Anencephaly is the absence of a major portion of the brain, skull, and scalp that occurs during embryonic development.[1] It is a cephalic disorder that results from aneural tube defect that occurs when the rostral (head) end of the neural tube fails to close, usually between the 23rd and 26th day following conception. it is accepted that children born with this disorder usually only lack a telencephalon,[3]the largest part of the brain consisting mainly of the cerebral hemispheres, including the neocortex, which is responsible for cognition. "A baby born with anencephaly is usually blind, deaf, unaware of its surroundings and unable to feel pain. Although some individuals with anencephaly may be born with a main brain stem, the lack of a functioning cerebrum permanently rules out the possibility of ever gaining awareness of their surroundings. Reflex actions such as breathing and responses to sound or touch may occur." The cause of anencephaly is disputed by medical professionals and researchers. Folic acid has been shown to be important in neural tube formation since at least 1995, and as a subtype of neural tube defect, folic acid may play a role in anencephaly. Studies have shown that the addition of folic acid to the diet of women of child-bearing age may significantly reduce, although not eliminate, the incidence of neural tube defects.
After birth to few hours to day. But in usa cases found who survive for about 2-3 year life then die.
