A Craniometric Analysis of Posterior Cranial Vault Distraction Osteogenesis

Background: Posterior cranial vault distraction osteogenesis has replaced fronto-orbital advancement in some centers as the first-line treatment in patients with syndromic craniosynostosis. Despite this fact, little has been written about its craniometric effects on children with syndromic craniosynostosis. Methods: A retrospective review of all patients who underwent posterior distraction was performed. Patient demographic, perioperative data, and preoperative/postoperative computed tomographic scans were reviewed. Volumetric and craniometric indices were calculated and measured using commercial three-dimensional imaging software. Results: From 2008 to 2012, 22 patients underwent posterior vault distraction osteogenesis for suspected intracranial hypertension or severe turribrachicephaly. In 13 patients, this was the first cranial vault procedure performed, whereas eight had previous fronto-orbital advancement and one had parieto-occipital reshaping. Half of patients underwent posterior cranial vault distraction osteogenesis before age 1 year; the average age at surgery was 2.3 years (range, 0.3 to 14.1 years) and distraction length averaged 27.3 mm (range, 19 to 35 mm). Average length of surgery was 2.9 hours (range, 1.6 to 3.8 hours), and average blood loss was 400 ml (range, 200 to 600 ml). Total treatment length was 91 days (range, 48 to 147 days). Distraction length averaged 27.3 mm (range, 19 to 35 mm). Intracranial volume increase averaged 21.5 percent (range, 7.5 to 70.0 percent; p < 0.0001) and 28.4 percent (range, 10.8 to 66.0 percent; p = 0.01) in the subset of patients younger than 1 year. Posterior cranial height increased 12.2 percent (range, 0 to 35 percent; p = 0.002), and basofrontal angle decrease averaged 3.9 percent (range, 0 to 12 percent; p = 0.003), indicating a decrease in cranial height trajectory and improvement in frontal bossing. Conclusions: Posterior cranial vault distraction is a safe and effective operation that may lower risk of intracranial hypertension and abnormal skull morphology. Interestingly, cranial morphological benefits were seen both anteriorly and posteriorly.