Noninvasive swallowing test for young healthy adults: Finding the best location to monitor thyroid cartilage movements

Noninvasive electrophysiological swallowing monitoring has become commonly used for swallowing studies due to its accuracy and lack of radiation exposure. Excursion of the thyroid cartilage plays a crucial role in airway protection during oropharyngeal swallowing. Therefore, monitoring this excursion is essential in swallowing studies. The level of the thyroid cartilage and the level at which cricothyroidotomy is performed are two locations at which piezoelectric sensors can be placed to measure excursion activities. This study aimed to find the best location for the placement of piezoelectric sensors for detecting thyroid cartilage excursion movements during noninvasive swallowing tests. Nineteen healthy young adults (9 men, 10 women), aged 20 to 32 years (mean: 24.5 ± 4.0 years), were recruited for the analysis of swallowing signals while drinking six different bolus volumes of water. The quantitative excursion signals of the thyroid cartilage integrated with the activities of the submental muscles were compared between the two piezoelectrical sensor placement locations and between men and women. Recording at the thyroid cartilage level showed higher excursion amplitude, earlier onset latency, and longer excursion duration under most bolus conditions compared to those recorded at the cricothyroidotomy level, although some conditions did not reach statistical significance. Earlier onset latency makes detecting the delayed latency in dysphagia easier, and higher amplitude facilitates signal detection on the skin surface. Thyroid cartilage recordings did not differ significantly between men and women. The data suggest that the thyroid cartilage level is more suitable for piezoelectric sensor placement for recording swallowing signals than the cricothyroidotomy level.