Derm2- Otitis I

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  1. In dogs, the underlying cause of otitis externa is usually ____________; in cats, it is usually ____________.
    allergic; parasitic
  2. What are the 2 cartilages of the external ear canal?
    • auricular: expands to form pinna, funnel shaped
    • annular: fits within base of auricular, overlaps osseous external auditory meatus, flexibility
  3. How do you avoid Noxon's ridge when performing an otoscopic exam?
    pull pinna towards you and upward
  4. Normal microflora of the ear canal. (5)
    Stap, Micrococcus, beta-Strep, Corynebacterium, Malassezia
  5. What glands are within the external ear canal? (2)
    sebaceous glands, ceruminous glands
  6. What is cerumen?
    emulsion that coats the ear canal from desquamated keratinized epithelial cells and glandular secretions; NORMALLY, removed by epithelial migration
  7. What are the components of the middle ear? (4)
    tympanic membrane, auditory ossicles, tympanic cavity, eustachian tube
  8. Describe the histologic appearance of the tympanic membrane.
    no hairs or glands; outer and inner epithelium with a core of collagen
  9. What are the parts of the tympanic membrane?
    • pars flaccida: dorsal part with vascular bed
    • pars tensa: large ventral portion, through which you can see stria mallearis (malleus)
  10. Usually, the pars flaccida is _________ (shape); if it is __________, it does NOT equal middle ear disease unless the animal is a _________ [breed].
    flat; bulging; cavalier king charles spaniel
  11. Which auditory ossicle is in the oval window?
    stapes
  12. What are the 3 portions of the tympanic cavity?
    epitympanic recess, ventral tympanic cavity, tympanic cavity proper
  13. 3 structures of possible communication b/w tympanic cavity and other structures?
    round window, oval window, eustachian tube
  14. What is the purpose of the eustachian tube?
    to equalize pressure within tympanic cavity; communicates with nasal cavity
  15. What is normal middle ear flora?
    may be sterile, BUT may have yeast, E. coli, Staph, Corynebacterium, Strep (50% cultured were sterile, 50% had organisms)
  16. What is unique about the feline middle ear?
    divided by a septum into 2 separate tympanic cavities that are connected through a foramen b/w septum and petrous bone [dorsolateral and Ventromedial portions]
  17. Why can't we do middle ear flushes in cats like we do in dogs with middle ear disease?
    Rosychuck's ridge blocks our access to the tympanic cavity except for a very small area...high likelihood that you will damage inner ear and cause neurologic disease
  18. What are the components of the inner ear? (5)
    bony labyrinth, vestibule, semicircular canals, cochlea, bony surrounds membranous labyrinth
  19. The cochlea is housed in the __________.
    petrous temporal bone
  20. What are the 3 ducts of the membranous labyrinth?
    • scala vestibuli-superior
    • scala media- medial
    • scala tympani- inferior
  21. What are the membranes of the cochlea? (2)
    • Reissner's membrane (floor of scala vestibuli and roof of scala media)
    • Basilar membrane
  22. What fluids are within the scalae of the cochlea?
    • Perilymph- vestibuli and tympani
    • Endolymph- media
  23. The ___________ is the outer wall of the scalae, and the cochlea is surrounded by the ___________, which contain __(2)__.
    spiral ligament; stria vascularis; blood vessels and endolymph
  24. What are the components of the organ of Corti? (5)
    tectorial membrane, reticular lamina, hair cells, supporting cells, and basilar membrane
  25. Why do the scala vestibuli have the same fluid as the tympani?
    both have perilymph because they are continuous with one another (when you unroll the cochlea, they are connected at the tip)
  26. What are the actual receptors for hearing?
    IHC (inner hair cells)
  27. What is the role of the outer hair cells?
    important role in adjusting the tuning an sensitivity of inner hair cells (which are the receptors for hearing)
  28. What part of the inner ear is most susceptible to damage?
    outer hair cells
  29. What information do we encode form the auditory system? What is each determined by? (3)
    • intensity: determined by rate of action potentials firing
    • frequency: determined by part of Organ of Corti that is stimulated
    • location: determined by higher central auditory nervous centers comparing sounds from both ears
  30. The ________ connects the cochlea with the brainstem to relay information about intensity, frequency, and timing of sound; it is part of ___________.
    auditory nerve; CN VIII (vestibular nerve)
  31. Describe the course of the auditory nerve.
    courses from the cochlea through a small canal in petrous temporal bone to the internal auditory meatus
  32. Ascending tract of the cochlea is ____________; descending tract is the ____________, which ends at the __________.
    scala vestibuli; scala tympani; round window
  33. Why is the vibration of the stapes able to displace/send vibrations through the perilymph?
    because the round window compensates and bows out when the stapes vibrates against the oval window [not a static, completely enclosed bony system, therefore this is possible]
  34. Factors that facilitate inflammation by permitting alteration of normal microenvironment and allow estbalishment of secondary infection.
    predisposing factors
  35. Predisposing factors for otitis externa.
    • ear canal conformation: stenotic ear canals, hair in horizontal ear canal (not recommended to remove), pendulous pinnae
    • excessive moisture: swimmer's ear, humid climate
    • treatment effects: trauma from cotton swabs, irritant antiseptic
  36. Why do stenotic ear canals predispose to otitis?
    overgrowth of bacteria and yeast, inhibits proper cleaning of ear
  37. How does hair in ear canal predispose to otitis? How is it managed?
    impairs ventilation and clearance; routine removal of hair NOT recommended
  38. How do pendulous pinnae predispose to otitis?
    restrict airflow
  39. How does moisture predispose to otitis? (3)
    maceration of stratum corneum, secondary infection, swimming/bathing
  40. What are common treatment errors that cause otitis externa? (4)
    cotton swabs to clean ear (abrasive), plucking of hair, irritant ear cleaning solution, improper topical antibiotic usage
  41. Conditions or disorders that initiate the inflammatory process.
    primary causes of otitis externa
  42. Most common parasitic cause of otitis externa.
    Otodectes cynotis- irritate ceruminous glands
  43. How do you diagnose Otodectes?
    cotton swab cytology from ear, mineral oil, visualize mites under microscope
  44. What is the usual presentation of foreign body causing otitis externa?
    acute, unilateral, painful otitis- may cause perforation of tympanic membrane
  45. In the dog, the most common cause of recurrent otitis is ___________.
    allergic diseases [CAFR, atopic dermatitis, +/- contact allergy]
  46. When should contact dermatitis be suspected as a cause of otitis externa?
    if otitis fails to respond or worsen in response to ear meds
  47. What is juvenile cellulitis? (6)
    pups 3-16 wks old, papules, pustules, purulent otitis externa,  submandibular lymphadenopathy, unknown etiology
  48. Endocrine disorders that commonly lead to otitis externa. (2)
    hypothyroidism, hyperadrenocorticism
  49. Autoimmune disorders that can lead to otitis externa. (2)
    pemphigus foliacieus, lupus erythematous
  50. What masses can cause otitis externa? (5)
    ceruminous gland adenoma, adenocarcinoma, SCC, nasopharyngeal polyps (feline), inflammatory aural polyps (dogs- rare)
  51. 3 most common causes of otitis externa in cats.
    Otodectes, polyp, allergic disease
  52. Factors that sustain and aggravate the inflammatory process and prevent resolution.
    perpetuating factors
  53. Perpetuating factors of otitis externa. (4)
    • bacteria [cocci- STAPH PSEDU, rods- PSEUDOMONAS AERUGINOSA]
    • yeast [Malassezia]
    • progressive pathologic changes (edema, stenosis, hyperplasia, fibrosis, calcification)
    • otitis media (rupture of tympanic membrane or through eustachian tube)
  54. When looking at cytology from an ear canal, what bacteria are considered abnormal?
    RODS are always abnormal; >4 cocci/OIF (same for yeast)
  55. Describe progressive pathologic changes of the external ear canal (due to chronic ear infections). (6)
    thickening, stenosis of lumen, edema, epidermal hyperplasia, fibrosis, calcification
  56. How are progressive pathologic changes of the external ear canal treated?
    total ear canal ablation and bulla osteotomy
  57. Can you rule out otitis media by an intact tympanic membrane?
    no, can heal over and act as an abscess that leaks
  58. Most common cause of otitis media.
    bacteria (Staph pseud, Pseudomonas aeruginosa)
  59. Primary secretory otitis media occurs in ____________; clinical signs include... (5)
    cavalier king charles spaniel; head/neck scratching, neurologic signs, hearing loss, intact tympanic membrane, mucoid exudate
  60. How do you dx PSOM?
    Dx by bulging pars flaccida in any cavalier; cannot rule out in absence of bulging pars flaccida—> go to radiographs
  61. What is the etiology of PSOM?
    dysfunctional eustachian tube--> build up of pressure in middle ear
  62. How do you treat PSOM?
    myringotomy (middle ear flushing) draining middle ear; will probably recur and need to be re-treated (b/c you haven't fixed the dysfunctional eustachian tube)
  63. Clinical signs of otitis media. (5)
    recurrent otitis externa, +/- d/c from ear canal,+/- rubbing ears, +/- head shaking and pain, +/- neuro signs
  64. Clinical signs of otitis interna. (4)
    horizontal nystagmus, head tilt, falling to affected side, asymmetric ataxia
  65. What is the best diagnostic for identification of yeast in the ears?
    cytology
  66. What do we use otic cytology for? (4)
    number/type of organisms, inflammatory cells, other (neoplastic) cells, identify yeast
  67. When do we use bacterial cultures for otitis? (3)
    chronic recurrent of unresponsive cases, numerous rods (Pseudomonas aeruginosa) on cytology, concurrent otitis media suspected
  68. Do __________ to determine if you need to submit ___________.
    cytology; bacterial culture and susceptibility
  69. What does the bacterial culture and susceptibility result tell you? (4)
    what the bacteria is, what antibiotics (I/R) will NOT work systemically, does not guarantee S drugs will work, may still use R/I drugs topically (b/c topical is given 100-1000 times higher conc than oral/systemic)
  70. How do look for parasites in the ears?
    sample with mineral oil on slide, lower condenser, low power
  71. You suspect otitis media...how do you proceed?
    radiography to visualize the bony integrity of the tympanic bullae and soft tissue changes in the ear [NORMAL FINDINGS ON RADIOGRAPHY DO NOT RULE OUT OTITIS MEDIA]
  72. What views should you obtain on normal radiography when evaluating the tympanic bullae? (4)
    dorsoventral, right and left lateral oblique (to prevent superimposition of bullae), rostroventral-caudodorsal (open mouth view)
  73. What is an important aspect of imaging when diagnosing otitis media?
    negative does NOT rule out, but abnormalities definitely rule it in
  74. What is a downside to MRI when diagnosing otitis media?
    you can't tell this different b/w air and bone....tympanic bullae is bone (this is why CT is better for this purpose)
  75. What are the general principals of treating otitis? (4)
    clean the ear, topical/systemic glucocorticoids if hyperplasic/ ulcerated, treat underlying primary disease, choose appropriate antibiotics
  76. What do we base our choice of topical therapy on? (3)
    otic exam, cytology, and culture results
  77. What should you NOT use in patients with otits media?
    NO OINTMENTS [versus solutions and lotions, which will be absorbed through the epithelium; ointments will be almost impossible to remove from the middle ear]
  78. How do you rule out otitis media?
    myringotomy
  79. Describe in hospital otic flushing. (6)
    general anesthesia w/ ET tube, +/-radiographic imaging, cytology/culture sample BEFORE FLUSH, ten-minute soak with cerumenolytic agent, flush using warm saline and bulb syringe, final flush with saline through catheter
  80. What is the only cerumenolytic agent that has been proven to NOT be ototoxic? What are the implications of using other agent?
    Cerumene; get them out!!! flush thoroughly
  81. Describe the purpose/indication of myringotomy. (4)
    samples, remove exudates, drain middle ear, treat middle ear
  82. Where is the incision made for myringotomy?
    caudoventral quadrant [to avoid ossicles, round and oval windows]
  83. What are possible complications with in hospital otic flushing? (4)
    facial nerve paralysis, Horner's syndrome, vestibular disturbances, deafness
  84. How long does it take for the tympanic membrane to heal after myringotomy?
    21-35 days

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Author:
Mawad
ID:
316441
Filename:
Derm2- Otitis I
Updated:
2016-03-01 14:54:07
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vetmed derm2
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vetmed derm2
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