[Videofluorographic assessment of swallowing function in patients with Duchenne muscular dystrophy]

To identify the characteristics of swallowing function in patients with Duchenne muscular dystrophy (DMD).

Swallowing function was evaluated using videofluorography (VF) in a cross-sectional observational study of 102 DMD patients (mean age 21.5 years) who had dysphagia or in whom dysphagia was suspected based on clinical signs. Reduced tongue movement, impaired bolus transport to the pharynx, decreased pharyngeal contraction, bolus delivery into the airway, and bolus residue at the epiglottic vallecula and at the piriform recess were qualitatively evaluated for test swallows of jelly and juice. During VF, the length of time of both the oral and pharyngeal phases of swallowing was measured in 59 patients.

Patients started to show oral phase abnormalities in their mid-teens and pharyngeal phase abnormalities such as pharyngeal residue around age 20. Oral phase abnormalities was higher with juice than with jelly. Total oral/pharyngeal transit duration was longer with age, and total duration of hyoid maximum elevation was shorter with age.

The weak positive correlation of total oral/pharyngeal transit duration and age was presumably due to gradual onset of functional abnormalities associated with deteriorated swallowing muscles starting in the teenage years. Reduced tongue movement and impaired bolus transport to the pharynx was more common in teenage DMD patients because they have limited tongue movements associated with structural abnormalities such as macroglossia and open bite. VF showed that the swallowing difficulties were more severe during the oral phase than in the pharyngeal phase in the teenage patients. The pharyngeal phase disorders such as pharyngeal residue and decreased pharyngeal contraction were seen more often in the patients in their 20s, presumably due to deterioration of swallowing muscles that becomes more apparent in the older age group.