Special senses: vestibular function: practice question

A Physiology 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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Physiology · Special senses: vestibular function

Sample item

In a healthy person, cold water is irrigated into the right external ear canal during caloric testing. What nystagmus is expected?

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

The answer and the reasoning

D. Fast component to the left, with slow drift towards the right

Cold water lowers endolymph temperature in the right horizontal canal, reducing firing from that labyrinth. The brain interprets this as a turn towards the left, so slow eye drift goes towards the right (the cold ear) and a corrective fast phase beats to the left. The mnemonic COWS states that nystagmus is Cold Opposite, Warm Same.

Option by option

  • A. No nystagmus because the vestibulo-ocular reflex is suppressed

    The reflex is intact in healthy persons and the response is brisk.

  • B. Fast component to the right, with slow drift towards the left

    This would be the response to warm water in the right ear.

  • C. Vertical nystagmus with downward fast phase

    Horizontal canal stimulation produces horizontal nystagmus, not vertical.

  • D. Fast component to the left, with slow drift towards the right (correct)

    Correct. Cold water causes the fast phase to beat away from the irrigated ear.

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 Physiology question

What is the answer to this Physiology question?

The best answer is D, Fast component to the left, with slow drift towards the right. Cold water lowers endolymph temperature in the right horizontal canal, reducing firing from that labyrinth.

Why is "No nystagmus because the vestibulo-ocular reflex is suppressed" not the answer?

The reflex is intact in healthy persons and the response is brisk.

Why is "Fast component to the right, with slow drift towards the left" not the answer?

This would be the response to warm water in the right ear.

Why is "Vertical nystagmus with downward fast phase" not the answer?

Horizontal canal stimulation produces horizontal nystagmus, not vertical.

What concept does this question test?

It tests Special senses: vestibular function in Physiology. The brain interprets this as a turn towards the left, so slow eye drift goes towards the right (the cold ear) and a corrective fast phase beats to the left. The mnemonic COWS states that nystagmus is Cold Opposite, Warm Same.

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 Special senses: vestibular function?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.