Nerve injuries: preganglionic brachial plexus lesion: practice question

A Orthopaedics 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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Orthopaedics · Nerve injuries: preganglionic brachial plexus lesion

Sample item

A motorcyclist has a flail, anaesthetic arm after a high-speed crash, with Horner syndrome and winging of the scapula. Sensory nerve action potentials in the anaesthetic hand are preserved. What does this combination indicate?

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

The answer and the reasoning

C. Preganglionic root avulsion proximal to the dorsal root ganglion

Preserved sensory nerve action potentials in an anaesthetic limb show that the sensory axons are still connected to their ganglion cells, so the lesion is proximal to the dorsal root ganglion. Horner syndrome, and winging from rhomboid and serratus paralysis, are further clues for root avulsion. Preganglionic injuries cannot be repaired, so nerve transfers are used.

Option by option

  • A. Neurapraxia that will recover spontaneously

    These features indicate a severe injury and not a recoverable neurapraxia.

  • B. Postganglionic rupture of the lower trunk

    A postganglionic lesion would abolish the sensory nerve action potentials distally.

  • C. Preganglionic root avulsion proximal to the dorsal root ganglion (correct)

    Correct. Preserved SNAP with Horner syndrome and winging suggests root avulsion.

  • D. Isolated axillary nerve palsy

    An axillary nerve palsy would not produce a flail arm with Horner syndrome.

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 Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is C, Preganglionic root avulsion proximal to the dorsal root ganglion. Preserved sensory nerve action potentials in an anaesthetic limb show that the sensory axons are still connected to their ganglion cells, so the lesion is proximal to the dorsal root ganglion.

Why is "Neurapraxia that will recover spontaneously" not the answer?

These features indicate a severe injury and not a recoverable neurapraxia.

Why is "Postganglionic rupture of the lower trunk" not the answer?

A postganglionic lesion would abolish the sensory nerve action potentials distally.

Why is "Isolated axillary nerve palsy" not the answer?

An axillary nerve palsy would not produce a flail arm with Horner syndrome.

What concept does this question test?

It tests Nerve injuries: preganglionic brachial plexus lesion in Orthopaedics. Horner syndrome, and winging from rhomboid and serratus paralysis, are further clues for root avulsion. Preganglionic injuries cannot be repaired, so nerve transfers are used.

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 Nerve injuries: preganglionic brachial plexus lesion?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics 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.