Question

Give an example that shows variable expression of spina bifida.

Answer 1

Spina bifida is characterized by the incomplete development of the brain, spinal cord, and/or meninges There are four types of spina bifida: occulta, closed neural tube defects, meningocele, and myelomeningocele. Occulta is the mildest and most common form in which one or more vertebrae are malformed. The name "occulta," which means "hidden," indicates that a layer of skin covers the malformation, or opening in the vertebrae. This form of spina bifida, present in 10-20 percent of the general population, rarely causes disability or symptoms. Closed neural tube defects make up the second type of spina bifida. This form consists of a diverse group of defects in which the spinal cord is marked by malformations of fat, bone, or meninges. In most instances there are few or no symptoms; in others the malformation

symptoms; in others the malformation causes incomplete paralysis with urinary and bowel dysfunction. In the third type, meningocele, spinal fluid and meninges protrude through an abnormal vertebral opening; the malformation contains no neural elements and may or may not be covered by a layer of skin. Some individuals with meningocele may have few or no symptoms while others may experience such symptoms as complete paralysis with bladder and bowel dysfunction. Myelomeningocele, the fourth form, is the most severe and occurs when the spinal cord/neural elements are exposed through the opening in the spine, resulting in partial or complete paralysis of the parts of the body below the spinal opening. The impairment may be so severe that the affected individual is unable to walk and may have bladder and bowel dysfunction.