Macrocephaly In Babies: Causes, Diagnosis And Treatment

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Infants have varying head sizes. But sometimes there is disproportionate swelling of the skull and such big head in babies is called macrocephaly. It often indicates a problem.

What causes macrocephaly in babies and how do parents deal with it? In this article, MomJunction acquaints you with the reasons behind disproportionately large heads in infants and if there is a cure to the problem.

What Is Macrocephaly?

Macrocephaly, also called big head or large head syndrome, is a condition that causes an abnormal increase in the head circumference of the baby. Not all babies have the same head circumference. Therefore, physicians divide head circumferences into different percentiles (1).

If the circumference falls within the healthy range for their age and gender, then it is considered normal. Medical experts define macrocephaly as a condition where the baby’s head circumference (in centimeters or inches) is greater than the 98th percentile (2). There could be several reasons for macrocephaly.

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What Causes Macrocephaly In Babies?

Here are a few reasons why an infant could have a large head or develop one (3):

  1. Hydrocephalus is a condition that causes excessive cerebrospinal fluid to accumulate within the ventricles (spaces) of the brain. It is one of the most common brain disorders among infants (4). The excess fluid swells the skull. Hydrocephalus itself can occur due to several diseases ranging from congenital hydrocephalus to an injury or an infection.
  1. Nervous system infections can cause the brain and skull to enlarge in size. Examples include meningitis, an infection of the membrane covering the brain, and encephalitis, a severe inflammation of the brain tissue. Infections can develop due to pathogens such as bacteria and viruses.
  1. Rickets is caused due to the deficiency of vitamin D in the body. Rickets causes abnormalities of the skeletal system including bones of the skull. The skull can expand in size causing a big head (5).
  1. Brain disorders: Problems in the brain, such as a tumor, can cause a large head in babies. Some congenital deformities of the brain that can cause macrocephaly are hydranencephaly (lack of cerebrum) and megalencephaly (abnormal increase in brain matter).
  1. Genetic disorders: Defective genes can also cause macrocephaly. One of the most notable ones is the Sotos syndrome. It is a genetic disorder that affects the skeleton leading to many problems including the development of an unusually large head (6). Infants with autism may also display macrocephaly on attaining toddlerhood (7).

There could be situations where macrocephaly is a normal occurrence. In such cases, the baby will not display any health-related symptoms and will grow normally. There is nothing to worry in such situations. Nevertheless, if you suspect the infant’s skull to be going out of shape and disproportionate to the body, then do not hesitate to see the doctor.

[ Read: Autism Signs In Babies ]

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How Is Macrocephaly Diagnosed In Babies?

Physicians measure the height, weight, and head circumference of the infant and are likely to detect macrocephaly during a routine checkup in the first year of the baby’s life. Doctors will use the following tools to check for the underlying condition that led to a large head in babies:

  1. Physical examination: The doctor checks for the external appearance and feels the fontanelle (soft spot) on the baby’s skull. Some brain disorders like hydranencephaly can be diagnosed by illuminating the skull with a bright light. The doctor will also check for signs of internal bleeding that could suggest brain trauma.
  1. Observing other symptoms: Doctors check if the baby is irritable, has poor suckling reflex, displays extreme lethargy, and has missed any of the developmental milestones. These symptoms could indicate a disability-causing genetic disorder.
  1. Ultrasound: An ultrasound can give a quick analysis of what lies beneath the skull. It can help doctors decide the further course of testing.
  1. CT scan: Computerized tomography scan, or CT scan, takes multiple X-rays of the skull to create a three-dimensional image. It helps to check the outline of the skull and the point of deformity.
  1. MRI: Magnetic resonance imaging (MRI) uses a magnetic field to generate a highly accurate and elaborate image of the entire skull. While an MRI gives a detailed picture of macrocephaly, it requires the person to stay still.

So the doctors may use a bit of sedation to keep the infant still within the MRI scanner. Several hospitals now perform a “Quick MRI” without sedation, which is advisable for pediatric patients although this form of MRI has limited image rendering capabilities (8).

  1. Blood test and fluid collection: A blood test may help assess the presence of genetic problems. The doctor may even collect a sample of the cerebrospinal fluid from the base of the spinal cord, using a procedure called spinal tap. The fluid may also be obtained from the top layers of the brain depending on the condition of the skull.

Once your doctor has the diagnosis, they will recommend the best course of treatment.

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How Is Macrocephaly Treated?

The treatment of macrocephaly depends on the cause of the condition. Options include:

  1. Surgery is often the only option in several causes of macrocephaly. The type of surgery will vary according to the extent of swelling and the reason. For instance, hydrocephalus involves draining the cerebrospinal fluid into the abdomen where the body can absorb it. This surgery is called shunt surgery, where a silicon tube is placed in brain fluid on one side and abdominal cavity on another side. But it does not cure the condition, as hydrocephalus is a permanent condition. In the case of brain trauma, surgery may help rectify the problem entirely.
  1. The doctor may provide oral medications to control the swelling of the brain tissue. Deficiency diseases like rickets can be cured by giving the baby the right dose of the nutrient.
  1. Macrocephaly due to genetic disorders does not have a cure and can only be managed. Several infants with incurable macrocephaly encounter some form of cognitive and physical disability along with complications like seizures.

You can contact support organizations and trainers that specialize in dealing with infants with disabilities. Such resources can help train parents about coping with the condition and improving the infant’s quality of life.

[ Read: What Causes Hydrocephalus In Babies ]

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A large head in babies could be a normal or a result of a serious problem. In either case, your baby’s doctor is likely to diagnose the condition during a routine assessment. Management of macrocephaly is crucial in cases where the cause is incurable. Make use of the resources at hand to ensure a better quality of life for your baby.

Have something to share about macrocephaly in babies? Do tell us in the comment section below.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
1. Data Table of Infant Head Circumference-for-age Charts; Centers for Disease Control and Prevention
2. Macrocephaly; Children’s Hospital at Dartmouth-Hitchcock
3. Large Heads (Macrocephaly); The University of Chicago
4. About Hydrocephalus; Stanford Medicine
5. Vitamin D; University of Rochester
6. Sotos syndrome; U.S. National Library of Medicine
7. Macrocephaly Syndromes; University of Florida
8. K. Rozovsky et al., Fast-brain MRI in children is quick, without sedation, and radiation-free, but beware of limitations; National Center for Biotechnology Information


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Rohit Garoo

Rohit Garoo is a zoologist-botanist turned writer with over 8 years of experience in content writing, content marketing, and copywriting. He has also done an MBA in marketing and human resources and worked in the domains of market research and e-commerce. Rohit writes topics related to health, wellness and development of babies. His articles featured on several notable websites, including... more