Supranuclear Palsies

Question 1

what are the two principles of eye movement

Answer 1

keeping image steady on the retina

e.g. vestibular

optokinetic

pursuit

fixation

those that change the line of sight , acquire an image and hold it on the fovea - so that both eyes are looking at the target stimulating the fovea to get binocular single vision

e.g. saccades and vengeances

Question 2

what pathways are involved in saccades

Answer 2

there are parallel pathways that converge on the brainstem from the frontal cortex and the posterior parietal cortex they descend and end with a signal at the pprf - the signal decussates and gets to the pprf - that is what generates horizontal saccades

Question 3

what structures are inolved in horizontal saccades

Answer 3

pathways from frontal eye fields

parietal cortex, and superior colliculus

pathways decussate and terminate in the pprf

stimulation of the frontal eye fields results in

conjugate movement to the contralateral side

if you stimulate the left frontal eye field then you will get a saccade to the right

Question 4

what structures are involved in vertical saccades

Answer 4

pathways from the frontal eye fields

pathway descends to rimlf in the mid brain

bilateral stimulation of the frontal eye fields results in vertical saccades- conjugate movement to the contralateral eye

Question 5

what are the slow eye movement pathways

Answer 5

smooth pursuit , vestibular , optokinetic system , vergences

Question 6

what structures are involved in smooth pursuits

Answer 6

Pareto occipital temporal junction is important - pathway is important because it changes two times (double decussation) - so clinically people say it is under ipsilateral control

Question 7

vestibular ocular reflex ( What structures are involved)

Answer 7

vestibular - information comes from the semicircular canals (information comes from the inner ear)

ipsilateral horizontal vestibular nuclear complex (this is where the signals get to)-that relays information to the contralateral 6th nerve nucleus

vestibular eye movements to the contralateral side

Question 8

optokinetic system

Answer 8

head rotation

system that initiates sustained head rotation and when we stop spinning - nucleus of the optic tract (in the brainstem) is important

Question 9

what structures are important in vergence eye systems

Answer 9

pretectal nuclei = important

pathway= runs with 3rd cranial nerves

Question 10

what are supranuclear pathways

Answer 10

how to the signals get to the cranial nerve nuclei

Question 11

what are the different possible sites of lesions

Answer 11

supranuclear pathways ( supranauclear)

cranial nerve nuclei (nuclear) - internuclear- between cranial nerve nuclei

infra nuclear pathway (course of nerve) is infra nuclear

neuromuscular junction

extraocular muscle

globe

Question 12

what happens when you get a lesion above the level of the nucleus

Answer 12

a lesion above the level of the nucleus

resulting in gaze palsies

horizontal

vertical

global paralysis

i..e you can’t make a horizontal gaze or a vertical gaze

Question 13

what type of gaze tends to be affected in a supranuclear palsy

Answer 13

conjugate gaze tends to be affected
i.e. both eyes not looking into the positon

diplopia is often not a problem because both of the eyes are doing the same thing

lesions can be paralytic , destructive , irratative

complete/partial

Question 14

what are the different types of lesions causing supranuclear palsies

Answer 14

parlaytic/ destructive/ irritative

complete/partial
paralytic lesion meaning there is a complete failure of function - and the eyes deviate towards the side of the lesion

irratative lesion = increase in stimulation of affected area

eyes deviate to the opposite side of the lesion

Question 15

what are signs of frontal lesions

Answer 15

drowsiness/impaired concious rate

Question 16

what are signs of unilateral frontal lobe lesions

Answer 16

unable to perform saccades

• affeceting the frontal eye filed so saccadic signals are disrupted

paralytic lesion - visual hemineglect to the same side as the lesion

Question 17

if you had a right frontal lobe lesion what would be affected

Answer 17

right frontal lobe lesion = failure of saccades to the left

Question 18

in bilateral frontal lobe lesions what would you expect to see

Answer 18

you wouldn’t be able to make saccades to either side

vor (which is a reflex movement) will be intact

so you need to compare saccades to VOR to distinguish between bilateral and unilateral frontal lobe lesions

Question 19

what will happen if you have a occipital lobe lesion

Answer 19

you will have a contralateral visual field defect

unilateral lesion results in contralateral hemianopia and saccadic Dysmetria in direction of the visual field defect

bilateral lesions result in cortical blindness

Question 20

what is a right hemianopia caused by

Answer 20

right homonymous hemianopia can’t see anything on right visual deed and is caused by left occipital lobe lesion

Question 21

what does a unilateral lesion of the partial occipital lobe cause

Answer 21

failure of smooth outset and to affected side - pt wont be following the target properly - but will be aware that the image slips off the fovea

leads to retinal slip and catch up saccades

repeated catch up saccades

cogwheel pursuits

look for cog wheeling

saccadic dymetrica- hyp oand hypermetric

vor intact more of a reflex movement

vr defect is likely- because the occipital Lobe is intact

Question 22

what are subcortical lesions

Answer 22

lesions affecting pathways between the cortex and the pprf

Question 23

what are the types if subcortical lesions

Answer 23

global paralysis

horizontal gaze palsy

vertical gaze palsy

Question 24

what is global paralysis

Answer 24

roth bielshowsky syndrome

loss of all movements

saccades/smooth pursuits

dolls head test and vestibular nystagmus = normal

pons = intact

lesion = small lesion In the upper midbrain

where saccade and pursuit pathways come together

lesion = diffuse bilateral hemispheric lesions = including the brainstem

Question 25

what are the different types of lesion causing horzizontal gaze palsy and what to they csue

Answer 25

lesion before deccusation loss of conjugate gaze to the contralateral side lesion in the basal ganglia - parlaytic lesion = parksinsons disease / Huntingtons disease irratative lesion = oculogyric lesion (eyes roll back into head) lesion at decussation loss of movement to both sides lesion below decussation (in pons) loss of conjugate movement to the ipsilateral side cranial nerve , 3 , 6, 7, 8 can also be involved

Question 26

describe the horizontal gaze pathway

Answer 26

fibres descend from the frontal eye fields through the basal ganglia decussating just above/ at the top of the pons - descend though the pons to the PPRF

Question 27

what lesions cause a horizontal gaze palsy

Answer 27

lesion in the ipsilateral pprf /6th nerve nucleus acquired pprf lesion partial pprf lesion bilateral pprf lesion acquired nuclear 6th nerve plays congenital horizontal gaze palsy oculomotor aphaxia

Question 28

what happens in in a nuclear 6th palsy

Answer 28

you get a 6th nerve palsy and a gaze palsy so gaze needs to be looked at to determine weather it is a nuclear or infarnuclear palsy

Question 29

what is affected in a horizontal gaze palsy

Answer 29

right gaze palsy and a left gaze palsy - they cannot look right or left but they can converge - if the eyes look very limited but then you test convergence and the eye movements suddenly look a lot better - that suggests that the lesion is supranuclear and it is not a mechanical problem that the eyes dont move that way

Question 30

why is it important to test convergence

Answer 30

if convergence is intact suggests that there is a high likelihood that it is a suprnucelar p palsy could be at the level of ducessation i.e. the pons (pontine lesion)

Question 31

what are the features of an acquired pprf lesion

Answer 31

an acquired pprf lesion chronic =- total horizontal gaze plasy to the ipsilateral side so a right pprf lesion will give you a right horizontal gaze palsy can be acute = partial restriction of horizontal gaze

Question 32

what are features of a partial pprf lesion

Answer 32

gaze preference to the contralateral side saccades to the ipsilateral side = infrequent and small amplitude/slow nystagmus when attempt to look towards the affected side gaze paretic nystagmus - eyes fail to maintain eccentric gaze

Question 33

what are features of bilateral pprf lesions

Answer 33

if you have a lesion that takes out both pprf you will not be making any fast eye movements right to left ateiology can be vascular = incomplete, tend to recover tumour?primary/metatstic degenerative = including PSP

Question 34

what are features of an acquired 6th nerve nucleus lesion

Answer 34

you will have a gaze palsy to the ipsilateral side convergence will be intact but because the 6th cranial nerve is quite close to the 7th cranial nerve careful attention to ensure facial palsy is not occurring aswell usually a metastatic cause and it is quite rare that it is vascular

Question 35

what is a congenital horizontal gaze palsy

Answer 35

usually they have a total absence of horizontal gaze associated with spinal abnormalities ateioology is usually unknown ? aplasia (underdevelopment) of 6th nerve nucleus and MLF CCDD

Question 36

what is oculomotor apraxia

Answer 36

selective horizontal gaze palsy absent voluntary horizontal saccades reflex induced horizontal saccades = normale vertical saccades and pursuit movements= normal blink and head jerks/thrusts used to change fixation manoeuvre pts adopts/learns to innate saccades tend to become more accurate to view target - blink - use head thrust intact vor- eyes moved and positioned on target ateiology- being, bilateral FEF lesions , corpus callous lesion , acquired (balints syndrome) bilateral frontal/ front partial lesions

Question 37

what structures are important in making vertical gaze

Answer 37

vertical gaze plays usually related to lesions of the posterior composure rostral interstitial nucleus of the MLF (riMLF) bells phenomenon and vertical dolls head test should be intact (more of a reflex movement) upgaze reduces with age - so need to consider what his a significant reduction of elevation

Question 38

how to test bells phenomena

Answer 38

when the eyelids are being forced closed the eye should roll upwards underneath the eyelid - you are asking them to screw there eyelids up tight and forcing the lids open to see if you can see weather the eyelids go up If the eyelids go up then bells phenomena is intact if the eyes do not then bells phenomena is not intact -

Question 39

how to do a vertical dolls head test

Answer 39

you grab the head and make it go up and down - the movement of the head is being detected by the inner ear and the eyes are moving in response to the vestibular system

Question 40

what conditions cause vertical gaze palsy

Answer 40

progressive supranuclear palsy (psi) defective vertical scales and progressive loss of vertical movements - can't moves eyes up and down oculogyric crisis loss of balance ateiology extreme brain degeneration progressive until death

Question 41

what does progressive supranuclear palsy need to be differentially diagnosed from

Answer 41

Parkinson's disease defective upgaze and slow vertical saccades absent impairment of downsize hutingtons chorea defective saccades on upgaze (in early part of saccade)

Question 42

what is parniauds syndrome

Answer 42

can cause a vertical gaze plays also known as dorsal midbrain syndrome loss of upgaze saccades/ smooth pursuits / vor and dolls head / bells phenomena on attempted upgaze = lid retraction and convergence retraction nystagmus lid retraction on downgaze (colliers sign) convert weakness if progressive = downsize weakness (saccades/sm pursuit/vor) light / near dissociation of the pupils ?skew deviation paipillodema acute stage= ''setting sun sign'' (associated with hydrocephalus)

Question 42

what is the light near dissociation response

Answer 42

they typically have mid dilated pupils with no reaction to light but when you show them near target and you get them to accommodate the pupils do constrict - differential needs to be made between a light stimulus for the pupils and an accomodative target for the stimulus which can be tested during convergence - so you are watching to see if the pupils constrict

Question 43

what its papillodema

Answer 43

swollen optic discs

Question 44

what is the ateiology of parinauds

Answer 44

lesion in the region if the sylvan aqueductt in the upper dorsal midbrain pineal gland tumour pinealoma can compress superior colliculus ?obstructive hydrocephalus - flow of css gets blocked and they have high icp

Question 45

what are features of a vertical gaze palsy caused by hydrocephallus

Answer 45

these are infants with raised icp, the eyes do not look up and are fixed in downgaze - sometimes referred to are setting sun sign and the aetiology is something that is blocking the flow of csf- they have an obstructive hydrocephalus and get an increased amount of pressure in the third ventricle - the outflow area gets blocked or they have a space occupying lesion causing a hydrocephalus- they dont have fixed cranial sutures so they will usually have quite large heads

Question 46

describe the features of a double elevator palsy

Answer 46

usually associated with a supranuclear ateiology and is a type of vertical gaze palsy may have a secondary mechanical restrictions / inferior rectus contracture this is where they have a limitation of one eye - usually unilateral (bilateral is very rare) usually congenital - acquired is rare in primary position NAD/ hypotonia have chin elevation ptosis or psudopotsis suprancular palsy- intact bells and vert VOR

Question 46

what is the ateiology of a supranuclar palsy

Answer 46

suprnauclear lesion in dorsal midbrain nuclear lesion is unlikely = ipsilateral inferior oblique and contralateral superior rectus total paralysis of the Superior Rectus usually genetic

Question 47

what are the aims of the investigation

Answer 47

examine each ocular movement system diagnose any failures of the systems propose the possible sites of the lesions document findings repeat assessment regularly to monitor progress

Question 48

what extra tests needed to be included when testing supranuclear testing

Answer 48

observation - ptosis general history ocular history symptoms gh previous ocular history va ct om - all systems pupils spinning caloric irrigation bells phenomena vf innattention tests colour vision contrast sensitivity eye movement recordings

Question 49

what further investgations need to be done

Answer 49

ophthalmological , medical and neurological investigations available car plan and prognosis developed after considering ateiology of condition gh presence/ absence of symptoms ability to regain fusion (investigating bsv and potential bsv) previous treatment presence of ahp

Question 50

what is the role of the orthoptist

Answer 50

investigation diagnosis monitoring coniiditon conservative managment options prism therapy ahp - advice/information head movements occlusion to eliminate diplopia excerices adaptation ptosis props