Influence of mastication and salivation on swallowing in stroke patients

Objective: To determine differences of the oral swallowing functions between stroke and normal subjects and to identify those factors affecting dysphagia of stroke patients. Design: Case-control study. Setting: University hospital. Participants: Ten stroke and 10 healthy subjects, Interventions: Not applicable. Main Outcome Measures: Resting saliva flow rate, the total number of chews, and the duration of the oral phase until onset of pharyngeal swallow, and food viscosities both before and after the oral phase using diluted barium, pudding, thick rice gruel. and curd type yogurt. Results: The viscosity of all test foods was significantly reduced after the oral phase in both groups (P <.01). Resting saliva flow rate and the viscosity of thick rice gruel after the oral phase in the stroke group were significantly lower than in the control group (P <.01). However, there were no differences in the viscosities of the other foods between both groups. And a longer oral phase and a greater number of chews prior to pharyngeal swallow were revealed in the stroke group than in the control group (P <.01). Conclusions: This study shows that the food requiring mastication demands a longer oral phase and a greater number of chews, and has more altered rheologic characteristics during the oral phase in stroke patients. These findings suggest that masticatory function is impaired in stroke patients, which may contribute to their swallowing dysfunction.