Spina Bifida Occulta
Spina bifida occulta is the mildest form of spina bifida. When someone has this condition, at least one vertebra is malformed, but the nerves and spinal cord are normal and are covered by a layer of skin. Although it is estimated that 5 to 10 percent of the population has this condition, some cases may never be detected.
What Is Spina Bifida Occulta?
Spina bifida is a medical condition that 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 4 million babies born each year.
Spina bifida occulta is the mildest form of spina bifida and is often called hidden spina bifida. In spina bifida occulta, at least one vertebra is malformed, but the nerves and spinal cord are normal and are covered by a layer of skin. Approximately 5 to 10 percent of the population is believed to have spina bifida occulta.
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, the result can be brain disorders called neural tube defects. Spina bifida is a type of neural tube defect that is caused by the failure of the fetus's spine to close properly during the first month of pregnancy.
What Causes Spina Bifida Occulta?
The exact cause of spina bifida occulta is not known. However, research scientists suspect that the cause of this disorder could be genetic, or that nutritional and environmental factors could also play a role.
(Click Causes of Spina Bifida for more information.)