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. Children born to mothers taking certain medicines are at risk of anencephaly. It is important to talk with your healthcare provider about the safety of your medicines when pregnant. Don't stop or change your medicines without first talking with your healthcare provider.
Symptoms can occur a bit differently in each child. They can include:
No bones on the back of the head
Missing bones on the front and sides of the head
Large areas of brain missing
Folding of the ears
Split in the roof of the mouth (cleft palate)
Congenital heart defects
The symptoms of anencephaly can be like other health conditions.
The diagnosis of anencephaly may be made during pregnancy. Tests done during pregnancy to check for anencephaly include:
Blood test. A test called a quad screen measures 4 substances in the mother's blood to see if there is an increased risk for neural tube defects and other problems. This test is done between 16 and 18 weeks of pregnancy. It measures levels of alpha-fetoprotein (AFP) and other things in the blood. AFP is a protein made by the baby growing in the womb. If a baby has an open neural tube defect, the AFP level in the mother's blood will be higher than normal. The test isn’t conclusive. But it can show if your baby is at risk for an open neural tube defect. The test can show if you need more testing. It is advised that this blood test be offered to all pregnant women.
Prenatal ultrasound. This imaging test uses high-frequency sound waves and a computer to make images of blood vessels, tissues, and organs. Ultrasounds let healthcare providers see the internal organs as they function. They also show blood flow through blood vessels. Prenatal ultrasound may be able to find an open neural tube defect. Your provider may also use ultrasound to look at other organs and body systems of the baby.
Amniocentesis. This test looks at a small sample of the fluid that surrounds the baby in the womb. The healthcare provider uses a long, thin needle to reach the amniotic sac. He or she takes the sample of fluid and checks it for AFP. The test may not be able to find small or closed defects.
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:
Not enough vitamins such as folic acid and other nutrients
Using prescription medicine or alcohol
Being around hazardous chemicals and other substances
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:
Symptoms that don’t get better, or get worse
Anencephaly is a condition that is present at birth (birth defect). It affects the brain and skull bones. The brain is not fully formed. 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 most often leads to death in days or weeks.
Anencephaly is a type of neural tube defect. Neural tube defects are caused by genes passed on from both parents and by environmental factors.
You may need tests while you are pregnant to check for anencephaly in your growing baby.
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 healthcare provider may also advise genetic counseling. You can discuss with a counselor the risk for a neural tube defect in a future pregnancy.
Tips to help you get the most from a visit to your child’s healthcare provider:
Know the reason for the visit and what you want to happen.
Before your visit, write down questions you want answered.
At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.
Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
Ask if your child’s condition can be treated in other ways.
Know why a test or procedure is recommended and what the results could mean.
Know what to expect if your child does not take the medicine or have the test or procedure.
If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.