Neuroimaging: Chiari malformation: practice question

A Radiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Radiology · Neuroimaging: Chiari malformation

Sample item

A neonate with a lumbar myelomeningocele has MRI showing a small posterior fossa with cerebellar tonsils and vermis displaced through the foramen magnum and a beaked tectum. What is the diagnosis?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Chiari II malformation

Chiari II is nearly always associated with myelomeningocele and shows a small posterior fossa, caudal displacement of the vermis and medulla, beaked tectum and hydrocephalus. Chiari I has isolated tonsillar descent of more than 5 mm and presents in adults. Folic acid prevents neural tube defects.

Option by option

  • A. Arachnoid cyst

    An arachnoid cyst is an extra-axial CSF collection.

  • B. Chiari II malformation (correct)

    Correct. Myelomeningocele with tonsillar and vermian descent is Chiari II.

  • C. Chiari I malformation

    Chiari I has only tonsillar descent without myelomeningocele.

  • D. Dandy-Walker malformation

    Dandy-Walker has an enlarged posterior fossa with a cystic fourth ventricle.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is B, Chiari II malformation. Chiari II is nearly always associated with myelomeningocele and shows a small posterior fossa, caudal displacement of the vermis and medulla, beaked tectum and hydrocephalus.

Why is "Arachnoid cyst" not the answer?

An arachnoid cyst is an extra-axial CSF collection.

Why is "Chiari I malformation" not the answer?

Chiari I has only tonsillar descent without myelomeningocele.

Why is "Dandy-Walker malformation" not the answer?

Dandy-Walker has an enlarged posterior fossa with a cystic fourth ventricle.

What concept does this question test?

It tests Neuroimaging: Chiari malformation in Radiology. Chiari I has isolated tonsillar descent of more than 5 mm and presents in adults. Folic acid prevents neural tube defects.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Neuroimaging: Chiari malformation?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.