Laryngeal Reinnervation by Ansa Cervicalis Nerve Implantation for Unilateral Vocal Cord Paralysis in Humans

Systematic review and meta-analysis of laryngeal reinnervation techniques in adults with unilateral and bilateral vocal fold palsies

OBJECTIVE

To evaluate the outcomes of reinnervation techniques for the treatment of adult unilateral vocal fold paralysis and bilateral vocal fold paralysis.

METHODS

A literature review was conducted in the Embase and Medline databases in English, with no limitations on the publication date. The outcome parameters of interest included visual, subjective perceptual, acoustic, aerodynamic analysis and electromyography. A meta-analysis with a random-effects model and inverse variance was calculated.

RESULTS

The systematic Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach resulted in 27 studies, totalling 803 patients (747 unilateral cases and 56 bilateral cases). Thyroid cancer and/or surgery had caused unilateral vocal fold paralysis in 74.8 per cent of cases and bilateral vocal fold paralysis in 69.6 per cent of cases. Statistically significant improvements in patients were observed for voice, deglutition and decannulation (bilateral vocal fold paralysis). Meta-analysis of 10 reinnervation techniques was calculated for the maximum phonation time of 184 patients.

CONCLUSION

Reinnervation was shown to improve voice, swallowing and decannulation, but studies lacked control groups, limiting generalisability. Larger studies with controls are needed.

Timing of Ansa Cervicalis-to-recurrent Laryngeal Nerve Reinnervation: A Systematic Review

BACKGROUND

Ansa cervicalis-to-recurrent laryngeal nerve anastomosis (ARA) is an established technique for the treatment of recurrent laryngeal nerve (RLN) injury after head and neck surgery. However, the optimal timing of ARA remains unclear, and the evidence bases for ARA performed at each timepoint after RLN injury have not previously been clearly distinguished. We conducted a systematic review of the literature to evaluate the efficacy of ARA performed at different timepoints on postoperative voice outcomes.

METHODS

A review of English-language journal articles published in the last 20 years was undertaken on three electronic databases: Ovid MEDLINE, PubMed and Embase. Studies with a focus on paediatric RLN injury, bilateral RLN injury, ansa cervicalis anatomy and non-ARA techniques alone were excluded.

RESULTS

Twenty eight articles were included in the review. ARA was performed as a delayed surgery in 16/28 studies (57%), while immediate ARA was utilized in 14/28 studies (50%). On qualitative synthesis, delayed ARA was shown to be effective in improving patient-reported, subjective observer-reported and objective observer-reported voice outcomes. Likewise, a substantial body of evidence was identified demonstrating postoperative voice improvement with immediate ARA. On direct comparison of timepoints, some benefit was shown for early delayed ARA relative to late delayed operations, while no comparative data for immediate versus delayed repair were available in the literature.

CONCLUSIONS

ARA at both delayed and immediate timepoints is effective in the treatment of patients with RLN injury after head and neck surgery. The timing of ARA may have some influence on its efficacy, with early delayed repair potentially associated with superior outcomes to late delayed operations, and immediate ARA offering several practical advantages relative to delayed repair. Further comparative studies are required to better characterize the optimal timing of ARA after RLN injury.

Care and Management of Voice Change for Thyroid Surgery: Korean Society of Laryngology, Phoniatrics and Logopedics Clinical Practice Guideline

Voice change is a common complaint after thyroid surgery and has significant impacts on quality of life. The Korean Society of Laryngology, Phoniatrics, and Logopedics set up a task force team to establish guideline recommendations on education, care, and management related to thyroid surgery. The guideline recommendations include preoperative voice education, management of anticipated voice change during surgery, and comprehensive voice care after thyroid surgery, including in-depth information and up-to-date knowledge based on validated literature. The committee constructed 14 key questions (KQ) in three categories: preoperative (KQ1-2), intraoperative (KQ 3-8), and postoperative (KQ 9-14) management and developed 18 evidence-based recommendations. The Delphi survey reached an agreement on each recommendation. Detailed evidence profiles are presented for each recommendation. The level of evidence for each recommendation is classified into high, moderate, and low-quality. The recommendation's strengths are adjusted to consider the level of evidence resulting in the recommendation and are divided into strong and weak. The guidelines are primarily targeted toward physicians who treat thyroid surgery patients and speech-language pathologists participating in patient care. These guidelines will also help primary care physicians, nurses, healthcare policymakers, and patients improve their understanding of voice changes and voice care after thyroid surgery.

TrkA inhibitor promotes motor functional regeneration of recurrent laryngeal nerve by suppression of sensory nerve regeneration

Recurrent laryngeal nerve (RLN) injury, in which hoarseness and dysphagia arise as a result of impaired vocal fold movement, is a serious complication. Misdirected regeneration is an issue for functional regeneration. In this study, we demonstrated the effect of TrkA inhibitors, which blocks the NGF-TrkA pathway that acts on the sensory/automatic nerves thus preventing misdirected regeneration among motor and sensory nerves, and thereby promoting the regeneration of motor neurons to achieve functional recovery. RLN axotomy rat models were used in this study, in which cut ends of the nerve were bridged with polyglycolic acid-collagen tube with and without TrkA inhibitor (TrkAi) infiltration. Our study revealed significant improvement in motor nerve fiber regeneration and function, in assessment of vocal fold movement, myelinated nerve regeneration, compound muscle action potential, and prevention of laryngeal muscle atrophy. Retrograde labeling demonstrated fewer labeled neurons in the vagus ganglion, which confirmed reduced misdirected regeneration among motor and sensory fibers, and a change in distribution of the labeled neurons in the nucleus ambiguus. Our study demonstrated that TrkAi have a strong potential for clinical application in the treatment of RLN injury.

An Anatomic Variant of the Ansa Cervicalis Precluding Its Use as a Donor Nerve

BACKGROUND

The ansa cervicalis is useful for cranial nerve repair, and may be harvested without apparent morbidity. Herein we report an unusual and surgically relevant anatomic variant of the ansa cervicalis.

METHODS

An adult male with left parotid adenoid cystic carcinoma underwent parotidectomy with upper-division facial nerve resection and planned interposition repair using the ansa cervicalis. The ipsilateral hypoglossal nerve was identified, together with a descending branch producing strap muscle contraction when stimulated. This presumed descendens hypoglossi was unusually large in caliber; further dissection revealed continuity with the vagus nerve.

RESULTS

Ansa cervicalis harvest was aborted when its separation from vagus nerve epineurium was not possible. The sural nerve was alternatively harvested. The patient awoke with left vocal fold palsy, which completely resolved within 3 months.

CONCLUSION

Anatomic variants of the ansa cervicalis exist that may preclude graft harvest and place the vagus nerve at risk of inadvertent injury.

Does Dysphagia Improve Following Laryngeal Reinnervation for Treatment of Hoarseness in Unilateral Vocal Fold Paralysis?

PURPOSE

There are many reports of the efficacy of laryngeal reinnervation on voice, but there is a paucity of literature regarding its impact on swallowing function. The goal of this study was to explore the impact of laryngeal reinnervation on swallowing outcomes among unilateral vocal fold paralysis (UVFP) patients.

METHODS

We reviewed 22 UVFP cases treated with laryngeal reinnervation at our institution. Ten patients had complete datasets, including Eating Assessment Tool (EAT-10) scores and appropriate follow-up. Wilcoxon signed-rank test was used to compare pre- and postoperative scores.

RESULTS

Over the study period, 10 cases (mean age 45.7 ± 13.3 years; 6/10 men) with UVFP underwent ansa cervicalis to recurrent laryngeal nerve anastomosis (6/10) or nerve-muscle pedicle procedure (4/10). The median time between injury and surgical reinnervation was 12.4 months (range 2.7-88.5 months). Based on EAT-10 scores 6/10 patients were found to have dysphagia. Of these, four improved their score after surgery, one remained stable, and one deteriorated. The median EAT-10 score of these patients improved from 13 to 7 after surgery, but this difference was not statistically significant (P = 0.138).

CONCLUSION

Laryngeal reinnervation procedure has the potential for restoring a near normal voice in UVFP. Laryngeal reinnervation of the vocal fold may be associated with a tendency toward improvement in the EAT-10 score in patients after surgery for hoarseness in the setting of UVFP.

Long-term quality of voice is usually acceptable after initial hoarseness caused by a thyroidectomy or a parathyroidectomy

Background

Vocal cord (VC) palsy following a thyroidectomy or parathyroidectomy can result in significant morbidity for the patient. We aimed to investigate the incidence of VC palsy in a tertiary referral Institution, track the management of these cases and record the long-term outcomes and VC recovery rates.

Methods

Retrospective review of all thyroidectomy/parathyroidectomy operations performed over 11 years. Patients with an unequivocal hoarse voice postoperatively were included. We analysed the patient's clinical characteristics and voice outcomes, operative, pathology and laryngoscopy reports during their follow-up.

Results

Ten patients fitted the inclusion criteria and were analysed. Median age at date of operation was 47.5 years (range, 16-81 years) and the M:F ratio was 1:2.3 (M:3, F:7). The median FU was 62.5 months (range, 12-144 months). The median hospital stay was 1.5 days (range, 1-87 days). There were 7 recurrent laryngeal nerve (RLN) injuries by manipulation, 1 case of RLN resection, 1 inadvertent division (with primary nerve repair) and 1 RLN was shaved off the thyroid. Long-term voice outcomes for the 7 patients with an RLN manipulation injury were: 3/7 patients had normal voice, 3/7 had moderate hoarseness and 1/7 had long-term hoarseness. The long-term voice outcome of the patient with RLN shaving off the thyroid gland was excellent while the 2 remaining patients (RLN resection and inadvertent division) needed 12 and 18 months respectively to achieve a normal quality of voice. Four out of the 10 patients had permanent VC palsy in the long-term and their voice outcomes varied: 1 patient had a normal voice, 2 patients had moderate hoarseness and 1 patient had persistent hoarseness. Only 1/10 patients did not show any voice improvement after 12 months.

Conclusions

In the vast majority of cases post-operative hoarseness due to RLN palsy improves in the long-term, albeit voice may not return completely to normal.

Perspectives on voice treatment for unilateral vocal fold paralysis

PURPOSE OF REVIEW

Unilateral vocal fold paralysis (UVFP) is a common cause of neurogenic dysphonia resulting in glottal insufficiency. To restore glottal sufficiency and reduce the presenting dysphonia, treatment involving either surgical intervention, voice therapy or a combination of the two is typically provided. Currently, there is no consensus for the most effective voice treatment for UVFP. This results in an inability to compare current studies, and a lack of treatment effectiveness for the management of UVFP. This study aims to review the most recent literature for the management of dysphonia due to UVFP to establish the current evidence base for voice treatment options.

RECENT FINDINGS

There was found to be a lack of consistency in the rationale, selection and timing of the surgical intervention and/or voice therapy being provided for patients with UVFP.

SUMMARY

Further consensus is required for the rationale and selection of voice treatment prescriptions for the management of UVFP in order to improve treatment effectiveness and voice outcomes in patients with UVFP.

Role of reinnervation in the management of recurrent laryngeal nerve injury: current state and advances

PURPOSE OF REVIEW

To present the current state of knowledge concerning different laryngeal reinnervation procedures for unilateral and bilateral vocal palsy.

RECENT FINDINGS

Recent reports show positive outcomes on both unilateral and bilateral reinnervations. The phrenic nerve is the most commonly used donor for bilateral vocal palsy, but use of the superior laryngeal nerve has also been suggested.

SUMMARY

Reinnervation of the larynx is a complex undertaking that can be performed by ENT surgeons with skills in microsurgery. Advances in this this field represent a paradigm shift in laryngeal rehabilitation and a prerequisite for laryngeal transplantation. Advances in basic understanding of nerve regeneration and in particular the need to surgically manage competitive reinnervation make the results of laryngeal reinnervation more predictable.

One hundred years of external approach medialisation thyroplasty

It has been 100 years since Erwin Payr first developed an operation to improve the effects of a paralysed vocal fold, and operations based on this technique are still in use today. This technique, medialisation thyroplasty, aims to improve the symptoms caused by vocal fold palsy by realigning the lateralised vocal fold into the midline.

Whilst the effects of vocal fold palsy were recognised in antiquity, it was only with the development of indirect laryngoscopy in the late nineteenth century that the vocal fold paralysis could be identified as an aetiology for poor phonation and dysphagia. Payr, in 1915, was the first to perform a recognisable form of medialisation thyroplasty, which was further developed in the early twentieth century, but medialisation thyroplasty did not begin to be widely used until the development of the modern technique by Isshiki et al., in 1974.

Since then, medialisation thyroplasty has continued to be developed and is currently the most widely used technique for correcting the effects of vocal fold palsy. However, a wide array of therapeutic options is now available for vocal fold palsy and it is impossible to say whether or not medialisation thyroplasty will still be used in another 100 years.

Some unusual types of formation of the ansa cervicalis in humans and proposal of a new morphological classification

Ansa cervicalis (ansa hypoglossi) is a peripheral nerve structure-the primary choice for laryngeal reinnervation. Because the ansa formation is quite variable in humans, it is an object of a number of proposed classifications. Two interesting cases of formation of the ansa cervicalis were found during routine anatomical dissections. In the first case the unusual ansa had three basic roots-a superior one from the hypoglossal nerve, an aberrant middle root from the vagus nerve and an inferior root, coming from the cervical ventral branches. In the second case an ansa was described having roots from the vagus nerve and cervical ventral branches. Based on the reported variations and extensive review of the pertinent literature, a new morphological classification of the ansa cervicalis formation in human is proposed here.

[Treatment of glottal gap]

Glottal gaps can be either physiological or pathological. The latter are multifactorial, predominantly organic in origin and occasionally functional. Organic causes include vocal fold paralysis or scarring, as well as a deficiency or excess of tissue. In addition to loss of the mucosal wave, the degree of hoarseness is primarily determined by the circumferential area of the glottal gap. It is thus important to quantify the extent of glottal insufficiency. Although a patient's symptoms form the basis for treatment decisions, these may be subjective and inadequately reflected by the results of auditory-perceptual evaluation, voice analysis and voice performance tests. The therapeutic approach should always combine phonosurgery with conventional voice therapy methods. Voice therapy utilises all the resources made available by the sphincter model of the aerodigestive tract and knowledge on the mechanism of voice production. The aim of phonosurgery is medialization, reconstruction or reinnervation by injection laryngoplasty or larynx framework surgery. These different methods can be combined and often applied directly after vocal fold surgery (primary reconstruction). In conclusion, the techniques described here can be effectively employed to compensate for glottal gaps.

Nerve-muscle-endplate band grafting: a new technique for muscle reinnervation

BACKGROUND

Because currently existing reinnervation methods result in poor functional recovery, there is a great need to develop new treatment strategies.

OBJECTIVE

To investigate the efficacy of our recently developed nerve-muscle-endplate band grafting (NMEG) technique for muscle reinnervation.

METHODS

Twenty-five adult rats were used. Sternohyoid (SH) and sternomastoid (SM) muscles served as donor and recipient muscle, respectively. Neural organization of the SH and SM muscles and surgical feasibility of the NMEG technique were determined. An NMEG contained a muscle block, a nerve branch with nerve terminals, and a motor endplate band with numerous neuromuscular junctions. After a 3-month recovery period, the degree of functional recovery was evaluated with a maximal tetanic force measurement. Retrograde horseradish peroxidase tracing was used to track the origin of the motor innervation of the reinnervated muscles. The reinnervated muscles were examined morphohistologically and immunohistochemically to assess the extent of axonal regeneration.

RESULTS

Nerve supply patterns and locations of the motor endplate bands in the SH and SM muscles were documented. The results demonstrated that the reinnervated SM muscles gained motor control from the SH motoneurons. The NMEG technique yielded extensive axonal regeneration and significant recovery of SM muscle force-generating capacity (67% of control). The mean wet weight of the NMEG-reinnervated muscles (87% of control) was greater than that of the denervated SM muscles (36% of control).

CONCLUSION

The NMEG technique resulted in successful muscle reinnervation and functional recovery. This technique holds promise in the treatment of muscle paralysis.

Systematic review of laryngeal reinnervation techniques

OBJECTIVE: To systematically review outcomes of reinnervation techniques for the management of unilateral vocal fold paralysis (UVFP).

DATA SOURCES: Medline and Cochrane databases for English-language studies published between 1966 and 2009 on the surgical management of UVFP.

REVIEW METHODS: Studies were excluded if they reported on bilateral vocal fold paralysis, used nonhuman subjects, or did not assess clinical outcomes. Outcomes of interest were visual analysis, acoustic analysis, perceptual analysis, and electromyography.

RESULTS: Of 686 initial studies, 14 studies encompassing 329 patients were eligible for analysis. All studies had a case-series design. Of reported patients, 60.2 percent were men, with mean age of 51 years (range, 12-79 years). The most common reinnervation technique was ansa cervicalis-to-recurrent laryngeal nerve (RLN), which was most commonly performed after thyroidectomy (43.5%). Other techniques with reportable outcomes included primary RLN anastomosis, ansa-to-RLN combined with cricothyroid muscle-nerve-muscle pedicle, ansa-to-thyroarytenoid neural implantation, ansa-to-thyroarytenoid neuromuscular pedicle, and hypoglossal-to-RLN. Median postsurgical follow-up was 12 months, and mean time to first signs of reinnervation was 4.5 months (SD 2.9 months). Visual analysis of glottic gap showed the greatest mean improvement with ansa-to-RLN, from 2.25 (SD 0.886) to 0.75 (SD 0.886) mm ( P < 0.01). Acoustic analysis showed greatest improvement with neural implantation, with a change in mean phonation time from seven (SD 1.22) to 16 (SD 5.52) seconds ( P < 0.01). Perceptual analysis and electromyography demonstrated improvement in all studies.

CONCLUSION: Reinnervation is effective in the management of UVFP, although the specific method may be dictated by anatomical limitations. Prospective studies utilizing uniform and consistent outcome parameters are necessary.

Laryngeal reinnervation with nerve-nerve anastomosis versus laryngeal framework surgery alone: A comparison of safety

OBJECTIVE: To characterize any additional risks and rate of complication associated with laryngeal reinnervation in comparison to traditional laryngeal framework surgery.

DESIGN: Retrospective chart review over a 5-year period.

RESULTS: A total of 16 reinnervation procedures were performed to rehabilitate a paralyzed vocal fold. Of the 16 procedures, 12 (75%) were combined with arytenoid adduction. One reinnervation was aborted due to presence of scar and vascular malformation in the tracheal-esophageal groove. There were no major complications (airway obstruction or death). There were no cases of prolonged dysphagia or aspiration pneumonia; there was one wound infection (6%). Endoscopic findings postoperatively included pharyngeal ecchymoses in three patients (19%), all of whom underwent a simultaneously performed arytenoid adduction. There was a similar incidence of minor complications in traditional framework surgery performed without reinnervation ( P > 0.05).

CONCLUSION: Laryngeal reinnervation, alone or in combination with laryngeal framework surgery, does not appear to add significant perioperative morbidity. This is the first report to document the safety of laryngeal reinnervation by nerve-nerve anastomosis.

Ansa Cervicalis-to-Recurrent Laryngeal Nerve Anastomosis for Unilateral Vocal Fold Paralysis: Experience of a Single Institution

Objectives:

One treatment option for unilateral vocal fold paralysis (UVFP) is ansa cervicalis-to-recurrent laryngeal nerve (ansa-RLN) anastomosis to provide reinnervation to the affected vocal fold. The advantages of this treatment approach are that it 1) provides vocal fold tone, bulk, and tension, 2) is technically simple, and 3) does not preclude other medialization procedures. We present all patients who have undergone ansa-RLN anastomosis for UVFP at our institution.

Methods:

An Institutional Review Board-approved retrospective chart review was performed to include all patients who had undergone an ansa-RLN anastomosis procedure for UVFP at our institution. Data from clinical and endoscopic laryngoscopy with stroboscopy were recorded. Statistical analysis was performed on visual and perceptual vocal data.

Results:

A total of 46 patients were included in the study. Stroboscopic analysis and perceptual vocal evaluation was performed in a blinded fashion on the 21 patients who had preoperative and postoperative stroboscopy. Severity, roughness, breathiness, and strain all improved significantly over time. Glottic closure, vocal fold edge, and supraglottic effort all significantly improved after operation. Of the 38 patients with at least 3 months of follow-up, all except 1 demonstrated evidence of reinnervation.

Conclusions:

This technique for treating UVFP results in significant improvements in patients' voice and on visual examination.

Unilateral arytenoid adduction improves voice in a patient with bilateral vocal fold immobility

Bilateral vocal fold immobility (BVFI) due to prolonged endotracheal intubation resulted in aphonia without any airway morbidity and was treated by several reconstructive procedures. Laryngeal reinnervation and silicone implantation failed to medialize one of those two fixed cords. Arytenoid adduction (AA) eventually achieved this goal. To select an optimal reconstructive procedure, a careful perusal of the history and head and neck examination including laryngeal electromyography, are necessary to determine the causes. AA procedure played an essential clinical indication in this study, not just an adjunct to the medialization laryngoplasty as usual. Since both the vocal cords positions were ranked as lateral positions subjectively, the full adduction for one of those two fixed vocal cords was performed without significant airway obstruction. The practice in this study provided an experience in correcting the voice in patients with BVFI. We need further experience to medialize the vocal cord in an appropriate magnitude since its counterpart may position variously and compromise the airway.