What Is Spina Bifida?
Spina bifida, which literally means "cleft spine," is characterized by the incomplete development of the brain, spinal cord, and/or meninges (the protective covering around the brain and spinal cord). It is the most common neural tube defect in the United States, affecting 1,500 to 2,000 of the more than four million babies born each year.
Understanding the Neural Tube
The human nervous system develops from a small, specialized plate of cells along the back of an embryo. Early in development, the edges of this plate begin to curl up toward each other, creating the neural tube, which is a narrow sheath that closes to form the brain and spinal cord of the embryo. As development progresses, the top of the tube becomes the brain and the remainder of the tube becomes the spinal cord. This process is usually complete by the 28th day of pregnancy. However, if problems occur during this process, they can result in brain disorders called neural tube defects. Spina bifida is a neural tube defect that is caused by the failure of the fetus's spine to close properly during the first month of pregnancy.
The three most common types of spina bifida are:
- Myelomeningocele, the most severe form, in which the spinal cord and its protective covering (the meninges) protrude from an opening in the spine (see Myelomeningocele)
- Meningocele, in which the spinal cord develops normally but the meninges protrude from a spinal opening (see Meningocele)
- Spina bifida occulta, the mildest form, in which one or more vertebrae are malformed and are covered by a layer of skin (see Spina Bifida Occulta).
Spina bifida may also cause bowel and bladder complications, and many children with spina bifida will have
hydrocephalus, which is an excessive accumulation of cerebrospinal fluid in the brain.
The exact cause of spina bifida is not known. However, research scientists suspect that there may be a genetic cause or that nutritional and environmental factors may play a role in the development of the condition.
(Click Causes of Spina Bifida for more information about the possible causes of spina bifida, including risk factors.)
The symptoms of this condition vary from person to person, depending on the type of spina bifida. In most cases, people with
spina bifida occulta (the mildest type) have no outward symptoms. In the most severe cases of spina bifida, infants will be born with an open lesion on their spine where significant damage to the nerves and spinal cord has occurred. Although the spinal opening can be surgically repaired shortly after birth, the nerve damage is permanent, resulting in varying degrees of paralysis of the lower limbs.
Other symptoms of spina bifida include:
- Improperly formed or missing vertebrae and accompanying nerve damage
- Physical and mobility difficulties
- Learning disabilities.
In most cases, a spina bifida diagnosis is made before birth. However, mild cases may go unnoticed until after birth. Very mild cases, in which there are no symptoms, may never be detected.
(Click Spina Bifida Diagnosis for more information.)
Tests that are used to make a spina bifida diagnosis include:
- Second-trimester maternal serum alpha-fetoprotein screening
- Fetal ultrasound
- Multiple-marker screens
- Amniocentesis.
Although there is no
cure for spina bifida, treatment may include surgery, medication, and physiotherapy.
Treatment options include:
- Assistive devices such as braces, crutches, or wheelchairs.
- Ongoing therapy, medical care, and surgical treatments -- these may be necessary to prevent and manage complications throughout the individual's life.
- Surgery to close the newborn's spinal opening. Surgery is generally performed within 24 hours after birth to minimize the risk of infection and to preserve existing function in the spinal cord.
Prognosis
The prognosis for individuals with spina bifida will depend on the number and severity of abnormalities. The prognosis is poor for those with complete paralysis,
hydrocephalus, and other congenital defects. However, with proper care, most children with spina bifida live well into adulthood.
Can Spina Bifida Be Prevented?
Recent studies have shown that
folic acid may significantly reduce the incidence of spina bifida. Therefore, it is recommended that all women of childbearing age consume 0.4 mg of folic acid daily.
