Myelomeningocele (children)

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Spina bifida

Spina bifida (degrees of severity)

Myelomeningocele is a birth defect in which the backbone and spinal canal do not close before birth. The condition is a type of spina bifida.

Spina bifida; Cleft spine

Myelomeningocele is one of the most common birth defects of the central nervous system. It is a neural tube defect in which the bones of the spine do not completely form, and the spinal canal is incomplete. This allows the spinal cord and meninges (the membranes covering the spinal cord) to protrude out of the child's back.

Spina bifida includes any congenital defect involving insufficient closure of the spine. Myelomeningocele accounts for about 75% of all cases of spina bifida and may affect as many as 1 out of every 800 infants. The rest of the cases are most commonly spina bifida occulta (where the bones of the spine do not close, the spinal cord and meninges remain in place, and skin usually covers the defect) and meningoceles (where the meninges protrude through the vertebral defect but the spinal cord remains in place).

The cause of myelomeningocele is unknown. However, folic acid deficiency is thought to play a part in neural tube defects. Also, if a child is born with myelomeningocele, subsequent children in that family have a higher risk than the general population.

A viral cause or trigger has been theorized because there is a higher incidence of the defect in children born in the early winter months. Research also indicates possible environmental factors such as radiation.

Protrusion of the spinal cord and meninges damages the spinal cord and nerve roots, causing a decrease or lack of function of body areas controlled at or below the defect. Symptoms are related to where the defect is on the spinal column. Most defects occur in the lower lumbar or sacral areas of the back (the lowest areas of the back) because this area is normally the last part of the spine to close.

Other congenital disorders may also be present in the child, usually disorders of the spinal cord or the musculoskeletal system such as hydrocephalus (which may affect as many as 90% of children with myelomeningocele), syringomyelia, hip dislocation, or similar disorders.

Review Date: 12/06/2006
Reviewed By: Ian Marshall, MD, Division of Pediatric Endocrinology, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, NJ. Review provided by VeriMed Healthcare Network.