Microcephaly
What is microcephaly?
Microcephaly is a neurological disorder in which the circumference of the
head (the measured distance around the top) is smaller than average for an
infant’s size and age. The disorder can be present at birth or acquired during
the first few years of a child’s life. Microcephaly is often associated with
some degree of mental retardation. However, in 15 percent of the cases, the
child has normal intelligence. Microcephaly is rare, occurring from 1 per 6200
to 8500 births.
What causes microcephaly?
The growth of the skull is determined by the expansion of the brain.
Microcephaly occurs most often because the brain fails to grow at a normal rate.
This can be caused by a variety of conditions or exposure to harmful substances
during fetal development. Some of these causes include:
- Chromosomal disorders such as Down’s syndrome,
Cri du chat syndrome, Trisomy 13, and Trisomy 18
- Maternal viral infections such as rubella (German
measles), toxoplasmosis, and cytomegalovirus
- Maternal alcoholism or drug abuse
- Maternal diabetes
- Mercury poisoning
- Uncontrolled maternal PKU
- Maternal malnutrition
Acquired microcephaly might occur after birth due to various brain injuries
such as lack of oxygen or infection.
What are the symptoms of microcephaly?
Aside from a noticeably smaller head, the following are the most common
symptoms of microcephaly.
- High-pitched cry
- Poor feeding
- Convulsions
- Increased movement of the arms and legs (spasticity)
- Hyperactivity
- Developmental delays
- Mental retardation
As the child grows older, his or her face continues to grow while the skull
does not. This causes the child to develop a disproportionately large face, a
receding forehead and a loose, often wrinkled scalp. The rest of the body is
often underweight and proportionately smaller than normal.
How is microcephaly diagnosed?
Microcephaly can sometimes be diagnosed before birth by prenatal ultrasound.
In many cases, however, it might not be evident by ultrasound until the third
trimester, and therefore might not be seen on ultrasound performed earlier in
pregnancy.
Most of the time, the diagnosis will not be made until birth or later in
infancy. Along with noting that the baby's head circumference is much smaller
than normal, the doctor will perform a complete physical examination and obtain
a complete prenatal and birth history of the child. In the case of later
development of the disorder, the doctor might ask the parents about developmental
milestones such as crawling and walking, since microcephaly is frequently
accompanied by mental retardation.
How is microcephaly treated?
Generally there is no specific treatment for microcephaly. Since
microcephaly is a life-long condition that is not correctable, management of the
condition includes maximizing the child's capabilities at home and in the
community. Positive reinforcement will encourage the child to strengthen his or her
self-esteem and promote as much independence as possible.
The full extent of microcephaly is usually not completely understood
immediately after birth, but might be revealed as the child grows and develops.
A child born with microcephaly requires frequent examinations and diagnostic
testing by a doctor to monitor the development of the head as he or she
grows. The medical team works with the child's family to provide education and
guidance to improve the health and well-being of the child.
What is the prognosis for microcephaly?
Prognosis for microcephaly varies, and depends on the presence of other
existing medical conditions. In general, however, life expectancy for children
with microcephaly is reduced, and the prospects of attaining normal brain
function is poor.
©
Copyright 1995-2005 The Cleveland Clinic Foundation. All rights reserved
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