Spina bifida occulta is a widespread, relatively benign form of spina bifida, a condition characterized by the abnormal formation of one or more vertebrae, according to the National Institute of Neurological Disorders and Stroke. Between 10 and 20 percent of the general population have this condition.
As the human embryo develops, a minute group of specialized cells forms a structure called the neural plate along its back, explains NINDS. The edges of this plate curl in together to form the neural tube, which closes and becomes the embryo's brain and spinal cord. This process typically is completed during the first month of pregnancy. Disruptions occurring during this development often cause neural tube defects, such as spina bifida. Spina bifida occulta is characterized by a layer of skin occluding the gap in the vertebrae, and it usually does not involve disabilities or symptoms.
Most people with spina bifida occulta are diagnosed through X-rays and do not suffer from nervous system problems, according to the Spina Bifida Association. Neurological complications do occur with spina bifida occulta however, most frequently involving a tethered spinal cord. This occurs when the spinal cord is not properly connected to the body and becomes injured or stretched, causing symptoms such as back pain, weakness or pain in the legs, numbness in the back and legs, and changes in bowel or bladder functions.