A Craniometric Analysis of the Posterior Cranial Base After Posterior Vault Distraction.

BACKGROUND: Posterior vault distraction osteogenesis (PVDO) has been demonstrated to effectively increase intracranial volume, treat increased intracranial pressure, and improve head shape in syndromic patients. The purpose of this study is to compare changes along the posterior cranial base before and after distraction. METHODS: A retrospective review was completed of subjects who underwent PVDO with computed tomography scans at 2 time-points: within 3 months preoperatively and 1 to 6 months postoperatively. Using Mimics software, craniometric landmarks were identified and surface area of the foramen magnum was calculated. A comparison of pre- to postoperative measurements was completed using Wilcoxon matched-paired signed rank tests and linear regression. RESULTS: A total of 65 PVDO subjects were identified, 12 subjects met inclusion criteria. Mean operative age was 3.0 ±â€Š4.0 years. The cranial vault was distracted on average 25.0 ±â€Š6.0 mm, with those < 12 months of age distracted 29.5 ±â€Š4.9 mm and >12 months of age distracted 22.0 ±â€Š4.9 mm (P = 0.0543). There was a significant increase in pre- to postoperative foramen magnum surface area (52.1 ±â€Š63.2 mm, P = 0.002), length (0.9 ±â€Š1.4 mm, P = 0.050), and width (0.6 ±â€Š1.0 mm, P = 0.050). Similarly, linear distances between nasion and posterior cranial base landmarks such as foramen magnum (3.4 ±â€Š4.2 mm, P = 0.010), and occipital protuberance (9.1 ±â€Š9.6 mm, P = 0.003) were increased. Subjects under 12 months had a greater percentage increases in posterior vault length than those over 12 months. CONCLUSION: Posterior vault distraction osteogenesis is associated with an increase in size of the foramen magnum, and lengthening of the posterior cranial base, both of which may be beneficial in patients with turribrachycephaly.

Craniometric Analysis of Frontal Cranial Morphology Following Posterior Vault Distraction.

BACKGROUND: Posterior vault distraction osteogenesis (PVDO) is believed to improve frontal contour in infants with syndromic craniosynostosis and turribrachycephaly. This study provides an objective craniometric analysis to determine how PVDO affects anterior cranial morphology. METHODS: A retrospective chart review of patients who underwent PVDO was performed. Inclusion criteria included pre- and postoperative computed tomography (CT) scans within 3 months before surgery and another 1 to 6 months after device removal. Volumetric and craniometric data were derived using Mimics software and compared using paired t-test and Wilcoxon rank-sum test. RESULTS: About 65 patients underwent PVDO, and 13 patients met inclusion criteria. Mean age at intervention was 3.4 ±â€Š4.2 years. Total cranial volume increased 249 ±â€Š159 cm in all patients (P = 0.0001) and 380 ±â€Š128 cm in patients younger than 1 year of age (n = 6, P =0 .0008). Supraorbital retrusion decreased from 5.44 ±â€Š3.89 to 4.54 ±â€Š3.91 mm postoperatively (P = 0.0004), decreasing significantly in patients without previous frontal surgery and not in those with previous frontal surgery (P = 0.2115; comparison P = 0.0047). Basofrontal angle decreased by 2.92 ±â€Š2.16 degrees (P = 0.0004) with a greater decrease of 3.33±2.68 degrees in those younger than 12 months (P = 0.0289) and 2.58±1.74 degrees in those older (P = 0.0079). No change was found in anterior cranial height and anterofrontal angle (P > 0.05). CONCLUSION: PVDO improves frontal contour by decreasing supraorbital retrusion and reducing frontal bossing in syndromic craniosynostosis patients with turribrachycephaly. When combined with its demonstrated efficacy for cranial expansion, these frontal changes likely reinforce PVDO's ability to influence the timing of, and to a degree, the need for frontal surgery in this group.

Spring-Mediated Cranioplasty in Sagittal Synostosis: Does Age at Placement Affect Expansion?

PURPOSE: The aim of this study is to evaluate the effect of timing of surgery and spring characteristics on correction of scaphocephalic deformity in patients undergoing spring-mediated cranioplasty (SMC) for sagittal craniosynostosis. METHODS: The authors conducted a review of patients with sagittal craniosynostosis who underwent SMC at a tertiary referral center between July 2011 and March 2017, with a primary outcome measure of head shape, both preoperatively and postoperatively, determined by cephalic index (CI). Patient demographics and operative details including timing of surgery and spring characteristics were collected. Differences in CI preoperation and postoperation were compared using Wilcoxon signed-rank test. Ordinary least-squares linear regression was used to assess the impact of timing, number of springs, maximum single spring force, and total spring force on postoperative change in CI. RESULTS: Thirty-six subjects (12 males and 24 females) were included in the study. Mean age at spring placement was 3.9 months (range: 1.9-9.2) with a mean follow-up of 1.4 years (range: 0.3-5.2). The mean number of springs used was 3 (range: 2-4). The mean maximum single spring force was 9.9 Newtons (N) (range: 6.9-13.0) and the mean total spring force was 24.6 N (range: 12.7-37.0). Mean CI increased from 70 ±â€Š0.9 preoperatively to 77 ±â€Š1.0 postoperatively (P < 0.001). Age at spring placement was significantly associated with change in CI: for every month increase in age, the change in CI decreased by 1.3 (P = 0.03). The number of springs used, greatest single spring force, and total spring force did not correlate with changes in CI (P = 0.85, P = 0.42, and P = 0.84, respectively). CONCLUSION: In SMC, earlier age at time of surgery appears to correlate with greater improvement in CI, at least in the short-term. While spring characteristics did not appear to affect head shape, it is possible that the authors were underpowered to detect a difference, and spring-related variables likely deserve additional study.