VNG testing

Question 1

nystagmographyy (ENG/VNG)

Answer 1

most common test evaluation for dizziness, vertigo or imbalance as it assesses both central and peripheral components
-allows to be recorded with either electrodes or infrared video

Question 2

what are the 3 components that are included in an ENG/VNG

Answer 2

oculomotor evaluation, positional/positioning evaluation and caloric irrigation

Question 3

what are the 4 potential outcomes from a ENG/VNG

Answer 3

normal, central, non-localizing and peripheral

Question 4

limitations of a VNG

Answer 4

only telling us about the SCC function, superior vestibular nerve and the central vestibular pathway

Question 5

calibration for VNG

Answer 5

have the patient seated upright, place the goggles on and have the patient follow the dot on the screen with their eyes only
-it will go up, down, left and right and ensure they track it

Question 6

patients that may not have a good calibration include ….

Answer 6

dark eyes, makeup on, cataract surgery, lazy eye or glass eye

Question 7

oculomotor evaluation is recording the eye movements that are modulated. this section consists of …

Answer 7

position maintenance (gaze holding), saccades, pursuit (tracking) and optokinetic (OPK/OKN)

Question 8

all oculomotor evaluations indicate a ………

Answer 8

central finding however there are exceptions

Question 9

position maintenance (gaze holding)

Answer 9

consists of central, left, right, up and down positions
-we are identifying if there is nystagmus or not

Question 10

if there is nystagmus within gaze holding, this indicates …

Answer 10

a central finding UNLESS there is spontaneous nystagmus which then it would be non-localizing

Question 11

gaze holding steps

Answer 11

instruct the patient that the dot will be steady then will jump to a different place on the screen, have the patient follow that dot as it moves with their eyes only

Question 12

saccades

Answer 12

assessing the ability to track fast moving targets
-we are identifying the velocity, latency and accuracy of the nystagmus

Question 13

velocity of saccades

Answer 13

the peak speed of eye movement
-too slow can be seen with drug interaction or drowsiness
-too fast can be seen with calibration issues or with a noisy recording

Question 14

latency of saccades

Answer 14

the time to get on target
-prolonged is seen with uncooperative patients
-reduced is seen with technical errors or anticipation

Question 15

accuracy of saccades

Answer 15

the accuracy on the target location
-overshooting (hypermetric)
-undershooting (hypometric)
-both over and under shooting (dysmetria)

Question 16

if there is nystagmus within saccades, this indicates ….

Answer 16

a central finding

Question 17

saccade steps

Answer 17

instruct the patient to follow the target with their eyes only as it will jump around randomly on the screen

Question 18

pursuit (tracking)

Answer 18

horizontal and vertical movements with following an object
-identifying gain, phase and some include the number

Question 19

gain of pursuit

Answer 19

the eye movement relative to the target

Question 20

phase of pursuit

Answer 20

the symmetry between the eyes

Question 21

if there is nystagmus within pursuit, this indicates a ….

Answer 21

central finding
-sensitive for single sided or general damage

Question 22

pursuit steps

Answer 22

instruct the patient to follow along as the dot or light moves across the screen
-glide with it as it goes

Question 23

optokinetic (OPK/OKN)

Answer 23

elicited by the tracking of a moving field
-identifying the symmetry and gain of the nystagmus

Question 24

if there is an abnormal finding in OPK, this indicates a ….

Answer 24

central finding
-often correlated with pursuit

Question 25

positional/positioning evaluation involve either dynamic or static movements, this consists of ....

Answer 25

positional (dynamic) : dix-hallpike maneuver positioning (static) : supine head roll and potentially whole body roll

Question 26

dix-hallpike maneuver

Answer 26

test that is aimed for diagnosing BPPV within the anterior or posterior canal -identifying if there is torsional nystagmus present or not

Question 27

dix-hallpike maneuver reasoning

Answer 27

the movement allows for the endolymph to drop into the otoconia therefore placing something responsible for gravity into a place where it is not supposed to be

Question 28

dix-hallpike maneuver steps

Answer 28

-grab the patients head and shoulder -turn the head one direction at a 45 degree angle -rapidly take the patient down to a head hanging position and observe the eyes for torsional nystagmus -after at least 30 seconds, raise the patient

Question 29

dix-hallpike maneuver with torsional nystagmus indicates ...

Answer 29

if upward torsional it is posterior canal BPPV if downward torsional it is anterior canal BPPV

Question 30

dix-hallpike maneuver can be modified to a ....

Answer 30

side laying maneuver by rapidly moving the patient from center to the side

Question 31

supine head roll (center, left and right)

Answer 31

a test that assesses for horizontal canal BPPV by adjusting the head position when the patient is laying down

Question 32

supine head roll steps

Answer 32

lay the patient back and put into the center, right and left head position for at least 30 seconds

Question 33

in order for the nystagmus to be abnormal within the supine head roll, one of the following criteria needs to be met

Answer 33

-if the nystagmus changes direction with any head position -if the nystagmus is persistent in at least 3 head positions -if the nystagmus is intermittent in all positions -if the nystagmus has a slow velocity speed that exceeds 6 degrees/second in any position

Question 34

if there is nystagmus present in the supine head roll, this indicates ...

Answer 34

horizontal canal BPPV AND the need to go onto the whole body roll testing

Question 35

whole body roll

Answer 35

a test that allows us to test the inner ear without including the potential neck impact

Question 36

whole body roll steps

Answer 36

have the patient lay on the right side and the left side as if they were going to fall asleep -keep on each side for at least 30 seconds

Question 37

calorics is the most informative part of the VNG because ....

Answer 37

you are able to excite only one vestibular organ while the other stays at rest -identifying unilateral weakness, directional preponderance, fixation suppression and hyperactive/hypoactive responses

Question 38

unilateral weakness (caloric paresis)

Answer 38

comparing the slow phase velocity (SPV) of the left ear to the SPV of the right -comparing the strength between the two ears

Question 39

directional preponderance in calorics

Answer 39

comparing the SPV of eye movements in the same direction -using COWS to compare

Question 40

fixation suppression in calorics

Answer 40

observing if the nystagmus goes away or slows down with the addition of a fixation or not

Question 41

hyperactive/hypoactive responses in calorics

Answer 41

looking for a bilateral caloric weakness -adding up total eye speed

Question 42

temperatures for air and water (with times)

Answer 42

water: 30 and 44, recording for 30 seconds air: 24 and 50, recording for a minute

Question 43

expected response within calorics

Answer 43

COWS (cool opposite, warm same)

Question 44

how to record

Answer 44

place patient into caloric position (supine with head elevated at 30 degrees with vision denied), determine proper temperature is turned on, place caloric into ear and start recording, after the time has completed remove and instruct patient to open their eyes, repeat on the other side with the same temperature then different temperature coming back to the first ear last