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

Abstract

Unilateral vocal-fold paralysis (UVP) occurs when one of the vocal folds becomes paralyzed due to damage to the recurrent laryngeal nerve (RLN). Individuals with UVP experience problems with speaking, swallowing, and breathing. Nearly two-thirds of all cases of UVP is associated with impaired function of the left RLN, which branches from the vagus nerve within the thoracic cavity and loops around the aorta before ascending to the larynx within the neck. We hypothesize that this path predisposes the left RLN to a supraphysiological, biomechanical environment, contributing to onset of UVP. Specifically, this research focuses on the identification of the contribution of the aorta to onset of left-sided UVP. Important to this goal is determining the relative influence of the material properties of the RLN and the aorta in controlling the biomechanical environment of the RLN. Finite element analysis was used to estimate the stress and strain imposed on the left RLN as a function of the material properties and loading conditions. The peak stress and strain in the RLN were quantified as a function of RLN and aortic material properties and aortic blood pressure using Spearman rank correlation coefficients. The material properties of the aortic arch showed the strongest correlation with peak stress [ρ = -0.63, 95% confidence interval (CI), -1.00 to -0.25] and strain (ρ = -0.62, 95% CI, -0.99 to -0.24) in the RLN. Our results suggest an important role for the aorta in controlling the biomechanical environment of the RLN and potentially in the onset of left-sided UVP that is idiopathic.

Disease Characteristics and Electromyographic Findings of Nonsurgery-Related Unilateral Vocal Fold Paralysis

“…Indeed, idiopathic UVFP is a cluster of diagnoses when known etiologies are not yet found, given that diagnostic tools such as image studies and laboratory examinations have been performed. For hypothesis 1, additional span of the left RLN, which travels lower and around the aortic arch, might make it more susceptible to entrapment neuropathy or other local lesions Possible causes underlying this could include fibrosis, mass lesions, inflammation, or infection . For hypothesis 2, one possible cause for this is neuritis occurring in the proximal part of the laryngeal nerve .…”

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

“…A major motivation of this study was to assess the rate of dehiscence following laser repair of a larger caliber and lengthier nerve. In the canine, the RLN follows a long, indirect pathway from the brain to the larynx that is similar to the human RLN, and is likely under similar physiologic stresses . In this study, there were no cases of nerve dehiscence at 6 months.…”

A rare cause for aphonia - Ortners syndrome

“…4 The compression of the nerve and subsequent palsy is now said to occur between the aorta and pulmonary artery with the aorta playing an important role in the biomechanical environment of the RLN. 5,6 The onset of hoarseness is usually insidious, may be intermittent and in due course of time may progress to complete aphonia. LRLNP is more common than the right RLN palsy and causes the left vocal cord to be in the paramedian position.…”