What's the difference between spinal bifida and spinal bifida occulta?

Type of spina bifida. The mildest form of spina bifida is spina bifida occulta and is a small separation or gap in one or more of the vertebral bones of the spine. Most people with spina bifida occulta have no signs or symptoms because their spinal nerves are undamaged. Signs sometimes occur in the skin on top of the spinal defect, such as a clump of hair, a dimple, a birthmark, or a lump of fat.