Available online at www.sciencedirect.com
British Journal of Oral and Maxillofacial Surgery 52 (2014) 445–451
Changes in the calibre of the upper airway and the surrounding structures after maxillomandibular advancement for obstructive sleep apnoea Yuh-Jia Hsieh a,b,c , Yu-Fang Liao a,b,c,d,e,∗ , Ning-Hung Chen d,e,f , Yu-Ray Chen a,b,d,e,g a
Craniofacial Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan Craniofacial Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan c Department of Craniofacial Orthodontics, Chang Gung Memorial Hospital, Taoyuan, Taiwan d Sleep Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan e College of Medicine, Chang Gung University, Taoyuan, Taiwan f Department of Pulmonary and Critical Care Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan g Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Linkou, Taiwan b
Accepted 7 February 2014 Available online 12 March 2014
Abstract Maxillomandibular advancement (MMA) is effective in the treatment of obstructive sleep apnoea. We aimed to assess changes in the calibre of the upper airway, facial skeleton, and surrounding structural position after MMA and their association with improvement in symptoms. Sixteen consecutive adults with moderate-to-severe apnoea were treated by primary MMA. Polysomnography and computed tomography (CT) of the head and neck were done before and at least 6 months after MMA. The calibre of the upper airway, the facial skeleton, and the surrounding structures were measured with image analysis software. After MMA, patients had a significant reduction in their apnoea-hypopnoea index (31.2 (18.8) number of events (n)/hour (h)). The mean (SD) volume of the airway increased significantly in the velopharynx (p < 0.01), oropharynx (p = 0.001), and hypopharynx (p < 0.001) (by 2.3 (2.4), 2.1 (2.6), and 1.7 (1.1) cm3 , respectively) and the length of the airway was significantly decreased (by 3.1 (3.5) mm p < 0.01). The soft palate (p < 0.001), tongue (p < 0.001), and hyoid (p = 0.001) moved significantly anteriorly (by 4.4 (2.0), 7.5 (2.8), and 5.7 (5.0) mm, respectively), and these movements were related to the MMA (r = 0.6–0.8). The improvement in the apnoea-hypopnoea index was associated with both maxillary advancement and anterior movements of the soft palate and hyoid (r = 0.6–0.7). The results of this study suggest that MMA increases the volume in the upper airway and reduces its length. Improvement in obstructive sleep apnoea is associated with the extent of the anterior movements of the maxilla, soft palate, and hyoid. © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Maxillomandibular advancement; Sleep apnoea; Segmental osteotomy
Introduction Maxillomandibular advancement (MMA) is used in the treatment of obstructive sleep apnoea as an effective alternative to
∗ Corresponding author at: Department of Craniofacial Orthodontics, Chang Gung Memorial Hospital, No. 123, Dinghu Road, Gueishan Township, Taoyuan 333, Taiwan. Tel.: +886 33196200x3500; fax: +886 33501997. E-mail addresses: [email protected], [email protected] (Y.-F. Liao).
continuous positive airway pressure (CPAP).1 While CPAP remains the gold standard because it is highly efficacious, other options are needed because the clinical effectiveness of CPAP is often limited because patients find it difficult to tolerate.2 MMA advances the maxilla and mandible to increase the calibre of the upper airway, thereby preventing its collapse during sleep. However, the mechanisms by which MMA improves sleep apnoea are not well understood. Although MMA has been shown to improve the calibre of the upper airway,3–14 these studies predominantly used
0266-4356/$ – see front matter © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bjoms.2014.02.006
446
Y.-J. Hsieh et al. / British Journal of Oral and Maxillofacial Surgery 52 (2014) 445–451
cephalometric radiographs for assessment. Such measurements have the disadvantage that the images are usually taken with the patient upright (not a natural sleeping position), and a lateral cephalometric view of the airway limits its 3dimensional form by not capturing the width of the airway. The surrounding structures (soft palate, tongue, and hyoid), the interaction between the upper airway and the surrounding structures, and the response to treatment, have never been systematically studied to our knowledge in patients treated by MMA. Computed tomography (CT) is probably one of the best methods for assessment of the 3-dimensional structures of the upper airway, facial skeleton, and surroundings. In this study we aimed to evaluate the mechanism that underlies MMA in patients with obstructive sleep apnoea, and we used CT to assess the effects on the calibre of the upper airway and on the surrounding structures when the patient was awake.
Patients and methods Patients We prospectively recruited adult patients with obstructive sleep apnoea from the Sleep Centre for primary treatment with MMA. Patients were included if they had at least 2 symptoms of sleep apnoea (snoring, witnessed apnoeas, fragmented sleep, or daytime sleepiness) and they had moderate-to-severe obstructive sleep apnoea on nocturnal polysomnography (apnoea-hypopnoea index (AHI) ≥ 15 n/h).15,16 Patients were excluded if they had cleft palate, genetic syndromes, or were unable to comply with the follow-up evaluations required. The study was approved by the hospital’s Institutional Review Board. Treatment with MMA MMA was modified. Briefly, the modified technique consisted of anterior segmental osteotomies with the standard Le Fort I and bilateral sagittal split osteotomies. The anterior segmental osteotomies typically involved an anterior maxillary osteotomy or a reverse-T mandibular osteotomy. The intention was to achieve maximal advancement while maintaining a balanced facial appearance because most of our patients had bimaxillary protrusion preoperatively. Polysomnography We used polysomnography to assess outcomes of treatment at least 6 months after MMA, with scoring according to standard criteria.15,16 Apnoeas were defined by cessation of airflow for at least 10 s in association with at least 3% oxygen desaturation or arousal. Hypopnoeas were defined as a reduced amplitude of airflow, measured using nasal pressure or movement of the thoracoabdominal wall, of >50% of the baseline measurement for >10 s in association with at least
3% oxygen desaturation or arousal. The AHI was defined as the combined number of apnoeic and hypopnoeic events/h of total sleep. Each patient’s age, sex, height, and weight were also recorded. Computed tomography Spiral CT of the head and neck was done with the patient awake, before and at least 6 months after MMA, using a SOMATOM Sensation 64 CT scanner (Siemens, Germany). The patient’s head was positioned with the Frankfort horizontal (FH) plane perpendicular to the ground. Throughout the scan, patients were asked not to swallow, and were also instructed to keep the mouth closed and to maintain a centric occlusion bite. Scanning of the head and neck was acquired during endexpiration in 50% improvement in AHI and postoperative AHI < 20 n/h. Calibre of the upper airway before and after MMA
Fig. 2. Facial skeletal and surrounding structural landmarks on mid-sagittal computed tomographic scan: ANS, anterior nasal spine; PNS, posterior nasal spine; Pog, pogonion; SP, soft palate; T, tongue, and H, hyoid.
The AP and CSA increased significantly at all levels (all p < 0.01) except the 10th, but the LAT increased significantly only from the 3rd to the 7th level (all p < 0.01). Velopharyngeal, oropharyngeal, and hypopharyngeal volumes increased significantly together with minimum CSA (all p < 0.01) (Table 1).
448
Y.-J. Hsieh et al. / British Journal of Oral and Maxillofacial Surgery 52 (2014) 445–451
Table 1 Mean (SD) – calibre of the airway, and positions of the facial skeleton and surrounding structures before and after maxillomandibular advancement. Variable
P value
Before MMA
After MMA
Length of airway (mm)
72.8 (7.6)
69.7 (7.4)
British Journal of Oral and Maxillofacial Surgery 52 (2014) 445–451
Changes in the calibre of the upper airway and the surrounding structures after maxillomandibular advancement for obstructive sleep apnoea Yuh-Jia Hsieh a,b,c , Yu-Fang Liao a,b,c,d,e,∗ , Ning-Hung Chen d,e,f , Yu-Ray Chen a,b,d,e,g a
Craniofacial Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan Craniofacial Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan c Department of Craniofacial Orthodontics, Chang Gung Memorial Hospital, Taoyuan, Taiwan d Sleep Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan e College of Medicine, Chang Gung University, Taoyuan, Taiwan f Department of Pulmonary and Critical Care Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan g Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Linkou, Taiwan b
Accepted 7 February 2014 Available online 12 March 2014
Abstract Maxillomandibular advancement (MMA) is effective in the treatment of obstructive sleep apnoea. We aimed to assess changes in the calibre of the upper airway, facial skeleton, and surrounding structural position after MMA and their association with improvement in symptoms. Sixteen consecutive adults with moderate-to-severe apnoea were treated by primary MMA. Polysomnography and computed tomography (CT) of the head and neck were done before and at least 6 months after MMA. The calibre of the upper airway, the facial skeleton, and the surrounding structures were measured with image analysis software. After MMA, patients had a significant reduction in their apnoea-hypopnoea index (31.2 (18.8) number of events (n)/hour (h)). The mean (SD) volume of the airway increased significantly in the velopharynx (p < 0.01), oropharynx (p = 0.001), and hypopharynx (p < 0.001) (by 2.3 (2.4), 2.1 (2.6), and 1.7 (1.1) cm3 , respectively) and the length of the airway was significantly decreased (by 3.1 (3.5) mm p < 0.01). The soft palate (p < 0.001), tongue (p < 0.001), and hyoid (p = 0.001) moved significantly anteriorly (by 4.4 (2.0), 7.5 (2.8), and 5.7 (5.0) mm, respectively), and these movements were related to the MMA (r = 0.6–0.8). The improvement in the apnoea-hypopnoea index was associated with both maxillary advancement and anterior movements of the soft palate and hyoid (r = 0.6–0.7). The results of this study suggest that MMA increases the volume in the upper airway and reduces its length. Improvement in obstructive sleep apnoea is associated with the extent of the anterior movements of the maxilla, soft palate, and hyoid. © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Maxillomandibular advancement; Sleep apnoea; Segmental osteotomy
Introduction Maxillomandibular advancement (MMA) is used in the treatment of obstructive sleep apnoea as an effective alternative to
∗ Corresponding author at: Department of Craniofacial Orthodontics, Chang Gung Memorial Hospital, No. 123, Dinghu Road, Gueishan Township, Taoyuan 333, Taiwan. Tel.: +886 33196200x3500; fax: +886 33501997. E-mail addresses: [email protected], [email protected] (Y.-F. Liao).
continuous positive airway pressure (CPAP).1 While CPAP remains the gold standard because it is highly efficacious, other options are needed because the clinical effectiveness of CPAP is often limited because patients find it difficult to tolerate.2 MMA advances the maxilla and mandible to increase the calibre of the upper airway, thereby preventing its collapse during sleep. However, the mechanisms by which MMA improves sleep apnoea are not well understood. Although MMA has been shown to improve the calibre of the upper airway,3–14 these studies predominantly used
0266-4356/$ – see front matter © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bjoms.2014.02.006
446
Y.-J. Hsieh et al. / British Journal of Oral and Maxillofacial Surgery 52 (2014) 445–451
cephalometric radiographs for assessment. Such measurements have the disadvantage that the images are usually taken with the patient upright (not a natural sleeping position), and a lateral cephalometric view of the airway limits its 3dimensional form by not capturing the width of the airway. The surrounding structures (soft palate, tongue, and hyoid), the interaction between the upper airway and the surrounding structures, and the response to treatment, have never been systematically studied to our knowledge in patients treated by MMA. Computed tomography (CT) is probably one of the best methods for assessment of the 3-dimensional structures of the upper airway, facial skeleton, and surroundings. In this study we aimed to evaluate the mechanism that underlies MMA in patients with obstructive sleep apnoea, and we used CT to assess the effects on the calibre of the upper airway and on the surrounding structures when the patient was awake.
Patients and methods Patients We prospectively recruited adult patients with obstructive sleep apnoea from the Sleep Centre for primary treatment with MMA. Patients were included if they had at least 2 symptoms of sleep apnoea (snoring, witnessed apnoeas, fragmented sleep, or daytime sleepiness) and they had moderate-to-severe obstructive sleep apnoea on nocturnal polysomnography (apnoea-hypopnoea index (AHI) ≥ 15 n/h).15,16 Patients were excluded if they had cleft palate, genetic syndromes, or were unable to comply with the follow-up evaluations required. The study was approved by the hospital’s Institutional Review Board. Treatment with MMA MMA was modified. Briefly, the modified technique consisted of anterior segmental osteotomies with the standard Le Fort I and bilateral sagittal split osteotomies. The anterior segmental osteotomies typically involved an anterior maxillary osteotomy or a reverse-T mandibular osteotomy. The intention was to achieve maximal advancement while maintaining a balanced facial appearance because most of our patients had bimaxillary protrusion preoperatively. Polysomnography We used polysomnography to assess outcomes of treatment at least 6 months after MMA, with scoring according to standard criteria.15,16 Apnoeas were defined by cessation of airflow for at least 10 s in association with at least 3% oxygen desaturation or arousal. Hypopnoeas were defined as a reduced amplitude of airflow, measured using nasal pressure or movement of the thoracoabdominal wall, of >50% of the baseline measurement for >10 s in association with at least
3% oxygen desaturation or arousal. The AHI was defined as the combined number of apnoeic and hypopnoeic events/h of total sleep. Each patient’s age, sex, height, and weight were also recorded. Computed tomography Spiral CT of the head and neck was done with the patient awake, before and at least 6 months after MMA, using a SOMATOM Sensation 64 CT scanner (Siemens, Germany). The patient’s head was positioned with the Frankfort horizontal (FH) plane perpendicular to the ground. Throughout the scan, patients were asked not to swallow, and were also instructed to keep the mouth closed and to maintain a centric occlusion bite. Scanning of the head and neck was acquired during endexpiration in 50% improvement in AHI and postoperative AHI < 20 n/h. Calibre of the upper airway before and after MMA
Fig. 2. Facial skeletal and surrounding structural landmarks on mid-sagittal computed tomographic scan: ANS, anterior nasal spine; PNS, posterior nasal spine; Pog, pogonion; SP, soft palate; T, tongue, and H, hyoid.
The AP and CSA increased significantly at all levels (all p < 0.01) except the 10th, but the LAT increased significantly only from the 3rd to the 7th level (all p < 0.01). Velopharyngeal, oropharyngeal, and hypopharyngeal volumes increased significantly together with minimum CSA (all p < 0.01) (Table 1).
448
Y.-J. Hsieh et al. / British Journal of Oral and Maxillofacial Surgery 52 (2014) 445–451
Table 1 Mean (SD) – calibre of the airway, and positions of the facial skeleton and surrounding structures before and after maxillomandibular advancement. Variable
P value
Before MMA
After MMA
Length of airway (mm)
72.8 (7.6)
69.7 (7.4)
