There are three main types of spina bifida: occulta, meningocele and myelomeningocele. Occulta has no or only mild signs, which may include a hairy patch, dimple, dark spot or swelling on the back at the site of the gap in the spine. MeningoCele typically causes mild problems, with a sac of fluid present at the gap. Myelomenedocele is the most severe form, with poor ability to walk, impaired bladder or bowel control, accumulation of fluid in the brain and tethered spinal cord.