DIS - Optic Nerve III - Week 10 Flashcards
Do inherited neuropathies always manifest at birth?
no, they may not manifest until later in life
What is the major acquired optic neuropathy?
Glaucoma
Define neuropathy.
Ongoing and premature loss of optic nerve fibres beyond normal ageing
What is the end point of any neuropathy?
Atrophy
Differentiate between papilloedema and optic disc oedema.
Papilloedema - bilateral swollen discs due to raised intracranial pressure
Optic disc oedema is generalised oedema with many other causes
Describe the timeline of acute and chronic neuropathy to atrophy (3 each).
Acute - disc oedema, vascular compromise, necrosis > optic atrophy
Chronic - apoptosis, loss of nerve fibres, cupping/pallor > optic atrophy
Describe the stages of disc oedema by the amount of disc involved (3).
Partial
Sectoral
Total
Describe the stages of disc oedema by the visibility of vessels and structures (2).
Early - majority of structures visible
Severe - obstructed view
Compare the appearance of acute and chronic disc oedema.
Acute - messy
Chronic - clean, champagne cork
List five tests that assess optic nerve function.
Swinging flashlight test
Monocular vision
Monocular colour vision loss (ishihara)
Colour comparison - red cap
Brightness comparison (max brightness on ophthalmoscope, same principle as red cap testing)
Are inherited optic neuropathies common or rare? Are they easily diagnosed or commonly misdiagnosed?
Rare and often misdiagnosed
List the three main modes of inheritence for inherited optic neuropathies.
Autosomal recessive
Autosomal dominant
Mitochondrial
In what three ways could other cases be ruled out for inherited optic neuropathies.
Serology
Imaging
Dilated fundus exam
What mode of inheritence does Behrs syndrome have and how does it affect vision and from what age?
Autosomal recessive
Profound vision loss in neonates
What appearance does the disc have in behrs syndrome?
Chalky white disc
True or false
Nystagmus is not present with behrs syndrome
False, it is
Can a foveal reflex be seen with behrs syndrome?
No
What colour deficiency is present with behrs syndrome?
Red-green
List three systemic abnormalities of behrs syndrome.
Spastic gait
Ataxia
Mental handicap
What mode of inheritence does wolfram syndrome have?
Autosomal recessive
What kind of atrophy does wolfram syndrome have?
Diffuse severe optic atrophy
What is DIDMOAD and what disease is it for?
Diabetes insipidus
Diabetes mellitus (type 1)
Optic atrophy
Deafness
For wolfram syndrome
List four systemic associations of wolfram syndrome. How does it affect lifespan?
Ataxia
Short stature
Endocrine anomalies
Mental impairment
Short lifespan
What mode of inheritence does kjers disease have?
Autosomal dominant
What effect does kjers disease have on vision and at what age?
Mild chronic loss
How does the optic disc appear with kjers disease and what area specifically?
Temporal disc pallor
What kind of visual field defect occurs with kjers disease?
Relative central scotoma
What colour deficiency does kjers disease cause?
Blue-yellow
Are other neurological abnormalities common with kjers disease?
Uncommon
What is the most common inherited optic neuropathy?
Kjers disease
What is the most common mitochondrial disorder?
Lebers hereditary optic neuropathy
Between males and females, which is more affected by lebers hereditary optic neuropathy?
Males
How does lebers hereditary optic neuropathy affect vision?
Profound vision loss in young adults from 6/24 to NLP
What kind of visual field defect is present with lebers hereditary optic neuropathy?
Absolute central scotoma
What colour vision defects are present with lebers hereditary optic neuropathy (2)?
Early blue-yellow then red-green defects
What happens to the optic nerve with lebers hereditary optic neuropathy?
Normal disc > optic atrophy with time
How does the optic disc margin appear with lebers hereditary optic neuropathy initially?
Initially circumpapillary telangiectasia
What is the treatment for inherited optic neuropathies?
Often no treatment, so focus on assistance for legally blind individuals
How should patients with positive family history for inherited optic neuropathies be managed? What about negative? What else should be considered (2)?
Positive - refer for genetic counselling
Negative - refer for serology and imaging
Manage systemic issues (diabetus/endocrine)
Vocational guidance - colour vision deficiency
What is the normal ICP in the supine and upright positions?
Supine - 5 to 15mmHg
Upright 2 to 10mmHg
How is raised ICP typically diagnosed?
Lumbar puncture - invasive and painful
What is the most common cause of raised ICP?
A mass such as a tumour, haemorrhage, abcess, or oedema
List four things that can increase venous pressure.
Coughing
Valsalva manoeuvre
Heart failure
Jugular vein obstruction
Blockage to what two structures can cause altered CSF flow and subsequently raised ICP?
Blockage in the ventricles or subarachnoid space
-results in hydrocephalus
What two thing may result in increased CSF production.
Meningitis
Tumour
List four causes of raised ICP aside from mass.
Increased venous pressure
Altered CSF flow
Increased CSF production
Idiopathic intracranial hypertension
What is pseudotumour cerebri?
Idiopathic intracranial hypertension
Where can compression of the visual pathway occur?
Intracranially
Intraorbitally
What is foster-kennedy syndrome? What does this syndrome present the only case of? Explain why this is so.
One eye has compressive neuropathy
Fellow eye has papilloedema
-only case where papilloedema is not bilateral
-this is because an atrophic optic nerve is no longer able to manifest the optic disc oedema
List three causes of foster-kennedy syndrome.
A mass in the following regions:
Frontal lobe
Olfactory groove
Sphenoid wing meningioma
List 9 neurological signs of foster-kennedy syndrome.
Severe/different constant headaches (sudden onset, thunderclap)
Gait problems (unsteady)
Projectile vomiting/nausea
Hemiparesis
Reduced alertness/consciousness
Brief visual disturbances (~30s)
Diplopia
Symptoms worse with posture change
Back/neck pain
Is pupil abnormality a sign of foster-kennedy syndrome?
Yes
How do intracranial masses raise ICP? Why does the RNFL swell?
They are a space-occupying lesion, and raised ICP is transmitted along the subarachnoid space, to the lamina
Compression at the lamina causes axoplasmic stasis, causing swelling
Aside from affecting the nerves, what else is affected with compression along the optic nerve? Most markedly which region and why? What happens to the disc and nearby blood vessels?
Compression along the optic nerve gives venous compromise
Most markedly inferior due to gravity
Disc hyperaemia and buried blood vessels can be seen
What happens to the veins specifically with venous compromise due to optic nerve compression (consider SVP)?
Venous engorgement
-no SVP with digital pressure
What happens to the peripapillary region with venous compromise due to optic nerve compression?
Peripapillary haemorrhages
Can cotton wool spots be seen with venous compromise due to optic nerve compression?
Yes
What is a cotton wool spot?
Nerve fibre layer infarct
Can papilloedema be seen with venous compromise due to optic nerve compression?
Yes
What can changes can be seen on the retina and choroid with venous compromise due to optic nerve compression?
Retinal or choroidal folds
What is an initial sign of compressive neuropathy?
Mild disc oedema
List four long term signs of compressive neuropathy.
Compensated with established shunts
Champagne cork clean appearance
Gross intravitreal swelling of the ON
Venous flow not compromised, but axoplasmic stasis still present
How does the retina appear with non-compensated compressive neuropathy?
Very dirty looking with haemorrhage and cotton wool spots
List 8 other causes of papilloedema.
AIDS
Congenital hydrocephalus
Hypertension
Infectious meningitis
Inflammatory neuritis
Trauma
Aneurysm or haemorrhage
Idiopathic
What is an aneurysm?
Abnormal swelling or bulging in a blood vessel wall
What is the mortality of aneurysms or haemorrhages? Are they an emergency?
50%
-is an emergency
Why is the location of major cerebral blood vessels important in the context of how aneurysms and haemorrhages affect vision?
They often involve the visual pathways, either directly or through transmitted ICP
List four signs of an impending aneurysm rupture.
Thunderclap headache
Photophobia
Vision loss
Back/neck pain
How long does it generally take for a rupture to occur (give range) and what is the median length?
1 day to 4 months
-median 14 days
What 7 signs should you look for when suspecting an aneurysm or haemorrhage?
Vision loss
Pupil involvement
Lid anomaly
Extraocular muscle palsy
ON atrophy (with/without cupping)
Papilloedema
Intraorbital haemorrhage
What should you beware when suspecting aneurysm or haemorrhage?
Head/brow/orbital pain that doesnt fit a recognised pattern
What demographic does pseduotumour cerebri typically affect (3)?
Premenopausal obese women
What are the signs of pseudotumour cerebri (3)?
As per papilloedema
-all investigations fail to find a cause (MRI/CT/LP)
-few neurological signs aside from severe headaches (90%)
What percentage of pseudotumour cerebri have severe vision loss?
15 to 25%
What can pseudotumour cerebri with CN6 involvement result in?
Double visiond
What kind of diagnosis is pseudotumour cerebri?
Diagnosis by exclusion
How should patients with suspected pseudotumour cerebi be managed?
Refer to the hospital for urgent medical workup
What is the prognosis like for pseudotumour cerebri?
Good if ICP is reduced
List 7 treatment options for pseudotumour cerebri?
Diuretics
Repeated lumbar puncture
Carbonic anhydrase inhibitors
Steroids
Weight reduction
Surgical shunting of CSF to jugular
Optic nerve decompression
When assessing compressive neuropathies, what should you do and look out for? What three neurological tests should you do?
Dilated fundus exam for comprehensive ONH evaluation
Visual fields
Ocular motility
Pupil testing
When should papilloedema be referred? How should they be monitored? What should be measured?
Urgent referral to GP or neuro-ophthalmologist within 1 week
Monitor daily to see if anything develops
Measure blood pressure
What should you do if you see papilloedema with neurological signs?
Emergency referral to the hospital
What should you do with patients with chronic unexplained pain with compressive neuropathy? What about acute,severe, and sudden onset?
Non-urgent referral to a neuro-ophthalmologist
If acute, severe, sudden onset - emergency referral
