Prevention of neural tube defects

Question 1

Neural tube defects - types

Answer 1

1. Craniospinal defects occur early in development when the neural tube fails to close properly. Spina bifida and anencephaly make up over 95% of neural tube defects
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2. Anencephaly
   - Absence of skull vault and cerebvral cortex
   - Not compatible with life; babies rarely liver for more than a few hours if they are not stillborn

Spina bifida (incomplete fusion of vertebrae potentially allowing herniation of all or part of the spinal cord); malformation falls into three categories:

3. Spina bifida occulta (mildest) = split in vertebrae with no herniation of spinal cord, varies from asymptomatic to mild neurological symptoms
4. Meningocele (lest common) = split in vertebrae with herniation of meninges and cerebrospinal fluid (CSF), varies from normal neurological function to moderate symptoms
5. Myelomeningocele (most severe) = split in vertebrae which allows herniation of spinal cord and meninges; invariably have abnormal neurology at and below the lesion; usually have an abnormal cerebellum and hydrocephalus, which may result in mental impairment

Question 2

Prevention of NTDs

Answer 2

1. Dietary supplementation with folic acid decreases the incidence of NTDs. Recommended doses:
2. 500mcg daily for 3mo before conception, continued to 12 weeks
3. 5mg/d for women with previously affected child or those taking anticonvulsants