Anencephaly

Anencephaly is a neural tube defect (NTD) that happens during embryonic fetal development. The neural tube is a narrow channel in the head and spinal cord. It normally folds and closes between the third and fourth weeks of pregnancy. Anencephaly occurs when the head end of the neural tube (cephalic end) fails to close. This causes a major portion of the brain, skull and scalp not to develop. Infants with this disorder are born without the front part of the brain (forebrain) and the thinking and coordinating part of the brain (cerebrum). The remaining brain tissue is often not covered by bone or skin (exposed).

CAUSES

The cause is unknown. The mother's diet and vitamin intake may play a role. Other factors could include:

  • Genetics (heredity).

  • Environment (toxic chemicals like lead or mercury).

  • Medications for epilepsy and diabetes.

  • Living in certain areas of the world.

  • Certain ethnic backgrounds.

Recent studies have shown that adding folic acid (vitamin B9) to the diet of women in their childbearing years may greatly reduce the incidence of neural tube defects because of the abnormal metabolism of folate. It is recommended that all women of childbearing age take folic acid daily. The usual dosage is 400 micrograms (0.4 mg) daily taken before getting pregnant and 4 mgs a day before getting pregnant if you had a child with a NTD.

SYMPTOMS

A baby born with this disorder is usually:

  • Blind.

  • Deaf.

  • Unconscious.

  • Unable to feel pain.

Some children with anencephaly may be born with a rudimentary brainstem. But the lack of a functioning cerebrum permanently rules out the possibility of ever gaining consciousness. Reflex actions such as breathing and responses to sound or touch may occur.

DIAGNOSIS

Diagnosis is suspected when the prenatal screening test for alpha-fetoprotein is abnormal. Then, fluid is removed from the amniotic sac (amniocentesis) and an ultrasound is performed. All pregnant women should have prenatal testing for possible abnormalities.

TREATMENT

There is no cure or treatment for this disorder. Any kind of treatment, nutrition, hydration with fluids and oxygen do not help. Treatment is supportive. The likely outcome for babies born with anencephaly is extremely poor.

PREVENTION

Taking folic acid (400 micrograms [0.4 mg]) daily, prior to getting pregnant, usually prevents NTDs. This is not 100% effective. Women with a high risk for NTDs should take 4 mg a day of folic acid before getting pregnant.