一侧膈神经上根选择性神经再支配环杓后肌的实验研究

目的 探讨一侧膈神经上根选择性神经再支配环杓后肌的可行性和有效性.方法 8只健康雄性青年Beagle犬作为实验动物,全麻下切断Beagle犬左侧膈神经上根与左侧喉返神经,两断端通过游离神经桥接的方式吻合,并将同侧喉返神经内收肌支切断并植入同侧环杓后肌中;右侧不做任何处理,作为正常对照侧.于手术前、神经修复术后即刻、术后6个月分别行电子喉镜和喉肌电图检查,在最后一次检查后处死动物,取双侧环杓后肌和喉内段喉返神经行组织学检查并与对侧比较.结果 术前8只犬的双侧声带运动正常,术后即刻左侧声带固定,术后6个月均恢复了吸气性外展运动.术前8只犬双侧环杓后肌均能记录到自发肌电位,并引出诱发电位;术后即刻左侧环杓后肌呈电静息,未记录到诱发电位;术后6个月均能记录到自发肌电位,并引出诱发电位,而且两种电位幅度分别与术前比较差异均无统计学意义(均为P>0.05).环杓后肌Masson染色示两侧肌肉纤维相对截面积、胶原纤维相对截面积、肌肉/胶原纤维截面积比差异均无统计学意义(均为P>0.05).喉内段喉返神经甲苯胺蓝染色后示神经纤维分布较均匀密集,且左右两侧喉返神经有髓神经纤维数量差异无统计学意义(P>0.05).结论 左侧膈神经上根选择性神经再支配环杓后肌能有效避免神经错向再生,恢复声带的生理性外展运动.     

Voice quality following laryngeal reinnervation by ansa hypoglossi transfer

Recurrent laryngeal nerve injury resulting in chronic unilateral vocal fold paralysis has been treated traditionally by implantation of various materials into the paralyzed vocal fold. Although the usage of these techniques, especially Teflon®-glycerin paste injection, has been clinically established, they do not restore full functionality to the larynx (abduction, adduction, and vibratory synchronization of the vocal folds). Restoration of these functions, necessary for improved phonation, has been achieved at least on an experimental basis by reinnervation techniques previously described. This study demonstrates excellent human voice quality following reinnervation of the vocal folds in two cases using ansn hypoglossi-recurrent laryngeal nerve anastomosis. Although the reinnervated vocal fold neither abducted nor adducted, it presented itself in the midline for precise apposition with the nonparalyzed cord. Voice data were analyzed within a single subject experimental design at the following intervals: preoperatively, immediately postoperatively, midterm, and long-term (3 and 6 years). The data was analyzed by subjective and objective means, including acoustics and electroglottography. Patient selection, surgical techniques, results, and implications are reviewed.     

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.     

Spontaneous laryngeal reinnervation after recurrent laryngeal or vagus nerve injury

OBJECTIVES: The status of innervation in patients with laryngeal paralysis is somewhat controversial. Electromyographic activity has been frequently documented in the laryngeal muscles of patients with laryngeal paralysis, and animal experiments report a strong propensity for reinnervation after laryngeal nerve injury. However, a study of intraoperative electromyography performed in patients during reinnervation surgery failed to document activity with stimulation of the recurrent laryngeal nerve (RLN). Noting the long-observed differences in the symptoms of patients with vagus nerve injury and those with RLN injury, I hypothesized that reinnervation is influenced by the site of nerve injury. METHODS: Cats were sacrificed at various intervals after resection of 1 cm of either the RLN or the vagus nerve, without any attempt to repair the nerve. RESULTS: Four months after RLN resection, distal nerve biopsy revealed unmyelinated axons scattered through fibrous tissue. By 6 months, myelinated axons were organized, and electromyographic and histologic examination showed preferential reinnervation of the thyroarytenoid muscle. After vagotomy, the RLN was fibrotic and no axons were present. Both the thyroarytenoid and posterior cricoarytenoid muscles were fibrotic and had no electromyographic activity. CONCLUSIONS: The results confirm the strong propensity for laryngeal reinnervation after RLN injury, but not after vagus nerve injury. Preferential reinnervation of adductor muscles may account for a medial position of the paralyzed vocal fold.     

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.     

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。     

Configuration of the glottis in laryngeal paralysis. I: Clinical study

It is widely accepted in the American literature that the cricothyroid muscle is responsible for the paramedian position of the vocal fold in recurrent laryngeal nerve paralysis. However, support in the literature for this theory is not conclusive, and the cadaveric vocal fold position expected after lesions of the vagus nerve has also been reported in patients with an intact superior laryngeal nerve. This study compares the configuration of the glottis in patients with unilateral paralysis due to known lesions of either the recurrent laryngeal or vagus nerve. Normal subjects were studied as controls. Results indicate that the alteration of glottic configuration in laryngeal paralysis cannot be adequately characterized by standard terms of vocal fold position. The paralyzed vocal fold is shortened, with anterior rotation of the arytenoid. Patients with vagus nerve lesions had a statistically insignificant tendency for a more lateral vocal fold position, but a discrete difference in position between the two groups was not identified. This study also confirms prior observations that paralyzed vocal folds are frequently not denervated. These findings have significant implications for management of laryngeal paralysis.     

Does intralaryngeal motor nerve sprouting occur following unilateral recurrent laryngeal nerve paralysis?

Reinnervation of paralyzed intralaryngeal muscles by axonal sprouting from adjacent intact muscles (the phenomenon of muscular neurotization) has been observed, but the source is uncertain. The potential for laryngeal reinnervation of the posterior cricoarytenoid muscle (PCA) from contralateral PCA motor nerve sprouting in a rabbit model was investigated. Unilateral PCA denervation was produced by vagotomy. The rabbits were examined for signs of PCA recovery for up to 6 months using fiberoptic endoscopy, electromyography (EMG), and histology. No return of vocal cord abduction, EMG activity, or any nerve sprouting across the midline from the intact PCA was found. We conclude that there is no significant spontaneous intralaryngeal muscular neurotization to the paralyzed PCA. The clinical ramifications of our data will be discussed.     

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.     

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.     

Thyroarytenoid muscle maintains normal contractile force in chronic vocal fold immobility.

BACKGROUND: Denervation of skeletal muscle typically results in irreversible denervation atrophy over time. This finding has generated controversy as to the efficacy of reinnervation procedures for chronic vocal fold immobility related to recurrent laryngeal nerve injury. OBJECTIVE: To test the hypothesis that chronic vocal fold immobility after recurrent laryngeal nerve injury does not result in diminished maximal isometric force generation in the thyroarytenoid muscle. STUDY DESIGN: Adult random-bred cats underwent either unilateral laryngeal denervation (n = 6) or sham surgery (n = 6). After 6 months, videolaryngoscopy was performed followed by in vitro measurement of maximal isometric tetanic force produced by the thyroarytenoid muscle. RESULTS: All animals in the denervation group showed right vocal fold paralysis after the initial denervation operation; none of these animals had return of appropriately phased movement with respiration. Four had intermittent disorganized twitching movements. One had these movements plus an occasional weak adduction, and one had no movement. Normal vocal fold mobility was observed in 6 of 6 animals undergoing sham surgery. The maximal isometric tetanic force measured from the thyroarytenoid muscle in the sham group was 438 mN (+/-92 mN standard deviation [SD]). The maximal isometric tetanic force measured from the thyroarytenoid muscle in the chronically immobile group was 405 mN (+/-107 mN SD). Differences were not statistically significant. CONCLUSION: Maximal isometric force in the thyroarytenoid muscle is not diminished in chronic vocal fold immobility after recurrent laryngeal nerve injury. We conclude that the possibility for restoration of contractile force to the chronically immobile thyroarytenoid muscle exists. This finding supports the pursuit of reinnervation procedures in the treatment of chronic vocal fold immobility.     

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     

Physiologic motion after vocal cord reinnervation: A preliminary study

This study attempted to reestablish physiologic vocal cord motion, rather than synkinesis, to a rein-nervated vocal cord. One mongrel dog underwent a division and reanastomosis of the anterior branch of the right recurrent laryngeal nerve and simultaneous separation and reimplantation of a posterior division nerve-muscle pedicle into the posterior cricoarytenoid muscle. After 21 weeks, spontaneous physiologic vocal cord movement and electromyographic (EMG) activity were recorded during respiratory obstruction and laryngeal mechanical stimulation. Acoustic measures and histologic data are also presented from the reinnervated and normal vocalis muscle and from the recurrent laryngeal nerve. This study demonstrated that physiologic vocal cord motion can be achieved after laryngeal reinnervation using this technique.     

Configuration of the glottis in laryngeal paralysis. II: Animal experiments

It is widely believed that in isolated recurrent laryngeal nerve paralysis, the paralyzed vocal fold assumes a median or paramedian position, due to the action of the cricothyroid muscle. A review of the literature reveals that support for this theory is not conclusive and, in particular, experiments indicate that the cricothyroid muscle does not appreciably affect vocal fold position in acute paralysis. The research in this study compares the configuration of the glottis in chronic unilateral recurrent laryngeal nerve paralysis in cats, with and without concomitant denervation of the cricothyroid muscle. Results indicate that vocal fold position is not determined by the cricothyroid muscle. Incomplete denervation of intrinsic laryngeal muscles as well as synkinetic reinnervation appear to be significant factors in determining vocal fold position in chronic laryngeal paralysis.     

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.     

Innervation of the paralyzed laryngeal muscles by phrenic motoneurons. A quantitative study by light and electron microscopy.

In the cat, inspiratory opening of the paralyzed glottis recovered after unilateral or bilateral reinnervation of the posterior cricoarytenoid (PCA) muscles by phrenic axons. The morphometric analysis of the regenerated recurrent laryngeal nerves (RLNs), showed that proliferation was abundant; 4 months after the nerve anastomosis, more than 500 myelinated axonal branches repopulated the RLNs. The mean diameter of motor axons (3.5 to 5.0 microns) was lower than in normal phrenic and RLN (8 to 10 microns), and the mean internode length was about half that of the normal RLN. Histochemical examination of the PCA muscle revealed that muscle fiber composition (44% type I and 56% type II muscle fiber) was fairly similar to that of normal PCA. The contraction time of the reinnervated muscles was as long as 60 msec at the time of movement recovery, but it shortened to 25 to 30 msec when the reinnervation time increased. These anatomical and functional results support the choice of the phrenic nerve for laryngeal reinnervation.     

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.     

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.     

Selective cricothyroid muscle reinnervation by muscle-nerve-muscle neurotization

OBJECTIVE: To determine if selective reinnervation of the cricothyroid muscle could be achieved with muscle-nerve-muscle neurotization. DESIGN: Case series. SETTING: Tertiary referral center. PATIENTS: Three consecutive patients with high vagal lesions that resulted in unilateral laryngeal paralysis. INTERVENTIONS: Patients underwent laryngeal reinnervation with ansa hypoglossi to recurrent laryngeal nerve anastomosis. In addition, patients underwent selective cricothyroid muscle reinnervation by muscle-nerve-muscle neurotization technique. MAIN OUTCOME MEASURES: Objective and subjective improvement in voice quality and electromyographic evidence of selective reinnervation of the cricothyroid muscle. RESULTS: All patients recovered normal or near-normal speaking voice and had normal objective measures of voice quality. They also showed electromyographic evidence of cricothyroid muscle reinnervation. CONCLUSION: The muscle-nerve-muscle neurotization technique was successful in providing selective reinnervation of the cricothyroid muscle in our 3 patients.     

An ultrastructural study of the neuromuscular junctions of the cat intrinsic laryngeal muscles. I. Denervation and reinnervation

Morphological changes of the neuromuscular junctions induced by denervation and reinnervation have been investigated electronmicroscopically using cat intrinsic laryngeal muscles. Two experiments were performed: 1. simple transection of the unilateral recurrent laryngeal nerve at the level of the second tracheal ring; 2. neurorrhaphy immediately after the transection at the same level. 1. All the ipsilateral intrinsic laryngeal muscles except for the cricothyroid muscle were denervated 48 hours after the transection of the recurrent laryngeal nerve. In the denervated neuromuscular junctions some primary synaptic clefts were narrowed and others were flattened, while the secondary synaptic clefts were structurally preserved. 2. Some of the regenerating axons returned to the neuromuscular junctions 3 weeks after neurorrhaphy, and all the muscle fibres were reinnervated after 6 weeks. The structural features of the reinnervated neuromuscular junctions were as follows; 1) synaptic vesicles of the nerve terminals were more densely observed, 2) the original postsynaptic membranes were only partially in contact with the regenerated nerve terminals. These conditions persisted until 22 weeks after neurorrhaphy, when the appearance of remyelination was found in the vicinity of the neuromuscular junctions. Using an evoked electromyogram, the presence of neuromuscular transmission was observed 3 weeks after neurorrhaphy, indicating that the structural maturation of the neuromuscular junction was not necessary for neuromuscular transmission.