DIS - Optic Nerve III - Week 10 Flashcards by B H

Do inherited neuropathies always manifest at birth?

no, they may not manifest until later in life

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What is the major acquired optic neuropathy?

Glaucoma

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Define neuropathy.

Ongoing and premature loss of optic nerve fibres beyond normal ageing

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What is the end point of any neuropathy?

Atrophy

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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

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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

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Describe the stages of disc oedema by the amount of disc involved (3).

Partial
Sectoral
Total

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Describe the stages of disc oedema by the visibility of vessels and structures (2).

Early - majority of structures visible
Severe - obstructed view

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Compare the appearance of acute and chronic disc oedema.

Acute - messy
Chronic - clean, champagne cork

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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)

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Are inherited optic neuropathies common or rare? Are they easily diagnosed or commonly misdiagnosed?

Rare and often misdiagnosed

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List the three main modes of inheritence for inherited optic neuropathies.

Autosomal recessive
Autosomal dominant
Mitochondrial

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In what three ways could other cases be ruled out for inherited optic neuropathies.

Serology
Imaging
Dilated fundus exam

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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

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What appearance does the disc have in behrs syndrome?

Chalky white disc

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True or false
Nystagmus is not present with behrs syndrome

False, it is

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Can a foveal reflex be seen with behrs syndrome?

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What colour deficiency is present with behrs syndrome?

Red-green

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List three systemic abnormalities of behrs syndrome.

Spastic gait
Ataxia
Mental handicap

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What mode of inheritence does wolfram syndrome have?

Autosomal recessive

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What kind of atrophy does wolfram syndrome have?

Diffuse severe optic atrophy

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What is DIDMOAD and what disease is it for?

Diabetes insipidus
Diabetes mellitus (type 1)
Optic atrophy
Deafness
For wolfram syndrome

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List four systemic associations of wolfram syndrome. How does it affect lifespan?

Ataxia
Short stature
Endocrine anomalies
Mental impairment
Short lifespan

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What mode of inheritence does kjers disease have?

Autosomal dominant

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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