Spina Bifida Complications Are Based on Severity of Defect

Spina bifida is a condition in which the neural tube - the part of the fetus that forms the brain and spinal cord - does not completely close. It is the most common neural tube defect in the United States, affecting 1,500 to 2,000 of the more than 4 million babies born in the country each year.

Symptoms of spina bifida vary depending on the severity of the defect, says Bruce A. Kaufman, MD, including the size and location of the malformation, whether or not skin covers it, and which spinal nerves are involved.

Complications of spina bifida can range from minor physical problems to severe physical and mental disabilities. In general, all the nerves located below the malformation are affected. Therefore, the higher the malformation occurs on the back, the greater the amount of nerve damage and loss of muscle function and sensation.

These factors will determine the types of treatment needed for the patient.

Dr. Kaufman stresses that parents need to be very careful about information resources, especially on the Internet. There are some conditions that are very similar in name but not in anatomy or function, so parents must be clear on which type of condition has affected their child. Also, there can be misinformation on some web sites. "They ought to be cautious and make sure they have appropriate information from knowledgeable individuals," he says.

Symptoms Vary by Type
There are four types of spina bifida:

• Occulta is the most common form, in which one or more vertebrae are malformed. The name "occulta," which means "hidden," indicates that the malformation, or opening in the spine, is covered by a layer of skin. This form of spina bifida rarely causes disability or symptoms because it usually does not affect the nervous tissue.
• Closed neural tube defects are a diverse group of spinal defects in which the spinal cord is affected by or attached to a malformation of fat, bone, or membranes. In some patients there are few or no symptoms; in others the malformation causes incomplete paralysis with urinary and bowel dysfunction.
• Meningocele is a condition in which the meninges (the coverings of the spinal cord and spinal canal) protrude from the spinal opening; the malformation may or may not be covered by a layer of skin. Some patients with meningocele have few or no symptoms while others may experience symptoms similar to closed neural tube defects.
• Myelomeningocele is the most severe form of spina bifida, in which the spinal cord is exposed through the opening in the spine, resulting in partial or complete paralysis of the parts of the body below the spinal opening. The paralysis may be so severe that the affected individual is unable to walk and may have urinary and bowel dysfunction.

Causal Factors
The exact causes of spina bifida remain a mystery. Scientists suspect that genetic, nutritional, and environmental factors all play a role. Research studies indicate that insufficient intake of folic acid - a common B vitamin - in the mother's diet is a key factor in causing spina bifida and other neural tube defects. This has led to the recommendation that all women of childbearing age should take folic acid supplements every day. Taking it after becoming pregnant has no effect, cautions Dr. Kaufman.

"We know from population studies that certain ethnic groups more frequently have children born with spina bifida," Dr. Kaufman says. "We know from studies that there can be geographic differences: more cases on one coast than the other. We also know that the incidence has been going down. It may be in relation to dietary supplementation or just general health care. We also know that if you have one child with spina bifida, the chances of having another child with it significantly increase. So clearly there is a genetic component."

Diagnosis
In many cases, spina bifida is diagnosed before birth through maternal screening with blood work or ultrasound evaluation. However, some cases may go unnoticed until after the child is born. Very mild cases, in which there are no symptoms, may never be detected.

The most common screening methods for spina bifida during pregnancy are second trimester maternal serum alpha fetoprotein (MSAFP) screening and fetal ultrasound. The MSAFP screen measures the level of alpha-fetoprotein (AFP), a protein which is made naturally by the fetus and placenta. During pregnancy, a small amount of AFP normally crosses the placenta and enters the mother's bloodstream. But if abnormally high levels of this protein appear in the mother's bloodstream it could indicate that the fetus has a neural tube defect.

The MSAFP screen may be performed alone or as part of a larger, multiple-marker screen. Multiple-marker screens look not only for neural tube defects, but also for other birth defects, including Down syndrome and other chromosomal abnormalities.

Mild cases of spina bifida that are not diagnosed during prenatal testing may be detected by spinal X-rays or magnetic resonance imaging (MRI) after the child is born.

Complications
In addition to loss of sensation and paralysis, another neurological complication associated with spina bifida is Chiari II malformation - a condition that is common in children with myelomeningocele - in which the brainstem and the cerebellum, or rear portion of the brain, are compressed by the skull and protrude into the spinal canal or neck area. This condition can lead to compression of the spinal cord and cause a variety of symptoms including difficulties with feeding, swallowing, and breathing; choking; and arm stiffness.

Most children with myelomeningocele will also develop an abnormal buildup of cerebrospinal fluid within the brain, a condition called hydrocephalus. Cerebrospinal fluid is a clear liquid that surrounds the brain and spinal cord. Hydrocephalus is commonly treated by surgically implanting a shunt (a hollow tube) in the brain to drain the excess fluid into the abdomen.

Because newborns with myelomeningocele have an opening directly into the nervous system (the exposed spinal cord), they are at risk for developing meningitis, an infection in the covering of the brain. Meningitis may cause brain injury and can be life-threatening. The key priorities for treating myelomeningocele are to close the defect, and thus prevent infection from developing through the exposed nerves and tissue. This should occur soon after birth, Dr. Kaufman says.

Children with myelomeningocele are at risk for developing a condition called tethered cord syndrome, in which the spinal cord becomes fastened to the adjacent tissues and scar at the site of the original closure. This can affect the spinal cord, causing loss of function to the muscles, legs, bowel, and bladder. Surgery on the spinal cord to disconnect it from the tissues (called "untethering") might allow the child to regain function and prevent further neurological deterioration.

Children with both myelomeningocele and hydrocephalus may have learning disabilities, including difficulty paying attention, problems with language and reading comprehension, and trouble learning math. "It's not that they can't learn," explains Dr. Kaufman, "but many cannot process information in the same way as other people do."

Some individuals with spina bifida require assistive devices for walking. Children with a defect high on the spine and more extensive paralysis will often require a wheelchair, while those with a defect lower on the spine may be able to use crutches, leg braces, or walkers. "If you've got good function across your knees, you're probably going to be able to ambulate yourself independently; that is, with braces or crutches," notes Dr. Kaufman.

Some children born with spina bifida will need surgeries later in life to manage problems with their feet, hips, or spine. Individuals with hydrocephalus generally will require additional surgeries to replace shunts, which can be outgrown or become clogged.

Treatment for paralysis and bladder and bowel problems typically begins soon after birth, and may include special exercises for the legs and feet to help prepare the child for walking with braces or crutches when he or she is older.

Additional problems such as latex allergies, skin problems, gastrointestinal conditions, and depression may occur as children with spina bifida get older.

Prevention
Folic acid, also called folate, is an important vitamin in the development of a healthy fetus. Recent studies have shown that by adding folic acid to their diets, women of childbearing age significantly reduce the risk of having a child with a neural tube defect such as spina bifida.

Dr. Kaufman says recent studies showed a 72% reduction in the risk of having spinal defect when the mothers took folic acid supplements as compared to those who did not.

All women of childbearing age are encouraged to consume 400 micrograms of folic acid daily. Foods high in folic acid include dark green vegetables, egg yolks, and some fruits. Many foods - such as some breakfast cereals, enriched breads, flours, pastas, rice, and other grain products - are now fortified with folic acid, and many multivitamins also contain the recommended dosage of folic acid.

The prognosis for children with spina bifida depends on the number and severity of abnormalities and associated complications. Most children with spina bifida can walk, usually with assistive devices, and can lead relatively active lives. They generally have normal intelligence; but if learning problems develop, early educational intervention is helpful.

Dr. Kaufman says that one of the goals of those who treat spina bifida patients is to improve their functionality and independence. Studies show that kids who are involved in summer camps where they have the opportunity to engage in independent activities become more independent as they grow older.

This article includes information from the National Institute of Neurological Disorders and Stroke and the Spina Bifida Association of Wisconsin.

Bruce A. Kaufman, MD, is a Medical College of Wisconsin Professor of Neurosurgery and Chief of Pediatric Neurosurgery. He is also the Medical Director of Neurosurgery at Children's Hospital of Wisconsin and practices at the Children's Hospital Neuroscience Center.

For more information on this topic, see the HealthLink article From Child to Adult: Meeting the Needs of Spina Bifida Patients.