Upper Airway Stimulation in Patients with Obstructive Sleep Apnea Undergoing Maxillomandibular Advancement
PURPOSE:
Maxillomandibular Advancement (MMA) is the most effective procedure for patients with moderate to severe obstructive sleep apnea (OSA). In the literature it is reported to advance the maxillomandibular complex 8-10 mm. Some patients might not get total relief of upper airway obstruction while others might fear the bi-maxillary facial-skeletal appearance created by MMA. The morphology of upper airway with normal reference values of total volume and surface area at choke points have been described in the literature. Here in we evaluate and describe an upper airway simulation module added to the 3dMDvaltus software(Atlanta, Georgia) for upper airway analysis. The upper airway simulation module can assist in the pre-operative planning and determining the extent of advancement needed to relief of upper airway obstruction.
MATERIAL AND METHODS:
Six patients, 5 male and 1 female, with moderate to severe OSA diagnosed with overnight polysomnogram and clinical examination underwent MMA. Patients had pre and post operative Cone Beam Computerized Tomography scan with upper airway analysis with 3dMDvultus software. All patients had a resolution of their OSA verified by overnight polysomnogram and clinical symptoms. Post surgery a separate Virtual Treatment Objectives (VTO) with upper airway simulations performed on the new version of 3dMDvultus software on all patients and the surgical movements were replicated. The total volume of upper airway space, retro-palatal space, retro-glossal space measured for pre-surgical, simulated and post-surgical. The surface area of the choke points at the retro-glossal and retro-palatal with the transverse and anterior-posterior diameters of the upper airway measured for pre-surgical, simulated and post-surgical. The recorded data evaluated and analyzed.
RESULTS;
The simulated upper airway total volume and surface area at the choke points with transverse and anterior-posterior diameters were compared to the known post operative airway measurements and the close proximity of the values calculated in average percentage. The total volume of the simulated upper airway came as close as 94% of the post operative value. The volume of the upper airway at the retro-palatal space came as close as 81% and the retro-glossal space at 80%. The surface area at the retro-palatal choke point came as close as 72%, the transverse dimension at 92% and the anterior-posterior dimension at 62%. The surface area at the retro-glossal choke point came as close as 76%, the transverse dimension at 78% and the anterior-posterior dimension at 72%.
CONCLUSION;
The upper airway simulation module can be a great adjunct to upper airway analysis and VTO in pre-operative planning for patients with OSA undergoing MMA. The upper airway simulation module can assist in planning the extent of surgical movements needed to alleviate upper airway obstruction and avoid function and form pitfalls of MMA. This is the first attempt at simulating the upper airway and an excellent starting point to make further modification to improve predication.
REFFERENCE;
1. Schendel SA, et al. Airway growth and development: A computerized 3-dimensional analysis. J Oral & Maxillofac Surg 2012 , Feb. 9 [Epub ahead of print].
2. Schendel SA et al. Maxillary, Mandibular and chin advancement: Treatment planning based on airway anatomy in obstructive sleep apnea. J Oral Maxillofac Surg 69:3, 2011