Abnormal brain development frequently accompanies microcephaly. The condition can often occur alongside other major birth defects. Microcephaly can, however, be the only abnormality present.
The condition occurs in between 2 and 12 in every 10,000 live births each year in the United States.
In this article, we explore the causes, diagnosis, and treatment of microcephaly.
Microcephaly is a shrinking of the brain and skull. A range of genetic conditions, infections, and diseases can cause it.
The cause of microcephaly is not always clear. The condition may develop at birth or in the first few years of life.
However, certain conditions might have a relationship with its development.
Conditions that increase the risk of developing microcephaly include:
- genetic or chromosomal abnormalities, such as Down syndrome
- infections during pregnancy, such as rubella, toxoplasmosis, cytomegalovirus, chickenpox, and possibly the Zika virus
- severe malnutrition
- craniosynostosis, or premature fusing of the skull suture line
- cerebral anoxia, a condition involving a decrease in oxygen delivery to the brain of a fetus
- maternal uncontrolled phenylketonuria (PKU), a congenital anomaly that restricts the body's ability to break down a specific amino acid
Environmental factors can also increase the risk of microcephaly. If, while in the womb, the mother exposes a fetus is exposed to illicit drugs, alcohol, or toxins, the risk of the infant developing a brain abnormality is higher.
While the defining feature of microcephaly is decreased head circumference, the condition has other effects on health that can limit quality of life and impair development.
The effects of microcephaly on development can range from mild to severe, and might include:
- delayed development, such as learning to speak, stand, sit, or walk at a later age than other children at a similar stage
- learning difficulties
- movement and balance issues
- a high-pitched cry
- issues with feeding, such as dysphagia, or difficulty swallowing
- hearing loss
- reduced vision from lesions on the retina, the area at the back of the eye
- distorted facial features and expressions
- short stature
In severe cases, microcephaly may be life-threatening.
CT scans can help identify microcephaly.
Occasionally, a doctor may detect the presence of microcephaly on a second- or third-trimester ultrasound and diagnose the anomaly before the birth of the infant.
For a child to receive a diagnosis of microcephaly after birth, they will undergo an in-depth examination process.
The diagnostic process for microcephaly can include:
- a physical exam, including an evaluation of head circumference
- family history and evaluating the head sizes of the parents
- charting head growth over time
Once a doctor diagnoses microcephaly, doctors could also use CT or MRI scans and blood tests to evaluate the severity and cause of the microcephaly, as well as any other associated conditions.
Some of these tests might also provide the healthcare team with information about the presence of an infection in utero that may have caused structural brain changes.
No treatment or cure is currently available for microcephaly.
Instead, treatment focuses on managing the condition and relieving linked health problems, such as seizures. If an ongoing process is contributing to the microcephaly, such as malnutrition, healthcare professionals will also address this.
Infants with mild microcephaly typically only require routine check-ups. However, those with a more severe form of the condition may require early childhood intervention programs to strengthen their physical and intellectual capabilities.
These programs will often include speech, physical, and occupational therapies.
A condition called craniosynostosis can cause microcephaly. In cases of craniosynostosis, the joints between the bones of an infant skull fuse together prematurely, preventing the brain from growing fully.
However, this condition is typically reversible with surgery that helps reshape the skull.
While treatment options manage rather than cure microcephaly, some people with the condition have normal cognitive function and a head that grows larger over time despite remaining smaller than the usual growth pattern.
However, people with microcephaly as a result of Zika often have a more severe presentation that might even need intensive care on a lifelong basis.
Speak with your healthcare provider about the personal risks of having a child with microcephaly and the steps you can take to lower that risk.
In any pregnancy, reducing the risk of complications by avoiding alcohol, drugs, and other toxins is important.
Chickenpox, rubella, cytomegalovirus, and toxoplasmosis have links to the condition, so take preventative measures against these diseases.
Possible connection between microcephaly and Zika virus
The Zika virus has links to microcephaly.
Due recent concerns over the risk of microcephaly and Zika virus, the Centers for Disease Control (CDC) recommend that women who are pregnant avoid traveling to regions in which the disease has a presence.
Click here for a full, up-to-date rundown of countries that the CDC cites as presenting a risk of Zika.
Dr. Mark DeFrancesco, President of the American College of Obstetricians and Gynecologists (ACOG), advised the following in a statement supporting the travel guidelines set in place by the CDC.
"Travel to regions with ongoing Zika virus outbreaks is not recommended for women who are pregnant or women who are considering pregnancy."
Information on Zika is developing and changing fairly rapidly. Follow this link for the most recent statements and recommendations from ACOG.
To learn more about the CDC's travel recommendations, please visit their travel health notices web page.