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Spina bifida

Spina bifida describes birth defects caused by closure of one or more vertebral arches of the spine, resulting in malformations of the spinal cord. The spinal membranes and spinal cord may protrude through the absence of vertebral arches (called a cleft). These malformations range from spinal bifida occulta, spina bifida cystica (myelomeningocele) and meningocele.

The most common location of the malformations are in the lumbar[?] and sacral[?] areas. The lumbar nerves control the muscles in the hip, leg, knee and foot, and help to keep the body erect. The sacral nerves control some of the muscles in the feet, bowel and bladder and the ability to have an erection. Some degree of impairment can be expected in these areas.

Spina bifida is a Latin term meaning "split spine." Occulta means "hidden."

Table of contents

Spinal bifida occulta

This is a mild form of spina bifida. There is no opening on the back, but the outer part of some of the vertebrae are not completely closed. The split in the vertebrae is so small that the spinal cord does not protrude. The skin at the site of the lesion may be normal, or it may have some hairs growing from it; there may be a dimple in the skin, or a birthmark. People with this form may have incontinence, slight ambulatory problems, and slight loss of sensation.

Spina bifida cystica (myelomeningocele)

In this, the most serious form, the meningeal membranes that cover the spinal cord and part of the spinal cord protrude through a cleft, forming a sac or cyst, and are clearly visible. The opening is surgically repaired, shortly after birth. The sac or cyst not only contains tissue and cerebrospinal fluid but also nerves and part of the spinal cord. The spinal cord is damaged or not properly developed. As a result, there is always some degree of paralysis and loss of sensation below the damaged vertebrae. The amount of disability depends very much on where the spina bifida is and the amount of nerve damage involved. Many children and adults with this condition experience problems with bowel and bladder control. In approximately 90% of the people with myelomeningocele, hydrocephalus will also occur.

Meningocele

In this, the least common form, the outer part of some of the vertebrae are split and the meninges[?] are damaged and pushed out through the opening, appearing as a sac or cyst, which contains both the (meninges[?]) and cerebrospinal fluid. The nerves are not usually badly damaged and are able to function, therefore there is often little disability present. There are usually no long-term problems, although problems can arise.

Causes

Spina bifida is caused by the failure of the neural tube to close during embryonic development. Normally the closure of the neural tube occurs around the thirtieth day after fertilization. However, if something interferes and the tube fails to close properly, a neural tube defect will occur. Neural tube defects include, the conditions of anencephaly, encephalocele[?], and spina bifida.

Spina bifida occurs in the first month of pregnancy, often before the woman knows that she is pregnant.

Spina bifida does not follow direct patterns of heredity like muscular dystrophy or haemophilia.

It is known that women taking medication for epilepsy have a higher chance of having a child with a neural tube defect.

Effects

Spina bifida results in varying degrees of paralysis, absence of skin sensation, incontinence, and spine and limb problems depending on the severity and location of the lesion damage on the spine. In very rare case, cognitive problems also result.

Most babies born with the condition will need surgeries to correct spinal, foot or leg problems, shunt surgery to drain fluid from the brain, application of techniques to control bladder and bowel function (such as self-catherization[?]), and braces and other equipment to assist in walking.

Cures

There is no cure for spina bifida. To prevent further drying and damage of the nervous tissue and to prevent infection, doctors operate as soon as possible to close the opening on the back, but there is no operation that can fix damaged nerves. During the operation, the spinal cord and its nerve roots are put into place and covered with skin.

Rate

In the United States, spina bifida occurs in about one in every 1-2,000 births. More children in the U.S. have spina bifida than have muscular dystrophy, multiple sclerosis, and cystic fibrosis combined.

In Western Australia, up until 1996 around 2 children in every 1000 were born with a neural tube defect. Since 1996, as a result of the folic acid campaign, the figure has dropped to 1.3 children per 1000 births.

Prevention

Doctors and scientists have found that folic acid can help to prevent spina bifida. Folic acid must be taken for at least one month before conception and for the first three months of pregnancy. As yet it us unknown how or why folic acid helps to prevent spina bifida.



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