INTER-PTERYGOID DISTANCE AS A PREDICTOR OF SUCCESS IN MODIFIED EXPANSION SPHINCTER PHARYNGOPLASTY

Introduction Modified expansion sphincter pharyngoplasty (MESP) is a novel surgical technique designed to improve both retro-palatal collapse and lateral pharyngeal wall stability in OSAS patients. Although no plane indications for this procedure have been reported in the literature, the current main indications are retro-palatal obstruction and lateral pharyngeal collapse pattern. Objective The aim of the study was to identify possible clinical indicators of post-operative success. Methods Data of patients undergoing MESP at our institution were collected prospectively during the period february 2009 – October 2011 and included clinical features, sleep endoscopy features, Cephalometric measures, CT scan measures, pre and postoperative polysomnographic data. Success was defined as RDI<15 in patients without co-morbidity and RDI<5 in patients with co-morbidity. Univariate analysis was conducted to identify possible predictors of success. Pearson correlation between continuous clinical variables and reduction of the preoperative RDI were explored as well. Results 39 patients underwent MESP alone and 30 patients MESP plus hyoid suspension. Total success rate was 65.8% (patients not requiring CPAP). No single predictor of success resulted from univariate analysis. Pre-operative RDI (p<0.001), pre-operative supine AHI (p=0.001), tonsil grade (p=0.001) and inter-pterygoid distance measured on CT scan (p=0.008) showed a significant direct correlation with the post-operative RDI improvement. Age showed a significant inverse correlation with RDI improvement (p=0.038). Interestingly, inter-pterygoid distance maintained a significant correlation with RDI improvement when controlled for hyoid suspension, tonsil grade, age, supine AHI and preoperative RDI. Conclusions No significant predictors of success were identified. However, several variables appear significantly correlated to the postoperative RDI improvement. Among these, inter-pterygoid distance measured on CT scan is a promising lateral anatomical parameter not commonly assessed in the routine diagnostic workup, that may be included in the selection criteria of patients fitting the current clinical indications for MESP. Further study on a wider population is needed to confirm these results and to validate a cut-off value for the clinical practice.