Microcephaly

Microcephaly is a rare neurological disorder in which the circumference of an infant's head is significantly smaller than average for children of the same age and sex. Microcephaly may be present at birth (congenital) or develop later in infancy.

Microcephaly usually occurs when the brain fails to grow at a normal rate. As a result, the child's skull doesn't enlarge to its normal size. This disorder is often associated with mental retardation.

Causes of microcephaly may include:

• Fetal alcohol syndrome
• Decreased oxygen to the fetal brain (cerebral anoxia) due to pregnancy complications or complications during delivery
• Craniosynostosis — the premature fusing of the joints (sutures) between the bony plates that form an infant's skull
• Chromosomal abnormalities
• Infections of the fetus during pregnancy, such as toxoplasmosis, cytomegalovirus and measles (rubella)

There's no specific treatment for microcephaly. Treatment is usually directed at managing the signs and symptoms associated with the disorder. If microcephaly due to craniosynostosis is detected early, treatment may include surgical opening of the sutures to let the brain grow normally.

If you're concerned about the size of your child's head, talk to your doctor. Doctors use growth rate charts — similar to those for height and weight — to compare your child's head circumference with that of other children of the same age and sex.

It's important to note that heads with circumferences in the 1st, 2nd and 3rd percentiles are just small heads. Microcephaly is a head circumference that is significantly below the 1st percentile.