Timothy C. Hain, MD Page last modified: December 1, 2016
|Covert saccades in patient with complete vestibular loss on R. Now most of the saccades occur within the head thrust.||Same patient, 1 year earlier. More "overt" saccades -- defined as those around 200 ms and later.|
The illustration above shows how the VHIT test can change as patients get better at compensation.
The ability to detect "covert" saccades, as illustrated above, is what makes the VHIT device better than just doing the HIT test by hand. We have observed patients with "covert" saccades as early as 1 week post vestibular neuritis, while on large amounts of meclizine. We have also observed "overt" saccades in patients more than 1 year "out" from unilateral loss. Thus, it would seem that there is a lot to learn about the supposed ability of covert/overt saccades to detect compensation.