122.External ear and pinna Flashcards
name for the auricular cartilage of the pinnae
scaphecovered by skin on both sidesanthelix is medial cartilage protuberence (opposite is tragus–lateral)caudal–antitragus, rostral–helix
blood supply to the pinnae
caudal auricular artery (branch off of external carotid artery)
cartilage of the ear canal (3)
- scutiform cartilage: detached, cranially2. auricular cartilage of the vertical ear canal: telescopes around annular cartilage3. annular cartilage of the horizontal ear canal: telescopes into the auricular cartilage
lining of ear canal
stratified squamous epithelium hair folliclesadnexal structures ceruminous glands (deeper), sebaceous glands (superficial)
innervation and blood supply of the external ear
innervation: FACIAL VII (MOTOR) exits stylomastoid foramen caudodorsally and crossed the central aspect of the horizontal ear canal; VAGUS X (sensory); VESTIBULOCOCHLEAR VIII within bullaeblood supply: great auricular artery (br of external carotid artery); external carotid artery and maxillary vein lie ventral to the bullae, rostral to the bullae is the retroglenoid vein; medial to bullae is internal carotid artery
diseases of the ear pinnae
—aural hematoma –laceration–neoplasia (actinic keratitis, SCC, Hemangioma/HSA, MCT, basal cell tumors, sebaceous adenomas/AdCa, histiocytomas–resolve spontaenously)–infxn/inflammatory dz
actinic keratitis and SCC of the ear pinnae
actinic keratitis–premalignant change, poorly pigmented skin exposed to UV B lightSCC–low metastatic rate; locally invasive; WHITE CATS 13.4 times greater riskTx: partial pinnectomy, total pinnectomy +/- ear canal ablation, photodynamic therapy, if small–cryotx, laser ablation+/- radiation, chemoMST with excision SCC 800 days!
hemangioma and hemangiosarcoma of the ear pinnae
UV B light inducedhemangiomas: benign, blue tinged, dermal raised hairless (rule out: ceruminous carcinoma/adenoma from ear canal)HSA: malignant, fast growing, fast met
what is the most frequent feline cutaneous neoplasm that can also effect the ear pinnae
basal cell tumorscarcinomas that are slow growing and well demarcated, hyper pigmented nodulesonly few mm margin needed
MCT of the ear pinnae dogs vs cats
account for 60% of cutaneous MCT of the headcats—well circumscribed, discrete raised tumors, local excision could be curative (incomplete margins were not associated with higher recurrence)dogs—42% met to LN (may be more aggressive in ear than elsewhere), wide 2cm excision needed with pinnectomy +/- radiation, +/- chemo if grade 3
causes for otitis extern and media
- primary: parasites (ear mite 50% cats), FB, hypersensitivities, keratin disorders, IM dz, endocrine dz (change cerumen/keratin)2. predisposing: incr risk but not responsible on their own—anatomic considerations (pendulous, narrow, excessive hair, excessive cerumen); ear moisture; tumor/poly obstructing drainage3. perpetuating: allow the dz to continue—bacT overgrowth of commensals/polymicrobial; rupture of tympanic bullae (18%)
most common pathogen isolated in ears
Staph intermedius 70%others include Strep, Pseudomonasusually both ears can be affected with different bacT (culture BOTH)
neoplasia of the external ear canal
most malignant and epithelial (60% dogs 88% cats)ddx: ceruminous adenocarcinoma/ adenoma, SCC, sebaceous adenoma/adenocarcinoma, anaplastic carcinoma, ST sarcoma, melanoma, basal cell tumors, polypsCocker spanielceruminous adenocarcinoma accounts for most tumors of external ear canal (dog, cat)CT
methods to treat traumatize avulsion of the annular vs auricular cartilage
—primary repair with caudal approach to the ear—TECA-LBO
congenital/developmental disease of the external ear canal
external auditory canal atresia (blind pouch)—salvage pull through of remaining canal to skin—TECA–LBO
Para aural abscessation
CAUSES: extension of otitis externa, animal bites/perforation/infection, penetrating FB, traumatic separation of cartilages, neoplasiaMOST COMMON CAUSE : incomplete bullae lining removal after LBO < 10%
diagnostics for externa ear disease workup
–PE, ortho, neuro–sedated otoscopic examination–sedated oral exam (nasopharynx eval!)–CBC, Chem, UA +/- immune mediate, endocrine dz testing–STT if indicated (facial nerve paralysis) –skin scraping, skin allergy testing if indicated–deep ear swab cytology AU +/- myringotomy–deep ear cultures AU +/-myringotomy–Skull rads–contrast fistulography/canalography(detects rpture in 14% that appeared intact on otoscopy)–thoracic rads if staging for neoplasia—LN FNA if staging for neoplasia–Advanced imaging (CT) preferred–FNA –Biopsy +/- impression smear
T/Fidentfying a normal intact tympanic membrane does NTO rule out otitis media
TRUEit can be intact in up to 70% of ears with proven otitis media(only 18% are ruptured)
culture from bullae vs canal
differ in 90% of cases
methods for auricular hematoma treatment
—percutaneous drainage and topical GCC injection (successful in 90%; may need multiple)—teat canal drainage—closed suction tube drainage—surgical drainage + full thickness parallel sutures**–CO2 laser drainage and ablation+/- bandageif left untreated with fibrosis and contract
surgical options for the external ear canal
—lateral vertical wall resection (drain board): reversible diseases or small tumor on vertical lateral wall, allows drainage and air,–vertical canal ablation: extensive disease/irreversible of vertical canal but NOT horizontal; not often performed—vertical canal incision for middle ear polyp that extend into vertical ear canal (does not allow for debridement of middle ear)—TECA—LBO: extensive benign disease, neoplasia, severe trauma; concurrent derm disease 60-80%
complications associated with TECA–LBO
- facial nerve damage (50%—25% permanent, 25% temporary and resolves 2-4 weeks, maybe longer in cats): secondary corneal ulcers if not lubed!2. horners (damage to sympathetic fibers)–post ganglionic in middle ear; cats> dogs3. vestibular dz/nystagmus (CATS 60%)4. pinnal necrosis (incise to far distal on medial aspect, damage to caudal auricular artery branches)5. chronic fistula (if incomplete removal of tympanic lining) <3%8. decreased auditory function (though owners think hear better without pain/stenotic/proliferative changes)9. change in pinnal cosmesis10. cholesteatoma (2 reports brachy breed post TECA LBO mo-yrs)
vasculature to avoid during LBO
rostral—retroglenoid veinventral—external carotid artery and maxillary veinmedially–internal carotid artery
tympanic bullae anatomy and curretage
extend osteotomy ventrolaterally (caution with neurovascular structures)avoid aggressive curettage dorsally near ossicles and promontory to decrease vestibular deficitsdogs: single bullae compartmentcats: two compartments 1. ventral (LARGE) 2. rostral (small) separated by thin boney shelf
recommended Ab dose therapy duration
4-6 weeks or longer depending on the culture and/or extensiveness of infectionbase on culture/sensitivity and bacT isolated
ossicles of the ear
malleusstapesincus
T/FNo difference in the incidence of immediate or long term complications in dogs with wounds closed primarily vs those with indwelling passive penrose drains
TRUE no diff
use of lidocaine wound soaker catheter vs CRI opioid in post op TECA patients
no diff in painless sedation with lidocaine CRIwell toleratedinfusion of lidocaine or sterile saline results in 40% wound complications (fluid accumulation, drainage, edema)
lateral wall resection vs TECA-LBO for treatment success of otitis externa
lateral wall resection: poor in 87%TECA-LBO: improved 60-90%
px ceruminous adenocarcinoma treated with TECA LBO
DOGSif confined to ear canal: MST 30 moif extensive canal, bullae involvement: 5-6 moCATS MST 42 mo with recurrence 25%neuro signs preoperatively, SCC, anaplastic carcinoma of ear canal are poor prognostic indicators in cats
MST SCC pinna
wide excision MST 800dphotodynamic therapy small tumors 100% remission, regrowth 18 monthscryotherapy recurrence 73% in 180 days
