Exencephaly is a lethal congenital fetal brain developmental anomaly (neural tube defect) considered to be a precursor to anencephaly in the acrania-exencephaly-anencephaly sequence.

It is characterized by calvarial absence and loss of fetal brain tissue to variable degrees and is considered a precursor to anencephaly 3 in the acrania-exencephaly-anencephaly sequence.

  • maternal serum alpha fetoprotein (MSAFP) levels are highly elevated (x 2.5 MoM)

Imaging features have some overlap with that of anencephaly except that there is some brain tissue presence:

  • cranial vault is absent or poorly formed, cephalad to orbits
  • the nasal bone may be absent in most cases
  • brain tissue is herniating or dangling in amniotic fluid
  • brain tissue may be attached to the amniotic membrane

Exencephaly is a precursor to anencephaly, and essentially a fatal condition. Depending on local laws, advise and counseling for abortion are to be given to the parents.

  • acrania: calvarial absence but almost all brain tissue present
  • anencephaly: absence of calvarium as well as brain tissue

Article information

rID: 13935
Tag: cases, cases
Synonyms or Alternate Spellings:

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Cases and figures

  •  Case 1
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  • Case 2
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