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SS - Exam 3 > Neuro-ophtho > Flashcards

Neuro-ophtho Flashcards

1
Q

CN II

A

Optic nerve
Exits at optic foramen
Axons of retinal ganglion cell
Function - carry electrical signal from retina to brain

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2
Q

CN III, IV, VI

A

All exit at orbital fissure
Function - Innervation of Extraocular muscles
III - Oculomotor
IV - trochlear
VI - abducens

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3
Q

CN III

A

Innervates the DR, MR, VR, VO and levator palpebral superioris
– Helps you look up, toward the nose, down & centralize pupil by counteracting the dorsal oblique
- lifts upper lid
PSN Innervation to Iris sphincter muscle and ciliary body (miosis)

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4
Q

Lesion to III causes what strabismus s

A

Down and out strabismus

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5
Q

CN IV

A

Innervates dorsal oblique muscle - helps centralize pupil in counteracting the ventral oblique muscle

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6
Q

Trochlear nerve lesion causes what kind of strabismus

A

Inward/cross eyed strabismus

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7
Q

CN VI

A

Innervates lateral rectus and retractor bulbi
Moves laterally, sucks eye inward = moving 3rd eye lid

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8
Q

Abducens nerve lesion leads to what kind of strabismus

A

Unilateral medial strabismus

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9
Q

Remember 3

A

DO4LRRB6Rest3
Dorsal oblique - CN 4
Lateral recuts & retractor bulbi - CN 6
Rest of the muscles - CN 3

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10
Q

CN V

A

Ophthalmic branch exits orbital fissure
Maxillary branch exits round foramen via rostral alar canal
Mandibular branch exits oval foramen

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11
Q

CN V innervation

A

Ophthalmic brachial provides sensory to the orbit, medial canthus, conjunctiva and cornea
Maxillary branch provides sensory to lateral canthus
Mandibular provides to muscles of mastication

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12
Q

CN VII

A

Exits stylomastoid foramen
Function - innervation to orbicularis oculi = blinking
PNS Innervation to lacrimal gland & 3rd eyelid gland

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13
Q

VIII

A

Exits internal acoustic meatus
Functions to coordinate eye movement with head movement so vision isn’t blurry
Works with the medial longitudinal Faciculus

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14
Q

CN X

A

PSN tone in decreasing heart rate - pressing on eyelids*
Beneficial for vagal maneuvers
Can be detrimental - oculocardiac reflex

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15
Q

Parasympathetic input on CN III

A

Parasympathetic nucleus of CN III, aka Edinger-Westphal nucleus
• Innervation to iris sphincter muscle and ciliary muscles
• Functions: miosis and accommodation

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16
Q

Parasympathetic input for CN VII

A

Parasympathetic nucleus of CN VII
Innervation to lacrimal /3rd eyelid glands
Functions: lacrimation & nasal wetting
neurogenic KCS: dry eye
Stimulation a Parasympathomimetics - pilocarpine
Inhibition w parasymatholytics/anticholinergic - atropine, glycopyrrolate

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17
Q

Xeromycteria

A

Commonly occurs with neurogenic KCS
Dry eyes and dry nose

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18
Q

Testing vision

A

Menace response
Cotton ball test

19
Q

Menace response

A

Afferent info - CN II
Efferent info - CN VII = blinking & CN VI = globe retraction
Not a reflex, its a learned response. Will be absent in young puppies/animals (<12 wks)

20
Q

cotton ball test

A

Evaluates CN II (afferent)
Tracking moving object w eyes

21
Q

Inconsistencies in results

A

Age - learned response vs reflex
Stoic animals
Pain (ocular or systemic)
Cats - wont menace
Exotics - birds/reptiles

22
Q

Testing sensation

A

Palpebral reflex - blinking in response to touch,
A info - CN V opthalmic branch/max branch
E info - CN VII
Corneal reflex - blinking in response to touch on cornea
A info - CN V ophthalmic branch
E info - CN VII (blink) and CN VI (globe retraction)

23
Q

Testing movement

A

Oculocephlic reflex - dolls eye reflex, moving head to Track movement
Afferent info - CN VII
Efferent info - CN III, IV, VI

24
Q

Dazzle reflex

A

Stimulated with bright light = blink and globe retraction
Afferent - CN II
Efferent - CN VII and CN VI
It’s a pain reflex due to bright light, its pre-cortical and does not signify vision

25
Q

Visual pathway

A

Nasal and lateral hemiretinas - optic nerve - cross over at optic chiasm - optic tract = Lateral geniculate nucleus = visual cortex

26
Q

PLR

A

Afferent - CN II
Nasal & lateral hemiretinas - optic nerve - optic chiasm X - optic tract - retractable nucleus —> 2nd cross over
50% of fibers cross to ipsilateral side

27
Q

PLR efferent

A

efferent CN III
Parasympathetic nucleus of CN III (edinger-Westphal nucleus) —> CN III efferent tract —> ciliary ganglion —> Irish sphincter muscle

28
Q

Vision vs PLR

A

Vision
Requires function of millions of photoreceptors
Cortical input and process aka higher centers in brain

29
Q

Vision vs PLR*

A

Doesn’t requires many functional receptors
PLR
Parasympathetic tone
Pretectal nucleus
Precortical response
Reflexes dont see the higher centers of the brain aka reflexes don’t signify vision
However this tract has a double cross over at axons and its not 50:50 in domestic species

30
Q

Direct response

A

Direct is an ipsilateral response which has a greater magnitude than consensual or indirect response

31
Q

100% cross over

A

Occurs in birds - 100% cross over means there will be no consensual PLR

32
Q

50% cross over

A

Species with 50% cross over, a direct and consensual response results in equal PLRs

33
Q

Abnormal PLRs
Afferent lesions

A

Retina - retinal detachment/degeneration
Optic nerve - neuritis, avulsion, entrapment
Chiasmal lesion - tumor, traction
Optic tract - prior to split to visual and PLR pathways

34
Q

Abnormal PLRs
Efferent lesions

A

Common in CN III
High intracranial pressure, midbrain lesions, orbital fissure syndrome, retrobulbar disease

35
Q

End organ lesions - abnormal PLRS

A

Junctionopathies
High IOP
Synechiae
Lens lux/sublux
Iris atrophy
Pharmacological mydriasis (atropine, Tropicamide)

36
Q

Cataracts, SARDS, central blindness

A

Severe cataracts can be blinding
Sudden acquired retinal degeneration syndrome is acutely blinding disorder
Central or Cortical vision loss does not necessarily involve the PLR pathways

37
Q

Blindness diseases PLR should be present

A

PLRs abnormal - suspect concurrent problems
Cataracts is a common result from retinal detachment and retinal degeneration
SARDs is the most commonly caused by glaucoma/optic neuritis
Central blindness common cause is multi focal disease

38
Q

Swinging flashlight test

A

Detecting difference between two eye in how they respond to light being shone in one eye at a time
Marcus Gunn pupil

39
Q

Use of swinging flashlight test

A

Detecting unilateral or asymmetrical disease of the retina or pre chiasm optic nerve
- unilateral retinal detachment
- unilateral optic neuritis

40
Q

Horners syndrome

A

Sympathetic denervation
Classical signs - enophthalmos, ptosis, miosis, protrusion of 3rd eye lid
Other signs: conjunctival hyperemia, equine sweating, bovine nasal plenum anhydrosis

41
Q

Pathway for Horner’s syndrome

A

Hypothalamic neurons (1st order) - synapse on sympathetic pre gang neurons (2nd order) - synapse at cranial cervical ganglion on sympathetic post ganglion neurons (3rd order) - enter cranial vault = end at orbital fissure

42
Q

testing for Horner’s syndrome

A

1 drop of 10% phenylephrine
Signs should resolve partially to complete
Faster response suggests 3rd order lesion
Mydriasis: normal eye & 1st order - 60-90 minutes
2nd order Horners - 20-60 minutes
3rd order - <20 minutes

43
Q

Honers syndrome DDX - pregang disease

A

Brainstem - neoplasia, inflammatory, vascular trauma
Cervical SC - Neoplasia, trauma, FCS, IVDD, luxation
T1-3 SC - neoplasia, trauma, FCE, IVDD, luxation
Brachial plexus: trauma, avulsion, neoplasia
Mediastinal mass, trauma, carotid ligation
Neck: aggressive jug stick, accidental carotid stick, bite

44
Q

Horners syndrome DDX - post gang disease

A

Middle ear - otitis media/intera, polyp, guttural pouch disease, trauma, neoplasia
Cavernous sinus - neoplasia, inflammatory disease, vascular disease/aneurysm
Retrobulbar - neoplasia, abscess, trauma

SS - Exam 3 (28 decks)

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