Case Study: Imaging of Apnea Termination in a Patient with Obstructive Sleep Apnea during Natural Sleep

A 55-year-old woman who presented to the sleep clinic with severe sleep apnea (OSA) (apnea-hypopnea index [AHI] 62) and excessive somnolence (Epworth Sleepiness Scale score 18/24), was imaged with MRI using the Spatial Modulation of Magnetization tagging sequence awake and asleep to visualize upper airway tissue movement. Awake quiet breathing resulted in minimal movement of upper airway tissues. Asleep sequences taken during airway opening post-apnea demonstrated neck extension, mandibular advancement, and widespread tongue deformation accompanying contraction of genioglossus. At the end of the asleep image sequence, the nasopharyngeal airway had a cross-sectional area larger than during quiet breathing awake and there was antero-lateral movement in the lateral walls. In conclusion, the airway responds to apnea by widespread contraction of the genioglossus, followed by mandibular advancement and neck extension. All these maneuvers stabilize and open the airway.