Large Animal Cranial Nerve and Focal Brain Disease

Question 1

what are the routes of infection for otitis media interna?

Answer 1

otitis externa
via eustachian tube

Question 2

what are the risk factors for otitis media interna?

Answer 2

respiratory tract infections
streptococcus equi in horses
wet and cold weather

Question 3

what are the diagnostics for otitis media interna?

Answer 3

ear swab
otoscopic examination and visualization of tympanic membrane
radiographs
CT scan

Question 4

what are the peripheral vestibular disease signs with otitis media interna?

Answer 4

head tilt, vestibular ataxia
facial nerve paresis or paralysis
horizontal nystagmus, fast away from head tilt
purulent discharge
head shaking

Question 5

what is the prognosis of otitis media interna?

Answer 5

better outcome in calves than older animals
chronic disease requires longer treatment and more often relapses
can be challenging

Question 6

what is the guttural pouch?

Answer 6

diverticulum attached to eustachian tube which is running from the pharynx to the middle ear of horses

Question 7

what are the most common signs of guttural pouch disease?

Answer 7

nasal discharge
epistaxis
dysphagia
laryngeal paralysis

Question 8

what diagnostics are useful for guttural pouch disease?

Answer 8

radiographs
ultrasound
endoscopy (very helpful)
sampling of infection
serology or PCR for Strep equi
CT scan

Question 9

what is temporohyoid osteoarthropathy?

Answer 9

progressive disease involving: stylohyoid bone, temporohyoid joint, temporal bone of skull, middle ear

Question 10

what facial nerve signs are associated with temporohyoid osteoarthropathy?

Answer 10

ear drop
dropped upper eye lid
dropped lips
deviated muzzle
corneal ulceration

Question 11

what is the prognosis of temporohyoid osteoarthropathy?

Answer 11

only about 50-60% return to athletic use
many have residual neurological deficits

Question 12

where is the trunk of the facial nerve?

Answer 12

stylomastoid foramen

Question 13

how does a lesion in the buccal branches of the facial nerve manifest?

Answer 13

paralyzed lips
deviated muzzle
difficulty in food prehension

Question 14

what is neuropraxia?

Answer 14

interruption of nerve function without definitive structural damagee
function returns in 3-4 weeks, very rarely does not return

Question 15

which branches of the facial nerve are most susceptible to trauma?

Answer 15

superficial buccal and auriculopalpebral branches

Question 16

what is Listeria monocytogenes?

Answer 16

small, motile, gram positive, non-spore forming, extremely resistant, diphtheroid coccobacillus

Question 17

where is listeriosis more frequently seen?

Answer 17

lower temperatures and colder climates

Question 18

how does animal-to-animal transmission of Listeria monocytogenes occur?

Answer 18

fecal-oral route

Question 19

what is most plausible for brain infection of listeriosis?

Answer 19

ascending infection along cranial nerve V

Question 20

what is the histopathology of listeriosis?

Answer 20

micro abscessation mainly in brainstem

Question 21

what are some infectious agents of otitis media interna?

Answer 21

Hemophilus somni
Mannheimia haemolytica
Mycoplasma bovis
Pasteurella multocida
Corynebacterium
Streptococcus
Staphylococcus
Pseudomonas aeruginosa

Question 22

what signs are associated with otitis media interna extending into the brain?

Answer 22

depression
ataxia
proprioceptive deficits
opisthotonos
seizures

Question 23

how does each guttural pouch communicate with the pharynx?

Answer 23

2-3cm funnel shaped orifice

Question 24

what is in the guttural pouch?

Answer 24

carotid artery
vago-sympathetic trunk
cervical ganglion
accessory nerve
vagus nerve
glossopharyngeal nerve
facial nerve
mandibular nerve
temporohyoid apparatus

Question 25

what are some common causes of guttural pouch disease?

Answer 25

empyema, Streptococcus equi mycosis (Aspergillus) tympani (air entrapment) bleeding (infection, trauma)

Question 26

how can Streptococcus equi infection be treated in the guttural pouch?

Answer 26

systemic penicillin G gelatin/penicillin composite in pouch phenylbutazone or flunixin meglumine vaccines

Question 27

what facial nerve branches are involved in ear movement?

Answer 27

caudal and internal auriculopalpebral

Question 28

what are thee buccal branches of the facial nerve involved in?

Answer 28

muzzle, food prehension

Question 29

what can Listeria monocytogenes infection cause?

Answer 29

keratoconjunctivitis sepsis mastitis abortion diarrhea

Question 30

what is the most frequently recognized form of Listeria monocytogenes?

Answer 30

encephalitis or meningoencephalitis in adult ruminants

Question 31

who is most at risk for listeriosis?

Answer 31

young ruminants

Question 32

what can cause listeriosis?

Answer 32

changing teeth, infection via tooth defects contaminated silage

Question 33

what is a common clinical finding of listeriosis?

Answer 33

compulsive walking, head pressing, circling

Question 34

how can listeriosis be diagnosed?

Answer 34

CSF: mononuclear pleocytosis, elevated protein histopathology: microabscessation mainly brainstem

Question 35

what is polioencephalomalacia associated with in ruminants?

Answer 35

thiamine deficiency high sulfur diet low-roughage diet high doses of amprolium cobalt deficiency diet toxic plants

Question 36

why is thiamine important?

Answer 36

krebs cycle: glucose energy metabolism

Question 37

how can polioencephalomalacia be diagnosed?

Answer 37

difficult CSF not diagnostic plasma thiamine levels helpful autopsy most helpful