How is head-shake nystagmus classified 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

Answer

Nystagmus produced after the head rotation is considered significant if at least 5 consecutive beats of at least 2 degrees per second are observed. Head-shake nystagmus is described by the following classifications:

  • Monophasic, in which the nystagmus produced does not change directions

  • Biphasic, in which the nystagmus produced initially beats in one direction and then fatigues and reverses directions

  • Paretic, in which the initial nystagmus observed beats away from the side of lesion

  • Reversed, in which the initial nystagmus observed beats toward the side of lesion

  • Cross-coupled, in which a strong vertical nystagmus is produced by head shaking on the horizontal axis


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