Dynamics of Upper Airways During the Muller Maneuver in Healthy Subjects: A Cine MRI Study

The Muller maneuver has been widely applied to mimic the pathophysiological condition of obstructive sleep apnea (OSA) during wakefulness. We applied cine MRI to elucidate dynamics of the upper airway during the Muller maneuver in healthy subjects (n = 7). Three sets of images (during quiet nose breathing, quiet mouth breathing, and Muller maneuver) were recorded on sagittal midline plane together with impedance pneumography. The position of the tongue root changed during a respiratory cycle when subjects breathed quietly. At the early inspiratory phase the tongue root moved forward and upward, the retroglossal airway size increased toward the middle of inspiration, and the airway size became smaller again toward the end of inspiration. During expiration the airway size became further smaller. When the subject performed the Muller maneuver, the movement of the oropharynx and its narrowing were greater than those of the velopharynx. However, the airway was not completely obstructed. A relatively large morphological change was observed in the retropalatal and retroglossal regions with the backward and downward motion of the tongue root and flattening of the tongue shape during the Muller maneuver. Although patterns of upper airway narrowing and tongue shape alterations were variable among subjects, upper airway narrowing was commonly prominent in the retroglossal area. Cine MRI with the Muller maneuver enables to visualize the upper airway dynamics and could be easily applied to evaluate upper airway collapsibility during wakefulness.