Partial thyroarytenoid myectomy: an animal study investigating a proposed new treatment for adductor spasmodic dysphonia

Rabbit model with vocal fold hyperadduction

OBJECTIVE

Adductor spasmodic dysphonia (AdSD) is caused by hyperadduction of the vocal folds during phonation, resulting in a strained voice. Animal models are not yet used to elucidate this intractable disease because AdSD has a difficult pathology without a definitive origin. For the first step, we established an animal model with vocal fold hyperadduction and evaluated its validity by assessing laryngeal function.

METHODS

In this experimental animal study, three adult Japanese 20-week-old rabbits were used. The models were created using a combination of cricothyroid approximation, forced airflow, and electrical stimulation of the recurrent laryngeal nerves (RLNs). Cricothyroid approximation was added to produce a glottal slit. Thereafter, both RLNs were electrically stimulated to induce vocal fold hyperadduction. Finally, the left RLN was transected to relieve hyperadduction. The sound, endoscopic images, and subglottal pressure were recorded, and acoustic analysis was performed.

RESULTS

Subglottal pressure increased significantly, and the strained sound was produced after the electrical stimulation of the RLNs. After transecting the left RLN, the subglottal pressure decreased significantly, and the strained sound decreased. Acoustic analysis revealed an elevation of the standard deviation of F0 (SDF0) and degree of voice breaks (DVB) through stimulation of the RLNs, and degradation of SDF0 and DVB through RLN transection. Formant bands in the sound spectrogram were interrupted by the stimulation and appeared again after the RLN section.

CONCLUSION

This study developed a rabbit model with vocal fold hyperadduction . The subglottal pressure and acoustic analysis of this model resembled the characteristics of patients with AdSD. This model could be helpful to elucidate the pathology of the larynx caused by hyperadduction, and evaluate and compare the treatments for strained phonation.

Perioperative complications and safety of type II thyroplasty (TPII) for adductor spasmodic dysphonia

Type II thyroplasty (TPII) is one of the surgical options offered in the management of adductor spasmodic dysphonia (AdSD); however, there have been no detailed reports of its safety and associated complications during the perioperative period. Our aim was to assess the complications and safety of TPII. TPII was performed for consecutive 15 patients with AdSD from April 2012 through May 2014. We examined retrospectively the perioperative complications, the degree of surgical invasion, and recovery process from surgery. All patients underwent successful surgery under only local anesthesia. Vocal fold erythema was observed in 14 patients and vocal fold edema in 10 patients; however, all of them showed complete resolution within 1 month. No patient experienced severe complications such as acute airway distress or hemorrhage. Fourteen patients were able to have oral from the 1st postoperative morning, with the remaining patient able to have oral intake from the 2nd postoperative day. In addition, no patient experienced aspiration postoperatively. In conclusion, only minor complications were observed in association with TPII in this study. No dysphagia was observed postoperatively, which is an advantage over other treatments. The results of our study suggest that TPII is a safe surgical treatment for AdSD.

Liquid-type Botulinum Toxin Type A in Adductor Spasmodic Dysphonia: A Prospective Pilot Study

OBJECTIVES

Botulinum toxin (BTX) has been widely used to treat adductor spasmodic dysphonia (ADSD). Most commercially available forms of BTX require reconstitution before use, which may increase the risk of contamination and requires careful titration. Recently, a liquid-type BTX type A (BTX-A) has been developed, which should simplify the procedure and enhance its efficacy. Herein, we present a prospective pilot study to investigate the efficacy and safety of liquid-type BTX-A in the treatment of ADSD.

METHODS

Twenty-six consecutive liquid-type BTX-A injections were performed in 12 patients with ADSD. We included as a control group 34 consecutive patients with ADSD who had previously undergone 52 vocal fold injection procedures with freeze-dried-type BTX-A.

RESULTS

All patients in both groups had improvement of symptoms related to ADSD and period of normal voice. Most patients experienced breathiness, and the onset time, the peak response time, and the duration of breathiness were similar in both groups. The duration of effect (days) was 96.96 ± 18.91 and 77.38 ± 18.97 in the freeze-dried-type and the liquid-type groups, and the duration of benefit (days) was 80.02 ± 18.24 and 62.69 ± 19.73 in the freeze-dried-type and the liquid-type groups. To compare the efficacy between the freeze-dried-type and the liquid-type BTX-A, the sessions of the unilateral vocal fold injection were included and were categorized as group A (1 ~ 2 units BTX-A) and group B (2 ~ 3 units BTX-A), according to the dose per vocal fold. There was no significant difference of effect time between freeze-dried-type and liquid-type BTX-A groups. No adverse events related to BTX or vocal fold injection were reported.

CONCLUSIONS

Liquid-type BTX-A is safe and effective for the treatment of spasmodic dysphonia. With the advantages of simple preparation, storage, and reuse and animal protein-free constituents, liquid-type BTX-A may be a good option in the treatment of spasmodic dysphonia.

Transoral Approach to Laser Thyroarytenoid Myoneurectomy for Treatment of Adductor Spasmodic Dysphonia: Short-Term Results

Objectives:

The surgical technique for the resection of the recurrent laryngeal nerve for adductor spasmodic dysphonia (ASD) has high late failure rates. During the past decade, botulinum toxin has emerged as the treatment of choice for ASD. Although effective, it also has significant disadvantages, including a temporary effect and an unpredictable dose-response relationship. In this study we investigated the effectiveness of a new transoral approach to laser thyroarytenoid myoneurectomy for treatment of ASD.

Methods:

Fourteen patients with ASD underwent transoral laser myoneurectomy of bilateral thyroarytenoid muscles. Under general anesthesia, an operating microscope and a carbon dioxide laser were used to perform myectomy of the mid-posterior belly of bilateral thyroarytenoid muscles together with neurectomy of the terminal nerve fibers among the deep muscle bundles. Care was taken not to damage the vocalis ligaments, arytenoid cartilages, and lateral cricoarytenoid muscles. Preoperative and postoperative videolaryngostroboscopy and vocal assessments were studied.

Results:

The 13 patients who completed more than 6 months follow-up were enrolled in this study. Moderate and marked vocal improvement was achieved in 92% of the patients (12 of 13) after laser surgery during an average follow-up period of 17 months (range, 6 to 31 months). No vocal fold atrophy or paralysis was observed in any patient. None of the patients had a recurrence during the follow-up period.

Conclusions:

Transoral laser myoneurectomy of bilateral thyroarytenoid muscles is a relatively simple, effective, and valuable technique for the treatment of ASD. The durability of outcome achieved with this procedure is encouraging.

Lateral Cricoarytenoid Release: Development of a Novel Surgical Treatment Option for Adductor Spasmodic Dysphonia in a Canine Laryngeal Model

OBJECTIVE

To investigate the efficacy of a novel adductor muscle-releasing technique designed to decrease the force of vocal fold adduction, as a potential surgical therapy for patients with adductor spasmodic dysphonia (ADSD).

STUDY DESIGN

Experimental animal study.

METHODS

A canine laryngeal model was used to assess the acute and sustained efficacy of a lateral cricoarytenoid (LCA) muscle release. A total of 34 canine hemilaryngeal preparations were divided among 7 experimental groups. The LCA muscle was separated from its cricoid cartilage origin via an open, anterior, submucosal approach. The laryngeal adductory pressures (LAP) were assessed pre- and post-muscle release via direct recurrent laryngeal nerve stimulation. Measurements were repeated at 1.5, 3, or 6 months postoperatively. Another study evaluated release of the thyroarytenoid (TA) muscle from its thyroid cartilage origin.

RESULTS

Releasing the LCA muscle demonstrated a significant decrease in LAP acutely and was maintained at all 3 time points with the aid of a barrier (P < .05). Without the barrier, the LCA muscle reattached to the cricoid. Acute release of the TA muscle did not significantly decrease the LAP.

CONCLUSIONS

The proposed LCA release procedure may provide patients with a permanent treatment option for ADSD. However, longer-term studies and human trials are needed.

Minithyrotomy with radiofrequency-induced thermotherapy for the treatment of adductor spasmodic dysphonia

OBJECTIVES/HYPOTHESIS

A simple, safe and effective surgical alternative for treating adductor spasmodic dysphonia (ADSD) would appeal to many patients. This study evaluates a new option, using radiofrequency-induced thermotherapy (RFITT) of the thyroarytenoid muscle (TA) via the minithyrotomy approach to reduce the force of adduction.

METHODS

Fifteen dogs were used. In part 1, the optimal RFITT power settings, exposure time, probe location, and number of passes were determined. Part 2 compared laryngeal adductor pressures (LAPs) at baseline; immediately postintervention; and at 1, 3, or 6 months postintervention. Interventions included RFITT via the transcervical minithyrotomy approach (n = 15), transoral RFITT (n = 3), botulinum toxin (Botox) injection (n = 3), or no-intervention controls (n = 3). Postintervention induced phonation and histologic analyses were performed as well.

RESULTS

In the minithyrotomy RFITT group, the mean LAP was 30.3% of baseline immediately posttreatment. At 1, 3, and 6 months postoperatively, the mean LAPs were 24.9%, 44.8%, and 43.5%, respectively. Transoral RFITT reduced LAP to 56.6% of baseline immediately posttreatment, but returned to normal in the 1 and 3 month animals. The Botox injections dropped the LAP to 57% of baseline at 1 month, but returned to normal at 3 months. Mucosal waves, based on induced phonation stroboscopy, were present at the terminal date in all animals. Thirteen of 15 transcervical RFITT preparations (87%) showed no injury to the lamina propria, whereas 80% showed evidence of TA muscle atrophy and fibrosis.

CONCLUSION

Minithyrotomy RFITT is a feasible technique that shows encouraging long-term results for the potential treatment of patients with ADSD.

LEVEL OF EVIDENCE

N/A. Laryngoscope, 126:2325-2329, 2016.

Spasmodic dysphonia: let's look at that again

G. Paul Moore influenced the study of spasmodic dysphonia (SD) with his 1960 publication that examined the neurological, medical, and vocal fold behavior in a group of patients with adductor spasmodic dysphonia (ADSD). This review of advances in the diagnosis and treatment of SD follows a time line of research that can be traced in part to the early work of Moore et al. This article reviews the research in ADSD over the past 50 plus years. The capstone events that brought SD to its present day level of management by laryngologists and speech-language pathologists are highlighted. A look to the future to understand more of the disorder is offered for this debilitating disorder.

Surgical tips for type II thyroplasty for adductor spasmodic dysphonia: modified technique after reviewing unsatisfactory cases

CONCLUSION

Use of the titanium bridge, both at the top and bottom corners of the incised thyroid cartilage, is essential for success. Most importantly, these procedures should be done with minimal damage to the tissues involved, using fine instruments.

OBJECTIVES

Type II thyroplasty that aims at lateralization of the vocal folds for spasmodic dysphonia is a type of surgery that requires utmost surgical caution, because of the extremely delicate site for surgical intervention, critically sensitive adjustment, and difficult procedures to maintain the incised cartilages in a correct position.

PATIENTS AND METHODS

By means of a postoperative questionnaire and examinations, analyses were made of the relation in each case between the detailed surgical records and the outcomes in terms of subjective complaints, vocal features, and laryngeal as well as aerodynamic findings.

RESULTS

It was found that surgical failures or unsatisfactory results arise most frequently from certain clear mechanical faults. The critical procedures that most affected the results included: (1) incision and separation of the thyroid cartilage at the midline; (2) adjustment of separation width for optimal voice; (3) cartilage-perichondrium separation for holding an appropriate titanium bridge; and (4) installation and fixation of titanium bridges.

Treatment for spasmodic dysphonia: limitations of current approaches

PURPOSE OF REVIEW

Although botulinum toxin injection is the gold standard for treatment of spasmodic dysphonia, surgical approaches aimed at providing long-term symptom control have been advancing over recent years.

RECENT FINDINGS

When surgical approaches provide greater long-term benefits to symptom control, they also increase the initial period of side effects of breathiness and swallowing difficulties. Recent analyses of quality-of-life questionnaires in patients undergoing regular injections of botulinum toxin demonstrate that a large proportion of patients have limited relief for relatively short periods due to early breathiness and loss-of-benefit before reinjection.

SUMMARY

Most medical and surgical approaches to the treatment of spasmodic dysphonia have been aimed at denervation of the laryngeal muscles to block symptom expression in the voice, and have both adverse effects as well as treatment benefits. Research is needed to identify the central neuropathophysiology responsible for the laryngeal muscle spasms in order target treatment towards the central neurological abnormality responsible for producing symptoms.

Surgical treatment for adductor spasmodic dysphonia--efficacy of bilateral thyroarytenoid myectomy under microlaryngoscopy

CONCLUSIONS

Bilateral thyroarytenoid myectomy under microlaryngoscopy by the Muta method (TA myectomy) is a useful surgical treatment for adductor spasmodic dysphonia (ADSD), as a long-term-effect can be expected.

OBJECTIVE

Botulinum toxin (BT) injection is universally accepted as the first choice of treatment for ADSD. However, unfortunately it is not covered by National Health Insurance in Japan and therefore is not a common practice. So, various other therapeutic modalities have been reported. In the current study, we conducted bilateral TA myectomy on patients with ADSD and evaluated the results.

PATIENTS AND METHODS

Seven patients with ADSD who visited our department between 1999 and 2005 are described. The details of BT injection and the surgical procedure were described to the patients. As all seven patients wanted to undergo this surgical therapy, they all underwent bilateral TA myectomy.

RESULTS

The constriction was eliminated immediately after surgery and the patients became capable of smooth phonation. Hoarseness was recognized, but it began to ease after 1-2 months and was corrected to B grade 1-0 of the GRBAS scale approximately 6 months after the surgery. Improvement in the condition was noted in all seven patients according to evaluations based on the mora method. All patients are currently in the B grade 0.

The innervation of the posterior cricoarytenoid muscle: exploring clinical possibilities

Manipulation of the nerve supply to the posterior cricoarytenoid (PCA) muscle has potential for ameliorating the symptoms of some neurologic conditions such as abductor spasmodic dysphonia. The anatomy of the nerve supply to the PCA is better understood than in previous eras, but the anatomical understanding has not translated to clinical application yet. Microscopic dissection allowed the identification and measurement of the branches from the recurrent laryngeal nerves (RLNs) to the PCA in 43 human cadaver larynges. The cricothyroid (CT) joint was the primary landmark for measurement. Other structural measurements were also made on the larynges. All of the PCA muscles received innervation from the anterior division of the RLN. The number of direct branches from the RLN ranged from 1 to 5 (average 2.3) More than 70% of PCA muscles also received 1-3 branches off of the branch to the interarytenoid (IA) muscle. Less than half of PCA muscles received any kind of nerve branches from the posterior division of the RLN. Branches to the PCA most commonly departed the main RLN in its vertical segment and all entered the muscle from its deep surface. All branches departed the RLN within an average of 9.5mm from the CT joint; the branch to the IA occurs distal to this point. The innervation to the PCA is complex and redundant, and the segment of the RLN supplying those branches is difficult to expose safely. For these reasons, selective denervation or reinnervation procedures limited to the nerve branches may be technically difficult. When needing only to denervate the PCA, this can be accomplished by removing a portion of the PCA and the underlying nerve supply. Surgical technique should be based upon the understanding of the anatomy of the PCA muscle and its nerve supply.

Treatment of adductor-type spasmodic dysphonia by surgical myectomy: a preliminary report

OBJECTIVES

Despite the belief that it represents a central neurologic dysfunctional process, adductor-type spasmodic dysphonia without tremor is usually effectively treated by injection of botulinum toxin A; however, in most cases such injections must be repeated every few months. A promising new surgical procedure is herein reported.

METHODS

Under local anesthesia with intravenous sedation, a large laryngoplasty window is created, and under direct vision with intraoperative voice monitoring, fibers from the thyroarytenoid and lateral cricoarytenoid muscles are removed until breathiness occurs. The two sides are staged; that is, one side is done at a time, with surgery on the second side being performed 3 to 6 months after that on the first side, if needed.

RESULTS

This was a retrospective, unblinded study of 5 patients who underwent myectomy of the thyroarytenoid and lateral cricoarytenoid muscles. The preliminary results show improved voice fluency in all patients at 5 to 19 months of follow-up. There was no period of prolonged breathiness or dysphagia in any of the patients, and there were no surgical complications.

CONCLUSIONS

Myectomy of the thyroarytenoid and lateral cricoarytenoid muscles is a promising new surgical treatment for adductor-type spasmodic dysphonia that may effectively mimic "permanent" botulinum toxin injections.

Anatomy of the thyroarytenoid branch of the recurrent laryngeal nerve

OBJECTIVE

To determine the position and anatomic variability of the thyroarytenoid (TA) branch of the recurrent laryngeal nerve (RLN).

METHODS

The RLN on 13 human cadaver specimens (24 sides) was dissected to the termination of the TA branch in the TA muscle. A pin was placed at the inferior aspect of the thyroid cartilage at the inferior tubercle. Using a caliper, the distance from the pin to the TA branch of the RLN was measured. The direction of the nerve and number of branches were recorded.

RESULTS

The average distance to the TA branch of the RLN is 4.23 mm with a standard deviation of 2.86 mm. The median distance is 3.75 mm. Most of the specimens fell in a range of 1 to 4 mm. Overall, 54% of the nerves traveled in a horizontal direction, but vertical and oblique orientations were observed. About 20% of specimens demonstrated branching of the TA nerve.

CONCLUSION

Measuring 4 mm from the inferior tubercle along a perpendicular line from the thyroid tubercle on the inferior border of the thyroid cartilage provides a good estimate of the location of the TA branch of the RLN. This information is useful when creating a posterior thyrotomy for TA neurectomy for patients with adductor spasmodic dysphonia. Knowledge of the course and possible branching of the nerve, will aid in localizing the nerve as well as ensuring adequate resection.

Bipolar radiofrequency-induced thermotherapy (rfitt) for the treatment of spasmodic dysphonia. A report of three cases

The symptoms of adductor spasmodic dysphonia are most commonly palliated by periodic botulinum toxin injections. The need for repeated injections, difficulty in obtaining injections and cost make this form of treatment intolerable for some patients. To address these concerns, we propose a new treatment approach utilizing trans-oral recurrent nerve coagulation. The goal is to weaken the force of laryngeal closure during spasms by creating fibrosis of the terminal branches of one recurrent nerve through coagulation. Under general anesthesia without paralysis, an electrical stimulator is used to identify the region within the thyroarytenoid muscle that produces the greatest contraction with minimal stimulation. The radiofrequency laryngeal probe or electrocautery device is introduced into this position, and energy is delivered. The location of the region of maximal stimulation is usually just lateral and anterior to the vocal process of the arytenoids. Between 1989 and 2000, seven patients were treated with electrocautery. To achieve remission of spasms, three patients needed three sessions, four needed two sessions and one only one session. Since 2001, three patients have achieved remission of spasms with a single treatment with radiofrequency during which 80 J was delivered. Voice results are comparable to those obtained with botulinum toxin. Initially, the voice is breathy and laryngeal examination shows complete vocal fold immobility. After 1-2 months, the voice improves and examination reveals unilateral hypomobility. Trans-oral recurrent nerve coagulation is an effective alternative to botulinum toxin injections.

Longitudinal effects of botulinum toxin injections on voice-related quality of life (V-RQOL) for patients with adductory spasmodic dysphonia

Adductory spasmodic dysphonia is a focal dystonia of laryngeal muscles. Patients with this disorder typically have severe vocal difficulties, with significant functional, social, and emotional consequences. There is no widely accepted cure for this condition, however, botulinum toxin injections of the thyroarytenoid muscles are considered by most voice clinicians to be the state of the art treatment. Based on extensive experience treating patients for adductory spasmodic dysphonia, we feel that traditional means of voice assessment do not adequately measure either the disease severity or the treatment outcomes. That is, listening to or acoustically analyzing limited phonatory samples does not capture the functional, social, and emotional consequences of this disorder. These consequences will be reflected in a patient's voice-related quality of life (V-RQOL). Using a validated voice outcomes instrument, the V-RQOL Measure, the purpose of this study was to quantify longitudinal changes in the V-RQOL of patients with adductory spasmodic dysphonia who are undergoing botulinum toxin injections. Twenty-seven consecutive new patients presenting with dysphonia to our institution during an 18-month period were diagnosed with adductory spasmodic dysphonia, and treated patients were evaluated prospectively using the V-RQOL Measure. Results indicated that (1) V-RQOL was initially very low for these patients, (2) botulinum toxin injections improved it significantly for each injection cycle studied, and (3) the magnitude of the treatment effect appears to change across injections.

Thyroid cartilage and vocal fold reduction: a new phonosurgical method for male-to-female transsexuals

To date, there is a paucity of literature on surgery to alter vocal pitch in male-to-female transsexuals. The currently available pitch-raising surgical techniques yield neither a good long-term result nor a high enough pitch to simulate a female voice. We investigated a new procedure to alter vocal pitch in 6 male-to-female transsexuals. The principle is to shorten and increase tension on both vocal folds by composite resection of a vertical strip of the anterior thyroid cartilage along with a segment of vocal fold. This resulted in a satisfactory pitch alteration from an average of 147 Hz before operation to 315 Hz afterward. In addition to a marked pitch elevation, all patients were particularly pleased with the softness of the voice and the simultaneous loss of the prominentia laryngea (Adam's apple). The longest follow-up was 6 years. In conclusion, thyroid cartilage and vocal fold reduction is an effective method for long-term alteration of voice in male-to-female transsexuals.

Neurolaryngology: past, present, and future

Neurolaryngology is the study and management of disorders that impair neural control of the larynx and pharynx in breathing, swallowing, and speech. Advances in functional endoscopy and fluoroscopy and increased understanding of neurophysiology have greatly facilitated the development of this discipline. The empiric observations of effective therapies have been equally important, however. In comparison to other fields of medicine, neurolaryngology is a relatively young discipline, and much remains to be discovered and developed.

Long-term follow-up of recurrent laryngeal nerve avulsion for the treatment of spastic dysphonia

Long-term follow-up of 3 to 7 years is reported on 18 patients who had undergone recurrent laryngeal nerve avulsion (RLNA) for the treatment of adductor spastic dysphonia (SD). Data on neural regrowth after previous recurrent laryngeal nerve section (RLNS) are presented in 2 of these 18 patients. We introduced RLNA as a modification of standard RLNS to prevent neural regrowth to the hemiparalyzed larynx and subsequent recurrence of SD. We have treated a total of 22 patients with RLNA, and now report a 3- to 7-year follow-up on 18 of these 22 patients. Resolution of symptoms was determined by routine follow-up assessment, perceptual voice analysis, and patient self-assessment. Sixteen of 18, or 89%, had no recurrence of spasms at 3 years after RLNA as determined at routine follow-up. Two of the 16 later developed spasms after medialization laryngoplasty for treatment of weak voice persistent after the avulsion. This yielded a total of 14 of 18, or 78%, who were unanimously judged by four speech pathologists to have no recurrence of SD at the longer follow-up period of 3 to 7 years. Two of these 4 patients were judged by all four analysts to have frequent, short spasms. The other 2 were judged by two of four analysts to have seldom, short spasms. Three of 18 patients presented with recurrent SD after previous RLNS. At the time of subsequent RLNA, each patient had evidence of neural regrowth at the distal nerve stump as demonstrated by intraoperative electromyography and histologic evaluation of the distal nerve stump. One remained free of SD following RLNA, 1 was free of spasms at 4 years after revision avulsion but developed spasms after medialization laryngoplasty, and the final patient developed spasms 3.75 years after revision RLNA. Medialization laryngoplasty with Silastic silicone rubber was performed in 6 of 18, with correction of postoperative breathiness in all 6, but with recurrence of spasm in 3. Spasms resolved in 1 of these with downsizing of the implant. We conclude that RLNA represents a useful treatment in the management of SD in patients not tolerant of botulinum toxin injections.