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Neuropores fail to fuse by the 4th week of development Ž persistent connection between amniotic cavity and spinal canal. Associated with diabetes and folate deficiency during pregnancy. Increased α-fetoprotein (AFP) in amniotic fluid and serum (except spina bifida occulta = normal AFP).  Increased acetylcholinesterase (AChE) in amniotic fluid is a helpful confirmatory test.

The Nervous System

Spina bifida occulta

• Failure of caudal neuropore to close, but no herniation. Usually seen at lower vertebral levels. Dura is intact. Associated with tuft of hair or skin dimple at level of bony defect.