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Binocular vision YR 3 > supra nuclear/intra nuclear palsies > Flashcards

supra nuclear/intra nuclear palsies Flashcards

1
Q

what does the infra nuclear system connect

A

the nuclear of the neuron to the muscle

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2
Q

where is the supra nuclear and inter nuclear systems located and what do they control

A
  • further up into the brain

- they control the eye movements

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3
Q

where is the higher centre control
what does the higher centre do
list the 6 higher centre control areas starting from the front and going further back

A
  • it is above the level of the nucleus
  • Calculates the type of movement and the degree of movement required
    Co-ordinates the 2 eyes to get there at the same time
  • Primary visual cortex (PVC)
  • Frontal eye fields (FEF)
  • Parieto occipital cortex (POC)
  • Supplementary eye fields (SEF)
  • Cerebellum
  • Superior colliculus (SC)
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4
Q

what does the cerebellum do

A

it modulates the eye movements so the eyes move smoothly and stay where you want them to be

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5
Q

which part of the higher centre control area is responsible for vertical eye movements of both sides

A

Superior colliculus (SC)

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6
Q

which 6 higher centre control areas are responsible for saccades

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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7
Q

which 4 higher centre control areas are responsible for smooth pursuit

A
  • Primary visual cortex (PVC)
  • Frontal eye fields (FEF)
  • Parieto occipital cortex (POC)
  • Cerebellum
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8
Q

what are brainstem generator nuclei responsible for

A

for delivering bursts of activity to the ocular motor neurones (III,IV,VI)

which goes along the nerves and supplies to the eye muscles to produce eye movements

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9
Q

list the 3 brainstem generator nuclei and what type of eye movement each one is responsible for

A
  • Para pontine reticular formation (PPRF)
    Horizontal saccades
  • Rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF)
    Vertical Saccades
    Bilateral Control
  • Vestibular Nuclei
    Vestibulo-ocular Reflex
    Smooth Pursuit
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10
Q

what brainstem generator is responsible for horizontal saccades

A

Para pontine reticular formation (PPRF)

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11
Q

what brainstem generator is responsible for bilateral vertical saccades

A

Rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF)

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12
Q

what brainstem generator is responsible for the vestibular ocular reflex, smooth pursuit

A

Vestibular Nuclei

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13
Q

what is the aim of the ocular motor system

A

to maintain viewing through seven different types of eye movement

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14
Q

list the 5 types of gaze holding eye movements and the 2 types of gaze shifting eye movements

A 
Gaze holding
- Fixational
- Vestibular ocular 
- Optokinetic 
- -Smooth pursuit
 Vergence

Gaze Shifting

  • Saccades
  • Fast phase of nystagmus
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15
Q

what is the saccadic system used for
where is it generated
where is it mediated

A
  • Fast eye movements
  • To bring the object of interest onto the fovea
  • Generated in the contralateral frontal cortex
    and
  • Mediated in the brainstem

e.g. if want to look to the right very quickly, then need to use left side of frontal cortex

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16
Q

what is used to make voluntary saccades to the left

A

right frontal eye field

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17
Q

what is used to make a reflexive saccade to the left

A

right parietal eye field

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18
Q

list the stages of how a normal horizontal saccadic eye movement to the left is done

A
  • Right FEF (voluntary saccade) or Right PEF (reflexive saccade)
  • Left PPRF stimulates left abducens nucleus (VI)
  • Abducens nucleus contains abducens motor neurones which innervate left lateral rectus
  • Abducens nucleus also contains abducens internuclear neurones with axons that project via the contralateral medial longitudinal fasciculus (MLF) to innervate the contralateral oculomotor nucleus (III)
  • Oculomotor nucleus contains motor neurones which innervate right medial rectus

=
Patient look to the left

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19
Q

where will the damage be in a saccadic failure
what will this result in
what 2 things can cause this

A
  • Acute lesions in the frontal eye fields
  • Result in the eyes deviating towards the side of the lesion
  • Most common cause is CVA in the frontal region or slow growing tumours (which then won’t be sudden but developing)

e.g. if right frontal cortex governs movements towards the left, then if that fails, your eyes will deviate towards the right, because theres nothing to drive them leftwards

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20
Q

what did a saccadic initiation failure used to be called and what 2 types are there

A
  • ocular motor apraxia

- congenital or acquired

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21
Q

what happens in a congenital ocular motor apraxia (saccadic initiation failure)
when is it noticed
what do parents note
what is usually normal
what other things can it be associated with

A
  • congenital absence of saccades
  • noticed from a few months old if child is underdeveloped
  • parents note an apparent lack of attention and question vision problem say ‘baby can’t see’
  • vertical gaze usually normal
  • maybe associated with delayed walking/talking or other neurological problems
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22
Q

what happens in acquired ocular motor apraxia (saccadic initiation failure)
what is preserved
what is the px unable to do
which 2 diseases may it be seen in

A
  • Inability to execute voluntary saccades
  • Preservation of some reflexive saccades
  • Difficulty making both horizontal AND vertical saccades to command
  • May be seen in Huntingdon’s disease or MS
23
Q

list 4 things that characterise ocular motor apraxia (saccadic initiation failure) i.e. when cannot make saccadic eye movements

A
  • Head thrusts - To change fixation (where the VOR will drive the eyes over instead)
  • Eye movement follows head movement until target fixated
  • Head then moves slowly back to mid line
  • Repetitive blinking - To break fixation
24
Q

what does the smooth pursuit system:
generate and for what is particular
where is this control system located

A
  • Slow eye movements
  • To hold the image of a moving target
  • Control system is in the parieto-occipito-temporal junction
25
Q

what 2 things can cause a palsy of the smooth persuit system
what is the outcome of the eye movements as a result of the palsy

A
  • CVA or tumour - causing extensive parietal-occipital lobe damage may result in loss of smooth pursuit (very rare)
  • Track targets by using series small amplitude saccades (cog-wheel)
    e. g. when testing ocular motility, we are testing smooth pursuit system, and if the px hasn’t got smooth pursuit system as its affected by some inter cranial event = will see rapid cog wheeling saccades which are trying to keep up with the target
26
Q

what is the vergence system used for

A

To keep the images of an approaching or receding objects on both foveae

27
Q

what are the 3 types of vergence system failures that can happen
what is the cause of each one
what is seen in each one as a result

A
  • Convergence paralysis
    May be due to head trauma e.g. whiplash
    Divergent deviation increases on near fixation
  • Divergence paralysis
    May be due to stroke or head trauma
    Concomitant esotropia for distance
  • Spasm of the near reflex: convergence and accommodative spasm
    Cant see in distance and have a pseudo myopia and tiny pupils
    Often psychogenic
    Rarely due to disease
28
Q

what is the optokinetic system used for
what 2 things does it require to work
what can be used to test it

A
  • To steady the image on the retina when the visual world is moving
  • Requires both:
    intact pursuit system (slow phase)
    Intact saccadic system (fast phase)
    so can follow an object until it gets to the edge of movement and then be able to re-fixate again
  • Test with optokinetic drum
29
Q

what is the VOR system used for

A

To hold images steady during brief head movements and sustained head rotation

30
Q

what does a failure of the vestibular system result in
what sign will be seen in the patient and what tends to improve this
diseases of which 2 areas in the brain can cause this

A
  • Results in skew deviations
  • Transient or permanent vertical squints which are the same in all positions of gaze (concomitant), with incyclotorsion of the higher eye
  • Deviation will improve if the patient is supine i.e. lying down flat with their heads back (Agnes Wong test)
  • Usually associated with brainstem or cerebellar disease (as the cerebellar moderates the eye movements)
31
Q

what are horizontal and vertical gaze centres mediated through

A

specific gaze centres

32
Q

damage to which nerve and/or which brainstem generator will cause a unilateral gaze palsy
what symptoms will this px experience

A
  • Damage to VI (6th) nerve nucleus and/or PPRF
  • Deviation of eyes to the opposite side
  • Not able to move eyes to ipsilateral side (because haven’t got the drivers that drive the gaze over to where you want them to look)
  • Able to move eyes to contralateral side
33
Q

what is the aetiology of a unilateral gaze palsy

name 3 things that can cause this

A
  • Lesion usually in the pons at the level of the VI nerve nucleus
  • Demyelinating disease - MS
  • Vascular - stroke
  • Tumour - slow growing
34
Q

where is the control of vertical gaze movements

as a result of this, what type of lesions do not occur

A
  • Vertical movements under bilateral upper centre control (riMLF)
  • Therefore isolated cerebral lesions do not occur
    e. g. if its an isolated stroke that affects one side of the brain only = vertical movements are fine
35
Q

what 2 things does an isolated supra nuclear gaze palsy/lesion preserve
what do larger lesions affect and what happens as a result

A
  • Isolated supranuclear preserve VOR Bell’s phenomenon and caloric nystagmus
  • Large lesions (large enough to affect both sides of the brain e.g. a severe stroke) also affect ocular motor nuclei therefore also loose VOR
36
Q

what is the most common vertical gaze palsy condition known as

A

Dorsal midbrain syndrome (Parinaud’s syndrome)

37
Q

what are the 3 possible aetiologies of Dorsal midbrain syndrome (Parinaud’s syndrome)
what are the 3 symptoms
what are the 2 signs

A

Aetiology:

  • Normally pineal tumour
  • Vascular accident
  • Trauma
  • Progressive involvement in the dorsal midbrain usually due to tumours of the pineal gland

Symptoms:

  • Loss of up gaze
  • Convergence retraction nystagmus (as the eyes attempt to go up, you get convergence movements which are rapid, with the retraction of the whole globe)
  • Upper eyelid retraction (Colliers sign)

Signs:

  • Papilloedema (as they have something that affects the pressure inside the head)
  • Pupil abnormalities - light near dissociation (pupil will constrict if shine a light but won’t constrict if doing a near task = a mismatch between light affect and accommodative affect)
38
Q

list the 3 features of Dorsal midbrain syndrome (Parinaud’s syndrome)

A
  • Initially loss of upward saccades despite normal smooth pursuit
  • OKN drum rotated downwards absence re-fixation (no upward saccade)
  • Upward drum rotation normal response (upward pursuit maintained)

They have abnormal vertical OKN, they are able to make pursuit movement but not the refutation when they have to use the saccade movement

39
Q

which type of vertical gaze is affected in parkinson’s disease
what else is affected

A
  • Usually affects downgaze but may involve up gaze

- Poor/no convergence

40
Q

list 6 conditions that affect vertical movements

A
  • Dorsal midbrain syndrome (Parinaud’s syndrome)
  • Parkinson’s disease
  • Progressive supra-nuclear palsy (Steele-Richardson syndrome)
  • Tonic downwards lesions
  • Double elevator palsy (monocular elevation paresis)
  • Double depressor palsy (monocular depression paresis)
41
Q

with Progressive supra-nuclear palsy (Steele-Richardson syndrome):
what is it a degeneration of
what is impaired as a result of this
what is the prognosis of this condition

A
  • Degeneration of brainstem reticular formation
  • Impaired vertical saccades initially followed by paralysis and possibly full ophthalmoplegia (no eye movements at all)
  • Rapid progressive dementia and death within 10 years
42
Q

list the 4 features of Progressive supra-nuclear palsy (Steele-Richardson syndrome)

A
  • Initially slowing of the vertical saccadic velocity
  • First down gaze is affected, then complete vertical saccadic paralysis
  • Horizontal gaze problems late feature (can’t look for side to side)
  • Difficulty opening lids
43
Q

list all the systemic neurological features of Progressive supra-nuclear palsy (Steele-Richardson syndrome)

A
  • Axial rigidity
- Problems with: 
Speech
Swallowing
Balance
Seeing food on plate (poor downward eye movement)
Walking downstairs
  • Progressive dementia
  • Mortality after 10 years
44
Q

list 4 features of tonic downwards lesions and when is it seen

A
  • Chronic downward deviation
  • Failure of up gaze
  • Associated with children with hydrocephalus
  • Upper eye lid retraction (setting sun sign)
  • Seen when up gaze is lost
  • Eyes will be tonically downwards and can’t generate any upward movement
45
Q

what are the 4 features seen in Double elevator palsy (monocular elevation paresis)

A
  • Limitation up gaze in abduction and adduction
  • Saccades and smooth pursuit affected
  • Pseudo ptosis
  • VOR and Bells preserved

The elevation of one eye is affected and the px has a pseudo ptosis, because the eye is down theres nothing to support the lid so it looks as it they got a ptosis. and when get the px to rotate their eye up, the lid goes up too

46
Q

what is the feature of Double depressor palsy (monocular depression paresis)

A

Limitation down gaze abduction and adduction

47
Q

what happens in Inter nuclear ophthalmoplegia

what condition is it the first sign of

A
  • Lesion of the medial longitudinal fascicles
  • Palsy of the medial rectus muscle and abducting nystagmus
  • May be unilateral or bilateral
  • First sign of multiple sclerosis
48
Q

what is the aetiology of Inter nuclear ophthalmoplegia in young people and in old people
what condition can mimic INO

A
  • In young people most commonly MS
  • In older people may be due to small vessel obstruction
  • Myasthenia can mimic INO

will refer all these people for systemic investigations

49
Q

what 4 main things happen in a unilateral INO when the px tries to look to the left

A

Loss adduction affects in (one) R eye, including:

  • saccades
  • smooth pursuit
  • VOR
  • OKN
  • Milder forms loss of peak saccadic velocity
  • ABducting nystagmus contralateral eye
  • Lesion discrete convergence retained (even though their adduction is affected)
  • Lesion upper part of MLF = convergence not retained
50
Q

what 4 things happen in a bilateral INO

A
  • Lesions affect interneurones running in the MLF from both VI nerve nuclei
  • Bilateral loss of aDduction (VOR, OKN, saccades smooth pursuit)
  • Abducting nystagmus either eye
  • Limited to interneurones convergence retained
  • Often asymmetric (exo more asymmetric side)
51
Q

what happens in One and a half syndrome INO plus gaze palsy

A
  • Extensive caudal lesion affects horizontal gaze centre (PPRF) and adjacent MLF
  • Loss of aBduction one side
  • Loss of aDduction either side
  • Abducting nystagmus unaffected LR

= a loss of gaze to one side and a failure of adduction

  • CHP to achieve central fixation
52
Q

list all 13 ocular Investigations of supra/internuclear palsies in practice

A
  • Visual acuity
  • Fundus examination - must look at disc for papilloedema
  • 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
  • Investigation of other types of eye movement system
    Convergence
    OKN
    VOR
    Saccades
53
Q

list 2 systemic conditions investigations carries out of supra/internuclear palsies

A

As an optom, will refer px to Hes to determine the aetiology

  • Full medical history
  • Full medical assessment
    Blood tests
    Blood pressure
    EKG
    MRI/CT
    Assessment of 12 cranial nerves
54
Q

list all 5 management options of supra/internuclear disorders

A
  • Immediate referral into the HES
  • Determine aetiology
  • Use CHP to avoid diplopia and oscillopsia (sometimes have to do botox if oscillopsia is a problem)
  • Prisms/ Occlusion to avoid diplopia
  • Cosmetic surgery sometimes possible

Binocular vision YR 3 (20 decks)

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