Intracranial Volume Before and After Surgical Treatment for Isolated Metopic Synostosis

Abstract

Metopic synostosis results in a keel-shaped forehead, hypotelorism, and an increased interparietal width. This study aimed to measure the frontal and total intracranial volume in patients with metopic synostosis before and after surgery and to compare the effect of 2 different operation methods. All patients operated for isolated metopic synostosis between 2002 and 2008 at Sahlgrenska University Hospital who had undergone preoperative and/or postoperative computed tomographic examination (at 3 y of age) were included. The patients were grouped according to operation method: (1) forehead remodeling in combination with a bone graft or (2) forehead remodeling in combination with a spring. Sex- and age-matched controls were identified. A previously developed MATLAB computer program was used to measure the frontal and total intracranial volumes. Sixty patients and 198 controls were included. Preoperatively, the patients with metopic synostosis had significantly lower frontal volumes than those of the controls (P < 0.001) but equal total intracranial volumes. The operations redistributed the intracranial volume and resulted in an improved, frontal-total intracranial volume ratio. However, at 3 years of age, the frontal volume (P < 0.001), total intracranial volume (P ≤ 0.002), and ratio between the 2 (P < 0.001) were significantly lower in the patients than in the controls. The 2 operation methods were equally efficient in creating an improved frontal-total ratio. Surgery for metopic synostosis improves the distribution of the intracranial volume but does not result in normal total intracranial volume or frontal volume at 3 years of age.