Three-Dimensional Airway Changes in Children With Congenital Micrognathia and Obstructive Sleep Apnea Following Mandibular Distraction Osteogenesis

Oral Abstract Session 3 were included in this study. The same scanning protocol was applied to all patients and involved the intravenous injection of the bone targeting radiopharmaceutical 99mTc MDP (7.4 MBq/kg, maximum of 518 MBq). 3-D regions-of-interest (ROIs) were applied to the condyles and maximum counts of both condyles. Methods of Data Analysis: Data from each condyle was standardized to an external source and a ratio of R/L condylar uptake was calculated and compared to agematched normal values. The uptake ratio was determined to be high, normal, or low. Each patient was then categorized as normal or abnormal, symmetric or asymmetric based on blinded evaluation of the SPECT scan results. Patient records were then obtained and results of the SPECT scans were compared to the clinical assessment and follow up data. Results of Investigation: Eleven patients (n ⫽ 11, 0 male, 11 female, ages 12-44 years, mean ⫽ 19) were referred for a SPECT Tc99 scan of the condyles. Five of the scans showed normal and symmetric activity bilaterally. All of these patients had quiescent or end-stage growth abnormalities and the SPECT results correlated with their clinical diagnosis. Two of these scans exhibited abnormal R/L ratios and this correlated with the clinical diagnosis of condylar hyperplasia on the side with increased uptake. Four scans demonstrated bilateral symmetric uptake with higher-than-normal activity. Two of the 4 exhibited continued symmetric growth clinically and the other two had active bilateral idiopathic condylar resorption. Conclusion: The results of this preliminary study indicate that age-matched normative data is useful in evaluating asymmetric and symmetric abnormalities in mandibular growth. The application of established agematched normal ranges of condylar activity using SPECT Tc99 is useful in guiding the management of patients with suspected condylar hyperplasia, condylar hypoplasia, and idiopathic condylar resorption and may be useful in assessment of activity of inflammatory joint disease. References: Kaban LB, Cisneros GJ, Heyman S, Treves S. Assessment of mandibular growth by skeletal scintigraphy. J Oral Maxillofac Surg. 1982; 40:18-22. Fahey FH, Abramson ZR, Padwa BL, Zimmerman RE, Zurakowski D, Nissenbaum M, Kaban LB, Treves ST. Use of (99m)Tc-MDP SPECT for assessment of mandibular growth: development of normal values. Eur J Nucl Med Mol Imaging. 2010; 37: 1002-10.

Three-Dimensional Airway Changes in Children With Congenital Micrognathia and Obstructive Sleep Apnea Following Mandibular Distraction Osteogenesis Z. Abramson: Massachusetts General Hospital, M. Lawler, S. Susarla, M. Troulis, L. Kaban e-24

Statement of the Problem: Children with congenital micrognathia often suffer from significant morbidity from obstructive sleep apnea (OSA) and frequently require a tracheostomy. Mandibular lengthening by distraction osteogenesis (DO) has been shown to relieve OSA symptoms and to allow for decannulation in those infants and children with tracheostomies. Upper airway enlargement as a result of mandibular lengthening is presumed to be the source of this clinical improvement, however, the 3-dimensional airway changes in response to DO have not been well documented in the literature. Materials and Methods: Patients with micrognathia and OSA who underwent mandibular DO and had pre- and post-distraction CT scans were included in this retrospective case series. Pre and post-op digital 3-D CT reconstructions were created and measurements of airway size and shape were obtained. Pre and post-distraction respiratory disturbance index (RDI), oxygen saturation nadir (LSAT), nasopharyngoscopic exams, and presence of tracheostomy were recorded when available. Methods of Data Analysis: The methodology for image acquisition and analysis described in this paper has been previously published by the authors. Scans were imported into a CT analyzing computer software (3-D Slicer), developed at the Harvard Surgical Planning Laboratory (SPL; Brigham and Women’s Hospital, Boston, MA). Digital 3-dimensional (3-D) model reconstructions of the airways were made. Once 3-D digital models were constructed, measurements of airway size and shape were obtained. With use of a computer software package (SPSS Graduate Pack 11.0; SPSS Inc, Chicago, IL), descriptive statistics were computed for all airway data and for all patients pre and post distraction. Significant differences between pre- and post-distraction airway measures were computed using a Wilcoxon Signed-Rank test. For all analyses, P values ⬍ .05 were considered statistically significant. Results of Investigation: Eleven patients (M:F ⫽ 4:2, ages 1-19) with congenital micrognathia met the inclusion criteria. All patients demonstrated improvement in parameters of airway size including increased volume, as well as increased retropalatal, regtroglossal, and average cross-sectional area, and all airways were more uniform in shape. All patients demonstrated improvement in clinical symptoms, polysomnography, oxygen saturation, and/or had tracheostomy decannulation after DO. Conclusion: Increases in upper airway average crosssectional area (retropalatal, retroglossal, average), retroglossal lateral and anteroposterior distances, and airway uniformity after mandibular DO accompanied improvements in sleep and breathing in these patients with micrognathia and OSA. References: Steinbacher DM, Kaban LB, Troulis MJ. Mandibular Advancement by Distraction Osteogenesis for Tracheotomy-Dependent Children With Severe Micrognathia. J. Oral Maxillofac. Surg. 2005; 63:1072-1079

AAOMS • 2011

Oral Abstract Session 3 Abramson Z, Susarla S, Troulis M, et al: Age-Related Changes of the Upper Airway Assessed by 3-Dimensional Computed Tomography. J Craniofac Surg. 2009 Jan 29.

Evaluation of Post-Operative and PostDischarge Nausea and Vomiting in Orthognathic Surgery Patients C. Dicus: UNC-Chapel Hill, J. Arbon, T. Turvey, G. Blakey III, C. Phillips Purpose: Post-operative nausea and vomiting (PONV) is a frequent complication following general anesthesia. PONV leads to significant patient dissatisfaction and can cause delayed discharge as well as increased cost and morbidity. The only prior study of orthognathic surgery patients revealed a high incidence of PONV. This study seeks to corroborate these findings at a second institution, adding information regarding post-discharge nausea and vomiting (PDNV). To our knowledge no studies to date have examined post-discharge nausea and vomiting (PDNV) in orthognathic surgery patients. Patients and Methods: One hundred and thirteen patients, enrolled in an IRB-approved study with written informed consent and HIPAA authorization, underwent orthognathic surgery at The University of North CarolinaChapel Hill from 9/2008-12/2010. Data on PONV and potential patient-, anesthesia-, and surgery-related factors associated with PONV were obtained from the medical records. The majority of patients completed a validated post-operative diary each post-surgery day for 30 days. Sixty-one patients had an NGT overnight if a maxillary osteotomy was performed and 52 subjects who underwent maxillary osteotomies had the NGT placed and immediately removed after gastric decompression at the end of surgery. Fisher’s Exact Tests were used to assess whether the occurrence of PONV/PDNV was associated with the presence of various patient-, anesthesia-, and surgery-related factors. Level of significance was set as 5%. Results: The 61 subjects who had an overnight NGT if a maxillary osteotomy was performed all completed the post-operative diary. Of these 61 subjects, 69% were female and 66% Caucasian. Median age at surgery was 20 (IQR 17-29). 69% underwent maxillary osteotomies with or without mandibular osteotomies. According to hospital records, 61% of these 61 subjects experienced postoperative nausea. The only factor significantly related to post-operative nausea was intraoperative nitrous oxide use (48% nausea without nitrous oxide, 75% with nitrous oxide). 43% of these 61 subjects continued to experience nausea 24⫹ hours after discharge. Per hospital records, 26% of subjects experienced post-operative vomiting. Interestingly, 43% of patients reported in the diary that they had vomited while in the hospital. 23% reported episodes of vomiting 24⫹ hours after discharge. Vomiting at 24⫹ hours post-discharge was significantly more frequent in patients who had undergone AAOMS • 2011

maxillary osteotomies (31%) vs mandibular osteotomies alone (5%). Data collection is not yet complete for the other 52 subjects. Considering only subjects who had maxillary ostetotomies, 67% experienced nausea and/or vomiting post-operatively when the NGT remained in place overnight. This dropped to 50% with immediate NGT removal. Conclusions: There is a high incidence of PONV and PDNV in patients undergoing orthognathic surgery. Potential controllable risk factors for PONV are overnight placement of NGT and intraoperative use of nitrous oxide. Further studies with larger study populations to examine risk indicators for PONV/PDNV after orthognathic surgery would be valuable as we seek to develop evidence-based strategies to reduce these costly and unpleasant surgical sequelae. Supported by NIH DE 005215. References: Silva AC, O’Ryan F, Poor DB. Postoperative nausea and vomiting (PONV) after orthognathic surgery: A retrospective study and literature review. J Oral Maxillofac Surg 2006 Sep;64(9):1385-97 Phillips C, Blakey III G. Short-term recovery after orthognathic surgery: a medical daily diary approach. Int J Oral Maxillofac Surg 2008 Oct;37(10):892-6

Adverse Outcomes After Maxillomandibular Advancement for Treatment of Obstructive Sleep Apnea S. Boyd: Vanderbilt University Statement of the Problem: Several observational case series studies indicate that maxillomandibular advancement surgery (MMA) may be a clinically effective alternative therapy for patients with obstructive sleep apnea (OSA) who are unable to adhere to CPAP therapy. Surgical treatment involves inherent risks and it is essential to define the type, severity and incidence of these potential adverse outcomes to determine the risk benefit ratio of MMA for the treatment of OSA. To date the adverse outcomes of MMA have not been systematically analyzed or reported. The purpose of this study is to determine the type, severity and incidence of surgical and anesthetic adverse outcomes following MMA for treatment of OSA. Materials and Methods: This is a retrospective cohort study consisting of 76 patients who underwent MMA for treatment of OSA at Vanderbilt Medical Center between 1997 and 2007. A comprehensive systematic review of the surgical, anesthesia/recovery room and progress notes were completed for each patient to identify all perioperative complications, as well as post-operative wound healing problems. Additionally, polysomnography reports were analyzed to determine the effectiveness of MMA, as measured by changes in the apnea-hypopnea index (AHI) and low oxygen saturation after MMA. e-25