page_title: Spina bifida
section_title: Myelomeningocele
hierarchical_section_title: Spina bifida / Types / Myelomeningocele
caption_attribution_description: English: A lumbar myelomeningocele
context_page_description: Spina bifida is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, meningocele and myelomeningocele. The most common location is the lower back, but in rare cases it may be in the middle back or neck. Occulta has no or only mild signs, which may include a hairy patch, dimple, dark spot or swelling on the back at the site of the gap in the spine. Meningocele typically causes mild problems, with a sac of fluid present at the gap in the spine. Myelomeningocele, also known as open spina bifida, is the most severe form. Problems associated with this form include poor ability to walk, impaired bladder or bowel control, accumulation of fluid in the brain, a tethered spinal cord and latex allergy. Learning problems are relatively uncommon.
  Spina bifida is believed to be due to a combination of genetic and environmental factors. After having one child with the condition, or if one of the parents has the condition, there is a 4% chance that the next child will also be affected.
context_section_description: Myelomeningocele (MMC), 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 individuals with myelomeningocele, the unfused portion of the spinal column allows the spinal cord to protrude through an opening. Myelomeningocele occurs in the third week of embryonic development, during neural tube pore closure. MMC is a failure of this to occur completely. The meningeal membranes that cover the spinal cord also protrude through the opening, forming a sac enclosing the spinal elements, such as meninges, cerebrospinal fluid, and parts of the spinal cord and nerve roots. Myelomeningocele is also associated with Arnold–Chiari malformation, necessitating a VP shunt placement.
  Toxins and conditions associated with MMC formation include: calcium-channel blockers, carbamazepine, cytochalasins, hyperthermia, and valproic acid.
caption: A lumbar myelomeningocele
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