Brent Cornell

    
Closure of the neural tube does not occur simultaneously along the entire length of the embryo

• The area where the brain forms is well advanced over the caudal (tail) region, where closure occurs more slowly

Spina bifida is a birth defect resulting in the incomplete closure of the neural tube (and associated vertebrae)

• It is most commonly seen in the lumbar and sacral areas, as these are the regions where closure is slowest
• The vertebral processes do not fuse, leaving the spinal cord nerves exposed and prone to damage

Comparison of Vertebrae

The severity of the condition can vary from mild to severe depending on the consequence of the incomplete closure

• In cases of spina bifida occulta, the splits in the vertebrae are so small that the spinal cord does not protrude
• In spina bifida cystica, a meningeal cyst forms (meningocele) which may include the spinal elements (myelomeningocele)
• In the more severe cases, patients may typically suffer some degree of paralysis, as well as bowel and bladder dysfunction

Spina bifida is believed to be caused by a combination of genetic and environmental factors

• The average worldwide incidence of the condition is ~1 in 1,000 births, however marked geographic variation occurs
• Not having enough folate in the diet during pregnancy is believed to play a significant role in causing spina bifida

Types of Spina Bifida