Anencephaly is a condition that is present at birth (birth defect). It affects the brain and skull bones. With this condition, the brain is not fully formed. It often lacks part or all of the cerebrum. The cerebrum is the area of the brain used for thinking, seeing, hearing, touch, and movement. There is also no bone on the back of the head. Bones may also be missing on the front and sides of the head. Anencephaly is a type of neural tube defect. It occurs in about 3 of 10,000 pregnancies in the U.S. each year. The exact number is not known because many of these pregnancies end in miscarriages. This condition most often leads to death in days or weeks.
During pregnancy, the brain and spine begin as a flat plate of cells. This plate rolls into a tube called the neural tube. The tube is completely formed 28 to 32 days after conception. If all or part of the neural tube fails to close, this leaves an opening. The opening is called an open neural tube defect. The opening in the tube may be left exposed. Or it may be covered with bone or skin. Anencephaly is when the neural tube fails to close at the base of the skull.
Neural tube defects may be caused by genes passed on from both parents and by environmental factors. Some of these factors include obesity, uncontrolled diabetes in the mother, and some prescription medicines. In most cases, a child with a neural tube defect has no family history of this problem.
Once a child with a neural tube defect has been born in the family, the chance that this problem will happen in another child rises to 1 in 25. The type of neural tube defect can differ the second time. For example, one baby could be born with anencephaly. A second baby could have spina bifida instead.
Symptoms can occur a bit differently in each child. They can include:
The diagnosis of anencephaly may be made during pregnancy. Tests done during pregnancy to check for anencephaly include:
After birth, a diagnosis is made by physical exam. The baby's head often appears flattened because of the abnormal brain growth and missing bones of the skull.
There is no cure or standard treatment for anencephaly. Treatment is supportive. This means efforts are made to keep the baby as comfortable as possible. Anencephaly most often leads to death in days or weeks. Grief counseling services are available to help parents cope with the loss of their child.
The neural tube closes 28 to 32 days after a baby is conceived. This is before many women are aware that they are pregnant. Normal brain and spinal cord development may be affected during these first 3 to 8 weeks of pregnancy by:
Researchers have found that a woman who gets enough folic acid (vitamin B-9) can help lower the risk for neural tube defects. Folic acid is found in some leafy green vegetables, nuts, beans, citrus fruits, and fortified breakfast cereals. It is recommended that all women of childbearing age take a multivitamin that has folic acid. Folic acid is in prenatal vitamins. Getting this vitamin before a woman knows she is pregnant and early in pregnancy is most important.
If you have had a child with a neural tube defect, your healthcare provider may recommend taking a larger amount of folic acid before your next pregnancy. Your provider may tell you to take this extra amount for 1 to 2 months before conception and then through the first trimester.
Your healthcare provider may also advise genetic counseling. You can discuss with a counselor the risk for a neural tube defect in a future pregnancy. Also talk with your provider about getting a prescription for folic acid to lower the risk for another open neural tube defect.
Call the healthcare provider if your child has:
Tips to help you get the most from a visit to your child’s healthcare provider:
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