AUTHOR=Gould François D. H. , Lammers Andrew R. , Mayerl Christopher J. , German Rebecca Z. 

TITLE=Specific Vagus Nerve Lesion Have Distinctive Physiologic Mechanisms of Dysphagia

JOURNAL=Frontiers in Neurology

VOLUME=Volume 10 - 2019

YEAR=2019

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2019.01301

DOI=10.3389/fneur.2019.01301

ISSN=1664-2295

ABSTRACT=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. In an infant pig model, we have shown that while aspiration increases after lesion of SLN or RLN, specific changes in swallowing physiology are different in each case. Post SLN lesion, bolus volume is larger, and bolus volume does not predict whether aspiration will occur. Conversely, post RLN lesion bolus volume is smaller and bolus volume does predict aspiration. Similarly, tongue kinematics during swallowing respond differently to RLN lesion and SLN lesion and airway protection outcome. 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.