Spina Bifida Occulta

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Spina Bifida Occulta
A mild form of Spina Bifida

What is Spina Bifida Occulta?
Spina Bifida Occulta (SBO) is a group of conditions affecting the spinal column. The spinal column is made of bones, called “vertebrae.” They support the body and protect a large group of nerves, called the “spinal cord.” The spinal cord carries nerve signals from the body to the brain.
SBO is common; 10 to 20 percent of healthy people have it. Normally it is safe and people often find out they have it through an X-ray. Spina Bifida Occulta usually doesn’t cause nervous system problems.

Forms of Occulta
There are forms of Spina Bifida Occulta that do cause problems though. They are:

  • Lipomyelomeningocele and lipomeningocele — this is like a tethered spinal cord, except it is attached to a benign fatty tumor;
  • Thickened filum terminale — the end of the spinal cord is too thick;
  • Fatty filum terminale — there is a fatty lump at the inside end of the spinal cord;
  • Diastematomyelia (split spinal cord) and diplomyelia — the spinal cord is split in two, usually by a piece of bone or cartilage; and
  • Dermal sinus tract (with involvement of the spinal cord) — the spinal canal and the skin of the back are connected by what looks like a band of tissue.

Signs of Occulta
People can have these forms of Spina Bifida Occulta even if there is nothing wrong with the spine. However, there can be neurological complications associated with SBO. The most frequently occuring complication is a tethered spinal cord. A tethered cord occurs when the spinal cord (usually at the lower end) is not attached correctly to the rest of the body. The cord gets stretched and damaged.

The signs and symptoms of a possible neurological complication like a tethered spinal cord include:

  • Pain in the back or legs;
  • Weakness in the legs;
  • numbness or other changes in feeling in the legs or back;
  • Deformed legs, feet and back; and
  • Change in bladder or bowel function.

People who could have a spinal cord problem should see a health care provider right away.

What about people with no signs of a problem?
Eighty percent of those with a spinal cord problem will have skin over the defect with:

  • a hairy patch;
  • a fatty lump;
  • a hemangioma — a red or purple spot made up of blood vessels;
  • a dark spot or a birth mark — these are red and don’t include blue-black marks, called “Mongolian spots”;
  • a skin tract (tunnel) or sinus — this can look like a deep dimple, especially if it’s too high (higher than the top of the buttocks crease), or if its bottom can’t be seen; and
  • a hypopigmented spot — an area with less skin color.

No matter the age, people who have these signs should see a health care provider who treats the spinal cord. Not every person with a skin defect of the lower back has Spina Bifida Occulta however, but that can only be determined through physical examination and diagnostic tests. This is especially true for those with sacral dimple. An ultrasound (only for newborns) or magnetic resonance imaging (MRI) may be used to confirm a problem.

This information does not constitute medical advice for any individual. As specific cases may vary from the general information presented here, SBA advises readers to consult a qualified medical or other professional on an individual basis.

Contributing Editor
Stephen Kinsman, MD