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Myelomeningocele (Spina Bifida)

diagram of Myelomeningocele Click To Enlarge

diagram of Myelomeningocele
Click To Enlarge

What is a myelomeningocele?

Myelomeningocele (spina bifida) results from a failure in the closure of the neural tube along the spine. A portion of the spinal cord protrudes and is not covered by skin, and is usually associated with paralysis of the involved spinal nerves. The malformation occurs very early in pregnancy during the closure of the neural tube (spinal cord). The defect can occur anywhere along the spinal column.

Myelomeningocele occurs in approximately 1 in every 1,000 pregnancies. Taking folic acid before pregnancy has reduced the incidence of this defect.

What testing is recommended during the pregnancy?

Serum AFP (alpha-fetoprotein) testing in conjunction with a second trimester ultrasound detects over 90% of infants affected with a neural tube defect. This simple blood test has been incorporated into standard prenatal testing and acts as a screening tool to alert care providers that there is a potential problem with the baby.

Serial ultrasounds will monitor the baby's progress. These infants are not at higher risk for growth problems. A chromosome analysis is recommended, due to the increased incidence of chromosomal abnormalities.

A fetal MRI may be performed to further evaluate the spine and brain anomalies related to the myelomeningocele. A fetal echocardiogram is only recommended when there is suspicion of a heart defect during a prenatal ultrasound.

Are there special considerations for the delivery?

It is recommended that the delivery of the baby is planned at a hospital that is prepared for high-risk deliveries, has pediatric neurosurgical services, and a neonatal intensive care unit. This will help facilitate coordination between all involved services.

Although the type of delivery remains controversial, there is no clear evidence that having a Cesarean-section delivery will improve the outcome of a baby with a myelomeningocele. We recommend a vaginal delivery, unless there are obstetrical indications for a cesarean delivery.

Is there fetal treatment for myelomeningocele?

There is fetal treatment available for a select group of patients performed during the second trimester. The Management of Myelomenigocele Study (MOMS) trial ended early with positive results published in the New England Journal of Medicine. Although open fetal surgery for myelomeningocele improves outcomes, it is not a cure. The potential benefits must be weighed against the possible risks for mother and baby. To read more about open fetal surgery at the University of Michigan, click here.

What is the postnatal treatment for myelomeningocele?

Standard treatment is to repair the defect after the baby is born. It is recommended that the defect be closed within the first 48 hours to preserve the neural tissue and prevent infection. Once the myelomeningocele has been closed, about 80% of the infants develop hydrocephalus (increased cerebral spinal fluid levels around the brain) and require a ventroperitoneal shunt (a small drainage tube) within a few days.

Are there other health problems that are more common among babies with myelomeningocele?

These children require life-long medical support to address a variety of issues. The location of the myelomeningocele is usually related to the long-term prognosis for these children. Generally speaking, the outcome is usually better for defects lower on the spine.

These children often require lifelong interventions in the neuromuscular, musculoskeletal, urinary, and gastrointestinal systems. Cognitive function is variable, but many children exhibit some degree of learning disability.

Latex allergies are more common with these children as they are exposed to multiple surgical procedures, and urinary catheterizations throughout their lifetime. Multiple exposures may lead to a clinical latex reaction and possibly an anaphylactic reaction during routine care at home. Every effort should be made to remove latex items from the child's environment from birth.

Can this happen again with another pregnancy?

In most cases, myelomeningocele is considered to be a due to multifactorial inheritance with a low recurrence risk of approximately 3-5%. A small portion of cases have been linked to a chromosomal problem, or other underlying etiology. A family history of spina bifida also increases risk. Your doctor and a genetic counselor will discuss the likelihood in your family.

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