Definition
anencephalia; congenital defective development of the brain,
with absence of the bones of the cranial vault, the cerebral and
cerebellar hemispheres, a rudimentary brainstem, and traces of basal
ganglia. partial anencephaly
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Radiographic Appearance
Usually first identified on ultrasound as a failure to
visualise the cranial structures either completely or incompletely.
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Pathology
EPIDEMIOLOGY:
Incidence: 1/1000 live births
Age of onset: newborn
Risk factors: geographic variable with incidence increased in
Ireland and Wales and decreased in Asia, Africa, and South America
genetic; recurrence rate is 4% and increases to 10% if a
couple has had 2 previous anencephalic infants whites > blacks (6:1)
F > M
PATHOGENESIS:
1. Background
anencephaly arises from an embryonic defect occurring prior to day
26 which prevents the closure of the anterior neuropore - the
frequency of anencephaly has decreased during past 2 decades - CNS
findings:
both cerebral hemispheres and thus the spinal cord pyramidal tracts
are absent
absence of the cerebellum
residue of the brainstem usually present
hypoplastic pituitary gland
the rudimentary brain remaining consists of portions of con-nective
tissue, vessels, and neuroglia
CLINICAL FEATURES:
1. Anencephaly
distinctive appearance: a large defect in the vault of the skull (calvarium),
meninges, and scalp exposes a soft angiomatous mass of neural tissue
covered with a thin membrane continuous with the skin
the cranial defect may extend inferiorly to the cervical region
exposing a thin and flattened spinal cord (craniorachischisis)
the optic globes may protrude due to inadequately-formed bony orbits
MANAGEMENT:
No Treatment
Most infants are stillborn or die within several days of birth
Organ donation is controversial
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Treatment
Non
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Image 1
Anencaphilic foetus
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2 Ultrasound of an Anencaphilic foetus
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