B-mode and M-mode Ultrasonography of Tongue Movements during Swallowing

Abstract

This study investigated the possibility of using B-mode and M-mode ultrasonography to differentiate between the visceral and somatic swallowing patterns. Tongue movements during empty swallowing by 11 volunteers with a visceral swallowing pattern were traced in B-mode and M-mode ultrasound imaging before and after successful myofunctional therapy. Thirteen subjects with a somatic swallowing pattern served as the control group. We examined and compared the B-mode sequences and M-mode images of at least six of each study subject's swallowing processes for reproducible characteristics and parameters. We observed wide intraindividual variability, making interindividual comparison difficult or meaningless. We identified no qualitative characteristic features in B-mode imaging that could be designated as solely visceral or physiological swallowing movements. There was no obvious intraindividual reproducibility in the M-mode sonogram of the swallowing act. Given the experimental set-up we used (without a submandibular cushioning pad), it was not possible to differentiate individual swallowing phases, that is, the initial, transporting, and returning phases, on the M-mode images based on characteristic trace points, as described in the literature. We determined the amplitude and velocity of vertical tongue movement as well as total swallowing duration on the M-mode images. These parameters revealed wide intra- and interindividual variability. No qualitative differences could be established in B-mode imaging with the ultrasound method selected for this study. The parameters that could be measured on the M-mode images are not suitable for differentiating between visceral and somatic swallowing.