Anencephaly : A severe Birth defect

Anencephaly- Clinical features, pregnancy diagnosis, prevention and treatment.

Spina Bifida and anencephaly are most common Neural Tube Defect ( NTD) followed by encephalocele.  Anencephaly is a severe form of NTD, with 100% mortality. The baby is either born dead or is unfit for survival.
Anencephaly is a congenital birth defect (from the Latin congenitus, “born with”)

Incidence Of Anencephaly: 1 in 1000 children ( world statistics, exact for Nepal is not available). In USA data is 1 in 150,000 to 200,000 babies born each year are anancephalic .

Cause Of Anencephaly:

• The anomaly results from deficient development development of the vault of skull and brain tissue due to incomplete closure of the Rostral Neuropores.

Clinical Features

• The facial portion is present. Infants with this disorder are born without a scalp or cerebellum. Their meninges, both hemispheres of the brain and the vault of the cranium/skull are also missing, though they usually do have part of the brain stem. The remaining brain tissue is protected only by a thin membrane.
• About ¼ of anencephalic babies die at birth; those who survive have a life expectancy of a few hours or days
• A baby born with anencephaly is usually blind, deaf, unconscious, and unable to feel pain. Although some  may be born with a main brain stem, the lack of a functioning cerebrum permanently rules out the possibility gaining consciousness.
• Reflex actions such as breathing and responses to sound or touch occur.
• The pituitary gland is often absent or if present is hypoplastic. Secondary to absence of stimulation in absence of ACTH , pituitary glands are also atrophied.

Risk Factors:

• Previous history of birth of infant with NTD
• 70 % of the cases are female .
• It is most common in first birth and among young and elderly mothers.
• Genetic and environmental factors are suspected to be involved.

Diagnosis Of Anencephaly:

1. In the first half of pregnancy, the diagnosis is made by elevated Alpha-fetoprotein in Amniotic fluid and confirmed by sonography. The findings around 13 weeks gestation are:- Absence of Cranial vault, Angiomatous brain tissue.
2. In later half of pregnancy, the diagnosis may be a problem.  Hydraminous and inability to palpate fetal head can arouse suspicion.
3. Face presentation is revealed by internal examination ( per vaginum).
4. Confirmation  is done by USG or X ray.

Complications:

1. Hydramnios
2. Malpresentation – face or breech
3. Premature labour
4. Tendency to post-maturity
5. Shoulder dystocia
6. Obstructed labour – if head and shoulder present (compound) due to short neck

Management:

• If diagnosed before 20 weeks of pregnancy: Termination of Pregnancy is done
• If Diagnosed Late:  PGE2 (Cerviprim gel can be used to to terminated the pregnancy as Uterus is usually resistant to Oxytocin.
• If Diagnosed During labor- The labor is likely to be prolonged. For Shoulder dystocia- Cleidotomy should be done. ( Cutting the clavicle bones)

Prevention Of Anencephaly:

1. Pre-pregnancy Counselling is important.
2. Folic Acid supplementation 4 weeks before the conception to 12 of pregnancy  has reduced the incidence of NTD significantly.    A dose of 4 mg daily is recommended.
3. Regular follow up visits Antenatal.
4. Mothers on drug ( Antiepileptics) should consult the doctor.

Gallery:

Source : DC Dutta Obstetrics book, Wikipedia, www.anencephalie-info.org .