Chromosomal and Genetic Conditions
What Is a Myelomeningocele?
A view of a myelomeningocele or spina bifida, a formerly common birth defect
A myelomeningocele (pronounced my-e-lo-MENING-o-seal) is a defect of the backbone (spine) and spinal cord. Before birth, the baby's backbone, spinal cord and the structure they float in (spinal canal) do not form or close normally.
A myelomeningocele is the most serious form of spina bifida. In babies with a myelomeningocele, the bones of the spine (vertebrae) don't form properly. This lets a small sac extend through an opening in the spine. The sac is covered with a membrane. It holds cerebrospinal fluid (CSF) and tissues that protect the spinal cord (meninges). The sac may also contain portions of the spinal cord and nerves. The sac itself may be opened up either before birth or during the birth.
A myelomeningocele can occur anywhere along the spinal cord. It is most common in the lower back (lumbar and sacral areas). Babies lose function below the level of the problem. So, the higher the myelomeningocele is on the baby's back, the more loss of function occurs.
Myelomeningocele in Children
Myelomeningoceles are present when a baby is born (congenital). About one to five babies in every 1,000 born in the United States have a myelomingocele. The condition develops during the third week of a woman's pregnancy.
Doctors don't know exactly what causes myelomeningoceles. But there probably is a genetic component. If a woman has one child with a myelomeningocele, there is a 3% to 5% chance that other children she has will also have the condition.
While we don't know the exact cause of myelomeningoceles, doctors do know what can help prevent them. Early in pregnancy, it is very important for women to get enough folic acid in their diets. This vitamin helps the baby's neural tube develop properly. The neural tube develops into the baby's brain and spinal cord.
Myelomeningocele at Seattle Children's
Neurosurgeons at Seattle Children's treat many children with myelomeningoceles. These children often have other complex problems. In our multidisciplinary clinic, our neurosurgeons work closely with experts from other medical fields to make sure your child gets the care they need as they grow.
Doctors in our community usually find myelomeningoceles during exams before the baby is born. They refer about 10 to 20 babies with myelomeningocele to Seattle Children's each year. The babies usually are transferred from the hospital where they are born to Seattle Children's shortly after their birth. Our neurosurgeons are on hand to close the hole in the baby's back, usually within 24 to 48 hours of birth.
Most children with a myelomeningocele develop hydrocephalus, or too much cerebrospinal fluid in parts of the brain. Neurosurgeons at Seattle Children's have a great deal of experience putting in shunts, a common treatment for hydrocephalus. We also have a lot of experience treating children with the related problems of spinal cord tethering, Chiari malformation and syringomyelia.