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Ocular disease 3 > Nystagmus_Dr. M. Sharma > Flashcards

Nystagmus_Dr. M. Sharma Flashcards

1
Q

Where is the probable location of a upbeat nystagmus?

A

Posterior fossa (medulla most common)

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2
Q

Where is the probable location of a periodic alternating nystagmus?

A

Cerebellar nodulus

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3
Q

Where is the probable location of a ocular bobbing?

A

Pontine destructive lesion

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4
Q

Where is the probable location of a ocular flutter/opsoclonus?

A

Pons (pause cells); cerebellum (connections to pons)

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5
Q

Where is the probable location of a convergence-retraction nystagmus?

A

Pretectum (dorsal midbrain)

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6
Q

Where is the probable location of a see-saw nystagmus?

A

Paraellar/diencephalon

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7
Q

Where is the probable location of a monocular nystagmus of childhood?

A

optic nerve/chiasm/hypothalamus

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8
Q

central vestublar nystagmus is a mixed __________ trajectory?

A

horizontal-torsional

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9
Q

Central vestibular nystagmus usually beats away or towards the side of the vestibular lesion?

A

away

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10
Q

Does central vestibular nystagmus associates with neurologic signs and symptoms?

A

Yes

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11
Q

How is the VA of the people who has central vestibular nystagmus?

A

VA may be normal small amplitude outside primary position

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12
Q

Which nystagmus is the most common form of central vestibular nystagmus?

A

downbeat nystagmus

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13
Q

What is a downbeat nystagmus look like?

A

results from lesions that produce defective vertical gaze holding characterized by an upward drift of the eyes, which is then corrected with a downward saccade.

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14
Q

Does downbeat nystagmus follow the ALEXANDER’S LAW?

A

Yes

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15
Q

In what position does the downbeat nystagmus usually accentuated?

A

downgaze, especially to either side.

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16
Q

T/F In downbeat nystagmus, the lesion is in vestibulocerebellum and diminish the tonic output from the anterior semicircular canals to the ocular motoneurons.

A

True

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17
Q

What is the most common structural lesion of a downbeat nystagmus?

A

Arnold-Chiari Type 1 malformation. Lesion of the foramen magnum

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18
Q

What are the treatments for downbeat nystagmus?

A
  1. Common treatments are “off label” include Clonazepam, Baclofen and Gabapentin
  2. Base-Out prisms (induce convergence)
  3. Memantine, 4-Aminopyridine and 3,4-Diaminopyridine
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19
Q

where is the probable location of lesion with downbeat nystagmus?

A

Cervical-medullary junction

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20
Q

upbeat nystagmus is caused y lesions in the posterior fossa of which part?

A

Brainstem (often medulla) and The anterior cerebellar vermis

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21
Q

The most common causes of upbeat nystagmus are _______, _______, ________, and ________.

A

Demyelination
Stroke
Cerebellar degeneration
Tobacco smoking

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22
Q

Purely torsional nystagmus indicates a _______ lesion.

A

central lesion, associates with a medullary lesion (eg. syingobulbia, lateral medullary infarction)

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23
Q

Periodic alternating nystagmus oscillates predictably in ________, ______ and ______.

A

direction, amplitude and frequency

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24
Q

Is periodic alternating nystagmus congenital or acquired?

A

can be both

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25
Q

Periodic alternating nystagmus is typically associated with dysfunction of the _______ and _______.

A

cerebellar nodulus and uvula

26
Q

What is the drug of choice to effectively treat acquired form of nystagmus?

A

Baclofen

27
Q

Acquired pendular nystagmus with both vertical and horizontal components produces ________ (if the components are in phase) or ________ or ________ nystagmus (if the components are out of phase).

A

oblique, circular, elliptical

28
Q

The eye movements in acquired pendular nystagmus may be conjugate or disconjugate and are often _________.

A

dissociated

29
Q

Oculopalatal myoclonus or tremor is an acquired _________ plus ________.

A

pendular nystagmus, myoclonus

30
Q

Oculopalatal myocolonus usually arises several months after a lesion occus that involves the _________.

A

Guillain-mollaret triangle

31
Q

Which kind of nystagmus produces an inferior olivary hypertrophy?

A

Oculopalatal myoclonus. When the lesion is within central tegmental tract, it can disrupt transmission between the cerebellum, specifically the flocculus,, and the inferior olive.

32
Q

See-saw nystagmus is a form of disconjugate nystagmus in which 1 eye _____ and _____ while the other eye ______ and ______.

A

elevates, intorts

depresses, extorts

33
Q

See-Saw nystagmus is most commonly observed in patients with large tumors of the parasellar region that impinge on the ______ ventricle.

A

third
Craniopha-Ryngioma is a frequent cause
Other parasellar-diencephalic tumors and trauma may als produce see-saw nystagmus

34
Q

See-Saw nystagmus may be associated with vision loss and often looks like ________ hemianopia.

A

bitemporal

35
Q

In dissociated nystagmus, the most common form of this disorder is one that is associated with lesions of the __________, which produce an internuclear ___________.

A

medial longitudinal fasciculus (MLF)

Ophthalmoplegia (paralysis of the muscles within or surrounding the eye)

36
Q

How does dissociated nystagmus look like?

A

isolated slowing of adduction of the eye isilateral to an MLF lesion, which create excessive saccadic movements in the contralateral rectus muscle (abduction). That’s according to Hering’s Law.

37
Q

What are the Gaze-holding deficiency nystagmus (neural integrator)?

A
  1. eccentric gaze nystagmus ( and associated rebound nystagmus)
  2. Gaze instability (“Run-away”) nystagmus.
38
Q

What is eccentric gaze nystagmus?

A

It develops becaue of an inability to maintain fixation in eccentric gaze. Eyes drift back to the midline and a corrective saccades reposition the eyes on the eccentric target with a fast phase.

39
Q

What law is Eccentric gaze nystagmus follows?

A

Alexander’s law. Nystagmus increases in intensity (amplitude and frequency) as the eyes are moved in the direction of the fast phase.

40
Q

Eccentric gaze nystagmus is caused by dysfunction of the ________ integrator.

A

neural

  • For horizonal gaze, the neural integrator include the nucleus prepositus hypoglossi and the medial vestibular nuclei
  • For vertical gaze the interstitial nucleus of Cajal serves as the neural integrator
  • The flocculus and nodulus of the cerebellum also play a role in maintaining an eccentric position of gaze.
41
Q

Rebound nystagmus is often a manifestation of _________ disease.

A

cerebellar

42
Q

what is gaze instability (run-away) nystagmus look like?

A

ocillation slow phases are directed away from central position

43
Q

Gaze instability (run-away) nystagmus is associated with ________ signs and symptoms.

A

neurologic

44
Q

In gaze instability nystagmus, ocular motility recording show slow phase that are accelerating or decelerating?

A

accelerating

45
Q

What is the treatment for superior oblique myokymia?

A

Carbamazepine

46
Q

What are the treatment for downbeat and other central vestibular forms of nystagmus?

A

occasionally be helped by clonazepam, A GABA agonists

47
Q

What would you use that may improve visual acuity in patients with congenital nystagmus?

A

contact lenses

48
Q

What are the non-medical treatments for nystagmus?

A
  1. Prisms such as base out prisms to induce convergence if nystagmus diminishes with convergence
  2. contact lenses to improve VA in patients with congenital nystagmus
49
Q

What are the other eye movement disorders?.

A
  1. voluntary flutter (“nystagmus”)
  2. convergence-retraction nystagmus
  3. superior oblique myokymia
  4. oculomasticatory myorhythmia
  5. ocular bobbing
50
Q

What is the motion you see with voluntary flutter (“nystagmus”)?

A

rapidly oscillating eye movement (almost always horizontal) that can be induced volitionally.
The movement lack slow phases, so it’s not a form of nystagmus.

51
Q

Voluntary flutter appear as high-frequency, conjugate, back to back saccades without an ___________.

A

intersaccadic interval

52
Q

Voluntary flutter is associated with convergence and often with eyelid flutter and ________.

A

facial grimacing

53
Q

is Convergence-retraction nystagmus a true nystagmus?

A

no because it doesn’t have a slow phase

54
Q

Convergence-retraction nystagmus is often associated with paresis of what gaze?

A

upgaze

55
Q

What is the Collier sign and which nystagmus has this?

A

Near dissociation, skew deviation and bilateral eyelid retraction

56
Q

Superior Oblique Myokymia produces ________, _______, ________ bursts of contraction of the superior oblique muscle.

A

paroxysmal, monocular, high frequency

57
Q

Does Superior Oblique Myokymia shows large or small amplitude?

A

small amplitude and magnification is usually required.

58
Q

Is Superior Oblique Myokymia malignant or benign?

A

It is almost always benign, although there are rare reports of its association with MS and posterior fossa tumor

59
Q

What is oculomasticator myorhythmia?

A

It develops pendular, vergence oscillations that occur with contractions of the masticatory muscles.

60
Q

What is an early neurologic finding in whipple disease?

A

vertical saccadic palsy

61
Q

What is the eye movements you see with ocular bobbing?

A

rapid downward movement of both eyes, followed by a slow return of the eyes to the midline position.

62
Q

Where is the lesion that causes ocular bobbing?

A

Usually in the pons, secondary to infarction or hemorrhage.

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