Spina bifida literally means “cleft spine.” It is characterized by the incomplete development of the brain, spinal cord, and/or meninges (the protective covering around the brain and spinal cord).
Physiological Background
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 — a narrow sheath that usually closes to form the brain and spinal cord of the embryo. The top of the tube becomes the brain and the remainder becomes the spinal cord. This process is usually complete by the 28th day of pregnancy.
But if problems occur during this process, the result can be brain disorders called neural tube defects. Spina bifida is one of these disorders.
It is the most common neural tube defect in the United States—affecting 1,500 to 2,000 of the more than 4 million babies born in the country each year.
Types of Spina Bifida
There are four types of spina bifida: occulta, closed neural tube defects, meningocele, and myelomeningocele.
- Occulta is the mildest and most common form in which one or more vertebrae are malformed. This form of spina bifida rarely causes disability or symptoms.
- Closed neural tube defects make up the second type of spina bifida, marked by a malformation of fat, bone, or membranes. Disability ranges from few or no symptoms to incomplete paralysis with urinary and bowel dysfunction.
- In the third type, meningocele, the meninges protrude from the spinal opening, and the malformation may or may not be covered by a layer of skin. The range of disability is similar to closed neural tube defects.
- Myelomeningocele, the fourth form, is the most severe and occurs when the spinal cord is exposed through the opening in the spine, resulting in partial or complete paralysis of the parts of the body below the spinal opening.
del.icio.us
Digg this
