| Microcephaly is a medical condition in which | | | | underweight and dwarfed. Development of motor |
| the circumference of the head is smaller than | | | | functions and speech may be delayed. |
| normal because the brain has not developed | | | | Hyperactivity and mental retardation are |
| properly or has stopped growing. | | | | common occurrences, although the degree of |
| Microcephaly can be present at birth or it | | | | each varies. Convulsions may also occur. |
| may develop in the first few years of life. | | | | Motor ability varies, ranging from clumsiness |
| It is most often caused by genetic | | | | in some to spastic quadriplegia in others. |
| abnormalities that interfere with the growth | | | | |
| of the cerebral cortex during the early | | | | Causes of Microcephaly |
| months of fetal development. It is | | | | |
| associated with Down's syndrome, chromosomal | | | | Microcephaly can occur alone or in |
| syndromes, and neurometabolic syndromes. | | | | association with other health problems, and |
| Babies may also be born with microcephaly if, | | | | may occur from inheritance of an autosomal |
| during pregnancy, their mother abused drugs | | | | recessive, or rarely, an autosomal dominant |
| or alcohol, became infected with a | | | | gene. Acquired microcephaly may occur after |
| cytomegalovirus, rubella (German measles), or | | | | birth due to various brain injuries such as |
| vermicelli (chicken pox) virus, was exposed | | | | lack of oxygen or infection. |
| to certain toxic chemicals, or had untreated | | | | |
| phenylketonuria (PKU). Babies born with | | | | Microcephaly may be inherited but the gene is |
| microcephaly will have a smaller than normal | | | | considered to be extremely rare. In the |
| head that will fail to grow as they progress | | | | general population, microcephaly due to |
| through infancy. | | | | genetic factors occurs in 1 in 30,000 to |
| | | | 50,000 live births, and in 1 per 10,000 |
| In many cases, microcephaly may not be | | | | births due to other causes. In some |
| evident by ultrasound until the third | | | | populations, frequency may be as high as 1 in |
| trimester, and, therefore, may not be seen on | | | | 2,000 births. |
| ultrasounds performed earlier in pregnancy. | | | | |
| The diagnosis of microcephaly may be made at | | | | Microcephaly can also be caused if the mother |
| birth or later in infancy. The baby's head | | | | has an infection while pregnant or if she is |
| circumference is much smaller than normal. | | | | exposed to harmful substances during early |
| During the physical examination, the | | | | pregnancy, such as x-rays (a type of energy) |
| physician obtains a complete prenatal and | | | | or chemicals. Another cause of microcephaly |
| birth history of the child. In older babies | | | | is if the bones of the skull come together |
| and children, the physician may also ask if | | | | too early. For genetic (inherited) causes of |
| there is a family history of microcephaly or | | | | microcephaly, see the next section. |
| other medical problems. The physician will | | | | |
| also ask about developmental milestones since | | | | Microcephaly is either caused by exposure to |
| microcephaly can be associated with other | | | | harmful substances during the fetal |
| problems, such as mental retardation. | | | | development, or it may be associated with |
| | | | genetic problems or syndromes that may have a |
| Infants with microcephaly are born with | | | | tendency to run in families. |
| either a normal or reduced head size. | | | | |
| Subsequently the head fails to grow while the | | | | Microcephaly most often occurs because of |
| face continues to develop at a normal rate, | | | | failure of the brain to grow at a normal |
| producing a child with a small head and a | | | | rate. Skull growth is determined by brain |
| receding forehead, and a loose, often | | | | expansion, which takes place during the |
| wrinkled scalp. As the child grows older, the | | | | normal growth of the brain during pregnancy |
| smallness of the skull becomes more obvious, | | | | and infancy. |
| although the entire body also is often | | | | |