Neuro-ophthalmology Flashcards
What is skew deviation?
• Supranuclear disorder due to disruption of vestibular input to brain stem responsible for vertical eye movements (cranial nerve 3 and cranial nerve 4)
• Arises from cerebellar or brainstem pathology
• Often manifests as weakness of bilateral inferior rectus muscles → alternating hypertropia (right hypertropia with right gaze; left hypertropia with left gaze) → localizes to cervicomedullary junction
• Associated with downbeat nystagmus
• “Upright-supine test” = hypertropia measured in upright position then again in supine position. In skew deviation, profound reduction in hypertropia when lying supine. No reduction in patients with cranial nerve 4 palsy
What is the difference between congenital nystagmus and latent nystagmus?
• Congenital nystagmus: slow phase velocity accelerates over time
• Latent nystagmus: slow phase velocity either constant velocity or decelerating velocity
What was the optic neuritis treatment trial and its findings?
• Patients with first episode of optic neuritis, evaluated within 8 days of symptoms onset
• 65% had retrobulbar optic neuritis (no papillitis)
• 35% had anterior optic neuritis (papillitis)
• Randomized to (1) Intravenous steroids (Solu-Medrol 250mg q6h x 3 days) followed by oral prednisone 1mg/kg/day x 11 days then quick taper (2) Oral prednisone 1mg/kg/day x 14 days (3) Placebo
• All groups has excellent visual recovery without difference in visual outcome at 6 months
• Steroid treatment (IV and PO) reduced risk of MS in first 2 years after treatment
• PO prednisone group → higher rate of recurrence than both the other groups
• IV steroid group → least likely to progress to MS at 2 years
• Overall 50% of patients with optic neuritis developed clinically definite MS over next 15 years
• Overall optic neuritis is presenting symptom in 25% of MS patients
• Major predictor for risk of progression to MS = presence of one or more white matter lesions on MRI of brain
• 25% risk of MS in the next next 15 years if no lesions on MRI
• 72% risk of MS in the next 15 years if 1 or more lesions on MRI
Which diseases are associated with vascular compression induced neuropathy by aberrant, ectatic, or dilated intracranial artery compressing on cranial nerve?
• Superior oblique myokymia
• Trigeminal neuralgia
• Hemifacial spasm
What is superior oblique myokymia?
• Most common cause: idiopathic
• Other causes: neoplasm, vascular, acquired
• Irritation of cranial nerve 4
• Spontaneous firing of superior oblique on one side causing “jumping” of vision in one eye (high frequency, low amplitude oscillation) and binocular diplopia
• MRI can show vascular compression of 4th cranial nerve on affected side
What is trigeminal neuralgia?
• Unilateral facial pain described as electric shock-like
• Transient, duration lasting seconds to minutes
• Main cause is vascular compression (superior cerebellar artery) of trigeminal nerve
• Treatment: spacer (sponge) between trigeminal nerve and superior cerebellar artery
What is hemifacial spasm?
• Usually unilateral
• Abnormal spasms of facial muscles supplied by cranial nerve 7
• Causes: stroke, demyelination, tumors, AVMs, idiopathic
• Common etiology: vascular compression of facial nerve root by distal branches of anterior inferior cerebellar artery or vertebral artery
• Work up: MRI brain, rule out CPA tumor
• Treatment: botox, microvascular decompression surgery
What is benign essential blepharospasm?
• Bilateral
• Episodic contraction of orbicularis oculi muscles
• Related to underlying basal ganglia dysfunction
• Many have functional or stress related comp• onent
• Exacerbated by corneal surface disease (dry eye)
• Treatment: botox
What is the differential diagnosis for alternating hypertropia?
• Skew deviation: right hypertropia with right gaze; left hypertropia with left gaze
• Bilateral cranial nerve 4 palsy: right hypertropia with left gaze; left hypertropia with right gaze
• Partial cranial nerve 3 palsy (if right sided): left hypertropia with upgaze and right hypertropia with down gaze
• Bilateral inferior rectus restriction (thyroid-associated ophthalmopathy): Left hypertropia on right gaze; Right hypertropia on left gaze
What is Riddoch phenomenon?
• In cortical blindness, ability to see moving targets but unable to see any stationary targets
What is Anton syndrome?
• Patient with cortical blindness that is in denial of their blindness
What is Pulfrich phenomenon?
● Illusion that an object is moving perpendicular to persons line of sight that is usually moving towards or away from them
● Seen after recovering from optic neuritis
○ Due to relative conduction delay within optic nerve that has been affected by demyelinating optic neuritis compared to contralateral unaffected optic nerve
What is Charles Bonnet syndrome?
• In a patient with severe bilateral visual loss of any type (i.e. macular degeneration, glaucoma, cortical blindness)
• Leads to formed and unformed visual hallucinations
• Patient is aware hallucinations are not real
What are the most common visual abnormalities associated with optic disc drusen?
• Visual field defects (75%-90%): most commonly enlarged blind spot
• Transient visual obscurations (5-10%) due to transient optic disc ischemia
What are the ocular findings in Parkinson’s disease?
• Apraxia of eyelid opening
• Square wave jerks
• Convergence insufficiency
• Blepharospasm
• Dry eye
• Decreased blink rate
What is the ocular effect of progressive supranuclear palsy?
• Vertical saccades predominantly
What is ocular neuromyotonia?
• Spasms of some or all muscles supplied by cranial nerves 3, 4, or 6
• Episodic binocular diplopia
• Lasts seconds to minutes
• Due to tonic discharges of offending cranial nerve related to some sort of prior insult (radiation, surgery, etc)
• Treatment: carbamazepine, gabapentin
What is autosomal dominant optic atrophy?
• Most common hereditary optic neuropathy (1 in 50,000)
• Presents in the first 10 years of life but can present much later
• Mutation of OPA1 gene on chromosome 3 → interrupts mitochondrial membrane integrity and function
• Visual acuity range 20/40 to 20/100
• Temporal optic atrophy
• Maculopapular bundle defects
• Central and cecocentral scotoma
• Blue dyschromatopsia (tritanopia)
What visual field (VF) defects are associated with mild to moderate temporal pallor?
• Associated with many different VF defects, including isolated central visual field defects
What percentage of the general population has physiologic anisocoria?
• Approximately 20%
• Usually <1 mm difference in pupils
• Anisocoria symmetric in light and dark or slightly greater in the dark
What work up should be done for optic nerve hypoplasia?
• MRI brain
• Endocrine evaluation
What are optic nerve drusen?
• Proteinaceous nodules that become calcified
• As the drusen progress towards nerve fiber layer → block axoplasmic flow → progressive visual field defects
• Disrupt normal architecture of retina and nerve head → can cause choroidal neovascular membrane formation
• <10% have transient visual obscurations lasting seconds due to transient ischemia of optic nerve head
What is the differential diagnosis for optociliary shunt vessels (retinochoroidal collaterals)?
• Optic nerve sheath meningioma
• Optic nerve glioma
• Chronic papilledema
• Chronic glaucoma
What is the definition of optociliary shunt vessels (retinochoroidal collaterals)?
• Dilation of naturally occuring veins that drain from peripapillary retinal circulation into choroidal circulation
• Shunt vessels occur in response to chronically poor drainage of central retinal vein
What are the findings in cranial nerve 6 nucleus lesion?
• Ipsilateral abduction defect and contralateral adduction defect due to interneuron connection with contralateral MLF
• Any lesion affecting 6th cranial nerve nucleus almost always causes ipsilateral facial palsy
What are the ocular findings and etiology of ethambutol toxicity?
• Optic neuropathy in approximately 1.5% of patients who use it
• Mitochondrial toxicity of retinal ganglion cells RGCs → RGCs whose axons decussate in the chiasm are more susceptible to mitochondrial toxicity
• Bitemporal hemianopia and cecocentral pattern on visual field
• Early decrease in color vision and visual acuity
What are the most common causes of retrochiasmal visual loss adults and children?
• Adults: stroke (60%), trauma (10%), hemorrhage (10%)
• Children: trauma and tumors
What is downbeat nystagmus?
• Abnormal drift of eyes upward followed by corrective downward fast saccade
• Most pathology localizes to cervicomedullary junction or vestibulocerebellum
• Seen with Arnold-Chiari I malformation
What is morning glory disc?
• Congenital
• Unilateral
• Females > males
• MRI/MRA brain should obtained in all patients with morning glory disc
3 associations:
• Serous RD
• Transsphenoidal basal encephaloceles -mimic nasal polyps on exam
• Moyamoya disease: bilateral stenosis or occlusion of arteries around circle of Willis (chronic progressive cerebrovascular disease)
What is digoxin toxicity-related chromatopsia?
• Yellow or yellowish green hue throughout visual field
• Reversible with cessation of decreased or decreased dose of drug
• Can occur despite “normal” serum level of digoxin on lab testing
• ERG: cone dysfunction
What is sildenafil-related chromatopsia?
• Blue chromatopsia
What is the cause of convergence-retraction nystagmus?
● Seen in dorsal midbrain syndrome (aka Parinaud’s syndrome)
○ Abnormal co-contraction of medial and lateral rectus muscles on attempted upgaze
○ Not rhythmic
○ Does not have fast or slow phase
○ Does not involve abnormal drift from fixation
○ Elicited by holding down going OKN drown
What are the ocular effects of methanol and ethylene glycol toxicity?
• Occur immediately after ingestion
• Devastating acute, diffuse vision loss with associated optic disc edema
What are the most common causes of chronic toxic and nutritional neuropathy?
Toxic:
• Ethambutol
• Ethanol
• Chloramphenicol
• Hydroxyquinolones
• Penicillamine
• Cisplatin
• Vincristine
Nutritional deficiency:
• Vitamin B12
• Folate
• Thiamine
What is latent nystagmus?
• Develops early in life
• Likely occurs from early disruption of binocular vision
• Common in children with infantile strabismus
• Asymptomatic for most patients
• Can result in poor visual acuity on monocular vision testing
• Bilateral jerk nystagmus that generally only manifests upon occlusion on one eye
• Fast phase of nystagmus beats towards viewing eye
What is FLAIR MRI?
• Subset of T2
• Attenuates bright signal of CSF allowing for better visualization in periventricular regions adjacent to CSF (i.e. multiple sclerosis)
What is DWI MRI?
• Diffusion weighted imaging
• Highlights recent vascular perfusion abnormalities (i.e. recent stroke)
What is T1 MRI?
• Best for visualization of anatomy
• Fat is bright
• CSF, vitreous, and air are dark
What are square wave jerks and their common causes?
• Type of saccadic intrusion
• Lack fast or slow phase
• Small amplitude
• Bilateral small horizontal shifts from fixation during examination followed by pause and then quick return to fixation
Common causes:
• Cerebellar dysfunction
• Parkinson’s disease
• Supranuclear palsy
What is polyopia?
• Seeing 3 or more images
• Unilateral monocular polyopia → functional or optical
• Bilateral monocular polyopia → migraine, epilepsy, stroke
• Often functional but when organic it is due to disturbance of occipital lobes, accompanied by homonymous VF defect
What is the sympathetic pathway to the eye?
• Axons never decussate
• First order neuron: from posterior lateral hypothalamus, descend through brainstem to intermediolateral cell column between C7 and T2 where they synapse with cell bodies of second order neurons
• Second order sympathetic neurons project from intermediolateral cell column between C7 and T2 to paravertebral sympathetic chain where fibers ascend to superior cervical ganglion and synapse with third order neurons
• Third order neuron cell bodies lie in superior cervical ganglion and pass superiorly into cranial cavity with the internal carotid artery (ICA) along wall of artery (carotid plexus). Ocular sympathetics continue with ICA as it passes in cavernous sinus. While in cavernous sinus, third order axons travel from ICA to abducens then join nasociliary branch of V1. Then travel with nasociliary V1 into orbit and through ciliary ganglion to extend to dilator muscle
What are the causes of first-order Horner syndrome?
• Wallenberg (lateral medullary syndrome)
• Thalamic hemorrhage/stroke
• Tumors
• Cervical disease
• Demyelination
• Pathology of cervical spinal cord
What are the causes of second-order Horner syndrome?
• Pancoast tumor or apical lung malignancies
• Brachial plexus injuries
• Thoracic surgery with disruption of superior portion of paravertebral sympathetic chain
What are the causes of third-order Horner syndrome?
• Internal carotid artery pathology (dissection)
• Cavernous sinus compressive or inflammatory lesions
• Trigeminal autonomic cephalgia type headache
What are low flow dural sinus fistulas?
• Abnormal connection between small dural based arteries and cavernous sinus
• Occur spontaneously without inciting event
• Can resolve spontaneously without surgical intervention
• Clinical findings: elevated IOP, proptosis, ocular motor palsy, arterialization, injection of conjunctival vessels, choroidal effusions, ischemic optic neuropathy, and pain
What are high flow carotid-cavernous fistulas?
• Usually traumatic origin
• Cranial bruit
• Abnormal connection between internal carotid artery and cavernous sinus
• Require urgent angiography with thrombosis
• Clinical findings: elevated IOP, proptosis, ocular motor palsy, arterialization, injection of conjunctival vessels, choroidal effusions, ischemic optic neuropathy, and pain
How does one test ocular ductions?
• Test ocular motility under monocular conditions
How does one test ocular versions?
• Test ocular motility under binocular conditions
What are the causes of bilateral small pupils?
• Opioid narcotics
• Increasing age
• Chronic tonic pupils (initially large, shrink over time)
• Parasympathomimetic (i.e. use of pilocarpine)
• Sleep
• Pontine hemorrhages
What hormone is most commonly deficient in septo-optic dysplasia?
• Growth hormone
What are the causes of infiltrative optic neuropathy?
• Optic nerve gliomas
• Leukemia
• Lymphoma
• Sarcoidosis
• Syphilis
• TB
• Fungal
• Meningeal-carcinomatosis
What is ocular dysmetria?
• Overshoot or undershoot of eyes upon refixation to new target
• Suggestive of cerebellar pathology
What is the inheritance and what mutations are involved in Leber’s hereditary optic neuropathy?
• Maternally inherited disease
• Mitochondrial dysfunction
• Point mutations in mitochondrial DNA
• >90% cases due to 11778, 14484, and 3460 mutations
What is Wolfram syndrome?
• Autosomal recessive or sporadic
• Diabetes insipidus plus diabetes mellitus plus optic atrophy plus sensorineural deafness
What is Behr syndrome?
• Variant of autosomal recessive optic atrophy
• Associated neurologic abnormalities: ataxia, pyramidal and extrapyramidal dysfunction, hypertonia, intellectual disability, urinary incontinence, pes cavus
What is the most accurate means of quantifying afferent pupillary defect?
• Neutral density filters
What is one-and-a-half syndrome?
• Internuclear ophthalmoplegia with ipsilateral horizontal gaze palsy
• Etiology: stroke of pontine region (includes MLF, PPRF, cranial nerve 6 nucleus)
What is the cause and presentation of ERM-induced diplopia?
• Caused by dragging of the fovea in the affected eye
• Prisms are ineffective
• ERM peel often ineffective because fovea does not return to physiologic location
What is Duane retraction syndrome and what are the different types?
• Congenital eye movement disorder
• Agenesis or dysgenesis of 6th cranial nerve nucleus
• Type 1: abnormal abDuction (one D)
• Type 2: abnormal aDDuction (two D’s)
• Type 3: both abDuction and aDDuction (three D’s)
What is the presentation of diabetic papillopathy?
• Mild optic neuropathy
• Minimal visual manifestations
• Optic nerve with telangiectasia
• Most common in older patients with diabetes mellitus type 2
• Visual field with enlarged blind spot
• Fluorescein angiogram: leakage without rising into vitreous
What is the presentation of junctional scotoma?
● Ipsilateral side with central vision loss and contralateral deficit in superotemporal field
● Compressive lesion localized to optic nerve junction with anterior chiasm(Willbrand’s knee)
○ Willbrand’s knee = inferonasal retinal ganglion decussate in optic chiasm, before entering contralateral optic tract, they loop anteriorly for short segment in to contralateral optic nerve
○ Ipsilateral optic nerve compromise results in central scotoma
What are the causes of decreased and increased IOP in ocular ischemic syndrome (OIS)?
Causes of decreased IOP
• Hypoperfusion to ciliary body
Causes of elevated IOP
• Hemorrhages in anterior chamber or vitreous
• Angle closure from neovascularization of angle
• Reperfusion IOP spike after carotid endarterectomy
What is Weber syndrome?
• Midbrain lesion affecting cranial nerve 3 and cerebral peduncle
• Cranial nerve 3 palsy
• Contralateral hemiparesis
What is Benedikt syndrome?
• Lesion in midbrain affecting cranial nerve 3, red nucleus, and substantia nigra
• Cranial nerve 3 palsy
• Contralateral “rubral” tremor (slow tremor present with activity and rest)
What is Claude syndrome?
• Damage to dorsal midbrain
• Affecting superior cerebellar peduncle and cranial nerve 3
• Cranial nerve 3 palsy and contralateral ataxia
What are the causes of posterior ischemic optic neuropathy?
• Hypoperfusion
• Anemia
• Poor cardiac output
• Hypovolemia
• Cardiopulmonary instability
• Rare causes: giant cell arteritis, SLE, polyarteritis nodosa, VZV
What are the clinical findings associated with optic nerve pits?
• Visual acuity is normal (unless serous macular RD)
• Serous macular RD 25-75%
• Associated with nerve fiber bundle visual field defects (arcuate scotoma)
What is Sherrington’s law?
• Monocular principle
• Increased contraction of the innervated muscle results in equal relaxation the antagonist muscles
What is Hering’s law?
• Binocular principle
• Equal and simultaneous innervation of yoke muscles
• Violation of this law → dissociated vertical deviation (DVD); dissociated horizontal deviation (DHD); spread of comitance
What is the most commonly involved cranial nerve in neurosarcoidosis?
• Most common is cranial nerve 7
• Second most commonly involved is cranial nerve 2, including disc edema secondary to meningeal infiltration or optic nerve perineuritis or optic nerve infiltration
What is the differential diagnosis for the combination of uveitis and facial nerve palsy?
• Lyme disease
• Sarcoidosis
What is the anterior visual pathway?
• Axons from retinal ganglion cell nuclei → NFL → optic nerves → optic chiasm → optic tract → lateral geniculate nuclei where they synapse
What is cancer-associated retinopathy (CAR) and melanoma-associated retinopathy (MAR)?
• CAR and MAR are paraneoplastic
• Progressive vision loss with photopsias and nyctalopia
• Normal fundus until late in the disease course → attenuated vessels, thinning of RPE, optic nerve atrophy
• Cone and rod dysfunction
• Most common malignancy in CAR: small cell lung cancer, also associated with other lung cancers, breast cancer, endometrial cancer, cervical cancer
What is the definition and causes of palinopsia?
• Persistence or recurrence of images after removal of original stimulus
Causes:
• Most common cause is lesion of parieto-occipital region
• Topiramate, clomiphene, trazodone, hallucinogenic drugs (LSD, mushrooms)
• Migraine
What is the definition and cause of light-near dissociation?
• Pupillary constriction upon near gaze greater than pupillary constriction to light
• Pathophysiology: bilateral loss of afferent input from retina/optic nerves to pupillary light reflex
Causes:
• Argyll-Robertson pupils (disruption of Edinger-Westphal)
• Adie’s tonic pupils (aberrant regeneration of ciliary body parasympathetic input responsible for accomodation)
• Parinaud’s (dorsal midbrain) syndrome (disruption of Edinger-Westphal)
What is the ideal length for a temporal artery biopsy?
• 2 to 3 cm
• Rate of false negative temporal artery biopsy 3-9%
• Obtain contralateral temporal artery biopsy in highly suspicious cases
How does a lesion of the MLF present?
• Causes INO and skew deviation
• Hypertropic eye on the side of lesion
• Ipsilateral INO
How does ocular bobbing present?
• Conjugate fast downward movement of both eyes followed by slow elevation of both eyes back to primary gaze
• Indicates brainstem dysfunction -structural or metabolic
What is hemeralopia?
• Deterioration of vision in higher light environments
• Seen in cone dystrophy
What is the most common mutation in Leber’s hereditary optic neuropathy?
• 11778 mutation LHON