A computational study of the role of the aortic arch in idiopathic unilateral vocal-fold paralysis

Computed Tomography Measurements in Assessment of Idiopathic Vocal Fold Paralysis

OBJECTIVE

Our study aimed to both identify the incidence and clinical presentation of patients presenting with idiopathic vocal fold paralysis (IVFP). Secondarily we aimed to assess the radiographic findings of computed tomography (CT) studies along the course of the vagus and recurrent laryngeal nerves (RLN), specifically measuring for potential areas of compression at the skull base and mediastinum. We hypothesized that a proportion of patients diagnosed with IVFP would have significant differences in measurements when compared to age-gender matched controls on CT imaging.

STUDY DESIGN

Institutional review board approved retrospective cohort study METHODS: We assessed patients presenting to a tertiary voice care center between 2003 and 2019 with diagnosis of vocal fold paralysis. Data collected includes demographics, clinical exam findings, and CT measurements including dimensions at bilateral jugular foramen, aortopulmonary (AP) window and surrounding vascular structures. Statistical analysis was then performed using Pearson χ², and Mann Whitney U tests to determine differences variables of interest.

RESULTS

A total of 606 patients were reviewed. Of these patients 60 (9.9%) patients were determined to have IVFP. Left-sided VFP was seen more commonly in 78.3% (N = 47) of idiopathic patients. Our IVFP group had an overall higher incidence of cardiovascular disease [OR = 3.378, 95%CI 1.907-5.941, P < 0.001] compared to those with identified causes for paralysis. Specifically, IVFP patients showed a higher incidence of combined cardiovascular co-morbidities (P < 0.001), mitral valve stenosis (P = 0.007), pulmonary hypertension (P < 0.0001) and congestive heart failure (P < 0.001). When evaluating CT imaging, the AP window was mentioned in only 2 (3.3%) of our idiopathic patients CT reports. The IVFP cohort had a lower median AP window volume (P = 0.020) when compared to age-gender matched controls. This significantly smaller AP window volume was also seen when only left sided IVFP compared to both right-sided paralysis (P < 0.001) and age matched control patients (P < 0.001).

CONCLUSION

The significance of cardiovascular comorbidities combined with findings of statistically narrowed AP window may help provide an explanation of a subset of patients diagnosed with IVFP.

The Causes and Laryngeal Electromyography Characteristics of Unilateral Vocal Fold Paralysis

OBJECTIVE

To investigate the causes and laryngeal electromyography (LEMG) characteristics of unilateral vocal fold paralysis (UVFP).

METHODS

We retrospectively analyzed the history and LEMG of 337 patients with unilateral vocal fold immobility. The etiology was reviewed and the characteristics of LEMG (including spontaneous potential, recruitment potential, evoked potential, synkinesia, and et al.) were analyzed.

RESULTS

The causes included injury (177 cases, 52.5%), idiopathic causes (72 cases, 21.4%), infection (61 cases, 18.1%), tumor and compressive factors (27 cases, 8.0%). Among the injury group, 161 cases were caused by surgery (111 cases of thyroid surgery), and 16 cases were caused by trauma. LEMG showed that complete nerve injury was present in 72.9% of the injury group, 66.7% of the tumors or compressive factors group, 49.2% of the infection group, and 44.4% of the idiopathic group. Of the 337 patients, 136 patients (40.4%) had synkinesia in the posterior cricoarytenoid muscles, and only two of these patients also had synkinesia in the thyroarytenoid muscles. The proportion of complete recurrent laryngeal nerve (RLN) injury in patients with synkinesia was higher than that of patients without synkinesia.

CONCLUSION

The main cause of vocal fold paralysis is neck surgery, most commonly thyroid surgery. Patients with different causes of paralysis had different severities of RLN injury. LEMG showed that surgery or trauma accounted for the highest proportion of complete nerve injury. Patients with severe RLN injury were more prone to synkinesia, and the posterior cricoarytenoid muscles were more likely to have synkinesia than the thyroarytenoid muscles.

Laryngeal adductor function following potassium titanyl phosphate laser welding of the recurrent laryngeal nerve

OBJECTIVES/HYPOTHESIS

Recurrent laryngeal nerve (RLN) transection injuries may occur during thyroidectomy and other surgical procedures. Laser nerve welding has been shown to cause less technique-related axonal damage than the traditional suture method. We compared functional adductor results using these two methods of RLN repair.

STUDY DESIGN

Animal model.

METHODS

Canine hemilarynges underwent pretreatment testing of laryngeal adductor function, followed by RLN transection and repair using potassium titanyl phosphate (KTP) laser welding (n = 8) or microneural suture (n = 16) techniques. Six months later, adductor function was measured again and expressed as a proportion of the pretreatment value.

RESULTS

The mean laryngeal adductor pressure ratios were 82.4% (95% confidence interval [CI]: 72.8%-92.0%) for the laser repair group and 55.5% (95% CI: 49.4%-61.6%) for the suture control group, with a difference of 26.9% (95% CI: 15.3%-38.5%). Both spontaneous and stimulated glottic closure was observed in the laser welding and microsuture repair groups.

CONCLUSIONS

Laser nerve welding resulted in greater strength of adduction than suture repair of an acutely transected RLN. Suture anastomosis may traumatize more axons than the laser. Stronger vocal fold adduction is associated clinically with better protection from aspiration and improved voice outcomes. KTP laser welding should be considered for anastomosis of the RLN and other nerves.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:1764-1769, 2020.

Idiopathic Unilateral Vocal Fold Paralysis in Older Patients: Characteristics in the Disease Course and Implication of Computed Tomography for Evaluation of Etiology

OBJECTIVES

This study aimed to compare the characteristics of idiopathic unilateral vocal fold paralysis (IUVFP) in elderly versus younger patients, including the diagnostic yield of computed tomography (CT) scans for identifying the structural causes of IUVFP.

METHODS

We retrospectively analyzed medical records of the patients initially diagnosed with IUVFP in a single referral tertiary hospital. We compared patients' baseline characteristics, initial symptoms, laryngoscopic findings, and prevalence of structural causes on CT scans with respect to age (younger, <65 years vs older, ⩾65 years).

RESULTS

One hundred forty-two patients were enrolled (90 younger, 52 older). Evident structural causes were more frequently found on CT in older patients than younger patients (40.4% vs 22.2%, P = .034). Among truly idiopathic cases (70 younger, 31 older), recovered vocal fold mobility was identified in 48.6% younger and 41.9% older patients ( P = .666). There was no statistically significant difference in the characteristics between unrecovered and recovered subjects of the older patients with true IUVFP (all P > .05).

CONCLUSIONS

The CT scans provided significantly higher diagnostic yields in older patients than younger patients. The degrees of symptoms and complications and likelihood of natural recovery did not significantly differ between younger and older patients with IUVFP.

Association between Upper Respiratory Infection and Idiopathic Unilateral Vocal Fold Paralysis

INTRODUCTION

Unilateral vocal fold paralysis (UVFP) without an identifiable cause is termed idiopathic unilateral vocal fold paralysis (IUVFP). Some authors have postulated that select cases of IUVFP have a viral etiology, but the causality has not been established. We set out to review institutional cases of IUVFP and determine if there is a correlation between upper respiratory infection symptoms and presentation of IUVFP.

METHODS

Cases of IUVFP were reviewed over a 10-year period (2002-2012). The history was investigated to review presenting symptoms. We specifically reviewed for symptoms of upper respiratory infection at the onset of UVFP and tallied the frequency. Symptoms included sore throat, laryngitis, cough, influenza, bronchitis, pneumonia, otalgia, and sinusitis. The seasonal onset (if possible) was determined based on the history provided from the initial consultation.

STUDY DESIGN

Case series.

RESULTS

Overall, 107 patients presented with IUVFP; 35.5% of patients reported symptoms of upper respiratory infection at the onset of UVFP. Among these individuals, pharyngitis/laryngitis was the most common presenting symptom; 34.2% reported cough. In total, 40.0% of patients with IUVFP reported an onset of symptoms between December and February.

CONCLUSIONS

This study suggests that symptoms of upper respiratory infection frequently occur with the presentation of IUVFP. The onset of symptoms tended to occur between December and February. The mechanism of viral-mediated UVFP has not been established. Future studies to explore this pathophysiology are needed.

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.