A novel ultrasound technique to measure genioglossus movement in vivo

Abstract

Upper airway muscles are important in maintaining airway patency. Visualization of their dynamic motion should allow measurement, comparison, and further understanding of their roles in healthy subjects and those with upper airway disorders. Currently, there are few clinically feasible real-time imaging methods. Methods such as tagged magnetic resonance imaging have documented movement of genioglossus (GG), the largest upper airway dilator. Inspiratory movement was largest in the posterior region of GG. This study aimed to develop a novel ultrasound (US) method to measure GG movement in real time. We tested 20 healthy, awake subjects (21-38 yr) breathing quietly in the supine posture with the head in a neutral position. US images were collected using a transducer positioned submentally. Image correlation analysis measured regional displacement of GG within a grid of points in the midsagittal plane throughout the respiratory cycle. Typically, motion began before inspiratory flow in an anteroinferior direction and peaked in midinspiration. Average peak displacements of the anterior, posterior, superior, and inferior grid points were 0.44 ± 0.23 (mean ± SD), 0.57 ± 0.35, 0.38 ± 0.20, and 0.62 ± 0.41 mm, respectively. Largest displacements occurred in the most inferoposterior part (0.70 ± 0.48 mm). This method had good intrarater repeatability within the same testing session, as well as across sessions. We have devised a simple noninvasive US method, which should be a useful tool to assess GG movement in normal subjects and those with sleep-disordered breathing.

Tongue sonography: An introduction

“…Tongue sonography requires ultrasound equipment that supports a range of high‐resolution transducers 04 . At our institution, a 14 MHz linear transducer is utilised for the majority of submental tongue imaging.…”

“…Ultrasound can reliably resolve soft tissue structures and simultaneously evaluate for nodal disease in the neck, making it ideal for screening purposes 10 . It displays cross‐sectional anatomy and tissue motion in real‐time 4 . As a result, transcervical ultrasound has been studied as a means of staging oral tongue tumours, but it has not been as widely studied or accepted for this purpose as intraoral ultrasound, particularly in the last two decades.…”

“…The tongue is a fundamental component of the oral cavity with important physiological roles in mastication, gustatory and salivary function, respiratory control, vocalisation 4 and co‐ordinated swallowing 5 …”

“…Fibres located in the posterior tongue display a uniform and parallel arrangement, whereas fibres in the anterior tongue are progressively non‐uniform in orientation. These divergent muscle patterns result in a heterogeneous echotexture on ultrasound due to anisotropy and individual patient's tongue characteristics 4 …”

Regional respiratory movement of the tongue is coordinated during wakefulness and is larger in severe obstructive sleep apnoea

“…Using tagged MRI, dilatory tongue movements have been reported during respiration in healthy adults and OSA patients (Cheng et al 2008;Brown et al 2013;Cheng et al 2014;Cai et al 2016;Kwan et al 2019). Previous studies of the human upper airway indicated that the posterior region of the tongue moves anteriorly during inspiration resulting in airway dilatation (Cheng et al 2008;Kwan et al 2014Kwan et al , 2018. In particular, it was found that airway dilatation during inspiration is larger in the presence of a narrow airway in healthy individuals (Cheng et al 2014), differs between heathy controls and people with OSA, but differs between people with and without OSA and varies with OSA severity (Brown et al 2013).…”