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What is the blood supply to the external ear canal?
great auricular a. longitudinally
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Where does the facial n. run and why is this important?
- arises from the stylomastoid foramen caudal to the external acoustic meatus [lateral and ventral to the horizontal canal]
- important because it can be damaged during surgery to the external ear canal [TECA]
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What are indications for pinna resection? (5)
- neoplasia- mast cell tumor, SCC, basal cell
- thermal injury
- autoimmune disease
- autoimmune disease/ vasculitis
- trauma
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What instrument is used to cut the ear cartilage?
serrated mayo scissors
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What suture material do you use to close a pinna resection?
- 4-0 nonabsorbable monofilament
- nylon, prolene, novafil
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How do you close a pinna resection after you resect the skin and cartilage?
continuous pattern to close skin only (don't suture cartilage)
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Describe the formation of aural hematomas?
- accumulation of blood or serosanginous fluid b/w the layers of cartilage forming the pinna, usually on the concave surface
- usually due to head shaking d/t otitis externa, dermatitis, allergic skin disease, or trauma
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Describe the most commonly used surgical procedure for treating aural hematoma.
- establish continuous drainage by making an incision on the concave surface of the pinna and drain the hematoma
- create a small gap for wound drainage
- then eliminate potential space b/w the cartilage layers with mattress sutures parallel to incision and compression bandages for 2-3 weeks
- TREAT UNDERLYING CAUSE
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Describe the less commonly used skin punch technique for treating aural hematoma.
- using a skin punch biopsy, make several punch biopsy sites over the inner surface of the pinna
- using 4-0 nonabsorbable monofilament, tack the adjacent skin to the cartilage at each biopsy site
- will have a more cosmetic effect
- does not require bandaging
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What are indications for lateral ear canal resections? (3)
- chronic recurrent otitis externa
- environmental causes
- failed appropriate medical management
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What are contraindications for lateral ear canal resection? (3)
- evidence of middle ear disease
- mass lesions located on medial wall of vertical or horizontal canal
- evidence of hyperplastic ear diseases (don't do this procedure in American cocker spaniels....will always result in needing TECA)
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What are the goals of lateral ear canal resection?
- improved air and light exposure
- [still requires client compliance to maintain horizontal canal- cleaning, hair trimming]
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What is the result vertical ear canal ablation?
complete removal of all aspects of the vertical ear canal and direct opening of the horizontal canal to the skin
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What are indications for a vertical ear canal ablation? (3)
- neoplasia affecting only the vertical canal
- congenital malformation or stenosis of the vertical canal only
- trauma
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What are contraindications for a vertical ear canal ablation? (2)
- abnormalities of the horizontal ear canal (masses, hyperplastic tissue, structural anomalies)
- middle ear disease
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What's the difference between a lateral and vertical ear canal ablation?
- Lateral: leave vertical canal, just open it up more; used for chronic otitis externa without end-stage changes
- Vertical: actually remove entire vertical canal; used for neoplasia, congenital malformation, trauma
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What are indications for TECA? (4)
- salvage procedure for an end stage ear
- failure to respond to appropriate medical therapy
- obstruction of external ear canal (hyperplasia, mineralization, stenosis, neoplasia)
- chronic pain/ discomfort
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What breed is most common to need a TECA and why?
- American cocker spaniel
- prone to proliferative hyperplastic ear disease
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What is the result of TECA?
removal of the complete external ear canal to external auditory meatus, leaving the pinna [requires opening the petrous temporal bone]
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TECA is always combined with a _________ because...
lateral bullae osteotomy; the epithelial component of the middle ear so it doesn't abscess
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During lateral bullae osteotomy, be sure to avoid...
inner ear structures on the cranio-dorsal aspect of the tympanic cavity
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What are potential complications of TECA? (4)
- facial nerve injury
- dehiscence
- draining tracts (if you fail to remove all the epithelium from the bullae)
- vestibular injury
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What are etiologies of middle ear disease in cats? (4)
- inflammatory polyps (nasopharyngeal polyps that arise from the middle ear)
- infection
- neoplasia
- foreign body
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What approach to the bullae do you do in dogs versus cats?
- Dogs- lateral bullae osteotomy (b/c you're almost always removing the ear canal as well)
- Cats- ventral bullae osteotomy (b/c of bony septum and b/ you are leaving the ear canal intact)
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