Korean J Otorhinolaryngol-Head Neck Surg.  2015 Aug;58(8):547-551. 10.3342/kjorl-hns.2015.58.8.547.

Changes of the Video Head Impulse Test Gains by the Directions of Head Rotation at Different Target Distances and Rotation Speeds

Affiliations
  • 1Department of Otolaryngology-Head and Neck Surgery, Jeju National University School of Medicine, Jeju, Korea.
  • 2Department of Otolaryngology-Head and Neck Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. dzness@amc.seoul.kr
  • 3Department of Otolaryngology-Head and Neck Surgery, Korea University Ansan Hospital, Ansan, Korea.

Abstract

BACKGROUND AND OBJECTIVES
The conventional instrument for video head impulse test (vHIT) records the movement of the right eye only. The aim of this study was to evaluate the changes in the gain of vHIT results qdue to different directions of head rotation directons at different target distances and rotation speeds.
SUBJECTS AND METHOD
Horizontal head impulse was recorded by vHIT in 20 normal subjects. vestibulo-ocular reflex (VOR) gains to the right and left directions were compared at different test conditions. Two different impulses with low (50-150 deg/sec) and high (200-300 deg/sec) peak-head-velocities were tested and the subjects were also instructed to fixate a laser dot on a screen at different distances of 60, 100, and 200 cm. Eye movements were recorded on the right eye.
RESULTS
Regardless of the target distances and peak-head-velocities, the VOR gains to the rightward head rotation were significantly greater than those to the leftward head rotation. In more than 85% of normal subjects, vHIT gain to the rightward head rotation was greater than that to the leftward head rotation. Mean gain asymmetries were 2.16-3.33% and the mean interaural vHIT gain differences were 0.04-0.07.
CONCLUSION
Regardless of the target distances and peak-head-velocities, the VOR gains to the rightward head rotation were significantly greater than those to the leftward head rotation. Directional asymmetry of VOR gain should be considered when interpreting vHIT results in patients with vestibular disorders.

Keyword

Interaural difference; Vestibule-ocular reflex; Video head impulse test

MeSH Terms

Eye Movements
Head Impulse Test*
Head*
Humans
Reflex, Vestibulo-Ocular
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