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Spina Bifida

Introduction

A group of disabilities classified as ‘neural tube defects’ is characterized by congenital malformations of the central nervous system. The most common of these disabilities are spina bifida and anencephaly. Spina bifida occurs when the spinal region fails to develop properly in the first 5 days of pregnancy. The fault can occur at any level of the spine but is most common at about waist level. In general, spina bifida is the most common disability apparent at birth.

Main Characteristics

i- Spina bifida occulta is a fairly common from but rarely causes disability. It generally occurs at the sacral region and is usually only detectable by X-ray. In this type the skin is intact and usually the only exterior signs of spina bifida are a dimple o tuft of hair on the back. In most instances the nervous system is not affected, but in rare cases there is paralysis.

ii- Spina bifida cystic can be divided into two types:

    a- Meningocele, the less common of two, show as a sac or cyst on the back, rather like a large blister, covered by a thin layer of skin. The sac is composed of the meaning [membranes covering the spinal cord] which protrude through the bifid [split] vertebrae. Neurological abnormalities do not usually occur with meningocele, as the spinal cord itself and its roots and not disturbed.

    b- Myelomeningocele is the more common and more sever form. The sac or cyst contains not only tissue and cerebrospinal fluid but also nerves and part of the spinal cord itself, which is usually deformed and open n the surface. Although the commonest site is the lumbar region, the lesion can occur at any point on the spine. As a result there is always some degree of flaccid paralysis [floppiness] below the damaged vertebrae. All cases of myelomeningocele involve the spinal cord. As a result, the legs may be severely paralyzed and congenital dislocation of the hip is common. As well as paralysis, many children have poor blood circulation and loss of skin sensation to pain, temperature, and touch. Burns and pressure sores can result without them being aware of it. When sitting or lying for long periods, it is important to change the position regularly to avoid undue pressure.

    c- Anencephaly In this condition, the brain does not develop properly and the baby is stillborn or dies shortly after birth.

 

More than 80 percent of babies born with spina bifida also have a condition called hydrocephalus [commonly known as ‘water on the brain’], although this can occur quite independently. The condition is due to an abnormal accumulation of the cerebrospinal fluid under pressure and, if untreated, can cause eventual brain damage and death. Congenital hydrocephalus is due mainly to malfunctions of the brain causing blockage to the flow of fluids and separation of the joints of the skull, resulting in enlargement of the skull. Acquired hydrocephalus may occur at any age as a result of head injuries, cerebral hemorrhage, or meningitis.