Macrocephaly

Macrocephaly is a condition in which the circumference of the human head is abnormally large for age and sex. It can be harmless, and may simply run in a family as an inherited trait, in which case the enlarged brain is described as megalencephaly. It can also be pathological, arising from an enlarged brain, from excess cerebrospinal fluid in hydrocephalus, from overgrowth of the skull bones, or from a wide range of genetic overgrowth syndromes, leukodystrophies and metabolic disorders. Environmental events such as infection or bleeding around the infant brain are also linked to it. Clinicians separate syndromic cases, where another notable condition is present, from nonsyndromic ones, and a child found to have an enlarged head is usually followed with further tests to learn whether a particular disorder accompanies it.