Plagiocephaly Dr Trisha Macnair Babies often have a flattened area of the head from sleeping on their backs, but sometimes there are more complications.

In this article

What is plagiocephaly? Symptoms

Causes and risk factors Treatment and recovery

The skull isn't perfectly smooth - it's covered with lumps, dips and some flatter areas. But sometimes a large area of flattening distorts the skull, making it look parallelogram-shaped. This is known as plagiocephaly.

Plagiocephaly may become apparent at different ages, depending on the cause. Some babies are born with a flat head (this may be a temporary deformity due to the baby's passage down the birth canal), while others develop it later as the bones of the skull fuse. The abnormal shape can best be seen if you look down on the baby's head from above.

Signs of plagiocephaly include:

• Parallelogram-shaped skull when viewed from above
• Flattening on one side at the back of the head, with a compensatory protrusion or bulge in the forehead on the same side
• Eyes appearing to have unequal positioning
• A bald spot on flattened side (may be asymmetrical)

It's important the type and cause of plagiocephaly are determined, as each requires different treatment. X-rays, CT scans and other tests may be needed to confirm diagnosis.

A baby's skull is very soft and can be forced to grow in different directions fairly easily. When the skull is kept in one particular position for long periods - because the baby is sleeping in a set position (such as on his back) or because muscles attached to the skull go into spasm (known as torticollis) - areas of the skull may be squashed or pulled flat. This is known as positional or deformation plagiocephaly. It generally gets better by itself over time.

Other factors that increase the risk of plagiocephaly include a multiple birth pregnancy (as the babies 'squash together' in the womb), prematurity, poor muscle tone and a condition known as oligohydramnios, where there's insufficient fluid in the womb to cushion the baby.

In the US at least, plagiocephaly has become more common in recent years. Statistics show that while one in 300 healthy infants was affected in 1992, by 1999 one in 60 had the condition.

This increase is thought to be due to the Back to Sleep campaign, designed to reduce the number of sudden infant deaths (cot deaths).

It's possible to prevent positional plagiocephaly by changing your baby's resting position frequently. Your baby still needs to be laid on their back to sleep, but try to alternate the position of the head and encourage them to spend time on their tummy while they're awake and supervised.

Switch between putting them in a sloping chair, car seat or sling, or on a flat surface, so there's no constant pressure on one area of the skull.

Plagiocephaly may also be caused by the bones of the skull joining together abnormally early. These bones normally grow together slowly so the skull expands in all directions. But if some fuse too soon (craniosynostosis), that part of the skull can't grow in the way it should, pulling the head out of shape. This may occur in isolation, or as part of a genetic syndrome such as Apert syndrome or Crouzon syndrome.

Initially at least, the same technique is used to treat most cases of positional plagiocephaly as to prevent it. By keeping your baby off the part of the head that has flattened, growth should even out.

It will take some time to see improvements - usually six to eight weeks. If your child has torticollis (spasm of the neck muscles), treatment may include physiotherapy and neck exercises to increase movement of the head and neck.

If plagiocephaly has resulted from premature fusion of the skull bones, an operation is almost always required to unlock and move the bones. Long-term complications include asymmetry of the face (in about ten per cent of cases) and persistent flattening (in as many as one in three cases). It can also be linked to developmental delay.

This article was last medically reviewed by Dr Orlena Kerek in March 2009