The effect of maxillomandibular advancement on the pharyngeal airway and apnea-hypopnea index in obstructive sleep apnea syndrome patients

Abstract

Problem: Maxillomandibular advancement (MMA) surgery has demonstrated good success for the treatment of obstructive sleep apnea syndrome (OSAS). MMA has been shown to increase the pharyngeal airway space postoperatively. This is thought to be one of the reasons for the decrease in apnea-hypopnea index (AHI) found during postoperative polysomnographic studies. The purpose of this study is to determine if there is a correlation between the increase in pharyngeal airway space and decrease in AHI. Methods: Charts were reviewed for OSAS patients who received MMA surgery between October 1996 and April 2002. The inclusion criteria were: 1) completion of a polysomnographic study before and a minimum of 6 months following surgery, 2) a standardized lateral cephalometric radiograph taken before and within 48 hours postoperatively, 3) a preoperative AHI greater than 10. The outline of the posterior pharyngeal wall, soft palate and base of tongue were traced preand postoperatively. The minimum perpendicular distance between the posterior pharyngeal wall and both the soft palate and base of tongue were measured. The airway measurements as well as the AHI were analyzed using the Wilcoxon signed rank test for significance between the pre and postoperative values. Changes in pharyngeal airway space and AHI were analyzed using the Spearman Rank Order Correlation Test. Results: A total of 48 patients received MMA surgery as treatment for OSAS during this time period with 20 satisfying the requirements (18 male and 2 female). The average age was 44 years (range of 34 to 61). Twelve patients had MMA, 7 patients had MMA in conjunction with genioplasty and 1 patient had maxillary advancement with a unilateral sagittal split osteotomy. The median increase in distance between the posterior pharyngeal wall and soft palate was 96% (maximum 325%, minimum 14%; first quartile 64%, third quartile 96%). The median increase in distance between the posterior pharyngeal wall and base of tongue was 108% (maximum 500%, minimum 0%; first quartile 73%, third quartile 157%). The median decrease in AHI was 78% (maximum 100%, minimum 23%; first quartile 52%, third quartile 98%). The Spearman Rank Order Correlation test was calculated and revealed no correlation between the increase in pharyngeal airway and decrease in AHI. Conclusions: Treatment of OSAS using MMA surgery resulted in an average decrease in AHI of 73% for this patient population. There was no correlation found between the increase in posterior pharyngeal airway space and the decrease in AHI postoperatively.