Otology Flashcards
Ear label (apex, scapha, cutaneous marginal pouch, median/rostral margin, lateral/caudal margin)
T or F: Breed matters more than heat/temp of the ear canal
T
No temp/humidity difference between diseased and normal ears.
T or F: environmental humidity can affect ear canal humidity
F
Do ear canals with or without hair have a higher temperature
Canals WITHOUT hair are hotter
Canals WITH hair are cooler
Which breed has higher ear canal temperatures than other dogs
GSD
Breed with ceruminous gland hyperplasia
Cocker spaniels
Pendulous ears vs hair relationship
Pendulous ears WITH hair get more otitis
(but maybe actually more related to breed)
Erect ears vs hair relationship
Erect ears +/- hairs get less otitis
(but maybe actually more related to breed)
Predisposing, Primary, or Perpetuating: Conformation (hair, anatomic stenosis, pendulous pinnae)
Predisposing
Predisposing, Primary, or Perpetuating: Otodectes cynotis
Primary
Predisposing, Primary, or Perpetuating: excessive moisture (swimming)
Predisposing
Predisposing, Primary, or Perpetuating: trauma from cotton swabs
Predisposing
Predisposing, Primary, or Perpetuating: hair plucking
Predisposing
Predisposing, Primary, or Perpetuating: atopic dermatitis
Primary
Predisposing, Primary, or Perpetuating: bacterial/yeast infection
Perpetuating
Predisposing, Primary, or Perpetuating: otitis media
Perpetuating
Predisposing, Primary, or Perpetuating: Hypothyroidism
Primary
Predisposing, Primary, or Perpetuating: pemphigus foliaceus
Primary
Predisposing, Primary, or Perpetuating: primary idiopathic seborrhea, juvenile cellulitis, sebaceous adenitis
Primary
Definition of predisposing factor
- Facilitate inflammation by permitting alteration of
microenvironment - Establishment of secondary infections
Definition of primary cause
Conditions or disorders that initiate the inflammatory process
What is the most common primary cause of otitis in dogs
Allergic disease
What are the 3 most common causes of otitis in cats
Parasites
Polyps
Allergic disease
What percent of dogs with atopic dermatitis have otitis as their ONLY clinical sign?
10%
What percent of dogs with CAFR have otitis as their ONLY clinical sign?
25%
What is the definition of a perpetuating factor
*Sustain and aggravate the inflammatory process
- Prevent resolution of the otitis externa
*Worsen the otitis externa
Chronic otitis media can lead to ______: a cystic mass near the Eustachian tube
Aural cholesteatoma
Label a pinna (lateral process of antitragus, medial process of antitragus, intertragic incisure, tragis, medial crus helix, tragohelicine incisure, lateral crus helix, anthelix)
*Helix rostrally
*Tragus laterally
*Antitragus caudally
*Anthelix medially
*Intertragic incisure
Routes of infection for otitis media (2)
1) Extension of OE through TM
2) Via eustachian tube
What percent of dogs with chronic recurrent OE develop OM?
89%
(73% still had intact TM! Intact TM does NOT rule out OM)
Which bacteria are most common in canine OM?
-Staphylococcus pseudintermedius
-Pseudomonas aeruginosa
T or F: Malassezia can cause OM
True, in 23.7% of sampled ears in one study!
Breed with PSOM
CKCS
Clinical signs of PSOM
-Head and neck scratching, neurological signs, hearing
loss, otic pruritus, abnormal yawning, head tilt, facial paralysis, or vestibular disturbances
-Intact tympanic membrane, mucoid exudate
Signs of facial nerve paralysis (3)
*Drooping of ear/lip
*Drooling saliva
*Absent palpebral reflex
What eye sign can be related to OM?
Neurogenic
keratoconjunctivitis
sicca (KCS)
Which nerve in the middle ear can cause Dry Nose (xeromycteria)
Parasympathetic
Which nerve in the middle ear can cause Horner’s syndrome
Sympathetic nerve
Signs of Horner’s Syndrome
- Ptosis
-Drooping of upper lid - Miosis
-Contraction of pupil - Enophthalmos
-Backward displacement of
eyeball
into the orbit - Protrusion of nictitating
membrane
Signs of Otitis INTERNA
*Horizontal
nystagmus
*Head tilt, falling, rolling
to affected side
*Asymmetric ataxia
*Hearing loss
Where do you put your cone for otoscopic exam within pinnal structures?
Intertragic incisure
What is the relationship between BW and length of ear canal
Linear relationship exists between BW and ear canal volume
(more drops in larger dogs)
Where are there more hairs: Proximal or distal ear canal
Proximal
Decrease in number
from distal to proximal
What type of gland are ceruminous glands
-Modified apocrine glands
-Located in the deeper dermis
below the sebaceous glands
-Ducts open into either the hair
follicle or onto the surface of
the external ear canal
Who has a faster epithelial migration: the Pars tensa or Pars flaccida?
Pars flaccida!
-Pars tensa = 96.4 μm/d; Pars flaccida = 225.4 μm/d
Is epithelial migration mostly radial or centrigual
Radial
What does the TM look like on histopath? Layers?
– Outer and inner epithelium
– Core of collagen
– Hairless, glandless
Label
Chorda tympani, right ear, dog. The chorda tympani ( arrow ) courses dorsally across the neck of the malleus ventral to the muscular process of the malleus (Mp), in close proximity to the pars tensa. The stapes (S) is anchored in the oval or vestibular window and the foot plate ( arrowhead ) is clearly visible in the opened vestibule (V). The stapes and incus (I) articulate to form the incudostapedius joint.
Ways feline middle ear is different from dog:
*Divided by a septum into 2 separate tympanic
cavities; connected through a foramen between
septum and petrous bone
*Dorsolateral (pars tympanica)
–Auditory ossicles, ostium of auditory tube, tympanic
membrane
–Smaller of the two
*Ventromedial (pars endotympanica)
–Air-filled tympanic bulla
Label middle ear, part of inner ear
Right ear, rostral view, dog. The middle ear has three main compartments. The epitympanic recess ( arrow ) is the smallest, most dorsal compartment occupied by the articulated malleus and incus (I). The next largest is the tympanic cavity proper (Tp) demarcated laterally by the tympanic membrane (torn in this image) and medially by the promontory of the petrous portion of the temporal bone (P). The largest is the ventral compartment (V) surrounded by the bone of the tympanic bulla ( asterisk ). Ventral bony ridge of the external acoustic meatus ( double asterisk ); stapes ( arrowhead ). Bs, brainstem; C, cochlea; Cr, cerebellar cortex; E, external ear canal; F, facial nerve in its facial canal; S, incomplete septum bulla.
Is the oval or round window adjacent to the pars flaccida?
Oval
Does the foot of the stapes touch the oval or round window?
Oval
What is the other name for the oval window
vestibular
What is the other name for the round window
cochlear
What is the eustachian tube
- Extends from
nasopharynx to tympanic
cavity - 8mm long
- 1.5mm diameter
- Equalizes pressure
- Cartilagenous,
junctional, osseous
Where is the ideal myringotomy site?
Ventocaudal
Name of the fluid inside the inner ear
Perilymph
Portion of spiral passage that ascends into cochlea
Scala vestibuli
Portion of spiral passage that exists cochlea
Scala tympani
What is inside the cochlea duct (that runs alongside the scala vestibuli and scala tympanic
endolymph
What sends nerve impulses to the brain due to vibrations from the basilar membrane in the cochlea?
Organ of corti via cochlear nerve
What cells are inside the organ of corti, to induce nerve transduction
Hair cells
T or F: most PSOM cases have bacteria isolated via traditional culture
False
Due to increased production of mucus vs decreased drainage via eustachian tube