Maxillomandibular Advancement as Surgical Treatment for Obstructive Sleep Apnea in Active Duty Military Personnel: A Retrospective Cohort

Transcription

1 MILITARY MEDICINE, 177, 11:1387, 2012 Maxillomandibular Advancement as Surgical Treatment for Obstructive Sleep Apnea in Active Duty Military Personnel: A Retrospective Cohort MAJ Marc M. Serra, DC USA*; MAJ David Greenburg, MC USA ; CPT Megan Barnwell ; COL David Fallah, DC USA ; COL Karen Keith, DC USA*; LTC Vincent Mysliwiec, MC USA ABSTRACT Objective: The objective of our study is to assess the surgical outcomes of active duty military personnel undergoing maxillomandibular advancement (MMA) for the treatment of obstructive sleep apnea. Methods: Pre- and postoperative data on 37 military personnel who underwent MMA were assessed for changes in apnea hypopnea index (AHI) and minimum oxygen saturation. A surgical success was defined as a reduction of AHI by 50% or a postoperative AHI of <20. Results: 83.7% had an AHI greater than 20 (n = 33; range ) with a mean preoperative AHI of 50.5 per hour. The postoperative AHI decreased by 36.3 to a new value of 14.2 (p < 0.001). Most service members experienced a postoperative AHI of less than 20 (n = 28; 76%). Sixteen (43%) had a surgical cure (AHI < 5). The number of surgical successes for this study was 81% (n = 30). The mean minimal nocturnal oxyhemoglobin saturation did not significantly change from preoperative 85% (SD = 6.8%) to postoperative 86% (SD = 7%; p = 0.21). Conclusion: MMA represents a viable surgical treatment option for military personnel in whom continuous positive airway pressure is either not tolerated or for those who desire a fully deployable status. INTRODUCTION Obstructive sleep apnea (OSA) is a common disease affecting 2 to 4% of middle aged adults. 1 It is estimated that 3 million males and 1.5 million females in the United States have OSA. 2 The U.S. Military shows a similar prevalence. Analysis of records from the Veteran s Affairs system revealed that approximately 3% of veterans have OSA. 3 The crude incidence rate of diagnoses from 2000 to 2009 showed a nearly six-fold increase in active duty service members diagnosed with OSA. 3 A study performed at Walter Reed Army Medical Center showed that 72.6% (n = 527) of all patients who underwent a formal sleep study in the year 2000 had OSA. 4 OSA is characterized by the complete or near-complete cessation of airflow during sleep because of the obstruction of the upper airway. Common symptoms of OSA include snoring, choking or gasping during sleep, insomnia, morning headache, and daytime sleepiness. 5 The pathogenesis of OSA is related to transient occlusion of the upper airway during periods of sleep when tonic pharyngeal muscular activity results in collapse of the upper airway. Military personnel with *Oral and Maxillofacial Surgery Department, Madigan Healthcare System, Joint Base Lewis-McChord, 9040 Jackson Avenue, Tacoma, WA Internal Medicine, Madigan Healthcare System, Joint Base Lewis- McChord, 9040 Jackson Avenue, Tacoma, WA Cardiology Department, Brooke Army Medical Center, 3851 Roger Brooke Drive, San Antonio, TX Oral and Maxillofacial Surgery Department, William Beaumont Army Medical Center, 5005 North Piedras Street, El Paso, TX kpulmonology/critical Care/Sleep Medicine, Madigan Healthcare System, Joint Base Lewis-McChord, 9040 Jackson Avenue, Tacoma, WA The views expressed are those of the author(s) and do not reflect the official policy of the Department of the Army, the Department of Defense, or the U.S. Government. doi: /MILMED-D untreated OSA are at risk for accidents related to excessive daytime somnolence (EDS) and, in severe OSA, increased cardiovascular morbidity and mortality. Patients who are suspected of having OSA are referred for a polysomnogram (PSG) to determine their apnea hypopnea index (AHI). This represents the number of apneas and hypopneas recorded per hour of the study. The patient s OSA severity is based on a standardized grading system 6 (Table I). The current standard therapy for OSA is continuous positive airway pressure (CPAP); yet, many individuals do not tolerate this form of therapy. Often discouraged by the lifelong nightly requirement for CPAP, approximately 15 to 30% of patients refuse this option. 7 Additionally, 20 to 40% will discontinue CPAP after 3 months because of lack of compliance. 8 Military personnel with OSA are treated with CPAP. However, with CPAP therapy, there are specific requirements according to Chapter 5-14 of AR , a U.S. Army Soldier can only be deployed when,...the area of deployment includes the following: availability of a reliable power source, absence of environmental factors that would render electrical equipment inoperable or unreliable, and the availability of power source of replacement supplies. These requirements potentially limit deployability for military personnel diagnosed with OSA. A treatment modality which either cured or minimized the severity of OSA in service members without the inherent requirements of CPAP would be ideal. Soldiers with an AHI less than 30 per hour and effectively treated with CPAP are deployable to most theaters of operation; however, those with severe OSA are not deployable without an extensive waiver process. 9 In a nondeployed environment, there are not significant concerns about CPAP malfunctions as resupply is readily available. For Soldiers with severe OSA, no clinical criteria establish how long they MILITARY MEDICINE, Vol. 177, November

2 TABLE I. Grading of Severity of OSA 6 OSA Severity AHI Normal AHI < 5 Mild 5 < AHI < 15 Moderate 15 < AHI < 30 Severe AHI > 30 can safely go without CPAP. A night or two without CPAP has not been shown to result in an adverse outcome, but resupply for CPAP in a deployed environment can take a prolonged period of time. Thus, an AHI cut-off of 60, twice the upper limit of severe disease, is a frequently used reference to send Soldiers to a medical evaluation board or deem them unsafe to deploy to austere environments. OSA can be caused by an obstruction at one or multiple levels of the pharynx. Various surgeries exist for the treatment of OSA depending on the level of obstruction and severity. The current Stanford protocol addresses the approach to patients with OSA who have failed nonsurgical therapy. This protocol targets the level of obstruction in a stepwise approach. Phase I of this protocol targets the retropalatal and retrolingual area. 10 Phase II directs the patient to maxillomandibular advancement (MMA). 11 There are surgeries that specifically address the redundant soft tissues in the parapharyngeal areas that are causing the obstruction. Adenoidectomy, functional septorhinoplasty, turbinoplasty, various modifications of the uvulopalatopharyngoplasty, base of tongue ablation, and hyoid suspensions are surgeries designed to decrease the amount of soft tissue redundancy in the nose, oral pharynx, and hypopharynx. 12,13 These procedures are helpful in select patients with generally one level of obstruction but are not indicated for patients with severe OSA, which is the type of patient that we are focusing on in this study. Uvulopalatopharyngoplasty has a long-term surgical response of 40.7% in select patients; thus, the majority of patients will still have residual OSA despite having undergone a surgical intervention. 14 In contrast to the above surgeries, MMA addresses all levels of obstruction of the pharynx. It has reported success rates of 95, 15 96, 16 and 98%. 17 Long-term success rates for OSA treated with MMA reported in the literature since 1995 range from 75 to 100%. 18 MMA is reported as a surgical cure for OSA by increasing the volume of the upper airway. The goal of MMA surgery is to move the maxilla and the mandible forward (anteriorly). When the bone and attached soft tissues are advanced, the airway of the nasopharynx, oropharynx, and hypopharynx increase in the anterior posterior and in the transverse dimensions. A recent study of reconstructed computed tomography cone beam volumetric analysis of the upper airway, pre- and post-mma, shows dramatic increases in airway volume. 19 Based on the marked changes in the upper airway, where obstruction occurs, and multiple prior studies showing significant improvement in the AHI, MMA has the best chance of curing OSA, resulting in a fully deployable service member. The aim of our study was to assess surgical outcomes of active duty military personnel undergoing MMA for the treatment of OSA. To our knowledge, MMA and its surgical outcomes have not previously been reported in an active duty population. PATIENTS AND METHODS The study was a retrospective review of all MMA procedures performed at our institution on active duty military personnel between January 1, 2006 and December 31, 2009 for the treatment of OSA. Our study was performed under an approved protocol by the Madigan Healthcare System Institutional Review Board. All patients had their surgery and preoperative and postoperative PSGs performed at Madigan Healthcare System, Tacoma, Washington. Madigan is an Army tertiary referral hospital that covers the Western Regional Medical Command. We identified 37 service members (36 males and 1 female) for inclusion into the study. The mean age was 35 (range 21 50) years old, and the mean AHI was 50.5 per hour. Figure 1 shows the distribution of patients among the three classifications of OSA. As our study was not performed in accordance with a prospective protocol, the selection criteria were not standardized. A general approach to MMA at out institution is to fabricate an acrylic splint achieving a 10-mm advancement, as well as one achieving an 8-mm advancement of the maxilla, should the greater distance be unattainable because of soft tissue restriction. A standard intraoral LeFort I osteotomy is performed with attention to the piriform rims and anterior nasal spine to minimize potential unaesthetic soft tissue changes to nasal tip projection. The acrylic splint is used to set the maxilla, then 2.0-mm titanium plates and screws are placed bilaterally at the piriform rims and zygomatic buttresses. Allogeneic bone grafting augments and supports any excessive bony gaps after the advancement. Once the maxilla is set, the mandible is advanced using a standard bilateral sagittal split osteotomy. The distal segment is fixated to the proximal using a minimum of three bicortical 2.0 titanium screws via a transcutaneous technique. Because of the degree of advancement, the final splint usually remains in place with guiding elastics for at FIGURE 1. Stratification of patients vs. preoperative OSA classification MILITARY MEDICINE, Vol. 177, November 2012

3 FIGURE 2. Pre- and postoperative AHI comparison. X-axis represents patient number. Y-axis represents pre- or postoperative AHI. least 2 weeks. To address the hypopharyngeal soft tissue obstruction, a sliding horizontal mandibular osteotomy or a genial tubercle advancement osteotomy, of the maximum distance allowed by the thickness of the cortex, is performed and secured with 2.0-mm screws and plates. This is all performed under general anesthesia and then the patient is transferred to the intensive care unit for postoperative observation and pain control. The outcome variables of postoperative AHI and minimal nocturnal oxyhemoglobin saturation were assessed. Surgical success was defined as a 50% reduction or a postoperative AHI of less than 20 per hour, consistent with previous published comparative studies. 17 PSGs at our institution are scored according to the alternative method of scoring obstructive events set forth by the American Academy of Sleep Medicine. 20 RESULTS The overall success rate for MMA in this study, as defined by our criteria, was 81% (n = 30; range 0 46). 83.7% of service members had a preoperative AHI greater than 20 (n = 33; range ). The mean preoperative AHI was 50.5 per hour, and the mean postoperative AHI was 14.2 (p < 0.001). The postoperative AHI dropped by Most experienced a reduction to at least 20 in their AHI (n = 28; 76%). Sixteen patients (43%) had an AHI of <5 resulting in no residual disease or a surgical cure. Two patients had an increase in their postoperative AHI. (Fig. 2) The mean minimal nocturnal oxyhemoglobin saturation did not significantly change from preoperative 85% (SD = 6.8%) to postoperative 86% (SD = 7%; p = 0.21). Our data did not show a correlation between AHI and minimal nocturnal oxyhemoglobin saturation (Fig. 3). FIGURE 3. MMA effect on minimal oxyhemoglobin saturation. X-axis represents patient number. Y-axis represents pre- or postoperative minimal record oxyhemoglobin saturation. MILITARY MEDICINE, Vol. 177, November

4 DISCUSSION OSA is linked to an increased risk of motor vehicle accidents, neurocognitive impairment, and cardiovascular disease. 3,21,22 EDS, one of the cardinal manifestations of untreated OSA, results in delayed thought, concentration, and reaction time. 23 When this is combined with a military that demands their personnel to make life or death decisions and maintain a high level of alertness, it is obvious to understand the need for a comprehensive medical assessment and treatment plan for military personnel with OSA. The increase in military personnel diagnosed with OSA has occurred concomitantly with a rise in medical encounters coded for overweight/obesity. 3 The major risk factor for OSA is obesity. 24,25 An optimal treatment plan for military personnel would include addressing weight loss in those who are obese as weight loss, as little as 10 pounds, can improve the severity of OSA, and otherwise result in a more fit warrior. 24 The goal of this study is to suggest a new treatment protocol for military personnel with severe OSA. Current literature and our study show that MMA is a successful treatment for military personnel with severe sleep apnea. This one surgery would not only allow the patient to be useful to the military by being deployable without the need for CPAP, but it would increase the long-term health of its fighting force who are currently suffering from OSA. OSA has a significant public health impact because of its co-occurrence with other health-related conditions. Hypertension, cardiovascular dysrhythmias, stroke, myocardial infractions, depression, as well as accidents from EDS can result from the prolonged pathophysiology of OSA. 5 MMA would result in a significant reduction in OSA-related health risks and could represent a considerable financial savings on the health care system. 26 The one-time cost of early MMA is potentially less expensive than multiple less predictable operations and hospital stays. In addition, a lifetime of CPAP with its associated costs of repeat sleep studies, registrations, equipment maintenance and replacement, technical support, and compliance counseling may be less cost beneficial than one-time MMA surgery. 26 The current standard of therapy for OSA is CPAP with compliance defined by wearing CPAP greater than 4 hours nightly on 50% of nights. Although while wearing CPAP, the patient s AHI is usually <5, when noncompliant, the AHI is the same as the preinterventional AHI, and thus untreated OSA. The resultant mean AHI can be much higher than 5 with CPAP therapy and still be considered successful. 27 These implications are magnified in military personnel as their compliance with CPAP can be affected by multiple issues to include nasal congestion, mask issues, airway dryness, lack of reliable electricity, and austere sleeping environments. This suggests that although the MMA postoperative AHI may be higher than 5, it may be a better health benefit since it is consistent every night vs. an AHI of less than five for the 4 hours that the patient wore the device for half of the week. There is currently a lack of high-level controlled studies in the surgical literature and an absence of standardized criteria to define surgical success for the treatment of OSA with MMA. 28 This has limited the widespread usage of surgery to treat OSA. Yet, in appropriately selected patients, who undergo MMA, their AHI is known and does not have the potential variability which can occur in patients who are not 100% compliant with their CPAP. Nine previous studies with a total of 234 subjects showed an overall reduction in AHI of 87% with MMA 13 (Fig. 4). Our data further support the potential of MMA for the definitive treatment of military FIGURE 4. Medicine. 26 Mean pre-ahi vs. post-ahi comparison study. Reprinted with permission from Sharon Tracy, PhD, American Academy of Sleep 1390 MILITARY MEDICINE, Vol. 177, November 2012

5 personnel with moderate to severe OSA. Our surgical cure rate was slightly lower than the other reported studies. This may be due to a number of factors including a nonselect group of patients and the lack of standardized selection criteria. MMA is effective treatment of OSA but not without surgical risk. The LeFort procedure can permanently injure the palatine arteries and the infraorbital nerve that gives feeling to the skin of the face and the upper lip. In addition, there is the risk of possible damage to the roots of the teeth in the area of the osteotomy. 29 The greatest risk of a bilateral sagittal split osteotomy for the advancement of the mandible is permanent damage to the inferior alveolar neurovascular bundle, with subsequent loss of feeling to the lower teeth, lip, and chin. There is also the risk of an unfavorable fracture that would require additional plating or maxillomandibular fixation for approximately 6 weeks. 30 Positive and negative esthetic changes may occur with this surgery. 31 A 2000 study revealed patient satisfaction is extremely high after MMA. Furthermore, previous concerns of unfavorable postoperative facial esthetics do not appear to be significant. 32 In contrast to this study, it has been observed that many do not esthetically tolerate such a large advancement of the facial skeleton, and attention to patient selection and preoperative counseling is paramount. CONCLUSIONS In our retrospective review of nonselected active duty military personnel undergoing MMA, 81% of patients experienced a significant reduction in their AHI and 43% had a surgical cure with no residual OSA. Larger, multicenter studies utilizing a standardized surgical protocol, with uniform, validated selection criteria and pre- and postoperative assessments are required. MMA has the potential to cure military personnel with moderate to severe OSA and render them fully deployable to all theaters of operation. A protocolized approach to the surgical evaluation, management, and follow-up of military personnel with OSA could result in improved outcomes in future studies. REFERENCES 1. Neruntarat C: Genioglossus advancement and hyoid myotomy: shortterm and long-term results. J Laryngol Otol 2003; 117(6): Kryger MH: Diagnosis and management of sleep apnea syndrome. Clin Cornerstone 2000; 2(5): Armed Forces Health Surveillance Center: Obstructive sleep apnea, active component, U.S. Armed Forces, January 2000 December MSMR 2010; Kristo DA, Lettieri CJ, Andrada T, Taylor Y, Eliasson AH: Silent upper airway resistance syndrome: prevalence in a mixed military population. 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