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Microcephaly in infants and children: Etiology and evaluation

Julie A Boom, MD
Section Editors
Jan E Drutz, MD
Helen V Firth, DM, FRCP, DCH
Marc C Patterson, MD, FRACP
Deputy Editor
Mary M Torchia, MD


The measurement of head circumference (also called occipitofrontal circumference [OFC]), a direct reflection of head growth, is an important step in the evaluation of childhood growth and development. Deviations from normal head growth may be the first indication of an underlying congenital, genetic, or acquired problem (eg, congenital infection, genetic syndrome) [1-4]. Many genetic conditions are associated with an abnormal pattern of head growth; the earlier these conditions are detected, the earlier appropriate treatment, services, and genetic counseling can be provided [5].

The etiology and evaluation of microcephaly in infants and children will be reviewed here. The etiology and evaluation of macrocephaly and the clinical genetics approach to microcephaly are discussed separately. (See "Microcephaly: A clinical genetics approach" and "Macrocephaly in infants and children: Etiology and evaluation", section on 'Etiology'.)


Occipitofrontal circumference (OFC) should be measured at health maintenance visits between birth and three years of age and in any child with neurologic symptoms or developmental complaints. The technique for measuring head circumference (picture 1) is discussed separately. (See "The pediatric physical examination: General principles and standard measurements", section on 'Head circumference'.)

OFC measurements are most informative when plotted over time [6]. Normal head growth in infants and children and reference standards for monitoring head growth in healthy children are discussed separately. In the United States, the Centers for Disease Control and Prevention (CDC) recommend that the WHO growth standards ( (figure 1A-B) and (calculator 1)) be used for children age zero to two years and the CDC growth charts ( (figure 2A-B) and (calculator 2)) be used for children age two to three years [7]. (See "Normal growth patterns in infants and prepubertal children", section on 'Head growth' and "The pediatric physical examination: General principles and standard measurements", section on 'Head circumference'.)


Microcephaly — Given that microcephaly is a sign rather than a diagnosis, we define microcephaly with qualifying terms:

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Literature review current through: Dec 2017. | This topic last updated: Aug 02, 2017.
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