Clarifying optimal outcome measures in intermittent and continuous laryngeal neuromonitoring.

BACKGROUND: Intraoperative neuromonitoring (IONM) techniques have evolved over the past decade into intermittent IONM (I-IONM) and continuous IONM (C-IONM) modes of application. Despite many prior publications on both types of IONM, there remains uncertainty about what outcomes should be measured for each form of IONM. The primary objective of this paper is to define categories of benefit for I-IONM/C-IONM and to clarify and standardize their reporting outcomes. METHODS: Expert review consensus statement utilizing modified Delphi methodology. RESULTS: I-IONM provides diagnosis, classification, and prevention of nerve injury through accurate and early nerve identification. C-IONM provides real-time information on nerve functional integrity and thus may prevent some types of nerve injury but cannot assist in nerve localization. Sudden mechanisms of nerve injury cannot be predicted or prevented by either technique. CONCLUSIONS: I-IONM and C-IONM are complementary techniques. Future studies evaluating the utility of IONM should focus on outcomes that are appropriate to the type of IONM being utilized.

Immediate and partial neural dysfunction after thyroid and parathyroid surgery: Need for recognition, laryngeal exam, and early treatment.

BACKGROUND: Laryngeal dysfunction after thyroid and parathyroid surgery requires early recognition and a standardized approach for patients that present with voice, swallowing, and breathing issues. The Endocrine Committee of the American Head and Neck Society (AHNS) convened a panel to define the terms "immediate vocal fold paralysis" and "partial neural dysfunction" and to provide clinical consensus statements based on review of the literature, integrated with expert opinion of the group. METHODS: A multidisciplinary expert panel constructed the manuscript and recommendations for laryngeal dysfunction after thyroid and parathyroid surgery. A meta-analysis was performed using the literature and published guidelines. Consensus was achieved using polling and a modified Delphi approach. RESULTS: Twenty-two panelists achieved consensus on five statements regarding the role of early identification and standardization of evaluation for patients with "immediate vocal fold paralysis" and "partial neural dysfunction" after thyroid and parathyroid surgery. CONCLUSION: After endorsement by the AHNS Endocrine Section and Quality of Care Committee, it received final approval from the AHNS Council.

International neuromonitoring study group guidelines 2018: Part II: Optimal recurrent laryngeal nerve management for invasive thyroid cancer-incorporation of surgical, laryngeal, and neural electrophysiologic data.

The purpose of this publication was to inform surgeons as to the modern state-of-the-art evidence-based guidelines for management of the recurrent laryngeal nerve invaded by malignancy through blending the domains of 1) surgical intraoperative information, 2) preoperative glottic function, and 3) intraoperative real-time electrophysiologic information. These guidelines generated by the International Neural Monitoring Study Group (INMSG) are envisioned to assist the clinical decision-making process involved in recurrent laryngeal nerve management during thyroid surgery by incorporating the important information domains of not only gross surgical findings but also intraoperative recurrent laryngeal nerve functional status and preoperative laryngoscopy findings. These guidelines are presented mainly through algorithmic workflow diagrams for convenience and the ease of application. These guidelines are published in conjunction with the INMSG Guidelines Part I: Staging Bilateral Thyroid Surgery With Monitoring Loss of Signal. Level of Evidence: 5 Laryngoscope, 128:S18-S27, 2018.

International neural monitoring study group guideline 2018 part I: Staging bilateral thyroid surgery with monitoring loss of signal.

This publication offers modern, state-of-the-art International Neural Monitoring Study Group (INMSG) guidelines based on a detailed review of the recent monitoring literature. The guidelines outline evidence-based definitions of adverse electrophysiologic events, especially loss of signal, and their incorporation in surgical strategy. These recommendations are designed to reduce technique variations, enhance the quality of neural monitoring, and assist surgeons in the clinical decision-making process involved in surgical management of recurrent laryngeal nerve. The guidelines are published in conjunction with the INMSG Guidelines Part II, Optimal Recurrent Laryngeal Nerve Management for Invasive Thyroid Cancer-Incorporation of Surgical, Laryngeal, and Neural Electrophysiologic Data. Laryngoscope, 128:S1-S17, 2018.

Otolaryngology in Low-Resource Settings: Practical and Ethical Considerations.

Providing otolaryngology care in low-resource settings requires careful preparation to ensure good outcomes. The level of care that can be provided is dictated by available resources and the supplementary equipment, supplies, and personnel brought in. Other challenges include personal health and safety risks as well as cultural and language differences. Studying outcomes will inform future missions. Educating and developing ongoing partnerships with local physicians can lead to sustained improvements in the local health care system.

Indications for Surgical Repair of Type 1 Laryngeal Cleft.

OBJECTIVES: Type 1 laryngeal cleft (T1LC) is a congenital deficiency in the posterior glottis, resulting in a communication between the hypopharynx and glottis. No consensus treatment paradigm exists for timing and criteria for patient selection for surgical repair. Our goal is to assess whether patient characteristics can help predict improvement after surgery. METHODS: After Institutional Review Board exemption, a retrospective chart review was performed for patients undergoing surgery to diagnose a T1LC. Charts were examined for age, presenting symptoms, comorbidities, pre/postoperative videoflouroscopic swallow study reports, and outcomes. RESULTS: Ninety-seven patients with clinical suspicion for T1LC underwent direct laryngoscopy and bronchoscopy, and 63 (64%) were diagnosed with a T1LC. Twenty-two patients (63%) undergoing surgery achieved clinical or radiographic improvement. There was no difference in average age, aspiration, or penetration between clinical improvement and no improvement groups. Of 13 patients with comorbidities that increase their risk of aspiration, 12 were significantly improved. There were 5 complications, which were managed conservatively. CONCLUSIONS: Our experience supports the repair of T1LC repair at time of diagnostic laryngoscopy if satisfactory improvement is not noted with conservative treatment. This should be performed without segregation for age, comorbidities, or degree of dysphagia. Our technique is performed with minimal complications and achieves satisfactory results.

Aortic arch compliance and idiopathic unilateral vocal fold paralysis.

Unilateral vocal fold paralysis (UVP) occurs related to recurrent laryngeal nerve (RLN) impairment associated with impaired swallowing, voice production, and breathing functions. The majority of UVP cases occur subsequent to surgical intervention with approximately 12-42% having no known cause for the disease (i.e., idiopathic). Approximately two-thirds of those with UVP exhibit left-sided injury with the average onset at ≥50 yr of age in those diagnosed as idiopathic. Given the association between the RLN and the subclavian and aortic arch vessels, we hypothesized that changes in vascular tissues would result in increased aortic compliance in patients with idiopathic left-sided UVP compared with those without UVP. Gated MRI data enabled aortic arch diameter measures normalized to blood pressure across the cardiac cycles to derive aortic arch compliance. Compliance was compared between individuals with left-sided idiopathic UVP and age- and sex-matched normal controls. Three-way factorial ANOVA test showed that aortic arch compliance (P = 0.02) and aortic arch diameter change in one cardiac cycle (P = 0.04) are significantly higher in patients with idiopathic left-sided UVP compared with the controls. As previously demonstrated by other literature, our finding confirmed that compliance decreases with age (P < 0.0001) in both healthy individuals and patients with idiopathic UVP. Future studies will investigate parameters of aortic compliance change as a potential contributor to the onset of left-sided UVP.NEW & NOTEWORTHY Unilateral vocal fold paralysis results from impaired function of the recurrent laryngeal nerve (RLN) impacting breathing, swallowing, and voice production. A large proportion of adults suffering from this disorder have an idiopathic etiology (i.e., unknown cause). The current study determined that individuals diagnosed with left-sided idiopathic vocal fold paralysis exhibited significantly greater compliance than age- and sex-matched controls. These seminal findings suggest a link between aortic arch compliance levels and RLN function.

Laryngeal examination in thyroid and parathyroid surgery: An American Head and Neck Society consensus statement: AHNS Consensus Statement.

This American Head and Neck Society (AHNS) consensus statement discusses the techniques of laryngeal examination for patients undergoing thyroidectomy and parathyroidectomy. It is intended to help guide all clinicians who diagnose or manage adult patients with thyroid disease for whom surgery is indicated, contemplated, or has been performed. This consensus statement concludes that flexible transnasal laryngoscopy is the optimal laryngeal examination technique, with other techniques including laryngeal ultrasound and stroboscopy being useful in selected scenarios. © 2016 Wiley Periodicals, Inc. Head Neck 38: 811-819, 2016.

Thyroidectomy in the professional singer-neural monitored surgical outcomes.

BACKGROUND: Voice changes commonly occur from thyroidectomy and may be due to neural or nonneural causes. Such changes can be a source of significant morbidity for any patient, but thyroidectomy in the professional singer carries special significance. We test the hypothesis that the career of singers and professional voice users is not impaired after neural monitored thyroid surgery. METHODS: A quantitative analysis of pre- and postoperative neural monitored thyroid surgery voice outcomes utilizing three validated vocal instruments-Voice Handicap Index (VHI), Singing Voice Handicap Index (SVHI), and Evaluation of Ability to Sing Easily (EASE)-in a unique series of professional singers/voice users was performed. Additional quantitative analysis related to final intraoperative electromyography (EMG) amplitude, the time to return to performance, and vocal parameters affected during this interval was performed. RESULTS: Twenty-seven vocal professionals undergoing thyroidectomy were identified, of whom 60% had surgery for thyroid cancer. Pre- and postsurgery flexible fiberoptic laryngeal exams were normal in all patients. Return to performance rate was 100%, and mean time to performance was 2.26 months (±1.61). All three vocal instrument mean scores, pre-op vs. post-op, were unchanged: VHI, 4.15 (±5.22) vs. 4.04 (±3.85), p=0.9301; SVHI, 11.26 (±14.41) vs.12.07 (±13.09), p=0.8297; and EASE, 6.19 (±9.19) vs. 6.00 (±7.72), p=0.9348. The vocal parameters most affected from surgery until first performances were vocal fatigue (89%), high range (89%), pitch control and modulation (74%), and strength (81%). Final mean intraoperative EMG amplitude was within normal limits for intraoperative stimulation and had no relationship with time to first professional performance (p=0.7199). CONCLUSIONS: Neural monitored thyroidectomy, including for thyroid malignancy, in professional voice users is safe without any changes in three different voice/singing instruments, with 100% return to performance. Intraoperative EMG data at the conclusion of surgery and postoperative laryngeal exam were normal in all patients. Specific vocal parameters are transiently affected during the postoperative recovery phase, which is important to outline in the consent process of this unique patient population and may provide insight into the physiologic state of the larynx subsequent to thyroid surgery.

External branch of the superior laryngeal nerve monitoring during thyroid and parathyroid surgery: International Neural Monitoring Study Group standards guideline statement.

UNLABELLED: Intraoperative neural monitoring (IONM) during thyroid surgery has gained widespread acceptance as an adjunct to the gold standard of visual identification of the recurrent laryngeal nerve (RLN). Contrary to routine dissection of the RLN, most surgeons tend to avoid rather than routinely expose and identify the external branch of the superior laryngeal nerve (EBSLN) during thyroidectomy or parathyroidectomy. IONM has the potential to be utilized for identification of the EBSLN and functional assessment of its integrity; therefore, IONM might contribute to voice preservation following thyroidectomy or parathyroidectomy. We reviewed the literature and the cumulative experience of the multidisciplinary International Neural Monitoring Study Group (INMSG) with IONM of the EBSLN. A systematic search of the MEDLINE database (from 1950 to the present) with predefined search terms (EBSLN, superior laryngeal nerve, stimulation, neuromonitoring, identification) was undertaken and supplemented by personal communication between members of the INMSG to identify relevant publications in the field. The hypothesis explored in this review is that the use of a standardized approach to the functional preservation of the EBSLN can be facilitated by application of IONM resulting in improved preservation of voice following thyroidectomy or parathyroidectomy. These guidelines are intended to improve the practice of neural monitoring of the EBSLN during thyroidectomy or parathyroidectomy and to optimize clinical utility of this technique based on available evidence and consensus of experts. LEVEL OF EVIDENCE: 5

Airway obstruction due to unilateral vocal fold paralysis.

OBJECTIVES/HYPOTHESIS: Airway obstruction is an uncommon presentation of unilateral laryngeal paralysis. We have observed two mechanisms of obstruction: arytenoid prolapse and inappropriate adduction of the paralyzed vocal fold. We evaluated arytenoid abduction (AAb) and recurrent laryngeal nerve (RLN) reinnervation as treatments for airway obstruction in patients with unilateral laryngeal paralysis. STUDY DESIGN: Retrospective case series. METHODS: Seven patients with airway obstruction secondary to unilateral laryngeal paralysis were evaluated with flexible laryngoscopy and direct laryngoscopy. Patients with flaccid paralysis and a prolapsing arytenoid were treated with AAb. Airway obstruction due to inspiratory vocal fold adduction was managed by RLN transection and ansa reinnervation of the distal stump. RESULTS: In all cases, paralysis resulted from RLN injury during surgery: thyroidectomy or cervical spine surgery. AAb was performed in four patients with arytenoid prolapse, and all had significant airway improvement, including decannulation of the two patients who had been tracheotomy dependent. RLN reinnervation was performed in five patients, two of whom had inappropriate adduction detected after AAb. The site of RLN injury was identified at surgery in all four patients. Inspiratory stridor and laryngospasm were abolished immediately after RLN transection. CONCLUSIONS: Arytenoid prolapse and/or inappropriate laryngeal adduction can cause airway obstruction in patients with unilateral laryngeal paralysis. Treatment of airway obstruction should address the underlying pathophysiology. AAb and RLN transection with ansa reinnervation can be effective in selected patients.

Perceptual structure of adductor spasmodic dysphonia and its acoustic correlates.

OBJECTIVES: To examine the perceptual structure of voice attributes in adductor spasmodic dysphonia (ADSD) before and after botulinum toxin treatment and identify acoustic correlates of underlying perceptual factors. Reliability of perceptual judgments is considered in detail. STUDY DESIGN: Pre- and posttreatment trial with comparison to healthy controls, using single-blind randomized listener judgments of voice qualities, as well as retrospective comparison with acoustic measurements. METHODS: Oral readings were recorded from 42 ADSD speakers before and after treatment as well as from their age- and sex-matched controls. Experienced judges listened to speech samples and rated attributes of overall voice quality, breathiness, roughness, and brokenness, using computer-implemented visual analog scaling. Data were adjusted for regression to the mean and submitted to principal components factor analysis. Acoustic waveforms, extracted from the reading samples, were analyzed and measurements correlated with perceptual factor scores. RESULTS: Four reliable perceptual variables of ADSD voice were effectively reduced to two underlying factors that corresponded to hyperadduction, most strongly associated with roughness, and hypoadduction, most strongly associated with breathiness. After treatment, the hyperadduction factor improved, whereas the hypoadduction factor worsened. Statistically significant (P<0.01) correlations were observed between perceived roughness and four acoustic measures, whereas breathiness correlated with aperiodicity and cepstral peak prominence (CPPs). CONCLUSIONS: This study supported a two-factor model of ADSD, suggesting perceptual characterization by both hyperadduction and hypoadduction before and after treatment. Responses of the factors to treatment were consistent with previous research. Correlations among perceptual and acoustic variables suggested that multiple acoustic features contributed to the overall impression of roughness. Although CPPs appears to be a partial correlate of perceived breathiness, a physical basis of this percept remained less clear.

Developing a porcine model for study of vocal fold scar.

The porcine larynx is very similar in size and structure to that of humans, and wound healing in pigs is very similar to that of humans. However, the pig is not often used in vocal fold scar research because it is difficult to view the vocal folds endoscopically. To further assess the pig as a model for studying vocal scar, we compared the plane of surgical dissection in the mucosa of four porcine vocal folds with that in eight human cadaver larynges. The plane of dissection was quite similar in porcine and human larynges, occurring within the loose layer of the superficial lamina propria. We also compared healing of porcine vocal folds after elevation and replacement of an epithelial flap versus excision of epithelium, leaving an open wound. After 6 weeks, larynges were harvested for histologic examination. There was no significant difference between the mucosa of the normal vocal fold and that of the healed microflap. However, after healing of epithelial excision, there was a depressed scar, with average lamina propria thickness of 302 µm versus 864 µm for the normal fold (P<0.05). Finally, to document that the mucosal wave can be evaluated in the porcine larynx, we developed a preparation that removes the false vocal folds, to allow ex vivo phonation. Experimentally created scar in the porcine larynx is a favorable model for the study of vocal fold healing and for assessment of treatments for vocal fold scar.

Arytenoid abduction for bilateral vocal fold immobility.

PURPOSE OF REVIEW: The pathophysiology of bilateral vocal fold immobility includes two broad categories: mechanical fixation and neurogenic paralysis. A mobile arytenoid can be surgically abducted, and this procedure has been reported as a treatment for patients with bilateral neurogenic laryngeal paralysis. This article reviews the theoretical basis and clinical outcomes of this procedure. RECENT FINDINGS: Two concepts form the theoretical basis for arytenoid abduction. First, in most cases of neurogenic paralysis, laryngeal muscles are not denervated; there is considerable residual or regenerated function of adductor muscles. The vocal fold lies near the midline, because there is inadequate force to abduct the vocal fold. Second, the cricoarytenoid joint is multiaxial. The posterior cricoarytenoid (PCA) muscle rotates the arytenoid about an oblique axis to pull the vocal process laterally and superiorly, while the axis of adduction is nearly vertical. Thus, surgical abduction of the arytenoid, by simulating contraction of the PCA muscle, should not preclude active adduction during phonation or swallow. Surgical arytenoid abduction has been reported to improve the airway in many patients with bilateral laryngeal paralysis, with little or no impairment of vocal function. It is less successful in patients with inspiratory adductor muscle activity, long-term immobility, or previous procedures to statically enlarge the glottis. SUMMARY: Arytenoid abduction is a promising treatment for selected patients with bilateral neurogenic laryngeal paralysis.

Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and parathyroid surgery: international standards guideline statement.

Intraoperative neural monitoring (IONM) during thyroid and parathyroid surgery has gained widespread acceptance as an adjunct to the gold standard of visual nerve identification. Despite the increasing use of IONM, review of the literature and clinical experience confirms there is little uniformity in application of and results from nerve monitoring across different centers. We provide a review of the literature and cumulative experience of the multidisciplinary International Neural Monitoring Study Group with IONM spanning nearly 15 years. The study group focused its initial work on formulation of standards in IONM as it relates to important areas: 1) standards of equipment setup/endotracheal tube placement and 2) standards of loss of signal evaluation/intraoperative problem-solving algorithm. The use of standardized methods and reporting will provide greater uniformity in application of IONM. In addition, this report clarifies the limitations of IONM and helps identify areas where additional research is necessary. This guideline is, at its forefront, quality driven; it is intended to improve the quality of neural monitoring, to translate the best available evidence into clinical practice to promote best practices. We hope this work will minimize inappropriate variations in monitoring rather than to dictate practice options.

Arytenoid abduction: indications and limitations.

OBJECTIVES: I report further experience with arytenoid abduction (AAb), a procedure that enlarges the glottis by external rotation of the arytenoid cartilage and thus moves the vocal process laterally and rostrally, but does not preclude adduction for phonation. Therefore, AAb has the potential to preserve voice in patients with bilateral abductor laryngeal paralysis. METHODS: I performed a retrospective review of AAb in 11 patients with bilateral laryngeal paralysis and 3 patients with other neurologic causes of glottal airway compromise, ie, adductor breathing dystonia, frequent laryngospasm, and progressive laryngeal breathing dysfunction. RESULTS: Seven of the 11 patients with bilateral paralysis had dramatic airway improvement. One patient required a tracheotomy after AAb, and 3 patients with an existing tracheotomy could not be decannulated. Arytenoid abduction relieved airway obstruction in the patient with recurrent laryngospasm and in the child with progressive laryngeal breathing dysfunction, but the patient with adductor breathing dystonia has persistent stridor. The factors associated with a poor airway outcome included prolonged tracheotomy, electromyographic evidence of inspiratory activity of adductor muscles, chronic obstructive pulmonary disease, sleep apnea, and prior cordotomy or arytenoidectomy. CONCLUSIONS: Arytenoid abduction is most effective in patients with bilateral laryngeal paralysis of less than 1 year's duration who do not have unfavorable laryngeal adductor activity.

Neurotrophin expression of laryngeal muscles in response to recurrent laryngeal nerve transection.

OBJECTIVE/HYPOTHESIS: The recurrent laryngeal nerve (RLN) commonly regenerates after injury; however, functional motion is rarely recovered. Animal experiments have documented aberrant reinnervation after nerve transection, with motor axons reaching inappropriate muscles. More recently, experimental results suggest that lack of vocal fold motion after RLN injury is due to preferential reinnervation of adductor muscles, with inadequate reinnervation of the posterior cricoarytenoid muscle (PCA), the only abductor muscle of the larynx. Information on factors that could influence the receptiveness of these muscles to reinnervation could be useful in developing new therapeutic strategies. It is hypothesized that the thyroarytenoid muscle (TA) and the PCA differ in expression of neurotrophins in response to denervation. STUDY DESIGN: Laboratory experiment. METHODS: Rats were sacrificed at 3 days, 6 weeks, or 4 months after unilateral RLN injury measure expression of brain-derived nerve growth factor (BDNF), nerve growth factor (NGF), and neurotrophin 4 (NT-4) in the TA and PCA muscles, using immunohistochemistry. We also assessed nerve regeneration. RESULTS: NGF was significantly diminished in the denervated TA muscle at 3 days after injury and increased at 6 weeks. BDNF expression was unchanged in the TA, but was diminished in both PCA muscles at 3 days and 6 weeks, returning to near-normal levels at 4 months after injury. Robust nerve regeneration of distal RLN was present at 4 months. CONCLUSIONS: Results suggest that the TA and PCA muscles respond differently to denervation.

Proton pump inhibitor suppression of calcium absorption presenting as respiratory distress in a patient with bilateral laryngeal paralysis and hypocalcemia.

We report an unusual case of hypocalcemia and respiratory distress related to acid-suppressive therapy. The patient was a 50-year-old woman with bilateral laryngeal paralysis and hypoparythyroidism resulting from a thyroidectomy performed more than 30 years previously. She required large doses of calcium supplementation to maintain a normal calcium level. Her airway had been marginally adequate. A few weeks prior to presentation, she began to experience increasing dyspnea. Examination was suggestive of laryngopharyngeal reflux, and she was started on a therapeutic trial of esomeprazole 40 mg twice daily. Three days later, she presented to the emergency room with airway distress. Laboratory studies indicated that the patient had hypocalcemia. The esomeprazole was discontinued, and she was treated with intravenous calcium; her symptoms resolved. We attribute the airway distress to tetany in synkinetically reinnervated laryngeal adductor muscles. We recommend that acid-suppressive therapy should be used with caution in patients with hypoparathyroidism or hypocalcemia.

Recommendations of the Neurolaryngology Study Group on laryngeal electromyography.

The Neurolaryngology Study Group convened a multidisciplinary panel of experts in neuromuscular physiology, electromyography, physical medicine and rehabilitation, neurology, and laryngology to meet with interested members from the American Academy of Otolaryngology Head and Neck Surgery, the Neurolaryngology Subcommittee and the Neurolaryngology Study Group to address the use of laryngeal electromyography (LEMG) for electrodiagnosis of laryngeal disorders. The panel addressed the use of LEMG for: 1) diagnosis of vocal fold paresis, 2) best practice application of equipment and techniques for LEMG, 3) estimation of time of injury and prediction of recovery of neural injuries, 4) diagnosis of neuromuscular diseases of the laryngeal muscles, and, 5) differentiation between central nervous system and behaviorally based laryngeal disorders. The panel also addressed establishing standardized techniques and methods for future assessment of LEMG sensitivity, specificity and reliability for identification, assessment and prognosis of neurolaryngeal disorders. Previously an evidence-based review of the clinical utility of LEMG published in 2004 only found evidence supported that LEMG was possibly useful for guiding injections of botulinum toxin into the laryngeal muscles. An updated traditional/narrative literature review and expert opinions were used to direct discussion and format conclusions. In current clinical practice, LEMG is a qualitative and not a quantitative examination. Specific recommendations were made to standardize electrode types, muscles to be sampled, sampling techniques, and reporting requirements. Prospective studies are needed to determine the clinical utility of LEMG. Use of the standardized methods and reporting will support future studies correlating electro-diagnostic findings with voice and upper airway function.