I got my answer. Or four possible answers via a supine MRI…
The anatomy:
• Bilateral sublingual gland hypertrophy — enlarged glands under the tongue on both sides, narrowing the airway and pushing the epiglottis posteriorly
• Retropalatal AP diameter: 5mm (normal is ~11–14mm) — severe narrowing at the soft palate level
• Retroglossal AP diameter at lingual tonsil: 5mm — second level of critical narrowing
• Soft palate thickened (12.9mm) with uvula extending 4.3cm below the nasal cavity floor — almost reaching the sublingual glands from above
• Retro-epiglottic space reduced — epiglottis mechanically displaced posteriorly by the sublingual gland mass
So essentially four stacked levels of severe narrowing, with soft tissue encroaching from both above (elongated uvula) and below (hypertrophied sublingual glands), and an epiglottis that’s being pushed into the airway structurally.
The functional consequence:
PAP therapy data across 1,700+ nights shows a consistent “valve-like collapse” pattern — increasing pressure amplifies the obstruction rather than resolving it, because the displaced epiglottis acts as a one-way valve under higher airflow. I identified a pressure ceiling between EPAP 12 and 13 cmH₂O through controlled experiments — above that threshold the obstruction worsens.
I’m currently running on a regular bilevel in S mode, min EPAP of 12.0 and PS of 5.0 with a soft cervical collar but still roughly 22–27 autonomic arousals per hour by pulse oximetry, stable breathing only 10–50% of the night depending on configuration.
I have been on CPAP since 2012 and have really trying to get to the bottom of this earnestly for over four years. On one hand, it is nice to finally know a device alone won’t solve this but it still leaves me with more questions than answers.
Anyone else face something similar?