Pupil Flashcards
Where are the three synapses of the pupillary light reflex?
1- pretectal nucleus of midbrain
2- Edinger-Westphal nucleus
3- ciliary ganglion
what is the near triad?
convergence, accommodation, miosis (pinpoint pupil)
What is an APD the hallmark finding of?
APD (afferent pupillary defect) = when eyes do not constrict in response to shining light
-hallmark finding of optic neuropathy
How do you diagnose a Horner’s caused anisocoria?
- mild ptosis
- anisocoria gets worse in the dark (amount of asymmetry of pupils increases)
- dilation lag
- Cocaine test or apraclonidine test
Horner’s due to a 1st order neuron lesion is accompanied by what symptoms?
-unilateral anhidrosis b/c lesion is so proximal (brainstem or spine)
Horner’s due to a 2nd order neuron lesion is accompanied by what symptoms?
-2nd order neuron goes across the lung, down up and around the subclavian artery
=> rare Pancoast tumor in apex of the lung could present w/ Horner’s
-may be accompanied by left armpit numbness
What is the go-to diagnosis for a painful isolated Horner’s syndrome?
Carotid dissection
- 3rd order neuron affected
- painful isolated Horner’s is a carotid dissection until proven otherwise
Segmentation of pupil is a finding of what disorder?
Adie’s tonic pupil
-loss of parasympathetics for light response due to ciliary ganglion lesion
What is the go-to diagnosis for a pupil involving third nerve palsy?
Posterior communicating artery (PCA) aneurysm
What ocular finding could be indicative of carotid dissection?
Painful isolated Horner’s
What ocular finding could be indicative of a PCA aneurysm?
Pupil involving 3rd nerve palsy
-b/c of the anatomy of the subarachnoid space near the cavernous sinus where the third nerve is very close to the posterior communicating artery => PCA aneurysm could compress CN III
Argyll Roberton Pupils
- same as dorsal midbrain syndrome
- pupil’s don’t respond to light (don’t constrict), but have a brisk response to near
Locate the lesion: diplopia is binocular, horizontal, worse at right gaze and at distance
Right 6th nerve palsy
- binocular => neurologic cause
- worse at distance => eyes cannot splay out and down (lateral rectus)
- worse on right gaze => right sided (being using right 6th when looking right not left 6th)
Locate the lesion: diplopia is bipolar, verticla, worse at right gaze and near
Left 4th nerve palsy
-binocular => neurologic cause
-worse near while vertical => activity of opposite superior oblique
(if worse near while horizontal would be medial rectus involved)
Horizontal diplopia worse at distance indicates issues w/ which extraocular muscle?
Lateral rectus (CN VI innervated) => 6th nerve palsy
Horizontal diplopia worse at near indicates issues w/ which extraocular muscle?
Medial rectus (CN III innervated) => 3rd nerve palsy
What muscle moves the right eye up to the right?
Superior rectus (CN III)
What muscle moves the left eye up to the right?
Inferior oblique (CN III) -recall that the inferior oblique muscles are the intorters
Which extraocular muscle fxns to intort the eye?
Inferior oblique
- intort as in clockwise
- moves left eye up and medially (up and right)
- moves right eye up and medially (up and left)
Which extraocular muscle fxns to extort the eye?
Superior oblique
- extort as in counterclockwise
- moves left eye down and laterally
- moves right eye down and laterally (down and right)
Localize a lesion causing oculomotor palsy and optic nerve dysfunction
Orbital apex
-top of the orbit of the eye = where CN II and CN III are together
How may giant cell arteritis present?
As an isolated third nerve paresis
- paresis = weakness, partial paralysis
- giant cell arteritis = inflammatory vasculitis (disease of the BV)
- most dangerous if in opthlamic artery (can => blindness)
What is the result of a lesion of the abducens nucleus?
Right gaze palsy
not a true 6th palsy
What may 6th nerve palsy be a sign of in the head?
High pressure
-b/c 6th nerve pathway: makes a very strict right angle turn in to the cavernous sinus => is at high risk of compression due to high pressure in the subarachnoid space (high pressure or meningitis)
Localize the lesion: 6th nerve palsy + Horner’s syndrome
Cavernous sinus: where CN VI and sympathetics (carotid plexus) run together
Which CNs run through the cavernous sinus?
CN III, IV, VI, V1 and V2
Which CN is the only one that runs freely through the cavernous sinus?
CN VI
Localize the lesion: horizontal binocular diplopia, worse at distance and when look left
Left 6th nerve palsy = abduction deficit
Which cranial nerve has the longest intracranial course?
CN IV
-even crosses the superior medullary velum
What is the most common cause of a IV nerve palsy?
Trauma: 40% caused by trauma
30% unknown or congenital
20% ischemia
10% neoplasm
Localize the lesion: facial sensory loss + optic nerve dysfunction
Cavernous sinus (CN II and V1/V2)
Localize the lesion: optic nerve dysfunction + nerve palsy
Cavernous sinus
Which two causes of vertical diplopia spare the pupil
Both MG (myestina gravis) and thyroid eye disease spare the pupil
-while cranial nerve palsies do not
