After evaluating the majority of the research available and discussing these studies with some experts in the field, we have found that the following timeline is an appropriate average that can provide some clarity to the families that have these questions.
Please note that some studies have indicated that suture closure may not be controlled by age but may be related to other biological factors not yet understood due to lack of research available. It is important to also note that the obliteration of skull sutures has never been a reliable tool of age indication, thus telling us that these numbers may or may not accurate.
It is important to note that the skull is divided into two distinct portions; the neurocranium which surrounds the brain and the viscerocranium which form the lower face and jaws. The neurocranium is further divided into the membranous neurocranium and the cartilaginous neurocranium. The term premature cranial suture synostosis signifies premature closure of one or more of the cranial sutures. Altered skull shape is diagnostic and in most cases, will be the primary indicator of Craniosynostosis. Because Craniosynostosis does not always occur across the entire length of the suture, or involve the entire depth of the suture, some instances of Craniosynostosis and whether or not surgical intervention may be necessary are open to interpretation.
Some of the information on the internet may be difficult for one to understand. Fusion of a suture, premature fusing of a suture(Craniosynostosis) and full obliteration of a suture have varying definitions when one is considering what may be “normal” or “abnormal” in terms of age and suture closing.
It is also important to note that numbers vary due to what exactly defines suture fusing.
Metopic Suture: The Metopic suture which runs mid-line of the frontal bone will fuse normally with no skull defect between the ages of three(3) months of age and nine(9) months of age.
Sagittal Suture: Full obliteration may never occur. The suture closes sometime between the ages of 30 years old and 40 years old. The suture has been seen to close normally at age 26 and also remain open until someone in their late 50’s.
Coronal Sutures: Suture may begin to fuse by the age of 24. Average Suture closes between the ages of 30 years old and 40 years old.
Lambdoid Sutures: Full obliteration may never occur. Suture closes normally between the ages of 30 and 40 years old.
Squamosal Sutures: Sutures close between 30 and 40 years of age.
Frontal Sphenoid: May close normally by the age of three(3) months old.
The timing of when exactly a suture will permanently obliterate is still a hot topic. There are varying degrees of closure and timing is yet to be clearly defined. Abnormal head shape is the most reliable indicator of a skull defect and along with some radiographic studies, an experienced surgeon will be able to make a definitive diagnosis of your child and whether or not surgery is required.
This information may not be accurate and is an interpretation of many studies.