Spina Bifida (also called myelodysplasia or neural tube defect)
Spina bifida occurs in the first month after fertilization as the result of a failure of part of the spine to fully form. Spina bifida is part of a group of birth defects called neural tube defects. Normally, the neural tube forms early in the pregnancy and closes by the 28th day after conception. The embryonic cells that form the neural tube, and eventually form the spine, do not fully develop. The spinal cord therefore lacks a bony covering due to defects in the vertebrae bone formation. The nervous system tissue of the spinal cord can also be affected. This can occur anywhere along the length of the spinal column. Those that occur in the spine are categorized under the term "spina bifida", and 80% of these are located in the lumbar and sacral areas (lower back) of the spine. Spina bifida occurs in various forms of severity. The three forms of spina bifida range from very minor to severe:
- Spina Bifida Occulta (SPI-nuh. BIF-id-uh. oh-KULT-uh): A small hairy patch, or a soft skin colored mass called a lipoma, or a small dimple in the skin may overlie the affected bony malformation and be the only external sign of spina bifida occulta.
- Meningocele (muh-NING-go-SEEL): This type of defect in the vertebrae is very small and fluid-filled meninges protrude through the opening in the bone. The spinal cord and nerves are intact.
- Myelomeningocele or meningomyelocele: This is the most common type of spina bifida and it is typically more severe in nature. Some of the spinal cord's neural tissue is exposed through a bony defect in one or more vertebrae. There is an absence of muscle and skin that would normally protect the spinal cord, and nerve damage is permanent, resulting in varying symptoms.
The cause of spina bifida remains unknown. Folic acid deficiency has been implicated in causing neural tube defects. Maternal nutrition, exposure to radiation, drugs and chemicals as well as a genetic predisposition may be other causes of neural tube defects. If mothers took 400 micrograms daily of Vitamin B folic acid at least 1 month before and during pregnancy, 50-70% of neural tube defects could be prevented, even among mothers who have previously had a child with a neural tube defect.
Spina bifida is the most common of the severe birth defects, occurring in one of every 1500-2000 live births. The most severe variant, myelomeningocele, occurs in one of every 4000 live births. Our program has been tracking spina bifida without anencephalus - a condition that has a defect in the formation of the skull and the brain - among live births in select counties since 2005 and are gradually expanding statewide.
- Using data from births to Hennepin and Ramsey county residents between 2009-2013, we found that 2.5 babies were born with spina bifida without anencephalus per 10,000 births.
- Using this data, we estimate about 17 babies are born with spina bifida without anencephalus every year in Minnesota.
Parental education and support are essential, and local, regional and national organizations may be very helpful.