Tongue and Lateral Upper Airway Movement with Mandibular Advancement

Abstract

Study Objectives: To characterize tongue and lateral upper airway movement and to image tongue deformation during mandibular advancement. Design: Dynamic imaging study of a wide range of apnea hypopnea index (AHI), body mass index (BMI) subjects. Setting: Not-for-profit research institute. Participants: 30 subjects (aged 31-69 y, AHI 0-75 events/h, BMI 17-39 kg/m 2 ). Interventions: Subjects were imaged using dynamic tagged magnetic resonance imaging during mandibular advancement. Tissue displacements were quantified with the harmonic phase technique. Measurements and Results: Mean mandibular advancement was 5.6 ± 1.8 mm (mean ± standard deviation). This produced movement through a connection from the ramus of the mandible to the pharyngeal lateral walls in all subjects. In the sagittal plane, 3 patterns of posterior tongue deformation were seen with mandibular advancement-(A) en bloc anterior movement, (B) anterior movement of the oropharyngeal region, and (C) minimal anterior movement. Subjects with lower AHI were more likely to have en bloc movement (P = 0.04) than minimal movement. Anteroposterior elongation of the tongue increased with AHI (R = 0.461, P = 0.01). Mean anterior displacements of the posterior nasopharyngeal and oropharyngeal regions of the tongue were 20% ± 13% and 31% ± 17% of mandibular advancement. The posterior tongue compressed 1.1 ± 2.2 mm supero-inferiorly. Conclusions: Mandibular advancement has two mechanisms of action which increase airway size. In subjects with low AHI, the entire tongue moves forward. Mandibular advancement also produces lateral airway expansion via a direct connection between the lateral walls and the ramus of the mandible.

A novel ultrasound technique to measure genioglossus movement in vivo

“…Fluoroscopy involves exposure to radiation and is unable to characterize the internal deformation of soft tissues of the tongue (38,41). MRI and computed tomographic imaging have also been used to evaluate the upper airway muscles and lumen diameters in normal subjects and subjects with sleep-disordered breathing (8,10,14,48). However, these techniques are expensive, time-consuming, and less likely to gain widespread clinical use.…”

Enlargement of the Pharynx Resulting From Surgically Assisted Rapid Maxillary Expansion

“…Some lateral enlargement of the pharynx in the middle and lower segments was expected from SARME; however, the 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 results obtained (16.96 and 24.87%, respectively) exceeded expectations. More studies must be performed to explain this lateral expansion because the same effect also occurs with the use of mandibular advancement appliances 25,26 that only promote the anterior displacement of the mandible, without any change in the transverse dimension. This lateral enlargement of the pharynx likely occurs in these levels owing to the traction of t...…”

Peripharyngeal tissue deformation and stress distributions in response to caudal tracheal displacement: pivotal influence of the hyoid bone?

“…Recent magnetic resonance (MR) imaging studies in awake human subjects using specialized MR imaging protocols (i.e., SPAMM) have demonstrated local peripharyngeal tissue deformation and movement, under a number of conditions, which was shown to be different along the length of the upper airway (7,8,11,12). The majority of the tissue motion in these studies was active (i.e., during inspiration).…”

“…Our laboratory has previously investigated the complex and nonuniform behavior of peripharyngeal tissues in anesthetized animals by examining tissue pressures, i.e., extraluminal tissue pressure (ETP) (24 -29). More recently, anesthetized animal (4,5) and awake human studies (7,8,11,12) have approached this question by measuring peripharyngeal tissue deformation (strain). Such studies support a model that includes nonuniform tissue behavior (in both space and stiffness) to better describe the mechanics of the upper airway.…”