title: Three-dimensional computed tomography in obstructive sleep apneics treated by maxillomandibular advancement.
abstract: OBJECTIVE
  The goal of this study was to understand the changes to the head and neck musculoskeleton and the pharyngeal airway after surgery. We tested the correlation between the changes in the skeleton and pharyngeal airway and the apnea-hypopnea index (AHI).
  
  
  METHODS
  Prospective, noncontrolled study.
  
  
  METHODS
  In a pilot study, 12 consecutive subjects (3 women, body mass index: 22.4 Kg/m(2) ± 2.7, AHI: 35.9/sec ± 18.0) with Class II dentoskeletal malocclusion and high mandibular plane underwent segmental maxillomandibular rotational advancement (SMMRA). Subjects underwent overnight polysomnography and three-dimensional computed tomography scanning of the head and neck before and 3 months after surgery. Linear, angular, and area measurements were obtained from skeletal images placed in the Frankfort horizontal position and from horizontal cross-sectional tomograms derived from the upright pharyngeal airway. Skeletal movements, dimensional changes of the airway, and correlations between measurements and AHI were calculated. A linear regression model was generated using significant bivariate correlations.
  
  
  RESULTS
  The AHI was significantly reduced to 4.6/sec ± 4.1 with improvement in the nadir oxygen saturation from 83.0% ± 7.2 to 90.6% ± 3.6 after SMMRA. Following skeletal advancement, the hyoid bone was advanced and elevated by 7.5 mm ± 2.9 and 6.7 mm ± 5.5, respectively; the cervical spine was rotated forward by 4.6° ± 2.8; and the airway length was shortened by 6.8 mm ± 4.0 (all P < .01). Variable improvement of airway dimensions was noted at each horizontal level. A quadratic regression model was derived using the measurements of the Sella-Nasion-B point angle and AHI (Rsq = 0.557, sig = 0.000).
  
  
  CONCLUSIONS
  Dimensions of pharyngeal airway were correlated with dimensions of craniofacial skeleton. Sella-Nasion-B point angle could be used as a guidance in achieving normalized AHI after surgery.
authors.affiliation: Craniofacial Center, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan. clementlin0614@gmail.com
authors.forename: Cheng-Hui
authors.initials: CH
authors.lastname: Lin
authors.forename: Yu-Fang
authors.initials: YF
authors.lastname: Liao
authors.forename: Ning-Hung
authors.initials: NH
authors.lastname: Chen
authors.forename: Lun-Jou
authors.initials: LJ
authors.lastname: Lo
authors.forename: Yu-Ray
authors.initials: YR
authors.lastname: Chen
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D019186:Mandibular Advancement / Q000379:methods; D008437:Maxilla / Q000601:surgery*; D011446:Prospective Studies; D020181:Sleep Apnea, Obstructive / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult