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.
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.
Conditions that pose a risk for developing microcephaly include:
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.
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.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.Serious complications secondary to microcephaly can be serious and lifelong; at times, secondary conditions can be life-threatening.
Complications of microcephaly include:
Seizures
Developmental delays
Intellectual disabilities
Mental retardation
Hyperactivity
Facial distortions
Dwarfism
Movement and balance disorders
Feeding problems
Hearing loss
Vision problems.
Diagnosis of microcephaly
Occasionally, the presence of microcephaly can be seen on a second or third trimester ultrasound and diagnosed prior to birth.To obtain a diagnosis of microcephaly after birth, the child will undergo a comprehensive examination process.
The diagnostic process for microcephaly can include:
A physical exam, including head circumference evaluation
Prenatal examination
Birth examination
Taking a family history and evaluating the parents' head sizes
Charting head growth over time.
Doctors could also opt to use a CT scan (computerized tomography), MRI (magnetic resonance imaging) or blood testing to evaluate for the presence and cause of developmental delay.CT scan and MRI will also provide the health care team with information regarding the presence of an infection in utero that may have caused structural brain changes.
Treatments for microcephaly
There is currently no treatment or cure for microcephaly. Instead, treatment focuses on interventions to manage the condition and alleviate accompanying conditions such as seizures.Mildly microcephalic babies typically only require routine check-ups. Those with a more severe form of the condition, however, may require early childhood intervention programs to strengthen and maximize the child's physical and intellectual capabilities, including speech, physical and occupational therapies.A condition called craniosynostosis can cause microcephaly. In cases of craniosynostosis, the joints between the bones of a baby's skull fuse together prematurely, preventing the brain from growing properly. However, this condition is typically reversible with surgery to help reshape the skull.
Prevention of microcephaly
Speak with your health care provider about your personal risks for having a baby with microcephaly and what you can do to lower that risk. In any pregnancy, it is important to reduce the risk of complications by avoiding the consumption of alcohol, drugs and other toxins.Avoidance of contracting chickenpox, rubella, cytomegalovirus and toxoplasmosis is also typically recommended.
Possible connection between microcephaly and Zika virus.Due to the recent concern over the risk of microcephaly and Zika virus, the CDC recommend that pregnant women avoid travel to regions affected by the spread of the Zika virus. These regions include
Bolivia,
Brazil,
Cape Verde,
Colombia,
Ecuador,
El Salvador,
French Guiana,
Guadeloupe,
Guatemala,
Guyana,
Haiti,
Honduras,
Martinique,
Mexico,
Panama,
Paraguay,
Saint Martin,
Suriname,
Samoa,
Venezuela,
Puerto Rico,
US Virgin Islands,
Dominican Republic.