Obstructive sleep apnea (OSA) involves obstruction or reduction of an individual’s airway during sleep and is associated with several comorbidities. Patient evaluation includes detailed history, clinical and radiographic examination, endoscopy, and polysomnography. Management may be nonsurgical or surgical, and Phase II of the Stanford Protocol of surgical management involves maxillomandibular advancement (MMA). Surgical considerations (eg, degree of movement, timing of surgery) and potential complications specific to MMA are discussed in this review. With adequate planning and communication with the patient, MMA is effective in treating OSA, as measured with objective and subjective measures.
Key points
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Obstructive sleep apnea (OSA) is associated with comorbidities and consequences of the individual and society, and patient evaluation includes history, clinical and radiographic examination, endoscopy, and polysomnography.
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Phase II of the Stanford Protocol of surgical management involves orthognathic surgery in the form of maxillomandibular advancement (MMA).
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The surgery-first approach, adequate advancement, counterclockwise rotation, segmental surgery, or distraction osteogenesis may be beneficial in maximizing the potential of MMA.
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With good planning, MMA is effective in treating OSA, as measured with objective and subjective measures.
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Potential complications include velopharyngeal insufficiency, relapse, unsatisfactory esthetic outcomes, and poor outcomes due to the presence of medical comorbidities.
Introduction
Obstructive sleep apnea (OSA) involves obstruction (apnea) or reduction (hypopnea) of an individual’s airway during sleep. OSA is defined as five or more obstructive respiratory events (apneas, hypopneas, or respiratory effort-related arousals) per hour reported on polysomnography (PSG), accompanied with symptoms such as excessive daytime sleepiness, gasping or awakening during sleep, daytime fatigue, or any associated medical disorders. An individual with ≥15 events/h with or without symptoms also fits the criteria of OSA. The apnea–hypopnea index (AHI) measures the number of events of apnea or hypopnea a patient encounters per hour of sleep. The severity of OSA is classified as mild (AHI of 5 to 14), moderate (15 to 29) or severe (≥30).
About 14% of men and 5% of women have an AHI ≥5, with symptoms of daytime sleepiness. This increases with increasing body mass index (BMI), age, male gender, and chronic illnesses such as cardiovascular or cerebrovascular disease and type II diabetes mellitus. ,
An individual with OSA experiences fragmented sleep at night and hypersomnolence and fatigue during the day. They are more susceptible toward impairments in learning, concentration, and social interactions with depression and anxiety. Cardiovascular and cerebrovascular morbidity and mortality increases with the presence and severity of OSA. OSA is a dose-dependent risk factor for hypertension (odds ratio [OR] 2.03 to 2.89). Untreated severe OSA also leads to an increase in the incidence of stroke (hazard ratio 2.86), fatal and nonfatal cardiovascular events (OR 2.87 and 3.17, respectively), atrial fibrillation (OR 2.18), and type II diabetes mellitus (OR 2.30). In addition, patients have an increased risk of perioperative complications, including difficult airway intubations, respiratory depression, and longer inpatient stays.
Clinical Evaluation
Evaluation of a patient with suspected OSA begins with a detailed sleep history, for example, snoring, gasping, choking, witnessed apneas, excessive sleepiness, total amount of sleep, nocturia, headaches, sleep fragmentation, and decreased concentration or memory. An evaluation of potential or reported comorbidities and risk factors should also be documented.
The Epworth Sleepiness Scale (ESS), Berlin Questionnaire, STOP-BANG scoring, and OSA-50 questionnaire are questionnaires that aid in determining a patient’s OSA risk, but should not be used alone to diagnose OSA.
Patients are evaluated for obesity using BMI, large neck circumference (>16 to 17 inches), craniofacial (eg, retrognathia), and nasal abnormalities (eg, turbinate hypertrophy, septal deviation). The oral cavity is examined for increased incisal overjet, a narrow high-arched palate, and macroglossia. Patients with upper airway narrowing may present with an enlarged uvula or soft palate, narrow lateral pharyngeal wall, or tonsillar hypertrophy. The Mallampati and Friedman tongue position scores may aid evaluation of a crowded airway.
Imaging is useful in the evaluation of a patient’s airway. Lateral cephalometry evaluates skeletal discrepancies, posterior airway space (PAS), soft palate length, or an inferiorly positioned hyoid. Computed tomography allows good soft tissue contrast, precise measurements of cross-sectional airway areas, and three-dimensional reconstruction, whereas magnetic resonance imaging provides dynamic airway evaluation and detailed evaluation of various types of soft tissues without radiation exposure.
Nasoendoscopy allows direct visualization of the mechanism of snoring and the site of airway obstruction. Drug-induced sleep endoscopy (DISE) is shown to predict if a patient responds positively to upper airway surgery—nonresponders showed a higher frequency of circumferential collapse at the velum and antero-posterior collapse at the tongue base or epiglottis.
The home sleep apnea test has recently been introduced as a simpler alternative to diagnose OSA in “less complicated” individuals. Sleep study with PSG, however, remains the gold standard for diagnosis of OSA.
Treatment
Nonsurgical management for OSA includes weight loss, continuous positive airway pressure (CPAP) therapy, and mandibular advancement devices. However, these strategies have limitations. Weight loss is challenging for patients with OSA, whereas CPAP requires good patient compliance as patients may not tolerate the side effects (eg, mask discomfort, rhinorrhea, dry mouth, nasal congestion, aerophagia, and conjunctivitis) and more than 50% eventually refuse CPAP. Mandibular advancement devices too have adverse effects such as sialorrhea, temporomandibular joint pain, tooth discomfort, and malocclusion.
Surgical management of OSA aims to correct or reduce anatomic factors that contribute to airway obstruction. The Stanford Protocol is a guideline for the surgical assessment and management of the patient with OSA ( Fig. 1 ).
The extent of surgery depends on the severity and location of airway obstruction. Nasal surgeries aid in eliminating nasal passage obstructions that result in patients breathing through their mouth when sleeping and their tongue subsequently falling posteriorly to obstruct the airway. Tongue or palate surgeries reduce airway obstruction caused by anatomic variations in their respective sites of the pharynx.
Maxillomandibular Advancement
Maxillomandibular advancement (MMA) incorporates the surgical techniques used for orthognathic surgery. Maxillary advancement with a Le Fort I osteotomy moves the hard and soft palates and velopharyngeal muscles anteriorly to open the airway. With a ramus osteotomy, mandibular advancement especially combined with genioplasty advancement, pulls forward the tongue and suprahyoid muscles. Adjunctive procedures (eg, septoplasty, hard palate advancement) can be done concurrently to remove other potential sources of airway obstruction.
In the original Stanford Protocol, MMA was considered Phase II surgery; only patients in whom OSA failed to improve after Phase I surgery would be considered for MMA. The investigators have proven the immense success of MMA without Phase I surgery first. In response, the 2019 guideline expanded the indications for Phase II surgery without Phase I to include:
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Patients with OSA having dentofacial deformities or other indications for orthognathic surgery
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Moderate to severe patients with OSA having anatomic findings that Phase I surgery would not result in significant improvement:
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Complete lateral pharyngeal wall collapse on DISE
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Low hyoid position and obtuse cervicomental angle
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High occlusal plane inclination
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Surgical considerations
The surgical considerations for orthognathic surgery for skeletal discrepancies are well-documented and are applicable for the management of OSA. However, accompanying comorbidities and airway-related considerations warrant specific considerations for MMA, which are discussed below.
Timing of Surgery
Patients with OSA may benefit from a surgery-first or surgery-early approach (SFA). The conventional approach of orthodontic decompensation before MMA may provide a more optimal postsurgical occlusion. However, this increases the duration for resolution of OSA symptoms and may even transiently aggravate them. Patients may thus still require CPAP therapy while undergoing presurgical orthodontics.
SFA, on the other hand, promptly attenuates apnea-related symptoms and comorbid diseases by expanding the airway and correcting any skeletal discrepancies. The regional acceleratory phenomenon allows more efficient postsurgical orthodontic movement that reduces overall treatment time. Hence, patient satisfaction rates are high. An SFA may even be indicated if the postoperative occlusion is reasonable and stable, and if the patient does not want or cannot afford orthodontics.
Potential concerns regarding SFA include the need for greater surgical movements, as well as postsurgical instability, although its influence on relapse is not well studied. Nonetheless, with good patient selection, judicious collaboration, and precise planning, predictable good outcomes from SFA may soon be the norm.
Degree of Movement
Strong evidence is lacking regarding a minimum amount of maxillary or mandibular advancement for optimal treatment outcomes. A mandibular advancement of 10 mm is commonly advocated. However, a systematic review and meta-analysis by Holty and Guilleminault found that a greater degree of maxillary (9.5 mm) instead of mandibular advancement was associated with surgical success in patients with OSA.
Counterclockwise Rotation
Counterclockwise rotation (CCWR) of the maxillomandibular complex provides both functional and esthetic advantages for management of OSA. , CCWR maximizes the advancement of the base of tongue and suprahyoid muscles and brings the soft palate downward and forward. Mehra and colleagues reported a significant increase in the PAS in lateral cephalometric radiographs at these regions when CCWR was performed. CCWR also normalizes the facial profile of patients with high mandibular plane angles and can be a stable procedure when executed judiciously. ,
Future prospective clinical trials are still required to ascertain the degree of rotation required, and whether it results in greater surgical cure or success when compared with MMA alone in patients with OSA.
Segmental Surgery
Modifications to the conventional Le Fort I and ramus osteotomies via segmental surgeries are useful in some instances , :
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Coordination of the dental arches
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Expansion of a narrow maxillary arch with a maxillary midline split
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Esthetic considerations
Large advancements may result an elevated nasal tip or fullness of the cheeks and paranasal regions, leading to an unesthetic bimaxillary protrusive or “simian” appearance. This is especially of concern in patients with a normal sagittal profile or preexisting bimaxillary protrusion, such as in oriental populations. In these patients, anterior segmental osteotomies may be considered for retraction of the anterior segments to prevent this profile change ( Fig. 2 ). In situations where previous extractions have been performed, we need to balance maximal advancement and facial appearance, making use of methods such as CCWR and maxillary impaction ( Fig. 3 ).
However, one must take into consideration the potential complications of segmental surgery. Patients with OSA having medical comorbidities may not be able to tolerate the increased physiologic burden caused by the increased duration of surgery. Segmental surgery also increases the potential risk for damage to the adjacent teeth as well as ischemia of a multi-segmented jaw.
Genioplasty Advancement
Genioplasty advancement moves the genial tubercle, genioglossus, and geniohyoid muscles forward to enlarge the retroglossal space and may be considered in patients with base of tongue obstructions. Genioplasty alone was reported to result in a 67.8% of reduction in AHI. In combination with MMA, this gives greater advancement of the genial tubercle. This is also beneficial esthetically in patients with a retruded or small chin.
Distraction osteogenesis
In addition to conventional orthognathic surgery, distraction osteogenesis may also be considered for the management of OSA especially if larger advancements are needed ( Fig. 4 ). Tables 1 and 2 provide a comparison between conventional orthognathic surgery versus mandibular distraction osteogenesis and maxillary transverse expansion with distraction osteogenesis, respectively.
| Mandibular Distraction Osteogenesis | Bilateral Sagittal Split Osteotomy |
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| Average distraction distance: 12–29 mm | Advocated advancement: 10 mm |
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