What is positional plagiocephaly?

Positional plagiocephaly is a deformation of the bones of the skull that produces a characteristic asymmetry of the head.

The Hospital for Sick Children (SickKids), Toronto

Why is it called positional plagiocephaly?

There are many terms used to describe this condition including deformational plagiocephaly, positional plagiocephaly or plagiocephaly without synostosis. All of these refer to the same thing. The term plagiocephaly is derived from the Greek plagios meaning oblique and kephale meaning head.

The term synostosis means fusion across the sutures joining the different bones of the skull which can also produce asymmetry involving the shape of the head. Positional plagiocephaly describes a condition where the head shape is asymmetrical because of deformation, not because of fusion of the sutures. Hence, the name, plagiocephaly without synostosis, PWS.

Why does this occur?

Positional plagiocephaly is the result of the baby’s head staying in the same position for a prolonged period of time. The skull bones in a newborn infant are quite thin and flexible allowing for passage through the birth canal. Quite often, a child may show asymmetry at birth due to positioning in the uterus or birth canal. This same flexibility may result in molding of the head as the result of prolonged lying in the same position.

As the result of the “Back to Sleep” campaign by the American Academy of Pediatrics to reduce the incidence of Sudden Infant Death Syndrome (SIDS), children are being placed on their backs when they sleep. If the child is not repositioned every 3 to 4 hours, or if they indicate a preference to stay in the same position, molding of the skull from constant pressure and effects of gravity can occur in a gradual fashion that produces asymmetry of the head.

Are there any other conditions that cause this?

The most common cause of positional plagiocephaly is due to positioning of the head in one position. These asymmetries can be caused by a number of factors, some of which are interrelated, such as positioning in utero, prematurity, difficult delivery or positioning after birth.

Occasionally, tightness of one of the neck muscles can result in positional plagiocephaly if the child cannot look easily to the opposite side. This condition is known as torticollis and your child will be checked for this when he or she is seen in the clinic.

There are some other very rare causes that cause the head to be tilted to one side, which will also be ruled out as the result of the clinic visit. Finally, skull asymmetry is very rarely caused by a premature fusion of the sutures between the different skull bones. This condition produces typical skull shapes and is easily picked out from skull asymmetry due to positional plagiocephaly.

What does positional plagiocephaly look like?

You may notice that your child has one or more of the following

• Flattening of one side of the back of the head
• Flattening of the opposite forehea
• Uneven positioning of the ears
• One eye may appear lower and/or smaller than the other
• An increased head height toward the back of the head

Can positional plagiocephaly affect the brain?

It is important to realize that positional plagiocephaly is not a disease but a simple deformation of the skull. As a result, there is no effect on the development of the brain. As we like to say, the brain does not care what shape it is, as long as it has the space to grow.

Does my child need x-rays?

Typically, most children do not need x-rays to diagnose positional plagiocephaly. In occasional cases, an x-ray of the skull or a CT scan may be used to help differentiate different types of skull asymmetry from positional plagiocephaly.

Will my child’s head shape improve with time?

The answer is yes. Between 4 to 6 months of age, your child will develop improved head control, which results in better movement and a lesser tendency to remain in a fixed position.

Studies have shown that head shape spontaneously improves after the first 6 months. If your child has PWS in association with torticollis, it is important to realize that as the torticollis improves, and neck movement gets better, so will your child’s head shape.

Why does my child need treatment?

Treatment for positional plagiocephaly is primarily cosmetic, to address potential self image issues that develop later in life. During the clinic visit, your child will be checked for possible underlying causes of positional plagiocephaly. It is important to treat these conditions if the head shape is to improve. If the head shape is very asymmetrical, your child may benefit from further intervention in the form of a molding helmet.

A molding helmet is just what it sounds. It is a helmet similar to that worn in sports or bicycling that allows for controlled molding of the skull. The orthotist will carefully measure the shape of your child’s head and construct a plastic helmet. This helmet is custom fitted to the shape of the head and is designed to do two things.

Firstly, it will act as a protective cushion to prevent undue pressure on one side of the head and allow for better distribution of the pressure along the bones of the skull. Secondly, the helmet is fitted in such a way as to allow for the bones of the skull to expand in the flat areas in response to the underlying growth of the brain.

Learn more about molding helmets at SickKids.

Will my child need surgery?

No, the large majority of patients with PWS do not need surgery. Rarely, if there is a residual asymmetry that is noticeable, surgery may be performed but is usually delayed until the child is 7 to 9 years of age.

Source The Hospital for Sick Children (SickKids)
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A Clincian’s Guide to Positional Plagiocephaly, Meghan Steward & Patricia Mortenson, with assistance from Laurie Hasiuk, Learning & Development, BC Children’s Hospital. BCCH034 © June 2008. Adapted from A Clinician’s Guide to Positional Plagiocephaly, © 2003 The Hospital for Sick Children, Toronto, Ontario.

Also see
Positional plagiocephaly Canadian Paediatric Society
What is deformational plagiocephaly? The Children’s Hospital of Philadelphia