Neurophysiology: syringomyelia: 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 · Neurophysiology: syringomyelia

Sample item

A 28-year-old has painless burns on both hands and bilateral loss of pain and temperature over the shoulders and arms, but retains light touch and vibration. What explains the pattern?

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

The answer and the reasoning

B. Interruption of crossing spinothalamic fibres in the anterior white commissure

A central cavity (syrinx) in the cervical cord interrupts fibres of the lateral spinothalamic tract as they cross in the anterior white commissure, giving a bilateral, cape-like dissociated sensory loss. Dorsal columns carrying touch and vibration remain intact. Painless injury to the hands is typical.

Option by option

  • A. Bilateral lesions of the corticospinal tracts

    Corticospinal damage causes weakness and spasticity, not sensory dissociation.

  • B. Interruption of crossing spinothalamic fibres in the anterior white commissure (correct)

    Correct. Crossing pain and temperature fibres are damaged while the dorsal columns are spared.

  • C. Compression of the cauda equina

    Cauda equina lesions affect the legs and sphincters, not the arms.

  • D. Damage to both dorsal columns

    Dorsal column loss would affect vibration and position, which are preserved here.

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 B, Interruption of crossing spinothalamic fibres in the anterior white commissure. A central cavity (syrinx) in the cervical cord interrupts fibres of the lateral spinothalamic tract as they cross in the anterior white commissure, giving a bilateral, cape-like dissociated sensory loss.

Why is "Bilateral lesions of the corticospinal tracts" not the answer?

Corticospinal damage causes weakness and spasticity, not sensory dissociation.

Why is "Compression of the cauda equina" not the answer?

Cauda equina lesions affect the legs and sphincters, not the arms.

Why is "Damage to both dorsal columns" not the answer?

Dorsal column loss would affect vibration and position, which are preserved here.

What concept does this question test?

It tests Neurophysiology: syringomyelia in Physiology. Dorsal columns carrying touch and vibration remain intact. Painless injury to the hands is typical.

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 Neurophysiology: syringomyelia?

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.