Stability of Modified Maxillomandibular Advancement Surgery in a Patient With Preadolescent Refractory Obstructive Sleep Apnea Hyo-Won Ahn, PhD,* Baek-Soo Lee, PhD,y Sung-Wan Kim, PhD,z and Su-Jung Kim, PhDx Maxillomandibular advancement (MMA) surgery can be considered a primary single-stage treatment for improving the quality of life in patients with preadolescent refractory obstructive sleep apnea (OSA). The aim of the present report was to evaluate the treatment efficacy and stability of modified MMA surgery in a growing patient with morbidly severe symptoms and medical complications. Using the follow-up results from the questionnaire, polysomnography, 2-dimensional cephalometry, and 3-dimensional conebeam computed tomography measurements, the success of modified MMA surgery was assessed in terms of the postoperative improvements of functions and esthetics and postretentive stability of the improvements throughout the growth period. The present report provides some clinical recommendations when considering skeletal surgery in preadolescent patients with OSA: 1) the decision criteria of MMA surgery as definite treatment; 2) the proper surgical design for both maximum enlargement of the airway and esthetic improvement; and 3) the postoperative facial growth for long-term stability of airway function and skeletal improvement. With a systematic multidisciplinary approach, early surgical intervention can be used to treat OSA in children successfully and permanently. Ó 2015 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 73:1827-1841, 2015
Obstructive sleep apnea (OSA) in children is a common health problem that has been increasing, although the individual symptoms present a challenge to the proper diagnosis.1 The main etiologic factors of pediatric OSA are related to anatomic obstructions such as hypertrophic adenoid or tonsils, parapharyngeal fat deposition, and a retruded small mandible.2 Therefore, the treatment of OSA in children should focus on enlarging the airway space by removal of the hypertrophic soft tissue or by modification of craniofacial growth, thus further preventing the development of the disease and resolving the symptoms.2,3
The medical approaches for treating pediatric OSA include adenotonsillectomy (TA) as the first line of treatment and pharmacologic agents or continuous positive airway pressure therapy as nonsurgical alternatives.4,5 The cure rate of TA has been reported to be up to 80%5; however, this means that postoperative persistence of OSA can be as frequent as 20%. The children with residual OSA after TA might have other causative factors such as nasal obstruction, obesity, or a definite skeletal deformity.4 Therefore, it is imperative to differentially diagnose the basic origin of OSA to select the best treatment for each patient.
*Assistant Professor, Department of Orthodontics, Kyung Hee
Dentistry, 1 Hoegi-Dong, Dongdaemoon-Ku, Seoul 130-701, Korea;
University School of Dentistry, Seoul, Korea.
e-mail: [email protected]
yProfessor, Department of Oral and Maxillofacial Surgery, Kyung
Received December 30 2014
Hee University School of Dentistry, Seoul, Korea. zProfessor, Department of Otorhinolaryngology–Head and Neck
Ó 2015 American Association of Oral and Maxillofacial Surgeons
Surgery, Kyung Hee University School of Medicine, Seoul, Korea.
xAssociate Professor, Department of Orthodontics, Kyung Hee
Accepted February 28 2015
University School of Dentistry, Seoul, Korea. Address correspondence and reprint requests to Dr S.-J. Kim: Department of Orthodontics, Kyung Hee University School of
1828 Orthodontic approaches are indispensable for the collaborative management of children with OSA. In general, growth modification treatment to improve skeletal structures permanently or myofunctional therapy to train the tongue and lips can be applied to increase the airway space. Maxillary expansion with a rapid palatal expander,6-8 maxillary advancement with a face mask,9,10 or mandibular advancement with a functional appliance11 will increase the oral cavity volume to ultimately position the tongue base upward and forward. In children with medically refractory OSA, however, maxillomandibular advancement (MMA) surgery should be considered the primary single-stage treatment to secure quality of life.1,12 The aim of the present report was to evaluate the stability of the modified MMA surgery in a preadolescent patient with morbidly severe OSA using the data from the follow-up questionnaire, polysomnography, 2-dimensional cephalometry, and 3-dimensional cone-beam computed tomography (CBCT) measurements. The decision-making process toward the best treatment option was based on our integrated clinical pathway of orthodontic approaches for treating children with OSA (Fig 1).
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Case Report An 11.1-year-old girl with the chief complaint of difficultly breathing was referred from the ear, nose, and throat department for collaborative treatment of severe OSA. Although at 4 and 7 years old, the patient had undergone TA surgery, she still reported snoring and presented with OSA symptoms, including restless sleep, frequent nightmares, heavy sweating, and excessive daytime sleepiness. She had a serious medical history of pneumonia, asthma attacks, hyperventilation-related dyspnea or tachypnea, pantalgia, stress-induced hand shaking or leg paralysis, arthritis, and auditory and/or visual hallucinations. She was taking a year off from school because of psychosocial problems, including adjustment disorder with anxiety and depression, borderline intellectual functioning, and learning deficits. According to the polysomnographic record, she had an apnea-hypopnea index (AHI) score of 8.2, a respiratory disturbance index (RDI) score of 11.6, and a mean oxygen saturation (SaO2) of 88%. Her Epworth sleepiness scale (ESS) score was 19, with a body mass index (BMI) of 21.7 kg/m2 (the 50th
FIGURE 1. A flowchart of the clinical pathway for orthodontic approaches in treating children with obstructive sleep apnea (OSA). First, the enlarged adenoid or tonsils are surgically removed. If residual symptoms of OSA exist, the origin should be evaluated further as either skeletal or soft tissue. When the degree of skeletal deformity is severe or residual growth will be negligible, orthognathic surgery can be performed. If the skeletal discrepancy is moderate and the growth potential is sufficient, growth modification can be performed, depending on the target area using orthopedic or functional appliances. Soft tissue problems underlying functional habits can be controlled by myofunctional therapy. It will reinforce the perioral and masticatory musculature and improve the tongue posture. If the patient is obese, weight loss should be encouraged. Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
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FIGURE 2. A-D, Initial photographs of the face and E-J, occlusion. The patient had a convex profile with a retruded chin, an open mouth, and constricted upper and lower dental arches, with moderate crowding, and a large overjet. (Fig 2 continued on next page.) Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
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FIGURE 2 (cont’d). Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
percentile BMI for an 11-year-old girl is 17.5 kg/m2), and she had a normal neck circumference. She was breathing hard through her mouth with her head tilted back at all times. On the facial and intraoral
examinations (Fig 2), the patient exhibited a convex profile with a retruded chin and protruded incompetent lips. Class I molar and Class II canine relationships were observed, with proclined upper
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incisors and a large overjet of 8 mm. Severely constricted upper and lower dental arches with a high palatal vault were found, with moderate crowding. Lateral cephalometric analysis (Fig 3, Table 1) was performed to evaluate the presence of craniofacial morphologic anomalies and parapharyngeal soft
tissue abnormalities, which are considered risk factors for OSA. She was diagnosed with a skeletal Class II hyperdivergent pattern with a retrognathic mandible and dental Class II, division 1. She was in cervical vertebral maturation stage 4, which meant that pubertal growth peak was impending. The retroglossal airway was severely constricted and
FIGURE 3. Initial lateral cephalogram. Skeletal Class II, with a retrognathic mandible and a hyperdivergent pattern, was seen in relation to the backward and downward position of the tongue and hyoid and a constricted oropharyngeal and hypopharyngeal airway width. Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
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Table 1. INITIAL CEPHALOMETRIC ANALYSIS OF CRANIOFACIAL PATTERN AND PARAPHARYNGEAL SOFT TISSUES, INCLUDING SOFT PALATE, AIRWAY, AND HYOID BONE
Measurement Compartment Craniofacial Saddle A ( ) SNA ( ) SNB ( ) ANB ( ) MPA ( ) LFH/TFH PFH/AFH Soft palate SPL (mm) SPT (mm) SPI ( ) Airway PNS-ad1 (mm) PNS-ad2 (mm) SPAS (mm) MAS (mm) IAS (mm) VAL (mm) Hyoid MPH (mm) H-C3RGN (mm) H-C3Me (mm) H-PTV (mm)
124 82 80 2 26 48 65
128 81.5 77 4.5 35 53.5 57.5
36 10 118
46.5 10 130
23 21 14 12 13 72
24 19.5 12 9 8 78.5
20.1 3.4 2.4 1
30.5 6.5 2 6.5
Abbreviations: ad1, the point where PNS-basion line intersects with the posterior pharyngeal wall; ad2, the point where a line perpendicular to sella-basion plane passing through PNS intersects with the posterior pharyngeal wall; AFH, anterior facial height; ANB, A point-nasion-B point angle; H-C3Me, perpendicular distance between hyoid bone (H) and the 3rd cervical vertebra (C3)-menton line; H-PTV, perpendicular distance between H and pterygoid vertical plane; IAS, inferior airway space; LFH, lower facial height; MAS, middle airway space; MPA, mandibular plane angle; MPH, perpendicular distance between H and mandibular plane; PFH, posterior facial height; PNS-ad1, distance between posterior nasal spine (PNS) and the point ad1; PNS-ad2, distance between PNS and the point ad2; SNA, sella-nasion-A point angle; SNB, sella-nasion-B point angle; SPAS, superior posterior airway space; SPI, soft palate inclination; SPL, soft palate length; SPT, soft palate thickness; TFH, total facial height; VAL, vertical airway length. Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
associated with a backward and downward tongue posture and hyoid bone position, which was confirmed by CBCT volumetric analysis. The treatment objective for alleviating her serious symptoms and complications caused by OSA was to advance the mandible, allowing forward and upward repositioning of the tongue base and hyoid bone and, ultimately, to enlarge the posterior airway space. Modified MMA surgery, accompanied by upper and lower anterior segmental osteotomies (ASOs), was planned. Although MMA protracts the posterior maxilla and chin, producing enlargement of the posterior upper airway, ASOs will aid in the improvement of the protruded facial profile. We planned the surgery to maintain the inclination of the occlusal plane, with the maxillary incisor retracted and keeping the baseline incisor exposure. The parents were informed of the possibility of a modified advancing genioplasty to stretch the suprahyoid and genioglossus musculature to be performed as a second intervention, if needed. After preoperative orthodontic treatment with rapid palatal expansion and teeth alignment for 7 months, the modified MMA surgery was performed simultaneously with 4 premolar extractions. The maxilla was advanced by 5 mm at the posterior nasal spine (PNS), but only 1.5 mm at the A-point level using segmental osteotomies. The upper first molars were protracted by 7 mm and the upper incisor tips were retracted by 4 mm along the initial occlusal plane, closing the extraction spaces surgically. The soft palate attached to the PNS showed a change in position and inclination, opening the retropalatal airway space by 8 mm (160% PNS change). In the mandible, the B-point was advanced by 2 mm, with an advancement of 7 mm at the chin point. Subsequently, the tongue base moved upward and forward, increasing the retroglossal airway space by 5 mm (71% chin point change). The volumetric analysis using the CBCT scans showed a pharyngeal airway volume increase of 177% and enlargement of the minimum cross-sectional area by 274%. The patient was excited by the improvement of her facial esthetics and respiratory function. Functional occlusion was obtained with a pleasing facial profile after 6 months of postoperative orthodontic treatment (Fig 4). The total treatment duration was 14 months.
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FIGURE 4. A-D, Final photographs of the face and E-J, occlusion. Functional occlusion was obtained with a pleasing facial profile. The patient’s lips were closed, with enhanced breathing. (Fig 4 continued on next page.) Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
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FIGURE 4 (cont’d). Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
The functional improvement was evaluated by a questionnaire and polysomnographic recording taken at 6 months after surgery. Considerable resolution of the OSA was found, with an AHI of 1.3, which consisted of hypopneas with no apnea, and an SaO2 of 94% (Table 2). She could sleep undisturbed, and most of her general symptoms had disappeared. She
no longer lost her breath after walking or lowering her head. The excessive daytime sleepiness had resolved enough for her to resume her studies and perform light exercise in school. The patient was longitudinally followed up every 6 months. The 4-year postretention photographic records showed a stable occlusion and facial
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Table 2. SUMMARY OF POLYSOMNOGRAPHIC RECORDS AND 3-DIMENSIONAL VOLUMETRIC AND CROSS-SECTIONAL MEASUREMENTS FROM CBCT IMAGES
Polysomnography BMI (kg/m2) 21.7 Sleep efficiency (%) 91.3 AHI 8.2 RERA 11.6 RDI 19.8 Supine AHI 9.4 SaO2 (%) 88.0 CBCT evaluation 3D airway volume 15,566.7 (mm3) Cross-sectional area (mm2) Minimum axial area 81.5 Retropalatal level 480.7 Retroglossal level 84.9
21.7 93.9 1.3 6.1 7.4 1.3 94.0
25.4 95.3 2.6 1.9 4.5 4.6 93.0
405.9 757.6 476.3
376.0 723.6 385.7
Abbreviations: 3D, 3-dimensional; AHI, apnea-hypopnea index; BMI, body mass index; CBCT, cone-beam computed tomography; RDI, respiratory disturbance index; RERA, respiratory event-related arousal; SaO2, oxygen saturation. Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
proportion (Fig 5). Her mouth breathing habit had disappeared. Superimposition of the lateral cephalometric films showed that the postoperative facial growth in this patient with OSA was negligible. One millimeter of additional mandibular forward growth without any remarkable maxillary changes since the MMA surgery was favorable for maintaining airway patency (Fig 6A). However, a slight rebound of an increased airway width was observed in the retroglossal area, with backward relapse of the hyoid position (Fig 6B). The CBCT measurements showed the dimensional relapse rates of the treatment effects to be 12.3% at the retropalatal level and 23.1% at the retroglossal level (Fig 7, Table 2). Although the supine AHI had increased by 3.3, supposedly in relation to the increased BMI (25.4 kg/m2), the AHI in the lateral sleep position was 0, and the reduction rate of the AHI was
68.3% (Table 2). Despite the small proportion of airway rebound, the improved breathing function and subjective symptoms and increased life and sleep quality accomplished with MMA remained intact. The ESS score was 3, and the patient no longer complained of daytime sleepiness.
Discussion Many of the clinical characteristics of pediatric OSA and the determinants of its epidemiology differ from those of adult OSA. The diagnostic criteria for OSA in adults have been determined by expert consensus and often include an AHI of 5 or greater on the nocturnal polysomnogram and evidence of disturbed or unrefreshing sleep, daytime sleepiness, or other daytime symptoms. AHI cutpoints of 5, 15, and 30 events per hour have been suggested to indicate mild, moderate, and severe levels of OSA.13 However, the rationale for specific AHI diagnostic criteria for children suffers from less available data and more heterogeneity across the studies. As yet, no international consensus has been reached regarding the AHI cutoff values for therapy initiation. At present, an AHI or RDI of 1 to 5 events per hour has been most often used in research to identify children with OSA.14,15 In the present case, the patient had an AHI of 8.2, which can result in significant morbidity. The present report provides the following clinical recommendations from an orthodontic viewpoint to be applied when considering skeletal surgery to treat OSA in children. First, we discuss the decision criteria for MMA surgery as definitive treatment. Historically, MMA surgery was performed only as a final option when conservative treatments or parapharyngeal soft tissue surgeries had failed.16 A recent protocol, however, aims for a selective one-step approach, because of the patients’ lack of motivation in undergoing multistep procedures.17 The determining factor should be the severity of the OSA symptoms and the skeletal discrepancy. In a patient with simple snoring or mild OSA and mild-to-moderate skeletal discrepancy, orthopedic or functional appliances to stimulate facial growth can be applied, along with myofunctional therapy, to control the abnormal habits, if TA surgery was
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FIGURE 5. A-D, Postretention photographs of the face and E-J, occlusion at 4 years postoperatively. Improved occlusion, facial proportion, and breathing function were stably maintained. (Fig 5 continued on next page.) Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
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FIGURE 5 (cont’d). Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
unnecessary or unsuccessful (Fig 1). However, in a patient with severe OSA and severe mandibular deficiency with a hyperdivergent pattern causing a severely constricted airway, MMA surgery is required, not only for early improvement of breathing function, but also because of the chance to change the growth direction to a more favorable one.
Children with skeletal Class II are classified as either poor responders or good responders according to their response to Class II treatment. Poor responders, with a hyperdivergent vertical pattern, posterior ramal inclination, large gonial angle, and weak musculature, are unlikely to undergo the anterior component of mandibular growth. This will aggravate the discrepancy between the maxilla and mandible and cause a
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FIGURE 6. Superimposition was performed to identify the A, postoperative changes and B, postretention changes, including residual facial growth. Although 1 mm of additional mandibular forward growth occurred without any remarkable maxillary changes after maxillomandibular advancement surgery, a slight rebound of an increased airway width was observed in the retroglossal area with backward relapse of the hyoid position, supposedly resulting from the increased body mass index. Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
lower tongue posture and a narrow retroglossal airway during growth. In such cases, MMA is the only option for changing the skeletal pattern by interrupting the vicious cycle of growth. Second, a proper surgical design is crucial for obtaining esthetic improvement and maximal enlargement of the airway. Modified MMA has been preferred, especially for Asian patients with protrusion because reshaping of the entire airway can be maximized without aggravating the facial profile.18 Moreover, early surgical intervention is possible by treating preoperative orthodontic tooth movement with segmental osteotomies. Also, a surgery-first approach can be tried initially to enhance sleep quality. Preoperative orthodontic retraction of the anterior teeth might deteriorate the respiratory problem by reducing the oral volume and moving the tongue
backward. In some patients with OSA and a steep occlusal plane, counterclockwise rotational MMA should be performed to advance the chin and hyoid.19 In the case of a flat occlusal plane or anterior protrusion, the surgical design can be effectively modified using segmental osteotomy or additional genioplasty.20 With regard to the stability after orthognathic surgery in growing patients, it has been controversial whether the surgical procedures can unexpectedly affect the postoperative facial growth21 or whether the facial growth will continue in its original pattern, negating the benefits of the surgery performed.22 Particularly in patients with skeletal Class II and a deficient mandible, the skeletal discrepancy can recur postoperatively because the maxilla will continue to grow and the mandible will maintain its deficient
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FIGURE 7. Cone-beam computed tomography images showing volumetric changes in the airway A-C, initially, D-F, 6 months after surgery, and G-I, 4 years after retention, in which the cross-sectional areas were measured at the retropalatal (Rp) and retroglossal (Rg) level. Even with a relapse rate of 12.3% at the retropalatal level and 23.1% at the retroglossal level, an overall 2.54-fold (postoperative) and 2.23-fold (postretentive) volumetric enlargement of the oropharyngeal airway was achieved. (Fig 7 continued on next page.) Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
growth rate,23 which would be in contrast to our results. Normal facial growth demonstrates completion of the maxillary growth earlier than that of the mandible. Therefore, after peak height velocity, the growth potential on the maxilla is rare, such as was shown in our case. Few studies have focused on the long-term efficacy of MMA in children. Bell and Turvey24 reported no more than a 50% success rate after MMA in children with OSA because of poor functional stability at 6 months postoperatively. However, their
study included only 8 children, most of whom had extreme skeletal deformities such as syndromic micrognathia or mandibular ankylosis, with a mean age of just 8.6 years. In conclusion, modified MMA surgery, combined with ASOs, was successful in our preadolescent patient with refractory OSA. Postoperative improvement occurred in the affected functions and esthetics, and the improvements were stable throughout the growth period.
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FIGURE 7 (cont’d). Ahn et al. Modified MMA for Refractory OSA. J Oral Maxillofac Surg 2015.
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