The Degree of Surgical Frontal Volume Correction in Metopic Synostosis Determines Long-Term Outcomes

Metopic synostosis results in a keel-shaped forehead, reduced frontal intracranial volume (ICV), and lower frontal to total volume ratio. The ratio improves with cranioplasty, but at 3 years of age, the ratio is still not normalized when compared to that in normal children. The aim of the present study was to investigate whether a low frontal to total ICV ratio at 3 years of age was due to relapse or insufficient correction.All children surgically treated for metopic synostosis in combination with a spring at Sahlgrenska University Hospital with subsequent spring extraction between 2002 and 2008 (n = 20) were included. A MATLAB program was used to measure frontal and total ICV.Preoperatively, the frontal to total ICV ratio was 9.8 ± 1.3% (mean ± standard deviation). At spring removal, 6 months after cranioplasty, the ratio had increased to 11.8 ± 2.4%. At 3 years of age, the ratio was 11.6 ± 1.9%. In age-matched normal children, the ratio was 14.4 ± 1.9% preoperatively, 15.3 ± 2.2% at time of spring extraction, and 13.4 ± 1.4% at 3 years of age.Cranioplasty thus improved the frontal to total ICV ratio, but did not normalize it. The ratio did not change from 6 months after the cranioplasty to 3 years of age. These results indicate that a more pronounced frontal volume correction during cranioplasty is necessary to achieve a normalized distribution of ICV in metopic synostosis.