Spina Bifida

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 embryo's back. The condition can typically be 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 be involved, 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.

There are two forms of spina bifida — 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. The spinal cord is often unaffected.

Spina bifida manifesta includes two types of spina bifida, meningocele and myelomeningocele.

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 the myelomeningocele form of spina bifida 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.

Diagnosing Spina Bifida

Expectant parents may be able to find out if a baby has spina bifida by taking certain kinds of prenatal tests. The maternal serum alpha-fetoprotein (AFP) test, performed between the 16th and 18th weeks of pregnancy, measures the amount of alpha-fetoprotein that the fetus produces. The doctor will measure the amount of AFP in the mother's blood. If the amount is high, the test is repeated because in many cases, high AFP readings are false. If the amount is high once more, another test or tests will be done to double-check and confirm the diagnosis.

Doctors may also use ultrasound to see if a baby has spina bifida; in some cases, the spinal defect can be seen on the ultrasound study. Amniocentesis can also help determine whether a baby has spina bifida. A needle is inserted through the mother's belly and into the uterus to collect fluid that is tested for AFP.