Tongue movements and teat compression during bottle feeding: A pilot study of a quantitative ultrasound approach

Nutritive sucking is a complex process, essential to proper growth and development. The complexity of this oral sensorimotor activity includes movements of the tongue and jaw. Tongue movements during nutritive sucking can only be visualized with instrumented methods such as ultrasound. Until now, studies using ultrasound during nutritive sucking performed measurements on each individual ultrasound image frame, which was quite time-consuming. The aim of this pilot study was to automatically process ultrasound video recordings in healthy infants during bottle feeding to measure teat compression and tongue movements. Tongue movements and teat compression during bottle feeding were visualized and recorded using 2D dynamic ultrasound imaging. A custom-made semi-automated analysis-routine was developed. Teat compression was expressed as the median difference in teat diameter during the recording. Tongue movements were expressed as the displacement of the tongue along four evenly distributed image lines and the corresponding time-shifts between those lines. The recordings of 12 out of 14 participants were adequate for the analysis of tongue movements. Teat compression could be analysed in the recordings of 6 participants. The reliability of our analysis-routine was considered to be good, and the analysis-routine was more time-efficient than manual frame-by-frame analysis. This quantitative analysis-routine is a promising tool, that can be used efficiently and accurately in the future to collect normative data that can serve as reference values to distinguish normal from abnormal tongue movements in infants with feeding difficulties.