Which statement about fixation suppression of nystagmus is true?

• A. Nystagmus in peripheral vertigo is typically suppressed by fixation; central vertigo is not consistently suppressed.
• B. Nystagmus in peripheral vertigo is never suppressed by fixation; central vertigo is sometimes suppressed.
• C. Nystagmus in peripheral vertigo is suppressed by fixation; central vertigo is less likely to be suppressed by fixation.
• D. Fixation suppression affects central vertigo only.

Answer: (C)

Fixation suppression tests how well a patient’s visual focus can dampen abnormal eye movements, and the pattern helps distinguish where the problem lies. When the vestibular system on one side is impaired (peripheral vertigo), the nystagmus is largely driven by an imbalance that the brain can dampen when the eyes fixate on a target. The intact central pathways can use fixation to reduce the reflex, so the nystagmus tends to diminish or disappear with fixation.

If the issue is central (involving brainstem or cerebellar circuits), the nystagmus arises from more complex, centrally generated signals that are not as easily suppressed by fixation, so it often persists or is only partially reduced despite steady gaze.

So the true statement reflects that peripheral nystagmus is typically suppressed by fixation, whereas central nystagmus is less likely to be suppressed. The other options either claim suppression never occurs, is exclusive to central vertigo, or that fixation only affects central vertigo, which doesn’t fit the usual pattern.