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Vestibular I > Week 1 - Review & Intro > Flashcards

Week 1 - Review & Intro Flashcards

1
Q

What are the three categories of testing included in the ENG/VNG battery?

A
  1. Oculomotor Testing
  2. Positional/Positioning Testing
  3. Caloric Testing
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2
Q

What is included in oculomotor testing?

A

Calibration
Gaze
Saccade
Smooth Pursuit
OPK/OKN

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3
Q

What is included in Positional/Positioning Testing?

A

Calibration
Positional Testing
Positioning Testing

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4
Q

What is included in Caloric Testing?

A

Calibration
Caloric stimulation

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5
Q

What are the two primary functions classes of eye movements?

A
  1. Holding images steady on the retina
  2. Directing the foveae to an object of interest
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6
Q

What tests are performed to assess the ability to hold an image steady on the retina?

A

Visual fixation
Vestibular
Optokinetic (OPK, OKN)

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7
Q

What tests are performed to assess the ability to direct the foveae to an object of interest?

A

Saccades
Nystagmus fast phases
Smooth pursuit
Vergence

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8
Q

What are the circuit levels of the oculomotor system?

A
  1. Lower Level (Output)
  2. Middle Level
  3. High Level
  4. Calibration and Repair
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9
Q

What are the lower level circuits?

A

Orbit and Globe
Extraocular Muscles
Cranial Nerve Nuclei

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10
Q

What are the middle level circuits?

A

Version circuits
Vergence circuits
Neural Integrator

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11
Q

What are the high level circuits?

A

Saccades
Pursuit and OKN
Fixation
Vestibular

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12
Q

What is the calibration and repair circuit?

A

Cerebellum

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13
Q

What are the appropriate conditions of oculomotor testing for gaze, saccade, smooth pursuit, and OPK/OKN?

A

Sitting upright
Following the light (without moving the head)
Voluntary, volitional eye movements
Must be alert

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14
Q

What would abnormal findings during oculomotor testing indicate?

A

Usually central findings if pharmacological effects and fatigue are ruled out

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15
Q

What is GAZE?

A

“stare” or “fixate” at a non-moving target; holds image steady on retina
Center
Right
Left
Up
Down

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16
Q

What assesses gaze?

A

Visual fixation

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17
Q

How should the graph look for typical gaze testing results?

A

Straight horizontal lines.
Top line, blue = Horizontal gaze
Bottom line, red = Vertical gaze

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18
Q

How does the graph look for abnormal gaze testing results?

A

Horizontal line
Rises up
Nystagmus
Drops down
Slower nystagmus

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19
Q

What is endpoint nystagmus?

A

Occurs with eccentric gaze (away from primary position)

Happens in normal subjects

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20
Q

What circuit level is visual fixation?

A

High Level

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21
Q

What are SACCADES?

A

Directs the foveae to an object of interest

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22
Q

What is the circuit level for saccades?

A

High Level

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23
Q

How do you analyze saccades?

A

Evaluate:
Accuracy
Latency
Peak Velocity

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24
Q

What causes abnormal saccade patterns?

A

Ocular dysmetria
Abnormal velocity
Abnormal latency
Disconjugate eye movements

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25
Q

What is ocular dysmetria? What are the two types?

A

Inability to control distance, speed, and range of motion for smooth coordinated eye movements

I. Hypermetric (overshoot)
II. Hypometric (undershoot)

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26
Q

What are two conditions that cause disconjugate eye movements?

A

Internuclear Ophthalmoplegia (INO)

One-and-Half Syndrome

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27
Q

What is INO?

A

Internuclear Ophthalmoplegia

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28
Q

What is One-and-Half Syndrome?

A

Syndrome characterized by horizontal movement disorders of the eyeballs

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29
Q

What does ocular dysmetria assess?

A

Accuracy

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30
Q

What is hypertremia?

A

Eyes overshoot the target

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31
Q

What causes hypermetria?

A

Cerebellar dorsal vermis

Must rule out:
Vision loss
Blinking
Improper calibration

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32
Q

What is hypotremia?

A

Eyes undershoot the target

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33
Q

What causes hypotremia?

A

Cerebellar impairments, INO, supranuclear palsy, basal ganglia disorders

Must rule out:
Vision loss (macular degeration)
Fatigue
Medication
Lack of alertness
Blinking

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34
Q

What is normal saccade velocity?

A

Greater than 88 deg/sec at 20 deg eye movement

~.15 at 20 deg refixation
Larger saccadic refixations: FASTER
Smaller saccadic refixations: SLOWER

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35
Q

What are two categories of abnormal saccade velocity?

A

Slow Saccades
Fast Saccades

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36
Q

What are the site of lesions that cause slow saccades?

A

PPRF
MLF
Superior Colliculus
Cortex

Must rule out:
Drowsiness
Intoxication

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37
Q

What are the possible causes for fast saccades?

A

Mass or trauma to eye
Cerebellar impairments
Brainstem impairments

Must rule out:
Technical problems (calibration, eye range of motion)

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38
Q

What are the two categories of abnormal latency?

A

Late Initiation
Early Initiation

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39
Q

What affects late initiation latency?

A

Age
Alertness
Inattention
Visual impairment
Degenerative disorders

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40
Q

T/F: Abnormal latency has limited clinical utility on its own

A

True - must support other test results to confirm disorder

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41
Q

How do you correct early initiation latency?

A

Reinstruction

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42
Q

What is SMOOTH PURSUIT?

A

Directs foveae to a object of interest
Allows us to follow a moving target
Stabilizes a moving target on the foveae

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43
Q

What circuit level is pursuit?

A

High level

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44
Q

How do saccades look on the graph?

A

Black line: target
Blue line: eye movements

Should match as close as possible; some latency is normal. Close match = high accuracy

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45
Q

How does normal smooth pursuit look on a graph?

A

Horizontal Eye Position: waveform, lines overlap/match well

Tracking Gain: evenly spaced, high velocity; above the abnormal grey range; mirror image

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46
Q

How does abnormal smooth pursuit look on a graph?

A

Horizontal Eye Position: cog-wheel pattern
Tracking Gain: uneven spacing of dots, low velocity; in abnormal range

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47
Q

T/F: Smooth pursuit system is involuntary

A

False - voluntary control

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48
Q

What is the most common causes of impaired pursuit?

A

Pharmacology
Fatigue

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49
Q

T/F: We cannot “track” smoothly unless there is a smoothly moving target

A

True

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50
Q

What does pursuit abnormality indicate?

A

Not clinically robust!
Affected by lots of things!
-inattention, fatigue, sedation, inability to follow direction, age

If all ruled out:
Cerebellar lesion likely

51
Q

What is optokinetic tracking?

A

Assesses optokinetic nystagmus

52
Q

What is optokinetic nystagmus?

A

Combination of saccadic (eyes jump to target) and pursuit eye movements (track target movement)

Provides minimal diagnostic information on ENG

Poor stimulus

53
Q

T/F: Optokinetic nystagmus symmetry is not affected by spontaneous nystagmus

A

False, it does!

54
Q

What tests optokinetic nystagmus?

A

OPK, OKN

55
Q

Describe OPK/OKN testing.

A

Visually mediated sense of self motion (requires full visual field movement)
Responsible for detecting SLOW head/body motion
Assumes the world does not move
More robust than smooth pursuit

56
Q

What neural structures are involved in OPK with a small stimulus?

A

MT
MST
Pontine nuclei
Essentially the same pathway as pursuit

57
Q

What neural structures are involved in OPK with a full-field stimulus?

A

Nucleus of optic tract (NOT)
Pontine nucleus
Bypasses cortex

58
Q

What is NOT?

A

Nucleus of optic tract
Responds only to ipsilateral stimuli

59
Q

How does stimulus matter with OPK?

A
60
Q

Why is symmetry important?

A

TBD -
Spontaneous nystagmus

61
Q

What are the two categories of fixation suppression?

A

Saccadic eye movements
Slow eye movements

62
Q

Saccadic Eye Movements

A

aka square wave jerks

Internally generated “noise” without specific localization (but in high level)

63
Q

What mediates fixation suppression of saccadic eye movements?

A

Saccadic System
Superior Colliculus

64
Q

Slow Eye Movements

A

E.g. Vestibular Mediated Nystagmus

65
Q

What partially mediates fixation suppression of slow eye movements?

A

Pursuit System

66
Q

What are Positional Tests?

A

Static
Effect of the head position on nystagmus (eye movements)
Eyes are closed/covered + task

67
Q

What are Positioning Tests?

A

Dynamic
Effect of the head movement on nystagmus (eye movements)
Eyes are open and fixate

68
Q

What is the single most important test for diagnosing BPPV?

A

Dix-Hallpike Maneuver (dynamic positioning test)

69
Q

BPPV has what kind of nystagmus?

A

Transient, but severe nystagmus

70
Q

What are the characteristics of BPPV?

A

Latency of onset: 2-10 sec but can be delayed as much as 40 sec

Duration of nystagmus: 5-30 sec

Nystagmus is transient; declines slowly and subsides within a minute

Accompanied by vertigo

Response habituation / fatiguable

71
Q

Canalithiasis

A

otoconia (debris) float freely within the endolymph of the affected semicircular canal

72
Q

Cupulolithiasis

A

otoconia (debris) settle on or adhere to the cupula of the affected semicircular canal

73
Q

How do you perform a static positional test?

A

Sitting up right / Spontaneous
Supine
Head right
Head left
(Body right / right lateral)*
(Body left / left lateral )*
Head hanging center
30 deg incline (from horizontal plane)

*only if nystagmus is nystagmus is present with head right/left to rule out that nystagmus is caused by neck rotation

74
Q

Spontaneous Nystagmus

A

Should be tested immediately after gaze testing

IF nystagmus is observed:
describe nystagmus by direction and horizontal/vertical components

Is nystagmus suppressed by fixation?

75
Q

Positional Nystagmus

A

IF observed:
describe nystagmus by direction, amplitude, horizontal/vertical components, and duration of nystagmus (persistence)

Is it suppressed by fixation?

Does the direction change between positions or within a single position?

76
Q

T/F: Positional nystagmus is non-localizing by itself

A

True

77
Q

What are the patterns of nystagmus?

A

Right beating
Left beating
Geotropic
Apogeotropic
Ageotropic
Rotary/Torsional

78
Q

Geotropic

A
79
Q

Apogeotropic

A
80
Q

Ageotropic

A
81
Q

Right beating

A
82
Q

Left beating

A
83
Q

Rotary / Torsional

A

Clockwise
Counter clockwise

84
Q

What is the goal of lateral (side-lying) position testing?

A

Differentiate head position effects from neck rotation effects

Follow-up test to head right and head left positions

85
Q

Caloric Testing

A

Vision denied
Task
Dark room
250 cc
Fixation light (if nystagmus is observed)
5 mins between irrigations
total 4 irrigations

86
Q

Bithermal vs Monothermal

A
87
Q

What is the temperature for water irrigation?

A

7 deg Celsius above and below body temperature (37 deg C)

Warm: 44 C
Cool: 30 C

88
Q

What is the temperature for air irrigation?

A

13 degrees Celsius above and below body temperature (37 deg C)

Warm: 50 C
Cool: 24 C

89
Q

Ice Water Calorics

A
90
Q

Caloric Irrigation Options

A

Open-Loop Water
Closed Loop Water
Airx

91
Q

Set up: Caloric Irrigation

A

Head inclined 30 deg from horizontal plane
Vision denied
Task

92
Q

Caloric Irrigation - Irrigation Time

A

50 sec (ideal)
30 sec (ok with water if flow rate is increased)

93
Q

Caloric Irrigation - Recording Time

A

At least 1 min following the end of irrigation

94
Q

Why do we record a minute after the end of irrigation?

A

Peak velocity occurs at 30-40 sec post-irrigation

95
Q

Caloric Irrigation - Patient Instructions

A

What you’ll be doing and what they’ll experience:
-water in each ear
-temperatures of water
-duration of irrigation
-duration of recording

What you want them to do:
-eyes open (VNG) or closed (ENG)
-talk (tasking)
-don’t jump when water starts!

Reasons

96
Q

What do you avoid doing to minimize patient anxiety?

A

AVOID:
you will get dizzy
hot water
cold water
moving through steps without explaining

DO:
You may feel like you’re turning
Warm water
Cool water

97
Q

How should you instruct to minimize patient anxiety?

A

Describe everything that you’re doing that the patient cannot see:
Now I’m looking in your ear
I’m placing the basin underneath your ear
This is the tip that will deliver water into your ear
I will start the water on the count of three

97
Q

Unilateral Weakness (UV) /
Reduced Vestibular Response (RVR)

A

Ear difference (right EAR vs left EAR)
Define weaker ear

97
Q

Directional Preponderance

A

right BEATING vs left BEATING
Define stronger beating direction

98
Q

What do you look for in caloric irrigation response?

A

Unilateral Weakness (UV)
Reduced Vestibular Response (RVR)

Directional Preponderance

Gain Asymmetry

99
Q

Gain Asymmetry

A

Directional preponderance (DP) change corrected for spontaneous nystagmus

100
Q

What is the formula for unilateral weakness?

A

(RW+RC) - (LW+LC) divided by RW+RC+LW+LC x 100%

101
Q

What is the formula for directional preponderance?

A

(RW+LC) - (LW+RC) divided by RW+RC+LW+LC x 100%

102
Q

What is the norm for bilateral RVRs?

A

Total SPEV of all 4 irrigations less than or equal to 20 deg/sec

103
Q

What is considered a hyperactive caloric response?

A

Total SPEV > 300 deg/sec

104
Q

What do you do first when you notice an extremely rare abnormality?

A

Rule out technical errors!

105
Q

(Extremely) Rare Abnormalities

A

Caloric Inversion
Caloric Perversion
Premature Caloric Reversal
Caloric Dysryhthmia

106
Q

Caloric Inversion

A

[DEFINITION]
In all 4 irrigations
Caused by: posterior fossa lesions

107
Q

Caloric Perversion

A

[DEFINTION]
Purely vertical nystagmus
Vestibular nuclei; horizontal canal w/ normal vertical canals; NORMAL

108
Q

Premature Caloric Reversal

A

Reversal of nystagmus earlier than anticipated

Overadaptation in the vestibular nuclei?

Patients with Friedreich’s ataxia

109
Q

Caloric Dysrhythmia

A

Inconsistent variability in SPV
Caused by: fatigue, inattention

110
Q

Test Conditions: GAZE

A

Room Lighting: dark or light
Vision: Yes
Task: No

111
Q

Test Conditions: Saccade

A

Room Lighting: dark or light
Vision: Yes
Task: No

112
Q

Test Conditions: Tracking

A

Room Lighting: dark or light
Vision: Yes
Task: No

113
Q

Test Conditions: OPK

A

Room Lighting: dark
Vision: Yes
Task: No

114
Q

Test Conditions: Positional

A

Room Lighting: dark
Vision: denied
Task: yes

115
Q

Test Conditions: Positioning

A

Room Lighting: dark or light
Vision: yes / denied
Task: no

116
Q

Test Conditions: Calorics

A

Room Lighting: dark
Vision: denied
Task: yes

117
Q

What is the purpose of ice water irrigation?

A
118
Q

Ice Water Irrigation

A

4-5 cc saline in cup of ice water
Hold in ear canal for 30 sec
Caloric position
Prone position

119
Q

What should happen during ice water irrigation?

A

Should reverse nystagmus direction in prone position

120
Q

[UNK] Monothermal Testing

A

Which temperature?
Calculations for asymmetry
Effects of baseline on DP and monothermal calculations

121
Q

How do you explain caloric pod/figures?

A

Calculate RVR, DP, and GA as applicable
Validity of irrigations?
Other issues? (how did you resolve, or would you?)

What other VNG findings (abnormalities) might you see during oculomotor and positional tests?

Can you make some diagnoses?
-peripheral, central
-laterality
-compensation status

121
Q

Monothermal Screening

A

No abnormalities in an VNG subtests
Each warm irrigation is 11 deg/sec or greater
Monothermal difference is < 10%
Normal FI

Vestibular I (3 decks)

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