Cross Species - Cranial Nerves Part 2

Question 1

what is horner’s syndrome?

Answer 1

loss of sympathetic innervation to the eye

Question 2

what are the 3 main risk factors of horner’s syndrome?

Answer 2

otitis media/interna

guttural pouch disease in horses

trauma/injury to the thorax, neck, or brachial plexus

Question 3

what is important to remember about the three-neuron pathway of horner’s syndrome?

Answer 3

damage can occur at any location & result in the same manifestation of horner’s syndrome

Question 4

where is the lesion in first order horner’s syndrome?

Answer 4

lesion is located from the hypothalamus to the spinal cord

Question 5

where is the lesion in second order horner’s syndrome?

Answer 5

lesion is located in T1-T3 spinal cord segments through the thorax/cervical region up to the cranial cervical ganglion

Question 6

where is the lesion in third order horner’s syndrome?

Answer 6

lesion is located from the cranial cervical ganglion to the orbit

Question 7

what is the most common form of horner’s syndrome? how is this diagnosed?

Answer 7

third order

topical 1% phenylepinephrine is applied to the affected eye - with postganglionic lesions/third order, denervation hypersensitivity develops in 2-3 weeks, which makes the eye exquisitely sensitive to low concentrations of phenylephrine, so it is applied topically & the eye is monitored for 20-60 minutes

mydriasis often occurs within 20-30 minutes with postganglionic lesion

Question 8

what are the clinical signs of horner’s syndrome? what are signs seen only in horses?

Answer 8

ptosis

miosis

enopthlamos

3rd eyelid elevations

horses only - increased sweating around the ear/face

Question 9

what cranial nerve can become damaged from otitis media?

Answer 9

cranial nerve VII paralysis

Question 10

what are the risk factors associated with otitis media resulting in cranial nerve VII paralysis?

Answer 10

external ear infections especially in dogs with floppy ears like cocker spaniels

Question 11

what are some clinical signs of otitis media & associated cranial nerve VII damage?

Answer 11

head shaking

cranial nerve VII signs - facial asymmetry, inability to blink, & KCS

horner’s syndrome

Question 12

what cranial nerves can become damaged from otitis media?

Answer 12

cranial nerve VII & cranial nerve VIII paralysis

Question 13

what are the risk factors associated with otitis interna resulting in cranial nerve VII/VIII paralysis?

Answer 13

same risk factors of otitis media

Question 14

what are some clinical signs of otitis interna & associated cranial nerve VII/VIII damage?

Answer 14

head shaking, cranial nerve VII signs (inability to blink, facial asymmetry, KCS) horner’s syndrome

signs of vestibular disease - head tilt towards the lesion, spontaneous horizontal or rotary nystagmus (fast phase away from the lesion), falling/circling towards the side of the lesion, & deafness

Question 15

what are the risk factors of facial nerve trauma/paralysis?

Answer 15

lateral recumbency in large animals

post-facial or ear surgery in small animals

Question 16

what clinical signs are associated with facial nerve trauma/paralysis?

Answer 16

facial asymmetry - ipsilateral lip droop, ear droop, ptosis

decreased to absent palpebral reflex & menace response

decreased tear production - leading to corneal ulcers

drooling from the ipsilateral lip

Question 17

what breeds may be predisposed to idiopathic facial paralysis?

Answer 17

middle aged to older dogs - pembroke welsh corgi & domestic long haired cats may be predisposed

similar to bell’s palsy in humans

Question 18

optic nerve/central blindness is associated with what damage/lesion?

Answer 18

damage to cranial nerve II or a brain lesion

Question 19

what are the risk factors associated with optic nerve/central blindness from damage to cranial nerve II/brain lesion?

Answer 19

viral, mycotic, protozoan, & parasitic infections

trauma

reticulosis

toxins - ead, ivermectin

Question 20

what clinical signs are associated with optic nerve/central blindness from damage to cranial nerve II/brain lesion?

Answer 20

acute blindness, dilated/fixed pupils, negative direct & consensual PLR, & negative menace response

Question 21

trigeminal neuritis is associated with damage to what cranial nerve?

Answer 21

cranial nerve V

Question 22

what are the risk factors & clinical signs of trigeminal neuritis?

Answer 22

risk factors - affects dogs & cats

clinical signs - unable to close mouth, unable to eat/dysphagia, may drool excessively, & signs resolve in 3-4 weeks without treatment

Question 23

what is another name for temporohyoid osteoarthropathy in horses? what cranial nerves are involved?

Answer 23

guttural pouch disease

can cause paralysis of CN VII/IX/X/XI/XII

(in the guttural pouch - IX, X, XI, XII

Question 24

what are the risk factors of temporohyoid osteoarthropathy in horses?

Answer 24

otitis media, cribbing, oral procedures for THO, empyema from strep equi equi, & mycosis of the guttural pouch (aspergillosis)

Question 25

what are the clinical signs of temporohyoid osteoarthropathy in horses?

Answer 25

sneezing, nasal discharge, head-shaking, cranial nerve VII signs, horner’s syndrome, KCS

head tilt towards the lesion, spontaneous horizontal or rotary nystagmus (fast phase away from the lesion), circling/falling towards the side of the lesion, dysphagia, & dysphonia

Question 26

nasopharyngeal polyps in cats can cause damage to what cranial nerves?

Answer 26

CN VII, CN VIII

Question 27

what is the main risk factor of nasopharyngeal polyps in cats?

Answer 27

cats with URT disease

Question 28

what are the clinical signs seen with nasopharyngeal polyps in cats?

Answer 28

head tilt, circling, ataxia, horner’s syndrome, nystagmus, & facial nerve paralysis

Question 29

listeriosis in cattle can cause damage to what cranial nerves?

Answer 29

paralysis of CN V, VII, & VIII

Question 30

what is a risk factor associated with listeriosis in cattle?

Answer 30

eating poor quality silage

Question 31

what are the clinical signs of listeriosis in cattle?

Answer 31

unilateral facial nerve paralysis, hypersalivation, & dysphagia

Question 32

what side of the face is paralyzed in this horse?

Answer 32

the right side - right ear droop, right lip droop, & ptosis

Question 33

laryngeal hemiplagia is caused by damage to what cranial nerve?

Answer 33

the recurrent laryngeal nerve - off of cranial nerve X

Question 34

what are the risk factors for laryngeal hemiplegia?

Answer 34

horses, large dogs, idiopathic, & genetic causes

Question 35

what are the clinical signs of laryngeal hemiplegia? is left-sided or right-sided more common?

Answer 35

clinical signs - roaring (inspiratory stridor), & exercise intolerance

left-sided more common than the right!

Question 36

brainstem lesions can involve damage to all cranial nerves except for?

Answer 36

cranial nerves I & II

Question 37

what are the risk factors for brainstem lesions?

Answer 37

neoplasia & vascular accidents

Question 38

what clinical signs are associated with brainstem lesions?

Answer 38

multiple cranial nerve deficits that can be unilateral or bilateral