What is anencephaly?
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.
What causes anencephaly?
Anencephaly is a type of neural tube defect that occurs in about 3 of 10,000 pregnancies in
the U.S. each year. The actual number is unknown because many of these pregnancies
end in miscarriages.
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 or covered with bone or skin.
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 the vast
majority of cases. ONTDs result from a combination of genes inherited from both parents,
coupled with environmental factors.
Once a child has been born with an ONTD in the family, the chance for an ONTD to happen
again is increased by 4% to 10%. 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.
What are the symptoms of anencephaly?
The following are the most common symptoms of anencephaly:
Absence of bony covering over the back of the head
Missing bones around the front and sides of the head
Folding of the ears
Cleft palate. A condition in which the roof of the child's mouth does not completely
close, leaving an opening that can extend into the nasal cavity.
Congenital heart defects
Some basic reflexes, but without the cerebrum, there can be no consciousness and the
baby can't survive
The symptoms of anencephaly may look like other problems or medical conditions.
How is anencephaly diagnosed?
The diagnosis of anencephaly may be made during pregnancy, or at birth by physical
exam. The baby's head often appears flattened due to the abnormal brain development
and missing bones of the skull.
Tests done during pregnancy to evaluate the baby for anencephaly include the following:
Alpha-fetoprotein. A protein produced by the fetus that is excreted into the amniotic
fluid. Abnormal levels of alpha-fetoprotein may indicate brain or spinal cord defects,
multiple fetuses, a miscalculated due date, or chromosomal disorders.
Amniocentesis. A test done to determine chromosomal and genetic disorders and certain
birth defects. The test involves inserting a needle through the abdominal and uterine
wall into the amniotic sac to retrieve a sample of amniotic fluid.
Ultrasound (also called sonography). A diagnostic imaging technique that uses high-frequency
sound waves and a computer to create images of blood vessels, tissues, and organs.
Ultrasounds are used to view internal organs as they function, and to assess blood
flow through various vessels.
Blood tests. A quad screen measures 4 substances in the mother's blood to determine
if there is an increased risk of having neural tube defects.
Treatment of the newborn with anencephaly
There is no cure or standard medical treatment for anencephaly. Treatment is supportive.
This means efforts are made to keep the baby as comfortable as possible.
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 doctor 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 1 to
2 months before 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. The CDC also recommends avoiding smoking and drinking alcohol during