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What is Microcephaly?

A baby's hand in an adult hand.

Microcephaly is a rare neurological disorder in which a child’s brain does not fully develop. The resultant head size is substantially smaller than expected. Microcephaly can be present at birth or may be acquired in the first years of life.

Children with microcephaly generally have differing degrees of intellectual disability, though a small percentage of children will not experience any developmental delays. Children with this condition may also have delayed speech and motor functions, dwarfism or short stature, vision and hearing deficiencies, and/or other problems associated with neurological abnormalities.

There are many potential causes for microcephaly, including:

  • Maternal prenatal infections, including rubella and Zika virus
  • Chromosomal disorders, including Down syndrome
  • Craniosynostosis, a birth defect identified by the premature closure of one or more of the joints between the bones of the skull before brain growth is complete
  • Bacterial meningitis
  • A mother’s use of drugs or alcohol during pregnancy
  • Chemical or radiation exposure

For more detailed information about microcephaly, including symptoms, diagnosis and prevention, visit the Johns Hopkins Children's Center website

Key Facts about Microcephaly

  • Microcephaly occurs most often when the brain fails to grow at a normal rate; the skull’s growth is determined by the brain’s size.
  • There is no treatment to reverse microcephaly, except for surgery for craniosynostosis. Intervention programs with speech, occupational and physical therapists can help affected children.
  • In cases of microcephaly with a genetic link, genetic counselors can help determine risk of microcephaly.

Treatment for Microcephaly at Johns Hopkins

At the Johns Hopkins Children’s Center, children with microcephaly are cared for by the Division of Pediatric Neurology. Depending on individual diagnosis, pediatric neurosurgery and genetics may also be involved with treatment. Many children with this condition will continue to be seen at the Kennedy Krieger Institute