Spina bifida :is a birth defect in which the neural tube, a layer of cells that ultimately develops into the brain and spinal cord, fails to close completely during the first few weeks of embryonic development which a results in incomplete closure of bones of the spinal column around the developing nerves of the spinal cord. Part of the spinal cord may stick out through an opening in the spine, leading to permanent nerve damage. Because spina bifida is caused by abnormalities of the neural tube, it is classified as a neural tube defect.
Three main types of Spina Bifida:
Spina bifida occulta:
This is the mildest form of spina bifida. In which the outer part of some of the vertebrae is not completely closed and these splits in the vertebrae are 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 hair growth or a dimple in the skin, or a birthmark. Unlike most other types of neural tube defects
Also called meningeal cyst is the least common form of spina bifida. In this form, a single developmental defect allows the meninges to herniate between the vertebrae. As the nervous system remains undamaged, individuals with meningocele are unlikely to suffer long-term health problems, Myelomeningocele. Myelomeningocele also known as meningomyelocele, is the type of spina bifida that often results in the most severe complications and affects the meninges and nerves. In myelomeningocele, the unfused portion of the spinal column allows the spinal cord to protrude through an opening. The meningeal membranes that cover the spinal cord also protrude through the opening, forming a sac enclosing the spinal elements
The most common location is the lower back, but in rare cases it may be the middle back or neck.
Spina bifida with myelocele is the most severe form of myelomeningocele. In this type, the involved area is represented by a flattened, plate-like mass of nervous tissue with no overlying membrane. The exposure of these nerves and tissues make the baby more prone to life-threatening infections such as meningitis.
The protruding portion of the spinal cord and the nerves that originate at that level of the cord are damaged or not properly developed. As a result, there is usually some degree of paralysis and loss of sensation below the level of the spinal cord defect. Thus, the more cranial the level of the defect, the more severe the associated nerve dysfunction and resultant paralysis may be.