Neurophysiology: dorsal column loss: 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: dorsal column loss

Sample item

A 55-year-old man with tabes dorsalis stands steadily with eyes open but sways and falls when he closes them. Which mechanism explains this Romberg sign?

ALoss of motor strength from corticospinal damageBLoss of spinothalamic pain pathwaysCLoss of cerebellar vermis functionDLoss of dorsal column proprioception, leaving balance dependent on vision

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

The answer and the reasoning

D. Loss of dorsal column proprioception, leaving balance dependent on vision

Balance uses proprioceptive, vestibular and visual inputs. In tabes dorsalis, degeneration of the dorsal columns and roots abolishes proprioceptive input, and the patient compensates with vision, so closing the eyes unmasks instability (sensory ataxia). Cerebellar ataxia is unsteady with eyes open as well.

Option by option

A. Loss of motor strength from corticospinal damage
Weakness does not produce a selective eyes-closed instability.
B. Loss of spinothalamic pain pathways
Pain pathways do not contribute to postural balance.
C. Loss of cerebellar vermis function
Cerebellar lesions cause unsteadiness regardless of whether the eyes are open.
D. Loss of dorsal column proprioception, leaving balance dependent on vision (correct)
Correct. Without joint position sense, vision becomes the main stabiliser.

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 Physiology question

What is the answer to this Physiology question?

The best answer is D, Loss of dorsal column proprioception, leaving balance dependent on vision. Balance uses proprioceptive, vestibular and visual inputs.

Why is "Loss of motor strength from corticospinal damage" not the answer?

Weakness does not produce a selective eyes-closed instability.

Why is "Loss of spinothalamic pain pathways" not the answer?

Pain pathways do not contribute to postural balance.

Why is "Loss of cerebellar vermis function" not the answer?

Cerebellar lesions cause unsteadiness regardless of whether the eyes are open.

What concept does this question test?

It tests Neurophysiology: dorsal column loss in Physiology. In tabes dorsalis, degeneration of the dorsal columns and roots abolishes proprioceptive input, and the patient compensates with vision, so closing the eyes unmasks instability (sensory ataxia). Cerebellar ataxia is unsteady with eyes open as well.

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: dorsal column loss?

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.