- Email: [email protected]
Cephalometric Measurement of Upper Airway Length Correlates With the Presence and Severity of Obstructive Sleep Apnea
Oral Abstract Session 1 ORTHOGNATHIC Thursday, September 30, 2010, 8:00 am - 11:00 am
Cone-Beam Computed Tomography Airway Evaluation Due to MaxilloMandibular Counterclockwise Rotation and Mandibular Advancement With TMJ Concepts Total Joint Prostheses D. Rodrigues, A. Vianna, L. Wolford: Texas A&M University Health Science Center, Baylor College of Dentistry, J. Goncalves, D. Goncalves Statement of the Problem: 3-dimensional (3D) analysis of the airway has become more commom with the technological advance of both imaging and computer analysis. The purpose of this study was to evaluate, three-dimensionally, the anatomical changes of the oropharyngeal airway following temporomandibular (TMJ) reconstruction and mandibular advancement with TMJ Concepts custom fitted total joint prosthesis, maxillary osteotomies, and counter-clockwise rotation of the maxillo-mandibular complex. Materials and Methods: This is a retrospective study evaluating cone beam computed tomography (CB/CT) scan of patients that underwent TMJ reconstruction and counter-clockwise rotation of the maxillo-mandibular complex. All patients were operated by one surgeon between December 2008 and October 2009. CB/CT scans were performed with the iCATTM Cone Beam 3-D Imaging System (Imaging Science International, Hatfield, PA). Pre-surgical (T1) records were taken 1 day (range 1-2) before the surgery, immediate post-surgical (T2) records were taken 5 days (range 3-9) after surgery and long-term follow-up (T3) records taken 6-12 months after surgery. After the 3D volume was imported and properly oriented, the airway analysis tool was used to define the portion of the airway of interest. This portion comprised the velopharynx (retropalatal region) and the oropharynx (retroglossal region). The superior border was defined as the posterior nasal spine of the hard palate to the posterior wall of the pharynx [parallel to Frankfort Horizontal (FH)]; the inferior border was the tip of the epiglottis on a plane parallel to FH. The border between the velopharynx and the oropharynx was the tip of the soft palate. The Dolphin software (Dolphin Imaging Sciences, Chatsworth, CA) airway analysis tool calculated the airway volume area, airway area, and minimal axial area of retropalatal and retroglossal regions. On the 2 dimensional (2D) protocol the cephalograms were obtained through the Dolphin volume and the 2D measurements were created to evaluate surgical movement. TraAAOMS • 2010
ditional vertical and AP measurements were performed. The method reproducibility was verified by Dalberg’s analysis. Multiple regression statistical analysis was used to verify the role of several anatomical structures’ changes in airway dimensional changes. Results of Investigation: There were 27 female patients treated during this period. Mean patient age at the time of surgery was 44 years (range, 13 years to 62 years). The average change in airway area, volume, and minimal axial area increased, respectively, 90 mm2, 3500 mm3, and 100 mm2 at the longest term follow up. Pearson correlation showed a significant correlation between the amount of maxillo-mandibular advancement and the 3D airway changes. Conclusion: The results of this study showed an increase in all variables analyzed and a significant correlation between the amount of maxillo-mandibular advancement and the 3D airway changes. References: Goncalves J et al: Postsurgical Stability of Oropharyngeal Airway Changes Following Counter-Clockwise Maxillo-Mandibular Advancement Surgery. J Oral Maxillofac Surg 64:755-762, 2006 Haskell, J et al: Effects of Mandibular Advancement Device (MAD) on Airway Dimensions Assessed with Cone-Bean Computed Tomography. Semin Orthod 2009; 15: 132 - 158
Cephalometric Measurement of Upper Airway Length Correlates With the Presence and Severity of Obstructive Sleep Apnea S. Susarla: Massachusetts General Hospital, Z. Abramson, T. Dodson, L. Kaban Statement of the Problem: Obstructive sleep apnea (OSA), a breathing disorder characterized by intermittent collapse of the pharyngeal airway, is a disease of increasing relevance to oral and maxillofacial surgeons. Previous studies have reported that patients with OSA, when compared to non-OSA patients, have longer upper airways on maxillofacial computed tomograms (CT) and magnetic resonance imaging studies. In addition, it has been demonstrated that the upper airway is longer in males versus females. Since the lateral cephalogram is an inexpensive study with minimal radiation exposure, it would be a desirable substitute for the CT scan to measure airway length. The purpose of this study was to measure upper airway length (UAL) on lateral cephalograms and to assess its relationship to the presence and severity of obstructive sleep apnea (OSA). We hypothee-1
Oral Abstract Session 1 sized that upper airway length would be longer in patients with OSA and strongly correlated with disease severity. Methods of Investigation: This was a case-control study utilizing a sample of cases defined as adult subjects with OSA, confirmed by polysomnography, and controls who were adult patients with skeletal Class II malocclusions (non-syndromic mandibular or bimaxillary retrognathia) without history or symptoms of OSA. The primary predictor variable was UAL, which was measured as the distance along the long axis of the airway from the hyoid bone to the palatal plane. Two observers, blinded to the disease status of the subjects, independently evaluated airway length to assess the reliability of the measurement method. The technique had a high degree of inter-examiner correlation (intra-class correlation coefficient ⫽ 0.96, p ⬍ 0.001). Other variables were demographic (age, sex and body mass index, BMI) and cephalometric (maxillary sagittal position, SNA; mandibular sagittal position, SNB; maxillomandibular relationship, ANB; maxillary length, Co-ANS; mandibular length, CoGn; posterior airway space, PAS; hyoid-mandibular perpendicular distance, HMP; soft-palate length, PNS-SP; maxillary vertical length, S-PNS) parameters. The respiratory disturbance index (RDI) was used to measure disease severity in cases. Methods of Analysis: Bivariate and multiple regression analyses were computed to evaluate the association between predictor and outcome variables adjusted as indicated for confounders or effect modifiers. Diagnostic test characteristics were computed for threshold airway lengths. A p-value ⬍ 0.05 was statistically significant. Results: Over a five-year period, we identified 96 cases with OSA (76 males) and 56 controls (36 males). OSA subjects were older, predominately male, had higher BMIs, and longer and narrower airways (P ⬍ 0.05). The OSA group had a mean RDI of 51.3 ⫾ 31.4 events/hr. After controlling for confounding variables, UALs ⬎72 mm for males and ⬎62 mm for females were significantly associated with presence of OSA. Using these thresholds as a diagnostic test for the presence of OSA, the sensitivity and specificity were ⬎ 0.8. UAL was strongly correlated with RDI in males (r ⫽ 0.72, p ⬍ 0.01) and moderately correlated with RDI in females (r ⫽ 0.52, p ⬍ 0.01). Conclusion: Upper airway length can be reliably measured on lateral cephalograms and is correlated with the presence and severity of OSA in adult patients. References: Abramson ZR, Susarla SM, Troulis MJ, Kaban LB. Three-Dimensional CT Analysis of Airway Anatomy in Patients With Obstructive Sleep Apnea. J Oral Maxillofac Surg 2008: 66(8-S), 60. Segal Y, Malhotra A, Pillar G. Upper airway length may be associated with the severity of obstructive sleep apnea syndrome. Sleep Breath. 2008 Nov;12(4):311-6. Malhotra A, Huang Y, Fogel RB, Pillar G, Edwards JK, Kikinis R, Loring SH, White DP. The male predisposition to pharyngeal collapse:
e-2
importance of airway length. Am J Respir Crit Care Med. 2002 Nov 15;166(10):1388-95.
Development of a Normative Data Set for the Normal Adult Airway Using 772 Cone Beam CT Scans J. Smith: University of Michigan, S. Edwards, R. Conley, M. Smith Statement of the Problem: There is an increasing interest with preoperatively evaluating patients undergoing surgical management for obstructive sleep apnea with cephalograms and volumetric cone beam computed tomography (CBCT). Normative means and correlative measures must therefore be established to define the adult airway in two-dimensions (2D) and three-dimensions (3D). Materials and Methods: 772 CBCT scans (539 females and 233 males) were collected from a private practice oral and maxillofacial radiology practice in Sacramento, CA. Any CBCTs acquired for sleep apnea or pathology were excluded. All CBCT scans were evaluated in Dolphin v.10.5 for 2D cephalometric analysis and 3dMD Vultus for 3D airway analysis. A custom cephalometric analysis, consisting of both skeletal and soft tissue measures, was completed on all scans. 3D analysis included linear airway dimensions, airway volume, airway length, minimum cross-sectional area of the airway and location of the minimum cross-sectional area in relation to the palatal plane. Methods of Data Analysis: Data were analyzed looking for association of airway measurements with gender, age, and a combination of the two. Means, standard deviations and differences between groups were calculated for all 2D and 3D measures. Results of Investigation: Measures of the airway in 2D were significantly different between males and females. Females had a narrowing of the airway with increasing age, and the narrowest measure of the airway in 2D was statistically smaller, located most commonly at the level of the occlusal plane. Males demonstrated a greater mean mandibular plane to hyoid distance. There were significant differences between males and females on most 3D measures. The minimum cross-sectional area moved superiorly with age in both genders and was significantly larger in males (172.14 mm2 versus 149.58 mm2 in females). Total airway volume in males is a mean of 16.4 cm3 and in females is a mean of 11.8 cm3. Airway volume tends to decrease with increasing age in females only. The mean length of the airway in males is 59.6 mm and in females is 46.9 mm. 2D and 3D measures of the airway have a moderate to high correlation at the level of the palatal plane, occlusal plane, superior of C3 and inferior of C3. Conclusion: Gender and age seem to play a role in airway dimensions and may reflect a pattern of change AAOMS • 2010
Cone-Beam Computed Tomography Airway Evaluation Due to MaxilloMandibular Counterclockwise Rotation and Mandibular Advancement With TMJ Concepts Total Joint Prostheses D. Rodrigues, A. Vianna, L. Wolford: Texas A&M University Health Science Center, Baylor College of Dentistry, J. Goncalves, D. Goncalves Statement of the Problem: 3-dimensional (3D) analysis of the airway has become more commom with the technological advance of both imaging and computer analysis. The purpose of this study was to evaluate, three-dimensionally, the anatomical changes of the oropharyngeal airway following temporomandibular (TMJ) reconstruction and mandibular advancement with TMJ Concepts custom fitted total joint prosthesis, maxillary osteotomies, and counter-clockwise rotation of the maxillo-mandibular complex. Materials and Methods: This is a retrospective study evaluating cone beam computed tomography (CB/CT) scan of patients that underwent TMJ reconstruction and counter-clockwise rotation of the maxillo-mandibular complex. All patients were operated by one surgeon between December 2008 and October 2009. CB/CT scans were performed with the iCATTM Cone Beam 3-D Imaging System (Imaging Science International, Hatfield, PA). Pre-surgical (T1) records were taken 1 day (range 1-2) before the surgery, immediate post-surgical (T2) records were taken 5 days (range 3-9) after surgery and long-term follow-up (T3) records taken 6-12 months after surgery. After the 3D volume was imported and properly oriented, the airway analysis tool was used to define the portion of the airway of interest. This portion comprised the velopharynx (retropalatal region) and the oropharynx (retroglossal region). The superior border was defined as the posterior nasal spine of the hard palate to the posterior wall of the pharynx [parallel to Frankfort Horizontal (FH)]; the inferior border was the tip of the epiglottis on a plane parallel to FH. The border between the velopharynx and the oropharynx was the tip of the soft palate. The Dolphin software (Dolphin Imaging Sciences, Chatsworth, CA) airway analysis tool calculated the airway volume area, airway area, and minimal axial area of retropalatal and retroglossal regions. On the 2 dimensional (2D) protocol the cephalograms were obtained through the Dolphin volume and the 2D measurements were created to evaluate surgical movement. TraAAOMS • 2010
ditional vertical and AP measurements were performed. The method reproducibility was verified by Dalberg’s analysis. Multiple regression statistical analysis was used to verify the role of several anatomical structures’ changes in airway dimensional changes. Results of Investigation: There were 27 female patients treated during this period. Mean patient age at the time of surgery was 44 years (range, 13 years to 62 years). The average change in airway area, volume, and minimal axial area increased, respectively, 90 mm2, 3500 mm3, and 100 mm2 at the longest term follow up. Pearson correlation showed a significant correlation between the amount of maxillo-mandibular advancement and the 3D airway changes. Conclusion: The results of this study showed an increase in all variables analyzed and a significant correlation between the amount of maxillo-mandibular advancement and the 3D airway changes. References: Goncalves J et al: Postsurgical Stability of Oropharyngeal Airway Changes Following Counter-Clockwise Maxillo-Mandibular Advancement Surgery. J Oral Maxillofac Surg 64:755-762, 2006 Haskell, J et al: Effects of Mandibular Advancement Device (MAD) on Airway Dimensions Assessed with Cone-Bean Computed Tomography. Semin Orthod 2009; 15: 132 - 158
Cephalometric Measurement of Upper Airway Length Correlates With the Presence and Severity of Obstructive Sleep Apnea S. Susarla: Massachusetts General Hospital, Z. Abramson, T. Dodson, L. Kaban Statement of the Problem: Obstructive sleep apnea (OSA), a breathing disorder characterized by intermittent collapse of the pharyngeal airway, is a disease of increasing relevance to oral and maxillofacial surgeons. Previous studies have reported that patients with OSA, when compared to non-OSA patients, have longer upper airways on maxillofacial computed tomograms (CT) and magnetic resonance imaging studies. In addition, it has been demonstrated that the upper airway is longer in males versus females. Since the lateral cephalogram is an inexpensive study with minimal radiation exposure, it would be a desirable substitute for the CT scan to measure airway length. The purpose of this study was to measure upper airway length (UAL) on lateral cephalograms and to assess its relationship to the presence and severity of obstructive sleep apnea (OSA). We hypothee-1
Oral Abstract Session 1 sized that upper airway length would be longer in patients with OSA and strongly correlated with disease severity. Methods of Investigation: This was a case-control study utilizing a sample of cases defined as adult subjects with OSA, confirmed by polysomnography, and controls who were adult patients with skeletal Class II malocclusions (non-syndromic mandibular or bimaxillary retrognathia) without history or symptoms of OSA. The primary predictor variable was UAL, which was measured as the distance along the long axis of the airway from the hyoid bone to the palatal plane. Two observers, blinded to the disease status of the subjects, independently evaluated airway length to assess the reliability of the measurement method. The technique had a high degree of inter-examiner correlation (intra-class correlation coefficient ⫽ 0.96, p ⬍ 0.001). Other variables were demographic (age, sex and body mass index, BMI) and cephalometric (maxillary sagittal position, SNA; mandibular sagittal position, SNB; maxillomandibular relationship, ANB; maxillary length, Co-ANS; mandibular length, CoGn; posterior airway space, PAS; hyoid-mandibular perpendicular distance, HMP; soft-palate length, PNS-SP; maxillary vertical length, S-PNS) parameters. The respiratory disturbance index (RDI) was used to measure disease severity in cases. Methods of Analysis: Bivariate and multiple regression analyses were computed to evaluate the association between predictor and outcome variables adjusted as indicated for confounders or effect modifiers. Diagnostic test characteristics were computed for threshold airway lengths. A p-value ⬍ 0.05 was statistically significant. Results: Over a five-year period, we identified 96 cases with OSA (76 males) and 56 controls (36 males). OSA subjects were older, predominately male, had higher BMIs, and longer and narrower airways (P ⬍ 0.05). The OSA group had a mean RDI of 51.3 ⫾ 31.4 events/hr. After controlling for confounding variables, UALs ⬎72 mm for males and ⬎62 mm for females were significantly associated with presence of OSA. Using these thresholds as a diagnostic test for the presence of OSA, the sensitivity and specificity were ⬎ 0.8. UAL was strongly correlated with RDI in males (r ⫽ 0.72, p ⬍ 0.01) and moderately correlated with RDI in females (r ⫽ 0.52, p ⬍ 0.01). Conclusion: Upper airway length can be reliably measured on lateral cephalograms and is correlated with the presence and severity of OSA in adult patients. References: Abramson ZR, Susarla SM, Troulis MJ, Kaban LB. Three-Dimensional CT Analysis of Airway Anatomy in Patients With Obstructive Sleep Apnea. J Oral Maxillofac Surg 2008: 66(8-S), 60. Segal Y, Malhotra A, Pillar G. Upper airway length may be associated with the severity of obstructive sleep apnea syndrome. Sleep Breath. 2008 Nov;12(4):311-6. Malhotra A, Huang Y, Fogel RB, Pillar G, Edwards JK, Kikinis R, Loring SH, White DP. The male predisposition to pharyngeal collapse:
e-2
importance of airway length. Am J Respir Crit Care Med. 2002 Nov 15;166(10):1388-95.
Development of a Normative Data Set for the Normal Adult Airway Using 772 Cone Beam CT Scans J. Smith: University of Michigan, S. Edwards, R. Conley, M. Smith Statement of the Problem: There is an increasing interest with preoperatively evaluating patients undergoing surgical management for obstructive sleep apnea with cephalograms and volumetric cone beam computed tomography (CBCT). Normative means and correlative measures must therefore be established to define the adult airway in two-dimensions (2D) and three-dimensions (3D). Materials and Methods: 772 CBCT scans (539 females and 233 males) were collected from a private practice oral and maxillofacial radiology practice in Sacramento, CA. Any CBCTs acquired for sleep apnea or pathology were excluded. All CBCT scans were evaluated in Dolphin v.10.5 for 2D cephalometric analysis and 3dMD Vultus for 3D airway analysis. A custom cephalometric analysis, consisting of both skeletal and soft tissue measures, was completed on all scans. 3D analysis included linear airway dimensions, airway volume, airway length, minimum cross-sectional area of the airway and location of the minimum cross-sectional area in relation to the palatal plane. Methods of Data Analysis: Data were analyzed looking for association of airway measurements with gender, age, and a combination of the two. Means, standard deviations and differences between groups were calculated for all 2D and 3D measures. Results of Investigation: Measures of the airway in 2D were significantly different between males and females. Females had a narrowing of the airway with increasing age, and the narrowest measure of the airway in 2D was statistically smaller, located most commonly at the level of the occlusal plane. Males demonstrated a greater mean mandibular plane to hyoid distance. There were significant differences between males and females on most 3D measures. The minimum cross-sectional area moved superiorly with age in both genders and was significantly larger in males (172.14 mm2 versus 149.58 mm2 in females). Total airway volume in males is a mean of 16.4 cm3 and in females is a mean of 11.8 cm3. Airway volume tends to decrease with increasing age in females only. The mean length of the airway in males is 59.6 mm and in females is 46.9 mm. 2D and 3D measures of the airway have a moderate to high correlation at the level of the palatal plane, occlusal plane, superior of C3 and inferior of C3. Conclusion: Gender and age seem to play a role in airway dimensions and may reflect a pattern of change AAOMS • 2010