Head Circumference is Relatively Larger Than Size: A Novel Screening Tool for Infants With Sagittal Craniosynostosis

Background: The efficacy of minimally invasive techniques for addressing isolated sagittal craniosynostosis decreases with age; thus, timely referral is critical. We sought to identify a screening tool using data from well-child visits. We hypothesized that many infants with sagittal craniosynostosis, but no macrocephaly based on growth chart plotting, in fact have a relative macrocephaly. Methods: All infants with CT and surgically/pathologically confirmed isolated sagittal craniosynostosis were identified. Growth chart data was collected (head circumference (HC), weight, crown-to-toe-length, and World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) percentiles and deviation ( z-scores)). Relative macrocephaly was defined as head circumference >2SD from size (weight and/or length). Results: Initial pilot screen indicated that WHO growth chart data has utility as a screening tool. Subsequent retrospective case-control study with area under the curve (AUC) analysis revealed that HC:length ratio ≥0.71 is indicative of isolated sagittal craniosynostosis as young as 1 week of age, while HC:length ratio ≥0.67 represents the maximization of sensitivity (0.89) and specificity (1.00) as early as 2 weeks old. Prospective internal validation with logistic regression demonstrated that at ages 1 to 2 months greater discriminatory value HC:length ratio was observed. Conclusions: When length is added to head circumference as a screening tool we may identify an abnormal growth pattern beginning as early as 1 week. This represents an opportunity to design an automated alert easily programed into the electronic medical records and may prompt pediatricians to refer patients to craniofacial surgeons early.