(18) Three-dimensional Airway Changes and AHI Reduction Following Maxillomandibular Advancement and Genioglossus Advancement in Patients with Obstructive Sleep Apnea

Abstract:

Background: Obstructive sleep apnea (OSA) is a common disorder characterized by repeated airway obstruction throughout the night. Sequela of untreated and long standing OSA includes increase in all-cause mortality, cardiovascular disease, such pulmonary/systemic hypertension or cardiac arrhythmias, cerebrovascular events, cognitive impairment, diabetes, and overall decrease in quality of life. Therefore, treatment is strongly recommended. Maxillomandibular advancement (MMA) and genioglossus advancement (GA) have been shown to improve or eliminate OSA, as it leads to an increase in posterior airway volume and, therefore, decreased airway collapsibility. However, the exact volumetric changes in airway size are not well documented and therefore correlation between volumetric changes and apnea-hypopnea index (AHI) are not well reported.

Objective: The primary objective is to evaluate the increase in volume in the posterior airway of patients with moderate to severe OSA. The secondary objective is to determine if the increase in airway volume correlates with reduction in AHI. The overall goal is providing insight into the benefit that MMA and GA can offer for patients’ airway volume and reduction in post-operative AHI, allowing for better pre-operative guidance at time of initial consultation.

Materials and methods: Patients were identified and consented pre-operatively and underwent cone-beam computed tomography (CBCT) along with documentation of either a polysomnogram (PSG) or home sleep test (HST). Patients underwent repeat CBCT post-operatively and then a repeat PSG or HST at 6 months. The pre-operative and post-operative imaging were reviewed, and posterior airway volume and area were examined and recorded. The airway volume and area were measured from the superior border of the nasopharynx to the inferior border of the oropharynx ending just above the epiglottis both on pre-operative and post-operative imaging.

Methods of data analysis: The current sample size for the preliminary data is six patients. Current participants were all male, identified as White/Caucasian, ranged in age from 27 to 58 years old, and ranged in body mass index (BMI) from 29.3 to 39.1. Study is currently in active enrollment with the goal of enrolling a total of 21 participants. The study duration is six months. The statistical methods used were paired t-test, Pearson correlation coefficient.

Outcome Data: The preliminary results revealed a Pearson correlation coefficient (r) of -0.543. The paired t-test showed a p-value of 0.0014 with a 95% Confidence interval, -76.926, -32.907. The current study data noted an average of three-unit reduction in AHI per cubic centimeter of increased airway volume.

Results: MMA surgery dramatically increases posterior airway space, which results in a statistically significant decrease in AHI. There is a statistically significant negative correlation between pre-operative AHI and noted benefit.

Conclusions: Based on preliminary results, the higher the pre-operative AHI, the more significant the change in airway volume and AHI reduction post-operatively. There may be a predictable reduction of three units in AHI for every one cubic centimeter increase in airway volume. This may allow for better predictability of results of pursuing MMA/GA, which can be relayed to patients at time of initial consultation.

References:
- US Preventive Services Task Force, Bibbins-Domingo K, Grossman DC, et al. Screening for Obstructive Sleep Apnea in Adults: US Preventive Services Task Force Recommendation Statement. JAMA. 2017;317(4):407-414. doi:10.1001/jama.2016.20325
- Camacho M, Noller MW, Del Do M, et al. Long-term Results for Maxillomandibular Advancement to Treat Obstructive Sleep Apnea: A Meta-analysis. Otolaryngol Head Neck Surg. 2019;160(4):580-593. doi:10.1177/0194599818815158

Figure 1: Scatter plot of AHI reduction in relation to increase in airway volume. Pearson correlation coefficient (r): -0.543.
Figure 2: Sagittal cut of CBCT taken for pre-operative surgical planning with the measured airway boundaries highlighted.

Figure 3: Volumetric reconstruction of measured airway highlighted in Figure 2.