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Plagiocephaly is the technical term for a flat spot on a baby’s head. It might seem alarming at first glance, but it is not at all uncommon and in most cases it’s completely benign.

Babies head

Causes of Plagiocephaly

Very young babies’ skulls are very mobile- this is important during birth. The mobility is due to the joints between the bones of the skull being soft. In an adult skull, they are still present but they are not mobile like a knee or hip. In addition to the character of the joints, the bones themselves are quite soft too. The “soft spot” on the top of the head makes this particularly clear, visibly changing shape depending on hydration and pressure (more domed when baby cries or screams). So it’s not too surprising that prolonged pressure on one part of the head could cause a flat spot.

Before a baby develops neck strength, they will spend a lot of time laying down or reclining. Especially if there is an underlying problem that causes them to favour one side, such as torticollis, one area may take the pressure more than the rest.

Plagiocephaly vs Brachycephaly

To be more precise, plagiocephaly refers to a flat spot that is on the posterio-lateral head. From the top down, this is the diagonal between the back and side. It may cause a similar asymmetry in the front of the head as compensation. Brachycephaly is a flat spot at the very back of the head. This might lead to prominence in the forehead.

Red Flags

Not all flat spots are benign, unfortunately. Rarely, one or a few of the joints in the skull can fuse early. A baby’s brain grows incredibly quickly. By three months old, the brain is half the size it will be as an adult. Growth slows after three months, but still requires the skull to accommodate relatively rapid growth until toddlerhood.

Craniosynostosis is the name of the condition when fusion happens too early. Rather than a single flat spot, this might cause the head to be more wedge shaped or otherwise unusual. If we suspect that this is the cause of your baby’s symptoms, we will refer you back to your GP for further investigation.

Managing Plagiocephaly

The NHS does not routinely recommend the use of helmets due to their cost, potential discomfort, and lack of evidence of efficacy.

Your osteopath will want to understand any underlying causes that have led to your baby’s flat spot. We will assess their neck movement and muscle tone to spot the factors mentioned above. Sometimes improving neck mobility is enough to prevent the consistent pressure to one part of the head. At this point, the problem can solve itself.

For other babies, it might be more effective to work on gross motor ability. Encouraging the adoption of positions like laying on their front, or beginning to sit, mean that less time is spent with any pressure on the head at all. Initially, they may resist spending time on their tummy, and we can assess whether that is because of another issue or something that will improve with practice.


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