Spina bifida is a common term that may describe an incomplete closure of the spinal column or the neural tube. There are three types of spina bifida: spina bifida occulta, spina bifida with meningocele, and spina bifida with myelomeningocele. In addition to this there are a group of disorders where the skin is closed but the underlying spinal cord has an abnormality. These disorders are called occult spinal dysraphism (OSD) and involve a different problem with embryology.
- Spina bifida occulta (SBO) is a very common disorder where the back of the spinal canal is not completely closed and has no clinical concerns and for which treatment isn’t necessary. They are other groups of conditions that are sometimes under this category that we have included in a separate category called occult spinal dysraphisms (OSD).
- Spina bifida with meningocele (SBM) is a condition where the covering of the spinal cord protrudes or pouches through the spinal bones. This pouch contains spinal fluid and is usually associated with minor physical impairments or no physical impairments at all.
- Spina bifida with myelomeningocele (SBMM) is similar to a meningocele but the sac of fluid also contains parts of the spinal cord and nerve roots. This is the most severe form of spina bifida and may be associated with other neurological complications such as hydrocephalus, syringomyelia, and Chiari type II malformations. The majority of children will have bowel and bladder trouble, difficulty with walking, spinal problems, and may have breathing or swallowing difficulties. To learn more about syringomyelia, hydrocephalus and Chiari visit the write-ups about them in this section of the book.
What causes spina bifida?
The exact cause of spina bifida is unknown but environmental and genetic factors may play a role. Some studies show that low levels of folic acid in the mother during pregnancy may lead to an increased risk for the condition.
How is spina bifida diagnosed?
SBM and SBMM are usually diagnosed on a prenatal ultrasound or fetal MRI. A screening blood test done on pregnant mothers may also show a high level of maternal alpha fetal protein (AFP). Occasionally no abnormality is recognized until birth, in which case it is diagnosed by physical exam.
SBO can be a more difficult diagnosis. Often an ultrasound or MRI of the spine are used to detect the underlying SBO. A thorough history and physical examine is necessary to determine if the SBO is symptomatic or not. Neurosurgeons may order a test called urodynamics to determine if the bladder function is being affected by the condition.
Treatment of spina bifida
Treatment of spina bifida varies greatly depending on the type. SBMM may require relatively urgent surgery at birth in order to place the spinal cord back into the spinal canal with adequate layers of covering. If the pouch is leaking fluid at birth then it will be covered with a sterile dressing and the initial operation to close the back will usually occur a very short time after birth. If the pouch is not leaking fluid, then the surgery will usually occur within 48 hours after delivery.
A baby with SBMM may also have a shunt inserted at the same time as the closure of the back if they have significant hydrocephalus. If the hydrocephalus is mild to moderate, then the baby will be watched closely for signs of increasing hydrocephalus over the next several days or even weeks. Other surgeries may be required to treat a symptomatic Chiari II malformation. Bowel, bladder and orthopedic issues usually occur later in life. Please see the sections on Chiari malformation and hydrocephalus for information on these conditions.
Treatment of a baby with SBM again depends on if the sac is leaking fluid or not. If the sac is leaking fluid then the surgery will occur shortly after birth. If the sac is skin covered, and thus well protected and not leaking fluid, then the surgery may be delayed for hours or even weeks after birth depending on the size of the pouch. Babies with SBM will rarely require other surgeries such as the insertion of a shunt or a Chiari II malformation operation.