Dynamic alterations of the tongue in obstructive sleep apnea-hypopnea syndrome during sleep: analysis using ultrafast MRI.

Patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) were evaluated using ultrafast magnetic resonance imaging (UMRI) while asleep and awake to analyze tongue changes. The upper airway of 21 OSAHS patients and 20 normal controls were examined during sleep using UMRI. A series of midline sagittal images of the upper airway were obtained to measure dynamic changes in tongue size and the distance from the tongue to the x-axis (an extended line from the anterior nasal spine to posterior nasal spine) and the y-axis (a perpendicular line from the center of the pituitary to the x-axis). The maximum and minimum sagittal diameters of the tongue were shorter in the OSAHS group than in the control group (P<0.01) while awake, whereas the difference between the maximum and minimum vertical diameters of the tongue and the upper and central part of tongue between the posterior border and the retropharyngeal wall were greater (P<0.05). During sleep, the maximum values and differences between the maximum and minimum tongue sizes in the OSAHS group were larger than in the control group (P<0.05), whereas the minimum values were lower than in the control group (P<0.01). Tongue size significantly differs between OSAHS patients and normal controls during sleep. The tongue tends to move downward during OSAHS, which may be attributed to increased upper airway resistance.