Neuro Ophthalmology Flashcards
What does the Brain, spinal cord and optic nerves make up?
Central nervous system
What are cell bodies called in the CNS? PNS?
CNS- nuclei
PNS- ganglia
With vestibular disease, does the fast phase indicate towards or away from the lesion in;
Peripheral vestibular disease?
Central vestibular disease?
Peripheral- away from the lesion
Central- towards the lesion
What is the definition of nystagmus?
Rhythmic and involuntary eye movements
Which nerves are involved with pathological nystagmus (3)?
CN III OCULARMOTOR
CN IV TROCHLEAR
CN VI ABDUCENS
Which nerves innervate which extraocular muscles?
CNs III, IV & VI control the extraocular muscles originate in the brain stem, 2 out of 3 of them remain ipsilateral, 1 crosses to the extraocular muscles, which CN?
CN IV
Which CN or it’s nucleus is affected if there is ipsilateral ventrolateral strabismus and ptosis?
CN III
Which CN is affected if there is ipsilateral extorsion strabismus?
CN IV
Which CN is affected if there is contralateral extorsion strabismus?
Nucleus of CN IV
Which CN is affected if there is ipsilateral esotropia strabismus?
CN VI or it’s nucleus
In the iris what is the innervation (sympathetic v parasympathetic) to; Dilator muscles (radial) Constrictor muscles (circumferentially)
Dilator - sympathetic
Constrictor - parasympathetic
Which nerves supplies the iris dilator muscle and causes the eyelids to be open?
CN V
Why do cats have an elliptical pupil?
Only have 2 ciliary nerves (medial and lateral)
What nerves are involved in PLR?
II -> III
What is a Marcus Gunn sign?
What is this pathognomonic for?
When an illuminated eye fails to constrict (it dilates)
Unilateral retinal or prechiasmal disease
Which nerve is fired when the inner ear (3 semicircular canals), the utricle, saccule and movement of endolymph and perilymph stimulated?
CN VIII
Is the optic nerve myelinated or unmyelinated?
Myelinated
What % of the optic nerve decussates at the optic chiasm? Cat Dog Human Horses/farm animals
Cat 33%
Dog 25%
Human 50%
Horses/farm animals 10-20%
What 2 tests are used to check vision?
Maze test
Visual placing tests
Does STT test sympathetic or parasympathetic system?
And which CNs are involved in tear production?
Parasympathetic
CN V, VII
Sensory innervation of the lacrimal gland us detected by which CN?
CN V
Pilocarpine acts on the parasympathetic system and causes what to happen to the eye?
Pupil constriction
What is the test for horners?
Does it work on testing the sympathetic or parasympathetic?
How does it differentiate lesions?
Phenylephrine
Sympathetic (Denervation hypersensitivity)
Post ganglion lesion pupil dilated within 20mins,
takes 20-60mins in preganglionic
What are the clinical signs of horners syndrome?
Miosis Ptosis Enophthalmos Protrusion of the nictitans membrane Hyperthermia of the facial nerve?
First order (central) neutrons pass from the hypothalamus and exit where?
T1-T3
Second order (preganglionic) neurons pass from the spinal cord to synapse where?
Cranial cervical ganglion adjacent to the tympanic bulla
Third order (post ganglionic) fibres pass to where?
The eye
Which nerves can be affected by cavernous sinus syndrome?
Is it normally uni or bilateral?
What is the difference with this and horners?
CN III, IV, V, VI
Unilateral
Lack of sensation in this condition, not in horners
Which species does Pourfour du Petit syndrome affect?
What is the cause?
What are the clinical signs?
How quickly does it resolve?
Cats
Ear flushing
Mydriasis (good direct PLR)
Wide open palpebral fissure
Exophthalmos (no protrusion of TEL)
1week
What can cause a D/ inverted D pupil in a cat?
What nerves are affected for this to happen?
FeLV
Lymphosarcoma
Feline dysautonomia
Medial/ lateral short ciliary nerve
What type of strabismus does hydrocephalus normally cause?
Ventrolateral
What ocular signs can myasthenia gravis cause?
Weakened PLR
Facial muscle paresis
What are the clinical signs of lafora disease?
Which breeds are affected (2)?
Young or adults affected?
Twitches with visual stimulation
Miniature wire haired dachshund
Basset hound
Adult
Which species and breeds and age are affected by fibrosing esotropia?
Which muscles are affected?
Treatment?
Juvenile large/ giant breed dogs
Medial rectus and dorsal oblique muscles
During active inflammation - immunosuppressives
Post fibrosis - surgical correction
Canine distemper virus causes what clinical signs?
Conjunctivitis
KCS
Chorioretinitis
Optic neuritis, blindness
Resp signs
GI signs
What are the clinical signs for dysautonomia?
What is a test for this?
Decreased tear production
Dilated unresponsive pupils
Protruding TELs
Anorexia, vomiting, regurgitation, bradycardia, malaise, decreased appetite, dehydration
0.1% pilocarpine, will cause rapid pupil constriction
Granulomatous meningoencephalitis affects what type of dogs?
And can cause what ocular signs?
Toy breeds
Sudden onset blindness
With cerebral hypoxia blindness can occur, are PLRs normal or abnormal?
Normal
Which breeds are over represented in idiopathic facial nerve paralysis?
What are the clinical signs?
What are 2 common causes?
CKCS
Cocker spaniels
Drooping of the lip, saliva spillage
Reduced/ absent menace and palpebral
Tear production may be reduced - no blink
Hypothyroidism
Otitis media/ interna
With immune mediated retinitis (IMR) when using which light is the PLR normal and abnormal?
With IMR do they normally have a dazzle reflex?
What will show on ERG?
What is the treatment?
Normal PLR with blue light
Abnormal PLR with red light
Yes
Reduced waveforms
Steroids and doxycycline
What is the test for masticatory muscle myosotis?
What are the clinical signs?
Antibodies for Type 2M muscle fibres
Exophthalmos with TEL protrusion
Swelling/ atrophy of masticatory muscles
Pain on opening mouth
What age and size of dogs are normally affected by extraocular muscle myosotis?
What is the tx?
Does it normally recur?
Young
Large breed dogs
Systemic steroids
No
Otitis media/ interna can cause which neuro-ophthalmic diseases?
Horners syndrome
Neurogenic KCS
Facial nerve paralysis
Vestibular disease
Is sudden acquired retinal degeneration syndrome (SARDS) reversible?
Is it a sudden or long onset?
What will the results of an ERG be?
What will the results be with blue and red light testing PLR?
No
Sudden
Absent trace
Normal PLR with blue light
Abnormal PLR with red light
What can enrofloxacin cause?
Retinal degeneration
What test can be done to distinguish tora like virus causing TEL protrusion?
Phenylephrine will allow the TELs to return to normal
What are the clinical signs of thiamine deficiency?
What is the cause?
What is the treatment?
Dilated pupils (normal vision)
Inappetence
Ventroflexion of the head and neck
Raw fish diet
Rarely GI disease causing malabsorption
Parenteral vitamin B, then ora
Following an RTA was is a worse prognostic factor… miosis v mydriasis
Mydriasis
What does the trochlear CN IV innervate?
What does this do?
Dorsal oblique muscle
Inward torsion
What does trigeminal nerve CN V innervate parasympathetically?
Lacrimal gland
Which nerve is involved in conjugate eye movement?
CN VIII vestibulocochlear
Which cranial nerve innervate which ocular muscle?
Is the dazzle reflex a subcortical or cerebrocortical response?
Subcortical
If there is a lesion in the distal visual cortex will that cause;
- Blind with normal PLR
- blind with abnormal PLR
- visual with abnormal PLR
Blind with normal PLR
If there is a lesion in the optic nerve will that cause;
- Blind with normal PLR
- blind with abnormal PLR
- visual with abnormal PLR
Blind with abnormal PLR
If there is a lesion in the optic chiasm will that cause;
- Blind with normal PLR
- blind with abnormal PLR
- visual with abnormal PLR
Blind with abnormal PLR
If there is a lesion in the retina will that cause;
- Blind with normal PLR
- blind with abnormal PLR
- visual with abnormal PLR
Blind with abnormal PLR
If there optic neuritis will that cause;
- Blind with normal PLR
- blind with abnormal PLR
- visual with abnormal PLR
Blind with abnormal PLR
If there is SARDS will that cause;
- Blind with normal PLR
- blind with abnormal PLR
- visual with abnormal PLR
Blind with abnormal PLR
Which is a worse sign post RTA? Miosis or mydriasis?
Mydriasis
Internal Ophthalmoplegia causes what signs?
What is it?
Visual with dilated unresponsive pupil
Loss of parasympathetic supply from CN III oculomotor nerve
What is external ophthalmoplegia?
What does it cause?
Parasympathetic supply and somatic from CN III, IV, VI affected
Abnormal eye position - lateral strabismus, cannot retract or move eye
Which nerves pass through cavernous sinus?
CN III, IV, V, VI
If you see case which looks like horners but has a dilated pupil and decreased facial sensation what condition is it?
Cavernous sinus syndrome
What causes this?
Static aniscoria
FeLV
What type of strabismus does a hydrocephalus dog have?
Ventrolateral
What age and size dogs does fibrosing esotropia affect?
What does it cause?
Juvenile large breeds
Inward squint
Myositis of medial rectus and dorsal oblique muscles
What are the signs of facial nerve paralysis?
Cause?
Paresis Saliva drooling No blink reflex No menace response Some have KCS
Idiopathic- cockers/ CKCS
Otitis media/ interna
Which muscles are affected by masticatory myosotis?
Masseter muscle
Temporalis muscle
Explain how aqueous production occurs
What does the aqueous deliver nutrients to and remove waste from?
Lens
Cornea
Trabecular meshwork
