What does it mean
to have a congenital brain defect?
Congenital brain defects are abnormalities in the brain that
are present at birth. There are many different types of these defects. They can
vary greatly from mild to severe conditions.
The brain begins to form in the first month after
conception, and will continue to form and develop throughout pregnancy. Development
of the brain begins from a small, special plate of cells on the surface of the
embryo. These cells grow and form the different regions of the brain.
When this process is disturbed or interrupted, it can cause
structural defects in the brain and skull. Normal brain function can be
impaired even if only the skull’s growth is upset.
Keep reading to learn more about congenital brain defects.
are the symptoms of congenital brain defects?
Symptoms of congenital brain defects vary. Each defect has a
distinct set of symptoms and impairments.
Some of these symptoms may not be apparent until after birth
when your child exhibits developmental or growth delays. Some congenital brain
defects don’t have symptoms until adulthood. Some never have symptoms at all.
Children born with congenital brain defects also may have:
- cardiovascular disorders
- gastrointestinal defects
- cleft lip and
- head pain
- muscle weakness
- reduced vision
- bladder and bowel problems
What are the types
of congenital brain defects?
Several types of congenital brain defects are caused by
neural tube defects.
Early in fetal development, a flat strip of tissue along the
back of the fetus rolls up to form the neural tube. This tube runs along most
of the length of the embryo.
The neural tube typically closes between the third and
fourth week after conception. It develops into the spinal cord with the brain
at the top. If the tube doesn’t close properly, the tissue within the tube
can’t develop properly. Neural tube defects that can occur as a result include:
Anencephaly: The head end of the neural
tube fails to close, and a major portion of the skull and brain is missing. The
missing portion of the skull means that brain tissue is exposed.
Encephalocele: A portion of the brain
bulges through an opening in the skull. The bulge is often located along the
front-to-back midline at the back of the skull.
Arnold-Chiari or Chiari II: Part of the cerebellum, a region of
the brain that affects motor control, is shifted downward into the upper spinal
column. This causes the brain or spinal cord to become compressed.
Other types of congenital brain defects develop within the
structure of the brain:
on the brain, this is an excessive buildup of cerebrospinal fluid (CSF) caused
by impaired circulation of the CSF. When there is excess fluid, it can put too
much pressure on the brain.
Dandy-Walker syndrome: This involves the
absence or defective growth of the central section of the cerebellum.
Holoprosencephaly: The brain doesn’t divide
into two halves, or hemispheres.
causes a person’s brain to be abnormally large or heavy.
occurs when the brain doesn’t develop to full size. The Zika
virus can cause microcephaly.
causes congenital brain defects?
Most congenital brain defects can’t be attributed to a
specific cause. A variety of genetic and environmental factors have been linked
to the development of congenital brain defects. These factors may be related to:
- gene defects
- drug use
- other trauma to an unborn fetus
Some brain defects are symptoms of trisomy.
Trisomy occurs when a third chromosome is present where typically there are only
Dandy-Walker syndrome and Chiari II defects are associated
with trisomy of chromosome 9. Trisomy of chromosome 13 can cause holoprosencephaly
and microcephaly. Symptoms of trisomy of chromosomes 13 and 18 can include
neural tube defects.
is at risk for congenital brain defects?
Some risk factors such as genetics are unavoidable. If you’re
pregnant or planning to become pregnant, there are some things you can do to
reduce the risk for congenital brain defects in your baby:
- Avoid alcohol, recreational drugs, and smoking.
Because a baby’s brain begins developing within the first month of conception,
it’s important to avoid these if you’re trying to become pregnant.
- Use of certain prescription drugs such as
(Coumadin), and retinoic acid may increase risk for brain defects. Talk to your
doctor about medications you’re taking if you’re trying to conceive or you’re
- Avoid exposure to X-rays or radiation therapy.
That includes X-rays at your dentist’s office. Always let your all of your
doctors know if you’re pregnant or may be pregnant.
- Nutritional deficiencies can affect your baby’s
brain, so maintain a healthy, balanced diet while pregnant. Doctors also
recommend taking a prenatal vitamin before you become pregnant and throughout
your entire pregnancy.
Infections such as rubella, herpes simplex, and varicella
zoster can also increase your baby’s risk for congenital brain defects.
While you can’t always avoid infections, there are things you can do to reduce
your risk for infection:
- Talk to your doctor about vaccines you should
get. They can recommend vaccines you may need before getting pregnant and ones
you should have once you have become pregnant.
- Avoid being around people who are sick when
possible. They may spread an infection to you.
- Avoid travelling to areas with known outbreaks.
That includes areas with mosquitos known to be carrying the Zika virus.
mellitus or phenylketonuria,
a rare genetic disease, during pregnancy also increases your risk for having a
baby with congenital brain defects.
Any type of trauma to the unborn child, such as falling on
your stomach while pregnant, also can affect brain development.
How are congenital brain defects diagnosed?
Your doctor may be able to identify a congenital brain
defect by detailed ultrasound. If
further investigation is needed, an MRI scan might be used to see details of
the brain and spine of the fetus.
It may be possible to identify a congenital brain defect as
part of a prenatal screening. This can be done by using chorionic
villus sampling (CVS) when you’re between 10 to 12 weeks pregnant. CVS is
used to identify various genetic conditions. Not all congenital brain defects
are genetic, so CVS will not always identify a congenital brain defect. Talk to
your doctor to learn more about CVS.
In some cases, accurate diagnosis may not be possible until
after birth when signs such as intellectual disabilities, delayed behavior, or seizures
may be more noticeable.
are congenital brain defects treated?
Treatment varies depending on the type and severity of the
condition. Many treatments will focus on treating the symptoms. For example, anticonvulsant
medications can help reduce episodes of seizures.
Some conditions can be treated with surgery. Decompression
surgery can create more space for brain and cerebrospinal fluid where needed.
Surgery to correct defective skulls can give the brain space to grow normally.
Shunts can be inserted to drain the cerebrospinal fluid that builds up with
is the outlook for congenital brain defects?
The effects of a congenital brain defect vary greatly. The
type and severity of the condition, the presence of other physical or mental impairments,
and environmental factors can contribute to the outlook.
Many congenital brain defects cause minor neurological
impairment. People with these types of congenital brain defects can grow to
function independently. Other defects are so severe that they are fatal before
or shortly after birth. Some cause significant disabilities. Others partially
disable people, limiting their mental functioning to a level that is below
there ways to prevent congenital brain defects?
Research and tracking of the incidence of birth defects has
helped medical experts identify specific ways to reduce congenital brain
for Disease Control and Prevention recommends that women who are pregnant
or considering pregnancy do the following:
- Take supplements containing 400 micrograms of
folic acid daily. Begin at least one month before getting pregnant. Taking
these supplements lowers the risk of having a baby with neural tube defects.
- Avoid drinking alcohol at any time.
- Quit smoking before getting pregnant or as early
as possible into your pregnancy.
- Keep blood sugar under control before and during
pregnancy, especially if you have diabetes.
- Talk to your healthcare provider before taking any
medications or herbal products during pregnancy. They can advise you on which
medications and supplements are safe during pregnancy.