Neuro-ophthalmology Flashcards
(200 cards)
1
Q
What is skew deviation?
A
• 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
2
Q
What is the difference between congenital nystagmus and latent nystagmus?
A
• Congenital nystagmus: slow phase velocity accelerates over time
• Latent nystagmus: slow phase velocity either constant velocity or decelerating velocity
3
Q
What was the optic neuritis treatment trial and its findings?
A
• 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
4
Q
Which diseases are associated with vascular compression induced neuropathy by aberrant, ectatic, or dilated intracranial artery compressing on cranial nerve?
A
• Superior oblique myokymia
• Trigeminal neuralgia
• Hemifacial spasm
5
Q
What is superior oblique myokymia?
A
• 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
6
Q
What is trigeminal neuralgia?
A
• 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
7
Q
What is hemifacial spasm?
A
• 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
8
Q
What is benign essential blepharospasm?
A
• 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
9
Q
What is the differential diagnosis for alternating hypertropia?
A
• 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
10
Q
What is Riddoch phenomenon?
A
• In cortical blindness, ability to see moving targets but unable to see any stationary targets
11
Q
What is Anton syndrome?
A
• Patient with cortical blindness that is in denial of their blindness
12
Q
What is Pulfrich phenomenon?
A
● 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
13
Q
What is Charles Bonnet syndrome?
A
• 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
14
Q
What are the most common visual abnormalities associated with optic disc drusen?
A
• Visual field defects (75%-90%): most commonly enlarged blind spot
• Transient visual obscurations (5-10%) due to transient optic disc ischemia
15
Q
What are the ocular findings in Parkinson’s disease?
A
• Apraxia of eyelid opening
• Square wave jerks
• Convergence insufficiency
• Blepharospasm
• Dry eye
• Decreased blink rate
16
Q
What is the ocular effect of progressive supranuclear palsy?
A
• Vertical saccades predominantly
17
Q
What is ocular neuromyotonia?
A
• 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
18
Q
What is autosomal dominant optic atrophy?
A
• 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)
19
Q
What visual field (VF) defects are associated with mild to moderate temporal pallor?
A
• Associated with many different VF defects, including isolated central visual field defects
20
Q
What percentage of the general population has physiologic anisocoria?
A
• Approximately 20%
• Usually <1 mm difference in pupils
• Anisocoria symmetric in light and dark or slightly greater in the dark
21
Q
What work up should be done for optic nerve hypoplasia?
A
• MRI brain
• Endocrine evaluation
22
Q
What are optic nerve drusen?
A
• 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
23
Q
What is the differential diagnosis for optociliary shunt vessels (retinochoroidal collaterals)?
A
• Optic nerve sheath meningioma
• Optic nerve glioma
• Chronic papilledema
• Chronic glaucoma
24
Q
What is the definition of optociliary shunt vessels (retinochoroidal collaterals)?
A
• 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
25
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
26
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
27
What are the most common causes of retrochiasmal visual loss adults and children?
• Adults: stroke (60%), trauma (10%), hemorrhage (10%)
• Children: trauma and tumors
28
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
29
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)
30
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
31
What is sildenafil-related chromatopsia?
• Blue chromatopsia
32
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
33
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
34
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
35
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
36
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)
37
What is DWI MRI?
• Diffusion weighted imaging
• Highlights recent vascular perfusion abnormalities (i.e. recent stroke)
38
What is T1 MRI?
• Best for visualization of anatomy
• Fat is bright
• CSF, vitreous, and air are dark
39
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
40
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
41
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
42
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
43
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
44
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
45
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
46
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
47
How does one test ocular ductions?
• Test ocular motility under monocular conditions
48
How does one test ocular versions?
• Test ocular motility under binocular conditions
49
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
50
What hormone is most commonly deficient in septo-optic dysplasia?
• Growth hormone
51
What are the causes of infiltrative optic neuropathy?
• Optic nerve gliomas
• Leukemia
• Lymphoma
• Sarcoidosis
• Syphilis
• TB
• Fungal
• Meningeal-carcinomatosis
52
What is ocular dysmetria?
• Overshoot or undershoot of eyes upon refixation to new target
• Suggestive of cerebellar pathology
53
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
54
What is Wolfram syndrome?
• Autosomal recessive or sporadic
• Diabetes insipidus plus diabetes mellitus plus optic atrophy plus sensorineural deafness
55
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
56
What is the most accurate means of quantifying afferent pupillary defect?
• Neutral density filters
57
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)
58
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
59
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)
60
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
61
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
62
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
63
What is Weber syndrome?
• Midbrain lesion affecting cranial nerve 3 and cerebral peduncle
• Cranial nerve 3 palsy
• Contralateral hemiparesis
64
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)
65
What is Claude syndrome?
• Damage to dorsal midbrain
• Affecting superior cerebellar peduncle and cranial nerve 3
• Cranial nerve 3 palsy and contralateral ataxia
66
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
67
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)
68
What is Sherrington's law?
• Monocular principle
• Increased contraction of the innervated muscle results in equal relaxation the antagonist muscles
69
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
70
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
71
What is the differential diagnosis for the combination of uveitis and facial nerve palsy?
• Lyme disease
• Sarcoidosis
72
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
73
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
74
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
75
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)
76
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
77
How does a lesion of the MLF present?
• Causes INO and skew deviation
• Hypertropic eye on the side of lesion
• Ipsilateral INO
78
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
79
What is hemeralopia?
• Deterioration of vision in higher light environments
• Seen in cone dystrophy
80
What is the most common mutation in Leber's hereditary optic neuropathy?
• 11778 mutation LHON
81
What mutation is most likely to show spontaneous late visual recovery in Leber's hereditary optic neuropathy?
• 14484 mutation LHON
82
What size is the smallest aneurysm detectable by MRA/CTA?
• 3 mm
• Gold standard for cerebral aneurysm detection is catheter angiography
83
What features of acute optic disc edema distinguish elevated intracranial pressure from other causes?
• Papilledema → bilateral optic disc swelling, retain good visual function (i.e. good visual acuity, central visual field, color vision)
• Optic disc edema from other causes → prominent visual field and/or visual function deficits early in the disease
84
How many central degrees of visual field does amsler grid testing evaluate?
• Central 20 degrees (10 degrees on either side of fixation)
85
What are the various types of humphrey visual field testing and the degrees they assess?
• 10-2: central 20 degrees
• 24-2: 48 degrees vertical, 54 degrees horizontal
• 30-2: 60 degrees
86
What is the differential diagnosis for optic disc edema?
• Most common: papilledema, optic neuritis, AION, pseudopapilledema
• Somewhat common: CRVO, diabetic papillopathy
• Less common: posterior uveitis, hypotony, malignant hypertension, Leber's hereditary optic neuropathy, optic nerve infiltration (i.e. sarcoidosis, lymphoma)
87
What visual field defects are expected to result from a pituitary mass?
• Bilateral mostly supratemporal defects that respect vertical midline→ extend to complete bitemporal hemianopia late in disease
• Exception to this → craniopharyngioma which arises from above chiasm and compresses superior aspect of chiasm → bitemporal defects greater inferiorly
88
What is Gradenigos syndrome?
• Inflammation of petrous portion of temporal bone
• Affects cranial nerves 5, 6, and 7
• Severe ipsilateral trigeminal pain and cranial nerve 6 and 7 palsy
89
What is the blood supply to lateral medulla?
• Posterior inferior cerebellar artery
90
What is the cause of binocular diplopia after cataract surgery?
• Rare
• Seen with retrobulbar injection → mechanical needle trauma to inferior rectus → hemorrhage or nerve damage to inferior rectus
• May resolve over time or may cause chronic fibrosis of inferior rectus
91
In optic neuritis, what is the appearance of the optic nerve and how does it correlate with the risk of developing MS?
• Based on optic neuritis treatment trial
• Severe optic disc edema with peripapillary retinal hemorrhage inversely related to risk of MS development
• Patients with peripapillary hemorrhage and normal MRI → none developed MS at 10 year mark
• All patients with optic neuritis and normal brain MRI → 20% chance of MS by 10 years
• Patients with optic neuritis and massive disc edema or heme → usually have other etiologies for optic nerve dysfunction
92
What is the best test to distinguish between AION and NAION?
• Fluorescein angiography → patchy choroidal perfusion with AION → commonly secondary to GCA → infarct posterior ciliary artery → presents as vision loss with normal fundus exam
93
What is the role of apraclonidine in Horner's syndrome?
• Apraclonidine is a alpha-adrenergic receptor agonist, has more of an effect on alpha-2 receptors than alpha-1 receptors
• Horner’s syndrome has up-regulation of post-synaptic alpha-1 receptors (usually after 2-5 days of injury)
• Normal pupil has no reaction to apraclonidine
• Horner’s pupil dilates to apraclonidine due to upregulation of alpha-1 receptor
94
What is the cause of benign episodic pupillary mydriasis?
Migraine headache
95
What is Brown syndrome?
• Inability to elevate the eye when adducted
• Unilateral or bilateral
• Type of restrictive strabismus
• Cause of congenital Brown syndrome: due to short superior oblique tendon
• Causes of acquired Brown syndrome: trauma, inflammation from idiopathic orbital inflammation, rheumatoid arthritis, Sjogren's syndrome, neoplasm
96
What is Tolosa Hunt syndrome?
• Idiopathic sterile inflammation of cavernous sinus
• Severe ipsilateral periorbital pain along with deficits of any of the nerves passing through the cavernous sinus (cranial nerve 3, 4, V1, V2, 6, sympathetics)
• Diagnosis of exclusion→ first rule out infection, lymphoma, cancer
97
What is Miller Fisher syndrome?
● Oculomotor predominant variant of Guillain-Barre syndrome (GBS)
● Affects eye movements first→ progresses to systemic motor and sensory neuropathy typical of GBS
● Tetrad of Miller-Fisher
○ Facial diplegia
○ Ophthalmoplegia
○ Ataxia
○ Areflexia
98
What is Heimann-Bielschowsky phenomenon?
• Monocular vertical pendular nystagmus that occurs in poorly seeing eyes (often in children)
• Can occur after vision loss from optic nerve gliomas, amblyopia, trauma, or other causes of vision loss
• Any child with monocular nystagmus → neuroimage if cause of vision loss is unknown
99
What is the duration of vision loss in the following conditions: migraine aura, amaurosis fugax,transient visual obscurations (TVO)?
• Migraine aura: 10-60 minutes
• Amaurosis fugax: 1-10 minutes
• TVO: few seconds
100
What are the clinical findings and cause of a lesion to the central tegmental tract?
● Central tegmental tract runs from inferior olivary nucleus in the medulla to the red nucleus in the midbrain
● Results in oculopalatal myoclonus
○ Bilateral acquired, vertical and pendular nystagmus
○ Rhythmic movements of face, soft palate, pharynx, tongue, larynx, diaphragm, extremities
● Caused by brain stem stroke
101
What is Marcus Gunn jaw-winking syndrome?
• Aberrant innervation connection (synkinesis) between muscles of (pterygoid) and levator muscle
• Congenital
• Autosomal dominant
• Variant of congenital ptosis with fibrosis
Types:
1.
Aberrant connection between EXTERNAL pterygoid and levator palpebrae superioris → ptotic eyelid elevated with opening of mouth, or movement of jaw to contralateral side, or jaw protrusion
2.
Aberrant connection between INTERNAL pterygoid and levator palpebrae superioris → ptotic eyelid elevated with closure of mouth
102
What is the normal levator function (LF)?
• More than 12-16 mm
• LF < 12 mm → myopathic or neurogenic cause of ptosis
103
What is the definition and causes of paradoxical pupillary reaction?
• Immediate pupillary constriction instead of dilation upon turning exam room lights off
• Highly suggestive of optic nerve or retinal pathology
• Also seen with children with poor vision
Differential diagnosis
• Congenital stationary night blindness
• Congenital achromatopsia
• Best disease
• Dominant optic atrophy
104
What work up should be done for neuroretinitis?
• Serology work up: bartonella henselae, syphilis, sarcoidosis, toxoplasmosis, lyme
• If serologic workup negative → idiopathic neuroretinitis AKA Leber’s idiopathic stellate neuroretinitis
• Neuro-imaging is not necessary
105
What is the most specific sign for optic neuritis?
• Eye pain, worse with eye movement
• Present in 92% of patients with optic neuritis, per optic neuritis treatment trial
106
In thyroid-associated ophthalmopathy, what is the threshold of difference in IOP in primary gaze and upgaze to be considered significant?
5 mm Hg higher in upgaze
107
What is Balint syndrome?
• Bilateral dorsal parieto-occipital lesions
• Difficult with visuospatial tasks and visual processing
Classic triad:
1.
Optic ataxia (poor hand eye coordination)
2.
Ocular motor apraxia (difficulty initiating saccades)
3.
Simultagnosia (failure to understand entire meaning of picture despite retaining ability to recognize isolated objects within picture) -most prevalent
108
What is periodic alternating nystagmus (AKA central vestibular instability nystagmus)?
• Bilateral horizontal jerk nystagmus that periodically changes direction (usually 2-4 minutes)
• Potentially alternating head turn
• Null point alternates
• Etiology: posterior fossa pathology in brainstem or cerebellum
• Any surgery that would shift null point to primary gaze should be avoided
109
What is spasmus nutans?
• Benign, self limited
• High frequency, low amplitude nystagmus
• Dysconjugate
• Associated torticollis and head nodding
• Usually horizontal and bilateral; can be unilateral, vertical or rotary
• Presents within first 2 years of life and resolves within 1-2 years
• Resembles Heimann-Bielschowsky
• Obtain neuroimaging to rule out anterior optic pathway glioma
110
What is eight-and-a-half syndrome?
• One-and-a-half syndrome (internuclear ophthalmoplegia with ipsilateral horizontal gaze palsy) plus ipsilateral facial palsy
111
How is chronic progressive external ophthalmoplegia diagnosed?
• Skeletal muscle biopsy
• Biopsy positive for high number of cytochrome C oxidase negative fibers with ragged red fibers on Gomori’s trichrome stain
112
What are the clinical findings in Holmes-Adies syndrome?
• Adie tonic pupil plus decreased deep tendon reflexes (hyporeflexia)
113
What is the etiology and clinical findings in acute optic disc edema?
• Caused by impaired axoplasmic flow in ganglion cell axons
Clinical findings
• Elevated appearance of optic nerve head
• Blurring of optic nerve head margins and blood vessels as they traverse border of optic nerve
• Peripapillary retinal venous dilation and tortuosity
• Peripapillary hemorrhages and exudates
• Hyperemic vasculature of optic nerve head
• Chorioretinal folds
• Macular edema
114
Ishihara color plates test what type of color vision deficiency?
Red-green deficiency
115
Lanthony tritan plates test which type of color vision deficiency?
Blue-yellow deficiency
116
What is the 10-20-40-60 rule?
• Obtained from optic neuritis treatment trial
• Isolated optic neuritis, negative MRI: 22%risk of MS development in 10years
• All patients with single bout of clinically isolated optic neuritis (not taking into account MRI findings): 38% risk of MS development in 10 years
• Optic neuritis plus one or more white matter lesions on MRI: 56% risk of MS development in 10years
117
What structures sit in the sella turcica and above the sella turcica?
• Pituitary gland sits inside sella turcica
• Optic chiasm is approximately 10 mm superiorly
118
What bone makes up the sella turcica?
Sphenoid bone
119
What are the similarities and differences between Pseudo Foster Kennedy (PFK) syndrome and Foster Kennedy syndrome (FK)?
Common among both PFK and FK
• One side with atrophic optic nerve and another side with swollen optic nerve
Differences between PFK and FK
• PFK:bilateral sequential attacks of NAION. First optic nerve affected becomes pale 4-8 weeks after attack, then second optic nerve becomes affected and acutely swollen. 5-year risk of involvement of fellow eye with NAION is approximately 15%
• FK: intracranial mass on one side compressing ipsilateral optic nerve causing optic atrophy and thus optic nerve pallor. While also raising intracranial pressure and causing contralateral optic disc to swelling
120
What are the clinical findings in Heerfordt syndrome (uveoparotid fever)?
• Uveitis
• Facial palsy due to parotid gland swelling
• Fever
• Seen in sarcoidosis
121
What are the clinical findings in Lofgren syndrome?
• Erythema nodosum
• Bilateral hilar adenopathy
• Arthritis
• Seen in sarcoidosis
122
Where is the lesion in Millard-Gabler syndrome localized and what are the clinical findings?
• Lesion located in ventral pons affecting cranial nerve 6, 7 and corticospinal tract
• Ipsilateral abduction deficit
• Contralateral spastic hemiplegia
• Ipsilateral facial weakness
123
What is the indication for use of fingolimod?
• Treat relapsing remitting multiple sclerosis
124
What is the cause of gaze-evoked amaurosis?
• Intermittent occlusion of retinal or optic nerve vasculature caused by intermittent compression from orbital mass when eye is turning in a certain position
• Most common gaze is downgaze
125
What is dissociated nystagmus?
• Amplitude of wave form of nystagmus differs in each eye (nystagmus more pronounced in one eye than the other eye)
126
What is disconjugate nystagmus?
• AKA disjunctive nystagmus
• Direction of nystagmus differs between eyes (i.e. right beating nystagmus OD; left beating nystagmus OS)
127
What is the null point of nystagmus?
• Point of gaze where nystagmus is least severe
128
How is photostress recovery time measured and which two pathologies does it distinguish?
• Measure BCVA, then shine bright light into undilated pupil for 10 seconds. Then measure the time required to read BCVA line or one line larger
• > 90 seconds indicates significant maculopathy
• Distinguishes photoreceptor dysfunction related maculopathy from optic neuropathy
129
Which neurological disorders are associated with irregularly shaped pupils?
• Midbrain corectopia: diffuse damage to midbrain, selective inhibition of pupillomotor fibers from Edinger-Westphal nucleus
• Migraine associated: "tadpole pupils" occurs in one eye, sectoral dilation or spasm of pupil lasting few minutes
130
According to the ischemic optic neuropathy decompression trial follow up study, what was the rate of contralateral involvement after five years in patients with unilateral NAION?
14.7% in 5 years
131
What is the rate of contralateral involvement in untreated monocular vision loss from arteritic anterior ischemic optic neuropathy (GCA)?
54-95% within weeks
132
Which drugs can cause drug-induced intracranial hypertension?
• Vitamin A and derivatives (i.e. isotretinoin)
• Tetracyclines
• Cyclosporine
• Oral contraceptives
• Prednisone, especially with sudden withdrawal
• Synthetic growth hormone
133
What are the causes of superior ophthalmic vein dilation?
• High flow carotid cavernous fistulas
• Low flow dural sinus fistulas
• Cavernous sinus thrombosis
134
What is rebound nystagmus?
• Occurs seconds after eyes brought to primary gaze following prolonged eccentric gaze
• Fast phase nystagmus opposite to the previous gaze direction
135
What is gaze evoked nystagmus?
• Inability to maintain fixation in eccentric gaze
• Eyes drift back to midline and corrective saccade is generated to reposition eyes in eccentric target
• Fast phase is always direction of eccentric gaze
136
What are the findings and associations with segmental optic nerve hypoplasia?
● Usually superior half of the optic disc is hypoplastic
● Papillomacular bundle spared
● Normal visual acuity and color vision
● Associations:
○ Maternal diabetes during pregnancy
○ Isolated finding
137
What is a tonic pupil?
• Females 70%
• Unilateral 80%
• Majority are idiopathic and isolated
• Disruption of post-ganglionic parasympathetic pupillomotor fibers from ciliary ganglion
• Hypersensitive to parasympathomimetic
• Light near dissociation, segmental constriction, hypersensitivity to dilute pilocarpine 0.125%, loss of accommodation
• Anisocoria greater in light
• Associations: neurosyphilis, diabetes, chronic alcoholism, dysautonomia
138
What is the most common location of aneurysm causing pupil-involving cranial nerve 3 palsy?
Junction of posterior communicating artery and internal carotid artery
139
What diseases are associated with agenesis of one or more cranial nerve nuclei in the brainstem?
• Congenital fibrosis of extraocular muscles: congenital agenesis of cranial nerve 3, levator subnuclei and bilateral superior rectus subnuclei
• Duane syndrome: agenesis or dysgenesis of cranial nerve 6 and nucleus
• Mobius syndrome: agenesis of 6th and 7th cranial nerve
140
What is the cardinal feature of internuclear ophthalmoplegia?
Slow adduction on the affected side compared to abduction velocity of contralateral eye
141
What is ophthalmoplegic migraine?
• Episodic, localized orbital pain or headache associated with partial or complete paralysis of cranial nerve 3
• This is rare cause of episodic cranial nerve 3 palsy
• Most common in childhood
142
What is the Goldmann perimetry nomenclature for target size, intensity, and filter?
Target size presented with roman a number: 0 to V
• 0: 1/16 mm2
• I: 1/4 mm2
• II: 1 mm2
• III: 4 mm2
• IV: 16 mm2
• V: 64 mm2
Brightness presented with an arabic number: 1 to 4
• 1: least intense
• 4: most intense
Filter presented by alphabets: A to E
• E is the most commonly used filter
V4e = largest and brightest target
143
What are the various presentations of giant cell arteritis?
• Anterior ischemic optic neuropathy
• Posterior ischemic optic neuropathy
• Central retinal artery occlusion
• Branch retinal artery occlusion
• Choroidal infarction
• Ocular ischemia
• CNS stroke
• Diplopia secondary ischemia of extraocular muscles or ocular motor nerves
• Vasculitis of elastin containing large and medium sized arteries of head and neck
144
What are the clinical findings in Leber’s hereditary optic neuropathy?
• Optic disc swelling without leakage on fluorescein angiogram
• Peripapillary telangiectasia
• Thickening of peripapillary retina
• Tortuosity of medium sized retinal arterioles
• Cecocentral visual field defect
• Fellow eye with similar progress over weeks to months
145
What is the treatment for Leber’s hereditary optic neuropathy?
• No treatment
• Avoiding smoking and excess alcohol use is prudent to decreasing oxidative demand
146
What is numb-chin syndrome?
• AKA mental nerve neuropathy
• Highly concerning for malignancy
• Most common associated malignancies: lymphoma and metastatic breast cancer
• Sarcoidosis also been described as cause of mental nerve neuropathy
147
What is the standard "cycle" for periodic alternating nystagmus?
• Duration: 2-4 minutes
• One cycle: from static phase through 2 nystagmus phases in different directions and back to static phase
148
What conditions are associated with small optic disc drusen?
• Retinitis pigmentosa
• Pseudoxanthoma elasticum
• Caucasian race
149
Which secreting pituitary adenoma is most likely to present with optic chiasm compression?
Prolactin secreting adenoma
150
What are the best tests for posterior cortical atrophy?
• Functional MRI
• PET scan SPECT → test highlights hypometabolism and hypoperfusion in the brain
151
What is the differential diagnosis, etiology, and workup for nystagmus-like eye movements without intersaccadic interval?
Ocular flutter
• Repetitive purely horizontal saccades
• Bursts of small-amplitude
• Very high frequency (10-15 Hx)
Opsoclonus (saccadomania)
• Dramatic bilateral eye movements -high frequency with larger amplitude
• Involuntary multidirectional saccades
Etiology of ocular flutter and opsoclonus
• May relate to dysfunction of omnipause neurons of pons or to connections with these cells
Workup
• Rule out paraneoplastic etiology. Children → most commonly secondary to neuroblastoma. Adults → most commonly secondary to small cell carcinoma of lung, breast cancer or ovarian cancer
• In young adults, evaluate for multiple sclerosis
152
Which extraocular muscles are innervated by the right cranial nerve 3 nucleus?
• Right inferior oblique, right inferior rectus, right medial rectus, LEFT superior rectus
• Fibers innervating superior rectus muscle decussate and supply contralateral eye. The decussating fibers pass through the opposite superior rectus nucleus thus damage to right cranial nerve 3 nuclear result in bilateral superior rectus muscle involvement
153
Which extraocular muscles are innervated by the right cranial nerve 4 nucleus?
• Left superior oblique, only cranial nerve to exit dorsal aspect of brainstem and decussates before exiting
154
What is the innervation of the levator palpebrae superioris muscle?
• Muscles on both sides are innervated by centrally located common 3rd nerve subnucleus
155
Which extraocular muscles would be affected by a lesion of the 3rd nerve nucleus?
• Ipsilateral palsy of inferior rectus, inferior oblique, medial rectus, superior rectus, levator palpebrae superioris
• Contralateral palsy of superior rectus and levator palpebrae superioris
156
What kind of nystagmus is associated with hypertrophy of inferior olivary nucleus in the medulla on MRI?
Oculopalatal myoclonus related pendular nystagmus
157
How does one conduct visually evoked potentials and what is their utility?
• Rarely useful clinically
• Present visual stimulus to one eye, then measure electrical brain waves over occipital cortex → rough estimate of function of entire afferent visual pathway
• Good for estimating visual function in patients unable to communicate
• Pattern-reversal VEP are useful for estimating actual visual acuity and require good cooperation
158
What are the indications for surgical intervention in idiopathic intracranial hypertension?
• Progressive visual loss: optic nerve sheath fenestration → scar quickly, 15% success rate at 6 years
• Intractable headaches despite maximal medical therapy → VP shunts → successful in relieving headache but high complication rate. Revisions in approximately 50%
159
What is pituitary apoplexy?
• AKA hemorrhage into pituitary gland
Cause of hemorrhage
• Pituitary adenoma
• Enlarged necrotic pituitary in peripartum period, known as Sheehan syndrome
• MRI brain is the study of choice
160
What is the rate of morbidity of catheter angiography?
1% to 2.5% due to risk of ischemia from emboli and vasospasm
161
What is oculomasticatory myorhythmia?
• Very rare
• Eye and facial movements seen in Whipple disease with CNS involvement
• Use of muscles of mastication causes ocular oscillation
• Vertical saccadic deficiencies
• Chronic disease due to duodenal infestation with tropheryma whippeli
• Associated with unintentional weight loss, fevers, lymphadenopathy
162
What is the definition of elevated opening lumbar puncture pressure?
> 25 cmH2O
163
What is volitional nystagmus?
• Voluntary nystagmus
• Capable by 8% of popular
• Bilateral
• Conjugate
• High frequency, low amplitude
• Usually horizontal, can be vertical
164
What is Melkersson Rosenthal syndrome?
• Triad: recurrent unilateral or bilateral facial paralysis (30%); chronic orofacial edema (usually lips); lingua plicata (fissured tongue, image below)
• Cause unknown and no well defined treatment
• Diagnose with lip biopsy → granulomatous infiltration
165
Which bone makes up the optic canal?
Lesser wing of sphenoid
166
What are the contents of the optic canal?
• Optic nerve
• Ophthalmic artery
• Sympathetic nerve
167
What are the clinical findings and work up for ocular ischemic syndrome?
● Light induced amaurosis -characteristic
● Orbital or periocular pain that improves with laying down
● Hypotony
● Corneal edema
● Anterior chamber flare
● Mid-peripheral dot blot hemorrhage in the retina
● Retinal neovascularization
● Work up:
○ Fluorescein angiogram (delayed arm to eye time; areas of retinal, optic nerve neovascularization)
○ Carotid dopplers (stenosis)
○ CTA/MRA
168
What percentage of microvascular or vasculopathic cranial nerve 3 palsies demonstrate some degree of pupil involvement?
0.2
169
How long after initiating steroid treatment can temporal artery biopsy be delayed in cases of giant cell arteritis before compromising diagnostic yield?
1 to 2 weeks
170
How many ganglion cell axons combine to form the optic nerve?
1.2 million
171
What are the features of congenital nystagmus?
"CONGENITAL"
Convergence and eye closure dampen nystagmus
Oscillopsia absent
Null zone present
Gaze position does not change direction of nystagmus
Equal amplitude and frequency in each eye
Near acuity is good because convergence dampens nystagmus
Inversion of optokinetic nystagmus
Turning of head or abnormal head posture to allow eyes to enter null zone leads to better visual acuity
Absent nystagmus during sleep
Latent nystagmus occurs
172
Macular sparing homonymous hemianopia is specific to lesion in which cerebral lobe and most likely caused by stroke of which artery?
● Occipital lobe
● Posterior cerebral artery
○ Posterior cerebral artery supplies majority of primary visual cortex
○ Middle cerebral artery supplies very posterior tip of primary visual cortex of occipital lobe responsible for contralateral macular portion of hemifield
173
What are the most common symptoms of idiopathic intracranial hypertension (IIH) and most common visual field defects in IIH based on the IIH treatment trial?
● Symptoms:
○ Headache (most common; 84%)
○ Transient visual obscurations
○ Pulse tinnitus
○ Back pain
○ Diplopia
● Visual field defects:
○ Partial arcuate defects with and without enlarged blind spot (70-80%)
○ Enlarged blind spot alone
174
What is Ramsay Hunt syndrome?
Herpes zoster involving cranial nerve 7
175
What is Foville syndrome?
• Lesion of dorsal pons
• Ipsilateral cranial nerve 5, 6, and 7 palsy without body weakness
176
What is dorsal midbrain syndrome?
• Compression of posterior midbrain
• Paralysis of upward gaze
• Convergence retraction nystagmus
• Involuntary convergence
• Light near dissociation
• Positive Collier sign -bilateral lid retraction
• Increase in square wave jerks
177
What is sagging eye syndrome?
• Seen in older patients
• Lateral rectus-superior rectus band degenerates with inferior displacement of lateral rectus muscle
• Prolapse of connective tissue supratemporally
• Mild to moderate angle esotropia due to divergence insufficiency
• Normal lateral gaze
• Limited supraduction
• Deep superior sulci
• High lid creases
• Ptosis secondary to levator aponeurosis dehiscence
178
What are the clinical findings in Susac syndrome?
• Hearing loss
• “Boxcar” retinal segmentation of retinal arteries
• Corpus callosum with “snowball lesions” -signs of microinfarcts
• Leptomeningeal enhancement
179
What are some multiple sclerosis medications and their side effects?
• Natalizumab: altered mental status, hemianopia visual field defect due to progressive multifocal leukoencephalopathy in patients who are JC virus positive; nausea, infection, liver dysfunction
• Fingolimod: macular edema
• Interferon: flu-like symptoms, liver function tests changes, bone marrow suppression, thyroid dysfunction
• Glatiramer: skin irritation, skin lipoatrophy, panic attack-like events
180
What are the types of glial cells and their function?
• Types: oligodendrocytes, astrocytes, microglial cells, muller cells
• Overall function: support function of CNS. Proliferate in response to retinal trauma
• Oligodendrocytes → maintain myelin
• Astrocytes → support and nutrition
• Microglial cell (histiocytes of CNS) → phagocytic function
• Muller cells: footplates form inner limiting membrane. Attachment between photoreceptors and Muller cells creates external limiting membrane
181
What is measured with multifocal ERG?
• Direct measure of macular function and central retinal cone-system function
• More objective index of macular function than pattern ERG
182
What is measured with pattern ERG?
• Measure of central retinal ganglion cell function
• Less objective index of macular function than multifocal ERG
183
What is measured with electrooculogram (EOG)?
• Assess health of RPE by measuring changes in corneo-retinal standing potential during light adaptation
• Arden ratio: ratio of light peak (Lp) to dark trough (Dt); determines the normalcy of the results
• Arden ratio 1.80 or greater is normal, 1.65 to 1.80 is abnormal, and < 1.65 is significantly abnormal
184
What is the anatomy of cranial nerve 6?
• Starts at nucleus of dorsal pons → ascends along clivus → crosses petrous apex → passes below petroclinoid ligament → center cavernous sinus
• Takes 90 degree turn over tip of clivus and under petroclinoid ligament → vulnerable to compression from high or low intracranial pressure
185
What is prosopagnosia?
• Inability to recognize familiar faces
• Congenital or acquired from stroke in bilateral inferior occipitotemporal lobes or right inferior occipital lobe
186
Damage to which structure leads to alexia without agraphia (cannot read but can write)?
Selenium of corpus callosum and left occipital lobe
187
What are the clinical findings and cause of lateral medullary syndrome?
• Although lateral medulla is supplied by posterior inferior cerebellar artery, this syndrome is secondary to occlusion of vertebral artery
• Ipsilateral Horner syndrome
• Ipsilateral impairment of pain and temperature sensation over face (descending tract of cranial nerve 5)
• Contralateral impairment of pain and temperature sensation (spinothalamic tract) of body
• Ipsilateral cerebellar ataxia (spinocerebellar tract)
• Ocular tilt reaction (head told toward side of lesion)
• No extremity weakness
• Lateropulsion (sensation of being pulled toward the side of lesion)
• Dysarthria, dysphagia, vertigo
188
What VEP abnormality is present in optic nerve disease?
• Peak-time delay in pattern reversal VEP
• Increased latency in demyelination
189
What VEP abnormality is present in NAION?
Amplitude reduction
190
What VEP abnormality is present in macular dysfunction?
Delayed pattern reversal VEP
191
What is STIR MRI?
• T1 images without confounding bright fat single
• Useful for orbital and spinal cord evaluation
192
What is Uhthoff phenomenon?
Worsening vision in multiple sclerosis patients when their bodies become overheated
193
What are the clinical findings in true infantile nystagmus (AKA congenital motor nystagmus)?
• Paradoxical inversion of OKN response → right jerk nystagmus views OKN to the left, intensity of right jerk nystagmus increases
• Velocity of slow-phase movement increases exponentially with distance and fixation
• X-linked mutations in FERM domain-containing-7 gene
194
What does nystagmus that changes direction with change in fixation indicate?
Fusion maldevelopment nystagmus syndrome (infantile-onset nystagmus) → left jerk nystagmus when right eye is occluded, right jerk nystagmus when left eye is occluded
195
Inferior rectus weakness is most evident in which position?
Abducted position
196
Superior oblique weakness is most evident in which position?
Adducted position
197
Which supranuclear ocular motor lesions produce strabismus and diplopia?
• Convergence insufficiency or spasm
• Divergence insufficiency
• Ocular tilt reaction
• Skew/alternating skew deviation
• Thalamic esodeviation
198
What is the pathway of the pupillary light reflex?
Retina → pretectal nuclei → Edinger-Westphal nuclei → cililary ganglion → pupilloconstrictor fibers
199
What is the optic nerve sheath meningioma triad?
• Painless, slowly progressive vision loss
• Optic atrophy
• Optociliary shunt vessels
200
What is the path of sympathetic fibers in the cavernous sinus?
Within cavernous sinus, fibers leave the carotid in junction with cranial nerve 6 for a few millimeters. Anteriorly in the cavernous sinus, fibers join nasociliary branch of cranial nerve V1.
