Bilateral Selective Laryngeal Reinnervation for Bilateral Vocal Fold Paralysis in Children.

Importance: Bilateral vocal fold paralysis (BVFP) in pediatric patients is a challenging entity with multiple causes. Traditional approaches to managing BVFP include tracheostomy, arytenoidectomy, suture lateralization, cordotomy, and posterior cricoid enlargement. These interventions are used to create a stable airway but risk compromising voice quality. Objectives: To assess the use of bilateral selective laryngeal reinnervation (SLR) surgery to manage BVFP and restore dynamic function to the larynx in pediatric patients. Design, Setting, and Participants: In this case series performed at 2 tertiary care academic institutions, 8 pediatric patients underwent bilateral SLR to treat BVFP (5 patients with iatrogenic BVFP and 3 with congenital BVFP) from November 2004 to August 2018 with follow-up for at least 1.5 years. Interventions: Bilateral selective laryngeal reinnervation surgery. Main Outcomes and Measures: Flexible laryngoscopy findings, subjective and objective measures of voice quality, subjective swallowing function, and decannulation in patients who were previously dependent on a tracheostomy tube. Results: Participants included 6 boys and 2 girls with a median age of 9.3 (range, 2.2 to 18.0) years at the time of surgery. All 8 patients were decannulated; 6 patients had preoperative tracheostomies and 2 had perioperative tracheostomies. Voice quality, as measured using the GRBAS (grade, roughness, breathiness, asthenia, strain) scale, improved in 6 of 8 patients after reinnervation, and swallowing was not impaired in any patients. In 2 patients, GRBAS scale scores remained the same before and after surgery. Inspiratory vocal fold abduction was observed on both sides in 5 patients and on 1 side in 2 patients, with no active abduction observed in 1 patient. The follow-up period was more than 5 years in 7 of 8 patients and at least 1.5 years in all patients. Conclusions and Relevance: Bilateral SLR appears to be a promising treatment option for children with BVFP; it is currently the only option, to our knowledge, with the potential to restore abductor and adductor vocal fold movement. In patients with complete paralysis, this procedure may provide a strategy for airway management and restoration of the dynamic function of the larynx. It could be considered as a first-line technique before endolaryngeal or airway framework procedures, which carry a risk of compromising voice quality.

Relative direction and position of recurrent laryngeal nerve for anatomical configuration.

The present study aims to describe the course of the recurrent laryngeal nerve (RLN) using the tracheoesophageal groove (TEG) at the cricothyroid joint as a base line, and the configuration of RLN and inferior thyroid artery (ITA) for careful dissection in thyroid surgery. The RLN of left side is likely to be found posterior to ITA and course mainly from 0 degrees up to 30 degrees based on TEG near cricothyroid joint while the nerve of right side is likely to be found anterior to ITA in right side and course mainly from 15 degrees up to 45 degrees based on TEG. The contacting point of RLN with ITA locate from the tip of cricoid cartilage at about three tenth of the distance from the tip of cricoid cartilage to sternal notch without reference to individual body size. 70 cadavers were investigated. The angle of RLN from TEG was measured at the cricothyroid joint. The relative position of RLN to ITA was classified. The location of the contacting point of RLN with ITA was measured and converted as an index. These findings suggest the area for careful dissection near cricothyroid joint, the configuration of RLN for identifying the nerve.

Useful landmarks in arytenoid adduction and laryngeal reinnervation surgery.

OBJECTIVE: Knowledge of the location of the muscular process of the arytenoid cartilage and the recurrent laryngeal nerve is essential to performing a successful arytenoid adduction and laryngeal reinnervation surgery. We describe external landmarks useful in locating these structures. STUDY DESIGN: Cadaveric laryngeal dissection. METHODS: Posterior laryngeal dissection was performed in 16 human larynges. The position of the muscular process of the arytenoid was measured bilaterally relative to the inferior and superior borders of the thyroid lamina. The recurrent laryngeal nerve was followed distally from slightly below the level of the cricothyroid joint to its genu where its vertical course changes to an oblique intralaryngeal course. RESULTS: The muscular process of the arytenoid was usually found halfway between the roots of the superior and inferior cornu of the thyroid lamina. The recurrent laryngeal nerve was found just deep to the cricothyroid joint and lateral to the posterior cricoarytenoid muscle. There were no other nerves in this area. CONCLUSIONS: This study finds that the superior and inferior borders of the thyroid lamina are useful intraoperative landmarks to locate the muscular process of the arytenoid. The cricothyroid joint provides a good starting point to locate the recurrent laryngeal nerve, which can be identified slightly deeper between it and the posterior cricoarytenoid muscle.

Partial cricotracheal resection for successful reversal of laryngotracheal separation in patients with chronic aspiration.

OBJECTIVE: To present our experience with successful reversal of laryngotracheal separation in patients with chronic aspiration, to discuss our surgical technique, and to review the literature. STUDY DESIGN: Retrospective case review. METHODS: The medical records of two patients who underwent a successful reversal of laryngotracheal reversal after separation were reviewed. The two patients were evaluated clinically with videostroboscopy and videofluoroscopy. RESULTS: Both patients presented with intractable aspiration despite protective tracheostomy because of impairment of lower cranial nerve function. After laryngotracheal separation, swallowing rehabilitation was safely possible, and neurologic improvement allowed reversal of the separation procedure. For reversal, we present the use of a partial cricotracheal resection with tracheocricothyropexia similar to the technique used for subglottic stenosis. Both patients were successfully reversed. Satisfactory voice and swallowing function 7 and 10 years after reversal, respectively, could be assessed through our evaluation. Review of the literature revealed a total of 13 cases of successful reversal after laryngotracheal separation. Technical details of surgery and functional results are rarely reported.

Intrinsic laryngeal muscle reinnervation with nerve-muscle pedicle.

OBJECTIVE: To test the application of the nerve-muscle pedicle (NMP) technique for selective reinnervation of previously denervated posterior cricoarytenoid (PCA) muscle. METHODS: The left recurrent laryngeal nerve (RLN) was severed in 5 mongrel dogs, and an ansa cervicalis-sternohyoid muscle pedicle was sutured to the left PCA muscle. Three dogs underwent a sham operation. Videolaryngoscopy was performed, and electromyographic data were collected after 1 year on average. Finally, histologic analysis of the NMP was performed. RESULTS: The video records showed the return of mobility of the PCA muscle reinnervated by the NMP. EMG data as to show evoked polyphasic potentials showed also evidence of reinnervation of the PCA muscle. With immunohistochemical reaction (antineurofilament antibody+biotin) we could show neurofilaments and motor endplates in both sides in all 5 animals. CONCLUSIONS: The NMP technique could eliminate the need for arytenoidectomy and laterofixation in patients with unilateral or bilateral vocal fold paralysis. The quality of life and voice may be improved.

Nerve branches to the posterior cricoarytenoid muscle may complicate the laryngeal reinnervation procedure.

OBJECTIVES/HYPOTHESIS: To better understand the reason for the low success rate of posterior cricoarytenoid (PCA) muscle reinnervation, we attempted to identify the communicating branches that may exist between the nerve branch to the PCA muscle and the other laryngeal adductors in addition to the interarytenoid (IA) muscle. STUDY DESIGN: Quantitative histological assessment. METHODS: Twenty human hemilarynges from patients with laryngeal or hypopharyngeal cancer were obtained after surgery and stained with Sihler's stain, which rendered the muscle translucent while counterstaining the neuroanatomy of the recurrent laryngeal nerve (RLN) inside the larynges. RESULTS: The nerve supply to the PCA muscle was separated into two main branches. One upper branch supplied the horizontal compartment, and the lower branch supplied the vertical/oblique compartment. In 14 specimens, two nerve branches to the PCA muscle arose separately from the RLN. In six specimens, one single main branch arose from the RLN and immediately ramified into two secondary branches. In all specimens except one, the nerve branch to the horizontal compartment was connected to the IA muscle. However, no communicating branches were observed between the nerve to the PCA muscle and the other laryngeal adductors. No anastomosis between nerve branches to the horizontal and vertical/oblique compartments or other variations of nerve distribution were observed. CONCLUSIONS: The communicating branches between the nerve branches to the PCA muscle and the IA muscle may be the only branch, complicating the reinnervation procedure. More investigations are needed to identify variations in the terminal branch distribution from the RLN. LEVEL OF EVIDENCE: NA.

Understanding the motor innervation of the human cricopharyngeus muscle.

A comprehensive understanding of the swallow mechanism continues to suffer from an incomplete appreciation of basic morphology and function. This article is intended to underscore our currently incomplete and pending understanding of cricopharyngeus motor innervation in humans. Given the critical function of this sphincteric muscle in the control of the proximal alimentary tract, a focused effort to unravel its motor innervation would go a long way to reduce the mystery of its overall role in normal and disordered function in patients.

The innervation of the human posterior cricoarytenoid muscle: evidence for at least two neuromuscular compartments.

Recent work has demonstrated that the dog posterior cricoarytenoid (PCA) muscle is composed of three neuromuscular compartments: a vertical, an oblique, and a horizontal. In this study, the human PCA muscle was examined for evidence of neural compartments. Fifteen human PCA muscles were processed by Sihler's stain, which renders the muscle translucent while counterstaining the nerve supply. The results clearly show that in all specimens the nerve supply of the human PCA muscle is separated into at least two main branches: one supplies the horizontal compartment and a second further subdivides to innervate both the vertical and oblique compartments. In 10 of the specimens, these nerve branches arose as separate branches from the recurrent laryngeal nerve. In all specimens, the nerve branch to the horizontal compartment was either combined or connected with the nerve branch to the interarytenoid muscle. The results suggest that the different compartments of the PCA muscle have distinct functions. In addition, the strong connections with the interarytenoid nerve complicate reinnervation procedures to reanimate a paralyzed or transplanted larynx.

Age-related changes in the neuromuscular junctions in the human posterior cricoarytenoid muscles: a quantitative study.

The posterior cricoarytenoid muscle is unique histochemically, ultrastructurally, and functionally. It has been suggested that the posterior cricoarytenoid muscle undergoes early aging. Aging in peripheral nerves has been reported to resemble a "dying back" neuropathy in that the most severe and earliest age-related changes occur at the most distal levels of the nerve fibers. The lengths and terminal axonal branching of neuromuscular junctions in 17 human posterior cricoarytenoid muscles aged 4 days to 95 years were determined. Both neuromuscular junction lengths and the numbers of axonal terminal branches in the very young group differed significantly from values in two older groups. In contrast to results reported for some other muscles, there was no significant age-related change in these parameters in the posterior cricoarytenoid muscle during adult life. This difference may be related to the repetitive contraction of the posterior cricoarytenoid muscle.

The human communicating nerve. An extension of the external superior laryngeal nerve that innervates the vocal cord.

OBJECTIVE: A second source of motor innervation for the thyroarytenoid (TA) muscle, other than the recurrent laryngeal nerve, has been suggested by clinical and experimental observations. Early anatomists noted what appeared to be small nerves connecting the cricothyroid and TA muscles; however, these observations were disputed by later anatomists and subsequently forgotten. METHOD: In this study, we processed 27 human hemilarynges with Sihler's stain, a technique that clears soft tissue and counterstains nerve. In addition, four communicating nerves (CNs) were frozen sectioned and stained for acetylcholinesterase, a marker for motor neurons. RESULTS: In 12 (44%) of the 27 specimens, a neural connection was found that exited the medial surface of the cricothyroid muscle and then entered into the lateral surface of the TA muscle. In general, this CN was composed of two parts: an intramuscular branch usually combined with the recurrent laryngeal nerve or terminated within the TA muscle directly and an extramuscular branch that passed through the TA muscle and terminated in the subglottic mucosa and around the cricoarytenoid joint. All four CNs tested positive for acetylcholinesterase. Specifically, the CNs contained an average of 2510 myelinated axons, of which 785 (31%) were motor neurons. CONCLUSION: The results suggest that when the CN is present, it supplies a second source of motor innervation to the TA muscle and extensive sensory innervation to the subglottic area and cricoarytenoid joint. In addition, the CN may be the nerve of the fifth branchial arch, a structure that has never been identified (to our knowledge).

Intracellular recording from posterior cricoarytenoid motoneurons in the rat.

The ability to maintain coordinated vocal cord abduction and upper airway patency is dependent on the integrity of the posterior cricoarytenoid (PCA) motoneurons and their multiple neural connections. Study of the PCA motoneurons represents the initial step in understanding the complex mechanisms responsible for coordinated vocal cord abduction and may provide an insight into the possible pathological processes underlying the various clinical presentations of vocal cord dysfunction. Intracellular recordings were made from 11 PCA motoneurons in Sprague-Dawley rats, which all showed an inspiratory augmenting discharge pattern that is also characteristic of phrenic nerve activity. The resting membrane potential was -56+/-11 mV. Two PCA motoneurons were injected with Neurobiotin to demonstrate neuronal morphology, which was found to be similar to that obtained by retrograde labeling with cholera toxin B subunit. The technique described for intracellular recording of PCA motoneurons should allow more detailed morphological, electrophysiological, and immunohistochemical information to be obtained, to thereby identify some of the factors responsible for maintaining normal function of the PCA muscle.

Motor innervation of the human cricopharyngeus muscle.

Innervation of the human cricopharyngeus muscle remains historically controversial and unclear, encouraging numerous treatments inconsistently designed to pharmacologically or mechanically alter the contractile state of this muscle. Neuroanatomic controversy results from and is perpetuated by 1) use of nonhuman models, 2) observational misinterpretation of small-diameter, overlapping nerve fibers, and, most importantly, 3) lack of real-time verification of neural projections. We sought to overcome these difficulties by performing microdissections in 27 patients undergoing laryngectomy and using real-time electromyographic verification. We demonstrated 1) dual ipsilateral innervation by the pharyngeal plexus and recurrent laryngeal nerve, 2) segmental projection of the recurrent laryngeal nerve to anterior motor units, 3) pharyngeal plexus projection to posterior motor units, 4) absence of a sympathetic or external superior laryngeal nerve contribution, and 5) absence of contralateral innervation. Such dual ipsilateral innervation, segmentally projected, has not been previously described in any other form of neuromuscular organization. Neuroanatomic accuracy should improve diagnostic and therapeutic strategies for future management of pharyngeal dysphagia.

The superior laryngeal nerve: function and dysfunction.

Despite long-standing clinical interest in SLN dysfunction, most aspects of this entity continue to require clarification. The replacement of the laryngeal mirror by flexible fiberoptic and rigid rod-lens laryngoscopy (including stroboscopy) and the resulting improvement in laryngeal visualization and documentation of examination has not resulted in a better definition of characteristic signs. Symptoms are often vague, and most are shared with other voice disorders. Under the circumstances, there is good reason to suppose that SLN dysfunction yields a clinical picture at least as heterogeneous as recurrent laryngeal nerve injury and a good deal more subtle. Faced with significant inconsistencies in clinical presentation, the clinician is hard-pressed to draw conclusions regarding prevalence, patterns of dysfunction, natural history, treatment, and even about its overall significance. EMG. used judiciously and complemented by frequency range testing, seems to hold more promise as a means of reliable diagnosis than laryngoscopic examination and may serve to resolve some of the confusion surrounding SLN dysfunction. It is equally important that the otolaryngologist guard against falling into the easy habit of attributing vocal disturbance that cannot be otherwise explained to SLN dysfunction in the absence of EMG evidence. If ambiguities surrounding SLN paralysis and paresis are to be clarified, diagnostic rigor is essential.

Laryngeal reinnervation.

Laryngeal reinnervation refers to any of a number of surgical procedures intended to restore neural connections to the larynx, which have usually been lost from some type of trauma (eg, surgical). The nerve function(s) to be restored may be those of the recurrent laryngeal nerve or its subdivisions, those of the superior laryngeal nerve, or both, and they may be motor or sensory. Several different donor nerves are available and have been described. The technique used may be direct end-to-end anastomosis (neurorrhaphy), direct implantation of a nerve ending into a muscle, the nerve-muscle pedicle technique, or muscle-nerve-muscle methods. These nerves and techniques may be combined in many ways. A number of new techniques have been reported in animal studies; however, the animal studies do not always predict the results of analogous surgeries in human patients. The historical and current perspectives on these techniques are discussed in this article.

Subglottic branch of the superior laryngeal nerve in the dog penetrates the cricoid cartilage.

The topographic anatomical study on the distribution pattern of the superior laryngeal nerve (SLN) in the larynx was studied in thirteen adult dogs. The ramus posterior of the SLN divides into two branches; the interarytenoid branch (IA) and the pharyngoesophageal branch (PE). The IA on both sides connect to the cricoid ganglion (CG) in the midline at the cranial border of the cricoid cartilage. Posterior glottic branches arise from the IA, run over the cricoid cartilage, and distribute fibers to the posterior wall of the glottis. Every specimen observed in the present study possessed the CG and the posterior glottic branches. The subglottic branch derives from the IA near the cricoid ganglion, and passes through the cricoid foramen (CF) (Yoshida, 1986). The subglottic branch distributes fibers to the subglottic mucous membrane covering the cricothyreoid ligament. The CF and the subglottic branch were observed on both sides of seven specimens out of thirteen dogs. They were also observed on only one side in three specimens, and were not detectable on either side in the three remaining specimens. The silver impregnation applied in the semimicroscopic dissection facilitated identification of the precise localization and the topographic arrangement of ganglia and nerve bundles.

Unilateral cricothyroid contraction and glottic configuration.

It is frequently stated that unilateral cricothyroid muscle (CT) paralysis can be diagnosed by physical examination, noting rotation of the glottis, and shortening and vertical displacement of the ipsilateral vocal fold. These signs, however, are inconsistently observed, and there is considerable controversy regarding the direction of glottic rotation. To determine the effects of CT contraction on three-dimensional glottic configuration, we performed computerized tomography on cadaver larynges before and after simulated CT contraction. Radiopaque makers were used to compute distances. Unilateral CT contraction equally increased the length of both membranous vocal folds, and rotated the posterior glottis less than 1 mm. CT contraction neither adducted the vocal processes, nor significantly their altered vertical level. These results suggest that unilateral CT paralysis cannot be diagnosed on the basis of any clinically apparent change in glottal configuration.

[Chronic muscular dysfunction of the bulbar innervation in hyperthyroidism: report of a case]. / Disfunção crônica da musculatura de inervação bulbar no hipertireoidismo: relato de caso.

The authors report a case of chronic bulbar muscular dysfunction in a thyrotoxic man, with complete remission of the symptoms after the use of propranolol, with and without concomitant use of propylthiouracil. Some aspects of this unique complication of hyperthyroidism are discussed.

Laryngeal reinnervation for bilateral vocal fold paralysis.

PURPOSE OF REVIEW: Laryngeal reinnervation for bilateral vocal fold paralysis (BVFP) patients is a promising technique to achieve good airway, although preserving a good quality of voice. On the other hand, the procedure is not simple. This review explores the recent literature on surgical technique and factors that may contribute to the success. RECENT FINDINGS: Research and literature in this area are limited due to variability and complexity of the nerve supply. The posterior cricoarytenoid (PCA) muscle also receives nerve supply from the interarytenoid branch. Transection of this nerve at the point between interarytenoid and PCA branch may prevent aberrant reinnervation of adductor nerve axons to the PCA muscle. A varying degree of regeneration of injured recurrent laryngeal nerves (RLN) in humans of more than 6 months confirms subclinical reinnervation, which may prevent denervation-induced atrophy. SUMMARY: Several promising surgical techniques have been developed for bilateral selective reinnervation for BVFP patients. This involves reinnervation of the abductor and adductor laryngeal muscles. The surgical technique aims at reinnervating the PCA muscle to trigger abduction during the respiratory cycle and preservation of good voice by strengthening the adductor muscles as well as prevention of laryngeal synkinesis.