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Binocular Vision > Supranuclear Disorders - Miriam > Flashcards

Supranuclear Disorders - Miriam Flashcards

1
Q

what is the higher centre responsible for?

A

calculates type of movement and degree of movement required

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2
Q

what are the 6 areas that are part of the higher centre control areas?

A

Primary visual cortex (PVC)
Frontal eye fields (FEF)
Parieto occipital cortex (POC)
Supplementary eye fields (SEF)
Cerebellum
Superior colliculus (SC)

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3
Q

what do the blue and red lines indicate in the image?

A

saccades= red
smooth pursuit=blue

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4
Q

what are brainstem generator nuclei responsible for?

A

delivering activity to the ocular motor neurones (III,IV,VI)- controlling which muscles in eye will ‘fire’

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5
Q

which one of the brainstem generator nuclei are responsible for H saccades?

A

Para pontine reticular formation (PPRF)

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6
Q

what is the Rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) responsible for?

A

-V saccades
-Bilateral control

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7
Q

what is the Mesencephalic Reticular Formation (MRF) responsible for?

A

vergence

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8
Q

what is the Medial vestibular nucleus responsible for?

A

Vestibular Ocular Reflex
Smooth Pursuit

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9
Q

3 categories of Brainstem oculomotor anomalies?

A
  1. Supranuclear Above 3 nuclei so defect to one of the higher centres or one of brainstem generators.
  2. Internuclear : mlf defect- runs through all 3 nuclei.
  3. Infranuclear : Below 3 nuclei - these are actual nerves (nerve palsies).
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10
Q

what is the internuclear part of the brainstem also referred to?

A

MLF

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11
Q

List the 5 types of eye movements

A
  1. Saccades
  2. Smooth pursuit
  3. Vergence
  4. Vestibular ocular
  5. Optokinetic
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12
Q

How does a voluntary saccade occur?

A

via the frontal eye field

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13
Q

How does a reflexive Saccade occur?

A

via the parietal eye field

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14
Q

What are the steps of a normal horizontal saccadic movement to move to the left?

A
  1. Right FEF (voluntary saccade) or Right PEF (reflexive saccade)
  2. Left PPRF stimulates left abducens nucleus (VI)
  3. Abducens nucleus contains abducens motor neurones which innervate left LR
  4. Abducens nucleus also contains abducens internuclear neurones with axons that project via MLF to innervate the contralateral oculomotor nucleus
  5. Oculomotor nucleus contains motor neurones which innervate right medial rectus. due to herrings law
    Patient look to the left
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15
Q

In a normal H saccadic movement, why would a left oculormotor nucleus contain motor neurones which innervate the right MR and cause it to contract?

A

Due to Herrings Law

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16
Q

who first described Congenital Ocular Motor Apraxia
Saccadic Initiation Failure (SIF)?

A

Cogan

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17
Q

how quickly do parents notice problems in Congenital Ocular Motor Apraxia Saccadic Initiation Failure (SIF)? what do parents notice?

A

Problems noticed from a few months old:
1. History: parents note an apparent lack of attention & question vision problem
2. Maybe associated with delayed walking/talking or other neurological problems- milestone problems

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18
Q

what eye movements are affected in Congenital Ocular Motor Apraxia
Saccadic Initiation Failure (SIF)? and what stays normal?

A
  1. Affects horizontal voluntary gaze (saccades)
    (Vertical gaze usually normal)
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19
Q

What is Acquired ocular motor apraxia?

A
  1. Inability to do voluntary saccades- have some ability to do reflexive saccades
  2. Difficulty making horizontal & vertical saccades to command
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20
Q

Are V saccades usually affected in congenital or acquired motor apraxia?

A

Acquired

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21
Q

Are H saccades usually affected in congenital or acquired motor apraxia?

A

Congenital and Aquired

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22
Q

what are associated diseases to Aquired oculor motor apraxia?

A
  1. Huntington’s disease
  2. Multiple sclerosis
  3. Wilson’s disease (build up of copper in the body)
  4. Iatrogenic (aortic surgery)
  5. Damage possibly occurs in the frontal eye field parietal cortex
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23
Q

what are some characteristics of congenital OM apraxia?

A

1.Head thrusts- to change fixation (VOR)
2.Eye movement follows head movement until target fixated
3.Head then moves slowly back to mid line
4.Repetitive blinking - to BREAK fixation

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24
Q

why would a child use head thrusts in congenital OM apraxia?

A

to CHANGE fixation. If the head moves to the left the eyes will move to the right

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25
Q

why would a child use BLINKS in congenital OM apraxia?

A

to BREAK fixation

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26
Q

Do head thrusts increase or decrease as the child gets older? why?

A

Decrease- child develops better coping mechanisms

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27
Q

What is smooth pursuit palsy?

A

1.Loss of smooth pursuit (very rare)

  1. Using series small amplitude saccades (cog-wheel). Looks jerky
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28
Q

What causes a smooth pursuit palsy?

A

Aneurysm or tumour at the parietal-occipital lobe.

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29
Q

What is vergence system failure?

A
  1. Convergence paralysis
  2. Divergence paralysis
  3. Spasm of the near reflex
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30
Q

Is spasm of the near reflex to do with convergence or accommodation?

A

Both

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31
Q

What occurs/happens in convergence paralysis

A
  1. Fine in distance
  2. Head trauma
  3. XOT > near
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32
Q

What occurs/ happens in divergence paralysis?

A

Stroke or head trauma
SOT > distance

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33
Q

Why exotropia in convergence and esotropia in divergence paralysis?

A

Convergence: the eyes should be moving in. The eyes move out instead = exo
Divergece : the eyes should be moving out. The eyes move in instead = Eso

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34
Q

what occurs/happens in spasm of the near reflex?

A
  1. Pupil miosis
  2. Accommodative spasm
  3. Convergence
  4. This is psychogenic in nature
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35
Q

Does the optokinetic system use saccades or smooth pursuits?

A

Both
intact pursuit system (slow phase)
Intact saccadic system (fast phase)

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36
Q

What does failure of the vesitbular system result in?

A

Skew deviation

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37
Q

what are skew deviations associated with?

A
  1. Usually associated with brainstem or cerebellar disease
  2. Deviation improves supine (Agnes Wong test) if > 50% then most likely skew deviation
  3. Vertical strabismus. There is Incyclotosion f higher eye
38
Q

WHat is the Agnes Wong test?

A

This is whent he px lies flat on the ground. If the skew devation improves by around 50% then it is most likely a skew devation.

39
Q

What is a skew devation?

A

This is normally a hyperdevation where the higher eye has incyclotorsion. : related to cerebellar disease / brainstem. (refer ASAP)

40
Q

Aetiology of unilateral gaze palsy?

A
  1. Lesion usually in the pons at the level of the VI nerve nucleus- right next to pprf as well
  2. Demyelinating disease(ms)
  3. Vascular(aneurysm)
  4. Tumour
41
Q

What happens to eye movements in unilateral gaze palsy?
(example in lecture)

A
  1. Damage to VI nerve nucleus & or PPRF
  2. Deviation of eyes to the opposite side
  3. Not able to move eyes to ipsilateral side.
    Able to move eyes to contralateral side
42
Q

what happens in mild unilateral gaze palsy?

A

Only affects PPRF :
slow ipsilateral saccades with sparing of pursuit & VOR

43
Q

WHat actually happens in mild unilateral gaze palsy if the px moves their head to the right hand side (VOR)?

A
  1. Horizontal canal is stimulated by H head movement
  2. This will send a signal to the right medial vestibular nucleus.
  3. The medial vestibular nucleus will send a signal to the left 6th nerve nucleus
  4. The left lateral rectus will contract and the right medial rectus will also contract.

This shows that VOR is preserved.
But no saccades as the PPRF is broken

44
Q

what happens in severe unilateral gaze palsy?

A

1.Complete palsy of ipsilateral horizontal gaze (both pursuit & saccadic)
2.Large lesions affect 6th nerve and vestibular nuclei - so VOR also affected usually associated with gaze evoked nystagmus

45
Q

What controls vertical movements?

A

Bilateral upper centre control (riMLF)

46
Q

Why don’t Isolated cerebral hemisphere lesions not lead to vertical gaze palsies?

A

As other rimlf still works and can BIL movements ; you need both riMLF to be damaged in order to have a verticle palsy.

47
Q

Do isolated supranuclear preserve VOR Bell’s phenomenon & caloric nystagmus

A

yes

48
Q

Do large lesions also affect ocular motor nuclei?

A

yes so also lose VOR

49
Q

Another name for Dorsal Midbrain Syndrome?

A

Parinauds syndrome

50
Q

What is the aetriology of dorsal midbrain syndorme(parinauds)?

A
  1. Normally pineal tumour
  2. Vascular accident
  3. Trauma
51
Q

What are the features of parinauds?

A
  1. Initial loss of upward saccades despite normal smooth pursuit
    we rotate OKN drum both ways as
  2. OKN drum rotated downwards absence re-fixation (no upward saccade)
  3. Upward drum rotation normal response (upward pursuit maintained)
52
Q

What will a upwards VOR findings be for the initial stage of dorsal midbrain syndrome

A
  1. smooth pursuits for Upwards is preserved
  2. The downward saccades is preserved.

So the movmeent will look normal.

53
Q

What happens to the eyes when the drum is rolled downward? in dorsal midbrain syndrome

A

1.The eyes will smoothly move down okay
2.But when going up their is an issue due to the upward saccades being lost
This casues:
- Eyes move back in on themselves in this condition- conv retraction nystamus

54
Q

how does a progressive lesion present in parinauds?

A

Loss of upward saccades followed by:
Loss of upward smooth pursuit
Loss of saccadic and smooth pursuit down gaze-slowly

55
Q

what else can present alongside parinauds?

A
  1. Conv retraction nystagmus
  2. Upper eyelid retraction (colliers sign)
  3. Pupils dilated : light - near dissociation
  4. Sometimes papillodeoma
56
Q

what happens in conv retraction nystagmus?

A

eyes converge & retract on attempted up gaze

57
Q

what is another word for upper eyelid retraction?

A

colliers sign

58
Q

what will we see with the dilated pupils?

A

(demonstrate light near dissociation)- so wont react to light but will to near target (accom + conv)

59
Q

why would we potentially see pap in a parinauds px?

A

common aetiology is pineal tumour so pressure gonna go up

60
Q

What is the aetiology of Progressive supranuclear palsy
(Steele –Richardson syndrome)?

A

Degeneration of the brainstem reticular formation

61
Q

feautuures of Degeneration of the brainstem reticular formation
(think of as opposite to parinauds)?

A
  1. Initially slowing of the vertical saccadic velocity
  2. First down gaze then complete vertical saccadic paralysis
  3. Horizontal gaze problems late feature
  4. Difficulty opening lids
62
Q

What are systemic neurological features of supranuclear palsy?

A
  1. Axial rigidity (body becomes rigid?)
  2. Problems with :Speech, Swallowing, Balance, Seeing food on plate, Walking downstairs
  3. Progressive dementia
  4. Mortality after 10 years
63
Q

What are the features of Parkinson’s disease?

A
  1. Impaired up gaze ; Their downgaze is usally normal.
  2. Convergence insufficiency
64
Q

What type of disorder causes the MLF to be disrupted?

A

Internuclear disorders

65
Q

3 types of internuclear disorders?

A
  1. Internuclear ophthalmoplegia (INO)
  2. One and a half syndrome
  3. Bilateral INO
66
Q

In internuclear Ophthalmologia, what palsy happens as a result to lesion in MLF?- EG IN LECTURE

A
  1. The PPRF will send signal to the 6th nerve nucleus
  2. The nucleus will innervate the lateral rectus and try to send a signal to the 3rd nerve
  3. But there is a lesion in the MLF ; inter neurons
  4. This means the other side will not adduct. ; Exotropia
67
Q

In unilateral INO, what eye movements are affected with loss of adduction?

A

Loss aDduction affects:
saccades
smooth pursuit
VOR
OKN

68
Q

will milder forms of loss of adduction in unilateral INO affect all eye movements?

A

no, may just cause loss of peak saccadic velocity

69
Q

Why is nystagmus induced with the loss of aDduction?

A

The contralateral eyes lateral will keep trying, as the muscles are still yoked together. This causes abducting nystagmus.

70
Q

if lesion is discrete in ION is convergence retained?

A

yes

71
Q

if lesion is in upper part of MLF is convergence retained?

A

nope

72
Q

How do you know if a lesion if big or small in internuclear opthalmoplegia?

A

See if convergence is present.

73
Q

In Bilateral Internuclear Ophthalmoplegia (ION) why are both nerves affected?

A

Lesions large enough to affect interneurons running in the MLF from both 6th nerves. Therefore both 3rd nerve nuclei will not receive input.

74
Q

What loss of eye movement happens in Bilateral Internuclear Ophthalmoplegia?

A

Bilateral loss of adduction:
1.VOR
2.OKN
3.saccades
4.smooth pursuit
5. Abducting nystagmus

75
Q

Why would someone have abducting nystagmus with bilateral internuclear ophthalmoplegia ?

A

Because the lateral rectus are both working
-also as MLF is disrupted = loss of ADDUCTION so ABDUCTION present only

76
Q

Can convergence be retained in BIL INO?

A

Yes if the lesion is discrete

77
Q

Is BIL INO asymmetric?

A

Often asymmetric (exo more asymmetric side)

78
Q

what is one and a half syndrome?

A

Extensive caudal lesion affects:
1. Horizontal gaze centre (PPRF) AND adjacent MLF.

This is a two in one, hitting two parts. Its called one and a half syndrome but it should be called one big danger.

79
Q

What does one and a half syndrome cause?

A
  1. Loss of aBduction one side
  2. Loss of aDduction Both side
  3. Abducting nystagmus unaffected LR
80
Q

Why is there a loss of abduction ,in one eye,in one and a half syndrome?

A

Because there is a lesion in the PPRF!
1. Signal does not send to the 6th nerve nucleus
2. The lateral rectus is not innervated

81
Q

Why is there a loss of adduction, in both eyes, in one and a half syndrome?

A

Lesion to the PPRF and Lesion to the MLF. This is a mouthful but read slow and use the diagram:

PPRF lesion:
1. PPRF does not innervate the 6th nerve.
2. 6th nucleus is not innervated.
3. This means the nucleus will not send anything to the 3rd nucleus to hit the medial rectus!

Contralateral MLF lesion:
1. PPRF on the opposite side works, if you do not understand why this works, look at the diagram or watch the lecture at 40:47.
2. PPRF works, so it will innervate the 6th nucleus and the lateral rectus as normal.
3. But now the nucleus is trying to send signals to the 3rd nerve nucleus on the other side again. But there is no signal going there due to lesion.
4. No innervation to the 3rd nucleus and no contraction to the medial rectus.

82
Q

So what is One and a half syndrome classified as?

A

Split into two parts:
1. Unilateral gaze palsy (PPRF lesion)
2. Internuclear Opthalmoplegia (MLF lesion)

83
Q

Why do you get abducting nystagmus of the unaffected LR?

A

Muscles are yolked. It will keep trying even though the medial rectus is not working, so this caused a nystagmus

84
Q

what can be used in one and a half syndrome to achieve central fixation?

A

CHP

85
Q

What tests can we do to diagnose INO?

A
  1. Cover test= Usually exophoria or exotropia affected eye
  2. Saccades are affected to a greater extent than pursuit- esp horizontal
  3. OKN impaired
  4. Hess provides a record of progress
  5. ABducting nystagmus contralateral eye
86
Q

systemic investigations when diagnosing INO?

A
  1. Full medical history
  2. Full medical assessment: Blood tests, Blood pressure, EKG, MRI/CT,
  3. Assessment of 12 cranial nerves
87
Q

what work-up can be done for neurological cases?

A

BV workup:
Visual acuity
Fundus examination
IOP
Visual field
Pupils examination
Colour vision
Cover test
Ocular movements (smooth pursuit)
Measurement of the deviation
BV assessment (fusional reserves-stereo acuity)
Demonstrate Bell’s intact
Investigate nystagmus

88
Q

If you suspect a neurological defect, other then OM what else would you want to test?

A

Convergence
OKN
VOR
Saccades
Electro diagnostics of all of the above

89
Q

what do we do when we notice :
Eye movements systems not working in one position of gaze
Pupil changes
Lid position changes
Other neurological problems
Eye deviation in one position
Strabismus
problems with speech, sense etc

A

REFER
could be more sinister pathologies not covered in lecture

90
Q

typical management strategies of supranuclear internuclear disorders?

A

Immediate referral into the HES
Often combine with inter/infra/nuclear

Determine aetiology

Use CHP to avoid diplopia & oscillopsia

Prisms/ Occlusion to avoid diplopia

Cosmetic surgery possible (need to ensure does
not worsen symptoms)

Binocular Vision (30 decks)

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