This is known by some people as 'hidden' spina bifida and is very common.
The split in the bone of the spine is small and the spinal cord and main nerves cannot bulge out, and more often than not little or no damage is done.
The only thing to see on the back may be a dimple, a tuft of hair, or a red mark.
Someone with spina bifida occulta may not have any problems at all, and probably wouldn't know they had this condition unless an x-ray of the back was taken.
Antenatal tests usually do not detect this type of spina bifida, before birth.
‘Occulta’ Means Hidden
Spina bifida occulta is not easily detected because skin covers the area, such as the spinal cord, spinal bone, or nerve roots, which may be affected. Spina bifida occulta can affect any level of the spine, but is usually found in the lower part of the back. This condition is a result of a spinal underdevelopment and is associated with disrupted development of the spinal nerve roots and spinal cord. The only thing to see on the back may be a dimple, tuft of hair, or a red mark.
The prevalence of occulta is not known, but it is probably the most common type of spina bifida. In the mid 1980s a study carried out in Great Britain suggested that 22% or 23% of people have spina bifida occulta.
Spina bifida occulta is usually discovered accidentally when the person has an x-ray or MRI for some other reason. It usually shows itself as just a small part of one vertebra low in the back which is missing.
See the diagrams below that show cross sections of one vertebra
Complications and Symptoms
Spina bifida occulta is rarely linked with complications or symptoms. Although there may be a slightly increased chance of a slipped disc; very few people with spina bifida occulta will ever have any problems because of it. If a person has no symptoms from spina bifida occulta as a child, then it is unlikely that they will have any as an adult.
Like most conditions, there are different severities of spina bifida occulta:
The most minor form will present as the plates of bone that form the spinal arch fail to fuse completely. This variation generally only affects one vertebra, particularly the vertebra lying lowest in the small of the back. Because there are no associated irregularities of the spinal cord or nerve roots, there are no leg, bladder or bowel problems.
However, for some people (about 2% of those who have spina bifida occulta) there can be other problems. These problems arise because there are other things involved around the area where the vertebra has not formed properly. For this small percentage of people the problem with the spine can also be more extensive than just a small piece of missing bone.
Spina Bifida Occulta Vs Occulta Spinal Dysraphism
When more than one vertebra is involved and these vertebrae have not developed fully spina bifida occulta can be referred to as occult spinal dysraphism (OSD). This may cause the person's back to be slightly short and often stiff. The natural curves of the back may be exaggerated and there may be an abnormal curvature of the spine or a bony protrusion in the midline of the back. There may be a bony peg at one level of the spinal canal, or a fibrous band running across it and dividing it into two. The spinal cord may become excessively wide because of abnormal fat or fibrous tissue lying inside the spinal canal. Leg, bladder, or bowel function may also be affected.
At Spina Bifida Hydrocephalus Ireland (SBHI) offers a number of supports to individuals, families, carers and professionals through our Family Support Services. Please click on the following link to the Family Support Page