A Comparison of Intracranial Volumes and Metopic Index in Patients With Isolated Metopic Ridge, Metopic Craniosynostosis, and Normal Healthy Children.

Abstract

Previous research has shown that patients with metopic craniosynostosis have significantly reduced intracranial volumes (ICVs) compared to normal healthy children. Furthermore, the metopic index (ratio of midfrontozygomatic diameter to maximal cranial width) has been described as an anthropometric cranial index for patients with metopic craniosynostosis. We aimed to determine whether patients with isolated metopic ridge have significantly different ICVs or metopic indices than normal children and patients with metopic craniosynostosis. A retrospective chart review of all patients with a diagnosis of a metopic ridge or metopic craniosynostosis was performed from 2000 to 2015 at Rady Children's Hospital. Patients were grouped based on computed tomographic scans consistent with metopic craniosynostosis versus metopic ridge. Data were available for 15 metopic ridge patients, 74 metopic craniosynostosis patients, and 213 normal patients. Mean metopic ridge ICV was greater than mean metopic craniosynostosis ICV at 4 to 6 months and 7 to 12 months. Controlling for age and sex, the difference in ICV associated with metopic ridging was 197.484 cm3 and 137.770 cm3 at 4 to 6 and 7 to 12 months, respectively. Similarly, mean metopic index was significantly greater in metopic ridge patients compared to mean metopic craniosynostosis at 4 to 6 months and at 7 to 12 months. Our study provides volumetric and anthropometric data to support the hypothesis that isolated metopic ridge is an intermediate phenotype between metopic craniosynostosis and normal cranial anatomy. We hope that characterizing the spectrum of disease involving premature closure of the metopic suture with regard to ICV and metopic index will aid physicians in their management of patients with isolated metopic ridge.