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Discussion: Retrospective Review of the Complication Profile Associated with 71 Subcranial and Transcranial Midface Distraction Procedures at a Single Institution.

www.PRSJournal.com 531 Z et al.1 present an 18-year retrospective analysis of complications following distraction surgery for midface hypoplasia by three surgeons at a single institution. Their findings of increased complication percentage in transfacial compared to subcranial procedures adds to our literature,2–9 but their large series also raises the interesting question of whether there exists an ideal ratio of transcranial to subcranial operations in a center prioritizing staged treatment of syndromic synostosis. The authors report on 26 patients who underwent transcranial distraction at an average age of 5.8 years (range, 3.7 to 14.7 years), and 38 patients who underwent subcranial distraction at an average age of 7.5 years (range, 3.6 to 18.7 years). The authors state they chose transcranial surgery for patients with combined brow and midface retrusion, whereas they chose subcranial surgery for isolated midface hypoplasia. Six of the transcranial cases and one of the subcranial patients subsequently underwent subcranial distraction at an average age of 14.7 years, presumably for treatment of malar hypoplasia with facial growth. The authors report a 58 percent transcranial complication rate, 80 percent of which were infectious in origin, and two patients required intensive care unit level treatment for sepsis. In comparison, the subcranial group had a 29 percent complication rate, 54 percent infectious in origin, with none requiring intensive care unit level treatment. They also confirmed the findings of others7,8 of a relatively increased blood transfusion volume and surgery time in the transcranial group. This potential increased complication risk in transcranial surgery has led some centers to advocate staged treatment of syndromic craniofacial retrusion, with a fronto-orbital advancement in infancy and a subcranial advancement in adolescence,10–12 reserving primary transcranial monobloc procedures for severe phenotypes that justify the risk.3 Although it is outside the purpose of this article, it would be of interest to know what proportion of the transfacial group in the series reported by Zhang et al. differed from the subcranial group because of a distinct severe presenting phenotype, and what proportion differed instead by a relapse response to earlier frontal surgery. With a 40 percent (26 of 64) transcranial treatment rate in the article by Zhang et al., it would be of value for future comparison studies to know how many of these were primary early monobloc osteotomies (distinct severe presenting phenotype), and how many had previous fronto-orbital advancements but with relapse (same presentation as the subcranial group, but differential response to previous surgery). This distinction is important to our ongoing debate on syndromic treatment, and the interpretation of case series such as this one. Ideally, a center advocating staged treatment would be able to identify accurately the severe phenotypes that would benefit the most from primary monobloc osteotomies, and then achieve a stable first-stage fronto-orbital advancement in the remaining majority, so that only subcranial retrusion and the need for a subcranial operation remains by adolescence. In this ideal state, what should the transcranial-to-subcranial ratio of a large midface series be? Would it be the 2:3 observed by Zhang et al. over 18 years, or should centers advocating staged treatment be working toward a lower transcranial component? The relapse risk following fronto-orbital advancement in syndromic cases is well recognized,13 but what is not yet known is whether this risk is inevitable (should we just accept that some patients will