Neuro-Ophthalmology

Question 1

90% of retinal axons terminate where?

Answer 1

the lateral geniculate nucleus, which is the principal sucbcortical structure that carries visual info to the cerebral cortex through the optic radiations

Question 2

Where is the primary visual cortex?

Answer 2

Brodmann’s area 17, or striate cortex

Question 3

Where does the visual information go after the striate cortex, or V1?

Answer 3

the associative visual cortex, areas 18 and 19

Question 4

If visual acuity is decreased, where is the issue typically localized?

Answer 4

either to the eye’s inherent refractive mechanism (and will improve if you test the VA through a pinhole) or to the optic nerve (and will NOT improve through a pinhole)

Question 5

Early optic nerve problems can present with difficulty perceiving which color?

Answer 5

red (a particularly common presentation for MS optic neuritis)

Question 6

How do you test for an afferent pupillary defect (marcus gunn pupil)?

Answer 6

Flash a bright light alternately for 2-3 sec in each eye

if the ipsilateral pupil appears to dilate when the light is directed toward that eye, an afferent pupillary defect is present

Question 7

What visual defect will occur with right optic nerve damage?

Answer 7

right eye blindness

Question 8

What visual defect will occur with chiasm pathology?

Answer 8

bitemporal hemianopsia

Question 9

What visual defect will occur with damage to the right optic tract?

Answer 9

left homonymous hemianopsia

Question 10

What visual defect will occur with damage to the right parietal optic radiation?

Answer 10

left inferior homonymous quandrantonopia

Question 11

What visual defect will occur with damage to the right temporal optic radiation?

Answer 11

left superior homonymous quadrantonopia

Question 12

What visual defect will occur with both optic radiations are damaged?

Answer 12

left homonymous hemianopia (just like with the right optic tract)

Question 13

What visual defect will occur with damage to the right visual cortex?

Answer 13

left homonymous hemianopia with macular sparing

Question 14

What is the technical term for unequal pupil size? In what percentage of people can this be normal?

Answer 14

anisocoria

normal in 25%

Question 15

For the pupillary light reflex, the afferent signal follows the initial visual pathway: retina to optic nerve, chiasm, optic track and then synapses where?

Answer 15

the edinger-westphal nucleus in the rostral aspect of the third nerve nucleus

Question 16

Efferent fibers from the Edinger-Westphal Nucleus then travel with the third cranial nerve. Are these fibers sympathetics or parasympathetics?

Answer 16

parasympathetics

Question 17

These parasympathetic fibers ultimately synapse in what ganglion prior to reaching the pupilloconstrictor?

Answer 17

ciliary ganglion (located in the posterior orbit)

Question 18

The pupillodilator is innervated by sympathetics. Where do these sympathetic fibers start?

Answer 18

in the ipsilateral posterolateral hypothalamus

Question 19

Where do these sympathetic fibers project to?

Answer 19

they descend down the brainstem to the interomediolateral cell column at the C8-T1 spinal level

Question 20

The second order neurons go from C8-T1 to synapse in what ganglion?

Answer 20

superior cervical ganglion

Question 21

The third order sympathetics travel from the superior cervical ganglion to the eye along what structure?

Answer 21

the internal carotid artery into the cavernous sinus

Question 22

What characterizes Horner’s Syndrome?

Answer 22

ipsilateral miosis (small pupil)
ptosis (drooping of upper lid)
inverted ptosis (elevation of the lower lid)

and depending on the level of the lesion…

impaired ipsilateral facial flushing and sweating

Question 23

What effect will cocaine have on the pupil in horner’s syndrome?

Answer 23

cocaine drops will fail to dilate the abnormal pupil (because cocaine inhibits the reuptake of NE from the synaptic cleft, but if the sympathetics aren’t working, this won’t do anything)

Question 24

Cocaine will fail to dilate the pupil, but what will succeed?

Answer 24

apraclonidine (a weak direct-acting alpha1 and alpha2 agonist that dilates the affected eye due to denervation supersensitivity of the iris dilator muscle)

Question 25

What drug will help differentiate between a preganglionic horner syndrome and a postganglionic horner syndrome?

Answer 25

hydroxyamphetamine - the eye will dilate if the damage is in the preganglionic, but won’t with the postganglionic

Question 26

What are the characteristics of a CN III palsy?

Answer 26

ptosis
dilated pupil
opthalmoplegia
(down and out)

Question 27

What will you lose first with optic nerve compression - pupil dilation or eye movement?

Answer 27

you’ll have a dilated pupil, but eye movements will be preserved because the parasympathetics run on the outer edge of the nerve

Question 28

What will you lose first with optic nerve ischemia - pupil dilation or eye movement?

Answer 28

you’ll lose eye movements, but pupil response will be intact because the parasympathetics on the outside have additional blood supply from elsewhere

Question 29

What causes a tonic (Adie’s) pupil?

Answer 29

interruption of the parasympathetic supply from the ciliary ganglion

Question 30

What are the symptoms of a tonic pupil?

Answer 30

anisocoria
photophobia
blurred near vision (bc of some accommodation paresis)
dilated pupil
poor light reaction (with the typical segmental contraction
light-near dissociation

Question 31

Describe an Argyll Robertson pupil

Answer 31

impaired light reaction, but intact light-near dissociation (accommodates, but doesn’t react)

typically associated with syphilis

Question 32

What’s the most common symptom of optic disc swelling?

Answer 32

dimming or blacking out of vision usually lasting a few seconds

usually precipitated by changes in posture or valsalva

Question 33

What are the three most common causes of unilateral optic disc swelling?

Answer 33

optic neuritis
acute ischemic optic neuropathy (AION)
orbital compressive lesions

Question 34

Ipsilateral optic disc atrophy due to compression of the optic nerve by a space-occupying lesion in the frontal lobe with papilledema in the contralateral optic disc due to increased ICP is known as what syndrome?

Answer 34

Foster Kennedy Syndrome

Question 35

What is the difference between comitant strabismus and incomitant strabismus and where is the issue in each?

Answer 35

comitant strabismus occurs when the misalignment is constant in all directions of gaze and each eye has full range of motion (usually an ophthalmologic problem)

incomitant strabismus is when the degree of misalignment varies with the direction of gaze (usually a neurological problem)

Question 36

What is the term for misalignment of the eyes when binocular vision is absent (cover-uncover test)?

Answer 36

phoria (esophoria or exophoria depending on the direction the eye goes)

Question 37

What is the term for misalignment of the eyes when both eyes are opened and binocular vision is possible/

Answer 37

tropia (esotropia or exotropia)

Question 38

What extraoccular muscles are innervated by CN III?

Answer 38

superior rectus
mediccaltus
inferior rectus
levator palpebrae
pupil constrictor
inferior oblique muscles

(all but the lateral rectus and superior oblique)

Question 39

What nerve innervates the superior oblique muscle?

Answer 39

CN IV (which intorts and depresses the adducted eye)

Question 40

A IV nerve palsy will cause what?

Answer 40

oblique diplopia that is worse on down-gaze when the affected eye is adducted (so they usually complain of diplopia when they’re reading or going down stairs)

they will compensate with a lateral head tilt (away from the side of the lesion)

(on exam they’ll have a slightly raised eye when adducted)

Question 41

What does a CN VI nerve palsy cause?

Answer 41

esotropia, especially with ipsilateral gaze (because they can’t abduct)

Question 42

What structures are connected by the MLF?

Answer 42

the contralateral abducens nucleus and paramedian pontine reticular formation with the ipsilateral IIIrd nerve nucleus

so a lesion will cause intranuclear opthalmoplegia (inability to adduct the ipsilateral eye in contralateral gaze, plus nystagmus of the abducting eye)

Question 43

True or false: convergence is preserved in intranuclear opthalmoplegia.

Answer 43

true; convergence does not depend on the MLF

Question 44

What is the differential diagnosis for bilateral intranuclear opthalmoplegias?

Answer 44

Wernicke's encephalopathy
botulism
myasthenia gravis
brainstem strokes
demyelination (MS)

Question 45

Describe “one and a half syndrome”

Answer 45

it occurs as a consequence of a lesion involving the Paramedian pontine reticular formation or the VIth nerve nucleus and the adjacent ipsilateral MLF

you get an ipsilateral gaze palsy and INO on the opposite side (so one and a half) - the only eye movement you get in the lateral plane is abduction of the contralateral eye

Question 46

What region controls vertical eye movements?

Answer 46

the rostral interstitial nucleus of the MLF (riMLF)

Question 47

Where is the rostral interstitial nucleus of the MLF?

Answer 47

in the pretectal midbrain area, near the CN III nucleus

Question 48

Do the fibers controlling upward gaze from the riMLF go to the ipsilateral or contralateral inferior oblique and superior rectus subnuclei?

Answer 48

contralateral

Question 49

What syndrome is characterized by upgaze disturbance, convergence-retraction nystagmus on attempted up-gaze and light-near dissociation?

Answer 49

parinaud’s syndrome

Question 50

What is the typical cause of parinaud’s syndrome?

Answer 50

a pineal tumor compressing the dorsal midbrain

Question 51

Skew deviation is a vertical tropia, generally caused by lesions where?

Answer 51

brainstem or cerebellar