A pediatric neurosurgeon’s perspective about the enigmatic condition known as spina bifida
Spina bifida is unusual in that it is both rare and the most common permanently disabling birth defect. More than 166,000 individuals in the United States have the disorder. Chief of Pediatric Neurosurgery at Masonic Chidren's Hospital Daniel Guillaume, MD, MS, helps raise awareness about this enigmatic condition – its origins, its types, its consequences, and its treatment.
What is spina bifida?
It’s a type of defect that occurs when a baby’s neural tube fails to develop or close properly, according to Guillaume. “The neural tube runs from the head down the back and typically closes at the end of the first month of pregnancy,” he said. “Inside that tube, the brain and spine develop. Spina bifida occurs when the tube doesn't completely close. It usually happens toward the lower back, but it can happen anywhere along the spine.”
What causes it?
“We don’t really know all the things that cause it,” said Guillaume (pictured here). “Low folic acid is a risk factor, but that doesn’t mean that taking folic acid will always prevent it – it just decreases your baby’s chances of getting it. And the time to take folic acid is well before you get pregnant.” Obesity and diabetes are also risk factors for spina bifida, as is fever or hypothermia during the first weeks of pregnancy, he added.
There may also be a genetic component. Research shows the likelihood of having a second baby with spina bifida is about three percent, according to the Spina Bifida Association (SBA). “It’s important to know that neural tube defects like spina bifida are not caused by the actions of the parents,” the Association notes on its website. “It is recommended that adults with spina bifida and couples who already have a child with the condition talk with their OB-GYN or genetic counselor about their risk factors and ways to reduce that risk.”
Does spina bifida always occur in the same way?
No. According to the SBA, the three primary types are:
- Spina bifida occulta
Often called “hidden spina bifida” because about 15 percent of healthy people have it and do not know it, spina bifida occulta usually does not cause harm and has no visible signs. The spinal cord and nerves are usually fine. In this population, however, tethered spinal cord can be an insidious complication that requires investigation by a neurosurgeon - Meningocele
Meningocele causes part of the spinal cord to come through the spine like a sac that is pushed out through the skin. Nerve fluid is in the sac, and there is usually no nerve damage. Individuals with this condition may have minor disabilities. - Myelomeningocele (meningomyelocele)
This is the most severe form and what we typically think of as spina bifida, according to Guillaume. It happens when parts of the spinal cord and nerves come through the open part of the spine. It causes nerve damage and other disabilities. Most children with this condition also have hydrocephalus – too much cerebrospinal fluid on their brains – because the fluid is unable to drain like it should.
How is the condition diagnosed?
“In this country, it’s usually diagnosed during the second trimester of pregnancy,” said Guillaume. “A blood test given to the mother screens for high levels of alpha fetoprotein [AFP], which is produced by the baby’s nervous system. In babies with spina bifida, that protein can leak into the amniotic fluid and from there to the mother’s blood. If we see a high level of AFP, it may indicate spina bifida, which drives further testing.”
What problems does spina bifida cause?
It creates a chain reaction, noted Guillaume. “Keep in mind that this happens before the brain develops,” he said. “The neural tube is meant to be closed and when it isn’t, the back of the head and the brain develop abnormally. The brain can slide down into the spinal canal causing what’s known as a Chiari II malformation. If it’s not treated in utero, about 80 to 85 percent of these kids develop hydrocephalus and multiple brain-related problems. They can also have physical problems such as bladder and bowel issues.”
How is spina bifida treated?
Treatment for spina bifida depends on the severity of the condition. If myelomeningocele is diagnosed, the treatment is to close the defect and put everything back as close to the way it’s supposed to be as possible, according to Guillaume. “The procedure is called myelomeningocele closure and it can be done in utero or after delivery,” he noted. During the procedure, a Fetal Medicine specialist performs a mini caesarean section on the mother to expose the baby’s back. The neurosurgeon then returns the spinal cord to where it belongs, closes the dura, and the muscle and soft tissues of the skin. The Fetal Medicine specialist ends the procedure by closing the uterus. “We liken it to ‘closing the pages of the book,’” said Guillaume. The surgery is done around halfway through the pregnancy.
The procedure can improve outcomes for the infant. “You stop the chain reaction earlier,” said Guillaume. “It lowers the risk of developing the Chiari II malformation and significantly lowers the risk of hydrocephalus. The brain also develops more normally.”
Where is spina bifida treated?
Spina bifida is treated primarily at hospitals for children by a multispecialty team that includes pediatric neurosurgeons. “We have significant experience caring for these patients at Masonic Children’s Hospital – spina bifida is one of the most common conditions that we treat,” said Guillaume. “We are one of the few neurosurgery groups that cares for these patients throughout their lives.”
Interested in spina bifida research? Learn more.
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