Pharyngeal effects of bolus volume, viscosity, and temperature in patients with dysphagia resulting from neurologic impairment and in normal subjects

The oropharyngeal swallow of 10 patients with mild dysphagia at 3 weeks after a cerebrovascular accident (stroke), 10 normal subjects, and 8 neurologically impaired patients with moderate to severe dysphagia was studied videofluorographically to examine the effects of 2 bolus temperatures (room temperature and 33°F), 2 volumes, and 2 viscosities on the durations of pharyngeal stage swallow events and the frequency and nature of oropharyngeal swallowing problems and bolus transit. Normal subjects exhibited significantly longer pharyngeal response times and longer laryngeal elevation only for 1 ml cold liquid. The stroke patients and the 8 significantly dysphagic neurologically impaired patients exhibited very few significant effects of temperature on swallowing disorders or swallow measures. Increases in bolus volume and viscosity decreased pharyngeal delay times in both neurologically impaired patient groups. Stroke patients exhibited significantly longer pharyngeal delay times but shorter pharyngeal response times, laryngeal closure, cricopharyngeal opening, and laryngeal elevation than normal subjects on some bolus volumes and viscosities. Results are discussed in terms of the potentially therapeutic effects of bolus volume and viscosity.