Anencephaly is a condition present at birth that affects the formation of the brain and the skull bones that surround the head. Anencephaly results in only minimal development of the brain. Often, the brain lacks part or all of the cerebrum (the area of the brain that is responsible for thinking, vision, hearing, touch, and movement). There is no bony covering over the back of the head and there may also be missing bones around the front and sides of the head.
Anencephaly is a type of neural tube defect. Neural tube defects occur in about one of 1,000 pregnancies in the US each year.
During pregnancy, the human brain and spine begin as a flat plate of cells, which rolls into a tube, called the neural tube. If all or part of the neural tube fails to close, leaving an opening, this is known as an open neural tube defect, or ONTD. This opening may be left exposed (80 percent of the time), or covered with bone or skin (20 percent of the time).
Anencephaly and spina bifida are the most common ONTDs, while encephaloceles (where there is a protrusion of the brain or its coverings through the skull) are much rarer. Anencephaly occurs when the neural tube fails to close at the base of the skull, while spina bifida occurs when the neural tube fails to close somewhere along the spine.
ONTDs happen to couples without a prior family history of these defects in over 95 percent of the cases. ONTDs result from a combination of genes inherited from both parents, coupled with environmental factors. For this reason, ONTDs are considered multifactorial traits, meaning "many factors," both genetic and environmental, contribute to their occurrence.
Once a child has been born with an ONTD in the family, the chance for an ONTD to happen again is increased to 4 percent to 10 percent. It is important to understand that the type of neural tube defect can differ the second time. For example, one child could be born with anencephaly, while the second child could have spina bifida.
The following are the most common symptoms of anencephaly. However, each child may experience symptoms differently. Symptoms may include:
The symptoms of anencephaly may resemble other problems or medical conditions. Always consult your child's physician for a diagnosis.
The diagnosis of anencephaly may be made during pregnancy, or at birth by physical examination. The baby's head often appears flattened due to the abnormal brain development and missing bones of the skull.
Diagnostic tests performed during pregnancy to evaluate the baby for anencephaly include the following:
There is no cure or standard medical treatment for anencephaly. Treatment is supportive.
Experiencing the loss of a child can be very traumatic. Grief counseling services are available to help you cope with the loss of your child.
Genetic counseling may be recommended by the physician to discuss the risk of recurrence in a future pregnancy as well as vitamin therapy (a prescription for folic acid) that can decrease the recurrence for ONTDs. Extra folic acid, a B vitamin, if taken one to two months prior to conception and throughout the first trimester of pregnancy, has been found to decrease the reoccurrence of ONTDs, for couples who have had a previous child with an ONTD.