Cross Species - Cranial Nerves Part 2 Flashcards
what is horner’s syndrome?
loss of sympathetic innervation to the eye
what are the 3 main risk factors of horner’s syndrome?
otitis media/interna
guttural pouch disease in horses
trauma/injury to the thorax, neck, or brachial plexus
what is important to remember about the three-neuron pathway of horner’s syndrome?
damage can occur at any location & result in the same manifestation of horner’s syndrome
where is the lesion in first order horner’s syndrome?
lesion is located from the hypothalamus to the spinal cord
where is the lesion in second order horner’s syndrome?
lesion is located in T1-T3 spinal cord segments through the thorax/cervical region up to the cranial cervical ganglion
where is the lesion in third order horner’s syndrome?
lesion is located from the cranial cervical ganglion to the orbit
what is the most common form of horner’s syndrome? how is this diagnosed?
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
what are the clinical signs of horner’s syndrome? what are signs seen only in horses?
ptosis
miosis
enopthlamos
3rd eyelid elevations
horses only - increased sweating around the ear/face
what cranial nerve can become damaged from otitis media?
cranial nerve VII paralysis
what are the risk factors associated with otitis media resulting in cranial nerve VII paralysis?
external ear infections especially in dogs with floppy ears like cocker spaniels
what are some clinical signs of otitis media & associated cranial nerve VII damage?
head shaking
cranial nerve VII signs - facial asymmetry, inability to blink, & KCS
horner’s syndrome
what cranial nerves can become damaged from otitis media?
cranial nerve VII & cranial nerve VIII paralysis
what are the risk factors associated with otitis interna resulting in cranial nerve VII/VIII paralysis?
same risk factors of otitis media
what are some clinical signs of otitis interna & associated cranial nerve VII/VIII damage?
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
what are the risk factors of facial nerve trauma/paralysis?
lateral recumbency in large animals
post-facial or ear surgery in small animals
what clinical signs are associated with facial nerve trauma/paralysis?
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
what breeds may be predisposed to idiopathic facial paralysis?
middle aged to older dogs - pembroke welsh corgi & domestic long haired cats may be predisposed
similar to bell’s palsy in humans
optic nerve/central blindness is associated with what damage/lesion?
damage to cranial nerve II or a brain lesion
what are the risk factors associated with optic nerve/central blindness from damage to cranial nerve II/brain lesion?
viral, mycotic, protozoan, & parasitic infections
trauma
reticulosis
toxins - ead, ivermectin
what clinical signs are associated with optic nerve/central blindness from damage to cranial nerve II/brain lesion?
acute blindness, dilated/fixed pupils, negative direct & consensual PLR, & negative menace response
trigeminal neuritis is associated with damage to what cranial nerve?
cranial nerve V
what are the risk factors & clinical signs of trigeminal neuritis?
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
what is another name for temporohyoid osteoarthropathy in horses? what cranial nerves are involved?
guttural pouch disease
can cause paralysis of CN VII/IX/X/XI/XII
(in the guttural pouch - IX, X, XI, XII
what are the risk factors of temporohyoid osteoarthropathy in horses?
otitis media, cribbing, oral procedures for THO, empyema from strep equi equi, & mycosis of the guttural pouch (aspergillosis)
