Anencephaly symptoms include a missing or incomplete brain, skull and scalp. These areas are important for thinking, hearing, vision, emotion and coordinating movement.
Anencephaly occurs when the upper part of the neural tube fails to close completely during fetal development. This causes the baby’s brain and skull to develop outside of normal boundaries (ectodermal growth).
The neural tube is a long, thin piece of tissue that grows into a tube, like a piece of string, and helps form the brain, spinal cord and bones. The tube also forms blood vessels that supply the fetus with nutrients.
When the upper part of the neural tube doesn’t close, the brain and spine are exposed to the amniotic fluid that surrounds the fetus in the womb. This exposure causes the nerves to break down and become degenerated.
Most babies with anencephaly die before birth or within a few hours or days after their birth. They may be blind, deaf and cannot sustain their own life.
Women can reduce their risk of conceiving a baby with anencephaly by getting enough folic acid, which is the form of vitamin B9. Folate is found in some foods, especially spinach, dark leafy greens and broccoli, but is also available as a supplement.
Fetal screening tests, such as the maternal serum alpha-fetoprotein test and detailed fetal ultrasound, can detect anencephaly and other neural tube defects. If these screening tests are positive, doctors usually perform amniocentesis, a procedure that withdraws fluid from the fetus’s amniotic sac and tests it for several markers of abnormal development.
Screening for Anencephaly During Pregnancy
During pregnancy, many of the symptoms of anencephaly are easy to notice. A pregnant woman will often feel sick to her stomach and bloated (dysphoric). The skin may be swollen, red and tingly, and the baby may look small.
Doctors will check the height and weight of the fetus during an ultrasound scan. They will also check the fetus’s head size by looking at its scalp.
A fetal sonogram can show signs of anencephaly, such as an open skull, missing parts of the scalp and a mass of spongy tissue floating above or to the side of the head. This spongy material is called an angiomatous stroma.
An MRI scan can also be used to examine the brain of an infant with anencephaly. It can be done at different times in a child’s life to check for any changes.
The MRI can help determine the exact extent of the problem and may indicate other conditions that may need treatment, such as a brain tumor or stroke. The MRI may also be used to see the baby’s chromosomes, which can help pinpoint the cause of anencephaly.
Anencephaly can be caused by a number of factors, including a change in the fetus’s genes or chromosomes. It also may be inherited (passed down through families). The risk of having a baby with anencephaly is higher for women who have already had a baby with a neural tube defect, such as spina bifida.
