Morphometric Analysis of Swallowing Mechanics after Surgery for Obstructive Sleep Apnea

Abstract

Objectives: Apply a new method of analyzing swallowing biomechanics on postoperative obstructive sleep apnea (OSA) patients using parameters of the modified barium swallow (MBS) imaging. Methods: This novel biometric analysis involved two patients following uvulopalatopharyngoplasty, relocation pharyngoplasty, and base of tongue resection for OSA. Postoperative MBS indicated mild swallowing impairment in both patients. Coordinates mapping 10 anatomical landmarks were collected from every frame of the oropharyngeal swallow using ImageJ software. A canonical variate analysis was performed using MorphoJ software with data pooled by subject (S1, S2) and swallowing phase (OP = oral phase, PP = pharyngeal phase). The Mahalobonis distances (D) of the pooled means from each group were defined. Eigenvectors of shape change in these patients were compared to previously published subjects (non-surgical) to document changes in swallowing mechanics. Results: Significant differences in shape change were found for all values: OP versus PP of S1(D = 9.2, P < .0001) and S2 (D = 10.7, P < .0001); OP of S1 versus S2 (D = 45.4, P < .0001); PP of S1 versus S2 (D = 39.2, P < .0001). Eigenvectors indicated reduced pharyngeal shortening and reduced tongue base retraction compared to published data of normal subjects. Conclusions: Tongue base retraction and reduced pharyngeal shortening was noted in this small cohort of patients. These observations are consistent with the postoperative goal of necessary tightening in these areas to avoid collapse. Future controlled studies should be performed to determine whether these changes in swallowing mechanics are specific to surgical interventions or the underlying morphology of OSA patients. This method could potentially be used to quantify the effectiveness of sleep surgical techniques.