Electrophysiologic monitoring of the recurrent laryngeal nerves may not predict bilateral vocal fold immobility after thyroid surgery

Two cases of bilateral vocal fold immobility (VFI) after identification and preservation of the recurrent laryngeal nerves (RLNs) required tracheotomy until vocal fold recovery. The first patient underwent thyroid surgery without preoperative or postoperative evaluation of the vocal folds, administration of postoperative intravenous steroids, or electrophysiologic monitoring of the RLNs, whereas the second patient underwent a thyroid procedure in which all of the aforementioned were executed. Preoperative and postoperative clinical evaluation of the RLNs is strongly suggested in patients undergoing thyroid surgery, especially revision surgery. Patients potentially undergoing total thyroidectomy should be counseled about the remote chance of airway obstruction and should be properly selected for this operation. Subclinical stretching of the RLNs or ischemia from the endotracheal tube cuff can result in unilateral VFI, and rarely bilateral VFI, requiring reintubation, tracheotomy, or vocal fold lateralization. Electrophysiologic monitoring may not always predict bilateral VFI.     

Recurrent Laryngeal Nerve Electrophysiologic Monitoring in Thyroid Surgery: The Standard of Care?

Reports in the literature suggest that the rate of transient and permanent vocal fold immobility (VFI) after thyroid surgery is 4% to 7% and 1% to 4%. The intraoperative use of nerve integrity monitors has been advocated to reduce the incidence of VFI during thyroid surgery. The purpose of this study was to compare postoperative VFI after unmonitored and monitored thyroid surgical procedures. The charts of 136 consecutive patients who underwent thyroid surgery from 1998 to 2003 were retrospectively surveyed. Fifty-four patients had total thyroidectomies, bringing the total recurrent laryngeal nerves (RLNs) dissected to 190. Three of 190 (1.6%) and 7 of 190 (3.7%) RLNs dissected had permanent and transient vocal fold dysfunction. Overall, 107 RLNs were unmonitored compared with 83 RLNs that were monitored. Unmonitored and monitored RLNs had a 4 of 83 (4.8%) versus 3 of 107 (2.8%) rate of transient VFI (P > 0.05). Unmonitored and monitored RLNs had a 1 of 107 (0.9%) versus 2 of 83 (2.4%) rate of permanent VFD (P > 0.05). Electrophysiologic RLN monitoring was not demonstrated in this study to reduce the incidence of transient or permanent VFI after thyroid surgery. Electrophysiologic RLN integrity does not always translate into clinical postoperative vocal fold mobility. Electrophysiologic RLN monitoring may support that the RLN was not severed in the patient with postoperative VFI.     

Combination thyroplasty and the “twisted larynx:” combined type IV and type I thyroplasty for superior laryngeal nerve weakness

Vocal cord medialization through Isshiki type I thyroplasty is part of the standard approach for patients with unilateral vocal cord immobility secondary to recurrent laryngeal nerve paralysis. However, several other modalities have been used to treat the symptomatic “twisted” larynx caused by unilateral superior laryngeal nerve weakness. The Isshiki type IV thyroplasty (cricothyroid approximation) specifically addresses cricothyroid muscle weakness, but, canine studies at the Mayo Clinic demonstrated a trend toward decreased acoustic power and sound intensity with simulated cricothyroid activity. Thus it is reasoned that addition of an ipsilateral type I thyroplasty should help compensate for this power loss.Using videostroboscopic and acoustic analysis, 9 patients with unilateral superor laryngeal nerve weakness were treated with combination type IV and type I thyroplasty. Subjective dysphonia and objective visual and acoustic measurements revealed postoperative improvement in most patients. The combination type IV and type I thyroplasty is recommended for surgical treatment of patients with superior laryngeal nerve weakness, because it addresses cricothyroid muscle weakness without compromising vocal power.     

Vocal Fold Paralysis Following Radiotherapy for Nasopharyngeal Carcinoma: Laryngeal Electromyography Findings

Laryngeal electromyography was used to study the pattern of neurological injury in three patients with unilateral vocal fold paralysis following radiotherapy for nasopharyngeal carcinoma. The thyroarytenoid and cricothyroid muscles were assessed to give an indication of recurrent and superior laryngeal nerve function. Two patients demonstrated both recurrent and superior laryngeal neuropathy suggesting injury at the skull base. The other patient had only recurrent laryngeal neuropathy indicating more distal involvement. Subclinical neuropathic changes were seen in two cases on the side contralateral to the vocal fold paralysis. These patients may be at increased risk of developing bilateral vocal fold paralysis and potentially life-threatening airway obstruction. Long-term follow-up is recommended for such patients, especially if medialization thyroplasty is being considered. This is the first report describing the use of electromyography to determine the pattern of nerve injury in patients with vocal fold paralysis following head and neck radiotherapy.     

Functional reinnervation of vocal folds after selective laryngeal adductor denervation-reinnervation surgery for spasmodic dysphonia

Selective laryngeal adductor denervation-reinnervation surgery (SLAD-R) offers a viable surgical alternative for patients with adductor spasmodic dysphonia refractory to botulinum toxin injections. SLAD-R selectively denervates the symptomatic thyroarytenoid muscle by dividing the distal adductor branch of the recurrent laryngeal nerve (RLN), and preventing reinnervation, by the proximal RLN and maintaining vocal fold bulk and tone by reinnervating the distal RLN with the ansa cervicalis. We present a patient who had previously undergone successful SLAD-R but presented 10 years postoperatively with a new regional dystonia involving his strap muscles translocated to his reinnervated larynx by his previous ansa-RLN neurorraphy. The patient's symptomatic vocal fold adduction resolved completely on division of the ansa-RLN neurorraphy confirming successful selective functional reinnervation of vocal fold adductors by the ansa cervicalis.     

Acoustic analysis of the speaking voice after thyroidectomy

Voices of 47 female patients were analyzed before and after thyroidectomy, with preservation of the recurrent and superior laryngeal nerves and normal vocal fold motility during the observation period. A mean decrease of the speaking fundamental frequency (SFF) of 12 Hz was found on day 4; in 8 patients the postoperative vocal pitch was more than 2 semitones lower. The distance between the highest and lowest F₀ during speaking was diminished (speech was more monotone) and the vocal jitter was elevated. In the frequency spectrum, there was a diminished prominence of the harmonics. The other spectral parameters (as the slope of the spectrum and the H1/H2 ratio) were unchanged. All changes had disappeared the fifteenth day, except for a lower SFF (>2 semitones) in 2 cases. It is concluded that after normal dissection of the laryngeal nerves, and in the absence of vocal fold paresis, other reasons for voice changes immediately after thyroidectomy remain: alterations in the neck muscles, in the laryngeal mucosa, and in the patient's general condition. Although the effects seem limited and of short duration, knowledge of them is helpful when informing the patient before thyroid surgery.     

Combination thyroplasty and the "twisted larynx:" combined type IV and type I thyroplasty for superior laryngeal nerve weakness.

Vocal cord medialization through Isshiki type I thyroplasty is part of the standard approach for patients with unilateral vocal cord immobility secondary to recurrent laryngeal nerve paralysis. However, several other modalities have been used to treat the symptomatic "twisted" larynx caused by unilateral superior laryngeal nerve weakness. The Isshiki type IV thyroplasty (cricothyroid approximation) specifically addresses cricothyroid muscle weakness, but, canine studies at the Mayo Clinic demonstrated a trend toward decreased acoustic power and sound intensity with simulated cricothyroid activity. Thus it is reasoned that addition of an ipsilateral type I thyroplasty should help compensate for this power loss. Using videostroboscopic and acoustic analysis, 9 patients with unilateral superor laryngeal nerve weakness were treated with combination type IV and type I thyroplasty. Subjective dysphonia and objective visual and acoustic measurements revealed postoperative improvement in most patients. The combination type IV and type I thyroplasty is recommended for surgical treatment of patients with superior laryngeal nerve weakness, because it addresses cricothyroid muscle weakness without compromising vocal power.     

Determining the etiology of mild vocal fold hypomobility

The prevalence of mild vocal fold hypomobility is unknown. In a study by Heman-Ackah et al, vocal fold hypomobility in a population of singing teachers was found to be associated more frequently with vocal complaints than was the presence of vocal fold masses.¹ The etiology of mild vocal fold hypomobility has not been previously explored. In the present study, a retrospective chart review was performed of 134 patients who presented to a tertiary laryngology referral center over a 6-month period for evaluation of vocal complaints. Of the 134 patients, 61 (46%) were found to have mild vocal fold hypomobility previously undiagnosed by the referring otolaryngologist. Imaging studies and laboratory tests to evaluate for structural, metabolic, and infectious causes of the decreased mobility had been ordered. Forty-nine patients completed the work-up. Of these, 41 out of 49 (84%) were found to have imaging or laboratory findings that could explain the hypomobility. Thyroid abnormalities were found to be associated with vocal fold hypomobility in 21 out of 49 (43%) of those with a complete evaluation. Other causes of vocal fold hypomobility included idiopathic (8 of 49, 16%), viral neuritis (5 of 49, 10%), central nervous system abnormality (4 of 49, 8%), neural tumor (3 of 49, 6%), joint dysfunction (3 of 49, 6%), iatrogenic nerve injury (2 of 49, 4%), myopathy (2 of 49, 4%), and noniatrogenic traumatic nerve injury (1 of 49, 2%), This study shows that unilateral vocal fold hypomobility often is associated with a physiologic process, and a complete investigation to determine the etiology is warranted in all cases.     

Arytenoid Cartilage Dislocation: A 20-year Experience

SUMMARY: Arytenoid cartilage dislocation is an infrequently diagnosed cause of vocal fold immobility. Seventy-four cases have been reported in the literature to date. Intubation is the most common origin, followed by external laryngeal trauma. Decreased volume and breathiness are the most common presenting symptoms. We report on 63 patients with arytenoid cartilage dislocation treated by the senior author (RTS) since 1983. Significantly more posterior than anterior dislocations were represented. Although reestablishing joint mobility is difficult, endoscopic reduction should be considered to align the heights of the vocal processes. This process may result in significant voice improvement even long after the dislocation. Strobovideolaryngoscopy, laryngeal electromyography, and laryngeal computed tomography (CT) imaging are helpful in the evaluation of patients with vocal fold immobility to help distinguish arytenoid cartilage dislocation from vocal fold paralysis. Familiarity with signs and symptoms of arytenoid cartilage dislocation and current treatment techniques improves the chances for optimal therapeutic results.     

Laryngeal injuries after short-versus long-term intubation

Forty-five patients were seen over a 5-year period with laryngeal injuries following endotracheal intubation (ETI). The mean duration of ETI was 5.6 days (2 hours to 37 days). Patients intubated for less than 24 hours were most likely to present with a vocal fold immobility or an anterior glottic web. Long-term intubation was associated with the development of subglottic stenoses and granulomas. Patients with vocal fold immobility were seen more often after ETI for surgical reasons and had a significantly higher incidence of previous intubation and tobacco usage. Subglottic stenoses were seen in younger patients intubated for medical reasons and associated with nasogastric tubes and longer periods of intubation.     

Endoscopic microsuture repair of vocal fold defects

The presence of a nonvibratory segment of vocal folds after microlaryngeal surgery is often a cause of poor voice result. The etiology of a nonvibratory segment is due to full thickness epithelial defect followed by secondary wound closure and scar contracture. To reduce scar contracture and nonvibratory segment of the vocal folds, primary repair with a 6-0 chromic endo-knot suture technique was used to close defects and approximate microflaps of the vocal folds. This was done in 18 patients with epithelial defects after resection of benign vocal fold lesions. The pathologic findings included severe polypoid degeneration (n = 7), fusiform laryngeal polyps (n = 5), sulcus vocalis (n = 2), cyst (n = 2), and keratosis (n = 2). Voice was improved in all patients after surgery. Comparison of vocal fold vibration before and after surgery showed improvements in configuration, amplitude, and mucosal wave. Vocal folds that were sutured all had good vibratory characteristics; none had a nonvibrating segment at the site of suture placement. Voice and healing after microsuture technique were near normal by Day 10 and return of mucosal wave was often complete by Day 14. Endoscopic microsuture closure of microflaps of the vocal folds edge is safe and affords the surgeon an opportunity for primary repair with improved functional result.     

Botulinum toxin injection in the treatment of vocal fold paralysis associated with multiple sclerosis: A case report

Botulinum toxin has been demonstrated clinically to be an effective treatment for a variety of laryngeal problems, most notably spasmodic dysphonia. As in other movement disorders, the theory behind the injection of this substance in the larynx has been a weakening of the vocal fold musculature to relieve uncoordinated and spasmodic movement of the vocal folds, presumably rebalancing the forces within the intralaryngeal musculature. Recently, this concept was applied to help reposition the arytenoid cartilage in acute and longstanding anteromedial cricoarytenoid dislocations. This same concept may apply to the paralyzed vocal fold. In support of this idea, a number of investigators have shown that immobile, clinically paralyzed vocal folds may still have partial voluntary motor unit activity. This voluntary activation may not produce clinically evident movement but may be sufficient to produce tone within the fold. If the voluntary motor units in the abductor musculature of the paralyzed fold are weakened with botulinum toxin, the continued pull of the functioning adductor musculature may be sufficient to medialize the paralyzed fold. This idea has been supported by animal experiments, which have shown that botulinum toxin may affect the ability of the fold to rebalance itself. With this evidence in mind, a patient with fold immobility secondary to multiple sclerosis was treated in an attempt at laryngeal rebalancing, using botulinum toxin to medialize the fold. However, instead of simply having the fold return fixed to the midline, the patient regained normal laryngeal mobility and voice. While it is unclear whether the botulinum toxin alone was responsible, the coincidence of this occurrence certainly requires reporting. This paper is a report of the first successful treatment of vocal fold paralysis using botulinum toxin to treat vocal fold fixation in a patient with multiple sclerosis.     

Analysis of spasmodic dysphonia by aerodynamic and laryngostroboscopic measurements

Sequential assessment of laryngeal function using laryngostroboscopy and phonatory air flow assessment was carried out in 18 patients with spasmodic dysphonia (SD). Comparison was made between findings in patients before treatment (n = 18), after unilateral recurrent nerve block by lidocaine (n = 6), after bilateral injections of botulinum toxin (Botox) (n = 13), and prior to Botox reinjection (n = 3). Unilateral nerve block resulted in higher mean phonatory airflows than after bilateral Botox injections. Both unilateral nerve block and Botox injections increased fluctuant or alternating flow source (AC); however, unilateral nerve block resulted in more unmodulated airflow leakage. Phonation time on a single breath was longer than with Botox injection. Bilateral Botox injections resulted in better glottal closure, fewer instances of vocal fold level differences, and, better vocal fold vibrations with phase symmetry, as determined by laryngostroboscopy. Partial bilateral denervation using Botox resulted in laryngeal function, which appeared to be intermediate between that of tightly squeezed pretreatment status and a breathy voice with incomplete adduction after unilateral nerve block. Of all treatments assessed, bilateral partial denervation by Botox appeared to be the most physiologic in restoring normal vocal fold vibratory function and airflow.     

Effects of vagal nerve stimulation on laryngeal function

Functional electrical stimulation is a developing methodology that shows significant potential in the management of peripheral neuromuscular deficits. Potential applications in the head and neck area, including control of bilateral vocal fold paralysis and spasmodic dysphonia, have recently been explored. Despite promising early results, very little is known about the mechanisms of action or the long-term effects of electrical stimulation on human laryngeal function. Recent development of implantable vagal nerve stimulators as a method to control intractable seizures in individuals who have not responded to medication provides a unique opportunity to study its effect on the normal human larynx. Laryngeal and vocal function testing was studied on five individuals who had undergone vagal nerve stimulator implants for intractable seizures. Consistent abduction/adduction of the left vocal fold was achieved at 20 and 40 Hz, respectively. Higher levels of electrical stimulation produced hemispasm of the larynx. Results were consistent with studies in the literature of recurrent laryngeal nerve stimulation in animal and human models. The vagus nerve provides relatively easy access for implantation of electrodes to provide electrical stimulation to the muscles of the larynx. Vagal nerve stimulation may prove efficacious in the treatment of movement disorders of the larynx; further study is needed.     

Unilateral recurrent laryngeal nerve paralysis:The importance of “preoperative” voice therapy

This preliminary retrospective study of 19 female patients and 22male patients with unilateral recurrent nerve lesions demonstrated the promise of objective measurements in predicting the need for surgery, the efficacy of voice therapy in ameliorating vocal symptoms, and the effects of therapy in conjunction with surgery. Sixty-eight percent (68%) of the female patients and 64% of the male patients did not elect to have surgery. Outcome satisfaction of nonsurgical and surgical patients appeared to be similar. The data from this study support the importance of preoperative therapy for patients with unilateral vocal fold paralysis.     

Unilateral recurrent laryngeal nerve paralysis: A re-examination

Re-examination of flexible fiberoptic videotaped laryngeal images of 39 patients with unilateral recurrent laryngeal nerve paralysis (URLNP) by four observer-judges revealed consistent findings of a unilaterally appearing shorter vocal fold with asymmetry of the arytenoid complex on the involved side. No previous similar experience in otolaryngological training or practice has been encountered. Multiple discrepancies between and among observer-judges regarding vocal fold positions during phonation were encountered. Possible explanations are discussed. The need for further investigation to determine the mechanics causing these differences is stressed. It is suggested that for the present, such terms as median, paramedian, and intermediate be used in teaching and in practice as generalities only.     

Vocal fold paralysis secondary to cardiac countershock (cardioversion)

Application of electrical energy to the heart is effective in treating many dysrhythmias. There are, however, also disadvantages associated with cardioversion. Employment of external electrical current has been shown to induce epicardial and myocardial damage at the site of electrode application. We present the only case in the English literature of vocal fold paralysis in which the single identified associated event was cardioversion. In this case of temporary vocal fold paralysis, there was no invasive procedure to directly damage the nerve. Echocardiography of the patient revealed a large left atrium, placing the recurrent laryngeal nerve in an abnormal anatomic position where it was vulnerable to the electric current.     

Vocal fold microsurgery in singers

Some singers with benign vocal fold mucosal lesions remain unacceptably impaired vocally in spite of compliance with a regimen of medical treatment and voice therapy lasting several months—or even years. I present here my experience with 62 singers who, because of this predicament, chose to undergo vocal fold microsurgery. This series is the second largest reported to date in English literature. Procedures are presented which were used for patient selection, education, and vocal retraining, as well as for surgery itself and postoperative care. Results reported here include (a) comparison of my auditory-perceptual ratings of singing voice impairment before and after surgery, (b) preoperative versus postoperative videostroboscopic findings, (c) postoperative rate of return to public singing, and (d) postoperative patient questionnaires which sought to uncover patient/singer perceptions of the results of vocal fold surgery. Excellent results were achieved overall with a very low incidence of untoward results, and no complications were encountered.     

The Evolving Etiology of Bilateral Vocal Fold Immobility

In the past, bilateral vocal fold immobility (BVFI) occurred most commonly after thyroidectomy. However, no large series documenting the etiology of adult BVFI has been published within the past fifteen years. This study reviews the etiologic patterns of BVFI at our institutions. We compare BVFI from before and after 1980. We also review combined studies of unilateral vocal fold immobility (UVFI) to compare and unilateral versus bilateral etiologic trends. In comparison with previously published series, fewer cases of BVFI present today as a complication of thyroid surgery and more as the result of malignancies and nonsurgical trauma. Unfortunately, BVFI caused by malignancy is not usually an initial sign of local disease, but an ominous sign of recurrence or metastases. In comparing UVFI and BVFI we found that thyroidectomy causes a higher percentage of BVFI than of UVFI. Over one-third of UVFI cases were caused by neoplasm which further underscores the potential seriousness of immobile vocal folds and the need for careful investigation.     

Vocal fold hemorrhage associated with coumadin therapy in an opera singer

Vocal fold hemorrhage can represent a disastrous and potentially career ending injury to a singer or professional voice user. The risk factors of vocal fold hemorrhage, including laryngeal trauma, phonotrauma, aspirin and nonsteroidal antiinflammatories, and hormonal imbalances are well known. We present a case of an opera singer who developed recurrent vocal fold hemorrhage associated with coumadin anticoagulation therapy. This case highlights the importance of the risk of vocal fold hemorrhage to professional singers and professional voice users and offers an alternative to long-term coumadin therapy in this select population.