Spina Bifida (Myelomeningocele)

The most common and serious form of spina bifida is called myelomeningocele (MMC), in which part of the spinal cord
and surrounding nerves push through the open bones (vertebrae) in the spine and protrude from the fetus’ back. Usually,
the exposed spinal cord and nerves are contained in a sac that is exposed to amniotic fluid. Continuous bathing of the fragile
developing spinal cord in amniotic fluid over the course of gestation is thought to result in progressive neurologic injury.
Spina bifida occurs in 3.4 per 10,000 live births in the United States and is the most common central nervous system
birth defect. Between 1,400 and 1,500 babies are born with spina bifida in the U.S. each year. Liveborn infants with
MMC have a mortality rate of approximately 10 percent.
The MMC lesion can occur at any level on the developing spine, but most are found in the lumbo-sacral region.
Depending on the lesion’s location, MMC may cause bladder and bowel problems; sexual dysfunction; weakness and loss
of sensation below the defect; orthopaedic malformations such as club feet or problems of the knees or hips; and inability
to move the lower legs (paralysis). Generally, the higher the defect is located on the spine, the more severe the complications.
In many cases, the brain develops a Chiari II malformation, in which the hindbrain herniates or descends into the upper
portion of the spinal canal in the neck. This herniation of the hindbrain blocks the circulation of cerebrospinal fluid,
causing hydrocephalus (accumulation of fluid in the brain), which can injure the developing brain