Epidemiology of Rare Craniofacial Anomalies: Retrospective Western Australian Population Data Linkage Study

OBJECTIVE

To describe birth prevalence of rare craniofacial anomalies and associations with antenatal and perinatal factors.

STUDY DESIGN

All live and stillbirths in Western Australia between 1980 and 2010 were identified from the Western Australian Birth Registrations and the Midwives Notification System (also provides information on antenatal and perinatal factors). Rare craniofacial anomalies (craniosynostosis, craniofacial microsomia, and others [Pierre Robin, Van der Woude, and Treacher Collins syndrome]) were ascertained from the Western Australian Register of Developmental Anomalies and linked to other data sources. Trends in prevalence, adjusted for sex and Indigenous status, were investigated by Poisson regression and presented as annual percent change (APC). Strengths of association of related factors were assessed using multivariable log-binomial regression adjusted for sex, Indigenous status, birth year, socioeconomic disadvantage, and remoteness and reported as risk ratios with 95% CIs.

RESULTS

There was a temporal increase in prevalence of metopic synostosis (APC 5.59 [2.32-8.96]) and craniofacial microsomia (Goldenhar syndrome) (APC 4.43 [1.94-6.98]). Rare craniofacial anomalies were more likely among infants born preterm, as twins or greater-order multiples, with growth restriction, to older parents, to mothers undertaking fertility treatments, and with pre-existing medical conditions, specifically epilepsy, diabetes, or hypothyroidism. Prenatal identification of rare craniofacial anomalies was uncommon (0.6%).

CONCLUSIONS

Our findings indicate a steady increase over time in prevalence of metopic synostosis and craniofacial microsomia (Goldenhar syndrome). Possible associations of fertility treatments and pre-existing maternal medical conditions with rare craniofacial anomalies require further investigation.

Antenatal Ultrasound Imaging for Analysis of Human Craniosynostosis

The cranial sutures can be imaged sonographically in the fetus as early as the end of the first trimester; however, fetal position and maternal body habitus can present significant challenges to clear visualization. Antenatal identification of craniosynostosis is important for delivery planning, and there are a number of available ultrasound techniques and imaging signs to assist with accurate diagnosis of both single suture craniosynostosis and syndromic multisutural fusions.

The Normal Fetal Cephalic Index in the Second and Third Trimesters of Pregnancy

The cephalic index (CI) is used in the evaluation of individuals with craniosynostosis. There is little agreement as to the normal range and stability of the CI during the fetal period, partly due to limited literature. We sought to determine the range, distribution and stability of the fetal CI in the second half of pregnancy. We also aimed to identify any relationship to delivery complications such as obstructed labor and malpresentation.The fetal head circumference, biparietal diameter (BPD) and occipitofrontal diameter (OFD) measurements were obtained from standard ultrasound images. Each of 4304 fetuses had measurements taken at morphology scan performed between 17 and 22 weeks' gestation, and at growth scanning at 28 to 33 weeks' gestation. The cephalic index was calculated using the formula: CI = BPD/OFD × 100. The distribution of the CI at both scans is very close to a normal distribution. The mean CI at 17 to 22 weeks was 75.9 (SD, 3.7); the mean CI at 28 to 33 weeks was 77.8 (SD, 3.5). The mean change in CI was 1.9 (SD, 4.28), which is not statistically significantly different from zero (t = 0.656, P = 0.512, 95% confidence interval). No relationship was found between the CI in normal fetuses and delivery complications. There is a wide variation in the change in CI in the third trimester. A value below the normal range in the third trimester or a progressive reduction in CI during the latter half of pregnancy should provoke detailed scanning of the fetal cranial sutures to check for craniosynostosis.

Sonographic indicators of isolated fetal sagittal craniosynostosis during pregnancy

INTRODUCTION

The antenatal diagnosis of sagittal craniosynostosis can be challenging, but there are several published papers describing a traumatic outcome to both the affected fetus and the mother during delivery of a scaphocephalic child. The antenatal imaging from affected children was collected along with the mother's obstetric history. The aim of this study was to identify antenatal ultrasound features that may assist the diagnosis of sagittal synostosis before birth, to enable appropriate delivery planning and avoid both maternal and fetal trauma during birth.

METHODS

Antenatal ultrasound scans in both the second and third trimesters were traced for 36 children with sagittal synostosis. The initially diagnostic CT scans were also sourced. A delivery history was collected from the hospital case notes where available.

RESULTS

The affected group showed a statistically significant reduction in cephalic index during the second half of pregnancy compared with the normal population which became slightly more brachycephalic (P = 0.001). Regression analysis showed an average reduction in cephalic index of 0.57 units per month. There was also a much higher rate of malpresentation and surgical deliveries in the affected group than the normal population. There was a relationship between sagittal craniosynostosis and breech presentation and an associated higher rate of surgical deliveries.

CONCLUSION

It is possible to detect sagittal synostosis in the third trimester of pregnancy which may assist with delivery planning.