Anterior fontanelle closure and diagnosis of non-syndromic craniosynostosis: a comparative study using computed tomography

Abstract

Objective: Suspicion of early anterior fontanel (AF) closure is a common reason for referral to a pediatric neurosurgeon because of the suspected increased risk of developing craniosynostosis (CS) in spite of the absence of evidence in the literature. The aim of this study was to analyze the association between AF closure and the diagnosis of non-syndromic CS in Brazilian children.

Methods: An observational and case-cohort study was conducted to compare the incidence of closed AF between healthy children (group 1) and children diagnosed with non-syndromic CS (group 2) at a pediatric neurosurgery referral center. The accuracies of completely closed AF and diagnosis of CS were assessed.

Results: High-resolution three-dimensional reconstruction computed tomography scans were obtained for 140 children aged < 13 months, of whom 62.9% were boys and 37.1% were girls (p < 0.001). The most common types of non-syndromic CS were trigonocephaly (34, 48%) and scaphocephaly (25, 35.7%). Closed fontanel (27, 38.6%) was observed in both groups, and a sensitivity of 36.1%, specificity of 72%, the positive predictive value of 59%, and negative predictive value of 51% were observed in the patients diagnosed with CS when AF closure occurred before the age of 6 months.

Conclusion: The results of this comparative study of AF closure and CS diagnosis suggest that early AF closure does not imply a diagnosis of CS. Pediatricians should be aware of the risk of misdiagnosis of CS in cases with a widely open AF in spite of the presence of CS.

Keywords: Anterior fontanel; Computed tomography; Craniosynostosis; Growth and development; Suture.

Figure 1

Computed tomography image with three-dimensional reconstruction of the skull in healthy children. The anterior fontanel could be opened (thick black arrow; left) or closed or fused (thin black arrow) in a 4-month-old boy (right).

Figure 2

Computed tomography image with three-dimensional reconstruction of the skull image in children with non-syndromic craniosynostosis, demonstrating that anterior fontanel (AF) could present as open (thick black arrow) or closed (thin black arrow). (A) A widely open AF is depicted in patients with (A) scaphocephaly and (B) trigonocephaly or (C) a completely fused AF in scaphocephaly and (D) trigonocephaly. The metopic suture is fused in trigonocephaly (*). The sagittal suture is fused in the scaphocephaly (arrowhead).