What is a myelomeningocele?

A myelomeningocele (pronounced my-elo-men-IN-go-seal) is a defect of the backbone (spine) and spinal cord. Before birth, the baby’s spine, the spinal cord and the spinal canal do not form or close normally.

A myelomeningocele is the most serious form of spina bifida.

In babies with myelomeningocele:

  • The bones of the spine (vertebrae) do not form the normal way.
  • A small sac extends through an opening in the spine. A membrane covers the sac.
  • The sac holds cerebrospinal fluid (CSF) and tissues that protect the spinal cord (meninges).
  • The sac may also contain parts of the spinal cord and nerves.

Sometimes the sac opens up. It can open because of normal movements of your baby, either before or during birth.

A myelomeningocele can happen anywhere along the spinal cord. It is most common in the lower back (lumbar and sacral areas). There is nerve damage below the level of the myelomeningocele. As a result of the nerve damage, babies may have symptoms.

Babies with myelomeningoceles lower in the spine have less severe symptoms. Babies with higher myelomeningoceles have more severe symptoms.

Myelomeningocele in Children

Myelomeningoceles are present when a child is born (congenital). About 1 to 5 children in every 1,000 born in the United States have a myelomeningocele. The condition develops during the third week of a woman’s pregnancy.

Doctors do not know exactly what causes myelomeningoceles. Evidence suggests genes may play a role, but the role is not strong. If a woman has 1 child with a myelomeningocele, there is a less than 6% chance that she will have other children with the condition.

We do know what can help prevent myelomeningoceles. 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. Neural tube defects like myelomeningocele have become less common as doctors have learned about the link with folic acid and as more women have taken folic acid supplements during pregnancy.

Myelomeningocele at Seattle Children’s

Seattle Children’s has been a leader for 50 years in providing complete, coordinated care for children with myelomeningoceles. These children often have other complex problems along with their spinal defect and need many types of care as they grow up. Our neurosurgeons close the hole in your baby’s back and work closely with experts from other medical fields – like UrologyNeurodevelopmental and Orthopedics – to make sure your child gets all the care they need.

Doctors in our community usually find myelomeningoceles during exams before the baby is born. They refer about 20 babies with a myelomeningocele to Seattle Children’s each year. Usually, the babies are transferred from the hospital where they are born to Seattle Children’s shortly after their birth. Our neurosurgeons close the defect, usually within 24 to 48 hours of birth. If your newborn is critically ill due to myelomeningocele, we provide specialized care in our Neuro NICU – the only neonatal neurocritical care program in Washington, Wyoming, Alaska, Montana and Idaho.

If you are pregnant and your doctor detects that your baby has a myelomeningocele, you can come to Seattle Children’s Prenatal Diagnosis and Treatment Program for an evaluation. Our doctors will consult on what treatment your baby might need and what to expect.

In some cases, the defect can be closed before your baby is born. We partner with University of California, San Francisco to arrange this surgery (in utero closure or fetal closure) for families in our region. The team from our Prenatal Diagnosis and Treatment Program coordinates the surgery. The surgery is done in California about 24 weeks into the pregnancy. We provide follow-up care for your child in Seattle after the surgery.

Most children with a myelomeningocele develop hydrocephalus. 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 tethered spinal cordChiari malformation and syringomyelia.

Symptoms of Myelomeningocele

A baby with a myelomeningocele has a sac holding parts of the spinal cord sticking though their back. The baby is missing function, like movement or sensation, below the level of the problem. The higher the myelomeningocele is on the baby’s spinal cord, the more function is missing.

Myelomeningocele can cause symptoms that include:

  • Problems moving parts of the body below the opening in the back
  • Lack of sensation in their legs and feet
  • Poor or no bowel and bladder control
  • Twisted or abnormal legs and feet; for example, clubfoot
  • Too much cerebrospinal fluid in the head (hydrocephalus)
  • Problems with how the back of the brain formed (Chiari 2 malformation)
  • Learning differences or delayed milestones (impaired cognitive development)

Diagnosing Myelomeningocele

Your doctor may find the condition before your baby is born. Pregnant women may have a blood test called the quadruple screen to check for signs of certain conditions. If the test shows you have high levels of a protein (maternal alpha fetoprotein, AFP) in your blood, your developing baby might have spina bifida. You may have other tests to make sure of the diagnosis. These include:

  • Ultrasound  
  • Amniocentesis

Seattle Children’s Prenatal Clinic sees pregnant women whose doctors have found a myelomeningocele. Our doctors can consult with you about what to expect and what treatment your baby might need.

Doctors also find myelomeningoceles after a baby is born. The baby may have imaging tests that let doctors see the spine. They include:

  • X-ray
  • Ultrasound
  • Computed tomography (CT) scan  
  • Magnetic resonance imaging (MRI)

Treating Myelomeningocele

As children born with a myelomeningocele grow, they most likely will need treatment such as medicines and physical therapy. Some may need aids like braces, crutches or wheelchairs. Soon after birth, however, treatment for your baby is surgery.

Surgery for Myelomeningocele

The child is in position for repair of his spina bifida. Reprinted from 'Principles of Neurosurgery,' 2nd edition, edited by Setti S. Rengachary, Richard G. Ellenbogen. Copyright 2005, with permission from Elsevier

The child is in position for repair of his spina bifida.

At Seattle Children’s, our expert neurosurgeons and plastic surgeons work together to do surgery to cover your baby’s spinal cord within your baby’s first 48 hours of life to:

  • Limit the risk of infection
  • Prevent more damage to the spinal cord

The surgery does not help your baby develop function that they were not born with.

First, the neurosurgeon closes the covering around the spinal cord (dura mater). Then the neurosurgeon and plastic surgeon close the muscles around the spinal cord. Finally, they close the skin over the open area. The plastic surgeon may need to take a piece of skin from your baby’s back or bottom to make a flap (skin graft) to close the open area.

Closing the defect in spina bifida. Reprinted from 'Principles of Neurosurgery,' 2nd edition, edited by Setti S. Rengachary, Richard G. Ellenbogen. Copyright 2005, with permission from Elsevier

Closing the spinal cord defect in spina bifida.  

Many babies with a myelomeningocele also have too much cerebrospinal fluid in their heads (hydrocephalus). If your baby has severe hydrocephalus at birth, they may need surgery for a temporary drain in the first few days after birth. If a temporary drain is used, a neurosurgeon will place a long-term shunt when your baby is stable.

If your baby does not have hydrocephalus at birth, doctors wait to see if it develops later. If so, neurosurgeons put in a shunt at that time.

Not all babies with a myelomeningocele need a shunt. Most babies who need a shunt get it 4 to 8 weeks after birth.

Fetal surgery

In some cases, neurosurgeons can close the defect before the baby is born (in utero closure or fetal closure). The surgery is done around the 24th week of pregnancy. For families in our region, Seattle Children’s partners with University of California, San Francisco to arrange this surgery. The surgery is done in California. The team from our Prenatal Diagnosis and Treatment Program coordinates the surgery, and we provide follow-up care for your child in Seattle.

If your doctor detects that your baby has a myelomeningocele before birth, you can come to Seattle Children’s Prenatal Diagnosis and Treatment Program for an evaluation. Our doctors can consult with you about what to expect and what treatment your baby might need.

Ongoing Care

Some children with myelomeningoceles have other conditions, like hydrocephalus, tethered spinal cordChiari malformationand syringomyelia, that need treatment.

Often, children with myelomeningoceles have other complex problems related to their nervous systems, such as problems with movement, lack of sensation, and lack of bowel and bladder control. These problems may require long-term care.

Each child is different, and we will tailor your child’s treatment to their needs. Your child’s neurosurgeon will work closely with other experts at Seattle Children’s to assess all your child’s needs and provide long-term coordinated care.

Contact Us

If you would like an appointment, ask your child’s primary care provider for a referral. If you have a referral, call 206-987-2016 to make an appointment.

Providers, see how to refer a patient.

If you have questions, contact us at 206-987-2016 or 844-935-3467 (toll-free).