A myelomeningocele (pronounced my-e-lo-MENING-o-seal) is a congenital (present at birth) deformity of the spine and spinal cord, which do not form and close normally. The spinal cord is open to the air. A myelomeningocele is the most serious form of spina bifida. It can occur anywhere along the spinal cord. A lesion, like a sac, at the deformity site contains cerebrospinal fluid and tissues that protect the brain called the meninges. It may also contain portions of the spinal cord.
This causes abnormal body functions and malformations at and below this point. These can include problems with physical movement, loss of sensation (such as hot or cold), loss of bowel and bladder control, twisted or abnormal legs and feet (such as a club foot), hydrocephalus.