What is a vibration-induced nystagmus test in electronystagmography (ENG)?

Updated: Aug 06, 2019
  • Author: Angela G Shoup, PhD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Nystagmus may be induced in patients by stimulating the head and/or neck with vibrations. Vibration-induced nystagmus may be useful in the diagnostic confirmation of unilateral lesions.

For vibration-induced nystagmus, the patient is placed in an upright sitting position and a vibrator is applied to the mastoid. Eye movements are recorded in the dark while a vibratory stimulus of 100 Hz is presented to the mastoid. Recordings should be obtained separately for the right and left mastoid. Vibratory stimulation may likewise be presented to the sternocleidomastoid muscles to induce vibration-induced nystagmus. The vibration-induced nystagmus test should be considered with caution if the patient has any history of a detached retina.

A positive finding of vibration-induced nystagmus occurs when nystagmus appears during vibratory stimulation and disappears when the stimulation terminates. The nystagmus may have several components but is predominantly horizontal. Healthy subjects have reportedly displayed up to 1.5 degrees per second of vibration-induced nystagmus with mastoid stimulation. [24]

In patients with a unilateral lesion, the vibration-induced nystagmus most often beats in the direction of the nonaffected side. The exception to this is Meniere disease, in which the vibration-induced nystagmus may beat in either direction. [25]


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