Spina bifida

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  • Neural tube defects that are more common in females and can be split into 3 types
    • primary neural tube closure defects
      • anencephaly
        • elevated alpha-fetoprotein
        • more common in females
      • craniorachischisis
      • myelomeningocele
        • most common in lumbosacral lesions; associated with the Chiari type II malformation and hydrocephalus
    • primary axial mesodermal defects
      • encephalocele
      • meningocele
      • split cord (high)
        • associated with cutaneous stigmata of hypertrichosis over a dermal sinus tract and capillary hemangioma
        • other symptoms: myelomeningocele, urinary tract infections
        • other anomalies of the brain or spine are common (e.g. low lying conus, thickened filum
        • treatment: surgical with goal of eliminating the bony septum in between the two cords
    • tail bud defects
      • spina bifida occulta
        • cord may appear normal but often shows a distended central canal (hydromyelia), diastematomyelia, or cord tethering all of which occur at the lower lumbar or sacral levels
        • often indicated by overlying tufts of hairy skin or lipomatous skin tags; may also be associated with sacral, anorectal, and urogenital defects
      • split cord (low)
      • hydromyelia
        • development of the neural tube and axial skeleton
          • induction of the neural plate from midline ectoderm occurs at 16 days after ovulation
          • 18-20 days after ovulation, there is a gradual elevation of the lateral edges of the plate to form the neural folds and deepening of the longitudinal neural groove; midline mesodermal tissue gives rise to both the centrally placed notochord and lateral somites
    • at 22 days, the neural folds start to close at the cervical/hindbrain boundary
    • at 26-28 cord closure at the upper sacral level is completed
      • average sibling risk for spina bifida is 2.8-4.6% compared to .1% in the regular population
      • operative technique includes a closure of the spinal contents and an overlying subcutaneous and skin closure; simultaneous placement of a shunt is an option
Spina Bifida Myelocele


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