Group 12 Docu


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Group 12 Docu

  1. 1. Group 12: Neural Tube Defect<br />Definition <br /><ul><li>Neural tube defects (NTDs) are a group of disorders that arise early in fetal development and can cause life-long complications of varying severity
  2. 2. During the first 3-4 weeks of development, specific cells in an embryo curl up and their edges fuse together to form a narrow tube that becomes the foundation of the spinal cord, brain, and the bone and tissues that surround it
  3. 3. This neural tube fusing process usually is complete by 28 days of gestation – before many women even know that they are pregnant
  4. 4. If the tube does not close properly along its entire length, then a NTD will form at the open location</li></ul>Incidence <br />The true incidence of Neural Tube Defects appears to be decreasing in most parts of the world.<br />Estimates of rate approximate 0.2-0.4 per 1000 live births <br />Low socio-economic background<br />Race/Geographical location<br />- eg: India, China, certain Hispanic subpopulation<br /><ul><li>Most common presentation of NTD:
  5. 5. Spina Bifida 55%
  6. 6. Anencephaly 45%
  7. 7. Encephalocele 5%</li></ul>Etiology of NTD<br />Anti-epilepsy medications<br />Folic acid deficiency<br />Folate antimetabolites (such as methotrexate) <br />Hyperthermia in early development<br />Insulin dependent diabetes melitus <br />Teratogens-arsenic, mycotoxins <br />Inherited with multifactorial pattern<br />Maternal weight and age<br />Risk assessment<br /><ul><li>Precise aetiology for the majority of these defects is unknown
  8. 8. Multifactorial causation (partgenetic)
  9. 9. Family history(2-5% risk if one affected child)
  10. 10. Folate deficiency
  11. 11. Anti-epileptic drugs : Valproic acid, Tegretal
  12. 12. IDDM</li></ul>Types <br /><ul><li>There are three types of NTDs :
  13. 13. Anencephaly
  14. 14. Spina bifida
  15. 15. Encephalocele
  16. 16. Anencephaly :
  17. 17. Characterized by absence of large part of the brain and the skull.
  18. 18. Causes: failure of closure of the cephalic end of the neural tube
  19. 19. Features:
  20. 20. infants are born without a forebrain
  21. 21. The remaining brain tissue is often exposed; it is not covered by bone or skin
  22. 22. Spina bifida :
  23. 23. (a congenital malformation) in which there is a bony defect in the vertebral column
  24. 24. so that part of the spinal cord, which is normally protected within the vertebral column, is exposed
  25. 25. caused by : the failure of the neural tube to close during embryonic development
  26. 26. Types of SB :
  27. 27. Spina bifida occulta (closed): 20%
  28. 28. Spina bifida manifesta (open): 80%
  29. 29. Meningocele: CSF only
  30. 30. Meningomyelocele( CSF+ Nerve fibers)
  31. 31. Encephalocele :
  32. 32. Is a severe birth defect
  33. 33. Caused by incomplete development of the skull that subsequently allows part of the brain to protrude through the hole in the skull
  34. 34. Babies with encephalocele ordinarily don't survive very long after birth, and if they do survive, they usually are severely mentally retarded </li></ul>Diagnosis <br />Can be done prenatal or after birth<br />Prenatal screening: <br />Measuring maternal serum alpha fetoprotein(AFP)<br />This is the first prenatal screening done at 15-20 weeks of gestation.<br />AFP is the major serum protein in early embryonic life. It is believed to be involved in preventing fetal immune rejection and is first made in the yolk sac and then later in the GI system and liver of the fetus.<br />AFP goes from the fetal blood stream to the fetal urinary tract, where it is excreted into the maternal amniotic fluid. It can also leak into the amniotic fluid from open neural tube defects in which the fetal blood stream is in direct contact with the amniotic fluid.<br />Concentration of more than 1000 ng/mL is indicative for NTD (normal:500 ng/mL)<br />More than 75% accurate.<br />Determining precise gestational age is essential because fetal AFP levels are age specific and can peak in a normal fetus at 12-15 weeks' gestation.<br />Measuring AFP in amniotic fluid (amniocentesis)<br />A diagnostic test.<br />More accurate especially at 15-20 weeks of gestation.<br />Detects approximately 98% of all neural tube defects.<br />Ultrasonography<br />A diagnostic test.<br />98% accurate.<br />After birth:<br />Physical exam<br />Spine X-ray<br />CT or MRI<br />Treatment<br />In utero: Surgery <br />Covering the neural placode with skin to decrease the damage inflicted to the exposed neural structures by amniotic fluid. <br />Closure of neural placode to decrease loss of CSF.<br />After birth:<br />Depends on the type of spina bifida.<br />Spina bifida occulta usually requires no treatment as it causes no symptoms<br />Spina bifida manifests require surgery often within the first 24 to 48 hours: <br />To protect the exposed spinal cord. <br />Help preserve whatever nerve function the baby has.<br />Help prevent infection of the exposed nerves and other tissues.<br />Prognosis<br />Depends on the nature of the defect and associated malformation<br />Infections<br />Associated motor and sensory problems, particularly lower limb<br />Associated learning disability, developmental delay and hearing impairment<br />Bladder and bowel dysfunction<br />Prevention<br />Periconceptional folic acid supplementation can prevent most neural tube defects if widely used. Supplementation must begin before conception for it to be effective. <br />To prevent first occurrence, women who are planning to become pregnant should take 400mcg folic acid daily before conception and during first 12 weeks of pregnancy. To prevent recurrence, 5mg/day folic acid should be taken.<br />Food fortification with the addition of folate to grain products is considered the most effective method of ensuring adequate intake of folic acid in pregnant women. <br />