What is the blood supply to the external ear canal?
great auricular a. longitudinally
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]
What are indications for pinna resection? (5)
- neoplasia- mast cell tumor, SCC, basal cell
- thermal injury
- autoimmune disease
- autoimmune disease/ vasculitis
What instrument is used to cut the ear cartilage?
serrated mayo scissors
What suture material do you use to close a pinna resection?
- 4-0 nonabsorbable monofilament
- nylon, prolene, novafil
How do you close a pinna resection after you resect the skin and cartilage?
continuous pattern to close skin only (don't suture cartilage)
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
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
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
What are indications for lateral ear canal resections? (3)
- chronic recurrent otitis externa
- environmental causes
- failed appropriate medical management
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)
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]
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
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
What are contraindications for a vertical ear canal ablation? (2)
- abnormalities of the horizontal ear canal (masses, hyperplastic tissue, structural anomalies)
- middle ear disease
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
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
What breed is most common to need a TECA and why?
- American cocker spaniel
- prone to proliferative hyperplastic ear disease
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]
TECA is always combined with a _________ because...
lateral bullae osteotomy; the epithelial component of the middle ear so it doesn't abscess
During lateral bullae osteotomy, be sure to avoid...
inner ear structures on the cranio-dorsal aspect of the tympanic cavity
What are potential complications of TECA? (4)
- facial nerve injury
- draining tracts (if you fail to remove all the epithelium from the bullae)
- vestibular injury
What are etiologies of middle ear disease in cats? (4)
- inflammatory polyps (nasopharyngeal polyps that arise from the middle ear)
- foreign body
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)