Microcephaly occurs when a baby’s head and brain are smaller than normal for the age of the baby.
Microcephaly is a rare, neurological condition caused by a variety of factors in which a baby’s head is much smaller than normal. “Micro” refers to small and “cephaly” to the head.
The size of a baby’s head is largely determined by brain growth. If a condition causes a baby’s brain to develop abnormally while the mother is pregnant, the brain may be smaller than normal. As a result, the baby’s head will be smaller.
Microcephaly can be present at birth (congenital) or it can develop after the baby is born (acquired).
Developmental and intellectual difficulties can occur because of a smaller brain, but the extent of the condition can range from mild to severe.
The following can be causes of microcephaly:
- Genetics – inherited chromosomal abnormalities, including Down syndrome, can cause microcephaly
Causes during pregnancy:
- Chicken pox in the pregnant mother – also called varicella
- Craniosynostosis – premature fusing of plates in the skull
- Cytomegalovirus – a type of herpesvirus
- Decreased oxygen to the baby’s brain during the pregnancy or birth
- Drugs or alcohol use
- Exposure to certain toxins or hazardous chemicals, such as methylmercury poisoning
- Rubella in the pregnant mother – also called German measles
- Severe malnutrition of the mother
- Toxoplasmosis - an infection caused by a parasite
- Untreated maternal PKU (phenylketornuria) – a birth defect that hampers the body's ability to break down the amino acid phenylalanine
- Zika virus – transmitted by mosquito bites and bodily fluid
Conditions after birth (acquired microcephaly):
- Lack of oxygen
- Brain injury
A small skull is the primary symptom of microcephaly. Other symptoms include:
- Feeding difficulties
- Hearing and vision problems
- Movement and balance problems