Key Differences Between Plagiocephaly and Brachycephaly

Plagiocephaly and brachycephaly are two of the most commonly diagnosed types of flat head syndrome. Causes can be similar, yet the head shapes look very different—and telling them apart helps you take the next steps toward appropriate care.

So what are plagiocephaly and brachycephaly? This article outlines the key differences so you can move toward the right treatment path.

Brachycephaly

It appears as a distinctly wide and high head shape.

If your baby has brachycephaly, around eight weeks you may notice flattening at the back of the skull that makes the head look much wider than usual. The back of the head may also look taller, and in some cases there may be bulging toward the front of the skull in the upper face region.

Brachycephaly usually appears in the first few months of life, when the skull is still soft, moldable, and sensitive to external pressure. Several causes are described in our informative article on brachycephaly and how it can be managed. Active steps are needed so the deformity does not worsen or become lasting.

Plagiocephaly

Plagiocephaly is the most common type of flat head syndrome and refers to an asymmetrical head shape with flattening on one side. Often compared to a parallelogram, it gives a skewed appearance with flattening on the left or right.

Classifying severity without a clinical evaluation can be difficult. The most common form is diagnosed as positional plagiocephaly. Besides flattening, other signs to watch for include:

• Ear misalignment. Ears and cheeks on the flatter side may be pushed forward.
• Facial asymmetry and differences in eye size or position (one eye may look lower or smaller). The brow area may also project outward.
• A combination of brachycephaly and plagiocephaly is also common and presents as a wide, asymmetrical head shape.

What Causes Plagiocephaly and Brachycephaly?

Despite key differences, many babies we see have a combination of both. That does not mean two separate diseases—the terms are clinical descriptions of how the head has flattened.

Despite their differences, both conditions are most often linked to one or more of the following:

• Soft skull – Babies are born with very soft skulls that help them pass through the birth canal and accommodate rapid brain growth in the first months. Skull bone plates do not fuse until around walking age, so they are highly sensitive to shape change—including from position in the womb.
• Multiple births – Flat head syndrome is common in multiples because there is less room to move in the uterus and added pressure on soft skull bones.
• Premature birth – Preterm infants are especially vulnerable because they miss late-pregnancy bone mineralization. They may also prefer to rest the head on one side before they can move it well, which can contribute to skull shape concerns.
• After birth – Pressure on the head after birth is one of the most common causes of plagiocephaly, especially when the head rests for long periods on flat surfaces. Conditions such as torticollis (tightness of a neck muscle on one side), which can be treated with physiotherapy, can make this worse.

What Treatment Is Available for Plagiocephaly or Brachycephaly?

Flat head syndrome is the general term, but not every flattening looks the same. Parents often feel confused and anxious when they do not have a clear explanation of their baby’s situation.

As soon as flattening becomes noticeable, we recommend starting frequent repositioning guidance. This can help prevent worsening of plagiocephaly and brachycephaly and may even help reverse milder changes. Natural improvement, when it occurs, is usually in the first weeks of life—typically up to about four months of age.

While sleeping – Place the baby on the back to sleep and encourage different head sides by changing which end of the crib you use. Move the night light to different sides of the room (babies tend to follow light with their eyes and head—make sure it is not always in one direction) and check and change head position during sleep when needed.

While playing – Use tummy time to strengthen important neck and trunk muscles. While awake, place the baby prone on a firm, flat surface. This also supports development and coordination. Leaving a baby on the back for too long can create similar pressure, so tummy time helps reduce that.

While feeding and carrying – Switch the side you hold the baby on to encourage equal movement of both sides of the head.

While traveling – When possible, limit time in car seats and strollers where the head rests on a hard, flat surface for long periods. Prefer a sling or soft carrier instead of prolonged car-seat carrying.

Next Steps for Plagiocephaly and Brachycephaly

Our aim in these difficult moments is to provide reassurance and clear guidance. We can assess your baby’s needs clearly and honestly, because you cannot know where you are going without knowing where you started. We always measure each head shape so we know where to allow growth and correction.

In our experience, if plagiocephaly and brachycephaly have not improved on their own by about five months of age, they are unlikely to resolve without further help. In those cases, CranioWell cranial helmet therapy—fitted only at CranioWell Orthotics & Prosthetics Centers—can be used to gradually guide the head toward a more typical, symmetric shape.

For benefits of the helmet in plagiocephaly and brachycephaly and answers to common questions, read our FAQ. See our blog for more resources on plagiocephaly and brachycephaly, including links to additional advice and support.