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Infants whose head sizes are smaller than 97 percent of children, a condition called microcephaly, are at risk of developing neurologic and cognitive disorders, according to a new guideline by the American Academy of Neurology (AAN). Published in Neurology in September 2009, the guideline recommends early screening for microcephaly, while acknowledging that many children with small head size develop normally.
Microcephaly usually occurs when the brain fails to grow at a normal rate. As a result, the infant's skull fails to expand normally. Some causes of the condition include genetic abnormalities, malnutrition, and infections such as rubella or chickenpox during pregnancy. It affects 25,000 infants in the U.S. each year. Though it is not a disease, microcephaly may be a signpost of conditions such as epilepsy, cerebral palsy, mental retardation, and eye and ear disorders.
Strong evidence shows that children with microcephaly are at risk for developmental delay and learning disorders. It is vital for doctors to recognize microcephaly and check the child for these associated problems, which often require special treatments that should be started as soon as possible, says lead guideline author Stephen Ashwal, M.D, a child neurologist at Loma Linda University School of Medicine in Loma Linda, CA. Parents are advised to see a doctor even if small head size runs in the family, because of these related risks.
The results of genetic testing and brain scans such as an MRI and CT scan can determine the cause of microcephaly and provide doctors with accurate advice for parents. While there is no specific treatment for microcephaly, the related disorders can be managed with treatment.
To view a video demonstrating how a doctor measures a child's head circumference for microcephaly, visit the AAN's YouTube channel at youtube.com/AANChannel .