Spina Bifida - Risk factors and Etiology.

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Research Presentation
Spina bifida
Ken McIntyre
Montcalm Community College
Heather Wesp, Instructor

2. SSppiinnaa bbiiffiiddaa
Between the 15th and 28th day of pregnancy, the neural tube forms and
subsequently becomes the brain and spinal column. Normally, during this first
month of a pregnancy, the two sides of the spine join together to cover the spinal
cord, spinal nerves and (meninges) the tissues covering the spinal cord.
Spina bifida is a neural tube defect (NTD) that constitute a group of malformations
that result from failure of normal neural tube closure during the third and fourth
week of embryologic development. (American Society of Human Genetics)
Spina bifida refers to any birth defect involving incomplete closure of the spine.
Myelomeningocele is the most common type of spina bifida. It is a neural tube
defect in which the bones of the spine do not completely form, resulting in an
incomplete spinal canal. This causes the spinal cord and meninges (the tissues
covering the spinal cord) to stick out of the child's back. (PubMed Health)

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Image from: ultrasound-images.com

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Image from: University of Neurosurgery

5. Neural tube defects (NTDs) are a leading cause of infant mortality and morbidity involving
the central nervous system.
Spina bifida (SB) is a common NTD with the defect occurring in the developing spinal
cord resulting in various degrees of lower extremities paralysis. (American Society of
Human Genetics)
The 3 main types of Spina bifida include:
Occulta
Meningocele
Myelomeningocele

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Because Spina bifida refers to any birth
defect that involves the incomplete closure
of the spine, numbers indicating the rate of
occurrence vary.
On average Spina bifida occurs in 3 of
every 1,0000 births.
After a significant increase in the spina
bifida rate from 1992 to 1995, there was a
significant decline from 1995 to 1999.
(CDC)
Although declines were not significant
from 1999 to 2005, the rate for 2005,
17.96 per 100,000 live births, was the
lowest ever reported. (CDC)
Image: CDC

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Both environmental and genetic factors have been identified as
contributing to the cause of spina bifida.
Race.
Spina bifida is more common among whites and Hispanics. (Mayo Clinic)
Family history of neural tube defects.
Couples who've had one child with a neural tube defect have a slightly higher chance of
having another baby with the same defect. That risk increases if two previous children
have been affected by the condition. In addition, a woman who was born with a neural
tube defect, or who has a close relative with one, has a greater chance of giving birth to a
child with spina bifida. However, most babies with spina bifida are born to parents with no
known family history of the condition. (Mayo Clinic)

8. Folate deficiency.
Folate (vitamin B-9) is important to the healthy development of a fetus. Folate is the
natural form of vitamin B-9. The synthetic form, found in supplements and fortified foods,
is called folic acid. A folate deficiency increases the risk of spina bifida and other neural
tube defects. (Mayo Clinic)
Some medications.
Anti-seizure medications, such as valproic acid (Depakene), seem to cause neural tube
defects when taken during pregnancy, perhaps because they interfere with the body's
ability to use folate and folic acid. (Mayo Clinic)
Diabetes.
Women with diabetes who don't control their blood sugar well have a higher risk of
having a baby with spina bifida. (Mayo Clinic)

9. Obesity.
 Pre-pregnancy obesity is associated with an increased risk of neural tube birth defects,
including spina bifida. (Mayo Clinic)
Increased body temperature.
 Some evidence suggests that increased body temperature (hyperthermia) in the early
months of pregnancy may increase the risk of spina bifida. Elevating your core body
temperature by about 3 to 4 degrees Fahrenheit above normal — about 2 degrees
Celsius — due to fever or the use of saunas, hot tubs or tanning beds, has been
associated with increased risk of spina bifida. (Mayo Clinic)

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Symptoms
A newborn may have a sac sticking out of the mid to lower back. The doctor cannot
see through the sac when shining a light behind it.
Symptoms include:
 Loss of bladder or bowel control
 Partial or complete lack of sensation
 Partial or complete paralysis of the legs
 Weakness of the hips, legs, or feet of a newborn
Other symptoms may include:
 Abnormal feet or legs, such as clubfoot
 Build up of fluid inside the skull (hydrocephalus)
 Hair at the back part of the pelvis called the sacral area
 Dimpling of the sacral area
(PubMed Health)

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Signs
Prenatal screening can help diagnose this condition. During the second trimester,
pregnant women can have a blood test called the quadruple screen. This test screens
for myelomeningocele, Down syndrome, and other congenital diseases in the baby. Most
women carrying a baby with spina bifida will have a higher-than-normal levels of a
protein called maternal alpha fetoprotein (AFP).
If the quadruple screen test is positive, further testing is needed to confirm the diagnosis.
Such tests may include:
 Pregnancy ultrasound
 Amniocentesis
Myelomeningocele can be seen after the child is born. A neurologic examination may
show that the child has loss of nerve-related functions below the defect. For example,
watching how the infant responds to pinpricks at various locations may reveal where he
or she can feel the sensations.
(PubMed Health)

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If you're pregnant, prenatal screening tests to check for spina bifida and other birth
defects. The tests aren't perfect. Even if the results are negative, there's still a small
chance that spina bifida is present, and most mothers who have positive blood tests
have normal babies. (Mayo Clinic)
Blood Tests
The first line test used to check for spina bifida (myelomeningocele) is the maternal
serum alpha-fetoprotein (MSAFP) test. The blood is tested for alpha-fetoprotein
(AFP) — a protein that's produced by the fetus. It's normal for a small amount of
AFP to cross the placenta and enter the mother's bloodstream, but abnormally high
levels of AFP suggest that the fetus has a neural tube defect. (Mayo Clinic)
Ultrasound
Many obstetricians rely on ultrasonography to screen for spina bifida. The
information these images provide can help establish whether there's more than one
fetus and can help confirm gestational age — two factors that can affect AFP levels.
An advanced ultrasound can also detect signs of spina bifida, such as an open
spine or particular features in your baby's brain that indicate spina bifida. (Mayo
Clinic)

13. DDiiaaggnnoossiinngg SSppiinnaa bbiiffiiddaa
Amniocentesis
If a blood test shows high levels of AFP in your blood but the ultrasound is normal,
your doctor may offer amniocentesis. During amniocentesis, your doctor uses a
needle to remove a sample of fluid from the amniotic sac that surrounds the fetus. An
analysis indicates the level of AFP present in the amniotic fluid.
A small amount of AFP is normally found in amniotic fluid. However, when an open
neural tube defect is present, the amniotic fluid contains an elevated amount of AFP
because the skin surrounding the baby's spine is gone and AFP leaks into the
amniotic sac. (Mayo Clinic)

14. PPrrooggnnoossiiss
Spina bifida may cause no symptoms, or only minor physical disabilities, or it can
result in severe physical disabilities. More frequently, it leads to severe physical and
mental disabilities. Factors that affect the severity of complications include:
The size and location of the neural tube defect
Whether skin covers the affected area
Which spinal nerves come out of the affected area of the spinal cord
Treatments performed before and just after birth
Children with spina bifida can lead relatively active lives. The prognosis depends on
the number and severity of abnormalities and associated complications. Most children
with the disorder have normal intelligence and can walk, usually with assistive devices.
(NINDS)
Additional problems may arise as children with spina bifida get older. (Mayo Clinic)
My father didn't develop any complications until his mid 50's. And at almost 70 years
old, he is still active for his age.

15. HHoommeeoossttaassiiss
Most homeostatic mechanisms in the body is based on negative feedback. Homeostasis
is the body's way of maintaining certain set points that govern our bodies in order for
them to function efficiently, use their resources effectively, and to remain healthy and
viable.
The typical homeostatic mechanism involves 5 steps:
1. Stimulus – An external or internal change takes place;
2. Receptors – The body detects the external or internal change through certain sensory
receptors;
3. Control Center – The brain receives the information from the sensory receptors and
signals effectors;
4. Effectors – The body responds physically to correct the problem;
5. Response – The body returns to it's set point.

16. HHoommeeoossttaassiiss && SSppiinnaa bbiiffiiddaa
It appears that a glucose imbalance and deficiency of folate during pregnancy are
the two major risk factors for NTDs.
The results in a recent study strongly support a critical role of glucose homeostasis
maintaining genes as contributory to spina bifida susceptibility. Many of these genes
have been associated with diseases (including NTDs) due to diabetes or glucose
imbalance. The current findings support the hypothesis that maintenance of glucose
homeostasis during pregnancy as a vitally important for normal neural tube
development and implicate specific genes in this process. (American Society of
Human Genetics)
Spina bifida disrupts homeostasis early in the development of the fetus. Proper
development of the vertebral column and spinal canal is prevented, allowing internal
organs to be exposed and damaged.

17. Because Spina bifida occurs as early as the first 2 weeks of fetal
development, homeostasis is disrupted from the very beginning.
1. Stimulus – With Spina bifida, it appears the genes that determine the correct set
point of blood glucose levels fail, leading to a cascading set of failures in neural tube
development. The mutated genetic information in these genes may be a direct result
of little or no vitamin B-9 in the mother's diet.
2. Receptors – The receptors in the pancreas detect blood glucose levels and relay
that (incorrect) information to the control center (brain).
3. Control Center – When the brain does not receive the correct information from the
pancreas, it does not send the correct signal back to the pancreas. If the correct set
point is wrong or not known, the two hormones (insulin and glucagon) that are
responsible for controlling the concentration of glucose in the blood are not released
as needed.
4. Effector – In this case, the pancreas acts as both the primary receptor and effector.
5. Response – Again, in this case, the response is wrong and the body's “normal” set
point is not maintained.

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The effects begin at the genetic level.
At the chemical level, folic acid works along with vitamin B12 and vitamin C to help
the body break down, use, and create new proteins. This vitamin helps form red
blood cells and helps to produce DNA. (NLM) When folic acid (Vitamin B-9) is
lacking it can affect DNA synthesis and cell division.
The major effect on cells is they contain defective DNA, which result in an organ that
does not develop and can not function as it is required in order to keep the body
healthy.
Blood and bone are the major tissues effected. The blood contains more or less
glucose than the typical body's set point and the blood can deliver too little glucose
required for cellular respiration. Bone tissue is affected as it can not form properly.
The organs affected are:
• Skin. The skin fails to cover the spinal column which can allow foreign
material into the body. The skin also helps protect the spinal cord.

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The organs affected are:
• Bone. The vertebrae of the spinal column is the major means of
protection for the spinal cord. Not only does the vertebrae of the spinal
column form a harden, protective barrier around the spinal cord, it helps
to stabilize it from moving too much.
• Spinal Cord. Without the protection and stabilization of the vertebrae
and skin, the spinal cord protrudes from the body and is damaged and
subject to additional damage.
The organ system most affected is the Central Nervous System due to the damage
to the spinal cord. Without the protection of the spinal vertebrae and overlying
tissues, the spinal cord is damaged and unable to function properly.
The effect on the human body as a whole can be mild to fatal. In some cases,
people live full lives without any complications. In other cases, death occurs within
minutes of being born.

20. PPrreevveennttiioonn
Folic acid supplements may help reduce
the risk of neural tube defects such as
myelomeningocele. It is recommended that
any woman considering becoming
pregnant take 0.4 mg of folic acid a day.
Pregnant women need 1 mg per day.
It is important to remember that folic acid
deficiencies must be corrected before
becoming pregnant as the defects develop
very early.
Prospective mothers may be screened to
determine the amount of folic acid in their
blood. (PubMed Health)
The best way to reduce your risk? Watch
your weight, eat healthy and don't drink or
smoke.
Image from: http://www.childrenshealthyfood.com

21. Bibliography
American Society of Human Genetics. "Glucose Homeostasis Genes and Spina Bifida
Risk." Web. 17 Apr. 2011.
Centers for Disease Control and Prevention. (CDC) "CDC Data & Statistics | Feature:
Trends in Spina Bifida, United States, 1991 - 2005." Web. 17 Apr. 2011.
National Institute of Neurological Disorders and Stroke (NINDS). "Spina Bifida Fact
Sheet." Web. 18 Apr. 2011.
PubMed Health. "Myelomeningocele" Web. 17 Apr. 2011.
Spina Bifida Association "Mechanisms of Development (Pathogenesis)." Web. 17 Apr.
2011
Staff, Mayo Clinic. "Spina Bifida: Risk Factors - MayoClinic.com." Mayo Clinic. Web. 17
Apr. 2011.