Ear Questions Flashcards
(115 cards)
1
Q
- Which area of the ear canal has more glands and follicles in the dog?
A
a. Vertical canal
2
Q
- What is the process of natural migration in the epidermis and tympanum of the canine ear canal?
A
a. Mainly in out pattern with some centrifugal epithelial migration across the tympanum and up the ear canal to the surface
3
Q
- What cranial nerves travel through the tympanic bulla and may be disrupted during a myringotomy?
A
a. CN VII (Facial) and CN IX (Glossopharyngeal)
4
Q
- What is the function of the Eustachian tube? (3 functions)
A
a. Equalize air pressure between the middle ear and nasopharynx
b. Protect middle near from nasopharyngeal pathogens
c. Ventilation and drainage of the middle ear
5
Q
- Describe the common clinical signs of PSOM in dogs.
A
a. Moderate to severe pain around the head/neck with or without neurologic abnormalities
b. Viscous, non-infected mucus plug in the middle ear, accompanied by a bulging tympanic membrane (not always, but common)
6
Q
- Describe this CT image and give 3 differentials for the condition.
A
Answer:
a. Right-sided fluid attenuation and mildly enhancing soft tissue in the bulla, extending to the horizontal ear canal with multifocal lysis of the right bulla
b. Differentials: abscess is primary concern, rule out cholesteatoma and neoplasia with secondary infection
7
Q
- Be able to label the following parts of the ear canal.
A
Answers: a = pinna, b = vertical canal, c = horizontal canal, d = facial nerve, e = external ear,
f = middle ear, g = Eustachian tube, h = tympanic bulla, i = otic nerve, j = auditory ossicles,
k = tympanic membrane
8
Q
- Be able to label this image. What species is that?
A
Answers:
- This is a cat (malleus is much straighter in cats)
- Included items to label:
o Malleus (bony hook)
o Pars tensa (majority of visible ear drum)
o Pars flaccida (small dorsal portion)
9
Q
- Be able to label this image.
A
Answers: 1 = pars flaccida, 2 = pars tensa, 3 = manubrium of the malleus
10
Q
- Where do squamous cell carcinomas occur on in cat and dog ears?
A
a. Dorsal ear tips and lightly haired preauricular areas most commonly
11
Q
- At what angle is the tympanic membrane oriented and where it is attached in the dog and cat?
A
a. 30 – 45 degree angle
b. Attached to medial aspect of external acoustic meatus
12
Q
- What portion of the ear drum should be punctured during a myringotomy?
A
a. Posteroventral quadrant, below the manubrium attachment in the pars tensa
13
Q
- What are the three types of cleaning agents used for the ear?
A
a. Ceruminolytics
b. Mild cleansers
c. Antiseptics and drying agents
14
Q
- Define primary, secondary, predisposing, and perpetuating causes in dogs and cats with otitis.
A
a. Primary = creates disease in the normal ear
b. Secondary = creates disease in the abnormal ear
c. Predisposing = increase risk for development of otitis externa
d. Perpetuating = inflammation of the ear canal and middle ear interferes with resolution of otitis to promote more secondary infections
15
Q
- Describe these biopsy findings and give potential differential for mass removed from a dog’s ear canal.
A
Answer:
a. Squamous epithelium partially surrounding a cystic structure with abundant lamellar eosinophilic keratin debris
b. Possible etiology = cholesteatoma
16
Q
- Which of the following classifications of ear disease creates ear disease in a normal ear? (multiple choice)
a. Primary factors
b. Secondary factors
c. Perpetuating factors
d. Predisposing factors
A
a. Primary factors
17
Q
- List 3 – 5 primary, secondary, predisposing, and perpetuating causes of otitis in dogs and cats.
A
a. Primary:
i. Allergy (contact, atopy, food allergy)
ii. Autoimmine = Pemphigus foliaceus, bullous pemphigoid, erythema multiforme
iii. Endocrine = Cushings disease, hypothyroidism
iv. Epithelialization disorders = Primary idiopathic seborrhea, zinc responsive dermatosis
v. Foreign bodies
vi. Dermatophytosis
vii. Parasites (Demodex, Otodectes cynotis, Otobius megnini)
b. Secondary:
i. Bacterial infection (Staph, Strep, Enterococcus, Pseudomonas, Proteus, E. coli, Corynebacterium)
ii. Aspergillus or Penicillium fungal species
iii. Topical irritant reactions
iv. Overcleaning
v. Malassezia pachydermatis infection
c. Predisposing:
i. Conformation = Excessive hair growth, pendulous pinnae, stenotic canals
ii. Excessive moisture from swimming or over-bathing
iii. Neoplasms
iv. Ceruminous cystomatosis
v. Feline inflammatory polyps
vi. Primary secretory otitis media (PSOM)
d. Perpetuating:
i. Excessive debris production and altered migration of epithelium
ii. Ear canal lichenification
iii. Thickened tympanic membrane or healing with a permanent hole
iv. Calcification due to chronic disease
v. Gland blockage or dilation
vi. Cholesteastomas
vii. Otitis media
18
Q
- Describe characteristics that differentiate cholesteatomas from middle ear neoplasia and chronic otitis media/externa on CT.
A
a. CT will show contrast enhancement of tissue directly adjacent to the bone in cholesteatomas, but neoplasias extending into the middle ear will contrast enhance more widely
b. Chronic otitis media/externa will not expand the bulla, unlike cholesteatomas
19
Q
- Describe the clinical signs and location of ceruminous cystomatosis in cats.
A
a. Location = concave pinna, external orifice, ear canal
b. Clinical signs = multiple coalescing papules/vesicles/nodules/plaques that are blue-brown-black and express yellow fluid when punctured
c. Secondary otitis externa can occur
20
Q
- What are the suspected causes of primary secretory otitis media in dogs?
A
a. Increased mucus production in the middle ear
b. Decreased middle ear drainage through the auditory tube
21
Q
- What frequencies are most affected in hearing loss by older dogs, and what histological findings correlate with this change? (2 changes)
A
a. 6 – 12 kHz
b. Geriatric dog cochlea changes:
i. Reduce outer and inner hair cell counts
ii. Reduced spiral ganglion packing density
iii. Reduced stria vascularis cross sectional area
22
Q
- How do Pseudomonas species form biofilms and what are biofilms made of?
A
a. Secrete exopolysaccharides, such as alginate, which attach to surfaces and block bacterial removal and phagocytosis by white blood cells
23
Q
- What structure is this biopsy of?
A
a. Ear cartilage sample
24
Q
- What is the most common effective treatment of PSOM in dogs? What is its prognosis for cure?
A
a. Myringotomy with flushing of the middle ear – will need to be repeated in the future, cure is unlikely
25
25. What is the tissue of origin of feline inflammatory polyps?
a. Epithelial lining of tympanic bulla and auditory tube
26
26. What parasite can cause otitis in cats specific to the northwest pacific? How is it diagnosed?
a. Mammomonogamous auris
b. Can see swimming behind the ear drum on otoscopic exam
27
27. What condition can also be present in dogs with Primary Secretory Otitis Media?
a. Caudal Occipital Malformation
28
28. A patient presents with a history of chronic unilateral otitis externa. On otoscopy, polypoid masses are noted along the canal. Biopsy of these masses yields eosinophilic granuloma or dermatitis, intraepidermal eosinophilic microabscesses, and areas of degenerate collagen. What is the likely diagnosis in this case and what is treatment?
a. Canine proliferative eosinophilic otitis externa
b. Treatment = surgical excision is curative or may show recurrence in future
29
29. What are four theories of the etiology of aural cholesteatomas?
a. Primary Acquired = Eustachian tube dysfunction causes invagination of TM into bulla
b. Secondary Metaplasia Acquired = chronic inflammation causes transformation of ciliated respiratory epithelium into stratified squamous epithelium in bulla
c. Secondary Migration Acquired = Break in TM allows stratified squamous epithelium to enter the bulla
d. Secondary Invasion Acquired = Break in basement membrane allows TM keratinizing epithelial cells into the subepithelial space
30
30. Name 4 - 5 common techniques for treating aural hematomas.
a. Curvilinear incision and flushing with sutures
b. Closed suction drainage
c. Placement of cannula for intermittent drainage
d. CO2 laser with partial and full thickness circular incisions
e. Daily needle drainage
31
31. What are the clinical signs of feline and canine inflammatory aural polyps? How do they differ?
a. Canine = otorrhea (fluid drainage from the ear), ear scratching, head shaking, otitis
b. Feline = otitis externa, neurologic signs (Horner’s, head tilt, ataxia, facial paralysis)
32
32. What is the mechanism of furosemide ototoxicity? (2 ways)
a. Causes concentration of other ototoxins in cochlear endolymph (cisplatin, aminoglycosides) and blocks active potassium transport in stria vascularis
b. Decreases endocochlear potential, reduces amplitude of vestibulocochlear nerve action potential, causes edema and degeneration of stria vascularis
c. Causes reversible, auditory ototoxicity
33
33. What is the difference in origin of aural/nasopharyngeal polyps and nasal hamartomas in cats?
a. Aural/Nasopharyngeal polyps originate from the lining of the tympanic bulla or auditory tube
b. Nasal hamartomas originate from the nasal cavity tissue
34
34. A male cat < 4 years old presents with signs of bilaterally symmetric, tightly adhered crusts with erythematous plaques and ulcers on the concave pinnae only. Give three differentials for this condition.
a. Pemphigus foliaceus, feline proliferative necrotizing otitis externa, Otodectes cynotis infestation
35
35. Describe 5 predisposing and primary factors involved in external ear canal lesions in alpacas.
a. Ectoparasites, foreign bodies, pruritic/painful diseases (lacerations, frostbite, dermatophytosis, dermatophilosis)
36
36. What is the presumed etiology of feline proliferative and necrotizing otitis externa?
a. T cell induced caspase-positive epidermal keratinocyte apoptosis, similar to erythema multiforme (external pathway of apoptosis)
37
37. What are the recommended treatments for ceruminous cystomasosis in cats?
a. Laser therapy (best option)
b. Vertical canal resection or TECA may be needed in cases of recurrent otitis and failure to control with medications
38
38. Describe the clinical appearance of ceruminous gland adenomas versus adenocarcinomas? What is their behavior?
a. Adenoma = small, multiple, pedunculated and pigmented masses that are variably irregular and firm
b. Adenocarcinoma = irregular, raised to plaque-like, variable ulcerated and locally invasive tumors
c. Behavior of malignant form = 50% metastasize to regional lymph nodes, lungs, and viscera
39
39. True/False – Juvenile cellulitis can start with otitis externa and pinnal disease.
a. True
40
40. Describe this finding on CT scan in a dog.
Answer:
a. Left tympanic bulla is enlarged with soft tissue material, bony lysis and osteoproliferation of the bulla wall with cochlear lysis
b. Suspect cholesteatoma due to lack of widespread contrast enhancement
41
41. True/False – Pseudomonas bacteria tend to be susceptible to beta lactam antibiotics.
a. False – most are resistant via porins and efflux pumps in the cell walls along with beta lactamase enzymes
42
42. What are feline hamartomas?
a. Inflammatory, expansile polyps of the nasal turbinates
43
43. Rod-shaped bacteria are found on cytology of a dog’s ear. What are four likely differentials for the species of bacteria that were found?
a. Pseudomonas aeruginosa
b. Corynebacterium spp.
c. E. coli
d. Proteus mirabilis
44
44. A 10 year old cat presents with a history of otitis externa that is recurrent. On physical examination, the following is seen. What is the diagnosis of this condition and what are the expected biopsy findings upon removal?
Answer = ceruminous cystomatosis of cats
Biopsy findings = ceruminous gland cystic hyperplasia – stratified squamous epithelium lined with multiple cysts, filled with inspissated material or clear liquid
45
45. What is the etiology of canine leproid granulomas?
a. Infection by saprophytic mycobacterium transmitted by biting insects or traumatic inoculation
46
46. In what breed of cat do inflammatory polyps appear to be congenital?
a. Maine Coons
47
47. What are five reasons to perform a TECA-LBO?
a. Chronic otitis with canal epithelial hyperplasia/stenosis/calcification
b. Unresponsive otitis media
c. Cholesteatoma
d. Neoplastic infiltration of ear canal/middle ear
e. Severe trauma to the ear canal
f. Inability to medicate
48
48. Which of the following classifications of ear disease increases the risk of developing otitis externa, typically working in conjunction with the other factors? (multiple choice)
a. Primary factors
b. Secondary factors
c. Perpetuating factors
d. Predisposing factors
d. Predisposing factors
49
49. What are the most common external ear canal tumors in dogs (2) and cats (3)?
a. Dogs = ceruminous gland adenomas and adenocarcinomas
b. Cats = nasopharyngeal polyp, squamous cell carcinoma, ceruminous gland adenocarcinoma
50
50. How are feline inflammatory polyps treated? (3 ways)
a. Traction avulsion, ventral bulla osteotomy, total ear canal ablation
51
51. What is the advantage of CT vs. MRI when imaging a dog with ear infections?
a. CT = better define bony structures, look for bony lysis or expansion
b. MRI = better define soft tissue structures (esp. inner ear labyrinth fluid and intracranial structures)
52
52. What are the most common clinical signs of otitis externa in dogs and cats?
a. Erythema, swelling, scaling, crusting, alopecia of the pinna and canal
b. Otic discharge and malodor
c. Pain on palpation of auricular cartilage and head shyness
d. Secondary pyotraumatic dermatitis of lateral face and/or aural hematomas
53
53. What five nerves innervate the pinna, canal, and nearby anatomy in the dog.
a. Great Auricular:
i. Convex pinna sensory innervation
b. Sensory innervation by branches of facial nerve: middle internal auricular, caudal internal auricular, lateral internal auricular nn. **Close to GA nerve**
i. Concave pinna central and caudal areas
ii. Vertical ear canal
c. Mandibular branch of trigeminal nerve:
i. Rostral pinna sensory innervation
d. Auriculotemporal branch of mandibular branch of trigeminal nerve:
i. Medial horizontal ear canal sensory innervation
e. Auriculopalpebral nerve (branch of facial nerve): **close to AT nerve**
i. Eyelid motor innervation
54
54. A dog presents with a head tilt. Is this indicative of otitis externa, otitis media, or both?
a. Head tilts can occur with both otitis media and otitis externa
55
55. Be able to describe the pros and cons of TECA, bulla osteotomy, lateral resection and vertical ear canal resections in animals.
56
56. Describe the appearance of the feline inflammatory polyp on otoscopy and CT scan.
a. Otoscopy/Endoscopy = pink/reddish and rounded, multilobular in some cases, often ulcerated. Can also cause protrusion of the TM if it has not ruptured into the external canal.
b. CT = rounded, soft tissue mass with defined borders and rim enhancement
57
57. A dog presents with facial palsy and Horner’s syndrome, along with an ear infection. What areas of the ear does this infection involve?
a. Otitis media and Otitis externa
58
58. Describe how the normal ear cleans itself. (3 ways)
a. The tympanum in the dog moves in a centrifugal pattern of cell migration (moves away from the center)
b. Cells slowly migrate along the canal out towards the canal entrance, bringing debris with them
c. Jaw movement also helps move ear wax outwards to the ear canal entrance
59
59. Where on the tympanum should the myringotomy be performed (1, 2, 3)?
Answer: 2 (pars tensa – rostroventral portion)
60
60. What are 2 common risk factors for aspergillus otitis in dogs and cats.
a. Immune suppression
b. Grass awns (dogs)
61
61. Name at least 3 clinical signs of a deep infection following TECA-LBO.
a. Para-aural fistulas/draining tracts
b. Pain/swelling around the previous incision site
c. Acute pain when opening the mouth
d. Head tilt on affected side
e. Fever/inflammatory leukogram (less common)
62
62. List 3 common clinical signs of aural cholesteatomas.
c. Chronic otitis
d. Neurologic signs = ataxia, facial palsy, head tilt
e. Pain/inability to open jaw
f. Respiratory difficulty (due to expansion)
63
63. Define presbycusis and give the mechanisms for its development.
a. Definition = Age-related hearing loss reduce auditory perception with age
b. Mechanisms:
i. Sensorineural +/- conduction through the middle ear effects
ii. Peripheral +/- central neurologic changes
64
64. What is the presentation of a dog with canine leproid granulomas? Name the common breeds.
a. One to multiple discrete, nodular, dermal or SC pyogranulomatous inflammatory masses on the pinnal base +/- head and distal limbs
b. Most common in boxers and boxer crosses, or other short-coated dog breeds
65
65. How are tympanostomy tubes hypothesizes to provide relief in dogs with primary secretory otitis media?
a. Relieve negative pressure in the bulla through ventilation of the middle ear, which would lead to fluid accumulation. They do not appear to provide drainage.
66
66. What is the presentation of chronic obstructive otitis externa?
a. Marked ceruminous gland hypertrophy and hyperplasia, acanthosis, and proliferative soft tissues that cause stenosis and obstruction of the external ear canal, eventually ending in calcification of the canal
67
67. What are 3 - 4 causes of peripheral and five causes of central vestibular disease?
a. Peripheral:
i. Nasopharyngeal polyp
ii. Otitis
iii. Head trauma
iv. Aminoglycoside medications
v. Hypothyroidism
b. Central:
i. Head trauma
ii. Chiari-like malformation
iii. Tumor (primary or metastatic)
iv. Brain hemorrhage
v. Meningoencephalitis/infectious encephalitis
68
68. By what ratio does the tympanic cavity volume differ between brachycephalics and nonbrachycephalics? Why does this matter?
a. 1:3 (brachycephalic cavities are 1/3 smaller, so smaller volumes of flush are recommended during ear flushing)
69
69. Describe these MRI findings in a dog.
a. Expansile left bulla containing material isointense to brain tissue (left side) or heterogenous hyperintense to brain tissue (right)
70
70. What is the recommended treatment for cholesteatomas?
a. Surgery – lateral/ventral approach, TECA-LBO if otitis externa present
i. Goal = complete removal of diseased tissue without translation of squamous epithelium into the bulla
71
71. What is the etiology of an aural hematoma?
a. Shearing forces in the auricular cartilage created by the dog shaking its head/scratching ears cause pinnal vascular trauma and cartilage separation, leading to accumulation of hemorrhagic fluid in the concave surface of the pinna.
72
72. What 2 fungal organisms are commonly implicated in human otomycosis?
a. Candida and Aspergillus spp.
73
73. What are five clinical signs of feline hamartomas?
a. Progressively worsening signs
i. Stertorous breathing
ii. Sneezing
iii. Open-mouth breathing
iv. Serous nasal discharge
v. Epistaxis
vi. Sinonasal deformation
74
74. What is the most common risk of benign neglect in aural hematoma treatment?
a. Fibrosis and pinnal deformation during healing
75
75. What are the common fungal organisms found in dog (3) and cat (2) ears under normal circumstances and in infection?
a. Dog
i. Infection and normal ears = Malassezia pachydermatis
ii. Infection = Candida spp. also occasionally present, along with Aspergillus and Penicillium spp.
b. Cat:
i. Infected ears only = Malassezia pachydermatis AND lipid-dependent Malassezia species, Aspergillus spp. also occasionally found
76
76. What are the clinical signs and signalment of proliferative and necrotizing otitis externa in cats?
a. Signalment < 1 yo usually (usually 2 – 6 months)
b. Signs = dark brown-black, proliferative, plaque-like to coalescing lesions with secondary thick exudate and otitis and minimal pruritus/pain on the concave pinnae +/- vertical ear canal
77
77. What are three proposed etiologies of feline inflammatory polyps?
a. Congenital (Main coons)
b. Response to chronic viral infection (herpesvirus, calicivirus)
c. Response to chronic middle ear and upper respiratory infection and inflammation
78
78. Describe the findings in these four CT images of a bulla
top left = normal tympanic bulla
top right = fluid-filled tympanic bulla and normal wall
bottom left = fluid filled tympanic bulla with thickened, irregular wall
bottom right = lysis of wall with fluid-filled tympanic bulla
79
79. List five predisposing factors to otomycosis.
a. Warm, humid climates, immune compromise
b. Cleansing ears with sticks or swabs
c. Swimming
d. Pruritus elsewhere on the body
e. Non-sterile oil use in the ear
f. Grass awns in the ear
80
80. What are five common bacterial inhabitants of the normal canine ear and the diseased canine ear?
a. Normal = S. pseudintermedius, S. schleiferi ssp. coagulans, coagulase negative Staph species, Bacillus spp, Streptococci, Micrococcus, Corynebacterium
b. Diseased = S. pseudintermedius, Pseudomonas aeruginosa, Proteus mirabilis, E. coli, beta-hemolytic streptococci, Corynebacterium, Enterococcus spp
81
81. What breed of dog is predisposed to primary secretory otitis media?
a. Cavalier King Charles Spaniel
82
82. How does the equine ear anatomy differ from dogs and cats? (3 ways)
a. Lack of glands in the osseous ear canal
b. Sterile environment in proximal ear canal
c. Extremely narrow osseous portion of external ear canal makes visualizing the TM nearly impossible
83
83. How does epithelial migration occur in the canine tympanum?
a. Predominantly radial (linear) movement from in to out
b. <10% move centrifugally from in to out
84
84. Name 4 negative prognostic indicators for resolution of aural cholesteatomas in dogs.
a. Inability to open mouth/pain opening the mouth
b. Lysis of tympanic bulla/temporal bone
c. Bulla expansion
d. Culture of Pseudomonas from the middle ear
85
85. How do brachycephalic bulla walls differ from nonbrachycephalic tympanic bulla walls?
a. The brachycephalic bulla wall is thicker and varies by location (rostroventral thicker than caudoventral)
b. Nonbrachycephalic wall which is of thinner, uniform thickness
86
86. What are the two main types of hearing loss?
a. Conductive hearing loss = occlusion of canal by exudates/stenosis, tympanic membrane rupture
b. Sensorineural hearing loss = altered physics/hydrodynamics of inner ear or abnormality/damage in receptor cells of cochlea or part of auditory pathway
87
87. What are the clinical signs of craniomandibular osteopathy? What breeds are predisposed?
a. Difficulty opening the mouth, recurrent otitis, chronic facial swelling
b. Westies, Scotties, Cairn terriers
88
88. Describe signs of unilateral and bilateral vestibular syndromes
a. Unilateral = head tilt, ataxia, falling, leaning, rolling, circling, nystagmus (spontaneous/positional), positional strabismus
b. Bilateral = head swaying, no head tilt, loss of balance to either side, symmetric ataxia with crouched posture, inability to elicit physiologic nystagmus
89
89. Label the portions of the equine ear canal.
Answer:
a. CN V
b. Cerebellum
c. Guttural pouch
d. Tympanic membrane
e. Occipital bone
f. External ear canal
g. Spiral canal
h. Petrous temporal bone
j. Tympanic bulla
k. Basisphenoid bone
90
90. Describe the following MRI findings.
a. Left facial nerve is thickened and hyperintense to grey matter with mixed signal density in the left tympanic bulla
91
91. What are the characteristics of the types of otitis externa – suppurative, erythemato-ceruminous, proliferative? What infections/inflammation are seen?
a. Suppurative
i. Presence of neutrophils in the external ear canal (rods infections common)
b. Erythemato-ceruminous
i. Erythematous ear with wax aural discharge, generally associated with gram+ infections
c. Proliferative – marked ceruminous gland hyperplasia, acanthosis and proliferation of soft tissues resulting in stenosis and obstruction of external ear canal
i. Changes occur in weeks to months
ii. Irreversible occlusion of the canal
92
92. What are 3 possible complications of aural polyp removal?
a. Horner’s syndrome
b. Vestibular disease
c. Facial nerve paralysis
d. Chronic otitis media/interna
e. Later regrowth
93
93. What is the type and process of aminoglycoside ototoxicity? What 3 areas are affected?
a. Permanent hearing loss usually results, affecting high frequencies first
b. Causes sensory hair cell loss from the base at the cochlear spiral then moves towards the apex
c. Cochlear nerve degeneration follows hair loss
d. Stria vascularis degeneration only occurs late in toxicity
e. Gentamicin impairs balance through loss of sensory hairs in the vestibule
94
94. How can emollients cause hearing loss?
a. Emollients can cause conductive hearing loss because they are occlusive via the residual ointment left in the ear
95
95. What is the etiology of Horner’s syndrome?
a. Oculosympathetic dysfunction that results from disruption of the sympathetic innervations to the eye and adnexa, often due to damage to the sympathetic innervation on the affected side (central, preganglionic, or post-ganglionic locations)
b. Causes = trauma, iatrogenic, neoplastic, secondary to infection (otitis media), idiopathic
96
96. What are 5 common clinical signs of Horner’s syndrome?
a. Can see anisocoria, miosis, head tilt, ptosis, enophthalmous, prolapsed nictitans, lack of blink response
97
97. What is the prognosis for a patient with Horner’s syndrome? How do you treat it?
a. Most resolve without treatment in 4 – 8 weeks if they are not neoplastic and any underlying otitis is treated
b. Symptomatic therapy is helpful = eye drops to prevent corneal damage without blinking, steroids can reduce inflammation (systemically)
98
98. List five ototoxic medications or vehicles for medications in the treatment of otitis externa.
a. Aminoglycosides (gentamicin, amikacin, tobramycin)
b. Ceruminolytics (prolonged contact)
c. Topical chlorhexidine
d. Propylene glycol
e. Polymixin B
99
99. What is the suggestive mechanism of gentamicin ototoxicity?
a. Binds to mammalian mitochondrial RNA with similar subunits to bacterial versions
b. Causes oxidative stress due to overproduction of reactive oxygen species
100
100. Contrast traction removal versus surgical removal of a feline inflammatory polyp in the ear.
a. Traction removal
i. Less risk of complications post-operatively
ii. Minimally invasive
iii. Increased risk of leaving portions of the polyp, which promotes recurrence
b. Surgical removal (VBO)
i. Increased risk of complications post-operatively
ii. Allows examination of both ear chambers
iii. Preferred in cases of recurrence of the polyp and recommended in cases where the patient has horizontal ear canal stenosis
101
101. Where would you perform a myringotomy (on a clock face) and why?
a. 5 oclock in left ear, 7 oclock in right ear
b. Avoid stria mallearis and umbo region (site of origin of epithelial migration)
102
102. Describe the four neuroanatomical structures associated with the ear – their identities, location, and function.
a. Facial nerve (CN 7)
i. Function = sensory to 2/3 of tongue/palate, control muscles of facial expression, innervation of lacrimal/nasal mucosa glands and salivary glands
ii. Location = passes along facial canal above vestibulocochlear nerve and exposed to middle ear at the vestibular window
b. Ocular sympathetic tract
i. Function = sympathetic tone to periorbita and eyelids, as well as iris dilator muscle
ii. Location = Portion of axons pass through tympanic bulla
c. Vestibulocochlear nerve (CN 8)
i. Function = convert information from vestibular receptors to control balance
ii. Location = enclosed with facial nerve when passing through internal acoustic meatus
d. Cochlea
i. Function = transduce sound waves into action potentials for CN 8
ii. Location = fluid-filled portion of membranous labyrinth in the rostral temporal bone
103
103. Should nasal hamartomas be removed and why?
a. Yes. They are locally expansive and cause compression atrophy of the surrounding bone/nasal turbinates, leading to severe and progressive clinical signs. Additionally, recurrence is rare with removal and the prognosis is good.
104
104. Give five differentials for equine head shaking.
a. Dental disease/jaw pain
b. Otitis media/interna
c. Foreign body
d. Trigeminal nerve inflammation, possibly secondary to latent viral infection (rhinopneumonitis)
e. Photic head shaking (triggered by sunlight)
105
105. What is the mechanism of cisplatin ototoxicity? Is it reversible?
a. Inhibit DNA replication and induces apoptosis in dividing cells via production of excessive reactive oxygen species
b. Reduces endocochlear potential, decreases vestibulocochlear nerve fiber function, decreases outer hair cell function
c. Causes primarily auditory ototoxicity that is irreversible and dose-dependent
106
106. How is proliferative and necrotizing otitis externa usually treated in cats?
a. Tacrolimus 0.1% topical produces improvement within weeks
b. Spontaneous resolution is common by 2 years old
107
107. Which system do gentamicin and amikacin target – auditory or vestibular when causing ototoxicity?
a. Amikacin = auditory only
b. Gentamicin = auditory and vestibular
108
108. What is the mechanism of craniomandibular osteopathy and how is it inherited?
a. Recessive autosomal inheritance in Westies
b. Bilateral osteoproliferative disease affecting the mandible occipital bones, and tympanic bullae
109
109. List five signs of nasopharyngeal polyps in cats.
a. Nasal discharge
b. Stertorous breathing
c. Reverse sneezing/sneezing
d. Unequal air flow from nostrils
e. Secondary otitis media due to blockage of auditory tube
f. Visible polyp from the nares or in the back of the throat
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110. What are the two main sources of deep infection following TECA-LBO?
a. Failure to remove the entire horizontal ear canal
b. Epithelium/debris/hair in the external auditory meatus
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111. What are cholesterol granulomas and how are they treated? How do they occur?
a. Benign, granulomatous lesions characterized by cholesterol clefts within a granulomatous inflammatory matrix, commonly occurring after hemorrhage and drainage obstructions
b. Treatment = surgical excision of inflammatory mass
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112. What are the clinical signs of auricular chondritis?
a. Markedly swollen, curled, painful pinnae with intense erythema – begins unilaterally and progresses bilaterally; systemic inflammation is common
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113. What are the 2 most common neoplasms of the external ear canal?
a. Ceruminous gland adenomas and adenocarcinomas
114
See the image of an ear with the TM removed (looking down the left external canal into the middle ear). Label the parts of the middle ear.
115
What are the bones of the auditory ossicles? What are each of the ossicles attached to? What is the overall function of the ossicles?
The three auditory ossicles, the malleus, incus and stapes, are the bones that transmit and amplify air vibrations from the tympanic membrane to the inner ear.
The malleus is attached to the tympanic membrane, the petrous temporal bone, and the incus.
The incus is suspended between the malleus and the stapes.
The footplate (base) of the stapes is attached to the vestibular (oval) window, which is in direct contact with the perilymph fluid.
The vestibular (oval) window is approximately 18 to 20 times smaller in area than the tympanic membrane
