Neuroanatomy: posterior column disease: 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.

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Anatomy · Neuroanatomy: posterior column disease

Sample item

A 55-year-old man has lightning-like leg pains and an unsteady gait that is worse in the dark. Romberg sign is positive, ankle jerks are absent, and the pupils are small and irregular, accommodating but not reacting to light. Which tract is mainly degenerated?

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

The answer and the reasoning

A. Posterior column (fasciculus gracilis) and dorsal roots

Tabes dorsalis of tertiary syphilis damages the dorsal roots and posterior columns, particularly the fasciculus gracilis carrying position and vibration sense from the lower limb. Loss of proprioception causes sensory ataxia, which is worse in the dark and shown by the Romberg sign, and loss of the afferent limb of reflexes abolishes ankle jerks. Argyll Robertson pupils are also typical.

Option by option

  • A. Posterior column (fasciculus gracilis) and dorsal roots (correct)

    The posterior column and dorsal roots carry proprioception, and their loss produces sensory ataxia and areflexia.

  • B. Lateral corticospinal tract

    Corticospinal tract damage causes spasticity and brisk reflexes.

  • C. Lateral spinothalamic tract

    Spinothalamic damage causes loss of pain and temperature, while the gait ataxia here points to proprioceptive loss.

  • D. Ventral spinocerebellar tract

    The ventral spinocerebellar tract has a minor role and its damage does not give Romberg sign and areflexia.

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 A, Posterior column (fasciculus gracilis) and dorsal roots. Tabes dorsalis of tertiary syphilis damages the dorsal roots and posterior columns, particularly the fasciculus gracilis carrying position and vibration sense from the lower limb.

Why is "Lateral corticospinal tract" not the answer?

Corticospinal tract damage causes spasticity and brisk reflexes.

Why is "Lateral spinothalamic tract" not the answer?

Spinothalamic damage causes loss of pain and temperature, while the gait ataxia here points to proprioceptive loss.

Why is "Ventral spinocerebellar tract" not the answer?

The ventral spinocerebellar tract has a minor role and its damage does not give Romberg sign and areflexia.

What concept does this question test?

It tests Neuroanatomy: posterior column disease in Anatomy. Loss of proprioception causes sensory ataxia, which is worse in the dark and shown by the Romberg sign, and loss of the afferent limb of reflexes abolishes ankle jerks. Argyll Robertson pupils are also 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 Neuroanatomy: posterior column disease?

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.