2015 HSC Section 1 Book of Articles

Research Original Investigation

Mandibular Distraction Osteogenesis

Figure 3. Proposed Treatment Algorithm for Pediatric Patients With Symptomatic Micrognathia

Severe micrognathia with symptoms of respiratory distress, unresponsive to conservative management

• Evaluation by craniofacial surgery, otolaryngology, genetics, pulmonary • Swallow evaluation • Genetic testing if indicated • Sleep study • Airway evaluation (bedside flexible endoscopy, direct laryngoscopy, bronchoscopy in operating room) • Maxillofacial computed tomography, posteroanterior/lateral cephalogram

• Nonsyndromic micrognathia • No other airway or respiratory disease • No dysphagia or aspiration

• Syndromic micrognathia (not CFM or Goldenhar syndrome) • No other airway or respiratory disease

• Syndromic or nonsyndromic micrognathia • Other airway/respiratory disease (eg, laryngomalacia, subglottic or tracheal stenosis, vocal cord paralysis, ventilator dependence) OR • Any patient with CFM–Goldenhar syndrome Tracheotomy as initial procedure with correction of other airway disease before attempting MDO as final step toward decannulation

The flowchart demonstrates our current algorithm for workup and decision making regarding the choice of mandibular distraction osteogenesis (MDO) vs tracheotomy for symptomatic micrognathia. CFM indicates craniofacial microsomia.

• No dysphagia or aspiration risk • Good neuromuscular status

• Persistent aspiration risk • Poor neuromuscular status

Proceed with MDO as initial treatment

level airway obstruction, neuromuscular compromise, and other medical comorbidities that necessitated a tracheotomy as a definitive treatment for relief of their airway obstruction. Achieving decannulation in this subgroup necessitated sig- nificantly more adjunct airway procedures, such as laryngo- tracheoplastyor endoscopic airwayprocedures, comparedwith the subgroup that underwent MDO first. The finding in uni- variable regression analysis that patients who underwent tra- cheotomy first had greater odds of a surgical complication makes intuitive sense in this context. The fact that this asso- ciationwas no longer significant in amultivariablemodel that also adjusted for thenumber of adjunct airwayprocedures sug- gests that the associationbetween initial tracheotomyandcom- plication is perhaps mediated by the need for additional pro- cedures in order to achieve decannulation. Taken together, these findings are consistent with our hypothesis that pa- tients selected for tracheotomy rather than MDO as an initial procedure were more medically complex and required more airway interventions in order to achieve a stable airway. This formof selectionbiasmayhave contributed to theirworse rates of success and complication and also creates an inherent con- founding by indication when making comparisons between these 2 subgroups (MDO first vs tracheotomy first). Limitations to our study include the retrospective nature of the data collection, lost or missing data, and the inherent confounding by indication that occurs in comparisons be- tween the MDO-first subgroup vs the tracheotomy-first sub- group. In addition, prior to 2002, when neonatal MDO be- came part of routine practice at our institution, theremay have been an even stronger selection bias toward tracheotomy as an initial procedure. To address this possibility, a secondary analysis was performed with the data set restricted to only those patients whowere treatedwithMDO after 2002, and the

Collins and CFM–Goldenhar syndromes. It is unclear why we observed such a high prevalence of these syndromes rela- tive to Stickler syndrome, but this may represent a relatively skewed population of patients who are referred from outside the local area for tertiary and quaternary care. These syn- dromes often demonstrate more severe micrognathia than in isolated Pierre Robin sequence or even other syndromic forms of micrognathia 23 and are therefore more likely to have poorer outcomes. 18 In our cohort, 4 of the 11 patients with CFM–Goldenhar syndrome and 2 of the 12 patients with Treacher-Collins syndrome had Pruzansky grade 3 classifica- tion with an absent mandibular condyle, and it is possible that thismayhavealso limited theeffectiveness ofMDO in these patients. Given thegreater percentageof these syndromes inour cohort, thismay inpart explainwhy the overall rate of success- ful MDO was slightly lower than in other published reports. Whenwe examined thepotential predictors of surgical suc- cess, the different definitions of success for the 2 subgroups (decannulation vs avoidance of tracheotomy) necessitated separate regression analyses based on initial intervention (tra- cheotomy first vs MDO first). Thus, we cannot draw conclu- sions regarding predictors of success across both subgroups. However,we can reasonably conclude that amongpatientswho required a tracheotomy as an initial procedure, patients with CFM–Goldenhar syndrome seem to have a far worse chance of success with subsequent MDO than patients with isolated Pierre Robin sequence. This association does not seemto hold among patients who underwent MDO first in the absence of a tracheotomy. Compared with patients treated with MDO first, those treated with tracheotomy first had significantly more syn- dromic diagnoses andwere older at the time of MDO. Many of these patients had additional comorbidities, such as multi-

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

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