Swallowing kinematics and airway protection after palatal local anesthesia in infant pigs

Abstract

Objective Abnormal kinematics during swallowing can result in aspiration which may become life threatening. We tested the role of palatal sensation in the motor control of pharyngeal swallow in infants. Study Design In eight infant pigs, we reduced palatal sensation using local anesthesia (PLA) and measured the impact on swallowing kinematics and airway protection. Methods The pigs drank milk containing barium while we simultaneously recorded videofluoroscopy and electromyography from fine wire bipolar electrodes in several hyolaryngeal muscles. We compared these results to control feedings and feedings following palatal saline injections (PSA). Results After PLA, four pigs had extreme jaw movements and abnormal tongue movement uncharacteristic of sucking. For this reason, we evaluated differences between these “Group B” pigs and the others that could suck normally after PLA, “Group A”. In the four Group A pigs, after PLA there was less hyoid elevation (p<0.001) but normal jaw and tongue movements. In Group B, in addition to greater jaw movement (p<0.001) there was more anterior and superior tongue movement (p<0.001) and a larger range of hyoid movement (p<0.001) Conclusion The airway was protected in all of the pigs, indicating that these changes allowed successful adaptation to the reduction in palatal sensation. However, the oral and pharyngeal phases of the swallow were functionally linked and trigeminal sensation influenced the motor control of the pharyngeal swallow.

Variation in the Timing and Frequency of Sucking and Swallowing over an Entire Feeding Session in the Infant Pig Sus scrofa

“…Infant pigs have been used in previous studies of normal feeding and swallowing neurophysiology, and thus a large body of comparable data exists for comparison with the results of this study [4, 12, 17, 21, 22]. The data used here were collected as control data in other studies of dysphagia [8, 9, 23, 24]. The methods used are described in detail in those articles and briefly reviewed here.…”

Animal Models for Dysphagia Studies: What Have We Learnt So Far

“…Surgical or pharmacological models of stroke in rodents have been common, but are now being developed and validated for examining dysphagia [19, 44]. Injuries that are associated with dysphagia, such as damage to branches of the vagus nerve, recurrent or superior laryngeal nerve [11, 12, 16, 38], or other sensory deficits [18], can be relatively easily duplicated in animal models.…”

Pre-pharyngeal Swallow Effects of Recurrent Laryngeal Nerve Lesion on Bolus Shape and Airway Protection in an Infant Pig Model

“…However, recent work has indicated that airway protection deficits following RLN lesion are associated with changes in the timing and extent of tongue movements during intraoral transport and the swallow [7]. In addition, both anesthesia [8] and stimulation [9] of oral sensory pathways change swallow parameters and airway protection outcomes, highlighting the importance of sensory modulation of the swallow by structures throughout the oral, pharyngeal, and laryngeal complex. This suggests that the biomechanics of transport of the liquid bolus from the valleculae to the pharynx may be modified in infants with a recurrent laryngeal nerve lesion.…”

“…We use our validated infant pig model [8,11,12] in order to do controlled nerve injuries and collect amounts of data impossible in vulnerable infant clinical populations. Infant pigs are a good model for infant humans through similar size [13], similar anatomy (a fleshy, muscular tongue, muscular cheeks and an intranarial larynx) and a similar mode of drinking (tongue based suction rather than lapping) [14].…”