What causes microcephaly? 3 possible conditions
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Infant growth is measured in a number of ways. Height (length) and weight, for instance, are common measures used by your doctor to determine if your infant is growing normally. Another measure of infant growth is head circumference, or the size of your baby’s head. Measurement of your baby’s head size is important because it indicates that your baby’s brain is growing properly. If your baby’s brain is not growing properly, he or she may have a condition known as microcephaly.
Microcephaly is a condition in which your baby’s head is smaller than that of other babies of the same age and gender. This condition may be present when your baby is born, or it may develop in the first two years of life. It has no cure. Early diagnosis and treatment, however, can improve the outlook for your child.
This condition is caused by abnormal brain development. Abnormal brain development can occur while the fetus is still in the womb or it can occur in infancy. Genetic conditions can also contribute to the development of microcephaly.
Genetic conditions that can cause microcephaly include:
Cornelia de Lange syndrome—this disorder slows growth inside and outside of the womb. Severe intellectual problems, arm and hand abnormalities, and facial distinctions (eyebrows that grow together in the middle, low-set ears, small teeth and nose) are common.
Down syndrome (Trisomy 21)—a condition characterized by cognitive delays, mild to moderate intellectual disability, distinctive facial features (almond-shaped eyes, round face, small features), and weak muscles.
Cri-du-chat (cat’s cry) syndrome—infants with this condition have a distinct, high-pitched cry, similar to that of a cat. Intellectual disability, low birth weight, weak muscles, and certain facial features (wide-set eyes, small jaw, low-set ears) are common.
Rubinstein-Taybi syndrome—infants with this uncommon condition are shorter than normal, have large thumbs and toes, distinctive facial features, and have intellectual disabilities. Infants with the severe form of this condition often do not survive past childhood.
Seckel syndrome—this rare condition causes growth delays in and out of the womb. Common characteristics include mental retardation and certain facial features (narrow face, beaklike nose, and a sloping jaw).
Smith-Lemli-Opitz syndrome—infants with this condition have intellectual disabilities and behavioral disabilities that mirror autism. Early signs of this disorder include feeding difficulties, slow growth, and combined second and third toes.
Trisomy 18 (Edward’s syndrome)—This condition is characterized by slow growth in the womb, low birth weight, and an irregularly shaped head. Organ defects are common as well. Infants usually do not survive past the first month of life.
Exposure to Viruses, Drugs, or Toxins
Microcephaly may also be caused by exposure of the fetus to certain viruses, drugs, or toxins. Examples include:
The use of alcohol or drugs by the mother can cause microcephaly.
Methylmercury poisoning—methylmercury is used as a preservative in seed grain food for animals. It can also form in water, leading to contaminated fish. Poisoning occurs when a person eats meat from an animal that has been fed seed grain or when a person eats contaminated seafood. A fetus exposed to this poison may develop brain and spinal cord damage.
Congenital rubella—If a mother contracts the virus that causes German measles (rubella) within a fetus’s first three months, her baby may develop severe problems. These problems include deafness, mental retardation, and seizures. This condition is not very common, however, with today’s rubella vaccine.
Congenital toxoplasmosis—If a mother is infected with the parasite Toxoplasma gondii (found in cat feces and uncooked meat), it can harm the developing baby. Babies can be born prematurely with many physical problems, including seizures and hearing and vision loss.
Congenital cytomegalovirus—A mother passes this virus to her fetus through the placenta. Other young children are common carriers of this virus, which can cause jaundice, rashes, and seizures in infants. Pregnant women should take precautions by washing hands frequently and not sharing utensils with children under 6.
Uncontrolled phenylketonuria (PKU) in the mother—If a mother has the gene for PKU, it is important that she follow a low phenylalanine diet. Too much of this substance, found in milk, eggs, and aspartame sweeteners, can harm a developing baby whose mother has the PKU gene.
Microcephaly may also be caused by certain complications that occur during delivery. Decreased oxygen to the fetal brain can increase the likelihood of an infant developing this disorder. Severe malnutrition of the mother may also increase the chances that an infant will develop microcephaly.
Children diagnosed with this condition will have complications that range from mild to severe. Children with mild complications may have normal intelligence. However, their head circumference will always be small for their age and gender.
Children with more severe complications may experience:
- mental retardation
- delayed motor function
- delayed speech
- facial distortions
- dwarfism (short stature)
- difficulty with coordination and balance
Your doctor can diagnose this condition by tracking your baby’s growth and development. When your baby is born, his or her head circumference will be measured. Your doctor will place a measuring tape around your baby’s head and will record its size. If your doctor notes abnormalities, he or she may make a diagnosis.
Your baby’s head will continue to be measured at routine well-baby exams during the first two years of life. Your doctor will also keep records of your baby’s growth. These records will be used to track your baby’s growth and development, which will help to detect any abnormalities.
Although your doctor may diagnose microcephaly, you should note any changes in your baby’s development that occur between office visits. You’ll want to record any changes in your baby’s growth and tell your baby’s doctor at your next appointment.
There is no cure. Treatment for children with the condition focuses on managing any resulting complications.
Children with delayed motor function may benefit from occupational therapy. Children with delayed language development may benefit from speech therapy. These therapies will help build and strengthen your child’s natural abilities. If your child develops certain complications, such as seizures or hyperactivity, your physician may also prescribe medication to treat them.
If the cause is genetic, you may not be able to prevent it. Parents who have a child with the condition may want to seek genetic counseling before having another child.
Proper prenatal care and avoiding alcohol and drug use during pregnancy are important for preventing the condition as well. Prenatal care can help diagnose conditions such as uncontrolled PKU in the mother.
If your child is diagnosed with this condition, you may not know how to help your child or what to expect as he or she grows. In order to help your child, you will need support. Finding a doctor and care team that can help you with decision-making is important. You may also want to seek the help of other families facing the same challenges. Support groups and online communities may be helpful for locating resources and for helping you to cope.
- Dugdale III, D. C. & Kaneshiro, N. K. (2011, November 13). Microcephaly. National Library of Medicine – National Health Institutes. Retrieved June 24, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/003272.htm
- Genetic Conditions—Genetics Home Reference. (2012, June 25). U.S. National Library of Medicine.Retrieved July 3, 2012, from http://ghr.nlm.nih.gov/BrowseConditions
- Kaneshiro, N. K. (2011, June 1). Congenital Cytomegalovirus. National Library of Medicine – National Health Institutes. Retrieved July 3, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/001343.htm
- Kaneshiro, N.K. (2011, June 1). Congenital Rubella. National Library of Medicine – National Health Institutes. Retrieved July 3, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/001658.htm
- Lee, K. G. (2011, June 17). Phenylketonuria. National Library of Medicine – National Health Institutes. Retrieved July 3, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/001166.htm
- Lee, K. G. (2011, June 18). Congenital Toxoplasmosis. National Library of Medicine – National Health Institutes. Retrieved July 3, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/001360.htm
- Microcephaly. (2012, May 30). Mayo Clinic. Retrieved June 24, 2012, from http://www.mayoclinic.com/health/microcephaly/DS01169
- NINDS Microcephaly information page. (2008, October 29). National Institute of Neurological Disorders and Stroke. Retrieved June 24, 2012, from http://www.ninds.nih.gov/disorders/microcephaly/microcephaly.htm
- Office of Rare Diseases Research. (n. d.). Seckel Syndrome. Genetic and Rare Diseases Information Center.Retrieved July 3, 2012, from http://rarediseases.info.nih.gov/GARD/Condition/8562/Seckel_syndrome.aspx
- Perez, E. (2012, February 28). Methymercury Poisoning. National Library of Medicine – National Health Institutes. Retrieved July 3, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/001651.htm
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