Is Spina Bifida Occulta Something to Worry About?
Usually, no. Spina bifida occulta is a small gap in one or more vertebrae at the base of the spine. It is extremely common. It affects up to one in ten people, and the vast majority never know they have it. Most people need no treatment at all. It is often found by chance on a scan or x-ray done for something else entirely.
Key points
- Spina bifida occulta means part of a vertebra did not fully close during development. The word "occulta" means hidden.
- It is usually an incidental spine finding. It is spotted on an x-ray or scan done for another reason.
- Most people have no symptoms and need no treatment.
- In rare cases, a related tethered spinal cord may need further tests.
- If you have new leg weakness, numbness, or bladder or bowel changes, get urgent medical help.
What is spina bifida occulta?
Spina bifida occulta is a minor variation in the way one or more vertebrae formed before birth. In a typical spine, each vertebra has a bony arch. This arch closes around the spinal cord to protect it. In spina bifida occulta, the arch did not fully close on one side. This leaves a small gap in the bone.
The word "occulta" comes from the Latin for hidden. The open forms of spina bifida are more serious. In this form, the spinal cord and nerves are not exposed. The skin over the area is intact. There is no visible opening, and most people live their whole lives without ever knowing about it.
The gap most often appears at the L5 or S1 level, right at the bottom of the spine. On an x-ray it shows up as an incomplete vertebral arch. Perhaps you recently had a full spine x-ray and saw this phrase on your report. If so, the information below will help you understand what it means.
Does spina bifida occulta cause symptoms?
In the vast majority of cases, no. Most people with spina bifida occulta have no symptoms at all. The gap in the bone is simply too small, and too well covered by the tissue around it, to cause any problems.
Some people worry that it is causing their back pain. In most cases, the two are not related. Back pain is extremely common. Seeing an incidental spine finding like this on your report does not mean it is the source of your discomfort.
Most people find out only when a scan or x-ray is done for another reason.
If you do have back pain, it is far more likely to have another cause.
A report often describes it as an "incidental finding" with no clinical significance.
What about a sacral dimple in adults?
A sacral dimple is a small dent in the skin at the very base of the spine, just above the crease of the buttocks. Many adults notice one and wonder if it is linked to spina bifida occulta.
Most sacral dimples are completely harmless and very common. They are simply a natural skin variation. Sometimes a dimple or other skin marker (such as a small tuft of hair or a patch of different-coloured skin) can sit over an area of spina bifida occulta. This does not mean anything is wrong.
If the dimple is shallow and close to the surface, it almost always needs no tests. A deeper dimple, or one with other skin changes, may sometimes lead your doctor to arrange further imaging to check the spinal cord underneath. This is uncommon.
Is spina bifida occulta serious?
For the overwhelming majority of people, it is not serious at all. It is one of the most common incidental findings on spine imaging. The spinal cord and nerves are not affected, and the skin is closed. So it behaves as a harmless variation in body structure, not a medical condition.
The name can cause needless alarm. Seeing "spina bifida" on a report naturally causes worry, because the open forms of spina bifida are serious conditions. But spina bifida occulta is a very different situation. It helps to think of it as a footnote on your report, not a diagnosis.
- No leg weakness or numbness
- Normal bladder and bowel function
- No foot changes that are getting worse
- Found by chance on a scan or x-ray
- New or worsening leg weakness
- Numbness spreading in the legs or feet
- Loss of bladder or bowel control
- Sudden severe back or leg pain
Important. If you develop sudden leg weakness, numbness in the saddle area, or any change in bladder or bowel control, contact your doctor or go to the nearest emergency department immediately. These are red-flag symptoms. They need urgent assessment, whatever your spine report already says.
When does spina bifida occulta need further tests?
Further tests are only needed in the rare case where the spinal cord may be tethered. A tethered cord means the bottom of the spinal cord is attached to the tissue around it more than it should be. This can stretch nerves as the body grows and moves. It is uncommon in adults with spina bifida occulta, but it does happen now and then.
Your doctor may suggest further tests if you have:
- Leg weakness that is getting worse, or changes in walking
- Gradual loss of feeling in the feet or legs
- Bladder problems with no other clear cause
- A foot that is slowly changing shape
If none of these apply to you, there is very little reason to have more imaging for spina bifida occulta on its own.
You may have ongoing spine or posture concerns beyond this incidental finding. If so, ScanAlign standing EOS imaging can capture your full spine while you stand, which shows how your body actually carries weight. This is a separate matter from spina bifida occulta itself.
If you are planning treatment for back or posture problems, or thinking of changing the treatment you are on, a detailed diagnosis first is worth it. Knowing whether the cause sits in the pelvis, the legs or the spine changes what will actually help.
Does spina bifida occulta show up on MRI or x-ray?
It is usually spotted on a plain x-ray as a gap in the bony arch of a vertebra. This is why it is so often called an incidental finding. The x-ray was taken for a different reason, and the gap simply shows up on the image.
When MRI is more helpful. EOS and x-rays show bones, joints and alignment clearly. But if a tethered cord or nerve involvement is suspected at all, MRI is usually the better tool. MRI shows soft tissue, the spinal cord and nerves in a detail that bone imaging cannot give. Your doctor will guide you on whether MRI is right in your case.
Frequently asked questions about spina bifida occulta
No. Spina bifida occulta is the mildest form. It is very different from the open forms (myelomeningocele or meningocele). In the open forms, the spinal cord or its coverings push through a gap in the spine. In occulta, the skin is closed and the cord is not exposed. Most doctors see it as a normal variation, not a disease.
Very common. Studies suggest it is present in up to one in ten people. Many never find out, because it causes no symptoms. It is only found if the lower spine happens to be imaged.
In the vast majority of cases, no. Back pain is extremely common and has many possible causes. If you have both spina bifida occulta and back pain, the two are almost always unrelated. Your treating specialist will look for more likely causes, such as muscle strain, disc problems or posture-related issues.
It means the bony arch of the fifth lumbar vertebra (L5), near the bottom of your spine, did not fully close. L5 and S1 are the most common places for this finding. On its own, it is seen as a normal variation in body structure and is not a cause for concern.
Almost never. It usually causes no symptoms, so there is nothing to treat. Treatment would only be considered in the rare case of a tethered spinal cord causing symptoms that get worse. A specialist would make that decision.
A shallow sacral dimple near the skin surface is very common and harmless. If it is deeper, sits further from the crease, or comes with other skin changes like a tuft of hair, your doctor may suggest further assessment. This is uncommon.
The gap in the bone itself does not change. It has been there since before birth. In very rare cases where a tethered cord is present, symptoms can slowly get worse. But this is the exception, not the rule.
If you have no symptoms, you do not need a follow-up scan for this finding alone. If you have separate concerns about your spinal alignment or posture, you could discuss a standing spine assessment with your treating specialist, or book a standing spine scan to look at your overall alignment.
There is some evidence that it can run in families, but the genetics are not simple. It is shaped by a mix of genetic and environmental factors during early development. Having it yourself does not necessarily mean your family members will have it.
An incidental finding is something spotted on a scan or x-ray that was not the reason you had it done. It is an observation, not necessarily a problem. A diagnosis is a confirmed condition that explains your symptoms or needs managing. Spina bifida occulta almost always falls into the "incidental finding" group.
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- NHS. Spina bifida: overview. nhs.uk (accessed 2024).
- Defined by Fidas A et al. "Prevalence of spina bifida occulta in a clinically normal population." Clinical Radiology, 1987; 36(2): 159-160.
- American Association of Neurological Surgeons. Spina Bifida. aans.org (accessed 2024).
Written by Abbas Dhami (Specialist Diagnostic Radiographer)
This page is general information and not a diagnosis.
ScanAlign is the trading name of CoreMed Solutions Ltd and operates under The Harley Street Hospital's CQC licence.