Making the Diagnosis in Sagittal Craniosynostosis-It's Height, Not Length, That Matters

Introduction: This study assesses the diagnostic reliability of a novel photogrammetric measurement to distinguish sagittal craniosynostosis (SS) from control and false positive cases (SNS).

Methods: Head CTs from 2014-2020 were reviewed for patients with sagittal synostosis (SS, n = 177), presumed sagittal synostosis with normal imaging (SNS, n = 30), and controls (n = 100). Using preoperative clinical photographs and CTs, a measurement reflecting the anterior-posterior location of the vertex was measured using an angle drawn between the cranial vertex, nasion, and opisthocranion (VNO) in profile view, with the head in a neutral position.

Results: Mean age at pre-operative head CT was 9.5 months for the SS cohort, 4.2 months for the SNS cohort, and 8.9 months for controls (p = .327). Mean age at pre-operative clinical photograph was 9.5 months for the SS cohort and 4.2 months for the SNS cohort (p = .149). Pearson correlations revealed no significant association between age and VNO angle. The average VNO angle measured on clinical photographs was 54.7° ± 3.8° for the SS group, 43.1° ± 2.2° for the SNS group, and 41.1° ± 3.7° for controls (p < .001). Receiver operating characteristic (ROC) analysis yielded a cut-off of ≥ 50° to identify SS. Diagnostic sensitivity and specificity were 96.6% and 99.2%, respectively. Three-rater analysis yielded an average ICC of 0.742 (p = .004).

Conclusions: Measurement of the VNO angle is a reliable screening tool to diagnose sagittal craniosynostosis, with an angle of 50° or more suggesting suture synostosis. This method relies on the relationship between the anterior displacement of the vertex and occipital bulleting to approach the diagnostic accuracy of CT imaging.