Which neural tube defect results from failure of the cranial end to close and may present with a froglike facial appearance?

Which neural tube defect results from failure of the cranial end to close and may present with a froglike facial appearance?

• A. Anencephaly
• B. Encephalocele
• C. Spina Bifida Occulta
• D. Caudal Regression

Answer: (A)

Failure of the cranial end to close during early neurulation produces anencephaly. When the cranial neural tube doesn’t seal, the forebrain and most of the skull fail to form, leaving only a rudimentary brainstem and no calvarium. This results in a markedly underdeveloped head and a characteristic froglike facial appearance, which comes from the absence of the skull bones overlaying the face and the exposed facial features. Clinically, this condition is often accompanied by polyhydramnios, since the fetus cannot swallow amniotic fluid normally. On ultrasound you would expect to see an absent or severely underdeveloped cranial vault with exposed neural tissue, and the face may have a distinctive frog-like appearance due to the lack of an intact skullcap. The other neural tube defects listed have different patterns: an encephalocele involves herniation of brain and meninges through a skull defect; spina bifida occulta is a subtle tuft of hair or vertebral defect at the spine without cranial involvement; and caudal regression affects the lower spine, not the cranial end.

Failure of the cranial end to close during early neurulation produces anencephaly. When the cranial neural tube doesn’t seal, the forebrain and most of the skull fail to form, leaving only a rudimentary brainstem and no calvarium. This results in a markedly underdeveloped head and a characteristic froglike facial appearance, which comes from the absence of the skull bones overlaying the face and the exposed facial features. Clinically, this condition is often accompanied by polyhydramnios, since the fetus cannot swallow amniotic fluid normally.

On ultrasound you would expect to see an absent or severely underdeveloped cranial vault with exposed neural tissue, and the face may have a distinctive frog-like appearance due to the lack of an intact skullcap. The other neural tube defects listed have different patterns: an encephalocele involves herniation of brain and meninges through a skull defect; spina bifida occulta is a subtle tuft of hair or vertebral defect at the spine without cranial involvement; and caudal regression affects the lower spine, not the cranial end.