Block 10 > mono: electrodiagnostics > Flashcards

mono: electrodiagnostics Flashcards

(74 cards)

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1
Q

What are the 3 types of electrodiagnostics?

A

Electrooculogram (EOG), Electroretinogram (ERG), Visual Evoked Potential (VEP)

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2
Q

What are the 3 subtypes of ERG?

A

Full-field ERG, Pattern ERG, Multifocal ERG

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3
Q

What subtype of VEP is the go-to for testing visual acuity?

A

Flash VEP

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4
Q

EOG measures the existing resting electrical potential between the _________ and ___________

A

Cornea and Bruch’s membrane

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5
Q

With EOG, the most valuable information is the comparison of amplitudes under ___________ and ____________ states called the _____

A

Light and dark-adapted

Arden Ratio

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6
Q

Arden ratio =

A

Light peak Amplitude / Dark trough Amplitude

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7
Q

What is the light peak in EOG?

A

Maximum EOG voltage during light adaptation

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8
Q

What is the dark trough in EOG?

A

Minimum EOG voltage during dark adaptation

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9
Q

The Arden Ratio describes the function of ________

A

RPE

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10
Q

The Arden ratio can be used in diagnosing ____________/_____________ dysfunction

A

Retinal/RPE

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11
Q

What is standing potential in an EOG?

A

Difference of potential between the anterior and posterior part of the eye

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12
Q

Standing potential indirectly measures the ___________________ potential of the RPE

A

Trans-epithelial

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13
Q

The light-insensitive component of the EOG is what?

A

Dark trough

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14
Q

Dark trough of EOG is dependent on the integrity of what?

A

RPE, cornea, lens and ciliary body

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15
Q

The light-sensitive component of the EOG is what?

A

Slow light rise of EOG

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16
Q

Slow light rise of the EOG is generated by depolarization of the __________________ of the RPE

A

Basal membrane

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17
Q

Is EOG performed monocularly or binocularly?

A

Binocularly

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18
Q

Should a patient be dilated or undilated when performing EOG?

A

Dilated

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19
Q

Where are the 3 electrodes placed for EOG?

A

Active (+) = inner canthi, Reference (-) = outer canthi, Ground = forehead

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20
Q

What does the patient do during the testing process for an EOG?

A

Patient shifts gaze repeatedly from left to right

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21
Q

What is measured in an EOG?

A

Amount of light passing through the pupil (Trolands)

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22
Q

EOG testing is performed under _________ and _________ adaptation states

A

Light and dark

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23
Q

Dark trough is the ____________ voltage amplitude in the __________

A

Minimal, Dark

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24
Q

Light peak is the ______________ voltage amplitude in the ____________

A

Maximal, Light

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25
Normal Arden ratio
>/= 1.80
26
Subnormal Arden ratio
1.65 to < 1.80
27
Severely subnormal or extinguished Arden ratio
<1.65
28
In what disease does ERG remain normal but EOG is abnormal?
Best's disease - Best vitelliform macular dystrophy
29
How does the macula appear in Best's Disease?
Fried-egg or egg-yolk
30
ERG measures the electrical activity of the _________ in response to what?
Retina, in response to a light stimulus
31
Is ERG a subjective or objective measure of retinal function?
Objective
32
What does the ERG help discriminate the functionality of?
Layers of the retina. More than just RPE
33
A-wave of ERG arises from the _____________
Photoreceptors
34
What does the B-wave of an ERG arise from?
On-bipolar cells and depolarization of the muller cells
35
What represents the 'ringing' in the neural transmission at the amacrine cell layer?
Oscillatory potentials
36
What does the C-wave of an ERG represent?
RPE
37
What does the D-wave of an ERG represent?
Off-bipolar cells
38
What does Full-Field ERG seek to do?
Maximally stimulate almost all photoreceptors simultaneously
39
What does FFERG use to integrate responses over the entire retina?
Ganzfield
40
Is ffERG useful for maculopathies?
Not useful
41
Identify each wave of the full-field ERG on slide 23
ERG: DA 0.01 = Rods and bipolar cells, ERG: DA 3.0 = Rods/cones and bipolar cells, ERG: DA 10 = Rods/cones and bipolar cells, ERG: DA oscillatory potentials = Amacrine cells, ERG: LA 3.0 = Cones and bipolar cells, ERG: LA 30 Hz flicker = Cones
42
Scotopic ERG is taken in what state?
Dark-adapted
43
Is patient dilated with scotopic ERG?
Often times yes
44
How does the scotopic ERG limit response to rods only?
Use of a dim blue stimulus
45
In regard to Scotopic ERG, a dark adapted recording of a dim red stimulus includes what responses?
Some cone and rod responses
46
Photopic ERG is conducted in what state?
Light adapted
47
A Photopic ERG uses what flash?
Bright flash
48
Is the patient dilated or undilated for Photopic ERG?
Either
49
Single flash Photopic ERG includes small wavelets known as ____________
Oscillatory potentials
50
30 Hz flicker for Photopic ERG is basically a string of ____________ waves
A-waves
51
FfERG is an integrated look at the function of the _____________________
Retina layers
52
Because ffERG is a look at the entire function of the retina layers, what problems would it best at detecting?
Problems like Retinitis Pigmentosa that affect entire classes of cells
53
Is ffERG good for focal lesions such as maculopathy?
No
54
Is ERG performed monocularly or binocularly?
Monocularly
55
What ERG subtype assesses many local ERG responses within central 30º?
Multifocal ERG
56
Multifocal ERG is good at detecting what dysfunction that ffERG might miss?
Dysfunction within the macula
57
What does Pattern ERG assess?
Macular retinal ganglion cell activity
58
How does the pattern ERG waveform present?
Three relatively equally spaced peaks
59
How does Best's disease appear on a ffERG and an EOG?
Normal on ffERG, Abnormal EOG
60
What does visual evoked potential (VEP) measure?
Electrical signal generated at the visual cortex in response to visual stimulation
61
VEP results depend on the integrity of the visual pathway including what?
Globe, Optic nerve, Chiasm, Tract, Radiations, Cerebral cortex
62
Visual cortex responses is dominated by what activity?
Central visual field
63
What is the only electrophysiologic test that assesses visual cortical activity?
VEP
64
What are the 3 wave pulses in VEP?
N75 wave: Negative pulse around 75 ms, P100 wave: Positive pulse around 100 ms, N135 wave: Negative pulse around 135 ms
65
Is the patient dilated or undilated for VEP?
Undilated
66
Is VEP a monocular or binocular test?
Monocular
67
Where are the 3 electrodes placed in VEP?
Active (+): inion/external occipital protuberance, Reference (-): central forehead, Ground: left temple or top of head
68
How do cortical problems manifest with VEP testing?
Reduced amplitudes, Increased latency
69
VEP testing should include at minimum ______ recording of each protocol
2 recordings
70
What can VEP be used for in children/non-verbal patients specifically?
Visual acuity in children or non-verbal patients
71
Flash VEP presents __________ _______ flashes of light
Brief white
72
Is Flash VEP is performed monocularly or binocularly?
Monocularly
73
Flash VEP measures the basic integrity of the __________ and ___________ pathway
Macula and visual
74
What types of pathology will present with abnormal VEP testing?
Optic nerve or cortical problems
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