Long-term changes in bolus parameters during swallowing post-chemoradiation treatment.

Current treatment for oropharyngeal cancer involves chemoradiation, which can have profound effects on swallowing function. Submental muscle activity is critical for airway protection and bolus transit but is highly susceptible to radiation-related swallowing impairments. This study examined whether chemoradiation targeting the submental muscles leads to measurable changes in esophageal distension during swallowing in a rodent model. We hypothesized that rats receiving chemoradiation would exhibit aberrant esophageal distension compared to chemotherapy-only controls. Twenty male rats underwent four cycles of cisplatin concurrently with either radiation or sham radiation. High-speed videofluoroscopy swallow studies were conducted pre- and post-treatment with thin liquids to analyze esophageal distension, bolus area, and onset of hyoid elevation. Significant increases in esophageal distension were observed at both 5- and 8-months post-treatment (p< 0.001). Bolus size within the esophagus increased at 3-, 7-, and 8-months (p< 0.001). The hyoid began elevating earlier relative to bolus transport starting at 2-months and persisted through 8-months (p< 0.04). These findings demonstrate persistent alterations in swallowing function following chemotherapy with or without radiation treatment, reinforcing the need for targeted rehabilitation strategies to mitigate long-term swallowing impairments.