"Occulta" means hidden. The mildest form, spina bifida occulta results in a small separation or gap in one or more of the bones of the spine (vertebrae).
Many people who have spina bifida occulta don't even know it, unless the condition is discovered during an imaging test done for unrelated reasons.
In a form of spina bifida called meningocele, the protective membranes around the spinal cord (meninges) push out through the opening in the vertebrae, forming a sac filled with fluid.
But this sac doesn't include the spinal cord, so nerve damage is less likely, though later complications are possible.
Also known as open spina bifida, is the most severe form. The spinal canal is open along several vertebrae in the lower or middle back.
The membranes and spinal nerves push through this opening at birth, forming a sac on the baby's back, typically exposing tissues and nerves. This makes the baby prone to life-threatening infections.