Vestibular Hypofunction

Question 1

What are the two types of vestibular hypofunction?

Answer 1

UVH-unilateral vestibular hypofunction

BVH-bilateral vestibular hypofunction

Question 2

What are the three tests that test vestibular hypofunction?

Answer 2

Head Thrust Test (HTT)
Head Shaking-Induced Nystagmus Test (HSN)
Dynamic Visual Acuity Test (DVA)

Question 3

What does the Head Thrust Test (HTT) Examine?

Answer 3

for UVH and BVH

Question 4

How do you perform the Head Thrust Test(HTT)?

Answer 4

patient’s head flexed 30 degrees to bias H-SCC’s and focuses eyes on clinician’s chin; then perform passive unpredictable small amplitude rapid head thrusts away from midline

Question 5

What is a positive Head Thrust Test(HTT)?

Answer 5

positive test is corrective saccades; direction of HTT that produces corrective saccade is side of dysfunction due to vestibular hypofunction; for example, if corrective saccade is produced during left HTT, result is documented as a positive (L) HTT suggesting left UVH

Question 6

What does the Head Shaking-Induced Nystagmus Test (HSN) examine?

Answer 6

for UVH and BVH

Question 7

How is the Head Shaking-Induced Nystagmus Test (HSN) performed?

Answer 7

patient’s head flexed 30 degrees to bias H-SCC’s and focuses eyes on clinician’s chin then closes eyes; then passively rotate patient’s head back and forth at speed of approximately 2 cycles per second for 10 seconds; patient asked to open eyes prior to last 2-3 passive rotations and instructed to focus on clinician’s chin

Question 8

What is a positive Head Shaking-Induced Nystagmus Test?

Answer 8

positive test is >3 beats of nystagmus; slow phase is side of hypofunction but condition is named by fast phase due to velocity storage mechanism and asymmetrical firing rate of vestibular nuclei; for example, if fast phase is to patient’s right, it’s documented as a right-beating nystagmus suggesting left UVH

Question 9

What does the Dynamic Visual Acuity Test(DVA) examine?

Answer 9

for UVH and BVH

Question 10

How is the Dynamic Visual Acuity Test(DVA) performed?

Answer 10

patient seated at appropriate distance from ETDRS chart and instructed to read lowest line possible (static visual acuity), clinician then passively rotates patient’s head from side to side at frequency of approximately 2 cycles per second and asks patient to read lowest line possible (dynamic visual acuity)

Question 11

What is a positive Dynamic Visual Acuity Test(DVA)?

Answer 11

positive test is loss, or drop, of more than 2 lines; for example, if patient’s statically reads lines 6, but dynamically cannot read line 6, line 5, or line 4; but can read line 3, the test is positive; alternatively; if patient were able to read line 4 during the same example, the test would be negative

Question 12

While performing the HSN patient demonstrates slow phase nystagmus to the left how is this documented?

Answer 12

Right-beating nystagmus
suggesting left UVH

Reasoning: slow phase is side of hypofunction but condition is named by the fast phase

Question 13

Patient produces corrective saccades during left HTT how is this documented?

Answer 13

result is documented as a positive (L) HTT suggesting left UVH

Question 14

UVH or BVH is suspected in patient, therefore you perform the HSN. While performing the HSN patient demonstrated fast phase nystagmus to the right. How would you document this?

Answer 14

Results would be documented as RIght-Beating Nystagmus

this would suggest left UVH

Question 15

You perform the HTT on your patient. You observe corrective saccades to their right. How would you document this?

Answer 15

result is documented as a positive (R) HTT suggesting right UVH

Question 16

If patient has UVH or BVH what exercises would you suggest?

Answer 16

adaptive exercises x1 and x2

Question 17

What is the sequence for Adaptive exercise X1 simple version

Answer 17

sit upright in arm chair
hold letter E @ eye level with plain white background
keep eyes focused on letter E
rotate head smoothly from side to side for 15 seconds
letter E should be relatively focused during exercise
symptoms should increase 1-2 points during exercise
symptoms should return to baseline within 1-5 minutes
perform once daily as able

Question 18

How can you alter Adaptive exercise X1 to make it more difficult?

Answer 18

change the plain white background to a busy background
increase time
increase distance of E
Increase frequency

Question 19

What is the sequence for Adaptive exercise X2 simple version

Answer 19

sit upright in arm chair
hold letter E @ eye level with plain white background
keep eyes focused on letter E
rotate head smoothly from side to side for 15 seconds while moving letter E in opposite direction
letter E should be relatively focused during exercise
symptoms should increase 1-2 points during exercise
symptoms should return to baseline within 1-5 minutes
perform once daily as able

Question 20

How can you alter Adaptive exercise X2 to make it more difficult?

Answer 20

change the plain white background to a busy background
increase time
increase distance of E
Increase frequency