Objectives: Swallowing is a complex sensorimotor event that
contains both voluntary and involuntary movements of the orofacial, pharyngeal,
laryngeal and esophageal regions and requires coordination of those muscle
functioning. A loss of the coordination is associated with dysphagia leading to
coughing, pulmonary aspiration and crucial pneumonia. A variety of food
consistencies and body and/or head positions are frequently presented for the
evaluation and treatment of dysphagia. In this study, the effects of food
consistency and body posture on the entire swallowing function were
investigated quantitatively. Methods: Thirteen healthy volunteers without
complaint of dysphagia or other oropharyngeal ploblems were included in this
study. The subject was required to swallow test foods (5 ml) with three
different hardness and liquid by the cue, which was so called command swallow.
They were also tested in two different postures which were upright and body
reclinced at 30 degrees. The videofluorography as well as the tongue pressure
and electromyographic activity of suprahyoid muscle were recorded. Results:
Swallowing-related movements varied among the foods and postures. Tongue
pressure was increased during hard food swallowing as compared with soft food
or liquid.
Oral transit time was increased while clearance time was
decreased during hard food swallowing as compared with soft food or liquid.
When compared between the postures, tongue pressure and bolus flow time except
oral transit time tend to be larger in the body reclined than upright. Contrary
to this, patterns of suprahyoid muscle activity hardly changed regardless of
difference in the posture. Conclusion: The results suggest that food
consistency and subject's posture may affect the swallowing function in terms
of swallow-related tongue activity and the bolus flow time. Furthermore,
simultaneous recordings of videofluorography, electromyography and tongue
pressure can be available to evaluate the temporal relationship between
biomechanical function and bolus flow during swallowing movements.
