Meningocele repair

Definition

A meningocele repair is a surgical procedure performed to repair an abnormal opening in the spinal column (called spina bifida) by draining excess fluid and closing the opening.

Purpose

The surgery is necessary to close this abnormal opening to decrease the risk of infection and protect the integrity of the spinal column and the tissue inside.

Demographics

According to the Spina Bifida Association of America, spina bifida is both the most common neural tube defect and the most common birth defect resulting in permanent disability. It is estimated that about 40% of Americans have spina bifida occulta. However, some people who have it may have no symptoms and may therefore be unaware of their condition, so the percentage is an approximation. Meningocele and myelomeningocele are noticeable at birth and are paired together as spina bifida manifesta. Spina bifida manifesta occurs in about one in 1,000 births, with 4–5% being meningocele and 95–96% being myelomeningocele.

Description

The term meningocele may be used to refer to more than one condition. Spina bifida is a neural tube birth defect involving an abnormal opening in the spine. It occurs when the fetus's spine does not close properly during the first month of fetal development. In spina bifida occulta an opening in the spinal bones exists, but the neural tissue and membrane covering the spine (the meninges) are not exposed. Because there is no opening, the defect may appear as a dimple, or depression, at the base of the spine (the sacrum). Another sign of spina bifida occulta is the presence of tufts of hair at the sacrum. It is possible that while there is no opening, vertebrae are missing and there is damage to nerve tissue.

A meningocele is a sac protruding from the spinal column, which contains some of the spinal fluid and meninges. The sac may be covered with skin or with the meninges, and does not contain neural tissue. It may be located near the brain or along the spinal column. Hydrocephalus is rarely present, and the neurological examination may be normal. Because the neural tissue remains intact, it can be repaired by the experienced neurosurgeon, with excellent results.

A myelomeningocele is the most severe type of spina bifida because the spinal cord has herniated into the protruding sac. Neural tissue and nerves may be exposed. About 80% of myelomeningoceles occur at the lower back, where the lumbar and sacral regions join. Some people refer to myelomeningocele as spina bifida. Because of the exposed neural tissue, significant symptoms may be present. These symptoms may include:

• muscle weakness or paralysis in the hips and lower limbs
• no sensation in the part of the body below the defect
• lack of bowel and bladder function
• fluid build-up in the brain, known as hydrocephalus

Because of the risk of neural tissue damage, swelling, and infection into the spinal fluid and brain with an opening in the spinal column, surgery to repair the meningocele or myelomeningocele is usually done within 24 hours of birth. However, although the opening is closed, whatever damage has already been done to the neural tissue is permanent. If hydrocephalus is developing, the meningocele repair may be done first. Then, a few days later, a shunt can be inserted to resolve the hydrocephalus. If the hydrocephalus is present at birth, the two surgeries may be done at the same time to decrease the risks associated with increasing pressure on the brain. To prevent drying of the sac, it may be kept moist with sterile dressings until surgery is begun. Once the anesthesia has put the baby to sleep and the surgery is pain-free, a surgical incision is made into the sac. Excess fluid is drained, and the meninges is wrapped around the spine to protect it. The opening is then closed with sutures.

Diagnosis/Preparation

If an individual has spina bifida occulta, with no outward signs of a neural tube defect and no symptoms, the condition may go undetected. The protruding sacs associated with meningocele and myelomeningocele are quite noticeable at birth. To understand the extent of the defect x rays, ultrasound, computed tomography (CT) scans, or magnetic resonance imaging (MRI) of the spine may be taken.

Spina bifida may be diagnosed while the mother is still pregnant, through prenatal screening. If spina bifida is indicated, a blood test will show an elevated alpha fetoprotein. However, elevated levels can be present without spina bifida, so further testing should be done if the test is positive. There is an elevated alpha fetoprotein level in about 85% of women with a fetus with spina bifida. An ultrasound can reliable reveal the spinal structure of the fetus. An amniocentesis may be done to check for chromosomal abnormalities. In amniocentesis, a long syringe is used to draw amniotic fluid out from the uterus through the mother's abdomen. Because the protruding sac of the meningocele and myelomeningocele can look the same on the outside, it is important to have a clear diagnosis, as the anticipated outcome of the two conditions is very different.

Aftercare

The infant will first spend some time in the recovery room , and then be transferred to an intensive care unit . The infant will be monitored for signs of excess bleeding and infection. Temperature will be closely monitored. Antibiotics will be given to decrease the risk of infection, and the infant will be positioned to lie flat on the stomach to avoid pressure on the surgical wound. Extreme care is taken to keep the wound clean of urine and stool.

Risks

Surgical risks include infection and bleeding. Anesthesia risks include a reaction to the medications used, including difficulty breathing. During meningocele and myelomeningocele repair, there are additional risks of damage to the spinal column and infection of the spinal fluid surrounding the spine and brain. Damage to the neural tissue could result in paralysis, or loss of nerve function (for example, loss of bowel and bladder control). There may also be an increased risk of an urinary tract infection. An infection of the meninges is called meningitis. However, further damage would be expected if surgery were not done, and serious infection would be likely. As in all surgery, one must weigh the potential risks against the expected benefits.

Normal results

Results depend greatly on the extent of involvement of exposed neural tissue and the condition of the infant prior to surgery. A meningocele repair can have excellent results, as neural tissue does not extend into the protruding sac. In myelomeningocele, the amount of exposed neural tissue will determine the extent of lower limb weakness, or paralysis. The infant will usually spend a few weeks in the hospital after surgery before being able to be discharged home. As the child grows, it may be necessary to use braces, crutches, or a wheelchair for mobility. If surgery for hydrocephalus is successful, the prognosis is better. Children with a repaired myelomeningocele may be able to go to school, but will benefit from special education and associated services. There may be varying degrees of learning problems, and difficulties with the child's attention span. An effective bowel and bladder-training program can help make attending school easier. Because of muscle weakness or paralysis, a child with spina bifida will need physical therapy and may require future surgeries.

Morbidity and mortality rates

With current medical and surgical treatments, about 85% of infants survive, and about 50% will be able to walk. Bowel and bladder disorders contribute significantly to morbidity and mortality in those with spina bifida who survive past the age of two years.

Alternatives

There is no alternative to surgical repair. Risk of infection and damage to the spine and brain is high with an opening to the spine, so surgery is necessary to close the opening and drain the excess fluid that could put pressure on the brain. The Spina Bifida Association of America recommends that all women of childbearing age take 0.4 mg of folic acid daily, as this amount has been shown to decrease the likelihood of neural tube defects. Once a woman is aware of being pregnant, the critical first month of neural tube development has already past, and folic acid cannot cure any damage that has been done.

Resources

books

Senisi, Ellen B. All Kinds of Friends, Even Green! Woodbine House, November 2002.

organizations

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue; White Plains, NY. Telephone (914) 428-7100. http://wwwmodimes.org .

National Library of Medicine. http://www.nlm.nih.gov .

Spina Bifida Association of America. 4590 MacArthur Boulevard, NW, Suite 250; Washington, DC 20007-4226. Telephone (800) 621-3141, (202)944-3285. sbaa@sbaa.org. http://www.sbaa.org .

Esther Csapo Rastegari, R.N., B.S.N., Ed.M.

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

Surgery on the spine is a very delicate procedure and needs to be done by a surgeon specializing in pediatric neurosurgery . It is best performed in a hospital with a pediatric intensive care unit available to closely monitor the infant after the surgery.

QUESTIONS TO ASK THE DOCTOR

• What is the extent of the neurological damage?
• Is my child likely to walk?
• What experience do you have with this procedure?
• What complications have your patients experienced with this procedure?
• How long is my child likely to stay in the hospital?