Sucking and swallowing rates after palatal anesthesia: an electromyographic study in infant pigs

Abstract

Infant mammalian feeding consists of rhythmic suck cycles and reflexive pharyngeal swallows. Although we know how oropharyngeal sensation influences the initiation and frequency of suck and swallow cycles, the role of palatal sensation is unknown. We implanted EMG electrodes into the mylohyoid muscle, a muscle active during suckling, and the thyrohyoid muscle, a muscle active during swallowing, in eight infant pigs. Pigs were then bottle-fed while lateral videofluoroscopy was simultaneously recorded from the electrodes. Two treatments were administered prior to feeding and compared with control feedings: 1) palatal anesthesia (0.5% bupivacaine hydrochloride), and 2) palatal saline. Using the timing of mylohyoid muscle and thyrohyoid muscle activity, we tested for differences between treatment and control feedings for swallowing frequency and suck cycle duration. Following palatal anesthesia, four pigs could not suck and exhibited excessive jaw movement. We categorized the four pigs that could suck after palatal anesthesia as group A, and those who could not as group B. Group A had no significant change in suck cycle duration and a higher swallowing frequency after palatal saline ( P = 0.021). Group B had significantly longer suck cycles after palatal anesthesia ( P < 0.001) and a slower swallowing frequency ( P < 0.001). Swallowing frequency may be a way to predict group membership, since it was different in control feedings between groups ( P < 0.001). The qualitative and bimodal group response to palatal anesthesia may reflect a developmental difference. This study demonstrates that palatal sensation is involved in the initiation and frequency of suck and swallow cycles in infant feeding.

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

“…Extensive sensory motor connections exist between the oral cavity and the swallow reflex [9,32]. The results here indicate that sensory motor connections are ubiquitous throughout the oro-pharyngeal-laryngeal system, although their neurological basis is still poorly understood [33,34].…”

The Physiologic Impact of Unilateral Recurrent Laryngeal Nerve (RLN) Lesion on Infant Oropharyngeal and Esophageal Performance

“…The different patterns of change in variation of IMPAS versus average IMPAS score through time suggest that individuals respond to the loss of RLN sensory and motor function in different ways, reflecting differing amounts of functional impairment despite consistent lesion. Similar variation in oropharyngeal function following sensory lesion exists in the qualitatively distinctive responses to palatal anesthesia in infant pigs [13]. Further work is needed to test these hypotheses against other physiological mechanisms (such as differing inflammatory responses), and to test whether difference lie in central connectivity or peripheral overlap of innervation fields.…”

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.…”