The Effect of Preterm Birth and Recurrent Laryngeal Nerve Lesion on Palatopharyngeal Arch Function During Feeding

Abstract

Feeding in infant mammals requires the precise coordination of multiple oropharyngeal structures, including the palatopharyngeal arch. During a typical swallow, the activity of the palatopharyngeus muscle produces constriction of the arches and lowers the soft palate, which may be responsible for flipping of the epiglottis to cover the airway. Most research on the role of the palatopharyngeal arches in swallowing has been limited to pharyngeal manometry, which provides insight into the relative pressures in the oropharynx during swallowing. Studies using manometry in preterm infants, or in those with iatrogenic sequelae such as recurrent laryngeal nerve (RLN) damage, suggest differences in function, but not on how the structures in the oropharynx move to contribute to those changes in function. In this study, we assessed palatopharyngeal arch kinematics during feeding by using our validated infant pig model to determine the impact of birth status (preterm versus term), lesion status (lesioned RLN versus intact) and their interaction on feeding performance. We placed tantalum radio‐opaque beads into relevant anatomical structures of 16 infant pigs, including the palatopharyngeal arches, the tongue, the hard and soft palate, and the nose. We recorded feeding at both seven and 17 days postnatal via biplanar high‐speed videofluoroscopy (100fps) across a total of 584 swallows. Using XMALab, we tracked the three‐dimensional movement of the arches relative to a rigid body comprised of the markers in the hard palate and the nose. We then used custom MATLAB code to calculate the three‐dimensional excursion of the arches during a swallow, as well as the timing of constriction initiation, and the point of maximal constriction during a swallow. We found that preterm infants had more variable arch excursion than term infants, and RLN lesion increased excursion for both term and preterm infants although there were minimal differences in arch excursion within an age between term and preterm infants. Term infants also reached maximal arch constriction later than preterm infants, most likely due to their larger arch excursion and larger bolus volume. Lesion infants, both term and preterm, also had delayed maximal arch constriction during swallows, although day 17 term lesion infants reached maximal constriction earlier than term day 17 infants. Lesion resulted in delayed initiation of arch constriction, which did not change with age, although older term infants exhibited later arch constriction initiation than older preterm infants. Our results show that preterm birth and RLN lesion have distinct yet pervasive effects on infant feeding. Altered feeding performance in these neurologically compromised infants may be due in part to changes in the activity of the palatopharyngeal arches.Support or Funding InformationNIH R01HD088561