A Trial of Imaging of Swallowing Sounds

―Possibility of clinical application to dysphagic patients―

Abstract

【Objective】Video-fluorographiec (VF) and endoscopic examinations are generally used te evaluate patients with dysphagia. However, the former examinations inevitably require substantial facilities and radiation hazards, and so their use in nursing homes or institutes is restricted. We have therefore developed an imaging analysis of swallowing sounds called video-sound imaging analysis (VS) and have examined the possibility of its clinical application.

【Subjects and methods】Image data were taken from healthy men through an accelerated transducer placed on the lateral border of the trachea immediately inferior to the cricoid cartilage on the neck. VS waveforms displayed on the universal ultrasonograph were recorded digitally on a hard disk recorder. VF images were also stored in another hard disk. VS and VF monitor images were simultaneously recorded by digital video camera during swallowing of diluted 30% barium sulfate solution, jelly, rice, and thickened water. Liquid swallowing and modified swallowing with holding up the laryngeal elevation by voluntarily manipulated maneuver, were compared, and the effect of food texture was examined. We reviewed the position of the bolus and wave onset by comparing VF images with VS waveforms. We compared the coefficients of variance to identify the value of the repand area divided by duration (A/t).

【Results】The VS waveforms consisted of three main complexes (Sa, Sb, Sc). VF images revealed that Sa waveforms were in the passage from the oral cavity to the vallecula, Sb from the vallecula to the orifice of the esophagus, and Sc in the upper esophagus. The origin of wave complexes is still being examined, however, larynx depression suggested one of the probable components of Sc wave complexes. Comparing A/t, it showed that Sb is larger than Sa/Sc, but regarding the coefficient of variance of A/t, Sb tended to be smaller than Sa/Sc.

【Discussion】VS wave complexes were significantly demonstrated in the whole process of swallowing movements and total deglutition dynamies, and although each component has not yet been defined, it is suggested that the calculated A/t can be used to.evaluate VS. In the near future, VS is expected to provide a new method for evaluating the swallowing mechanism and functional disabilities of patients with dysphagia without radiation hazards.