Kinetic analysis of retropharyngeal wall during swallowing

Abstract

We focused on the motion of the retropharyngeal wall during the swallowing movement to investigate the cause of dysphagia of head and neck cancer patients who underwent surgery. We also devised a method of kinetic analysis using video-fluorography (VF) images on a computer, and compared the results with the dysphagia level.
The VF image of 29 head and neck cancer patients were analyzed with two-dimensional video measurement software. We calculated the thickness of the retropharyngeal wall of the second, third, and fourth cervical vertebrae during swallowing and measured the time when the thickness was maximum at each vertebra. To measure the dysphagia level, we quantified the remaining contrast media in the epiglottic vallecula or the piriform fossa and the aspiration amount based on interpretation of the VF images.
Before surgery, all patients showed normal peristaltic motion in which the thickest point of the retropharyngeal wall was moved sequentially from the second to the fourth vertebra. Some patients, however, showed abnormal peristaltic motion after surgery. These cases showed high dysphagia scores with a significant difference from normal peristaltic motion cases.
Computational analysis of the VF images enabled us to evaluate the motions of the retropharyngeal wall along the time axis. A change in the kinetic pattern of the retropharyngeal wall caused by surgery can be substantially related to dysphagia.