2015 HSC Section 1 Book of Articles

Original Investigation Research

Mandibular Distraction Osteogenesis

P ierre Robin sequence is characterized by the triad ofmi- crognathia, glossoptosis, and resultant airway obstruc- tion owing to constriction of the retrolingual space. 1 Though not classically described as part of its definition, cleft palate is a commonly associated finding that occurs in up to 90%of childrenwith Pierre Robin sequence. Symptoms of air- way obstruction may range from snoring and stertor while asleep to frank obstruction and retractionswhen awake. Gasp- ing or aspirationwhile feeding is frequently encountered, and this in combinationwith chronic airway obstruction can cause failure to thrive. Long-termsequelae of severe airway obstruc- tion can lead to cor pulmonale and cardiorespiratory arrest. Interventions aimed at relieving such symptoms vary de- pending on the severity of the symptoms. Conservative mea- sures for less severe symptoms include prone positioning and use of a nasopharyngeal airway. 2 In the event that such con- servative treatments areunsuccessful or formore severe symp- toms, options for surgical intervention include tongue-lip ad- hesion, tracheotomy, andmandibular distractionosteogenesis (MDO). Tongue-lip adhesion has been shown to significantly improve obstructive sleep apnea due tomicrognathia 3 but has generally been less effective thanMDOat normalizing obstruc- tive symptoms, particularly in severely symptomatic pa- tients. In addition, tongue-lip adhesion can lead to dysphagia and feeding difficulties. 4 Tracheotomy offers a definitive treat- ment for upper airway obstruction but has associated risks of accidental decannulationormucous plugging. There is alsopo- tential long-termmorbidity related to peristomal scarring and tracheal erosion in addition to the need for long-term main- tenance and home care. 5,6 In recent years, there have been an increasing number of reports on the results of MDO as an al- ternative to tracheotomy. 7-15 The goals of this study were to assess the surgical success and complication rates of MDO for treatment of severemicro- gnathia and to identify potential predictors of surgical suc- cess and complications. Surgical successwas defined as either (1) avoidance of tracheotomy or (2) decannulation among those patients treated initially with a tracheotomy. This was a retrospective cohort study of all patients who un- derwent MDO from September 1, 1995, to December 31, 2009, at Cincinnati Children’s Hospital Medical Center. Inclusion cri- teria included any patients who underwent initial MDO dur- ing the study period. All patients were seen through a multi- disciplinary craniofacial clinic, and those with a concern for syndromic Pierre Robin sequencewere routinely evaluated by clinicians from both the genetics and ophthalmology depart- ments in addition to the craniofacial surgery and otolaryngol- ogy departments to ensure proper diagnosis and manage- ment. Electronic and paper chart medical records were reviewed for relevant data. Patients who were lost to fol- low-up afterMDOor had incompletemedical records were ex- cluded. Mandibular distraction osteogenesis was performed with short sagittal split osteotomies using primarily external Methods Participants

distractiondevices, although internal distractiondeviceswere used inaminorityof patients basedonsurgeonpreference. This study was approved by the institutional review board of Cin- cinnati Children’s Hospital. Potential Predictors Variables included as potential predictors of outcome in- cluded demographics (sex, age at time of distraction), fol- low-up time, syndromepresence (categorizedas isolatedPierre Robin sequence, craniofacial microsomia [CFM] or Golden- har syndrome, Treacher-Collins syndrome, and other syn- dromes), type of initial surgical intervention (tracheotomy vs MDO), length of mandible distracted, number of distractions, and number of subsequent airway procedures (eg, laryngo- tracheoplasty, endoscopic airway procedures, base of tongue procedures, choanal atresia repair). Outcomes While the primary goal of MDO was to improve the retrolin- gual airway and relieve airway obstruction, the definition of surgical success necessarily differed for patientswhowere ini- tially treated with tracheotomy prior to MDO compared with thosewho underwent MDO as an initial procedure. Thus, sur- gical success was defined as (1) avoidance of tracheotomy among patients who were treated first with MDO and (2) suc- cessful decannulation among patients who initially under- went tracheotomy prior to MDO. Complications assessed in- cluded open bite deformity, premature bone consolidation, temporomandibular joint (TMJ) ankylosis, facial nerve in- jury, emergent reintubation, andprolonged intubation. For the purposes of this analysis, the need for repeated distraction more than 30 days after the initial distractionwas not consid- ered a complication because it was felt that this need re- flected a lack of innate growth of the distractedmandible over time rather than a failure of the initial distraction. Statistical Analysis Descriptive statistics are reported as means (SDs) and medi- ans with interquartile ranges (IQRs) or frequencies with per- centages. The characteristics of the 2 subgroups defined by ini- tial surgical treatmentwere comparedusing theWilcoxon rank sum test for continuous variables and the χ 2 or Fisher exact test for categorical variables. Logistic regression analysis was used to assess the relationship between the potential predic- tors and each dichotomous outcome of interest (surgical suc- cess and occurrence of complications). The analysis of surgi- cal success was stratified by initial surgical intervention (tracheotomy vs MDO), since the definition of outcome dif- fered between these subgroups. For potential predictors of a complication, all complicationswere grouped together as a di- chotomous outcome (any complication or no complication). The entire cohortwas included in this regression analysis since the definition of a complicationwas the same regardless of the initial intervention. For eachoutcome (surgical success andoc- currence of a complication), logistic regression models were constructed to identify potentially important associations be- tween the predictor variables and each outcome of interest. A conservative criterion P = .20was used as a cutoff for inclu-

JAMA Otolaryngology–Head & Neck Surgery April 2014 Volume 140, Number 4

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