Neuroanatomy: syringomyelia: practice question

A Anatomy 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

Anatomy · Neuroanatomy: syringomyelia

Sample item

A 30-year-old man has painless burns on his hands. He has loss of pain and temperature in a cape-like distribution over both shoulders and arms, with preserved touch and vibration. Which structure is damaged first?

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

The answer and the reasoning

B. Crossing spinothalamic fibres in the anterior white commissure

A cavity (syrinx) expanding in the central canal region of the cervical cord interrupts pain and temperature fibres as they cross in the anterior white commissure, giving a suspended, cape-like sensory loss. Touch and vibration are carried in the posterior columns and are spared (dissociated sensory loss). Painless burns result from the analgesia.

Option by option

  • A. Lateral corticospinal tract

    The corticospinal tract damage causes spastic weakness, which comes later with enlargement of the syrinx.

  • B. Crossing spinothalamic fibres in the anterior white commissure (correct)

    Fibres crossing in the anterior white commissure carry pain and temperature at the segment of the syrinx.

  • C. Dorsal root ganglia

    Damage to dorsal root ganglia would produce segmental loss of all modalities.

  • D. Posterior columns

    Posterior column damage would reduce vibration and joint position sense, 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.

More Anatomy questions

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is B, Crossing spinothalamic fibres in the anterior white commissure. A cavity (syrinx) expanding in the central canal region of the cervical cord interrupts pain and temperature fibres as they cross in the anterior white commissure, giving a suspended, cape-like sensory loss.

Why is "Lateral corticospinal tract" not the answer?

The corticospinal tract damage causes spastic weakness, which comes later with enlargement of the syrinx.

Why is "Dorsal root ganglia" not the answer?

Damage to dorsal root ganglia would produce segmental loss of all modalities.

Why is "Posterior columns" not the answer?

Posterior column damage would reduce vibration and joint position sense, which are preserved here.

What concept does this question test?

It tests Neuroanatomy: syringomyelia in Anatomy. Touch and vibration are carried in the posterior columns and are spared (dissociated sensory loss). Painless burns result from the analgesia.

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 Neuroanatomy: syringomyelia?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy 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.