Spina bifida

[Sarah]

A congenital malformation in which the spinal column is cleftat its lower portion, and the membranes of the spinal cord project asan elastic swelling from the gap thus formed.

[Jessica]

Spina bifida is defective closure of the vertebral column. Although the cause is not known, low folate levels during pregnancy increase risk. Some children are asymptomatic, and others have severe neurologic dysfunction below the lesion. Open spina bifida can be diagnosed prenatally by ultrasonography or suggested by elevated alpha-fetoprotein levels in maternal serum and amniotic fluid. After birth, a lesion is typically visible on the back. Treatment is usually surgical.
Spina bifida is one of the most serious neural tube defects compatible with prolonged life. This defect is one of the more common congenital anomalies overall, with an incidence in the US of about 1/1500. It is most common in the lower thoracic, lumbar, or sacral region and usually extends for 3 to 6 vertebral segments. Severity ranges from occult, in which there are no apparent anomalies, to protruding sacs (spina bifida cystica), to a completely open spine (rachischisis) with severe neurologic disability and death.
In occult spinal dysraphism (OSD), anomalies of the skin overlying the lower back (typically in the lumbosacral area) occur; these include sinus tracts that have no visible bottom, are above the lower sacral area, or are not in the midline; hyperpigmented areas; asymmetry of the gluteal cleft with the upper margin deviated to one side; and tufts of hair. These children often have anomalies in the underlying portion of the spinal cord, such as lipomas and tethering (in which the cord has an abnormal attachment—see figure Forms of spina bifida).
In spina bifida cystica, the protruding sac can contain meninges (meningocele), spinal cord (myelocele), or both (myelomeningocele). In a myelomeningocele, the sac usually consists of meninges with a central neural plaque. If not well covered with skin, the sac can easily rupture, increasing the risk of meningitis.
Hydrocephalus is common because many children have a Chiari II type malformation.
Syringomyelia (a dilation of the normally small fluid-filled central canal of the spinal cord) and other congenital anomalies and soft-tissue masses around the spinal cord may be present.