What Is Spina Bifida?

Spina bifida is the most common neural tube defect. These defects are brain disorders that occur if there is a problem with the creation of the neural tube, a process that usually is completed during the first month of pregnancy. Incomplete development in the brain, spinal cord or their protective covering, the meninges, characterizes spina bifida.

Types of Spina Bifida

• The mildest, and most common, form is occulta, which rarely is disabling or causes symptoms. In this type of spina bifida, vertebrae are malformed but covered by a layer of skin.

  Closed neural tube defects, another type of spina bifida, include a variety of defects with malformations of bone, fat or membranes. While there may be no symptoms, these defects also could cause incomplete paralysis or dysfunction of the excretory system. The site of these defects may be visible as a tuft of hair or dimple.

  In meningocele, a third type of spina bifida, there is a protrusion of the meninges through the spinal opening, which may not be covered by skin. There is a range of effects similar to closed neural tube defects.

  The last and most severe type of spina bifida is myelomeningocele, in which an opening in the spine exposes the spinal cord. This can cause incomplete or complete paralysis of the body below the opening. In both myelomeningocele and meningocele, there is typically a sac filled with fluid visible on the back.

Causes

• Although nutritional, genetic and environmental factors are suspected to play a role, with insufficient folic acid in the mother's diet appearing to be a key factor, the exact causes of spina bifida remain unclear.

Prenatal Diagnoses

• Before birth, spina bifida may be found with an ultrasound or a maternal serum alpha-fetoprotein screening done during the second trimester. If abnormal amounts of alpha-fetoprotein are crossing the placenta to the mother's bloodstream, this may show that there is a neural tube defect, although it doesn't suggest specifically that it is spina bifida. Additional tests may help determine the cause.

Postnatal Diagnoses

• Spina bifida is detected before birth in most cases, but some mild cases may be noticed only after birth and very mild cases may never be detected. After birth, spina bifida may be detected by a routine X-ray and examined more closely through an MRI or CT scan.

Treatment

• Although there is no cure for spina bifida, surgery often is performed soon after birth to close the defect in order to prevent infection and further trauma. Surgery is not performed in mild cases. In more severe cases, fetal surgery may be performed.