Spina Bifida Occulta
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Spina= Latin: “spine”
Bifida= Latin: “split”
Occulta = Latin: “hidden.” (Unlike in “open” spina bifida, the defect in spina bifida occulta is not visible.)
Spina bifida occulta is a malformation of one or more vertebrae (bones of the spine). It is sometimes called “closed” spina bifida. In most cases, spina bifida occulta causes no problems.
The general term spina bifida describes several conditions that all arise from a defect in an embryo’s developing spine. Many people are familiar with the most severe type of spina bifida, sometimes called “open” spina bifida. Open spina bifida may cause severe symptoms.
Fewer people are familiar with spina bifida occulta, or “closed” spina bifida. Closed spina bifida usually causes no symptoms at all. People may only discover they have the condition after they receive an X-ray or magnetic resonance (MR) imaging scan for a separate problem. The National Institute of Neurological Disorders and Stroke estimates that 10- 20 percent of people may have spina bifida occulta.
Occasionally, spina bifida occulta does cause symptoms. This usually occurs when the defect is more extensive—for example, if it involves more than one bone.
Most cases of spina bifida occulta cause no symptoms and need no treatment. However, a small number of people with more extensive spina bifida occulta may have some of the following symptoms:
- Foot deformity
- Leg weakness, numbness, or clumsiness
- Bladder or bowel dysfunction
- Hand weakness or numbness
These symptoms can be the result of a tethered cord. Left untreated, tethered cord can cause progressive damage to the spinal cord.
Sometimes, spina bifida occulta is indicated by a visible sign on the skin directly over the defect. Examples include a patch of thick hair, a growth, an unusual pigment, an extremely large dimple, or a pad of fat.
Otherwise, spina bifida occulta is usually an incidental finding, or condition found when examining a patient for a separate reason. X-rays, which use invisible electromagnetic energy to project images of the body’s structures onto film, can reveal the structural malformation of spina bifida occulta.
If neurological symptoms like those associated with tethered cord are present, a magnetic resonance (MR) imaging scan may be ordered. MR scans use radio waves and a magnet to produce images of organs and other tissues. They are especially useful for examining the spinal cord.
The exact causes of spina bifida occulta are not well understood. Both genetic and environmental factors seem to play a role.
In general, a family history of spina bifida is a risk factor for having a child with spina bifida. However, this may not hold true for mild spina bifida occulta: people with mild spina bifida occulta may not have a family history of the condition, and they do not appear to have a greater than average risk of having a child with spina bifida.
Even so, a woman who knows she has spina bifida occulta may wish to speak with her doctor if it is possible for her to become pregnant. She may wish to minimize environmental risk factors for spina bifida in any pregnancy, whether planned or unplanned.
Environmental risk factors for spina bifida include maternal folate deficiency very early in pregnancy, maternal health conditions like diabetes or obesity, and maternal use of certain medications early in pregnancy.
When spina bifida occulta causes no symptoms, it requires no treatment.
When it causes tethered cord, surgery to release the tether is sometimes recommended.
In general, for any type of tether surgery, the bones of the spinal column are opened from behind to expose the full extent of the spinal cord tethering. Our doctors often work collaboratively with neurophysiologists to monitor spinal cord and nerve function during the delicate operations. This careful monitoring can help minimize risk to the spinal cord, nerves, and nerve roots.
The great majority of patients do well with surgery. Most stabilize or even improve their level of function. The spinal cord does have the potential to re-tether after surgery, though. For this reason, follow-up care is important after tethered cord surgery.