Neuro-Ophth 2, pupils, gaze and conditions Flashcards
What is Anisocoria?
the presence of asymmeterical pupillary size between the two eyes
physiological or pathological
What is the normal pupil size in light and dark?
2-4mm and 4-8mm
In what % of the population is physiological aniscoria present?
20% of the population
What is unique about physiological aniscoria?
unchanged in light and dark environments
What is horner syndrome caused by?
lesion in the sympathetic pathway
What is horner syndrome characterised by?
Ptosis: mild eyelid droop due to Muller muscle dysfunction
Miosis: dysfunction of dilator pupillae
Ipsilateral facial anhydrosis: not present in third order neurons
Affected iris is lighter in colour
What are some causes of Horner’s syndrome?
first order: lateral medullary syndrome and syrinomyelia
second order: pancoast tumour and neck trauma
third orders: internal carotid dissection (painful), cluster headache and cavernous sinus lesions
What 4 investigations are used in Horner’s syndrome?
Topical apraclonidine
topical cocaine
topical hydroxyamphetamine
CT or MRI
How is topical apraclonidine used in Horner’s syndrome?
used to confirm horner’r pupil
it is an alpha-1 and alpha-2 adrenergic agonist
causes dilation in horner’s pupil due to denervation hypersensitivity
How is topical cocaine used in horner’s syndrome?
used to confirms horner’s pupil
cocaine blocks re-uptake of noradrenaline
causes dilation of normal pupil > than horner’s pupil
How is topical hydroxyamphetamine used in horner’s syndrome?
used to differentiate between preganglionic and post ganglionic horner’s pupils
hydroxyamphetamine releases norepinephrine from normal post ganglionic adrenergic nerve endings, causing pupil dilation
failure of dilation - third order (post ganglionic), dilation - first or second order
How are CT / MRI used in horner’s syndrome?
if tumours / carotid arteries suspected
What is Adie’s pupil?
Unilateral condition characterised by loss of postganglionic parasympathetic innervation to the iris sphincter and ciliary muscle
What are the features of Adie’s pupil?
large pupil
poor response to light
intense pupillary response to near stimuli (miosis)
slow re-dilation
What is light-near dissociation?
pupillary reaction to near stimulus is greater than reaction to light
What is holmes-adie syndrome?
Adies pupil + diminished deep tendon reflex of lower limbs
What investigations are used in Adie’s pupil?
Slit lamp: vermiform movements of pupillary borders
pharmacological: 0.1% (low dose) of topical pilocarpine into both eyes causes constriction of affected pupil due to denervation hypersensitivity
What is an Argyll robinson pupil?
bilateral, irregular small pupils
both pupils do not react to light
constrict normally on accommodation (light-near dissocaition)
What is the most common cause of argyll pupil?
diabetes, previous neuro symphillis
What does homonymous hemianopia with macular sparing looking like?
‘half a donut’ of the visual field is blacked out
What type of visual loss do large pituitary tumours lead to?
chiasmatic
bitemporal superior quadrantanopia –> bitemporal hemianopia
What type of visual loss do craniopharyngiomas lead to?
chiasmatic
bitemporal INFERIOR quadrantopia –> bitemporal hemianopia
also casues growth failure, delayed puberty, headaches, diabetes inspidus, obesity and hypothyroidism in kids
What type of visual field loss doe tuberculum sellae meningiomas lead to?
chiasmatic (affects anterior angle of chiasm)
junctional scotoma
What type of visual field loss do aneurysms cause?
a large ANTERIOR COMMUNICATING ARTERY ANEURYSM –> bitemporal hemianopia
bilateral internal carotid aneurysms –> biNASAL hemianopia as they affect temporal lobes of the chiasm
What can lesions to the optic tract cause?
contralateral incongruous (asymmeterical) homonymous hemianopia
What do lesions of the temporal radiations cause?
contralateral, incongruous superior homonymous quadrantopia ‘pie in the sky’
What do lesions of the parietal radiations cause?
Contralateral incongrous inferior homonymous hemianopia ‘pie on the floor’
What do lesions of the main optic radiations cause?
contralateral incongruous homonymous hemianopia
What do lesions in the occipital cortex cause?
occlusion of calcrine artery of posterior cerebral artery: contralateral, CONGRUOUS, homonymous hemianopia with macular sparing
damage to tip of occipital cortex due to systemic hypoperfusion or following an injury to the back of the head: CONGRUOUS homonymous hemianopic central scotoma
What medical problems cause CNIII lesions?
diabetes, HTN - affect blood supply to nerve
usually pupil sparing
Why are medical problems leading to CNIII damage pupil sparing?
pupillomotor fibres are located superficially, supplied by pial blood vessels
What surgical problems can lead to CNIII lesions?
posterior communicating artery aneurysm, uncal herniation and trauma
NOT PUPIL SPARING
What are the features of CNIII lesions?
ptosis
abduction and dpression of eye in primary position
ophthalmoplegia (only abduction of eye is normal)
dilated pupil and accommodation abnormalties
What are some vascular syndromes of CNIII palsies?
weber syndrome - CNIII palsy, contralateral hemiparesis
benedikt syndrome - CNIII palsy, contralateral hemiataxia and hemitremor (damage to the red nucleus)
nothangel syndrome - CNIII palsy (ipsilateral cerebellar ataxia) (damage to superior cerebellar peduncle)
claude syndrome - benedikt + nothangel
What are some causes of CNIV lesions?
congenital CNIV palsy, closed head trauma and microvascular ischaemia
What are the features of CNIV lesions?
vertical diplopia: worse on walking / looking down
hypertropia: affected eye is higher than the other, worsened on tilting head to ipsilateral shoulder
eye depression is limited, noted on eye adduction
compensatory head posutre to avoid diplopia - contralateral head tilt and face turn
bilateral CNIV palsies may present with depressed chin and posture and crossed hypertropia
What are the 3 steps of the Park-Bielschowsky test for CNIV lesions?
- identify hypermetropic eye in primary position
- eyes are examined in left and right gazes, hypertropia increases on opposite gaze in CNIV palsy (worse on opposite gaze, WOOG)
- Ask patient to fix at a target ahead, assess hypertropia on right and left head tilts, hypertropia improves on contralateral head tilt in CNIV (better on opposite tilt, BOOT)
What are some causes of CNVI lesions?
microvascular ischaemia (most common)
other causes: trauma, idiopathic and ICP
What are some features of CNVI lesions?
HORIZONTAL double vision, worsened on looking at distant targets
esotropia in primary position
limited abduction
What are some syndromes that cause sixth nerve palsies?
Foville syndrome
Millard Gaublar syndrome
Gardenigo syndrome
What is fovile syndrome?
lesion to the inferior medial pons
CNVI palsy
ipsilateral facial numbness
ipsilateral facial paralysis
loss of taste sensation to the anterior two third of tongue
horner syndrome
What is millard-Gublar syndrome?
Lesions to VENTRAL pons
CNVI palsy
Contralateral hemiplegia due to damage to corticospinal tract
ipsilateral CNVII palsy
What is gardenigo syndrome?
Causes: otitis media, mastoiditis or petrositis
unilateral periorbital pain
diplopia
otorrhoea
What is internuclear ophthalmoplegia?
lesion to the medial longitudinal fasciculus due to demyelination or stroke
defective adduction of the eye ipsilateral to the lesions and abducting nystagmus of the contralateral eye
may have horizontal diplopia
What is one and half syndrome?
lesion to the PPRF and MLF on the same side, usually due to stroke
ONLY abduction of the contralateral eye can still occur
What is parinaud syndrome?
lesion to the dorsal midbrain
causes: pinealoma or aqueductal stenosis in children and vascular problems in adults
supranuclear upgaze palsy
lid retraction (collier sign)
convergence-retraction nystagmus
large pupil with light-near dissociation
What is progressive supranuclear palsy?
neurodegenerative disorder
characterised by vertical gaze palsy,
slowing of vertical saccades
postural instability
parkinsonism
What is nystagmus?
involuntary rapid and repetitive oscillation of the eye which can be physiological or pathological
risk of amblyopia in young patients tf. important to correct
What is end point nystagmus?
nystagmus at extreme gaze
Waht is optokinetic nystagmus?
nystagmus due to fast moving objects
Describe congenital nystagmus
horizontal,
pendular / jerky
DISAPPEARS DURING SLEEP
What are some causes of congenital nystagmus?
sensory deprivation (bilateral cataracts)
optic nerve hypoplasia
foveal hypoplasia
Describe latent nystagmus
horizontal and jerky
only present on monocular occlusion (direction is away from the covered eye)
most commonly associated with infantile esotropia
What is convergence-retraction nystagmus?
co-contraction of horizontal muscles on attempted upgaze causing the globe to retract
caused by dorsal midbrain lesions e..g parinaud syndrome
Which EOM is the most powerful?
Medial Rectus
What is upbeat nystagmus?
downward drifting of the eye followed by a fast upward corrective saccade or beat
mainly due to medulla lesions
What is downbeat nystagmus?
upward drifting of eye followed by fast downward corrective saccade
mainly due to lesions at the craniocervical junction such as Arnold-Chiari malformation
What is peripheral vestibular nystagmus?
conjugate, horizontal and jerky nystagmus that occurs due to a vestibular lesion (e.g. labyrinthitis)
slow drifting of the eyes towards the side of the lesions followed by a fast corrective saccade in the other direction
What is myasthenia gravis?
AI condition
affecting post synaptic, nicotinic acetylcholine receptors
leads to muscle fatiguability
When does myasthenia gravis present?
3rd decade of life
female predominance
Which muscles are affected in myasthenia gravis?
voluntary muscles
smaller ones first
What are the features of myasthenia gravis?
ptosis: bilateral, worse at end of day or prolonged upgaze
cogan lid twitch: brief upshoot of the lid elicited by making patient look down then up
diplopia
ophthalmoplegia
fatiguability ad weakness of muscles of facial expression and proximal limb muscles
respiratory depression
What investigations are used for myasthenia gravis?
Ice test
antibodies: anti-AChR antibodiy and anti MUSK
repetitive nerve stimulation (decrement of muscle action potential amplitude)
CT thorax: may reveal thymoma
How is myasthenia gravis managed?
acetylcholinesterase inhibitors e.g. pyridostigmine
steroids
immunomodulators
thymectomy if thymoma
What is myotonic dystrophy?
abnormal muscular relaxation and muscle wasting
AD condition, due to tri-nucleotide repeats on chromosome 19
what are the features of myotonic dystrophy?
inability of muscle relaxation
early-onset cataracts: polychrmatic opacities, Christmas tree cataracts
Ptosis
Ophthalmoplegia
What is Kearns-Sayre syndrome?
mitochondrial inherited myopathy due to deletion of mitochondrial DNA
What does histopathology of kearns-sayre syndrome show
ragged red fibres (increased intramuscular accummulation of mitochondria)
how does kearns-sayre present?
within the first two decades of life
triad:
bilateral, symmeterical ptosis and ophthalmoplegia
pigmentary retionopathy with sale and pepper appearance involving macula
cardiac conduction defects
What is miller fisher syndrome?
variant of Gullain Barre
Anti-GQ1b may be present
Describe the features of miller fisher
tetrad
ataxia
areflexia
ophthalmoplegia
facial diplegia
What is NF1?
AD multisystem disorder
due to mutation in the neurofibromin 1 gene on Chr 17
What are the features of NF1?
cafe-au-lait on trunk commonly
axillary freckling
opthalmic:
- optic nerve glioma
- bilateral lisch nodules (Irish hamartomas)
- plexiform neurofibromas (bag of worms) feeling on the lid
- choroidal naevi: patients with this have a higher risk of choroidal malanoma
What is NF2?
less common than NF1
mutation on neurofibromatin 2 gene on chr 22
What are the features of NF2?
posterior SUBSCAPULAR cataracts
bilateral / unilateral acoustic neuromas causing decreased sensorineural hearing loss, tinnitus and loss of corneal reflex
Meningiomas
What is tuberous sclerosis?
AD multisystem disorder characterised by:
- facial angiofibromas
- ash-leaf spots
- seizures
cognitive impairment
multiple intracranial / retinal astrocytic hamartomas
- glial tumours of retinal fibre layers from astrocytes
- referred to as mulberry lesions due to their multinodular appearance
- -on fundoscopy appear as well-dined elevated creamy white lesions
associations: tuberous sclerosis, neurofibromatosis and retinitis pigmentosa
What is benign essential blepharospasm?
bilateral idiopathic condition characterised by involuntary contraction of the orbicularis oculimuscle due to basal ganglia dysfunction
present in sixth decade of life with female predominance
What is meige syndrome?
blepharospasm and oromandibular dystonia
How is benign essential blepharospasm managed?
artifical tears for dry eyes
botulinum toxin injection to orbicularis oculi
-side effects: ptosis, dry eye, diplopia, lagophthalmos and corneal exposure
surgical myomectomy if these don’t work
