What is alternating binaural bithermal caloric stimulation 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

Alternating binaural bithermal caloric stimulation, which is probably the most commonly used protocol for caloric stimulation, includes the following conditions:

  • Right ear cool (RC)

  • Left ear cool (LC)

  • Left ear warm (LW)

  • Right ear warm (RW)

This test order elicits nystagmus responses of opposing directions with each change in temperature or side (eg, left beating, then right beating). However, evidence shows that no physiological order effect is present after caloric irrigations. [17] Thus, for practical reasons, some practitioners recommend beginning with warm irrigation of the suspect ear, since that test result is the most useful for the assessment should the patient decline further testing at that point.

During each stimulation, the cool or warm stimulus is delivered for a preset time that is determined by the type of stimulus and normative data. The patient is instructed to engage in a mental task during delivery of the stimulus. After the stimulus is removed, recording continues while the patient is mentally tasked.

The patient is given a break of 3-5 minutes between the RC and LC calorics and between the LW and RW. A break of 8-10 minutes is given between the LC and LW conditions.

When adequate data have been recorded, fixation suppression testing is conducted.


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