Handy measurement for tongue motion and coordination with laryngeal elevation at swallowing

At the oral stage of swallowing, the tongue plays a major role and proper tongue performance is necessary to form the bolus and transfer it to the pharynx. For the present study we built a prototype device for safe and handy objective estimation of tongue motion and coordination with laryngeal elevation at swallowing. The device records tongue pressure by means of two strain gauge pressure transducers aligned 20 mm apart on a brass strap placed along the palatal midline. Laryngeal vibration is recorded with piezo-electric acceleration transducers. Time differences between pressure onset at the anterior and posterior transducers and the first spike from laryngeal vibration are measured. Ten healthy subjects were asked five times to swallow 5 mL of water. Pressure onset at the anterior transducer preceded posterior pressure by 294 +/- 164 ms. Given the distance between the transducers, the tongue contracted (squeezed) at a speed of 93 +/- 60 mm s(-1). Laryngeal vibration occurred 671 +/- 175 ms after the onset of anterior pressure. There was considerable variation in these parameters between subjects. Though the data is limited, the device successfully and easily revealed certain aspects of tongue motion and coordination with laryngeal elevation.