Peripheral nerve injuries: nerve conduction in carpal tunnel: 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.

Try it

Orthopaedics · Peripheral nerve injuries: nerve conduction in carpal tunnel

Sample item

Which finding on nerve conduction studies supports the diagnosis of carpal tunnel syndrome?

APreserved sensory potentials in a numb, paralysed handBProlonged distal motor and sensory latency of the median nerveCSlowed conduction of the ulnar nerve at the elbowDNormal median conduction with fibrillation in the biceps

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

The answer and the reasoning

B. Prolonged distal motor and sensory latency of the median nerve

Compression at the wrist demyelinates the median nerve locally, so impulses are delayed across the carpal tunnel. Distal motor latency to abductor pollicis brevis and sensory latency to the fingers are prolonged, and in severe cases amplitudes fall.

Option by option

A. Preserved sensory potentials in a numb, paralysed hand
Preserved sensory potentials with an anaesthetic hand indicate a root avulsion proximal to the ganglion, not a wrist lesion.
B. Prolonged distal motor and sensory latency of the median nerve (correct)
Correct. Focal slowing across the wrist delays median nerve conduction.
C. Slowed conduction of the ulnar nerve at the elbow
Slowing of ulnar nerve conduction across the elbow suggests cubital tunnel syndrome.
D. Normal median conduction with fibrillation in the biceps
Biceps fibrillation points toward a C5-6 or musculocutaneous problem and not the wrist.

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.

Questions about this Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is B, Prolonged distal motor and sensory latency of the median nerve. Compression at the wrist demyelinates the median nerve locally, so impulses are delayed across the carpal tunnel.

Why is "Preserved sensory potentials in a numb, paralysed hand" not the answer?

Preserved sensory potentials with an anaesthetic hand indicate a root avulsion proximal to the ganglion, not a wrist lesion.

Why is "Slowed conduction of the ulnar nerve at the elbow" not the answer?

Slowing of ulnar nerve conduction across the elbow suggests cubital tunnel syndrome.

Why is "Normal median conduction with fibrillation in the biceps" not the answer?

Biceps fibrillation points toward a C5-6 or musculocutaneous problem and not the wrist.

What concept does this question test?

It tests Peripheral nerve injuries: nerve conduction in carpal tunnel in Orthopaedics. Distal motor latency to abductor pollicis brevis and sensory latency to the fingers are prolonged, and in severe cases amplitudes fall.

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 Peripheral nerve injuries: nerve conduction in carpal tunnel?

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.