drraythe's version from 2016-04-29 14:47

etiology of otitis, anatomy

Question Answer
what is the external canal's lining like? how does the external canal clean itself?it has a epidermis and dermis and it goes through a normal epithelial cell cycle. It also has Sebaceous glands & ceruminous glands which are basically modified apocrine glands. EPITHELIAL MIGRATION is the primary cleansing mechanism
what stuff is in the middle ear?Tympanic membrane, ossicles, Tympanic cavity, facial nn and sympathetic chain
what are the two portions of the inner ear?vestibular and cochlear
three classifications of otitis by area of involvement?otitis externa, media, or interna
3 classifications of otitis by primary etiology?parasitics, allergic, seborrheic
3 classifications of otitis by appearance?ulcerative, proliferative, purulent
purulent otitis is ___ until proven otherwise in her book, she saidpseudomonas
etiology of otitis is the 3 Ps--(1) Predisposing factors (sets up ear for inflammation) (2) Primary factors (initiate inflammation) (3) perpetuating factors (keep inflammatory process ongoing and prevent resolution) ........there are also secondary factors (This is your bact and yeast basically)
what kinda conformations can predispose to otitis? which breeds are particularly at risk?pricked up ears versus floppy ears- GSD ears predisposed bc ears stick up and cause long ear canals which are sloping....long and sloping predispose. Then COCKER SPANIEL are predisposed bc long floppy ears- not a lot of air getting in and out of canals, and also high number of ceruminous glands which can predispose them
what are some things that cause Obstructive ear disease which can be a predisposing cause of otitis?Excessive hair growth (impair airflow, debris gets stuck in there), Tumours, inflammatory polyps in cats, ceruminous gland cysts (also cats)
a predisposing factor to otitis is Maceration....what are the kinda activities which can cause maceration?ie maceration= wet ears break down easily, so swimming and bathing can predispose
how can environment predispose to otitis?heat and humidity
2 iatrogenic things which can predispose to otitis?(1) traumatic prophylactic hair removal (2) traumatic ear cleaning (DONT USE QTIPS.)
3 things which can cause immunodeficiency which can predispose to otitis?FeLV, FIV, Candidiasis
1* factors--> what parasitic dzs causes otitis? (who is prone)(1) otodectes cyanotis (ear mites) (puppies, kittens, and adult cats seem predisposed) (2) Demodex (3) Trombicula (harvest mites) and lice might affect ear flap
1* factors--> 2 allergic dzs which can cause otitis?(1) atopic dermatitis- SUPER COMMON in this, sometimes otitis is only CS of it! (5% only CS), (in 75-100% of cases) (2) food allergy (in 80% of the cases) otitis often the only CS in this problem too (20% of the time!)
primary factors which can cause otitis are...parasitic dzs, allergic dzs, FBs, seborrhea, autoimmune dzs, juvenile pyoderma (puppy strangles), or any other generalized skin dz
perpetuating factors--> explain the progressive path. changes that happeninflammation--> stenosis of canal--> fibrosis of dermis and SQ--> calcification of the cartilage
what are some of the progressive path changes that you can observe from otitis?epidermal hyperplasia, hyperkeratosis, hyperpigmentation
perpetuating factors--> otitis media perpetuates otitis externa AND might cause what big problem?ruptured tympanum
perpetuating factors--> Cholesteatoma---> what the hell is this/ when does this happenmight form in cases of CHRONIC otitis MEDIA. it is GRANULATION TISSUE with a thickened tympanic membrane which forms an EPIDERMOID CYST
what are the three secondary factors of otitits?(1) Bact: g+ and g- (2) yeasts: Malassezia, Candida albicans (3) Allergic contact dermatitis: reaction to topical ear Rx (neomycin, propylene glycol)

clinical approach to otitis

Question Answer
what are the 4 steps in order you must do(1) Thorough history & complete P/E (2) otoscopic exam (3) diagnostics (4) establish diagnosis
what are the 3 main kinds of diagnostics you do for otitis?CYTOLOGY, +/- C/S, +/- diagnostic imaging
in order to establish dx you must remember what factors??3P's and the 2-- predisposing factors, primary factors, perpetuating factors, secondary factors
why is it important to always do a full PE with otitis?otitis often a manifestation of a more generalized dz
what kinda stuff should you look for on your superficial otic exam?eval type of pinnae, and potential for circulation of air, look at degree of erythema of pinnae and vert canal
what are the main clinical signs of otitis EXTERNA?head shaking and scratching at ear, erythema of visible portion of ear canal, discharge/exudate
what should you do during the otoscopic exam?*good restraint or sedation! examine diameter of vertical and horizontal ear canals, note nature of any discharge, look for mites or FBs, check integrity of tympanic membrane
CYTOLOGICAL EXAM--> how many samples should you get, and from where? why do you need to samples? Get 2 samples from HORIZONTAL canal- (1) Dry- stain with diff quick to see bact/yeast (2) mineral oil to look for otodectes/ other parasites
decision to tx with topical Rx will depend on...microbial load and CS
bacterial C/S is usually not done on 1st exam UNLESS?cytology reveals presence of rods
indications for C/S? (2)(1) chronic, recurrent cases (2) cases which fail to respond to initial tx
when would you wanna do some diagnostic imaging? what does it help you see? what kinda DI can you do?indicated in CHRONIC cases of otitis. aids in ID of osseous changes, fluid in tympanic bulla, and masses. Can do rads, CT, and MRI

Approach to therapy

Question Answer
5 main steps?(1) initial ear cleaning (2) drug therapy (as appropriate) (3) follow up (4) treatment of 1* perpetuating factors (5) long-term prevention
what are the 4 possible drug therapies, based on what the problem is?antimicrobial, antifungal, anti inflammatory, anti-parasitic
if the canal is too narrowed to pre-clean effectively, what might you have to do?may need to use parenteral steroids to open up canal before initiating therapy
If you are unsure of if the tympanic membrane is ruptured, do what?when in doubt, assume it is ruptured, avoid ototoxic agents
how will initial ear cleaning technique vary between in clinic and at home?IN CLINIC: deep ear flush (bulb syringe, video otoscope). AT HOME: manual cleaning with a cotton swab, and FOR THE VERT CANAL AND PINNAE ONLY, cotton tipped applicators
if there is a RUPTURED tympanum, what 3 cleansing agents can you choose from for your initial cleaningwater, saline, or chlorhexidine at 0.2% (IT IS OTOTOXIC AT 2%)
When is a cerumolytic otic cleaning preparation indicated? what do these kinda cleaners do? WHAT PRECAUTIONS should you take? what are some examples?indicated in cases of INC EXUDATE! itll soften and emulsify waxy ceruminous debris. Examples include: propylene glycol (most common), glycerine, SQUALENE is SAFE in ruptured TM, carbamide peroxide** and dioctyl sodium succinate** (**=These cleaners are OTOTOXOIC so flush well after a period of contact)
which kinda cleaning agent is Propylene glycol?cerumolytic
*what should you know about squalene as a cleaning agent?it is a cerumolytic which is SAFE TO USE IN RUPTURED TYMPANIC MEMBRANES
which two ceruminolytic agents are OTOTOXIC and flushing after use is necessary?carbamide peroxide** and dioctyl sodium succinate**
when are cleaning/drying cleaning agents indicated? WHO is this useful in? what are some examples of these? (what can you combine these with?)indicated if there is a little exudate- helps prevent maceration so is good to use with swimmers. Exs include: lactic acid, Salicylic acid, Aluminium acetate, boric acids. (can combine with ceruminolytics)
*what is probably the most important step in managing ear dz?thorough, gentle, atraumatic flushing
before you can apply medicine, the ear canal totally clean
what can you do to remove big stubborn pieces of debris from the ear?can be removed with forceps or an ear loop
Parasiticidal therapy--> what are some topical agents you can use? what else aside from these can help?thiabendazole, pyrethrins, rotenone & carbaryl. newer spot-on topicals for systemic use (like revolution) are also generally effective
what are the effective topical antibacterial agents?gentamycin, neomycin, polymixinB, colistin, chloramphenicol and fluoroquinolones (ie.Baytril®)
what can you do with the pH to help with bact infection?Agents which LOWER the pH might be useful (acetic acid, others)
what can Monosaccherides help with?dec adherence of BACTERIA
what is TrizEDTA helpful in treating? how does it help?Help with BACTERIAL infection, bc significantly enhances the effectiveness of antibiotics! It inc bacterial susceptibility also. This synergism is not only with abx, but also with chlorhexidine.
when are the two occasions that SYSTEMIC antibacterials are used?(1) otitis media (2) ruptured tympanic membrane. (might also be helpful in chronic cases)
what are the systemic abx you can use?(remember, for OM or ruptured TM) **Fluoroquinolones are especially helpful, also can use Trimethoprim/sulphur, clindamycin, cephalexin, amoxacillin/clavulanicacid
If you are going to use systemic/topical abx for a chronic case, what should you do?should guide therapy with C/S
When would you use antifungal agents? what are the topical agents you can use?use when prolif of yeast. topical agents include: miconazole, nystatin, thiabendazole
what is often in trivalent otic preparations?antibacterial + antifungal + anti-inflammatory
when would you want to use SYSTEMIC antifungals? which ones?helpful in severe cases, ESP where there is middle ear involvement. Can use ketoconazole or itraconazole
Anti-inflammatory agents--> which ones do you use? when do you do local versus systemic?topicals indicated in most cases, bc reducing inflammation and exudate makes environment less hospitable for microorganisms. Systemic steroids/locally injected are indicated where there is SEVERE HYPERTROPHY of the ear canal
which abx are DANGEROUS for use in ruptured tympanum, which are safe to use?AMINOGLYCOSIDES ARE OTOTOXIC!! Fluoroquinolones are safe
how can you inc efficacy of fluoroquinolones in the ear?ad EDTA- it "pokes holes" in bact and more abx will get inside
what should you keep in mind with C/S?(1) since you can reach high conc in the ear, might be able to still use abx which the bugs were shown to be resistant to (2) C/S might show non-repeatable results, with differing isolates in outer vs middle ear
what is the prog of a ruptured tympanum?good! healing to be expected in 15-30d
what is a condition which might arise from clinical signs associated with otitis?anything with lots of head shaking/ear scratching predisposes to aural hematomas (some evidence of an immunological abnormality in some cases)
if you see an aural hematoma, you should ALWAYS...ALWAYS EVAL FOR UNDERLYING OTITIS!
how do you tx aural hematoma?tx with tapering dose of systemic corticosteroids- sx repair is falling out of favor.