Neuro Ophthalmology Flashcards
What are the 2 different visual pathways controlling pupil reactions?
Sympathetic- Dilator
Parasympathetic- sphincter
When is the pupil at its max dilation and minimum constriction?
Dilation- apprehensive in the dark
Constriction- bored while sunbathing
What is the primary driver of pupil light responses?
Parasympathetic pathway
What is the process from afferent to efferent response?
The afferent section allows RGCs light signals to reach midbrain (Edingerwest phal nucleus). This is responsible for generating afferent to efferent constriction signal.
What does the sympathetic pathway contributes to?
Light response via activation of dilatory muscle
Where does the sympathetic pathways passes over in the body?
Sites that exposes nerve fibre to local and systemic diseases i.e. lung tumours and internal carotid artery
What conditions do not give rise to an RAPD?
- Cataracts
- Amblyopia
- Visual pathway lesions post to Chiasm
When is it an exception for a post to the chiam lesionto cause an RAPD?
If more in 1 eye than the other, INCONGROUS homo hemiamopia or quadrantanopia
When is an RAPD caused?
If there is an imbalance in strengths of right and left afferent signals
What conditions that are associated with RAPD?
- Anterior Ischaemic Optic Neuropathies (Arteritic or non Arteritic?
- Optic Neurits
- Advanced glaucoma
- Unil ON tumour
- Tumours compressing ON
- Unil ON Trauma
- Orbital disease
What are key signs for an RAPD to be present?
Unilateral and Aysmmetric VF defects
Also depends on degree and depth/extent
Which area is effected to cause AION or NA AION?
Short posterior ciliary arteries
What tumours may cause an RAPD?
Meninginoma, pituitary lesion, ON glioma
What are the conditions that show a normal reacting pupil?
- Physiological anisocoria
2. Horners syndrome
What are the conditions that show an abnormal reacting anisocoia?
- Adies tonic pupil
2. 3rd nerve palsy
What are the signs of a physiological anisocoria and how common is it?
15-20% of the population Asymptomatic
Normal vision
No GH association
No ptosis
Which pathway is effected in horners syndrome?
Sympathetic pathway
What are the causes of horners syndrome?
- Brainstem damage
- Carotid or Aorotic artery dissection
- ‘Pancoast tumour’ (Apical lung tumour)
Where are the potential pathologys located to cause horners syndrome?
- Sup cervical symp ganglion
- Internal carotid artery
- Long ciliary nerve
- Ciliary ganglion
What symptoms are likely to be seen in an carotid artery dissection?
HAs Numbness/weakness Neck and shoulder pain (If ophthalmic artery effected- Amarausis fugax) Painful acute horners syndrome
What is a carotid artery dissection?
A tear in the internal artery wall
What are the ocular signs of horners syndrome?
- Miosis
- Ptosis
- Anhidrosis
Which muscle has reduced innervation in ptosis?
Superior or inferior tarsal muscles
If both upper and lower tarsal muscles were seen to have reduced innervation, what may this be misdiagnosed as?
Endophthalmos
What symptoms are there in horners?
No ocular/visual symptoms
What us Annhydrosis?
Drying of the skin on the same side as the sympathetic nerve fibres
…also runs along carotid artery and arise parasympathetic nerve fibres damaged
Management on horners syndrome…
… sudden onset horners= urgent!
Pharmacological pupil testing and imaging
If a involvement of the pupil is absent in a 3rd nerve palsy, what features are expected?
Other features of 3NP but light reflexes remain intact
What is the meaning of partial total and absent mean in 3NP?
Partial- dilated with sluggish direct
Total- fixed dilated (no direct response
Absent- normal light reflexes
What are the 2 oculomotor signs when checking for 3NP?
Cover test and ocular motility
Ptosis
What position is the eye in, in 3NP and what muscles would be effected?
Down and out = u/a medial rectus
Depressed= SR, IR and IO u/a
Ptosis= u/a levator muscle
What are the ocular symptoms presented in 3NP?
- Hz, vz, oblique binocular sudden dip
- Intermittent dip- subtle fusion reserves still present
- Constant dip- significant lack of EOM innervation
- No dip sxs- ptosis complete
- Significant pupil involvement(glare/photophobia)
- Possible Non ocular sxs depending on pathology.
What are the non ocular symptoms in 3NP?
- HAs/orbital facial pains
- GCS sxs
- CVA sxs
- Demylinating disease sxs
What are the potential causes to 3NP?
- Compressive lesions (tumour)
- Ischaemic (interruption to 3NP blood supply)
- Inflammatory (Multiple sclerosis)
Which is the most common cause of 3NP?
Ischaemia
What is the pathway the 3rd nerve goes to get to the eye?
The 3rd nerve start MIDBRAIN, passes through the CAVERNOUS SINUS sinus which is close to INTRACRANIAL STURCTURES I.e. circle of Willis, pituitary gland.
Once entering the orbit, 3rd nerve splits into 2 branches: superior and inferior branch
What muscles are supplied by the 3rd nerve in the superior and inferior branch?
Superior- SR and levator
Inferior- MR, IR and IO
What structures do the 3rd nerve follow to reach the iris sphincter and ciliary muscle?
INFERIOR OBLIQUE… then the fibres enter the CILIARY GANGLION where the SHORT CILIARY NERVES supply these structures
Where would a lesion responsible for 3NP more commonly found?
Posterior to the orbit
How is a 3NP managed?
Acute= emergency referral (same day phone call)
… include CT/MR fo risk of intracranial pathology
Which muscles is the 4th nerve supply?
Superior oblique
What are the risk factors of ischaemia?
DM
HT
GCA
What are the signs of 4NP?
- Incomitant ipsilateral hypertropia (elevation)
- Deviation greater in adduction
- Compensating head tilt (away)
- Torsional deviation
What are the sxs of 4NP?
Acute- sudden vz, torsional, oblique diplopia
Head tilt minimises effect
Poss longstanding
What can cause 4NP?
Commonly CONGENITAL and UNILATERAL
Acquired (compressive/ ischaemic/inflamm path)
Trauma- head injury
How is 4NP managed?
Acute- emergency referral
Congenital- non urgent (if no previous investigation)
Which muscle is effected in 6NP?
Lateral rectus muscle
What are the signs of 6NP?
Sudde onset SOT Head turn (towards effected side) Poss VF defect
What are the ocular sxs of 6NP?
Sudden Hz dip (max when effected eye adducts, dip greater at Dist)
Asthenopia
Reduced corneal sensitivity (if trigeminal nerve involved)
What are the possible non ocular sxs of 6NP?
HAs/ pain around eye/ nausea
Facial numbness/pain
Masticulation disorder
Hearing loss
What are the possible causes of 6NP?
Any/all vasc/comp/inflamm
More susceptible to COMPRESSIVE damage due to ICP
Why makes 4NP more vulnerable to damage?
Its a thin and long pathway (midbrain to SO)
Located/passes over petrous temporal bone
Which other cranial nerves could be effected by he 6NP?
5th (Trigeminal nerve)- reduced facial sensation
8th (auditory nerve)- acoustic neuromas
What is the management for 6NP?
Acute= emergency referral
CT/MR scans needed
If a bitemporal NP is present, what would the lesion be effecting?
Pan cranial (whole head) i.e. ICP, Meningitis, demylinating disease
Which structure would be effected to damage multiple cranial nerves?
Cavernous sinus
What can midbrain or pons lesions give rise to?
- Intranuclear ophthalmopegia
- Supranuclear ophthalmopegia
- Acquires Nystagmus
- Myasthenia Gravis
What is INO responsible for where is it located?
Gaze control centre and is found in the 6th nerve nucleus
What sxs are associated with INO and when are these sxs worse?
Diplopia
Oscillopsia (unstable visual world, no balance)
Worse when looking in side gaze
What is the most common cause for INO and SNO?
Midbrain pathology
What is the key feature of SNO?
Difficulty with eye movements
Can’t look UP and RIGHT
What is the management for SNO and INO?
Emergency referral
How are majority of nystagmus formed?
Congenital
Maybe caused by mid brain lesion
What is myasthenia gravis?
Autoimmume disease which muscular functions are reduced via neuromuscular junctions.
What other condition can this may appear as?
A nerve palsy, hard to differentiate but end result is the same
What are the signs of myasthenia gravis?
Ptosis (bilateral and assymetrical)
Motility defects
Diplopia (unless ptosis complete)
As MG is a systemic condition what sxs could be present?
Change in facial expression Difficulty swallowing Shortness of breath Impaired speech Limb weakness
How is MG managed?
Pharmacological treatment?
Referred- non urgently via GP
What tests are carried out to help dx and compare optic neuropathies?
VF VA Colour vision Pupil reaction Sxs ONH Assessment
What are the 2 main signs/sxs of the presence of opic neuropathy?
- Acquired colour vision defect
2. Disc swelling/ pseudo swelling
What colour vision test would detect a red/green deficiency and a tritan defect?
Ishihara colour vision test- red/green deficiency
City test- tritan defect
What is the key point in acquired color vision defects?
That there are likely going to be sxs
What is a key feature of congenital color vision defect?
Its bilateral
What does the nature of the defect depend on?
Cone type effected by the RNFL
ONH pathology
Which benign conditions mimic disc swelling?
Optic disc drusen
Crowded optic disc
Tilted disc
Disc pseudo swelling
What are the signs and onset of disc drusen?
Congenital- visible in teen yrs Bilateral and Assymetrical 75% Asymptomatic Normal VA VF- irregular pattern possible
What is the referral criteria for optic disc drusen?
Irregular VF pattern present or unsure= non urgent referral to rule out papilloedema
What is another name for crowded optic disc?
Congenital optic disc hypoplasia
What is “bunching up” referring to?
RNF passing through small apertures in small diameter discs
What is associated with tilted discs?
Myopia
Astimatism
VF loss
What type VF loss is present in a tilted disc?
Commonly bitemporal and superior and does no respect vz midline (mimics a chiasmal lesion)
What are the signs of disc pseudo swelling?
- No blurring of RNFL
- No obstruction of opic disc blood vessels
- Cup intact
- No dilation of disc arteries/veins
- No flame haemm at disc margins
- No syst/ocular sxs related to GCA, ICP, Demylinating disease
What leads to acute ischaemia of the ONH?
Sudden reduction in blood flow in the posterior ciliary artery
How does acute ischaemia effect the RNFL?
Causes infarction
What other pathology is acute ischaemia similar to?
Retinal artery occlusion
Why is acute ischaemia different to chronic ischaemia?
This is a slow starvation I.e. conditions like DM retinopathy
Where is the ischaemia located?
Posterior to the lamina cribrosa
What happens to retinal nerves during ischaemia?
Sudden painless loss of function. Also referred as stroke of optic nerve
Whatis the single biggest risk factor for AION?
Age
What are the sxs of AION?
Unilateral, sudden painless loss of vision Amarausis fugax (intermittent transient vasc occl)
What are the signs of AION?
- Decreased colour vision
- Marked RAPD
- VF Altitudinal and unil loss (inferior attitudinal common)
- Disc appearance- pale disc, oedema and hypereamia from swelling, splinter haemm
How long does the oedema and hyepreamia resolve?
6/52
What do AAION and NA AAION both have in common?
- Acute and chronic disc appearance
- VA loss
- RAPD
- VF defects
What is the key difference between AAION and NA AION?
Sxs assco c GCA
How is AAION caused?
Inflamm leading to vasc occl of the post ciliary artery
What are the potential risk factors for NA AAION?
Systemic vasc factors Arteriosclerosis High BP High cholesterol level DM SMOKERS!
What makes PION different to AION?
PION arteries effected are found far posterior b/w ON and chiasm- disc appears normal but will show other signs of AION.
How are ION managed?
Acute= emergency
Recent hx of Amarausis fugax= same day phone call
GCA sxs but no other sxs= Emergency
What is optic neuritis?
Inflammation of the RNF (not the blood vessels!!!!)
What is the cause of optic neuritis?
Demyelinating disease
What is demylinating disease?
Autoimmune disorder where nerves looses the myelin sheath and disrupt neural transmit
What is the age group that are at risk of ON?
15-45 years
What is the key difference between AION and ON?
Age!
Early age onset- ON
Later stage onset- AION
What are the sxs of ON?
- Episodic
- Sudden blurred vision
- Pain on eye movements
As the ON condition is episodic what is the time scale for the blurred vision to dissipitate?
Increases over 2/52 and slowly improves over 4/52
What 2 conditions can cause ON?
Multiple sclerosis
Epstein bar virus
Between makes and females c ON, what is the likely chance of developing MS?
66% females
33% men
ON is the 1st sign of what?
Multiple sclerosis
What are the sxs of MS?
All episodic: Numbness Pins and needles Muscle spasm Limb pain
What are the signs of MS?
Reduced VA
Reduced colour vision
VF defect
RAPD
What is the disc appearance of ON?
Normal in 66% during and after episodes
Of inflammation retro bulbar- signs are subtle
33% show mild-mid unil disc OEDEMA and HYPEREAMIA
How is optic neuritis managed?
Same day phone call
HES will assess approx 1/52
Why are the RGCs unmylinated?
Minimise shadow effects induced on underlying retinal layers
What can a myelin sheath look like?
Cotton wool spots
Where do myelin sheaths start and end ?
At the midbrain- LGN and end at the lamina cribrosa
How is a myelin sheath managed?
No referall necessary
Inform and reassure px
Document size and position
What is papilloedema?
Disc swelling in presence of ICP
How can papilloedma be confirmed?
Neuroimaging and lumbar puncture
What causes ICP?
- Idiopathic IC Hypertension
- Intracranial space occupying lesion
- Decreased CSF drainage
Name some conditions that would cause decreased CSF drainage?
Meningitis
Hydrocephalus
Subarachnoid papilloedema
What is IIH strongly associated with?
Obesity (90%)
What are the sxs of ICP?
HAs
Postural element
Other neurological sxs
What are the ocular signs of papilloedema?
Disc swelling (from axoplasmic build up)
Dilated and haemm disc vessels (ischaemia)
VF Defects (presence depends on severity)
VA and colour vision reduced (recovery possible)
How is papilloedema managed?
Suspected?= potential emergency
Any signs and sxs c no disc swelling= Emergency
Persistent HAs and other neurogical sxs= Advise to see GP if all else normal
What are the sxs of amarausis fugax?
Monocular vision loss Painless Whole VF effected Last several minutes= <1hr-<10mins Described- 'dim, black, spreading in one direction
What is the common cause of amarausis fugax?
Transient acute retinal ischaemia induced by carotid disease
What are the other causes for amarausis fugax?
Papilloedema and migraines
In what form is permanent vision loss precuror to?
CRAO, BRAO and AAION
If signs are not present in Amarausis fugax, what action is taken?
Seek medical advise and ask px about strokes sxs
What is the most common type of visual defect when thinking about strokes?
Homonymous hemianopia
What is the 1st and 2nd most common lesion locations to cause VF defect?
1st- occipital lobe
2nd- Parietal lobe
What are the actions take for potential stroke VF defects?
- New hemianopia c other strokes sxs (<1/52)— Emergency via A+E
- Symptomatic hemianopia c no other steoke sxs (>1/52)— urgent outpx and seen <1/52- 10 days
- Asymptomatic hemianopia and VF defect incidental finding—- GP appointment (traige c stroke team)
What is visospatial neglect and how is it managed?
One side of the vision is ignored (usually opposite side of the brain injury)— ROUTINE REFRRAL
What is a thyroid eye disease?
Autimmune disorder causing inflammation of orbital fat tissue and EOM
Who are at risk of thyroid eye disease?
Age 40-50 yrs
F>m
What does thyroid eye disease lead to?
Proptosis- a retraction of the upperlid
What are the sxs of proptosis?
Constant intermm diplopia
Dry eye
What are the signs of proptosis?
VF defect
Bilateral or unilateral
How is proptosis managed?
Non urgent referral via GP
