Quantitative three-dimensional ultrasound analysis of tongue protrusion, grooving and symmetry: data from 12 normal speakers and a partial glossectomee

The functional determinants for a good speech outcome after a partial tongue resection and reconstruction are not well established. The purpose of the present study was to assess the protrusion, grooving and symmetry of the tongue during sustained speech sound production using three-dimensional ultrasound. The participants were twelve normal speakers and one partial glossectomee. The three-dimensional ultrasound volumes of nine sustained speech sounds were measured in three sagittal planes. The data were re-plotted as three-dimensional surfaces. We calculated an anteriority index, a concavity index and an asymmetry index. The glossectomee's postoperative surface plots were characterized by asymmetry and convexity of the tongue surface. The anteriority index illustrated that the glossectomee's ability to protrude her tongue was not affected by the operation. The concavity index captured a decrease in midsagittal grooving in the glossectomee's tongue. The asymmetry index demonstrated height differences in the elevation of the right and left side of the tongue. We conclude that three-dimensional ultrasound offers us a practical tool for the detailed and concise assessment of the lingual shape and deformation in patients undergoing glossectomy surgery.