Spina bifida is a birth defect that involves the incomplete development of the spinal cord or its coverings. The term spina bifida comes from Latin and literally means "split" or "open" spine.
Spina bifida occurs at the end of the first month of pregnancy when the two sides of the embryo's spine fail to join together, leaving an open area. In some cases, the spinal cord or other membranes may push through this opening in the back. The condition usually is detected before a baby is born and treated right away.
Types of Spina Bifida
The causes of spina bifida are largely unknown. Some evidence suggests that genes may play a role, but in most cases there is no familial connection. A high fever during pregnancy may increase a woman's chances of having a baby with spina bifida. Women with epilepsy who have taken the drug valproic acid to control seizures may have an increased risk of having a baby with spina bifida.
The two forms of spina bifida are spina bifida occulta and spina bifida manifesta.
Spina bifida occulta is the mildest form of spina bifida (occulta means hidden). Most children with this type of defect never have any health problems, and the spinal cord is often unaffected.
Spina bifida manifesta includes two types of spina bifida:
- Meningocele involves the meninges, the membranes responsible for covering and protecting the brain and spinal cord. If the meninges push through the hole in the vertebrae (the small, ring-like bones that make up the spinal column), the sac is called a meningocele.
- Myelomeningocele is the most severe form of spina bifida. It occurs when the meninges push through the hole in the back, and the spinal cord also pushes though. Most babies who are born with this type of spina bifida also have hydrocephalus, an accumulation of fluid in and around the brain.
Because of the abnormal development of and damage to the spinal cord, a child with myelomeningocele typically has some paralysis. The degree of paralysis largely depends on where the opening occurs in the spine. The higher the opening is on the back, the more severe the paralysis tends to be.
Children with spina bifida often have problems with bowel and bladder control, and some may have attention deficit hyperactivity disorder (ADHD) or other learning difficulties, such as hand-eye coordination problems.