What volumetric changes in upper airway soft tissue structures can be viewed using magnetic resonance imaging (MRI) pre- and post-transoral robotic surgery (TORS)for obstructive sleep apnea (OSA)?
Background: Many OSA patients who have difficulty tolerating continuous positive airway pressure often seek surgical evaluation. TORS allows for direct visualization of, and better access to, the base of the tongue compared to open procedures, but it is unknown why some patients respond and other patients do not. MRI can examine how the upper airway soft tissue volumes change, or do not change, following surgical intervention.
Explore this issue:August 2015
Study design: Prospective, nonrandomized study of 19 MRIs and 18 polysomnograms (PSGs)analyzed pre- and post-operation.
Setting: Department of Otorhinolaryngology–Head and Neck Surgery, Hospital of the University of Pennsylvania, Philadelphia.
Synopsis: The procedure consisted of a bilateral robotic posterior hemiglossectomy with limited pharyngectomy followed by a uvulopalatopharyngoplasty, which was a modification of the expansion sphincteroplasty technique.
Of the 18 patients who completed their post-operative PSG, 11 were surgical successes and 12 were surgical responders. Surgical success patients had a mean apnea-hypopnea index (AHI) decrease of 52.9±29.0 events/hour; nonsuccesses had a decrease of 4.5±33.5 events/hour. Surgical response patients had a mean AHI decrease of 52.1±27.8 events/hour; nonresponders had a mean increase of 2.1±31.3 events/hour. Retropalatal (RP) airway volume decreased by a mean of 28.8±31.1%, while retroglossal (RG) airway volume increased by a mean of 110.4±134.3%.
There was no statistically significant change in retroepiglottic (RE) airway volume, and no significant change in mandibular volume following surgery. There were significant decreases in soft palate volume and RP lateral walls, a significant increase in the RG lateral wall volume, and a suggestive decrease in genioglossus tongue volume. Greater decreases in lateral wall volume correlated with greater decreases in AHI.
Bottom line: Airway, tongue, soft palate, and lateral wall volumes change significantly after OSA-TORS. Volumetric upper airway MRI may be a helpful tool to better understand reasons for surgical success.
Citation: Chiffer RC, Schwab RJ, Keenan BT, Borek RC, Thaler ER. Volumetric MRI analysis pre- and post-transoral robotic surgery for obstructive sleep apnea. Laryngoscope. 2015;125:1988-1995.