What Is Lambdoid Craniosynostosis?

One of the rarest types of craniosynostosis, a birth defect

Lambdoid craniosynostosis occurs when the lambdoid suture, a joint in your infant’s skull, fuses prematurely. The lambdoid suture runs along the backside of the head. When it fuses, the back of the head appears flattened. It is one of the rarest types of craniosynostosis, a birth defect affecting the joints in a baby’s skull.

Sutures normally remain open and flexible until your child’s second birthday. This allows the brain room to grow and develop. In craniosynostosis, one or more of the sutures fuse prematurely. This causes the skull and head to grow into a misshapen form. It may also lead to increased pressure on the brain.

Treatment for lambdoid craniosynostosis involves surgery to correct the shape of the head and allow room for the brain to grow. 

Doctor using stethoscope to check newborn baby health and take care of them or cure the disease or disorder

Narongrit Sritana / Getty Images

Types of Craniosynostosis

There different types of craniosynostosis besides lambdoid craniosynostosis, including:

  • Sagittal craniosynostosis is the most common type of craniosynostosis. It affects the sagittal suture that runs from the front to back of the head. It results in a long, narrow head.
  • Coronal craniosynostosis affects one or both of the coronal sutures, which run from the ear to the top of the head. This type of craniosynostosis causes the forehead to appear flattened and bulging on the affected side.
  • Metopic craniosynostosis affects the metopic suture, which runs from the top of the bridge of the nose up to the top of the head. This type of craniosynostosis causes the forehead to look triangular and widens the back of the head.

Lambdoid Craniosynostosis Symptoms

The most noticeable sign of lambdoid craniosynostosis is a flattening of the backside of the head. You may also observe that your baby’s ear and forehead on the affected side look like they’re pulling backward. This gives the head a trapezoid-shaped appearance. The ear on the affected side may also look lower than the ear on the unaffected side.

Other common symptoms of lambdoid craniosynostosis include:

  • A hard ridge along the lambdoid suture on the backside of the head
  • Slowed head growth while the body continues to grow

Rare symptoms may include:

  • Sleepiness or fatigue
  • Irritability and crying
  • More prominent scalp veins
  • Poor feeding
  • Projectile vomiting
  • Increased head size (circumference)
  • Developmental delay

Is It Definitely Craniosynostosis If Your Baby’s Head Looks Misshapen?

If you notice that the backside of your baby’s head appears to be misshapen, it may not be lambdoid craniosynostosis. Babies who spend most of the day on their backs may develop a flattened back of the head because their flexible skull bones can easily be molded. This condition is known as positional plagiocephaly. This benign condition does not affect brain growth and does not require surgical treatment.


Lambdoid craniosynostosis is often considered a random birth defect and does not have a known cause. It may be caused by a combination of genetic and environmental factors. 

While we still do not understand the exact causes of lambdoid craniosynostosis, there are some risk factors that appear to raise a baby’s risk of experiencing this birth defect. 

The following risk factors are associated with craniosynostosis:

  • Multiple babies in a pregnancy, such as twins or triplets
  • Large head size in utero
  • Maternal thyroid disease
  • Maternal smoking
  • Use of fertility treatments such as Clomid (clomiphene citrate)


Lambdoid craniosynostosis is often diagnosed by physical exam. Your doctor may also order imaging studies to confirm the diagnosis. This is especially important with this type of craniosynostosis because it can appear similar to positional plagiocephaly, a benign condition. 

Your doctor will carefully examine your child’s head and feel the back of their head for a hard ridge along the lambdoid suture. Your doctor will also take time to distinguish your child’s symptoms from positional plagiocephaly. For example, lambdoid craniosynostosis causes the ears to look pulled back, while positional plagiocephaly makes them appear pushed up toward the face. 

Your doctor will also take a detailed history to learn about your family health history and ask specifically about any family members with a history of craniosynostosis, skull abnormality, or genetic disorder. 

Your doctor may then recommend a CT scan of your child’s head. A CT scan with three-dimensional (3D) reconstruction is considered the most accurate way to diagnose lambdoid craniosynostosis. This test can show your child’s lambdoid suture and any abnormalities in the brain.

Rarely, craniosynostosis presents as part of a genetic disorder. If your doctor suspects that’s the case, they will order additional tests and may recommend genetic testing for the family. 


Lambdoid craniosynostosis needs to be treated with surgery. The goal of surgery is to correct the shape of the head to allow the brain to grow normally. There are two types of surgery available to treat lambdoid craniosynostosis. Your doctor will discuss both options with you to determine the best one for your child.

Endoscopic Craniosynostosis Surgery

Endoscopic craniosynostosis surgery is a minimally invasive procedure that is available for babies before they turn 6 months old. During this procedure, your surgeon makes several tiny incisions in your child’s scalp and then uses a small tube called an endoscope to move the skull bones into a more circular shape.

This type of surgery needs to be performed between ages 2 to 6 months old because the skull bones are still soft and flexible enough to be shaped with an endoscope.

After the surgery, your child will need to wear a molding helmet until their first birthday to allow the head to continue to grow in a normal shape. They will have to wear it for 24 hours, including while they are sleeping.

Calvarial Vault Remodeling

Calvarial vault remodeling is a more invasive surgery that is performed once your child has turned 6 months old. During this procedure, the surgeon makes an incision in your child’s scalp and moves the skull bones into a circular shape. This surgery can take up to six hours to perform and may require a blood transfusion due to blood loss.

Calvarial vault remodeling is used in older infants because their skull bones are thick enough to be moved and hold their new shape. Babies who undergo this type of surgery do not have to wear a molding helmet afterward. 


Lambdoid craniosynostosis may be diagnosed at birth or during your child’s first year of life. Treatment will depend on your child’s age at diagnosis and how severe the skull malformation is.

The timeline for diagnosis and treatment is as follows:

  • Birth to 1 year: The diagnostic process includes a physical exam and CT scan with 3D reconstruction.
  • 2 to 6 months: Endoscopic craniosynostosis surgery is recommended.
  • 6 to 12 months: Calvarial vault remodeling is recommended.


Lambdoid craniosynostosis is treatable with early diagnosis and surgery. When left untreated, it’s possible for a child to experience increased intracranial pressure. This occurs when the pressure inside the skull increases and affects the brain. This can potentially lead to long-term complications, including:

  • Developmental delays
  • Head or facial abnormalities
  • Breathing problems
  • Vision disorders
  • Seizures
  • Low self-esteem


It is incredibly difficult to hear the news that your child has a serious birth defect and likely needs surgery on their skull. Finding ways to cope is essential for parents and caregivers. Research shows that caring for a child with craniosynostosis is stressful for parents, especially when their skull malformation is noticeable to others.

A 2020 survey of parents of children with craniosynostosis found that there are steps that parents can take to reduce stress during the treatment period. Because your child’s medical appointments can feel overwhelming, try to write down any questions you have ahead of time to avoid forgetting them. You may also want to bring a pen and paper with you to take notes.

Ask your medical team who you can call with questions in between appointments. Parents found that having a specialized nurse to call helped reduce fear and stress about their child’s condition. Finally, ask your child’s medical team about a local group or online community to join for support and education.


Lambdoid craniosynostosis is a rare type of craniosynostosis affecting the lambdoid suture, a flexible joint that runs along the back of the head. It causes an infant’s head to appear flat on the back and is therefore commonly confused with positional plagiocephaly, a benign condition that occurs if a baby spends too much time lying on their back. Lambdoid craniosynostosis is treated with surgery, and the earlier the diagnosis and treatment start, the better the outcome for the child.

Frequently Asked Questions

What causes craniosynostosis?

Craniosynostosis is usually considered a random birth defect and does not have a known cause. Researchers believe it is caused by a combination of genetic and environmental factors. Rarely, craniosynostosis is caused by a genetic disorder. 

Who is at risk of craniosynostosis?

Craniosynostosis is a common birth defect, and the exact cause of the condition is not yet understood. Possible risk factors for craniosynostosis include multiple babies in a pregnancy, large head size in utero, maternal thyroid disease, maternal smoking, and use of fertility treatments. If you are concerned about your risk factors, talk with your obstetrician. 

How common is craniosynostosis?

Craniosynostosis is a relatively common birth defect, affecting about one in every 2,500 live births.

What should you expect after lambdoid craniosynostosis surgery?

After undergoing surgery for lambdoid craniosynostosis, your child will stay in the hospital. Most babies spend one night in the intensive care unit and are then moved to a regular hospital room. After endoscopic craniosynostosis surgery, your child will need to wear a helmet for several months.

A Word From Verywell 

Lambdoid craniosynostosis is a rare type of craniosynostosis, a birth defect affecting the flexible joints in a baby’s skull. This condition is treatable with surgery and close follow-up with your child’s medical team.

Hearing that your child has a birth defect that requires surgery is scary and overwhelming for any parent. It’s helpful to remember that the condition is treatable. Always talk to your doctor about any questions or concerns. You may find it helpful to connect with a local support group or online community.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Carrie Madormo, RN, MPH
Carrie Madormo, RN, MPH, is a health writer with over a decade of experience working as a registered nurse. She has practiced in a variety of settings including pediatrics, oncology, chronic pain, and public health.