Open Neural Tube Defects (ONTD) and Myelomeningocele (MMC)

Learning that your pregnancy is affected by myelomeningocele can be overwhelming. At University of Chicago Medicine, you will not navigate this alone. At University of Chicago Medicine’s Fetal and Neonatal Care Center (FNCC), we bring together maternal-fetal medicine specialists (high-risk obstetricians), pediatric neurosurgeons, neonatologists, neurologists, urologists and a full support team — all working together to provide you and your newborn with the most comprehensive, compassionate care possible.

Call us at 844-823-3825 to schedule a consultation.

Find a maternal-fetal medicine specialist

What Are Open Neural Tube Defects?

The neural tube is the structure in a developing embryo that becomes the brain and spinal cord. It normally closes completely within the first 28 days of pregnancy — often before a mother even knows she is pregnant. Open neural tube defects (ONTDs) occur when part of that tube fails to close, leaving the brain or spinal cord exposed.

Myelomeningocele, often called MMC, is the most common and most severe type of open neural tube defect. It is also the most severe form of spina bifida.

What Is Myelomeningocele?

In myelomeningocele, a portion of the spinal cord and the nerves that branch from it are not protected by skin or bone. Instead, they protrude through an opening in the spine — usually in the lower back — and may be enclosed in a fluid-filled sac visible at birth. Because these nerves are exposed, they can be damaged before or during delivery.

Myelomeningocele affects about 3 to 4 out of every 10,000 live births in the United States. The good news is that modern care — including the option of surgery before birth — has dramatically improved outcomes. Most children with myelomeningocele grow into adulthood, and many walk, attend regular school and live independently.

Almost all children with myelomeningocele also have two related conditions that need ongoing attention:

Chiari II malformation: The brain has a small section at its base — called the brainstem and cerebellum — that controls basic functions like breathing and swallowing. In children with myelomeningocele, this section sits lower in the skull than it should, which can put pressure on it and interfere with those functions.
Hydrocephalus: The brain and spinal cord are normally cushioned by a clear fluid that flows around them. In hydrocephalus, that fluid builds up inside the brain because it cannot drain the way it should. This puts pressure on the brain and usually requires a surgical procedure to redirect the fluid safely away.

What Can Myelomeningocele Cause?

The effects of myelomeningocele depend largely on where along the spine the opening is located. The higher up the defect, the more of the spinal cord is affected. Common challenges include:

Leg Weakness or Paralysis

The spinal cord carries the signals that tell your legs to move.
When part of it is affected by myelomeningocele, those signals are disrupted.
How much depends on where along the spine the opening is located — the lower the defect, the more leg function is preserved.
The higher the opening is on the spine, the more of the cord is involved and the greater the impact on leg strength and mobility.
The lower the opening, the more leg function is preserved.
Many children with lower spine defects walk on their own.
Those with defects higher up the spine may walk with the help of braces or crutches, or use a wheelchair for getting around.

Bladder and Bowel Problems

Hydrocephalus

The brain is normally cushioned by a clear fluid that flows around it and drains away on its own. With myelomeningocele, that drainage is often blocked, causing fluid to build up and press on the brain.
Between 80% and 90% of children need a procedure to redirect that fluid safely.
The two most common options are a shunt (a small tube placed under the skin that carries fluid to the abdomen) or a minimally invasive procedure called an endoscopic third ventriculostomy, or ETV, that creates a new drainage path without leaving permanent hardware behind.

Bone and Foot Differences

Because the nerves controlling muscles and movement in the lower body are affected, children with myelomeningocele often develop orthopedic differences that need specialized care, including:

Club feet (feet turned inward at birth)
Scoliosis (an abnormal sideways curve of the spine)
Hip problems (where weakened muscles cause the hip joint to sit unevenly).

All are treatable, and care is tailored to each child's goals and level of function.

Tethered Spinal Cord

After the spinal opening is repaired, scar tissue can form at the repair site.
As a child grows taller, that scar tissue can tug on the spinal cord — like a cord that is too short — pulling it in ways it is not meant to move.
This can cause new symptoms years after surgery, including back or leg pain, changes in walking, new weakness or shifts in bladder and bowel control.
If tethering is causing problems, surgery to release the cord can help.

Learn more about tethered cord syndrome.

Skin Sensitivity

Below the level of the spinal defect, children often have reduced or no feeling in their skin.
Because they cannot feel pressure or pain the way others can, they may not notice when staying in one position too long is causing damage.
This makes pressure sores — areas of skin breakdown from prolonged pressure — a lifelong concern, particularly on the feet, buttocks and hips.
Regular skin checks and pressure-relieving strategies are an important part of daily care.

How Is Myelomeningocele Diagnosed?

At UChicago Medicine, we routinely perform first-trimester early anatomy scans between 11 and 13 weeks for high-risk pregnancies, meaning we may identify myelomeningocele earlier than many other centers. Most cases are found before birth, opening the door to earlier intervention. Diagnosis typically begins with one of the following:

First-trimester anatomy ultrasound:

This is a unique ultrasound that takes place between 11 to 13 weeks of pregnancy.
The University of Chicago is one of the few centers in the area which performs this type of ultrasound.
This is performed for patients at high-risk for congenital abnormalities
If myelomeningocele is present, your doctor may see an opening in the spine or a fluid-filled sac on the fetus's back.

Second-trimester anatomy ultrasound:

This is a routine pregnancy ultrasound that takes a detailed look at developing fetus developing body around 18 to 22 weeks.
If myelomeningocele is present, your doctor may see an opening in the spine or a fluid-filled sac on the fetus's back.
The shape of the baby's skull and the position of part of the brain may also look slightly different than usual. These are recognized patterns that help doctors identify the condition early.

Elevated maternal blood test:

A routine blood draw done in the first or second trimester measures a protein called alpha-fetoprotein, or AFP.
When AFP levels are higher than expected, it can be a sign that the spinal cord is not fully covered — prompting your doctor to take a closer look with imaging.

Once myelomeningocele is suspected, families are referred to the Fetal and Neonatal Care Center at the University of Chicago Medical Center. Additional testing typically includes:

Fetal MRI:

An MRI uses magnetic fields — not radiation — to create detailed images of your baby while still in the womb.
It shows exactly where along the spine the opening is located, how much fluid has built up around the brain, and whether there are any other differences in brain development.
This information is essential for planning your baby's care.

Amniocentesis:

A small sample of the fluid surrounding the fetus in the womb is tested to look at your baby's fetal genetics. We offer comprehensive genetic testing — not just a standard chromosome count — and all families will meet with a genetic counselor who can help interpret results and discuss what they may mean for your care.
Most babies with myelomeningocele have typical chromosomes, but this test rules out other conditions that could affect care decisions.
It is offered to all families, though it is your choice whether to have it.

Fetal echocardiogram: This is an ultrasound focused specifically on your baby's heart, used to make sure the heart is developing as expected.

What Are Options for Myelomeningocele Management?

Myelomeningocele requires decisions that begin before birth and continue throughout your child's life. The sections below explain the main approaches to managing myelomeningocele, from surgery before birth through the ongoing, coordinated care your child will need as they grow.

Surgery Before Birth (Prenatal Closure)

For eligible families, maternal-fetal surgery to close the opening before birth is now a well-established option. In 2011, a major NIH-sponsored clinical trial called the Management of Myelomeningocele Study (MOMS) showed that closing the defect before 26 weeks of pregnancy produces significantly better outcomes than waiting until after birth:

The need for a brain shunt by age 1 dropped from 82% to 40%.
Twice as many children walked independently at 30 months (42% vs. 21%).
Brainstem position related to the Chiari II malformation improved in most babies.
Motor function was, on average, two spinal levels better than expected from the location of the defect.

These benefits come with real tradeoffs. Prenatal surgery is associated with a risk of premature rupture of membranes, the need for prolonged hospitalization, and the potential for preterm delivery. The need for a cesarean delivery depends on the surgical approach used and will be discussed with you by your care team. Not every family or baby qualifies. Our team will help you understand whether this option is right for you.

Important note on bladder and bowel function: Current evidence does not consistently show that in utero repair improves bladder or bowel dysfunction. This is a significant concern for many families, and our team will discuss what current data show and what to expect in detail during your consultation.

Pregnancy Termination (Abortion)

A diagnosis of myelomeningocele can raise profound questions about your options. UChicago Medicine is one of the few fetal care centers that provides comprehensive reproductive care — including pregnancy termination (abortion) — for patients with prenatally-diagnosed conditions. Our team will present all options clearly and support whatever decision you and your family make. Please speak with your care team to discuss your options in confidence.

Surgery After Birth (Postnatal Closure)

When prenatal surgery is not chosen or not possible, the newborn's exposed spinal tissue is carefully covered with a sterile, saline-soaked dressing at birth. Surgery to close the opening is performed within 24 to 48 hours. This early closure significantly reduces the risk of infection and is the standard of care for babies who did not have prenatal repair.

During the operation, the neurosurgical team carefully separates the exposed nerve tissue, folds it back into a tube, reconstructs the protective coverings of the spinal cord and closes the skin over the defect.

Managing Hydrocephalus As Your Child Grows

After the spinal defect is closed, most children with myelomeningocele develop hydrocephalus and need a procedure to drain excess spinal fluid from the brain. The two main options are:

Ventriculoperitoneal (VP) shunt: A thin tube that carries spinal fluid from the brain to the abdomen, where the body absorbs it. Shunts are effective but may need to be replaced or adjusted over a lifetime.
Endoscopic third ventriculostomy with choroid plexus cauterization (ETV/CPC): A minimally invasive procedure that creates a new drainage pathway without leaving a permanent shunt in place. It is most effective in carefully selected infants.

Ongoing Care

Myelomeningocele is not a one-time diagnosis — it is a lifelong partnership between your family and a team of specialists. As your child grows, the team at UChicago Medicine coordinates:

Neurosurgery: for hydrocephalus management, tethered cord monitoring and Chiari II follow-up
Pediatric urology: for bladder and kidney health
Orthopedics: for foot, hip and spine care
Physical and occupational therapy: to support mobility and independence
Developmental pediatrics: for learning and developmental support

Social work: for family support and navigating resources

What to Expect Before, During and After Delivery

Before Birth

From the moment you come to us, you will be surrounded by our Maternal-Fetal Medicine (MFM) team (high-risk obstetricians) who know this condition well and is focused on you and your pregnancy. You will have a detailed ultrasound and a fetal MRI so we can see exactly what we are working with. You will also meet with a genetic counselor — a specialist who helps families understand test results and what they may mean — and have the option of amniocentesis if you choose.

Most importantly, you will sit down with our full care team, which includes high-risk obstetricians, pediatric neurosurgeons, pediatric neurologists, pediatric urologists, newborn intensive care specialists and a social worker. You will also be connected with our fetal nurse navigators, who serve as your primary point of support and guide you through every step of this process. Together, we will explain your options clearly, answer your questions and build a plan that reflects your family's needs and wishes. You will not have to figure this out alone.

Delivery Planning

We will work closely with you to plan the safest possible delivery. The route of delivery — vaginal or cesarean — depends on several factors, including the size and location of the lesion, and will be determined together with our neurosurgical team based on your specific situation. Our Level IV NICU — the highest level of newborn intensive care available, and one of the few in Illinois — is located just steps from our delivery rooms, inside Comer Children's Hospital itself. This means your newborn can transition immediately into the highest level of specialized care, without being transported to a separate building — a distinction that sets us apart from most other fetal care centers in the region.

After Birth

The moment your newborn arrives, our newborn care team will gently protect the spinal sac on the newborn’s back to prevent infection while preparing for surgery. Within the first day or two of life, our pediatric neurosurgical team will perform an operation to close the opening in the spine — a critical step that significantly reduces the risk of infection and further nerve damage.

In the days that follow, we will watch closely for signs of fluid buildup in the brain and treat it promptly if needed. Our bladder specialists, orthopedic surgeons and physical therapists will also begin getting involved early, so that every part of your newborn's care is coordinated and nothing falls through the cracks.

Warning Signs to Know

Once your child is home, it is important to know when to call your care team right away. Contact us immediately if you notice:

Head growing faster than expected, bulging soft spot, vomiting, unusual sleepiness or new eye crossing: possible shunt problem
New snoring, breath-holding, choking while feeding or a weak or high-pitched cry: possible Chiari II symptoms
New back pain, leg weakness, changes in walking or loss of bladder control a child had mastered: possible tethered spinal cord

Sudden fever in a child who has a shunt: call your care team the same day

Frequently Asked Questions About Myelomeningocele

Leg Weakness or Paralysis

The spinal cord carries the signals that tell your legs to move.
When part of it is affected by myelomeningocele, those signals are disrupted.
How much depends on where along the spine the opening is located — the lower the defect, the more leg function is preserved.
The higher the opening is on the spine, the more of the cord is involved and the greater the impact on leg strength and mobility.
The lower the opening, the more leg function is preserved.
Many children with lower spine defects walk on their own.
Those with defects higher up the spine may walk with the help of braces or crutches, or use a wheelchair for getting around.

Bladder and Bowel Problems

Hydrocephalus

The brain is normally cushioned by a clear fluid that flows around it and drains away on its own. With myelomeningocele, that drainage is often blocked, causing fluid to build up and press on the brain.
Between 80% and 90% of children need a procedure to redirect that fluid safely.
The two most common options are a shunt (a small tube placed under the skin that carries fluid to the abdomen) or a minimally invasive procedure called an endoscopic third ventriculostomy, or ETV, that creates a new drainage path without leaving permanent hardware behind.

Bone and Foot Differences

Because the nerves controlling muscles and movement in the lower body are affected, children with myelomeningocele often develop orthopedic differences that need specialized care, including:

Club feet (feet turned inward at birth)
Scoliosis (an abnormal sideways curve of the spine)
Hip problems (where weakened muscles cause the hip joint to sit unevenly).

All are treatable, and care is tailored to each child's goals and level of function.

Tethered Spinal Cord

After the spinal opening is repaired, scar tissue can form at the repair site.
As a child grows taller, that scar tissue can tug on the spinal cord — like a cord that is too short — pulling it in ways it is not meant to move.
This can cause new symptoms years after surgery, including back or leg pain, changes in walking, new weakness or shifts in bladder and bowel control.
If tethering is causing problems, surgery to release the cord can help.

Learn more about tethered cord syndrome.

Skin Sensitivity

Below the level of the spinal defect, children often have reduced or no feeling in their skin.
Because they cannot feel pressure or pain the way others can, they may not notice when staying in one position too long is causing damage.
This makes pressure sores — areas of skin breakdown from prolonged pressure — a lifelong concern, particularly on the feet, buttocks and hips.
Regular skin checks and pressure-relieving strategies are an important part of daily care.

Meet Our Fetal and Neonatal Care Specialists

At the Fetal and Neonatal Care Center, your maternal-fetal medicine physician leads your care team in providing the best care possible for you and your baby.

We're also one of few birth centers in Illinois with a Level IV NICU just steps away, which enables us to support seamless transitions to neonatal care for babies born with the most complex and acute conditions and illnesses.

Refer a Patient: 1-844-UC-FETAL (1-844-823-3825)

Maternal-Fetal Medicine Physicians

Shakeela Faulkner, MD

Maternal-Fetal Medicine

Jessica Peterson, MD

Obstetrics and Gynecology (OB/GYN)

Ashish Premkumar, MD, PhD

Maternal-Fetal Medicine

Andrew C. Rausch, MD

Obstetrics and Gynecology (OB/GYN)

Convenient Locations for Maternal-Fetal Care

Request an Appointment

We are currently experiencing a high volume of inquiries, leading to delayed response times. For faster assistance, please call 1-888-824-0200 to schedule your appointment.

If you have symptoms of an urgent nature, please call your doctor or go to the emergency room immediately.

By submitting this form you acknowledge the risk of sending this information by email and agree not to hold the University of Chicago or University of Chicago Medical Center liable for any damages you may incur as a result of the transfer or use of this information. The use or transmittal of this form does not create a physician-contact relationship. More information regarding the confidentiality of this request can be found in our Privacy Policy.

* Indicates required field