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(2) Tri B - Clinical opthalmology > Week 2 - Neuro 1.3 > Flashcards

Week 2 - Neuro 1.3 Flashcards

1
Q

What are the differential diagnosis of a raised disc?

A

• Compression
• Infiltration
• Congenital optic neuropathies (Leber’s optic neuropathy)
• Toxic optic neuropathies (methanol poisoning)
• Traumatic optic neuropathy

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2
Q

What are orbital compressive lesions and their symptoms?

A

Orbital masses may compress optic nerve and venous drainage

Symptoms:
• Monocular
• Slow, compressive, visual loss
- may be central or diffuse

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3
Q

What are associated signs/symptoms of orbital compressive lesions?

A

• Eyelid oedema
• Proposis
• Extraocular muscle involvement

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4
Q

What affect do orbital compressive lesions have on Pupils, Disc and vasculature appearance?

A

• Pupils : RAPD
• Disc Appearance:
- If anterior lesion, get disc oedema
- If intraorbital / intracanalicular, get disc pallor
• Vasculature not compromised; optic nerve dysfunction and atrophy despite no preceding disc oedema
• May have simple oedema or visible signs of infiltration
• Optocilliary shunt vessels

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5
Q

How are orbital compressive lesions investigated?

A

• Hospital investigations:
MRI and CT conducted if lesion suspected

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6
Q

what are the 3 main types of orbital compressive lesions?

A

• Optic nerve sheath meningioma
• Optic nerve glioma
• Melanocytoma

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7
Q

What is an Optic Nerve Sheath Meningioma?

A

• Benign tumour
• Proliferation of meningoepithelial cells lining the sheath of the optic nerve
• One third of optic nerve tumours
• Mean age of presentation: 40-50yrs
• Female > Male (as are meningiomas elsewhere)

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8
Q

What are Optic Nerve Sheath Meningioma: symptoms/signs?

A

• Painless, slowly progressive monocular visual loss (95% of cases)
• Proptosis (60-90% of cases)

• Disc appearance:
- Optic oedema then atrophy
- Optociliary shunt vessels

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9
Q

How is optic nerve sheath meningioma treated and their complications?

A

• Radiotherapy:
Stability or improvement in up to 94%
Complications:
- Radiation retinopathy
- Pituitary dysfunction

• Surgery:
Biopsy or excision
- Risk of optic nerve trauma and visual loss
- Considered if intracranial extension

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10
Q

What is Optic Nerve Glioma?

A

• Usually pilocytic tumours
• Most common primary tumour of optic nerve

• Most are slow growing and benign
• Some are malignant and more rapidly progressing, causing blindness and death

• 70% detected during first decade of life, 90% by second
• Associated with Neurofibromatosis 1, 10-30% of NF1 have Glioma, 10-70% of Glioma have NF1

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11
Q

What are the presenting symptoms and signs of Optic Nerve Glioma? (no Visual field)

A

Proptosis - 94%
Visual loss - 87%
Strabismus - 27%

Optic disc pallor - 59%
Disc oedema - 35%

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12
Q

What are the signs of optic nerve glioma?

A

• RAPD
• Visual field defect
• Optociliary shunt vessels

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13
Q

How is optic nerve glioma managed in hospital?

A

• Observation if good vision and stable imaging appearance
• Chemotherapy when visual loss severe
• Radiotherapy has a risk of complications including pituitary dysfunction

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14
Q

What is Optic Nerve Melanocytoma?

A

• Pigmented tumour of uveal tract
• Predilection for lamina cribrosa of optic nerve head

• Typically benign composed of melanocytes and melanin and don’t grow
- Rarely become malignant

Presentation:
• Can get optic nerve dysfunction if large but usually a coincidental finding

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15
Q

what are the signs of Optic Nerve Melanocytoma?

A

• Black lesion with feathery edges
• Typically small and don’t grow

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16
Q

What are the complications and treatment of optic nerve melanocytoma?

A

Complications:
- Central retinal vein occlusion
- Malignant transformation

Hospital treatment
- Observation every 6-12months

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17
Q

What are infiltrative lesions, their symptoms and signs?

A

• Infiltration / invasion of optic nerve by neoplastic or inflammatory cells
• Ocular involvement may be presenting feature of systemic disease

• Symptoms:
- Progressive, severe visual loss over days to weeks
- Associated with headache

• Signs
- Retrobulbar infiltration - disc appears normal
- Disc involvement - swollen appearance

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18
Q

What are some of the causes of infiltrative lesions?

A

• Leukaemia
• Lymphoma
• Granulomatous infiltration
- Sarcoidosis, TB, syphilis
• Metastases
- rare but most commonly from breast or lung cancer

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19
Q

How are infiltrative lesions investigated? And why are they done?

A

• MRI of brain and orbits
• CSF analysis
• Screening tests for inflammatory / infective / neoplastic disorders

• Early identification allows life saving treatment
• Palliative care may improve vision if poor prognosis

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20
Q

What is Leber hereditary optic neuropathy?

A

• Hereditary condition characterised by bilateral optic atrophy
• Affects maternal mitochondrial DNA
• Males, 10-30 years

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21
Q

What are Leber Hereditary Optic Neuropathy symptoms/signs?

A

• Ask about family history
• Acute, severe, painless visual loss (<6/60)
• Initially monocular but both involved
• Central / centrocecal visual loss
• RAPD when monocular involvement

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22
Q

What is the disc appearance of Leber Hereditary Optic Neuropathy?

A

• Normal in up to 40%
• Hyperaemia and elevation of disc
• Thickening of peripapillary retina
• Peripapillary telangiectasia
• Tortuosity of medium sized retinal vessels
• Eventual optic atrophy

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23
Q

How is Leber Hereditary Optic Neuropathy managed?

A

• MRI scan to exclude a treatable cause
• Once diagnosed no treatment and visual loss usually permanent

24
Q

What is toxic/nutritional optic neuropathy?

A

• Typical history is of alcohol and/or tobacco excess with neglect of diet
(B vitamins & thiamine
• Can get neuropathy in well nourished individuals with pernicious anaemia or vitamin B12 deficiency

• Other meds associated with conditions include Methanol (antifreeze) Cardiac arrhythmia, breast cancer, tuberculosis and acne mediation.

25
Q

what are the symptoms of toxic/nutritional optic neuropathy?

A

• Chronic (gradual & progressive) or acute, depending upon the cause
• Bilateral and symmetrical
• Painless visual loss
• Dimness of vision

26
Q

What are some signs of toxic/nutritional optic neuropathy?

A

• Affects central vision with central / caecocentral scotoma

initial presentation:
• Optic disc can be normal / mild pallor / hyperaemia
- patients with hyperemic discs, could get small splinter hemorrhages on disc edge
• Mild depression on Amsler fixation target
• Reduced colour vision

Months-years after presentation:
• papillomacular bundle dropout
• temporal disc pallor followed by optic atrophy

27
Q

how is toxic/nutritional optic neuropathy investigated and treated?

A

Investigations of exclusion:
• Fluorescein angiography
• Blood testing
• Electrophysiology
• MRI imaging

Treatment
• Reversal of cause
- Can get reversal of ocular signs if optic atrophy has not progressed too much

28
Q

What is Traumatic optic neuropathy?

A

Optic nerve damage from trauma to head / orbit / globe

Direct traumatic optic neuropathy
• Avulsion of nerve from laceration by bone fragments / foreign bodies
• Direct compression from hemorrhage

Indirect traumatic optic neuropathy
• Shear forces on nerve
• Shear forces on vascular supply

29
Q

What scenarios are found during the examination with Px’s with Traumatic Optic Neuropathy?

A

• Visual loss
- Immediate
- Severe - no perception of light
• RAPD
• Optic disc
- If posterior pathology may appear normal
Eventual atrophy
• Neuroimaging
- Assesses extent of injury and co-morbidity

30
Q

How is Traumatic optic neuropathy managed?

A

• Neuroimaging to assesses extent of injury and co-morbidity
• Therapy controversial
• Prognosis poor
• Intravenous steroids

• Anti-inflammatory and neuroprotective
- Increased risk of mortality when combined with other head injuries
- Consider when isolated injury with no other evidence of head injury

31
Q

What are other conditions that cause the APPEARANCE of a raised optic disc? (non-intraocular disease)

A

• Optic disc drusen
• Tilted optic disc
•Myelinated nerve fibres
• Hypermetropic crowded disc

32
Q

What are other conditions that cause the APPEARANCE of a raised optic disc? (intraocular disease)

A

• Central retinal vein occlusion
• Posterior uveitis
• Posterior scleritis
• Hypotony

33
Q

What is optic disc drusen and their symptoms?

A

• Calcified nodules within optic nerve head
• 0.34% - 2% of population
• Bilateral in 75%
• Unclear pathophysiology - ? Impaired ganglion cell axonal transport
• Buried in childhood, more prominent with age

• Symptoms
Most patients asymptomatic

34
Q

What might be found during the ocular examination with drusen in visual fields and RAPD?

A

• Visual fields
- Visual field loss in 75 - 87%
- Enlarged blind spot / arcuate defect
- Remains stable or very slowly preogresses

• RAPD
- Possible RAPD if monocular/asymmetric

35
Q

What might be found during the ocular examination with drusen in the optic disc?

A

• Appears small in diameter
• Anomalous branching vascular patterns
• Round, whitish, yellow refractive bodies
• Disc may be pale / atrophy /RNFL loss

36
Q

What is the difference between buried drusen vs swollen disc and how can they be told apart?

A

Both may elevate the disc and blur its margins, however:-

Optic disc drusen:
• Lack of hyperaemia
• Lack of microvascular changes
• Normal / atrophic nerve fibre layer
• Anomalous retinal vascular patterns

B-scan, Fluorescein angiography and MRI can be used to differentiate between them

37
Q

How is optic disc drusen treated?

A

• None! More dangerous to remove than to just not treat.

38
Q

What is a tilted optic disc?

A

• 1-2% of the population
• 80% bilateral
• Congenital or associated with myopia
• Oblique insertion of optic nerve
• Normal vision

39
Q

How does the disc appear during examination of Tilted optic disc?

A

• Oval, tilted appearance
• Inferior peripapillary atrophy

40
Q

How does the visual field appear during examination of Tilted optic disc?

A

• Can have Bitemporal loss
• Superior arcuate scotoma

41
Q

What are myelinated nerve fibres?

A

• 1% of population
• The nerve fibres are myelinated within the optic nerve and the myelin sheath usually stops at the lamina cribrosa
• Unilateral in 80%

42
Q

What are the signs and symptoms of myelinated nerve fibres?

A

• Symptoms
Usually asymptomatic

• Signs
- Funds examination: Visible yellow patch of myelin around nerve head
- Visual fields: enlarged blind spot corresponding to area of myelin

43
Q

What the types of excavated optic disc anomalies?

A

• Optic disc pit
• Colobomas
• Optic nerve hypoplasia
• Morning glory disc anomaly

44
Q

What is an optic disc pit and what can it cause?

A

• Congenital (failure of foetal fissure)
• Depression of disc surface
• Associated with visual field defect
Risks:
• Serous macular detachment
- Communication between optic pit and macula
- Liquified vitreous or subarachnoid fluid
- Greyish appearance, temporal / inferior disc
• Associated central vision loss when situated on maculopapular bundle

45
Q

How is optic disc pit managed in the hospital?

A

• Difficult, however Options include:
- Observe (25% spontaneously resolve, some develop macular involvement)
- Argon laser along temporal aspect of disc
- Pars plana vitrectomy (air / fluid exchange with posturing)

46
Q

What is a coloboma?

A

• Congenital defect from incomplete closure of the embryonic fissure
- Unilateral or bilateral
- Usually occur inferiorly

47
Q

What are the Visual acuity, visual fields and fundus findings during an examination of coloboma?

A

• Visual acuity
- Reduced

• Visual Fields
- Superior field defect
- Can mimic glaucomatous loss

• Fundus
- Larger than normal optic discs
- Can involve uvea and retina

48
Q

What are some associations and complications of coloboma?

A

• Associations
- Microphthalmos
- Colobomas of iris, choroid, retina

• Complications
- Serous / rhegmatogenous retinal detachment
- Progressive neuroretinal rim thinning

49
Q

What is optic nerve hypoplasia?

A

• Reduced number of nerve fibres In isolation (by chance), part of malformed eye or associated with:
• Midline structures of the brain
• Endocrine abnormalities - growth hormone and other pituitary hormones
• Suprasellar tumours

50
Q

What are optic nerve hypoplasia predisposing factors?

A

• Diseases;
- Maternal diabetes,

• Drugs and Agents; (agents ingested by mother during pregnancy)
- alcohol, LSD, quinine, steroids, diuretics, anticonuuissants, cold remedies…

51
Q

How does Optic nerve hypoplasia present in bilateral and unilateral cases?

A

Bilateral cases:
• Nystagmus eye movements
• Sluggish pupil responses
Less severe bilateral cases:
• Squint
• Minor visual field defects

Unilateral cases:
• Squint
• RAPD
• Unsteady fixation in affected eye

52
Q

What are the visual field and disc findings during the examination of optic nerve hypoplasia?

A

• Visual Fields
Peripheral and arcuate defects

• Disc appearance
- Small diameter of disc
- Grey disc colour and surrounding hypopigmentation
- Relatively large retinal vessel diameter
- Ratio of disc diameter:disc-fovea >3:1

53
Q

How is optic nerve hypoplasia managed in hospital?

A

• MRI in all cases
• Referral for endocrine opinion

54
Q

What is the morning glory anomaly?

A

• Rare congenital malformation, embryonic origin unclear
• Funnel-shaped staphylomatous excavation of the optic nerve
• Usually unilateral
• More common in females

55
Q

What are the visual field and fundus findings during examination of Morning glory anomaly?

A

• Visual acuity <6/60
• RAPD
• Visual field loss
• Serous retinal detachment

• Fundus
- Enlarged disc
- Disc pink or orange colour
- Chorioretinal pigmentation around excavation
- White glial tissue on central disc surface
- Retinal vessels appear at periphery of disc

(2) Tri B - Clinical opthalmology (10 decks)

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