Myelomeningocele (Spina Bifida Aperta)

Our Specialists for Myelomeningocele (Spina Bifida Aperta)

Myelomeningocele is not a one-operation diagnosis — it is a lifelong partnership between your family and a team of specialists. Our pediatric neurosurgeons work alongside maternal-fetal medicine, neonatology, pediatric urology, orthopedics, physical therapy, and social work to plan care from the first prenatal ultrasound through the transition to adult services.

Arthur J. DiPatri Jr., M.D.

Director, Pediatric Neurosurgery

Dr. DiPatri has been performing pediatric neurosurgery for over 27 years. He's dual board-certified in both neurological surgery and pediatric neurological surgery, and he's Chief of Pediatric Neurosurgery for the Chicagoland Children's Health Alliance, meaning he oversees pediatric brain care across Comer, Advocate, and Endeavor Health. He came to UChicago after 22 years at Lurie Children's Hospital, with additional fellowship training at Boston Children's Hospital. Dr. DiPatri is a fellowship-trained pediatric neurosurgeon with more than two decades of experience caring for children with spina bifida, hydrocephalus, and the Chiari II malformation — the three neurosurgical problems every child with myelomeningocele faces. If your baby needs newborn closure, a shunt or ETV for hydrocephalus, a posterior fossa decompression for symptomatic Chiari II, or a later tethered cord release, Dr. DiPatri is one of the surgeons who sees these children weekly and follows them through the multidisciplinary spina bifida clinic into adolescence.

What Is Myelomeningocele?

Myelomeningocele is the most severe and most common form of open spina bifida (spina bifida aperta). Very early in pregnancy — within the first 28 days after conception, often before a mother even knows she is pregnant — the embryo's neural tube, which will become the brain and spinal cord, fails to close completely along the back. The result is a segment of spinal cord and nerve roots that never get covered by skin, bone, or the normal protective membranes. At birth, you can see a fluid-filled sac on the baby's back, usually in the lower lumbar or sacral spine, with exposed neural tissue at its center.

Because the spinal cord below the defect never developed normally, children with myelomeningocele have some degree of paralysis, loss of sensation, and bladder and bowel dysfunction below the level of the lesion. Almost all of them also have a Chiari II malformation, in which the lower part of the brainstem and cerebellum sit too low in the skull, and most develop hydrocephalus (a buildup of spinal fluid on the brain) that needs surgical treatment.

Myelomeningocele affects about 3 to 4 out of every 10,000 live births in the United States today — roughly half the rate of 30 years ago, thanks mostly to folic acid food fortification. It is still one of the most common serious birth defects and the most common permanently disabling one compatible with long-term survival.

The outlook has improved enormously over the last 50 years. When specialized care and early closure became the standard in the 1970s, most children survived infancy for the first time. The MOMS trial in 2011 added a new option — surgery on the baby before birth — that can reduce the burden of hydrocephalus and improve motor function. And multidisciplinary spina bifida clinics, like the one at Comer Children's, now coordinate neurosurgery, urology, orthopedics, and rehabilitation so that families don't have to navigate ten separate specialists on their own.

What Does It Look Like and What Should You Expect?

Because myelomeningocele is almost always obvious at birth — and usually diagnosed even earlier on a prenatal ultrasound — the question most families ask isn't "what are the symptoms?" but rather "what should we expect as our child grows?" The honest answer is that it depends heavily on where along the spine the lesion sits. The higher up the defect, the more of the spinal cord is affected.

At birth

• A visible sac or open area on the lower back, usually in the lumbar or sacral region
• Weakness, floppiness, or lack of movement in the legs and feet below the level of the defect
• Club feet or other foot and ankle deformities from in-utero positioning
• A rapidly enlarging head, a bulging soft spot, or sleepy feeding — signs of hydrocephalus
• Trouble breathing, swallowing, or a weak cry — possible signs of symptomatic Chiari II malformation

As your child grows

• Motor function: Children with lower (sacral) lesions often walk independently; children with mid-lumbar lesions may walk with braces and crutches; children with high-lumbar or thoracic lesions typically use a wheelchair for distance
• Bladder and bowel: Nearly all children need a bladder management program (usually clean intermittent catheterization) and a bowel routine to stay continent and protect the kidneys
• Hydrocephalus: 80-90% of children need a shunt or an endoscopic third ventriculostomy to drain spinal fluid
• Skin: Because sensation is reduced, pressure sores on the feet, buttocks, and hips are a lifelong risk
• Tethered spinal cord: Scar tissue at the repair site can pull on the cord as the child grows, causing new weakness, pain, or bladder changes — sometimes years later

Warning signs parents should know

• A head that is suddenly growing faster, a bulging soft spot, vomiting, sleepiness, or new eye-crossing — possible shunt malfunction
• New snoring, breath-holding spells, choking with feeds, or a weak or high-pitched cry — possible symptomatic Chiari II
• New back pain, leg weakness, changes in walking, or loss of previously achieved bladder control — possible tethered cord
• Sudden fever with a child who has a shunt — call your team the same day

How Is It Diagnosed?

Before birth

Most cases of myelomeningocele in the United States are now diagnosed prenatally, which is what makes fetal surgery even possible. The workup usually starts with one of two things:

• A routine second-trimester anatomy ultrasound (around 18-22 weeks) showing the open defect, a "lemon sign" shape of the skull, and a "banana sign" appearance of the cerebellum — classic signs of the Chiari II malformation
• An elevated maternal serum alpha-fetoprotein (AFP) on routine first- or second-trimester screening

Once the diagnosis is suspected, families are referred to a fetal care center for a targeted high-resolution ultrasound, fetal MRI, and fetal echocardiogram. The fetal MRI confirms the level of the lesion, measures the ventricles, grades the Chiari II, and rules out other brain malformations. An amniocentesis with chromosome testing (karyotype and microarray) is offered because about 3-5% of fetuses with spina bifida have an additional chromosomal abnormality.

With that information, the family meets a multidisciplinary counseling team — maternal-fetal medicine, pediatric neurosurgery, neonatology, and social work — to talk through the three possible paths: fetal surgery, planned cesarean delivery with postnatal closure, or, in some cases, pregnancy termination. The choice is deeply personal and depends on the lesion level, ventricle size, gestational age, maternal factors, and the family's values.

At and after birth

When a baby is born with myelomeningocele, the defect is covered with a sterile, saline-soaked dressing, and the baby is positioned on her side or belly to protect the sac. A head ultrasound measures the ventricles, and an MRI of the brain and spine is obtained within the first few days to plan surgery and to look for associated issues like a syrinx (fluid cavity in the spinal cord) or tethered cord anatomy. A renal ultrasound and urodynamic testing set the baseline for the urologic team.

Types of Spina Bifida

"Spina bifida" is an umbrella term that covers a spectrum of problems with how the spine and spinal cord form. Not all of them behave the same way, and it is worth knowing where your or your child's diagnosis fits on that spectrum.

Spina bifida occulta

This is the mildest and most common form. There is a small bony gap in one or more vertebrae, but the spinal cord, nerves, and skin are all intact. It is often discovered incidentally on an X-ray done for another reason and almost always causes no symptoms. A dimple, birthmark, or tuft of hair over the lower back can sometimes be a clue that something deeper is going on (see "closed spinal dysraphism" below) and is worth an ultrasound or MRI in infancy.

Closed spinal dysraphism (occult spinal dysraphism)

These are hidden problems beneath normal-looking skin: tethered spinal cord, lipomyelomeningocele, dermal sinus tract, split cord malformation. The spinal cord is covered but abnormally fixed or connected to other tissues. Children may have subtle signs in infancy (a dimple, hairy patch, skin tag, or fatty lump over the lower spine) and can develop weakness, foot deformities, pain, or bladder problems as they grow. Surgery to untether the cord can stabilize or reverse these symptoms.

Meningocele

In a meningocele, the spinal canal is open and the meninges (the protective membranes) bulge out through the defect, but the spinal cord and nerve roots stay in their normal position. Because the neural tissue itself is not involved, children with true meningoceles typically have normal leg function, normal bladder and bowel function, and normal intelligence. Surgery is primarily to close the skin and membranes.

Myelomeningocele (spina bifida aperta)

This is the most severe form and the one this article focuses on. The spinal cord and nerve roots themselves are exposed at the surface — there is no skin or bone over them — and below the level of the defect the cord has not formed normally. Myelomeningocele is the form that causes paralysis, bladder and bowel problems, Chiari II malformation, and hydrocephalus.

Myeloschisis

Myeloschisis is essentially myelomeningocele without a sac: the exposed, flattened spinal cord lies directly on the skin surface with no dome of fluid around it. It is managed the same way as myelomeningocele but is often associated with a higher risk of infection before closure.

How Is It Treated?

Preventing it in the first place

The single most effective "treatment" for neural tube defects is prevention. Taking 400 micrograms of folic acid every day before conception and through the first trimester reduces the risk of a first-occurrence neural tube defect by about 70%. Women who have already had one affected pregnancy or who take certain anti-seizure medications are advised to take a higher dose (usually 4 milligrams daily). Since the FDA required folic acid fortification of enriched grain products in 1998, the rate of spina bifida in the United States has dropped by about a third — but the prevention story is still not finished, and every pregnancy planner should be on folic acid.

Fetal surgery (prenatal closure)

For eligible families, fetal surgery is now a well-established option. In 2011, the NIH-sponsored Management of Myelomeningocele Study (MOMS) — a randomized trial across three fetal care centers — showed that closing the defect in utero, typically before 26 weeks of gestation, produces dramatically better outcomes than waiting until after birth:

• The need for a ventriculoperitoneal shunt by age 1 dropped from 82% to 40%
• Twice as many children walked independently at 30 months (42% vs. 21%)
• Hindbrain herniation from the Chiari II malformation was reversed or improved in most fetuses
• Motor function was, on average, two spinal levels better than the anatomic level of the lesion

These benefits came with real tradeoffs: fetal surgery increases the risk of preterm delivery, premature rupture of membranes, and uterine dehiscence, and it commits the mother to a cesarean delivery for this and all future pregnancies. Not every family or every fetus qualifies — MOMS eligibility required a lesion between T1 and S1, a normal karyotype, a singleton pregnancy, and several specific maternal factors. Both open fetal surgery (through a hysterotomy) and fetoscopic (keyhole) techniques are now used at specialized fetal care centers, and families considering this path should be evaluated at a high-volume program.

Postnatal closure

For babies who do not undergo fetal surgery, the neural placode (the exposed spinal cord) is covered with a sterile dressing at birth and the baby is taken to the operating room, usually within 24 to 48 hours. Early closure dramatically reduces the risk of meningitis and ventriculitis, which used to be the main cause of early death. In the operating room, your neurosurgeon carefully separates the neural tissue from the surrounding skin, folds it back into a tube, and reconstructs the coverings of the spinal cord (dura), the paraspinal muscles, and finally the skin over the defect.

Managing hydrocephalus and the Chiari II malformation

Even after successful closure, most children with myelomeningocele develop hydrocephalus and need a procedure to drain spinal fluid. The two main options are:

• Ventriculoperitoneal (VP) shunt — a thin tube that diverts spinal fluid from the brain to the abdomen. Shunts are reliable but can clog, break, or get infected over a lifetime; most children will need at least one shunt revision.
• Endoscopic third ventriculostomy with choroid plexus cauterization (ETV/CPC) — a minimally invasive operation that creates a new drainage pathway without leaving hardware behind. It works best in carefully selected infants and avoids lifelong shunt dependence when successful.

Symptomatic Chiari II malformation — with swallowing trouble, breath-holding, or weak cry in infants — is a neurosurgical emergency and may require a posterior fossa decompression. Making sure any existing shunt is working comes first, because most of the time symptoms improve once spinal fluid pressure is normalized.

Tethered cord release

As children grow, scar tissue at the repair site can pull downward on the spinal cord and cause new weakness, pain, scoliosis, or bladder changes. When new symptoms appear, your neurosurgeon may recommend a tethered cord release, a procedure to carefully free the cord from the surrounding tissue. Not every child with a "tethered-looking" MRI needs surgery — decisions are based on actual clinical deterioration.

Lifelong urologic and orthopedic care

Good spina bifida care is as much about the kidneys, the bladder, the hips, the feet, and the spine as it is about the brain. Almost every child with myelomeningocele will need:

• Urology — clean intermittent catheterization starting in infancy, medications to relax an overactive bladder, bladder augmentation surgery for some children, and lifetime kidney monitoring
• Orthopedics — bracing, casting for clubfoot, hip surveillance, and scoliosis monitoring (surgery is sometimes needed for progressive curves)
• Physical and occupational therapy — starting from infancy to build strength, range of motion, and functional independence
• Bowel management programs to achieve social continence
• Neuropsychology for school-age children, because attention and executive function challenges are common

The most important predictor of a good outcome over a lifetime is not any single surgery — it is the continuity of a multidisciplinary spina bifida clinic that follows your child from birth through adolescence and into adulthood.

What Are the Outcomes?

The outlook for children with myelomeningocele has improved dramatically over the last 50 years, and it continues to improve today with earlier diagnosis, fetal surgery, and coordinated lifelong care. Survival, independence, and cognitive outcomes are all much better than most families are told at the initial diagnosis.

Survival

With modern care, about 75-85% of children born with myelomeningocele reach adulthood. Most early deaths are caused by symptomatic Chiari II malformation in infancy or shunt-related complications; the risk is highest in the first years of life and then falls steadily. Lifetime mortality remains higher than in the general population, mostly because of kidney disease, shunt malfunction, and accidents related to insensate skin and mobility.

Results of the MOMS trial

The MOMS trial is the most important randomized evidence we have for any prenatal intervention. The results below compare babies who had fetal surgery before 26 weeks with babies who had standard postnatal closure:

The school-age follow-up of the MOMS trial (MOMS2), published in 2020, showed that the motor and mobility advantages of prenatal surgery persisted into ages 5 to 10 years. Cognitive and adaptive behavior scores were similar between the two groups; for both groups, children who needed a shunt did worse neurodevelopmentally than those who did not, which is why reducing the shunt rate matters so much.

Independence in adulthood

In large long-term cohorts, including the classic Chicago series followed by Robin Bowman and David McLone, roughly 85% of young adults with myelomeningocele are in mainstream education or employment, and many live independently or semi-independently. IQ is in the normal range for most children with well-controlled hydrocephalus, though subtle problems with attention, executive function, and math are common and benefit from school support. Ambulation depends heavily on lesion level: most children with sacral lesions walk, about half with lumbar lesions walk with bracing, and most with thoracic lesions use a wheelchair for community distances.

The thread running through every part of this story is the same: where and by whom your child is cared for matters more than almost any other decision. A family that walks into a multidisciplinary spina bifida clinic — pediatric neurosurgery, urology, orthopedics, rehab, nutrition, and social work all in one place — gets better outcomes, fewer emergencies, and a smoother transition to adult care than a family navigating ten separate offices alone.

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