vestib - objective exam

Question 1

what are the 5 main components of the vestib objective exam

Answer 1

1. oculomotor exam
2. head thrust / head impulse test
3. head shaking induced nystagmus test
4. dynamic visual acuity test (DVA)
5. positional testing of SCC

Question 2

what are 8 things to look at in the oculomotor exam

Answer 2

ocular alignment
EOM
smooth pursuits
saccades
vergence
GEN
spontaneous nystagmus
VORc

Question 3

what are 4 types of misalignments seen in resting eye position

Answer 3

esotropia
exotropia
hypotropia
hypertropia

Question 4

ocular alignment: normal vs abnormal (and likely cause)

Answer 4

normal: position symmetrical
abnormal: misalignment
- spontaneous nystagmus (peripheral or central lesion)

Question 5

what is the function of normal EOM

Answer 5

eyes move in concert
-> brain takes input from each and puts it together to form a single image

Question 6

what is the test to screen EOM

Answer 6

test 6 cardinal positions in H pattern holding tip of finger 18-24in from eyes

Question 7

EOM: normal vs abnormal (and likely cause)

Answer 7

normal: able to follow target thru full range

abnormal: dec mobility in eye
- CN III, IV, VI lesion
- potential lesion of parietal/occipital lobe, pons, cerebellum

Question 8

what does smooth pursuits measure

Answer 8

person’s ability to accurately track a visual target in a smooth controlled manner
- looking for coordination

Question 9

what is the task for smooth pursuits

Answer 9

single point target held parallel to ground 18-24in from eyes
- person follows single point target as slowly moves horizontally and vertically

Question 10

smooth pursuits: normal vs abnormal (and likely cause)

Answer 10

normal: accurately track visual target in smooth controlled manner w both eyes
- eyes remained fixated on moving object

abnormal: eye mvmt not controlled
- consistent saccadic intrusions
- GEN (closer to end range)

(+) central dysfunction

Question 11

what are saccades

Answer 11

normal rapid, ballistic mvmts of eyes that abruptly change point of fixation
- amplitude of mvmt changes depending on task

Question 12

how are saccades tested/assessed

Answer 12

person repeatedly change gaze fixation from one target to another
- assessed both horizontally and vertically

Question 13

saccades: normal vs abnormal (and likely cause)

Answer 13

normal: eyes should be conjugate, have normal amplitude and brisk velocity

abnormal: consistently overshoots (hypermetric) or undershoots (hypometric) w multiple small saccades to get to target

*(+) central path

Question 14

what is vergence and how is it tested

Answer 14

simultaneous mvmt of both eyes in opposite directions to obtain or maintain single binocular vision

person focuses on tip of finger while slowly moves toward pt nose

Question 15

vergence: normal vs abnormal (and likely cause)

Answer 15

normal: eyes should converge symmetrically and pupils should constrict
- NPC <4’’

abnormal: eye mvmt asymmetrical
- NPC >4’’

*(+) indicate central path
- some people show ocular deviation at baseline, 6% of gen pop has convergence insufficiency

Question 16

what is spontaneous nystagmus

Answer 16

nystagmus at rest w fixed gaze

Question 17

why are frenzel lenses a good tool to utilize when testing for spontaneous nystagmus

Answer 17

help to block out light
- makes it so pt can’t fixate on object to suppress nystagmus -> CNS can suppress peripheral causing spontaneous nystagmus by fixating on target

also makes eyeballs larger to more accurately identify mvmt

Question 18

what is spontaneous nystagmus a key clinical sign in

Answer 18

pts w acute vestibular syndrome (AVS)

Question 19

what are causes of spontaneous nystagmus and what are ways to diff dx

Answer 19

acute unilateral peripheral hypofunction
- dec w gaze fixation
- resolves w/i 3-7days

central lesion (brainstem, cerebellar abnormality)
- doesn’t dec w gaze fixation
- doesn’t resolve w/i days and is chronic in nature

Question 20

what is rebound nystagmus

Answer 20

keeps going back and forth w/o a slow or fast beat phase

Question 21

how is GEN/holding nystagmus assessed

Answer 21

watch pt in primary gaze and then in lateral gaze (usually 30deg to each side)
- assess direction and # of beats

Question 22

GEN: normal vs abnormal

Answer 22

normal: <1-2 beats in end range
- present in >50% of gen pop w normal vision
- GEN normal in people >65yo bc eye ms lose ability to tonically hold end range

abnormal: sustained GEN > 2 beats

Question 23

GEN of a central vs peripheral origin

Answer 23

central: dominant characteristic is direction changing nystagmus, pure vertical/torsional
- could be rebound

peripheral: consistently beats away form affected side (toward intact side)
- non-direction changing
- can be torsional
- may be suppressed w gaze fixation

Question 24

what is VOR cancellation and how is this assessed

Answer 24

in order to shift direction of gaze along w head motion, VOR needs to be overridden/cancelled

assess person’s ability to maintain fixation on target while head and target are moving

Question 25

VORc: normal vs abnormal (and likely cause)

Answer 25

normal: can maintain visual fixation w/o c/o blurriness abnormal: saccadic eye mvmts/intrusions (eyes move off target, eyes jump back to target) - person c/o blurriness *(+) central dysfunction

Question 26

what are tests for the VOR and what do abnormal results of these tests usually indicate

Answer 26

head thrust/impulse test head shaking induced nystagmus dynamic visual acuity unilateral vestib hypofunction - aka peripheral dysfunction

Question 27

indication of CNS vs PNS involvement in abnormal VOR findings

Answer 27

CNS = vertical nystagmus PNS / vestib hypofunction - horizontal nystagmus - beat away from affected side

Question 28

dynamic visual acuity: normal vs abnormal (and likely cause)

Answer 28

normal: 2-line or less difference b/w static and dynamic visual acuity abnormal: UVH >3 line loss BVH > 5 line loss

Question 29

how is the head thrust/impulse test helpful for diff dx

Answer 29

helpful to r/o stroke d/t high specificity/sensitivity to detect vestib hypofunction

Question 30

what are 2 important considerations in performing a head thrust / impulse test

Answer 30

head flex forward 20-30deg to level horizontal canals high acceleration thrusts to kick in VOR

Question 31

head thrust: normal vs abnormal (and likely cause)

Answer 31

normal: vision fixation maintained abnormal: corrective saccades after head rotation inability to maintain visual fixation (+) peripheral hypofunction on side head turned toward during testing - (+) thrust R, corrective L saccade = R UVH - (+) thrust R and L = BVH

Question 32

what is an important consideration if you want to perform a head shaking induced nystagmus test

Answer 32

only performed w fixation blocked (ie Frenzel lenses)

Question 33

procedure for head shaking induced nystagmus test

Answer 33

head flex down 30deg, eyes closed, head rapidly oscillated by PT 20xs - cued to open eyes just prior to stopping head motion and observe for nystagmus

Question 34

head shaking induced nystagmus: normal vs abnormal (and likely cause)

Answer 34

normal: none or 1-2 beats abnormal: >/= 3 beats - existing nystagmus accentuated - usually beats to intact side

Question 35

what do the presentations of head shaking induced nystagmus indicate

Answer 35

beats L = R UVH beats R = L UVH vertical nystagmus = central vestib