*Microcephaly facts medical author: Charles Patrick Davis, MD, PhD
- Microcephaly is a condition where the head (circumference) is smaller than normal.
- Microcephaly may be caused by genetic abnormalities or by drugs, alcohol, certain viruses, and toxins that are exposed to the fetus during pregnancy and damage the developing brain tissue. Unfortunately, a 2015-2016 outbreak of
Zika virus in Brazil has been associated with a large number of infants born with microcephaly. Epidemiological and some viral isolations suggest that pregnant women who get Zika virus have a high chance of fetal infection that may lead to microcephaly, although
a definitive link between Zika virus infection and microcephaly is not yet proven.
- Signs and symptoms of microcephaly may include a smaller than normal head circumference that usually remains smaller than normal as the child grows, dwarfism or short stature, delayed motor and speech functions, mental retardation, seizures, facial distortions, hyperactivity, balance and coordination problems, and other brain-related or neurological problems; although some with the disorder may develop normal intelligence.
- There is no treatment to change the head size; programs are available to help these individuals reach their maximum potential and genetic counseling may help explain the risk for microcephaly in future pregnancies. Women who are interested in becoming pregnant are being advised by the CDC and other agencies to avoid traveling to areas where Zika virus is found to reduce the chance of becoming infected while pregnant.
- Research on microcephaly is ongoing; for example, researchers found that amino acid therapy may reduce seizure activity in some patients. There is no vaccine available for Zika virus; researchers predict a vaccine will take three to five years to develop.
What is microcephaly?
Microcephaly is a medical condition in which the circumference of the head is smaller than normal because the brain has not developed properly or has stopped growing. Microcephaly can be present at birth or it may develop in the first few years of life.
What causes microcephaly?
It is most often caused by genetic abnormalities that interfere with the growth of the cerebral cortex during the early months of fetal development. It is associated with Down's syndrome, chromosomal syndromes, and neurometabolic syndromes. Babies may also be born with microcephaly if, during pregnancy, their mother abused drugs or alcohol, became infected with a cytomegalovirus, rubella (German measles), or varicella (chicken pox) virus, was exposed to certain toxic chemicals, or had untreated phenylketonuria (PKU).
Babies born with microcephaly will have a smaller than normal head that will fail to grow as they progress through infancy.
What are microcephaly symptoms and signs?
Depending on the severity of the accompanying syndrome, children with microcephaly may have
- impaired cognitive development,
- delayed motor functions and speech,
- facial distortions,
- dwarfism or short stature,
- difficulties with coordination and balance, and
- other brain or neurological abnormalities.
Some children with microcephaly will have normal intelligence and a head that will grow bigger, but they will track below the normal growth curves for head circumference.
Stages of Pregnancy: Week by Week
Zika Virus and Pregnancy
Zika Blamed for Increase in Cases of Microcephaly
Zika virus infections first arose in Brazil in May 2015. Pregnant women, especially those in the first and early second trimester, in areas where the disease is prevalent should try to avoid any mosquito bites. Officials in Brazil are concerned since almost 4,000 babies (very unusually high number as compared to similar time periods in which only about 150 babies were diagnosed with microcephaly) have been born with microcephaly since May 2015. In addition, Dr. R. Coeli, a pediatrician in Brazil, has reported Zika viruses isolated from the amniotic fluid of two women and one infant's brain and heart tissue -- results she concludes that tie the Zika virus to microcephaly development. Officials have taken the unusual step to recommend women avoid pregnancy until the cause of the increase in microcephaly is definitively determined.
Is there any treatment for microcephaly?
There is no treatment for microcephaly that can return a child's head to a normal size or shape. Treatment focuses on ways to decrease the impact of the associated deformities and neurological disabilities. Children with microcephaly and developmental delays are usually evaluated by a pediatric neurologist and followed by a medical management team. Early childhood intervention programs that involve physical, speech, and occupational therapists help to maximize abilities and minimize dysfunction. Medications are often used to control seizures, hyperactivity, and neuromuscular symptoms. Genetic counseling may help families understand the risk for microcephaly in subsequent pregnancies.
What is the prognosis for microcephaly?
Some children will only have mild disability. Others, especially if they are otherwise growing and developing normally, will have normal intelligence and continue to develop and meet regular age-appropriate milestones.
What research is being done on microcephaly?
The National Institute of Neurological Disorders and Stroke (NINDS) conducts research relating to microcephaly in its laboratories at the National Institutes of Health (NIH) and supports additional research through grants to major medical institutions across the country. A small group of researchers studying a rare neurometabolic syndrome (3-PGDH), which causes microcephaly, have successfully used amino acid replacement therapy to reduce and prevent seizures.
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National Institute of Neurological Disorders and
Stroke, National Institutes of Health.