Specific Vagus Nerve Lesion Have Distinctive Physiologic Mechanisms of Dysphagia.
Dysphagia; Animal model; Kinematics; Superior laryngeal nerve; recurrent laryngeal nerve
Swallowing is complex at anatomical, functional, and neurological levels. The connections among these levels are poorly understood, yet they underpin mechanisms of swallowing pathology. The complexity of swallowing physiology means that multiple failure points may exist that lead to the same clinical diagnosis (e.g., aspiration). The superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN) are branches of the vagus that innervate different structures involved in swallowing. Although they have distinct sensory fields, lesion of either nerve is associated clinically with increased aspiration. We tested the hypothesis that despite increased aspiration in both case, oropharyngeal kinematic changes and their relationship to aspiration would be different in RLN and SLN lesioned infant pigs. We compared movements of the tongue and epiglottis in swallows before and after either RLN or SLN lesion. We rated swallows for airway protection. Posterior tongue ratio of safe swallows changed in RLN (p = 0.01) but not SLN lesioned animals. Unsafe swallows post lesion had different posterior tongue ratios in RLN and SLN lesioned animals. Duration of epiglottal inversion shortened after lesion in SLN animals (p = 0.02) but remained unchanged in RLN animals. Thus, although SLN and RLN lesion lead to the same clinical outcome (increased aspiration), the mechanisms of failure of airway protection are different, which suggests that effective therapies may be different with each injury. Understanding the specific pathophysiology of swallowing associated with specific neural insults will help develop targeted, disease appropriate treatments.
Gould Francois D H; Lammers Andrew R; Mayerl Christopher J; German Rebecca Z
Frontiers in neurology
2019
1905-07
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Journal Article
<a href="http://doi.org/10.3389/fneur.2019.01301" target="_blank" rel="noreferrer noopener">10.3389/fneur.2019.01301</a>
The Physiologic Impact of Unilateral Recurrent Laryngeal Nerve (RLN) Lesion on Infant Oropharyngeal and Esophageal Performance.
Animal; Animals; Aspiration; Biological; Deglutition; Deglutition – Physiology; Deglutition disorders; Deglutition Disorders – Etiology; Deglutition Disorders – Physiopathology; Deglutition Disorders/*etiology/physiopathology; Deglutition/*physiology; Disease Models; Esophagus; Esophagus – Physiopathology; Esophagus/*physiopathology; Human; Infant; Laryngeal Nerves – Injuries; Laryngeal Nerves – Physiopathology; Models; Oropharynx – Physiopathology; Oropharynx/*physiopathology; Recurrent laryngeal nerve; Recurrent Laryngeal Nerve Injuries/*complications/physiopathology; Recurrent Laryngeal Nerve/*physiopathology; Swine
Recurrent laryngeal nerve (RLN) injury in neonates, a complication of patent ductus arteriosus corrective surgery, leads to aspiration and swallowing complications. Severity of symptoms and prognosis for recovery are variable. We transected the RLN unilaterally in an infant mammalian animal model to characterize the degree and variability of dysphagia in a controlled experimental setting. We tested the hypotheses that (1) both airway protection and esophageal function would be compromised by lesion, (2) given our design, variability between multiple post-lesion trials would be minimal, and (3) variability among individuals would be minimal. Individuals' swallowing performance was assessed pre- and post-lesion using high speed VFSS. Aspiration was assessed using the Infant Mammalian Penetration-Aspiration Scale (IMPAS). Esophageal function was assessed using two measures devised for this study. Our results indicate that RLN lesion leads to increased frequency of aspiration, and increased esophageal dysfunction, with significant variation in these basic patterns at all levels. On average, aspiration worsened with time post-lesion. Within a single feeding sequence, the distribution of unsafe swallows varied. Individuals changed post-lesion either by increasing average IMPAS score, or by increasing variation in IMPAS score. Unilateral RLN transection resulted in dysphagia with both compromised airway protection and esophageal function. Despite consistent, experimentally controlled injury, significant variation in response to lesion remained. Aspiration following RLN lesion was due to more than unilateral vocal fold paralysis. We suggest that neurological variation underlies this pattern.
Gould Francois D H; Lammers Andrew R; Ohlemacher Jocelyn; Ballester Ashley; Fraley Luke; Gross Andrew; German Rebecca Z
Dysphagia
2015
2015-12
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1007/s00455-015-9648-8" target="_blank" rel="noreferrer noopener">10.1007/s00455-015-9648-8</a>