What is the role of the head-shake nystagmus test in the diagnosis of dizziness, vertigo, and imbalance?

Updated: Mar 13, 2017
  • Author: Hesham M Samy, MD, PhD; Chief Editor: Robert A Egan, MD  more...
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Answer

Head movements produce vestibular responses with an extremely short latency (< 15 msec). Oculomotor responses are slower than this, with latencies approaching 100-200 msec. The compensation for this temporal discrepancy is the ability of the central vestibular system to maintain a memory of head motion, so that eye movements can be accurately matched to head movement.

This capability, referred to as velocity storage, is usually impaired with unilateral vestibular deficit and is tested by the head-shake test. In this test, 20 cycles of low-amplitude, high-velocity active or passive head movements are performed, followed by observation for nystagmus. This is done in both horizontal and vertical directions. Observation must be done with suppression of visual fixation by means of Frenzel goggles or an infrared video system. Head-shake nystagmus is seen with uncompensated, unilateral vestibular hypofunction.


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