Facial Nerve Dysfunction After Mandibular Distraction Osteogenesis in Patients with Robin Sequence: A Systematic Review and Meta-Analysis

Objective Robin Sequence (RS), characterized by micrognathia, glossoptosis, and upper airway obstruction, is an increasingly recognized diagnosis. An effective surgical intervention is mandibular distraction osteogenesis (MDO). This study analyzes published evidence regarding facial nerve dysfunction (FND) associated with MDO. Design and Setting According to PRISMA guidelines, a systematic review was carried out with databases queried in June 2019 using MESH terms, or equivalent terms, as follows: “distraction osteogenesis” and “Robin Sequence”. A review of original Spanish and English articles, were included. Outcome measures included the prevalence of FND; the affected branches; the rate of permanent vs. transient FND; the use of an internal vs. external device; the daily distraction rate; and finally, the overall distraction length. Subsequently, a meta-analysis was conducted to collate results regarding the prevalence of FND and the factors associated with it. Results Of 239 unique studies identified, 19 studies with 729 patients met inclusion criteria; 52 patients developed FND after MDO. A random-effects meta-analysis yielded a pooled prevalence of FND of 6.40%, with moderately heterogeneous studies (I2 = 41%, τ2 = 0.006). Marginal mandibular nerve involvement was most commonly noted. Nine studies reported transient FND, six permanent, one both, and two unspecified. Internal distractors were used in 8 studies and external in 3 and both in 2. Distraction rate was 1.00 to 2.00 mm/day and total distraction length ranged from 13.00 to 22.3 mm. Sample size was the only parameter inversely associated with rate of FND (p = 0.04). Conclusion This analysis of FND associated with MDO for patients with RS demonstrates a lack of consistent documentation. MDO-associated FND does not appear to be uncommon, and permanent dysfunction can occur. This review underscores the importance of thorough documentation to elucidate the mechanism of FND.

The Radiographic “Air Sign” in Neonatal Mandibular Distraction Osteogenesis

Timing of extubation on post-mandibular distraction osteogenesis (MDO) surgery is critical, given that at baseline these infants have difficult airways and failed extubation requires either re-intubation of an already complex airway with a fragile, recently osteotomized mandible, or adjunctive airway measures such as CPAP that may apply unwanted pressure to the surgical site. Thus, the goal is to plan extubation when the risk of failure is minimal. Currently, there is a void in the literature addressing the timing of extubation post-MDO and no objective sign of extubation readiness has been elucidated. This study describes a simple clinical pearl to assist in the evaluation of extubation readiness in these patients. Postoperatively, we obtain weekly radiographs to assess distractor stability and advancement, and to assess for the “Air Sign”. The Air Sign describes a radiolucent space (air) visualized in the oropharynx on lateral radiographs, likely indicating that the tongue based airway obstruction has been relieved by mandibular advancement.