Neuroimaging: CT before lumbar puncture: 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: CT before lumbar puncture

Sample item

A patient with fever and neck stiffness has a Glasgow Coma Scale of 11 and papilloedema. Before lumbar puncture, which step is needed?

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

The answer and the reasoning

B. Non-contrast CT of the head

Altered consciousness and papilloedema suggest raised intracranial pressure, so CT head is done first to exclude a mass lesion or shift that could cause herniation after lumbar puncture. Skull films do not show brain pathology. An electroencephalogram or Doppler will not exclude a mass.

Option by option

  • A. Carotid Doppler

    A carotid Doppler examines neck vessels and not intracranial pressure.

  • B. Non-contrast CT of the head (correct)

    Correct. CT excludes a mass or shift that would make lumbar puncture dangerous.

  • C. Plain skull radiograph

    A skull radiograph shows bone only and cannot exclude brain shift.

  • D. Electroencephalogram

    An EEG shows electrical activity and not structural lesions.

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, Non-contrast CT of the head. Altered consciousness and papilloedema suggest raised intracranial pressure, so CT head is done first to exclude a mass lesion or shift that could cause herniation after lumbar puncture.

Why is "Carotid Doppler" not the answer?

A carotid Doppler examines neck vessels and not intracranial pressure.

Why is "Plain skull radiograph" not the answer?

A skull radiograph shows bone only and cannot exclude brain shift.

Why is "Electroencephalogram" not the answer?

An EEG shows electrical activity and not structural lesions.

What concept does this question test?

It tests Neuroimaging: CT before lumbar puncture in Radiology. Skull films do not show brain pathology. An electroencephalogram or Doppler will not exclude a mass.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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: CT before lumbar puncture?

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.