Introduction to positional plagiocephaly

What is positional plagiocephaly?
Positional plagiocephaly, or flat head syndrome, is the term for an abnormal shaped head caused by external pressures. Most often this is seen as a flattening at one side of the back of a baby’s head, giving an asymmetrical shape when seen from above, or it is where the width and length of the head are noticeably out of proportion – either abnormally wide, or abnormally long.

While many babies are born with an abnormal head shape, which comes as a result of the birth, most newborn heads will revert to a normal shape by the time the baby is six weeks old. If an abnormal shape persists or is not noticed until after six weeks, it may be that the baby has positional plagiocephaly.


How is it caused?
There are a number of causes:

• in utero constraint – this is where the womb is constricted somehow during pregnancy. This can happen when there is more than one baby, when the mother has a small uterus or pelvis, when there is too much or too little amniotic fluid, and when a breech baby’s head is wedged underneath the mother’s ribs
• prematurity – the skulls of premature babies can be very soft and malleable, making the head more susceptible to moulding due to external pressures
• torticollis – this is a condition in which a tight or shortened muscle on one side of the neck causes the head to tilt and/or turn to one side. It is usually present from birth (congenital muscular torticollis) and may be obvious or subtle. Torticollis can be caused by up to 80 different pathologies. Most are benign and muscular torticollis is one of these. Others are potentially life threatening if the bones in the neck are damaged or not forming properly. It is important to have suspected torticollis diagnosed properly and to have it treated by a specialist physiotherapist.
• back sleeping and continual pressure on the back of the head - since the advent of the “Back to sleep” campaign (which began in November 1991), where parents are advised to place their babies to sleep on their backs to reduce the risk of sudden infant death syndrome (SIDS/cot death), there has been a rise in positional plagiocephaly. Because of the fear that many parents have of cot death, babies these days spend an extended amount of time on their backs – in car seats, Moses baskets, pushchairs, bouncy seats and the like. Babies’ skulls are soft in the first few months of life, and continual pressure on one area of the head like this can cause it to flatten. Torticollis and/or prematurity can worsen the flattening.

What are the characteristics of positional plagiocephaly?
Positional plagiocephaly is the umbrella term for three types of positional head deformity – plagiocephaly, brachycephaly and dolichocephaly:

	With plagiocephaly, the side that is flattened will often be accompanied by a prominent forehead, which when viewed from above will give the head a parallelogram shape instead of a normal symmetric oval shape. It is also common for the baby to have misaligned ears - the ear on the affected side may be pulled forward and down and be larger than the unaffected ear. There is also sometimes asymmetry of the face, with the affected side having a fuller cheek and a more prominent appearance. Facial asymmetry can also include a jawbone that is tilted, and an eye that appears displaced and mismatched in size. Facial asymmetry is when one side of the face does not match up with the other side. Essentially, the face appears lopsided, or simply does not look right.
	Brachycephaly is diagnosed when the entire back of the head is flat and the head has the appearance of being wide and short (from front to back). There is sometimes bossing of the forehead. Brachycephaly is most often seen when a child sleeps entirely on the back of his head.
	Dolichocephaly is characterised by a long and narrow head shape. It can result from extended time spent lying on the side of the head, such as premature babies in neo-natal units do. It can also be caused when the baby is in a breech position during the pregnancy and the head becomes wedged underneath the mother’s ribs (really called bathrocephaly, but this term is little-known). In the US, these conditions are both referred to as scaphocephaly, but technically, this is where the baby has the same shaped head, but where it has been caused by craniosynostosis, where the saggital suture has fused prematurely.

Craniosynostosis
Technically, the word positional or deformational is used so that the condition is differentiated from craniosynostosis, which is a premature fusion of one or more of the skull sutures (the gaps between the skull plates) and which requires surgery. It is important that craniosynostosis is ruled out before repositioning or helmet therapy is considered. Paediatricians and helmet providers are skilled at doing this. As a general rule, in positional plagiocephaly, on the flattened side the ear is pushed forwards, but with craniosynostosis, the ear on the flattened side is pushed more towards the back of the head than the other one.

However, if there is any uncertainty, a referral to one of the four designated UK craniofacial units should be sought. The units are at Alder Hey Children's Hospital in Liverpool, Birmingham Children's Hospital, The Radcliffe Infirmary at Oxford and Great Ormond Street Hospital in London. These units are funded by the NHS's National Specialist Commissioning Advisory Group (NSCAG) and are called centres of excellence. It does not matter if you do not live in the Primary Care Trust area of any of these hospitals, as you can choose to seek assessment for your child at any of them at no cost to your GP. The assessment and any treatment necessary is funded by NSCAG. Some people do choose to pay privately for advice, assessment and if necessary treatment for craniosynostosis thinking that they will get quicker treatment - but this is not true as GP's referrals to any one of these units results in an appointment within a month, if not sooner. Assessment most typically takes the form of an X-Ray, CT or MRI scan to check for craniosynostosis.


What can be done about positional plagiocephaly?
Great Ormond Street Hospital points out that “some reports estimate that positional plagiocephaly affects around half of all babies under a year old but to varying degrees.” While mild cases of positional plagiocephaly can improve on their own once a baby starts to gain mobility and spends less time resting its head on hard surfaces, research estimates that 1 in 15 cases of plagiocephaly will not have resolved by the time a baby is one.

Early recognition of plagiocephaly is important. The younger the child is when it is recognised, the better the chances of stopping any progression. Giving young babies plenty of supervised “tummy time” during the day, and ensuring their heads are not always resting on the same area will give them the best opportunity to grow up with a normal-shaped head. Babies should still be placed to sleep on their backs though, in line with the recommendations from the Foundation for the Study of Infant Death, as the benefit of reducing SIDS far outweighs any dangers due to positional plagiocephaly.

If positional plagiocephaly still develops, or worsens, older babies – over about five or six months old – can be fitted with a custom-made helmet that naturally allows their heads to come back to a normal shape as they grow.


If a baby has torticollis, then a referral to a paediatric physiotherapist should be sought. Only once the head regains full mobility can natural correction of head shape can begin. Torticollis needs to be ruled out or resolved for repositioning or helmet treatment to be fully effective.

For more information on treatment options, see the treatment page.


Diagnosis of severity
Diagnosis of severity of plagiocephaly is determined by taking measurements of the baby’s head by hand (or with an optical scan). The private helmet providers all offer free initial consultations that will give a diagnosis of severity, but NHS hospitals and paediatricians do not seem to take these measurements.

Asymmetry
With plagiocephaly, severity is determined on the degree of asymmetry, in millimetres, of the baby’s head. The two diagonals of the head are measured with calipers, from above the corner of each eye, across the centre of the head to the back. The smaller length is subtracted from the larger to give the asymmetry.
The classifications in the UK are generally:

• Mild plagiocephaly - less than 6mm
• Moderate plagiocephaly - 6 to 12mm
• Severe plagiocephaly - over 12mm, but measurements of over 20mm are not uncommon

Cephalic ratio / cranial index
With brachycephaly and dolichocephaly, asymmetry is not a factor unless there is a combination of brachycephaly with plagiocephaly. Instead, the cephalic ratio (or cranial index) is the measurement that determines the severity. Cephalic ratio is the head width as a percentage of head length, again measured using calipers.

An “ideal” head has a cephalic ratio of 78% and the "normal" range is 73-83%.

• Moderate brachycephaly – 83.1% to 87.9%
• Severe brachycephaly – 88% and over, but measurements of over 100% are not uncommon
  
• Moderate dolichocephaly – 68.1% to 72.9%
• Severe dolichocephaly – 68% and less