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Spina Bifida
The most common physically disabling birth defect in Canada, Spina
Bifida affects one out of every 750 children born. It is classified as a neural
tube defect (NTD) and occurs during the first four weeks of pregnancy.
Spina Bifida is the incomplete development of the nervous
system and spinal cord, and results in varying degrees of permanent paralysis,
loss of sensation, and bladder and bowel dysfunction. In some cases, it can also
limit hand function, vision, hearing and learning abilities.
The most common types of Spina Bifida are:
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Myelomeningocele (or meningomyelocele) is the severest
and most common form of spina bifida in which the spinal cord and the meninges
(covering of the spinal cord) protrude from an opening in the spine to form a
sac (cele). Because the spinal cord leaves the protective bone tube of the
spine, damage to the nerves occurs. Urgent treatment is necessary at birth to
minimize further neurological damage and infection. Below the opening is where
nerve damage can affect development of muscles and limbs. Bowel and bladder
function are also frequently affected. In some cases, the skin covering will be
absent, requiring surgical closure. |
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Meningocele is considered a less severe and rarer form of
spina bifida. The meninges are pushed out through an opening in the spine to
form a sac containing cerebrospinal fluid (CSF), which is often covered by skin.
However the spinal cord does not leave the protective bone tube: because the
nerves remain protected, they are usually not as severely affected. The person
with this form of spina bifida usually has better physical development and bowel
and bladder control than one with myelomeningocele. |
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| Lipomyelomeningocele is an abnormal fat accumulation that
starts below the skin and extends through an opening in the spine to the spinal
cord. The skin covered lesion created is found in the buttock or lower spine
area, and is usually not painful. Symptoms, such as muscle weakness or loss of
sensation in the lower legs and feet, and bowel or bladder incontinence, occur
due to compression of the nerves by the fatty mass (during periods of rapid
weight gain) or the attachment of the fat to the spinal cord. Surgery may be
required to release the tethering of the spinal cord to the fatty mass
(especially during growth spurts) and to reduce the bulk of the fatty tumour. |
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Occulta, which means "hidden", is the
mildest form of spina bifida. A defect exists where one or more vertebrae are
not properly closed, but there is no protruding sac or protrusion of the spinal
cord. The results of this form of spina bifida may include a sensitive
depression (dimple) somewhere along the spine which often has long, dark hairs
sticking out of it. Many people have this condition and only become aware of it
when they have unexplained incontinence, back ache, or changes in the muscles of
their legs. Also, bed wetting may be a problem due to ‘cord tethering’. |
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Download
SBHAC fact sheet on Spina Bifida Occulta |
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People born with spina bifida frequently also have
hydrocephalus, however an individual may have hydrocephalus without having spina
bifida. Hydrocephalus is a condition in which normal cerebrospinal fluid (CSF)
circulation patterns are interrupted. The two most common causes of this are
accidents and birth defects, however hydrocephalus can also occur as a result of
brain tumours, cysts, scarring, infection, drug reactions and as a part of the
aging process.
Approximately 500 mL of CSF is produced daily within the
cavities of the brain that are called ventricles. Normally this CSF circulates
freely in and around the brain and spinal cord and is reabsorbed from the
tissues around the brain into the bloodstream. When the circulatory pathway is
blocked, CSF collects in the ventricles causing them to enlarge, which applies
increasing pressure on the brain tissue. This excess pressure may result in
various symptoms including dizziness, vomiting, severe pain and blurred vision.
If left untreated, the pressure on the brain tissue causes the skull to enlarge.
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| There is no cure for hydrocephalus, however it can be controlled by the
surgical insertion of a shunt (a long, flexible tube with a one way valve). A
shunt channels the flow of fluid away from the brain or spinal cord into another
part of the body, where the CSF can be carried away into the bloodstream. For a more complete definition of spina bifida or hydrocephalus, please visit
the Spina Bifida and
Hydrocephalus Association of Canada's web site.
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