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TAS Opthalmology > Nystagmus ✅ > Flashcards

Nystagmus ✅ Flashcards

1
Q

What is nystagmus?

A

Rhythmic oscillation of the eyes

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2
Q

In what terms can nystagmus be described?

A
  • Type
  • Direction
  • Plane
  • Amplitude
  • Rate
  • Conjugacy
  • Null zone
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3
Q

What are the types of nystagmus? -

A
  • Pendular

- Jerk

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4
Q

What is meant by pendular nystagmus?

A

Phases of equal velocity

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5
Q

What is meant by jerk nystagmus?

A

Phases of unequal velocity

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6
Q

What is described in the ‘direction’ of nystagmus?

A

The direction of the fast component

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7
Q

What are the ‘planes’ of nystagmus?

A
  • Horizontal
  • Vertical
  • Rotatory
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8
Q

What are the ‘amplitudes’ of nystagmus?

A
  • Coarse
  • Medium
  • Fine
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9
Q

What are the ‘rates’ of nystagmus?

A
  • Slow

- Fast

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10
Q

What is meant by conjugacy in nystagmus?

A

Both eyes demonstrate the same movement

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11
Q

What is meant by null zone in nystagmus?

A

A point of gaze in which the nystagmus intensity is minimal

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12
Q

What are the types of physiological nystagmus?

A
  • Optokinetic
  • Rotational
  • Caloric
  • End-point
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13
Q

Where is end-point nystagmus seen?

A

Extremes of gaze, or after sustained deviation of the eyes

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14
Q

When is gaze-evoked nystagmus often seen?

A

As a consequence of therapeutic doses of anti-convulsants

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15
Q

What are the major categories of causes of pathological nystagmus?

A
  • Infantile sensory nystagmus
  • Infantile idiopathic motor nystagmus
  • Acquired nystagmus secondary to neurological disease
  • Acquired vestibular nystagmus
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16
Q

What causes infantile sensory nystagmus?

A

Poor vision or afferent sensory problems, e.g. aniridia, albinism

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17
Q

What is the most common cause of pathological nystagmus?

A

Infantile idiopathic motor nystagmus

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18
Q

What is infantile idiopathic motor nystagmus associated with?

A

Otherwise normal ocular and neurological function

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19
Q

When is infantile nystagmus noticed?

A

In the first few months of life

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20
Q

What are the characteristic features of infantile nystagmus?

A
  • Usually horizontal (can be vertical or rotatory) and uniplanar
  • Usually jerk (but may be pendular)
  • Conjugate and similar in amplitude in both eyes
  • May have associated head oscillation
  • Null point of gaze where nystagmus is less marked
  • Usually dampened by convergence
  • Worsens when one eye covered
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21
Q

What is meant by uniplanar nystagmus?

A

Does not change plane in different positions of gaze

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22
Q

What is the result of infantile nystagmus having a null point of gaze?

A

The child will often adopt a head position to put their eyes in that position of gaze

23
Q

What is the result of infantile nystagmus being dampened by convergence?

A

Near vision is better than distance vision

24
Q

Why do infants with nystagmus need to be seen by an ophthalmologist?

A

To exclude a causative ocular abnormality

25
Q

When can idiopathic motor nystagmus (IMN) be diagnosed?

A

If child’s visual development, eye examination, visual electrodiagnostics, and general development are normal

26
Q

What might X-linked IMN result from?

A

Gene mutations from FRMD7

27
Q

What kind of nystagmus should trigger concern about potential neurological disease?

A

Disconjugate nystagmus

28
Q

What is the importance of the pattern of nystagmus in acquired nystagmus due to neurological disease?

A

It can help localise the pathology

29
Q

What are the patterns of nystagmus seen by acquired nystagmus due to neurological disease?

A
  • See-saw nystagmus
  • Upbeat nystagmus
  • Downbeat nystagmus
  • Periodic alternating nystagmus
  • Spasmus nutans
  • Convergence-retraction nystagmus
  • Opsoclonus
  • Ocular bobbing
  • Cerebellar system disease
30
Q

What is see-saw nystagmus?

A

Pendular - one eye elevates and rotates inwards, while the other eye depresses and rotates outwards

31
Q

What causes see-saw nystagmus?

A

Supra-sellar and rostral midbrain lesions

32
Q

What is upbeat nystagmus?

A

Jerk, vertical with fast phase downwards

33
Q

What causes upbeat nystagmus?

A

Lesions of cerebellar vermis and brainstem

34
Q

What is downbeat nystagmus?

A

Jerk, vertical with fast phase downwards

35
Q

What causes downbeat nystagmus?

A

Lesions of the cervico-medullary junction at the level of the foramen magnum, e.g. Arnold-Chiari malformation

36
Q

What is periodic alternating nystagmus?

A

Jerk, horizontal with fast phase alternating from one side to the other after a short rest period

37
Q

What causes periodic alternating nystagmus?

A
  • Arnold-Chiari malformation
  • Spinocerebellar degeneration
  • Trauma
  • Posterior fossa tumours
38
Q

What is spastic nystagmus?

A

Triad of head turn, head nodding, and nystagmus

39
Q

At what age does spasmus nutans occur?

A

Starts within first 18 months, and resolves by 3 years

40
Q

Is spasmus nutans benign?

A

Yes

41
Q

What are the features of the nystagmus in spasmus nutans?

A

Can be horizontal, vertical, pendular, or dysconjugate

42
Q

What can the features of spasmus nutans be mimicked by?

A

Chiasmal, suprachiasmal, or third ventricle tumours

43
Q

What is convergence-retraction nystagmus?

A

Jerk convergence-eye retraction movements on attempts of upgaze

44
Q

What is convergence-retraction nystagmus usually associated with?

A

Defective upgaze and light-near dissociation as part of dorsal midbrain syndrome

45
Q

What is opsoclonus?

A

Bursts of rapid, multivectorial, chaotic and conjugate eye movement abnormality

46
Q

What might opsoclonus be associated with?

A

Myoclonus

47
Q

What can cause opsoclonus?

A
  • Infectious encephalopathy

- Non-metastatic feature of occult neural crest tumours, e.g. neuroblastoma

48
Q

What is ocular bobbing?

A

Fast conjugate vertical movements with fast phase downwards

49
Q

When might ocular bobbing be seen?

A
  • Metabolic encephalopathy

- Obstructive hydrocephalus

50
Q

What constitutes cerebellar system disease?

A
  • Gaze-evoked nystagmus
  • Ocular dysmetria
  • Visual fixation instability
51
Q

What is acquired vestibular nystagmus usually associated with?

A

Other symptoms such as deafness, tinnitus, and vertigo

52
Q

What kind of nystagmus is produced by vestibular disease?

A

Horizontal-rotatory primary position uni-directional jerk nystagmus

53
Q

In what direction is the fast beat stage in nystagmus caused by vestibular disease?

A

It beats away from the diseased vestibular system

TAS Opthalmology (9 decks)

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