Vestibular tests Flashcards
what is the vestibular head impulse test
head is rapidly moved while the patient is asked to keep their eyes on a certain target
what do catch up saccades mean in vestibular head impulse test
VOR abnormailty
- occurs on the left = left side VOR problem
what is nystagmus
eye mvmts that occur under continuous vestibular stimulation
what is caloric vestibular testing
looking at SC canals while patient is laying down
- done by heating and cooling endolymph fluid
what occurs when endolymph fluid is heated
heated fluid rises, cools down, and then falls
- creates convection circle
= increased firing rate
what occurs when endolymph fluid is cooled
cooled fluid fall down, warmed by body heat, and rises
- creates convection circle
= decreased firing rate
what happens when the endolymph fluid is heated on one side and cooled on the other
vestibular input tells us our head is moving
- causes catch up saccades in the eyes to “stay focussed on the target”
what is rotational / translational vestibular testing
robotic chair that rotates and moves in different ways
- used to have the patient determine which way they are moved without any external info (VS input only)
what is electrical vestibular stimulation
low intensity current (<10mA) delieved through the mastoid process to stimulate all the vestibular afferents
- gives an artifical / virtual vestibular sensation of mvmt
what is the relationship between the + and - ends of the EVS and the firing rate of afferents
- side = increased firing rate
+ side = decreased firing rate
what occurs during balance response training with EVS
subjects will sway towards the positive electrode
(think they’re leaning to the side and try to correct)
what does the direction of EVD evoked balance response depend on
head position
(crainiocentric)
- can get different reflexes with different head positions
