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Ocular Motility > Nystagmus > Flashcards

Nystagmus Flashcards

1
Q

What is nystagmus?

A

abnormal fixation, rhythmic oscillation, congenital or acquired

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2
Q

Is nystagmus voluntary or involuntary?

A

involuntary

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3
Q

What are two properties describing nystagmus?

A

waveform and direction

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4
Q

What does acquired nystagmus show that congenital does not?

A

oscillopsia

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5
Q

What are the four waveforms?

A

pendular, jerk, gaze holding/latent-manifest, and vestibular

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6
Q

Describe pendular waveform

A

smooth back and forth, velocity similar in both directions, amp can vary

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7
Q

Describe jerk waveform

A

slow phase and quick re-fixation, gets faster as slow phase gets more eccentric

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8
Q

Describe gaze-holding/latent manifest waveform

A

type of jerk, gets slower as slow phase gets more eccentric

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9
Q

Describe vestibular waveform

A

steady velocity throughout

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10
Q

What is pendular nystagmus amp, frequency, and peak velocity?

A

0.5-10 degrees, 2-8 Hz, up to 100 deg/sec

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11
Q

T/F congenital pendular nystagmus is usually horizontal

A

true

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12
Q

What is congenital pendular nystagmus associated with?

A

albinism

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13
Q

Acquired nystagmus often has what direction?

A

vertical and torsional with more variability in waveform

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14
Q

What can cause acquired nystagmus?

A

myelin diseases, central brainstem stroke, monocular vision loss

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15
Q

Congenital nystagmus can fall into what two broad categories?

A

associated with detectable ocular anomaly OR no anomaly aka idiopathic

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16
Q

What percent of nystagmus patients have strabismus?

A

15%

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17
Q

What conditions are associated with ocular anomolies?

A

congenital cataracts, foveal hypoplasia, deprivation amblyopia, optic atrophy

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18
Q

What are the three basic types of jerk nystagmus?

A

congenital, gaze-evoked, vestibular

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19
Q

What is congenital jerk nystagmus?

A

arises during first year, horizontal and conjugate (both eyes move together), reduced with convergence, worsened with intentional monocular fixation

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20
Q

What is the amp, frequency, and slow phase velocity congenital jerk nystagmus?

A

0.25-5 deg, 1-5 Hz, up to 100 deg/sec

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21
Q

Do patients with congenital jerk nystagmus have 20/20 VA?

A

it depends on development, foveal hypoplasia, abnormal visual experience, etc

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22
Q

What is the treatment for congenital jerk nystagmus?

A

yoked of BO prims, surgery, VT, biofeedback, contact lenses

23
Q

What are two types of congenital jerk nystagmus?

A

latent and manifest latent

24
Q

T/F traditional latent is not seen binocularly

A

true

25
Q

What are two types of manifest latent nystagmus?

A

pendular or jerk with both eyes open

26
Q

T/F latent jerk nystagmus gets better monocularly

A

false, worse with one eye covered

27
Q

Describe the movement of latent jerk nystagmus with one eye occluded

A

drifts toward occluded eye with refixation toward viewing eye, slow phase then fast phase

28
Q

How do you label a monocular latent jerk nystagmus?

A

label by the fast phase (toward the open eye)

29
Q

What is a gaze-evoked jerk nystagmus?

A

gaze-holding, velocity decreases during slow phase

30
Q

What conditions cause gaze-evoked jerk nystagmus?

A

drug use, cerebellar disorder, vestibular disorder, multiple sclerosis

31
Q

T/F endpoint nystagmus is normal

A

true

32
Q

Why is endpoint nystagmus evoked?

A

from attempted maintenance of extreme eye position

33
Q

What is the most common form of nystagmus?

A

gaze-evoked

34
Q

Describe the motion of gaze-evoked nystagmus

A

slow phase away from eccentric position (trying to hold eccentric gaze) then fast phase snaps back out

35
Q

T/F gaze evoked nystagmus is due to a deficient eye position signal in the neural integrator network

A

true

36
Q

How can end point nystagmus and gaze-evoked nystagmus be differentiated?

A

endpoint has lower intensity and is not associated with other ocular motor abnormalities

37
Q

What is vestibular jerk nystagmus?

A

central or peripheral, constant velocity slow phase, made worse by head position change

38
Q

What direction is central vestibular jerk nystagmus?

A

usually vertical

39
Q

What direction is peripheral vestibular jerk nystagmus?

A

usually horizontal

40
Q

How does fixation effect vestibular jerk nystagmus?

A

suppresses peripheral but does not suppress central

41
Q

What is spasmus nutans?

A

rare condition w/ triad of nystagmus, head nodding and torticollis, onset 3-15 months and disappearance by 3-4 years

42
Q

Describe spasmus nutans

A

small amplitude, high frequency oscillations, usually bilateral but can be monocular, asymmetric and horizontal and variable in different positions of gaze

43
Q

What is periodic alternating nystagmus?

A

conjugate, horizontal jerk nystagmus with fast phase in one direction for 1-2 minutes, intervening neutral phase for 10-20 sec and then opposite direction beating 1-2 minutes, repeat

44
Q

What is the mechanisms of periodic alternating nystagmus?

A

disruption of vestibulo-ocular tracts at the pontomedullary junction

45
Q

What is INO (abducting nystagmus of internuclear ophthalmoplegia?

A

nystagmus in the abducting eye contralateral to a medial longitudinal fasciculus lesion

46
Q

What must spasmus nutans be differentiated from?

A

congenital nystagmus and intracranial tumors which also result in head nodding and nystagmus

47
Q

What are the two types of caloric testing and what direction is the eye movement?

A

warm water: slow away fast back; cold water: slow toward, fast away

48
Q

What is COWS in caloric testing?

A

cold opposite warm same (describing the direction of the fast movements)

49
Q

When does foveation occur during pendular nystagmus?

A

when velocity is the slowest (when pendulum movement reverses direction)

50
Q

When does foveation occur during jerk nystagmus?

A

immediately after the saccade or fast portion

51
Q

Why is prism used to treat nystagmus?

A

can identify null point and use prism to move target , will dampen nystagmus

52
Q

Which VA was better with prism treatment?

A

distance better than near

53
Q

T/F you cannot use auditory feedback with nystagmus

A

false

Ocular Motility (13 decks)

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