Temporal and kinematics changes in jaw movement during feeding following chemoradiation to the rat submental muscles

Abstract

Head and neck cancer patients treated with chemoradiation can develop radiation-induced dysphagia, which can significantly impact their quality of life. The submental muscles of the floor of mouth, such as the mylohyoid and geniohyoid, are at high risk for radiation-associated impairments in swallowing function. Prior work has shown that irradiating the submental muscles reduces the rate of tongue movement. During feeding, there is functional linkages between the jaw and tongue; therefore, an alteration in jaw movement could influence the position/shape of the tongue. The purpose of this study was to determine if chemoradiation treatment to the submental muscles alters jaw movement during eating. We hypothesized that the jaw speed and distance of movement during feeding would be modified following radiation treatment. Videofluoroscopic swallow study (VFSS) was performed on 18 Sprague-Dawley rats 1-month after chemoradiation, radiation alone or no treatment. Radiation was targeted to the submental muscles (12 fractions of 4Gy given three days a week for four weeks). Four cycles of 1mg/kg of cisplatin were administered concurrently with radiation. Rodents were provided peanut butter with 40% w/v barium and video recordings were taken at 250 frames per second with a customized c-arm. Jaw position along the xy axis was measured relative to the hard palate. Temporal and kinematic measures of the vertical movement of the jaw were analyzed. Significant decreases in jaw distance (p<0.03) and speed (p<0.02) traveled during licking were observed post treatment compared to untreated controls. The distance traveled during opening and closing phases of the jaw cycle were found to be decreased (both p<.03) following chemoradiation and radiation treatment. Results demonstrate that radiation-based treatments to the submental muscles impair jaw movement. The observed changes in jaw kinematics could potentially influence tongue position and shape during feeding. The Ar-Hale Family Foundation; Jewish Heritage Fund for Excellence Grant This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.