Respiratory Movement of Upper Airway Tissue in Obstructive Sleep Apnea.

STUDY OBJECTIVES

To measure real-time movement of the tongue and lateral upper airway tissues in obstructive sleep apnea (OSA) subjects during wakefulness using tagged magnetic resonance imaging.

DESIGN

Comparison of the dynamic imaging of three groups of increasing severity OSA and a control group approximately matched for age and body mass index (BMI).

SETTING

Not-for-profit research institute.

PARTICIPANTS

24 subjects (apnea hypopnea index [AHI] range 2-84 events/h, 6 with AHI < 5 events/h).

METHODS

The upper airway was imaged awake in two planes using SPAtial Modulation of Magnetization (SPAMM). Tissue displacements were quantified with harmonic phase analysis.

MEASUREMENTS AND RESULTS

All subjects had dynamic airway opening in the sagittal plane associated with inspiration. In the nasopharynx, the increase in airway cross-sectional area during inspiration correlated with minimal cross-sectional area of the airway (R = 0.900, P < 0.001). AHI correlated negatively with movement of the nasopharyngeal lateral walls (R = - 0.542, P = 0.006). Four movement patterns were observed during inspiration: "en bloc" anterior movement of the whole posterior tongue; movement of only the oropharyngeal posterior tongue; bidirectional movement; or minimal movement. Some subjects showed different inspiratory movement patterns with different breaths. A low AHI (< 5) was associated with en bloc movement (P = 0.002).

CONCLUSIONS

Inspiratory movement of the tongue varied between and within subjects, likely as a result of local and neural factors. However, in severe OSA inspiratory movement was minimal.

CITATION

Brown EC; Cheng S; McKenzie DK; Butler JE; Gandevia SC; Bilston LE. Respiratory movement of upper airway tissue in obstructive sleep apnea. 2013;36(7):1069-1076.