Overview

Plagiocephaly [ pley-jee-uh-sef-uh-lee ], or “flat head syndrome”, is a common problem in babies. Babies often sleep on their backs, which can cause a flat spot on one side of their head to develop, resulting in asymmetry. This is called positional, or deformational plagiocephaly, and affects up to 22.1% of infants at the age of 7 weeks.

The prevalence of plagiocephaly declines with age, decreasing to 3.3% by the age of 2.¹ Sleeping on their back is the safest sleeping position and has been encouraged by medical authorities since 1992, when the “Back to Sleep'' campaign began advocating for it, pursuing to reduce the risk of sudden infant death syndrome (SIDS). Fortunately, the rates of SIDS decreased significantly, but plagiocephaly became a more frequent problem.^1,2,3 

In this article, we will detail plagiocephaly in infants, its causes, risk factors, symptoms, diagnosis, and treatment. 

What is plagiocephaly? 

Plagiocephaly is an asymmetry of the human head, caused by flattening on one side. The term means “oblique head”, originating from the Greek words, “plagios” and “kephalē”. There are two main types of plagiocephaly based on the causing factors: deformational or synostotic.^2,4

Deformational plagiocephaly is the most frequent type, commonly seen in babies a few months after being born. Also called positional plagiocephaly, it is caused by mechanical forces acting on the baby’s head, inside the womb, during birth, or early after being born. These forces deform the shape of the baby’s head.¹

The bones protecting our brain and giving it the shape of our head, form the human skull. A newborn’s skull is softer and the bone plates are not yet fused. Fusion of the bone plates normally happens after the brain has completely grown and developed. This fusion is called “synostosis” and is the cause of the second type of plagiocephaly, called synostotic plagiocephaly, or craniosynostosis. Synostotic plagiocephaly is a rare type of plagiocephaly, affecting one in 2,200 babies.^1,2,5

What causes plagiocephaly?

In most cases, plagiocephaly is caused by mechanical forces acting on the baby’s head during birth. Because the baby has to pass through the birth canal, their skull can slightly change its shape to fit. This change naturally improves over time, and the baby’s head returns to normal, but this doesn’t happen if the baby only sleeps on their back.⁶ 

Some factors act inside the womb. The foetus can have an abnormal position, the uterus can have an irregular shape, or, in the case of multiple pregnancies, the limited space inside the womb can cause mechanical forces to be applied against the foetal head, leading to positional plagiocephaly.^2,6 

Intrauterine or postnatal abnormal head position, difficult delivery, birth trauma, or a congenital muscular condition, can cause neck problems in babies. Up to 90% of the babies suffering from congenital muscular torticollis, develop plagiocephaly. The sternocleidomastoid muscle, a neck muscle, can be injured during birth and shortened on one side. The baby will prefer to hold their head on that side, leading to positional plagiocephaly.^1,6,7

When plagiocephaly is linked to craniosynostosis, the possible causes are:²

• Genetic mutations
• Bone abnormalities
• Maternal exposure to certain medications (valproic acid)
• Hyperthyroidism (overactive thyroid)
• Preterm delivery (prematurity)
• Low birth weight

What are the risk factors for plagiocephaly?

The following factors may increase your baby’s likelihood of developing plagiocephaly:

• Assisted delivery
• Baby is a firstborn child
• Baby has neck problems
• Baby sleeping repeatedly in the same position
• Lack of tummy time

People assigned male at birth (AMAB) have a higher risk of developing plagiocephaly. This is due to their increased head dimension, less body flexibility, and accelerated growing rate, especially in the first 3 months.^1,2 

What are the symptoms of plagiocephaly? 

Typically, plagiocephaly is visible a few months after birth. Less frequently, symptoms can be seen at birth if the mechanical factors changing the shape of the skull are acting before or during birth. Because the head usually reverts to normal shortly after birth, positional plagiocephaly is considered a diagnosis after the baby is 6 weeks of age.¹

Plagiocephaly is an asymmetry of the skull. The shape of the head is described as a parallelogram, with the back of the head, called “the occiput”, flattened on one side. The ear on the flattened side is shifted and misaligned with the other.

Sometimes the face and the forehead are also affected on the flattened side; the lower jaw and the eye pit change, causing facial asymmetry. In rare cases, the flattening can be on both sides of the occiput – this is called “brachycephaly”. Both plagiocephaly and brachycephaly, are considered types of “flat head syndrome”.^3,6,8 

How can plagiocephaly be diagnosed? 

If you notice that your baby’s head shape is not oval and symmetric, a paediatrician can examine your baby and determine the diagnosis. During the physical examination, the doctor will measure your baby’s head diameters to determine the severity of the plagiocephaly.² 

The clinical assessment may also include a neck examination, where the range of motion of your baby’s neck will be observed. The paediatrician will identify if your baby has a side preference due to congenital torticollis (tight neck). In this case, your baby may be referred to a physical therapist, who can help recommend stretching exercises to improve the neck problems and head deformation. Cervical spine abnormality can also cause plagiocephaly, so doctors may examine your baby’s cervical spine.⁸

What are the other diagnoses to think about?

Craniosynostosis is the principal condition doctors consider when examining a baby with plagiocephaly. The premature fusion of the skull’s bone plates impacts the growth and development of the brain, so early detection and treatment are vital. The paediatrician can ask for a computer tomographic scan with three-dimensional reconstruction (3D CT scan) of your baby’s head, the most accurate test to assess the fusion of the bone plates.

If craniosynostosis is identified, your baby will be further consulted by other specialists: a neurosurgeon, a plastic surgeon, or clinics specialising in baby head shapes. In less frequent cases, craniosynostosis can be caused by a genetic condition. In these instances, your baby will also be evaluated by a geneticist, and further tests, such as:

• Genetic tests
• Ultrasound examination
• Magnetic resonance imaging (MRI)

These tests are necessary to exclude possible brain anomalies, complications, or genetic syndromes.^2,5,6 

What is the treatment for plagiocephaly?

Plagiocephaly can be naturally corrected by the age of 2. However, it depends on the severity of the deformation, and a full result is rare. Every case needs careful assessment and appropriate intervention. The treatment can be conservative or surgical. Positional plagiocephaly is commonly treated conservatively with:^2,6,8

• Positional therapy
• Physiotherapy
• Helmet therapy

Positional therapy (posture changing) is recommended for babies up to 4 months of age and corrects mild to moderate plagiocephaly by frequently changing your baby’s sleeping position. In the case of congenital torticollis, physiotherapy is recommended as soon as possible, before 4 months of age, as this would improve neck and trunk strength, favouring the correction of the head shape.^2,4,6

Helmet therapy also known as “cranial remoulding helmet”, is the next step if positional therapy isn’t working for mild to moderate cases, and your baby is already 6 months. In severe cases, this therapy is recommended sooner. The helmet is customised to correct your baby’s head asymmetry. It is effective when started in the first year of life, especially, if combined with posture changing and physiotherapy. After 18 months, the results are very poor.^6,8

In severe cases, surgery may be needed when the head asymmetry causes complications regarding facial appearance, vision, chewing, or eating. If your baby has craniosynostosis, surgery is a must to allow the growth and development of the brain. Surgery is most effective when the baby is between 6 and 12 months. Helmet therapy after surgery is beneficial to prevent recurrence and allow the head and brain to develop normally.^2,5,6,8

Awareness, education, and prevention

There are some controversies regarding whether helmet therapy improves the outcome in severe cases. The helmet must be worn for 20-23 hours daily, for 6 to 12 months, depending on each case. This therapy has some drawbacks including, the costs and the practical inconvenience because the baby has to wear it all day. Further complications concerning insufficient correction and skin reactions include:^2,6,8

• Contact dermatitis
• Pressure damage
• Scalp sores
• Temporary hair loss 

Positional plagiocephaly can be prevented if you alternate your baby’s sleeping position so that they lie on both sides of the occiput equally. “Tummy time”, at least 3 times a day, for 10 to 15 minutes, is crucial because it helps your baby progress in their developmental milestones.^2,6,8 

Craniosynostosis is a rare, complex congenital condition, sometimes related to genetic syndromes, so it can’t be prevented. A team of specialists and surgery is necessary to avoid the possible complications of untreated craniosynostosis:^2,5

• Developmental delay
• Learning difficulties
• Sight
• Hearing
• Eating problems
• Facial deformations

Summary

Plagiocephaly is a frequent problem in babies, defined as an asymmetry of a baby’s skull due to the development of a flat spot. Positional plagiocephaly is the most common type, caused by external factors acting on the baby’s head during pregnancy, birth, or early after being born. Neck problems, such as congenital muscular torticollis, are a common cause of positional plagiocephaly. Plagiocephaly linked to craniosynostosis is rare, severe, and caused by variable possible factors, such as genetic syndromes, maternal conditions, medication during pregnancy, and others. This type can’t be prevented and requires immediate diagnosis and surgery. Positional plagiocephaly can be prevented, by alternating the baby’s sleeping position and spending enough “tummy time”. 

Treatment can be conservative or surgical. Conservative therapies include posture changing, physiotherapy, and cranial remoulding helmets. Parent education, increased awareness, early detection, and adequate intervention are key factors in reducing the rate of new plagiocephaly cases. This will improve the overall health outcomes of the affected babies and reduce the costs involved in the treatment, support therapies, and complications management.