Final Rotary Chair,SHA,SV,Vfx,VVOR,AHR

Question 1

Slow phase is driven by what

Answer 1

Slow phase is driven by the ears (peripheral vestibular)

Question 2

Fast phase is driven

Answer 2

Fast phase is driven by the CNS (central)

Question 3

Nystagmus beats towards

Answer 3

Nystagmus beats towards the stimulated ear

Question 4

Nystagmus beats away

Answer 4

Nystagmus beats away from an inhibited/affected ear

Question 5

Describe the vestibular audiogram

Answer 5

Very Low F: Calorics
Low & Mids: Rotary Chair & hit
High F: Active head rotation

Question 6

What are the two types of rotation tests?

Answer 6

Active & Passive

Question 7

The patient move their own head

Answer 7

Active

Question 8

Active Rotation Example

Answer 8

Vestibulo-autorotation test (VAT/Vorteq)
&
Headshake can be active or passive

Question 9

Define Active RT

Answer 9

The patient move their own head

Question 10

The patient is moved (head or whole body) by the examiner

Answer 10

Passive

Question 11

Passive Rotation example

Answer 11

Halmagyi Head Thrust (HIT),
Rotary Chair Tests,
Off-axis rotations (SVV and SVH)

Question 12

Define Passive RT

Answer 12

The patient is moved (head or whole body) by the examiner directly

Question 13

Rotary Chair Evaluation Parameters

Answer 13

gain, symmetry & phase

Question 14

Why is It unwise to test only one slow velocity

Answer 14

VOR functions at a wide range of velocities and to only test one and generalize would not be an accurate picture.

Question 15

Pros of Rotary testing

Answer 15

Rotary testing is a more natural speed of head movement/ VOR function & more tolerable than calorics

Question 16

Where is the axis of rotation?

Answer 16

The axis of rotation for rotary chair is centered between both labyrinths (bilateral stimulation)

Question 17

CCW rotations

Answer 17

CCW rotations = left-beating nystagmus
- (left HSCC excitatory, right HSCC inhibitory effect)
- CCW is rotating to left

CCW - couterclock wise

Question 18

CW rotations

Answer 18

CW rotations = right-beating nystagmus
* (right HSCC excitatory, left HSCC inhibitory effect)
* CW rotatess to the right

Question 19

Rotatary Chair focus on what phase?

Answer 19

RC ONLY Focuses on Slow phases of nystagmus
* Fast phases are tossed out for analysis .
* All slow phases are then combined in a sinusoidal form for analysis.

Question 20

Rotary chair can be used to examine the

Answer 20

Rotary chair can be used to examine the HSCC, central systems and vestibular nuclei.

Question 21

Clinical application of rotary chair

Answer 21

• Evaluates bilateral vestibular loss (BVL); or patient w/ low calorics
• monitor for ototoxicity (vestibulo-toxicity)
• evaluate for CNS disorders
• Tells us degree of Central compensation
• guides Rehab therapy decisions
• evaluate vestibular function on those who can’t undergo caloric testing or w/ calorics that can’t be reliably compared

Question 22

SHA stands for

Answer 22

Sinusoidal Harmonic Acceleration

Question 23

SHA procedure

Answer 23

• velocity of 60 deg/s @ various freq
• Octave of .01-1.28
• 2-3 cycles for each freq
• start MF,HF then LF
• IN Darkness
• Must Task

Question 24

SHA (VOR) Measurement Parameters:

Answer 24

Gain: eye movements relative to chair (head) movement
* Gain measured @ <.15 = no calc is made

Symmetry: difference b/w peak right beating and peak left bearing divided by sum of SPV (slow phase velocity)
* Most common in those with spontaneous nystagmus

Phase: compares timing of peak eye velocity to peak chair velocity
* most valuable, indirect measure of velocity storage mechanism

Spectral Purity: How clean the data is
* any artifact?

Question 25

# SHA Normal or Abnormal?

Answer 25

Normal

Question 26

Step Velocity examines what

Answer 26

The vestibular system’s central velocity storage

Question 27

Step Velocity Procedure

Answer 27

* Patient is quickly accelerated to a constant velocity and rotated in one direction (CW or CCW) for about 1 minute * Typically velocity used is either 60, 100 or 200 deg/s * Velocities > 200 deg/s= more ear-specific * stopped abruptly and post-rotary nystagmus observed for about 1 minute * repeated for the opposite direction (CW or CCW) * pre & post-rotary nystagmus are compared Abnormal gain or duration patterns (called time constants) suggest specific deficits in the vestibular system

Question 28

Step Velocity Test

Answer 28

* Performed in complete darkness with tasking * Initial stimulation should show a burst of nystagmus beating **toward** the direction of rotation * nystagmus will dispear over time as the subject maintains constant velocity * stopped and their will be a second burst of nystagmus but in opposite direction Both the gain and duration of the per-rotary and post-rotary nystagmus are measured Summary * Darkness - rotate = burst N - Nysta stops since rotation constant - Stopped = burt N but opposite

Question 29

Step Velocity Measurement Parameters:

Answer 29

**Gain** = Initial peak gain SPV of nystagmus * Measured pre & post-rotary Reduced gain = Central, bilateral or unilateral vestibular disorders * Greater rotational velocities (>200 deg/s) = more ear-specific (due to larger excitatory response) **Time Constant** = Time required for nystagmus to decay to 37% of original peak gain SPV * Measure pre & post-rotary * Variable dependent on velocity of chair * > 10 seconds = normal shortened time constants = Central, bilateral or unilateral vestibular disorders

Question 30

Step Velocity Reduced gain

Answer 30

Central, bilateral or unilateral vestibular disorders

Question 31

Time required for nystagmus to decay to 37% of original peak gain SPV

Answer 31

Time Constant

Question 32

# Step Velocity shortened time constants

Answer 32

shortened time constants = Central, bilateral or unilateral vestibular disorders

Question 33

Normal time constant (sec)

Answer 33

Greater/equal to 10 seconds = normal

Question 34

Patient is asked to fixate on a point of light projected in front of them on the enclosure wall while being rotated sinusoidally. Visual target travels at same speed as chair.

Answer 34

Visual Suppression (Fixation) VFx:

Question 35

Visual Suppression (Fixation) VFx

Answer 35

* fixate on point while being rotated in the chair sinusoidally. (visual is same speed as chair) * Should be able to maintain focus on the light which will reduce the vestibular induced nystagmus. * Failure to fixate = central sign (occipital, parietal lobe or flocculus of cerebellum) * No tasking because there is a target * Ensure good vision

Question 36

# VFx Failure to fixate =

Answer 36

Failure to fixate = central sign (occipital, parietal lobe or flocculus of cerebellum)

Question 37

Performed by projecting the OPK stimulus onto the wall of the rotary chair enclosure Patient is rotated sinusoidally much like the VFx test but the OPK stimulus is stationary (does not move with the chair)

Answer 37

Visual Enhancement (VVOR):

Question 38

Visual Enhancement (VVOR):

Answer 38

* Performed by projecting OPK stimulus on wall of rotary chair enclosure. * patient is rotated sinusoidally and OPK stimulus does not move. * Pursuit, OPK, and VOR systems contribute. * **Test is done if the patient has low gain for traditional SHA tests**.

Question 39

Rotational Chair Limitations:

Answer 39

* Tests VOR at low & mid frequencies * Only shows Function of HSCC and SVN, + CNS & VN (no info about function of otoliths, IVN, or other SCC’s * Can’t perform on claustrophobic or obese patients. * poor ear specificity, will miss mild-moderate unilaterallosses

Question 40

* lower cost, easy-to-use, more space efficent tool to measure the VOR during rapid head movements where visual stability might be impaired in a patient with a vestibular (VOR) deficit * assess moderate to high frequency head movements not adequately addressed by rotary chair and provide a fuller representation of head movement and functional limitations experienced by patients at a substantially lower cost

Answer 40

Active Head Rotation Test (AHR)

Question 41

Active Head Rotation (AHR) Procedure

Answer 41

* Goggles * Metronome * Patient would actively shake their head “yes” and “no” to the beat of a metronome over a specified frequency range * Could also be performed with Dynamic Visual Acuity Test (DVA or DVAT)

Question 41

Active Head Rotation Test (AHR)

Answer 41

* Used to measure VOR during rapid head movement where visual stability might be impaired in a patient with VOR deficit. * assesses moderate - high frequency movements not assessed by rotary chair * Cheaper

Question 42

Active Head Rotation measurement

Answer 42

Gain, phase parameters

Question 43

AHR: compares & assess what?

Answer 43

* compares eye movements induced by active motion of the head * assess mid to high frequencies. rotary chair is low - mid frequencies

Question 44

AHR freq range

Answer 44

range 2 to 6 Hz * Central oculomotor system can only move eyes at frequencies 1-2 Hz. * To make sure you are assess peripheral it needs to be above 2 Hz

Question 45

AHR limits

Answer 45

* goggles slip and can cause HF phase to be wrong * Test-retest is insufficient * Overestimate vestibular function because they have contributions from neck or higher cortical function * No code to bill