Maxillomandibular Advancement Surgery for Patients Who Are Refractory to CPAP: A Preliminary Report

Purpose:

This pilot study was conducted to determine the effectiveness of maxillomandibular advancement(MMA) in the treatment of patients with moderate to severe obstructive sleep apnea. We also investigated the predictive value of clinical, radiographic, and treatment related variables on the success or failure of maxillomandibular advancement as a treatment for obstructive sleep apnea.  

Patients and Methods:

The study sample included patients who presented to the University of Michigan refractory to CPAP clinic for treatment alternatives. We included patients with moderate to severe obstructive sleep apnea (AHI > 15) who underwent MMA with or without adjunctive procedures such as genioglossus advancement and uvulectomy. Patients who had predominant central apnea(s) or those with inadequate post-surgical data were excluded. Data collected from the patient’s chart review included clinical exam findings, nasopharyngoscopy, CBCT, and polysomnogram. The primary outcome variables were the AHI, minimal oxygen saturation (min SpO₂), and percent time spent with oxygen saturation below 88% as measured on a polysomnogram preoperatively and 3-9 month postoperatively. The patient variables included in the study were age, BMI, neck circumference, relative tongue size, pre-op airway dimensions, change in airway dimensions, soft palate length, size of the advancement, and occlusal plane changes.

Statistical Analysis:

Descriptive statistics and ANOVA analysis were used to establish a correlation between the primary outcome variable (AHI) and patient variables.

Results:

Seventeen patients met the inclusion criteria for the study including 13 males and 4 females with a mean age of 47.9 (20–62) years old. The mean BMI was 31.9 (21.6-38.7) preop and 28.2 (19.2-37) postop. The mean advancement at B point was 13.4 mm (2.85 mm) and at A point 10.2 mm (1.64 mm). The mean preop AHI and min SpO₂ were 48.8 (18–82.5) and 78% (60–91%) respectively, and the mean postop AHI and SpO₂ were 14.9 (1.9-45.1) and 85.4% (70-95%) respectively. The percentage time spent with a SpO2 below 88% was a mean of 12.9% preop and 1.19% postop. Nine out of 17 patients achieved an AHI<10, for a relative cure rate of 52.9%. Among the 8 patients with AHI>10, three had significant central apneas (CAI>5) and one patient had no obstructive but only central events with a central apnea index of 30.1 (AHI 31.9). One patient was a non- responder (AHI 44.7 to 45.1). Compared to the successful group, the unsuccessful group was older (mean 53.4 vs 43.1), had a higher preop AHI (54.2 vs 44), had a higher postop BMI (31.6 vs 28.1), had significant postop central apneas in 50% (4/8) of patients, and had a higher incidence of macroglossia (88% vs 67%).  The unsuccessful group had higher preoperative airway volume (12.9 cm3 vs 11.9cm3) and higher preoperative minimum axial area (71.7mm2 vs 60.1mm2). Postoperatively both groups had similar airway volumes of 26.3 cm3 in unsuccessful and 25.5 cm3 in successful groups. However the successful group had higher minimum axial area (288.4 mm2 vs 263.9 mm2)    

Conclusions:

In this preliminary study, a sample of OSA patients underwent MMA with a mean 69% reduction in AHI. Based on a surgical success criteria of an AHI decrease by 50% or AHI <20, and after accounting for central apneas, 15/17 patients or 88% achieved a successful result with MMA (+/- adjunctive procedures) in this study. However, only 52.9% of patients achieved relative resolution of OSA (AHI <10). Further analysis with a larger sample size is needed to determine predictive variables for optimal patient selection. Since obstructive sleep apnea is a multifactorial condition, factors such as low neuromuscular tone during sleep, selective fat deposition in the tongue and parapharyngeal fat pads, medication use, diet and lifestyle may help explain cases with suboptimal response to treatment.