How would you differentiate central from peripheral vestibular nystagmus on examination?

How would you differentiate central from peripheral vestibular nystagmus on examination?

• A. Peripheral nystagmus is unidirectional, fatigable, and reduced with fixation; central nystagmus may change direction and be nonfatigable, with other neurologic signs.
• B. Central nystagmus is unidirectional, fatigable, and reduced with fixation.
• C. Peripheral nystagmus direction changes with gaze; central remains unidirectional.
• D. Peripheral and central nystagmus cannot be distinguished clinically.

Answer: (C)

The key idea is that how nystagmus behaves during gaze testing helps distinguish peripheral from central causes. Peripheral vestibular nystagmus is typically unidirectional—its fast phase stays in the same direction no matter where you gaze—often horizontal or rotary, and it tends to fatigue with time and be reduced by visual fixation. Central vestibular nystagmus, on the other hand, can change direction with different gaze positions, may be vertical or torsional, is often nonfatigable, and is frequently accompanied by other neurological signs. So the option that describes peripheral nystagmus as unidirectional, fatigable, and reduced with fixation, while noting that central nystagmus may change direction with gaze and is nonfatigable (potentially with additional neurologic signs), best fits the real clinical differentiation. The other descriptions either misstate how direction behaves with gaze, attribute central features to peripheral nystagmus, or claim there’s no clinical distinction.

The key idea is that how nystagmus behaves during gaze testing helps distinguish peripheral from central causes. Peripheral vestibular nystagmus is typically unidirectional—its fast phase stays in the same direction no matter where you gaze—often horizontal or rotary, and it tends to fatigue with time and be reduced by visual fixation. Central vestibular nystagmus, on the other hand, can change direction with different gaze positions, may be vertical or torsional, is often nonfatigable, and is frequently accompanied by other neurological signs. So the option that describes peripheral nystagmus as unidirectional, fatigable, and reduced with fixation, while noting that central nystagmus may change direction with gaze and is nonfatigable (potentially with additional neurologic signs), best fits the real clinical differentiation. The other descriptions either misstate how direction behaves with gaze, attribute central features to peripheral nystagmus, or claim there’s no clinical distinction.