Neurosurgery Department, UF College of Medicine
Spina Bifida
The University of Florida has a dedicated spina bifida clinic. Please contact our office for more information.
The spina bifida clinic operates under the guidance of:
About Spina Bifida
Neural tube defects include the conditions of anencephaly, encephalocele, and spina bifida. Spina bifida, also known as spinal dysraphism, is a general term encompassing a large group of congenital spinal anomalies, which are the result of failed closure of the neural tube during fetal development. The defect of spinal dysraphism occurs in the first 8.5 weeks of fetal life.
Despite much research on spina bifida we still do not know what causes the majority of human cases. Nevertheless, there is substantial evidence supporting a significant protective effect of folic acid (0.4mg/day) when taken by women early in pregnancy.
Spina bifida describes birth defects caused by an incomplete closure of one or more vertebral arches of the spine, resulting in malformations of the spinal cord. The spinal membranes and spinal cord may protrude through the absence of vertebral arches (called a cleft). These malformations fall into three categories: spina bifida occulta, spina bifida cystica (myelomeningocele) and meningocele.
They are also classified as either open or closed. Open types involve a cystic mass containing neural tissue along the spinal axis. Closed types are more difficult to diagnose because overlying intact skin masks the underlying abnormality.
Spina bifida occulta ("hidden")
This is a mild form of spina bifida. There is no opening on the back, but the outer part of some of the vertebrae are not completely closed. The split in the vertebrae is so small that the spinal cord does not protrude. The skin at the site of the lesion may be normal, or it may have some hairs growing from it; there may be a dimple in the skin, or a birthmark. People with this form may have incontinence, slight ambulatory problems, and slight loss of sensation.
Spina bifida cystica (myelomeningocele)
In this form, the meningeal membranes that cover the spinal cord and part of the spinal cord protrude through a cleft, forming a sac or cyst, which are clearly visible on the skin. The opening is surgically repaired, shortly after birth. The sac or cyst not only contains tissue and cerebrospinal fluid but also nerves and part of the spinal cord. The spinal cord usually damaged at that level. As a result, there is always some degree of paralysis and loss of sensation below the damaged vertebrae. The amount of disability depends very much on where the spina bifida is and the amount of nerve damage involved. Many children and adults with this condition experience problems with bowel and bladder control. In approximately 90% of the people with myelomeningocele, hydrocephalus, extra fluid in the ventricles of the brain, will also occur. Lipomyelomeningoceles are more extensive lesions and represent a combination of a splayed spinal cord fused with a lipomatous mass, which in turn fuses with the subcutaneous adipose tissue.
Meningocele
In this, the least common form, the outer part of some of the vertebrae are split and the meninges are damaged and pushed out through the opening, appearing as a sac or cyst, which contains both the meninges and cerebrospinal fluid. The nerves are not usually badly damaged and are able to function, therefore there is often little disability present. There are usually no long-term problems, although problems can arise. The defect is usually surgically closed soon after birth.
Other Terms associated with Spina Bifida: |
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| Diastematomyelia refers to a complete or partial clefting of the spinal cord |
Tethered spinal cord: refers to a tethered spinal cord which causes it to end below its normal anatomic level. |
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Hydromyelia: refers to an abnormal dilatation of the central canal lined by ependyma. |
Dermal sinus tract: refers to a long, thin, epithelium-lined sinus that extends from the skin surface to the spinal canal. |
Symptoms
After birth, infants need to be examined closely for any sign of spinal bifida. With open type defects, a cystic mass will be seen along the spine. Closed defects are more difficult to detect, however there may be a sacral dimple, a sinus tract, or a hairy patch.
Spina bifida results in varying degrees of paralysis, absence of skin sensation, incontinence, and spine and limb problems depending on the severity and location of the lesion damage on the spine. In very rare cases, cognitive problems also result.
Diagnosis
Fetal ultrasonography is increasingly used as a primary screening tool for NTDs, at about 18 weeks' gestational age, thus the diagnosis is often made in-utero.
Neural tube defects can also be detected during pregnancy by AFP (alpha feto-protien) screening.
Choosing the most appropriate imaging technology for imaging congenital malformation of the spine depends on many factors. MRI is the imaging modality of choice to evaluate the spinal anatomy. CT scans can also be performed, however they expose the infant to radiation.
In myelocele or myelomeningocele, detailed imaging prior to closure is usually not required, but after repair or spontaneous reepithelialization, imaging may be performed to find any associated pathology.
Treatment
Most babies born with the condition will need surgeries to correct spinal, foot or leg problems. During the operation to repair open defects, the spinal cord and its nerve roots are put into place and covered with skin. Many will need ventriculo-peritoneal shunt surgery to drain fluid from the brain.
Tethered cord is a common problem associated with spina bifida. Almost all myelomeningocele patients have tethered cord, caused by the spinal cord damage when it is repaired by surgery soon after birth. Progressive symptoms of worsening leg pain, weakness, or bowel-bladder problems are typically treated with de-tethering surgery and scar removal.
Some medical center are now experimenting and evaluating the efficacy of in-utero surgery to correct the spina bifida lesion. The in-utero surgery occurs in the womb and before birth.
Prevention
Research has shown that folic acid can help prevent spina bifida. It is recommended that all women of childbearing years as well as those women planning to become pregnant should take at least 0.4 mg of folic acid from at least one month before conception, and at least 1 mg of folic acid during at least the first three months of pregnancy.
View publications by Dr. David Pincus
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