Plagiocephaly is a term used to describe an asymmetric head shape.
The word itself comes from the Greek plagios (oblique or slanted) and kephale (head). It is important to identify the type of plagiocephaly which is classified into:
1. Frontal (anterior) plagiocephaly, caused by unilateral synostosis of the coronal suture
2. Occipital (posterior) plagiocephaly, caused by unilateral synostosis of the lambdoid suture
Frontal (anterior) plagiocephaly
This condition occurs with premature closure of one coronal suture on one side of the skull. The resulting deformity does not only affect the skull, but it also results in under development of the ipsilateral frontal bone (forehead), supraorbital ridge (eyebrow) and anterior cranial fossa, giving a flattened appearance. The pathological changes also extend to involve the base of the skull resulting in lower facial deformity. This disorder is not congenital, does not have a genetic basis and is usually not associated with raised intracranial pressure.
A characteristic skull deformity is noted where the frontal bone is depressed on the affected side giving the normal side a false appearance of a bulging forehead. The supraorbital ridge is also underdeveloped and deviated backward and upward and there is a lower face twist causing a “winking” effect. The ipsilateral ear is usually situated more anterior and inferior than normal.
Posterior (occipital) plagiocephaly
The two predominant causes of posterior plagiocephaly are craniosynostosis (<2%) or positional molding (vast majority) of the lambdoid suture. This results in the flattening of the ipsilateral parietooccipital region. Positional (deformational) plagiocephaly refers to a misshapen (asymmetrical) shape of the head resulting from external repeated pressure to the same area of the head over a relatively long period of time causing a baby’s head shape to be abnormal but with no real fusion of the skull sutures. The condition has become more common since the American Academy of Pediatrics recommended that infants sleep on their backs to reduce the incidence of sudden infant death syndrome (SIDS).
Causes of positional plagiocephaly include prematurity, torticollis and cervical spine abnormalities. It is usually managed using non-surgical techniques except in severe persistent cases.
True lambdoid synostosis (posterior plagiocephaly) is a very rare form of craniosynostosis and is commonly mistaken for positional plagiocephaly. In true lambdoid synostosis, the lambdoid suture is fused. This gives the affected side a flattened appearance along the back of the head and when looking down at the patient, the ear on the affected side is pulled back toward the involved suture. The forehead is usually not affected as severely but may appear flattened. In contrast, with positional plagiocephaly, the backside of the head is flat but the ear is pushed forward and the forehead on that same side appears full. Additionally, in deformational plagiocephaly, the skull shape abnormality may not have been present at birth and may improve over time, while in posterior plagiocephaly,
due to the true synostosis of the lambdoid suture, the deformity is present at birth and worsens with time. Torticollis, prematurity and cervical spine abnormalities are often suggestive of posterior positional molding.