, respectively. The adductor nerve branch of the right RLN was incised and anastomosed to the proximal end of the right ansa cervicalis nerve by end-to-end nerve anastomosis. Fiberoptic laryngoscopy and nerve electromyography were used to examine the vocal cord movement and nerve regeneration. RESULTS: Three months after operation, this effect of end-to-side neurorrhaphy created a significant difference compared with the end-to-end nerve anastomosis (P < .05). The end-to-side neurorrhaphy did not lead to vocal cord movement compared with end-to-end nerve anastomosis. CONCLUSION: Vocal cord paralysis cannot be treated by this microsurgical technique.     

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。     

Restoration of physiologic vocal fold abduction with the ansa cervicalis nerve

An attempt was made to restore physiologic abduction of the vocal fold using the ansa cervicalis nerve. In adult dogs, the ansa cervicalis nerve was anastomosed to the abductor branch of the recurrent laryngeal nerve. In the four surviving dogs, abduction of approximately 50% to 70% of normal was restored synchronous with inspiration. This technique seems to work almost as well as the phrenic nerve and is easier to perform.     

几丁质管桥接喉返神经缺损的实验研究

为在恢复神经再支配手术治疗喉返神经损伤所致的喉麻痹中,探索一种新的可避免神经误向支配的方法,采用非神经生物材料几了质管,桥接狗喉返神经干的缺损,并用自体神经移植作为对照组.术后5个月,组织学、组织化学和电生理等检测,显示两组动物的喉内肌皆获得神经再支配.实验组术侧声带较明显恢复了和健侧一致的内收和外展运动,甲杓肌(Thyroarytenoid,TAM)和环杓后肌(Posterior cricoarytenoid musdes,PCAM)也分别出现了相应的生理性自发肌电;对照组的术侧声带无明显的运动,TAM和PCAM则在呼气期和吸气期均出现不规则的持续密集自发肌电.提示几丁质桥接喉返神经干缺损可使其定向性再生,选择性支配喉内肌.     

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.     

Neurorrhaphy of the recurrent laryngeal nerve.

The authors have experimentally performed neurorrhaphy and its modifications and nerve grafting with end-to-end anastomosis of the recurrent laryngeal nerve in dogs. Recovery of a neurorrhaphy of the recurrent laryngeal nerve resulted in the bizarre and spasmodic movement of the vocal cords. These effects were recorded by means of electromyography and 16 mm cinematography to demonstrate restoration of nerve muscle function and vocal cord movements. From these results, it was concluded that these single modes were not adequate for restoration of laryngeal function, however, some specific attention is given to a few trophic changes of the affected muscles after a period of ten months postoperative.     

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.     

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.     

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     

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。