Video Head Impulse Test (vHIT): Main Concepts

Abstract

Video Head Impulse Test (vHIT): Main ConceptsSubmit Manuscript | http://medcraveonline.com producing an eye movement in the opposite direction to head movement, thus preserving the image on the center of the visual field. It involves a 3-neuron arc that consists of the vestibular ganglion, vestibular nuclei, and oculomotor nuclei. With a latency period of only 8 to 12 milliseconds (ms), the VOR is considered the fastest reflex in humans.Supported on this mechanism the VOR can be evaluated using an equipment for recording the movement of the eyes and find quantitatively responses about this reflex, based on the gain between eye velocity/head velocity. The normal value is equal one for healthy subjects.

Comparison of two systems for the video head impulse test (vHIT) for the lateral semicircular canal: description of results from normal and pathological subjects

“…Several recommendations can be made in order to properly perform the vHIT: (1) The v-HIT goggles should be tightly fitted, preferably with controlled tension; (2) Hands should not directly touch the vHIT goggle or strap while manipulating the head; (3) In order to minimize the effect of the difference in rotation axis between the eyes and head, the minimum distance between the subject and the wall should be 1.5 meters; (4) The computer screen should be facing the observer, not the subject, in order to directly evaluate the VOR after the head impulse; (5) The subject must be given clear instructions to continuously focus on the object of fixation with the eyes wide open and relax the neck as much as possible when the head is returned to the neutral central position; and (6) VORs should be acquired at three ranges of head velocities: 100-150°/s, 150-200°/s and 200-250°/s 5,6,9,10,13,14 .…”

Balance Pediatric Evaluations and video Head Impulse Test (v-HIT): Use and Applications

“…While v-HIT is still considered very new to many clinicians, it is important to note that it relieves of use and its ability to asses VOR at a more real time frequency; furthermore, it is also able to asses all six semicircular canals Hülse [4], Felipe [2]. In the case of using it for testing children, it has been noted that this method is way more tolerable and easier to conduct when in comparison to what is considered the "gold-standard" for adults: the caloric test and rotary chair.…”

“…Video Head Impulse testing (v-HIT) is the first vestibular test that allows clinicians to evaluate the function of all six semicircular canals. It has been noted that this test has advantages in comparison to rotary chair and caloric testing when evaluating the vestibular function in children Hamilton [1], Felipe [2]. The v-HIT is the latest method that allow us to assess the vestibular ocular reflex (VOR), which is a key component when assessing vestibular function.…”

“…In a sense, v-HIT provides with the analysis of more "real life" scenario analysis of head movements which is vital especially when dealing with children. Another advantage to using v-HIT as a method of testing children is the ability for the testing to be quick and less intimidating an uncomfortable for a child which can provide comfort and establish trust with the patient and the family Felipe [2]. The purpose of this study is to highlight the clinical use of v-HIT when assessing vestibular and balance function in pediatric population and discussing its application and outcomes as known thus far.…”