Postnatal Diagnosis of Single-suture Craniosynostosis with Cranial Ultrasound

Background: The optimal protocol for diagnostic workup of craniosynostosis and the role of specific imaging modalities remain controversial. 3-dimensional head CTs, the gold standard, and skull X-rays and are traditional options when physical exam is equivocal, but their routine use is controversial due to the potential need for sedation and the long-term risks of ionizing radiation in pediatric patients. Ultrasound has emerged as an alternative modality for visualization of cranial sutures since it involves neither sedation nor radiation. Despite these advantages, ultrasound has not been widely adopted yet as a diagnostic tool for single-suture craniosynostosis. The goal of this study is to perform a systematic review and define the sensitivity and specificity of ultrasound for the diagnosis of non-syndromic single-suture craniosynostosis and identify potential pearls and pitfalls. Our findings may help pediatricians, particularly pediatric neurosurgeons and craniofacial specialists, incorporate ultrasound into diagnostic pathways for patients with suspected craniosynostosis to avoid the aforementioned barriers that may otherwise delay diagnostic imaging and evaluation.

Methods: Using the PubMed, Scopus, and Springer Link databases, the authors performed a systematic review of the literature on the use of ultrasound for the diagnosis of craniosynostosis, which is detailed in an according PRISMA diagram (Figure 1). Studies assessing syndromic craniosynostosis and prenatal imaging were excluded. Two independent reviewers assessed the search results and performed data abstraction.

Results: A total of 12 studies involving 1,062 patients were included (Figure 2). The mean or median patient age across studies ranged from 4.2 to 7.8 months. Overall, 300 patients (28.2%) were diagnosed with craniosynostosis. A total of 369 (34.7%) patients had their diagnosis (craniosynostosis vs. patent sutures) confirmed with another imaging modality in addition to ultrasound. Among studies, the specificity of ultrasound ranged from 86% to 100%, and the sensitivity from 71% to 100%.

Conclusion: Ultrasonography of cranial sutures is a feasible and accurate tool for the diagnosis of single-suture craniosynostosis when physical exam findings are insufficient. However, several limitations must be acknowledged, including inter-evaluator variability based on the experience of the technician. Ultrasonography of the cranial sutures has a learning curve, and some studies identified false positives during their initial evaluations. False positives are likely due to the ultrasound probe being incorrectly centered over an adjacent region of intact calvarium rather than the suture itself and may occur when the sonographer is unfamiliar with the expected course of the suture. Simulators designed for training purposes have been shown to increase diagnostic accuracy. Although technical aspects of ultrasonography and its interpretation have an associated learning curve, ultrasound can achieve a high sensitivity and specificity among patients with suspected craniosynostosis. Patients do not require sedation and ionizing radiation is not involved, making cranial ultrasound a safe and attractive alternative to skull X-rays and/or head CTs.