When babies are born, their skull consists of six plates designed to partially overlap with one another, which allows the head to temporarily contract and fit through the birth canal. As the brain grows and expands over the first several months of life, the plates eventually slide back out and flatten. The edges of the plates come together in joints (called sutures) and allow for the rapid growth of the brain over the first two years, and eventually begin to close (fuse). As these sutures close and the cranial bones harden, there is less opportunity for cranial growth.
During these first two years, the child's skull is soft and vulnerable, leaving them at risk for developing abnormal head shapes. If left untreated, these abnormalities can lead to other medical issues later in life.
There are typically three main causes of abnormal head shapes:
This group makes up the largest number of infants with an abnormal head shape; these abnormal head shapes usually develop during pregnancy or while the baby is sleeping.
The most common head shape anomaly is positioning-related flattening, sometimes called positional plagiocephaly, a disorder in which the back or one side of an infant's head is flattened. Sometimes this is more prominent on one side, with a bulge on the other side. There can also be an offset to the ears when viewed from the top. This asymmetry is caused when too much pressure is placed on one side of the head. Also, pediatricians have noted an increase in infants whose heads are flattened in the back since the “Back to Sleep” campaign was initiated in 1994 to prevent sudden infant death syndrome.
A variety of factors may be involved in positional plagiocephaly. The most common factors are:
Called craniosynostosis, this is the next most common group of infants with abnormal head shapes. This condition is a rare kind of flattening and occurs when one or more of the joints between the cranial plates close prematurely. As the brain continues to grow, it forces the remainder of the skull to expand out of proportion, leading to an abnormal shape. Left untreated, craniosynostosis may also cause damage to the infant's brain.
The smallest group is infants with craniofacial syndromes, such as Apert's and Crouzon's. These children have craniosynostosis and facial bone abnormalities along with other deformities.
Early evaluation and possible intervention are important to the successful management of head and facial abnormalities. The decision to seek evaluation and possible treatment should be made as early as possible.