Week 2 - Neuro 1.3 Flashcards
What are the differential diagnosis of a raised disc?
• Compression
• Infiltration
• Congenital optic neuropathies (Leber’s optic neuropathy)
• Toxic optic neuropathies (methanol poisoning)
• Traumatic optic neuropathy
What are orbital compressive lesions and their symptoms?
Orbital masses may compress optic nerve and venous drainage
Symptoms:
• Monocular
• Slow, compressive, visual loss
- may be central or diffuse
What are associated signs/symptoms of orbital compressive lesions?
• Eyelid oedema
• Proposis
• Extraocular muscle involvement
What affect do orbital compressive lesions have on Pupils, Disc and vasculature appearance?
• 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
How are orbital compressive lesions investigated?
• Hospital investigations:
MRI and CT conducted if lesion suspected
what are the 3 main types of orbital compressive lesions?
• Optic nerve sheath meningioma
• Optic nerve glioma
• Melanocytoma
What is an Optic Nerve Sheath Meningioma?
• 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)
What are Optic Nerve Sheath Meningioma: symptoms/signs?
• Painless, slowly progressive monocular visual loss (95% of cases)
• Proptosis (60-90% of cases)
• Disc appearance:
- Optic oedema then atrophy
- Optociliary shunt vessels
How is optic nerve sheath meningioma treated and their complications?
• 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
What is Optic Nerve Glioma?
• 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
What are the presenting symptoms and signs of Optic Nerve Glioma? (no Visual field)
Proptosis - 94%
Visual loss - 87%
Strabismus - 27%
Optic disc pallor - 59%
Disc oedema - 35%
What are the signs of optic nerve glioma?
• RAPD
• Visual field defect
• Optociliary shunt vessels
How is optic nerve glioma managed in hospital?
• Observation if good vision and stable imaging appearance
• Chemotherapy when visual loss severe
• Radiotherapy has a risk of complications including pituitary dysfunction
What is Optic Nerve Melanocytoma?
• 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
what are the signs of Optic Nerve Melanocytoma?
• Black lesion with feathery edges
• Typically small and don’t grow
What are the complications and treatment of optic nerve melanocytoma?
Complications:
- Central retinal vein occlusion
- Malignant transformation
Hospital treatment
- Observation every 6-12months
What are infiltrative lesions, their symptoms and signs?
• 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
What are some of the causes of infiltrative lesions?
• Leukaemia
• Lymphoma
• Granulomatous infiltration
- Sarcoidosis, TB, syphilis
• Metastases
- rare but most commonly from breast or lung cancer
How are infiltrative lesions investigated? And why are they done?
• 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
What is Leber hereditary optic neuropathy?
• Hereditary condition characterised by bilateral optic atrophy
• Affects maternal mitochondrial DNA
• Males, 10-30 years
What are Leber Hereditary Optic Neuropathy symptoms/signs?
• Ask about family history
• Acute, severe, painless visual loss (<6/60)
• Initially monocular but both involved
• Central / centrocecal visual loss
• RAPD when monocular involvement
What is the disc appearance of Leber Hereditary Optic Neuropathy?
• 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
How is Leber Hereditary Optic Neuropathy managed?
• MRI scan to exclude a treatable cause
• Once diagnosed no treatment and visual loss usually permanent
What is toxic/nutritional optic neuropathy?
• 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.
what are the symptoms of toxic/nutritional optic neuropathy?
• Chronic (gradual & progressive) or acute, depending upon the cause
• Bilateral and symmetrical
• Painless visual loss
• Dimness of vision
What are some signs of toxic/nutritional optic neuropathy?
• 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
how is toxic/nutritional optic neuropathy investigated and treated?
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
What is Traumatic optic neuropathy?
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
What scenarios are found during the examination with Px’s with Traumatic Optic Neuropathy?
• 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
How is Traumatic optic neuropathy managed?
• 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
What are other conditions that cause the APPEARANCE of a raised optic disc? (non-intraocular disease)
• Optic disc drusen
• Tilted optic disc
•Myelinated nerve fibres
• Hypermetropic crowded disc
What are other conditions that cause the APPEARANCE of a raised optic disc? (intraocular disease)
• Central retinal vein occlusion
• Posterior uveitis
• Posterior scleritis
• Hypotony
What is optic disc drusen and their symptoms?
• 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
What might be found during the ocular examination with drusen in visual fields and RAPD?
• 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
What might be found during the ocular examination with drusen in the optic disc?
• Appears small in diameter
• Anomalous branching vascular patterns
• Round, whitish, yellow refractive bodies
• Disc may be pale / atrophy /RNFL loss
What is the difference between buried drusen vs swollen disc and how can they be told apart?
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
How is optic disc drusen treated?
• None! More dangerous to remove than to just not treat.
What is a tilted optic disc?
• 1-2% of the population
• 80% bilateral
• Congenital or associated with myopia
• Oblique insertion of optic nerve
• Normal vision
How does the disc appear during examination of Tilted optic disc?
• Oval, tilted appearance
• Inferior peripapillary atrophy
How does the visual field appear during examination of Tilted optic disc?
• Can have Bitemporal loss
• Superior arcuate scotoma
What are myelinated nerve fibres?
• 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%
What are the signs and symptoms of myelinated nerve fibres?
• Symptoms
Usually asymptomatic
• Signs
- Funds examination: Visible yellow patch of myelin around nerve head
- Visual fields: enlarged blind spot corresponding to area of myelin
What the types of excavated optic disc anomalies?
• Optic disc pit
• Colobomas
• Optic nerve hypoplasia
• Morning glory disc anomaly
What is an optic disc pit and what can it cause?
• 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
How is optic disc pit managed in the hospital?
• 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)
What is a coloboma?
• Congenital defect from incomplete closure of the embryonic fissure
- Unilateral or bilateral
- Usually occur inferiorly
What are the Visual acuity, visual fields and fundus findings during an examination of coloboma?
• Visual acuity
- Reduced
• Visual Fields
- Superior field defect
- Can mimic glaucomatous loss
• Fundus
- Larger than normal optic discs
- Can involve uvea and retina
What are some associations and complications of coloboma?
• Associations
- Microphthalmos
- Colobomas of iris, choroid, retina
• Complications
- Serous / rhegmatogenous retinal detachment
- Progressive neuroretinal rim thinning
What is optic nerve hypoplasia?
• 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
What are optic nerve hypoplasia predisposing factors?
• Diseases;
- Maternal diabetes,
• Drugs and Agents; (agents ingested by mother during pregnancy)
- alcohol, LSD, quinine, steroids, diuretics, anticonuuissants, cold remedies…
How does Optic nerve hypoplasia present in bilateral and unilateral cases?
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
What are the visual field and disc findings during the examination of optic nerve hypoplasia?
• 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
How is optic nerve hypoplasia managed in hospital?
• MRI in all cases
• Referral for endocrine opinion
What is the morning glory anomaly?
• Rare congenital malformation, embryonic origin unclear
• Funnel-shaped staphylomatous excavation of the optic nerve
• Usually unilateral
• More common in females
What are the visual field and fundus findings during examination of Morning glory anomaly?
• 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