Children's Hospital Colorado

Myelomeningocele (Spina Bifida)

What is myelomeningocele (spina bifida)?

Myelomeningocele (MMC) is a congenital birth defect of the spine and spinal cord. A serious form of spina bifida, myelomeningocele occurs when a baby's spine (the backbone), spinal cord and spinal canal don't close as they normally would.

This condition develops before birth, usually within the third or fourth week of pregnancy.

How does myelomeningocele occur?

Spina bifida occurs in the first three to four weeks of a woman's pregnancy when the spinal cord is forming. At this point, a baby's developing brain and spine are referred to as the "neural tube."

Normally, during these first few weeks of development, the two sides of a baby's back (known as the neural plate and surrounding tissues) fold to form a tube called the spinal cord. The spinal cord separates from the covering tissues, including the meninges, bone and muscles.

MMC is a neural tube defect in which the bones of the spine don't completely form, resulting in an incomplete spinal canal. Because the spinal canal remains open, the spinal cord and meninges protrude from the baby's back.

Babies with MMC-type spina bifida can have a sac protruding from the opening in the spine. This sac may contain:

  • Cerebrospinal fluid
  • Nerves
  • Parts of the spinal cord

What causes myelomeningocele?

Spina bifida is caused by incomplete closure and development of the fetal spine very early in pregnancy. The exact cause of MMC is not completely understood, but evidence suggests that genes and environmental factors may be involved.

Symptoms and complications of myelomeningocele

MMC is one of the most common birth defects, but its complications – including abnormal spinal cord and nerve function – can range from mild to severe.

The symptoms and complications of MMC include:

  • Abnormal spinal nerve function, including a lack of sensation in the legs and feet
  • Difficulty or inability to walk
  • Poor or no control of the bladder and bowel, known as incontinence
  • Loss of the cerebrospinal fluid that surrounds the nervous system
  • Chiari II malformation: A condition that affects how the back of the brain is formed; because of a Chiari II malformation, the brain is positioned farther down into the upper spinal column than normal. This obstructs the normal flow of fluid out of the brain and causes hydrocephalus.
  • Hydrocephalus, also known as "water in the brain," occurs when there's too much cerebrospinal fluid in the head
  • Abnormal spinal cord function
  • Potential cognitive development such as delayed milestones or learning differences
  • Abnormal development of the feet and legs, such as clubfoot

Are there any signs of myelomeningocele in utero?

No, a pregnant mother won't experience any symptoms indicating her baby has MMC.

How is myelomeningocele diagnosed?

The signs and indicators that a fetus may have myelomeningocele usually present during the tests and screenings that many pregnant mothers undergo.

Prenatal diagnosis of MMC

Your doctor may suspect, identify and diagnose your baby with MMC based off the findings of various prenatal and fetal diagnostic tests, including:

  • The quadruple screen: If this blood test shows high levels of alpha fetoprotein (AFP), the doctor may suspect MMC and follow up with more testing.
  • Ultrasound: Indicators of MMC on an ultrasound include a lemon-shaped head, a lack of movement of the lower extremities, club feet and a visible sac protruding from the spine. 
  • Amniocentesis

A maternal fetal medicine specialist will diagnose a fetus with MMC using an ultrasound.

Post-natal diagnosis of MMC

Your neonatologist or neurosurgeon may also diagnose MMC after your baby is born using imaging of their spine, such as:

Myelomeningocele treatment options

While an MMC diagnosis may be life-changing, there are myelomeningocele treatment options available that may help your child thrive – both during pregnancy and after they've entered the world.

And at the Colorado Fetal Care Center, your treatment options are more than just that – they're carefully designed strategies to give your baby the best quality of life. We have a specialized team dedicated to treating babies with myelomeningocele. And as one of the nation's top fetal care centers, we offer some of the most innovative fetal therapies available.

Before determining if a patient qualifies for MMC fetal surgery, our fetal care team works closely with you and collaborates with other specialists. Before deciding on a course of action, we evaluate your baby's particular condition and the severity of their MMC using fetal diagnostic tests like ultrasound, MRI and echocardiography. Only then do we design and offer a treatment plan.

Prenatal myelomeningocele repair

For some families, our fetal experts offer to treat MMC before the baby is even born by performing a myelomeningocele repair in utero. We choose to perform this open fetal surgery if it can:

  • Give a fetus their best chance at surviving and thriving
  • Improve outcomes
  • Prevent other injuries or complications from developing
  • Prevent further neural damage and more cerebrospinal fluid from leaking
  • Decreases the chances the baby will need a shunt down the line

When a fetus has an open neural tube defect like MMC, their nerves are exposed to elements that could cause further harm, like amniotic fluid, cerebrospinal fluid and direct trauma.

What to expect from open fetal surgery for MMC spina bifida repair

During the MMC fetal surgery, a maternal fetal medicine specialist will make an incision in the abdomen to open the uterus and expose the defect in your baby's spine. Then a highly specialized pediatric neurosurgeon will repair the myelomeningocele and close the skin of your baby's back over the opening to protect their still-developing neural tissue – all while you're still pregnant.

Before the procedure begins, your obstetric and fetal anesthesiologist will administer anesthesia to put you to sleep and relax the uterus; the anesthesia passes through the placenta to your unborn child, allowing the surgical team to open the uterus, perform the in-utero MMC repair and close the uterus – all without interfering with your pregnancy.

Once the procedure is finished, we leave the baby to keep growing and developing, all while monitoring closely with frequent ultrasounds. We’ll then deliver your baby via cesarean section around 37 weeks' gestation.

What are the risks of open fetal surgery?

Risks to the mother from open fetal surgery may include obstetrical complications and potential scarring that could affect future pregnancies.

There is some risk to the fetus during in-utero surgery, but the team at the Colorado Fetal Care Center has successfully performed over 50 prenatal spina bifida repairs. In our dedicated fetal surgery suite, our team of specialists is ready and capable of handling anything that may occur during the treatment or birth process.

Post-birth myelomeningocele treatment

If your fetal care team decides the best course of action is to repair your baby’s MMC after they're born, the treatment includes:

  • Frequent ultrasounds during pregnancy to monitor fetal growth
  • Delivering the baby via cesarean section (C-section) at full term
  • An evaluation by your baby's care team and neurosurgeon after delivery
  • Surgery to close the spina bifida within the first two days of life

Your child's care team will also evaluate them for signs of increased pressure in their brain (a condition known as hydrocephalus). If present, they'll likely insert a ventriculoperitoneal shunt, which is a tube that helps to drain excess spinal fluid from the brain into the abdominal cavity.

And care doesn't stop once your child is born. They'll receive follow-up care and be monitored by a multidisciplinary team of neurology, orthopedic, occupational therapy, pediatric, physical therapy and urology specialists, and others as needed.

Why choose the Colorado Fetal Care Center to treat your baby's myelomeningocele? 

Our team at the Colorado Fetal Care Center has the experience and expertise to meet any of your and your baby's needs. From pregnancy management and diagnosis, to treatment and long-term pediatric subspecialty care, we have the capabilities, team and facilities to provide the highest quality care and best possible outcome. 

Our average delivery age for babies who've undergone in-utero MMC repair is 34 weeks, meaning we give your baby as much time as possible to grow. 

When you come to the Colorado Fetal Care Center for the diagnosis and treatment of your baby's myelomeningocele, you're cared for by a dedicated team of experts who have spent years researching, innovating and performing this treatment. 

Comprehensive, consistent care 

We make it easier on mom, baby and the whole family by surrounding you with the same faces every day. You'll meet with every provider on your care team on day one. And this same team will be with you every step of the way, so they know all the details of your case. And we know that your baby's needs don't end at delivery, which is why we make the transition to the NICU, specialty care and home as seamless as possible. 

No question goes unanswered 

All of these specialists and providers are under the same roof at Children's Colorado. This means that your questions are answered faster, you have instant access to our expertise, and we're ready to handle anything that may arise. 

We keep families together 

We know how nervous and excited you are to meet your new baby, which is why we keep your family close together. In fact, Children's Colorado is one of the few children's hospitals in the nation with a labor and delivery unit. 

Our Maternal Fetal Care Unit (MFCU) and Level IV Neonatal Intensive Care Unit (NICU) are right down the hall from each other, so you're able to easily visit your newborn as much as possible, and this is all under the same roof as nationally-ranked pediatric care. 

If you are interested in learning more about our fetal care specialists, please contact the Colorado Fetal Care Center at 1-855-413-3825.

Myelomeningocele FAQs

What's the long-term outlook for a baby with myelomeningocele?

Spina bifida is a lifelong disability and the symptoms, complications and long-term outlook for MMC spina bifida patients are different for every person. The severity of MMC complications depends on:

  • The location of myelomeningocele on the spine
  • The size of the vertebral opening

MMC can develop anywhere along the spinal cord, but it happens most commonly in a baby’s lower back – known as the lumbar and sacral regions. Nerve damage occurs below the point of the spine where the myelomeningocele has developed.

Therefore, babies with MMC lower in the spine tend to have less severe symptoms, while those with MMC higher in the spine tend to experience more severe symptoms because the nerve damage affects more of the spine.

For example:

  • Some babies may be able to move their knees and only have problems with their ankles
  • Others may have weakness of the knees
  • Only 5 to 10% will have significant swallowing and breathing problems

The milder version of MMC occurs when the vertebral openings are too small for the spinal cord to protrude through. In the more severe category, a portion of the spinal cord protrudes through the vertebral opening.

Babies born with these mild forms of spina bifida and MMC are unlikely to suffer long-term health problems and can lead normal lives, while a baby with severe MMC requires dedicated medical attention.

How many types of spina bifida are there?

Spina bifida can be closed or open. If the nerves are covered with skin or fatty tissue, the defect is closed. If the nerves are not covered by anything, the defect is open.

Open defects tend to be more severe, because the nerves are damaged by amniotic fluid and contact with the uterine environment and wall.

There are four different types of spina bifida:

  • Spina bifida occulta: Occulta, meaning "hidden," is the mildest and most common form of spina bifida; it rarely causes complications or symptoms. With this condition, there's a small gap in the spine, but it's covered by a layer of skin, and there's no opening or sac on the baby’s back. Spina bifida occulta rarely causes disability or symptoms.
  • Closed neural tube defects: This form of spina bifida consists of a diverse group of spinal cord defects where there is malformation of the fat, bone or membranes of a fetus's spine. Usually, a closed neural tube defect causes few or no complications, although some individuals may experience other symptoms, including partial paralysis.
  • Myeloschisis: Myeloschisis is the most severe form of spina bifida aperta, an open neural tube defect. With myeloschisis, a fetus's neural folds don't close, leaving the nerve tissue fully exposed.
  • Myelomeningocele (MMC): MMC is a severe open neural tube defect, occurring when the fetus's spinal cord, nerves and meninges are exposed through the opening in their spine.

Can you get myelomeningocele at any age?

No, MMC and the other forms of spina bifida are congenital birth defects, meaning a baby is born with this defect. However, sometimes the milder forms of spina bifida occulta aren't diagnosed until after the baby is born.

Helpful resources for MMC

  • The Spina Bifida Association hosts yearly events for families and children affected by spina bifida. They provide a great way to meet other families facing similar challenges. They host events every year for families and children. It is a good way to meet other families facing similar challenges.
  • The National Organization for Rare Disorders (NORD) supports the identification, treatment and cure of rare disorders such as MMC via education, advocacy, research and patient services.
  • The Spina Bifida Association (SBA) aims to enhance the lives of those affected by spina bifida. SBA provides valuable resources, support services and educational materials for expectant mothers carrying a child diagnosed with MMC, as well as the kids, teenagers and adults living with MMC spina bifida.

Myelomeningocele success stories

Read this family's journey and see how the Colorado Fetal Care Center was there through diagnosis, treatment and beyond – giving them hope for their son.

For baby Peyton, expert spina bifida care before and after birth made all the difference. Read her story to see how prenatal spina bifida surgery and our doctor's expertise treated her myeloschisis and side-stepped a hydrocephalus scare.

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