Microcephaly
Definition
Microcephaly describes a head size significantly below normal for a person's age and sex, based on standardized charts. Head size is measured as the distance around the top of the head.
Considerations
Microcephaly most often occurs because of failure of the brain to grow at a normal rate. Skull growth is determined by brain expansion, which takes place during the normal growth of the brain during pregnancy and infancy.
Conditions that affect brain growth can cause microcephaly, including infections, genetic disorders, and severe malnutrition.
Causes
Primary Causes:
- Cornelia de Lange syndrome
- Cri du chat syndrome
- Down syndrome
- Rubinstein-Taybi syndrome
- Seckel syndrome
- Smith-Lemli-Opitz syndrome
- Trisomy 13
- Trisomy 18
Secondary Causes:
- Uncontrolled phenylketonuria (PKU) in the mother
- Methylmercury poisoning
- Congenital rubella
- Congenital toxoplasmosis
- Congenital CMV
- Use of certain drugs during pregnancy
- Malnutrition
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