Abstract
We developed a jaw opening sthenometer to assess the swallowing function and measure the jaw-opening force of healthy volunteers. In the present study, we investigated the relationship between the jaw-opening force and specific swallowing abnormalities, such as aspiration and pharyngeal residue. The purpose of this study was to examine the relationship between jaw-opening force and swallowing impairment. We examined 95 patients complaining of dysphagia and with symptoms of dysphagia with chronic underlying causes（male： 49, female： 46, mean age： 75.4± 9.7 males and 79.3±9.6 females). The jaw-opening force in the patients with aspiration (male： 4.1±2.8 kg, female： 3.4±1.7 kg) were significantly lower than in those without aspiration (male： 5.6±2.9 kg, female： 4.4±1.8 kg) in both sexes. The jaw-opening force in the patients with pharyngeal residue in the valleculae (male： 4.2±2.3 kg, female： 3.6±1.4 kg) was significantly lower than in those without pharyngeal residue in the valleculae (male：8.5± 3.4 kg, female：5.0±2.0 kg) in both sexes. The jaw-opening force in the patients with pharyngeal residue in the pyriform sinus (male： 4.1±2.1 kg, female： 3.1±1.5 kg) were significantly lower than in those without pharyngeal residue in the valleculae (male： 6.7±3.6 kg, female： 4.7±1.9 kg) in both sexes. There are several causes for aspiration, for example, absence or delay of pharyngeal swallowing, incomplete airway closure and decreased elevation of hyoid and larynx. The last factor is caused by decreased suprahyoid muscle contraction. The pharyngeal residue mainly occurs by incomplete epiglottic tilting and incomplete pharyngeal shortening, resulting from decreased elevation of the hyoid and larynx. Therefore, the assessment of jaw-opening force for swallowing function can be a predictor of aspiration and pharyngeal residue.
