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How do audiologists use nystagmus to assess vestibular function?

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Audiologists assess vestibular system function by observing nystagmus, a characteristic slow-quick oscillatory eye movement. This involuntary movement often occurs spontaneously following a change in vestibular function or can be provoked by specific body movements.1

To evaluate the sensitivity of the vestibular organs, audiologists often use a caloric test. By irrigating the external ear canal with warm or cool water, they induce convection currents in the horizontal canal, which elicits nystagmus. The duration, rate, and amplitude of these eye movements are then measured or recorded—a process known as electronystagmography—to compare the function of the right and left ears. An abnormal vestibular apparatus typically produces a reduced response or no response at all.12

Additionally, rotation may be used to stimulate both ears simultaneously to elicit nystagmus and other vestibular ocular reflexes. These observations are critical for diagnosing balance disorders, as the vestibular system and eye movements are closely linked through the vestibular ocular reflex.21