Macrocephaly

Macrocephaly (or "big head") is a very common reason for referral to a pediatric neurosurgeon. Children with macrocephaly have a head circumference (the measurement around the widest part of the head) that is greater than the 98th percentile. Sometimes a large head could mean that there is a problem in the brain which might require surgery.

 

Evaluation

Your pediatric neurosurgeons will take a careful medical history of your child, including past head measurements provided by your pediatrician. It is also important to know if other members of your family also have large heads. A neurological exam will also be performed.

 

Your child's pediatrician may have ordered special tests to look at the brain known as an ultrasound or CT (computed tomography) scan. If not, a special test, called a "Quick-Brain MRI (Magnetic Resonance Imaging)" may be ordered to evaluate your child's brain. This test looks for extra fluid in the brain (also known as hydrocephalus) which would require treatment. This is a radiologic test very similar to a CT scan, but does not require radiation. It takes about 10 minutes to complete.

 

Children with macrocephaly may have a small amount of fluid between the brain and skull. This is sometimes referred to as "benign extra-axial collections of infancy or benign external hydrocephalus." This is a very common finding in children with large heads and usually requires no treatment other than careful follow-up. Most children "outgrow" this extra fluid by early childhood.

 

Additional evaluation may be necessary if there are any concerning findings on history, physical exam, or radiographic imaging.

 

Follow-up

Most children with macrocephaly and a normal Quick-Brain MRI will be scheduled for a repeat evaluation and head measurement check in 3 months. Repeat imaging is usually not needed at that time. In addition, your pediatrician will keep a close eye on your child's head measurements and alert your neurosurgeon if there are any new concerns.

 

Parents should watch their children and report any of the following to their pediatrician or neurosurgeon:

 

A bulging soft-spot (fontanel)

Vomiting or poor feeding

Abnormal eye movements

Excessive sleepiness

Excessive irritability

 

Microceophaly

Microcephaly is a birth defect where a baby’s head is smaller than expected when compared to babies of the same sex and age. Babies with microcephaly often have smaller brains that might not have developed properly.

 

What is microcephaly?

 

Microcephaly is a condition where a baby’s head is much smaller than expected. During pregnancy, a baby’s head grows because the baby’s brain grows. Microcephaly can occur because a baby’s brain has not developed properly during pregnancy or has stopped growing after birth, which results in a smaller head size. Microcephaly can be an isolated condition, meaning that it can occur with no other major birth defects, or it can occur in combination with other major birth defects.

 

What is severe microcephaly?

 

Severe microcephaly is a more serious, extreme form of this condition where a baby’s head is much smaller than expected. Severe microcephaly can result because a baby’s brain has not developed properly during pregnancy, or the brain started to develop correctly and then was damaged at some point during pregnancy.

 

Other Problems

 

Babies with microcephaly can have a range of other problems, depending on how severe their microcephaly is. Microcephaly has been linked with the following problems:

 

Seizures

Developmental delay, such as problems with speech or other developmental milestones (like sitting, standing, and walking)

Intellectual disability (decreased ability to learn and function in daily life)

Problems with movement and balance

Feeding problems, such as difficulty swallowing

Hearing loss

Vision problems

These problems can range from mild to severe and are often lifelong. Because the baby’s brain is small and underdeveloped, babies with severe microcephaly can have more of these problems, or have more difficulty with them, than babies with milder microcephaly. Severe microcephaly also can be life-threatening. Because it is difficult to predict at birth what problems a baby will have from microcephaly, babies with microcephaly often need close follow-up through regular check-ups with a healthcare provider to monitor their growth and development.

 

Occurrence

 

Microcephaly is not a common condition. State birth defects tracking systems have estimated that microcephaly ranges from 2 babies per 10,000 live births to about 12 babies per 10,000 live births in the Unites States.1

 

Causes and Risk Factors

 

The causes of microcephaly in most babies are unknown. Some babies have microcephaly because of changes in their genes. Other causes of microcephaly, including severe microcephaly, can include the following exposures during pregnancy:

 

Certain infections during pregnancy, such as rubella, toxoplasmosis, or cytomegalovirus

Severe malnutrition, meaning a lack of nutrients or not getting enough food

Exposure to harmful substances, such as alcohol, certain drugs, or toxic chemicals

Interruption of the blood supply to the baby’s brain during development

Some babies with microcephaly have been reported among mothers who were infected with Zika virus while pregnant. CDC scientists announced that enough evidence has accumulated to conclude that Zika virus infection during pregnancy is a cause of microcephaly and other severe fetal brain defects.

 

CDC continues to study birth defects, such as microcephaly, and how to prevent them. If you are pregnant or thinking about becoming pregnant, talk with your doctor about ways to increase your chances of having a healthy baby.