Regional anaesthesia: nerve stimulator threshold: practice question

A Anaesthesia 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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Anaesthesia · Regional anaesthesia: nerve stimulator threshold

Sample item

During a nerve-stimulator-guided block, a motor response persists at a current of 0.15 mA. What is the best action?

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

The answer and the reasoning

C. Withdraw the needle slightly before injecting

An adequate response is expected between about 0.2 and 0.5 mA. A response at below 0.2 mA suggests that the needle tip may be in or against the nerve, and injection risks intraneural placement and nerve injury. The needle is withdrawn slightly until the response requires a higher current.

Option by option

  • A. Increase the current to 2 mA and inject

    Raising the current does not address the needle position.

  • B. Advance the needle further

    Advancing the needle risks nerve puncture.

  • C. Withdraw the needle slightly before injecting (correct)

    Correct. A very low threshold suggests intraneural placement, so the needle is repositioned.

  • D. Inject the full dose immediately

    Injecting at this threshold risks intraneural injection.

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 Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is C, Withdraw the needle slightly before injecting. An adequate response is expected between about 0.

Why is "Increase the current to 2 mA and inject" not the answer?

Raising the current does not address the needle position.

Why is "Advance the needle further" not the answer?

Advancing the needle risks nerve puncture.

Why is "Inject the full dose immediately" not the answer?

Injecting at this threshold risks intraneural injection.

What concept does this question test?

It tests Regional anaesthesia: nerve stimulator threshold in Anaesthesia. 2 and 0.5 mA. A response at below 0.2 mA suggests that the needle tip may be in or against the nerve, and injection risks intraneural placement and nerve injury. The needle is withdrawn slightly until the response requires a higher current.

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 Regional anaesthesia: nerve stimulator threshold?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.