Functional Testing of all Six Semicircular Canals with Video Head Impulse Test Systems

Throughout the last decade, there has been a rapid development of existing test procedures and methods evaluating the human vestibular system. In 2009 and 2013, commercially available video Head Impulse Testing (vHIT) has enabled clinicians to examine the function of all three paired semicircular canals within the vestibular system. The vHIT test has revolutionized vestibular testing and, at many clinics and hospitals around the world, this test is now considered the most important initial test of vertiginous patients. There are several manufacturers of vHIT systems around the world. A test protocol for two of the most widespread vHIT systems, EyeSeeCam and ICS Impulse, will be presented. Included in this protocol is a description of the two different test methods termed 2D vHIT testing and 3D vHIT testing. The vHIT system includes a lightweight goggle with accompanying software. The test is fast (5-10 min) and can be done with minimal discomfort to the person being examined. However, there are many steps of the test, and each of these steps may alter the final test results, if the individual steps of the test are not performed correctly. It is therefore of paramount importance that the examiner is familiar with the potential noise and/or artifact triggers. Systematic training of future examiners before performing vHIT in a clinical setting and compliance with this protocol may minimize these challenges of the test. The vHIT test is not just a "plug and play" test. However, if carried out correctly, this test offers excellent objective assessment of the function of the high frequency domain of the vestibular system. It has a very high positive predictive value and offers a specificity very close to one hundred percent.