May 2026
craniosynostosis-causes-symptoms-treatment
Craniostenosis is a condition in which one or more of a baby's cranial sutures are closed. This affects how the head continues to grow and develop. Medical institutions such as the Mayo Clinic explain that this is a structural condition, which is not caused by the way a baby lies or sleeps. This does not automatically mean that a flat or uneven head shape is craniosynostosis. Most changes in head shape in babies are positional and improve when babies turn their heads into different positions. Craniosynostosis is less common- it is even rare - and follows specific growth patterns. Early recognition helps determine the correct diagnosis. Understanding the difference helps reduce unnecessary worries.
Craniosynostosis is a premature fusion of a suture that restricts growth and deforms the head. It is not caused by external pressure such as a positional preference.
How a baby’s skull normally grows
A baby's skull is made up of several bones connected by flexible sutures. These sutures allow the skull to expand as the brain grows rapidly in the first year. The soft spots, or fontanelles, also provide space for this growth. Normally, the sutures are open during early development. This allows the skull to grow evenly in all directions. Over time, the sutures gradually close in a natural sequence. This process supports balanced head shape and brain development. Flexibility is essential during this stage — to understand what this looks like on the outside, read our article on the soft spot on the head of a newborn.
What happens in craniosynostosis
Did you know that in craniosynostosis, the specific suture or sutures did not open during development in the womb? So it wasn't closed 'too early' as stated in much of the information, but the suture was actually never open. It is therefore present from birth. The skull cannot grow around the closed suture. Consequently, the head grows more in other directions to compensate for this. This leads to characteristic head shapes, depending on the affected cranial suture. Unlike positional flattening, this is not caused by pressure or posture. An important indicator is that the shape already looks different at birth, is deformed, and that the deformity becomes increasingly visible. This difference is important for the assessment.
Causes of craniosynostosis
The exact cause of craniosynostosis is often not clearly known. In many cases, it occurs without a specific reason. Some cases are linked to genetic factors or developmental differences during pregnancy. It is not caused by sleep position or caregiving practices. External pressure does not lead to suture fusion. This distinction is important for parents who may feel responsible. Most cases are isolated and not part of a broader condition. Understanding this helps reduce unnecessary guilt.
Symptoms and early signs
Parents may notice an unusual head shape at or shortly after birth, and that the shape becomes increasingly noticeable over time. The head may appear long, narrow, broad, asymmetrical, or flattened. A palpable ridge running from front to back on top of the head can be a signal. However, the size of the fontanel is precisely not a clear signal for craniosynostosis. Unlike positional flattening, the shape does not improve by repositioning the head. These signs may cause concern, but many variations in head shape are still normal. It is important to seek advice from a pediatrician or pediatric physiotherapist if in doubt.
Craniosynostosis vs flat head syndrome
The clear difference from flattening caused by external pressure is:
Craniosynostosis is present and visible from birth;
It does not improve by repositioning or moving the head.
The cause of craniostenosis is fused cranial sutures and not the baby's lying position. These differences are the main ways to distinguish the two. Most babies with an asymmetrical head shape have positional flattening. Craniostenosis is rare. A physician specializing in craniosynostosis can often detect closed cranial sutures visually. Understanding this prevents unnecessary anxiety.
How doctors evaluate craniosynostosis
Most evaluations begin with simple clinical assessment. Doctors begin with observation of head shape and growth patterns. This clinical observation is usually sufficient to make the diagnosis. Therefore, a CT scan will only be performed if the doctor seriously suspects craniosynostosis. They want to prevent unnecessary exposure of the baby to X-rays. Measurements such as cephalic index (CI) and cranial vault asymmetry index (CVAI) are used for positional conditions. In craniosynostosis, clinicians focus on restricted growth and fixed patterns. The goal is to distinguish structural causes from positional ones. Early evaluation helps guide next steps.
Treatment options and when surgery is considered
Treatment depends on the type and severity of craniosynostosis. In confirmed cases, surgery may be considered to allow normal skull growth. This is sometimes referred to as craniosynostosis surgery or craniosynostosis operation. The goal is to create space for the brain and improve head shape. Surgery is usually planned within the first year of life, sometimes within months, when the skull is still flexible. Not all cases require the same approach. Decisions are made based on clinical evaluation. Specialists guide families through the process carefully.
What craniosynostosis surgery involves
Craniosynostosis surgery involves reshaping parts of the skull to allow normal growth. There are different techniques, including minimally invasive and open procedures. Minimally invasive surgery is often done earlier and may involve shorter recovery. Open surgery is used in more complex cases. Both approaches aim to correct growth patterns and support development. Most babies recover well with appropriate care. Follow-up ensures proper healing and growth. Outcomes are generally positive when treated early.
What this does not automatically mean
An unusual head shape does not automatically mean craniosynostosis or the need for surgery. Most babies with head shape differences have positional flattening, which improves over time. Back sleeping, while important for safety, can contribute to temporary flattening. This is expected and manageable. Surgery is only considered in confirmed structural cases. Avoid assuming the worst based on early appearance. Observing change over time provides important information. When in doubt, evaluation can provide clarity. FAQs
Is craniosynostosis common?
It is less common, it is even rare, than positional flat head syndrome.
Does craniosynostosis always require surgery?
No, treatment depends on the type and severity.
Can flat head turn into craniosynostosis?
No, positional flattening does not cause suture fusion.
Is craniosynostosis serious?
It requires evaluation, but outcomes are generally good with appropriate care.
Writen by Elly van der Grift
Elly van der Grift is a pediatric physiotherapist with more than 30 years of experience helping families understand infant head growth and development.