Microcephaly is a rare neurological condition affecting 2-12 babies per 10,000 live births in the United States every year.1
The condition presents as having a smaller than average head size as compared to babies who fall into the same age and sex categories. Microcephaly often results in a smaller brain size.1,2
Abnormal brain development frequently accompanies microcephaly and is often present in combination with other major birth defects, although it can also be the only abnormality present.1,2
Microcephaly can be present at birth due to abnormal brain growth in utero or may be diagnosed after birth as a result of poor brain growth.1,2
Fast facts on microcephaly
Here are some key points about microcephaly. More detail and supporting information is in the main article.
- Microcephaly is a rare condition, affecting 2-12 of every 10,000 live births in the US every year
- The condition can be present at birth or develop afterward
- The risk of microcephaly is increased by exposure to infections such as rubella during pregnancy
- Microcephaly is often accompanied by other serious medical conditions such as seizures, developmental delay and balance problems
- The severity of microcephaly and its symptoms varies from person to person
- Microcephaly can be diagnosed with an ultrasound scan during pregnancy
- There is currently concern over the possible link between the Zika virus and its relationship with the development of microcephaly
- The Centers for Disease Control and Prevention (CDC) have developed travel guidelines for pregnant women when considering travel to countries affected by the Zika virus.
Causes of microcephaly
The cause of microcephaly is not fully understood. However, there are certain conditions which may predispose an infant to develop the condition.1
Microcephaly can be present at birth following abnormal brain development in the uterus.
Conditions that pose a risk for developing microcephaly include:1,2
- Genetic or chromosomal abnormalities such as Down syndrome
- Infections such as rubella, toxoplasmosis, cytomegalovirus, chickenpox and possibly the Zika virus
- Severe malnutrition
- Craniosynostosis (premature skull suture line fusing)
- Cerebral anoxia (decreased oxygen delivery to the fetal brain)
- Maternal uncontrolled phenylketonuria (PKU), a birth defect that restricts the body's ability to break down a specific amino acid.
Environmental factors can also increase the risk of microcephaly. If a fetus is exposed to drugs, alcohol or toxins while in the womb, the risk of the baby developing a brain abnormality is higher.2
Symptoms of microcephaly
Infants with microcephaly will have a significantly smaller than average head size based on measurements of children in the same age and sex category. The size of the head is determined by measuring the circumference around the top of the head.1,2
While some children are born with small heads, children with microcephaly are significantly smaller than the average, and can even be smaller than the first percentile for an age group.2
Another characteristic feature - typically seen in more severe cases of microcephaly - is a backward-sloping forehead.2
Serious complications secondary to microcephaly can be serious and lifelong; at times, secondary conditions can be life-threatening.1
Complications of microcephaly include:1,2
- Developmental delays
- Intellectual disabilities
- Mental retardation
- Facial distortions
- Movement and balance disorders
- Feeding problems
- Hearing loss
- Vision problems.
On the next page, we look at tests and diagnosis of microcephaly and the available treatment options for the condition.