Surgery of the ear Flashcards
The inner ear is made up of two main parts
membranous and bony labyrinth, functions for hearing and balance.
The middle ear is formed by
the tympanic cavity, connects to the
pharynx via the auditory tube.
The external ear is formed by
the auditory meatus and a short canal.
- The pinna
- The facial nerve exits the stylomastoid foramen caudal to the ear, courses ventral to the horizontal canal close to the middle ear.
for surgery of the canine ear, Several landmarks at the base of the ear:
- The pinna varies greatly in size and shape
- Cartilage interposed between two skin surfaces
- Main vessels located along the convex surface of the ear
- Main branches of nerves on either surface
the Feline tympanic cavity is divided into
two compartments by a thin, bony septum.
What special structure do feline inner ears have that dogs dont?
the bony septum and Postganglionic sympathetic nerve plexus on a structure known as the promontory (trauma during surgery – Horner syndrome).
TECA-BO stands for
Total Ear Canal Ablation and Bulla Osteotomy
the secretory epithelium of the bulla must be removed before closure otherwise it will continue to secrete and potentially form an abscess later on.
4 signs of Horner’s syndrome
“lazy” eyelid/ptosis
enophthalmos
visible nictitating membrane
miosis of the eye unilaterally
facial nerve palsy affects the facial nerve so is a similar but different condition to horner’s
What are cats prone to after TEC-BO that dogs arent?
horner’s syndrome
Preoperative concerns/questions and diagnostics before ear canal ablation. (9)
- Assessment of the extent & severity of disease (also unilateral/bilateral?)
- Otoscopic examination
- Diagnostic imaging (X-R, CT, MRI)
- Any abnormalities should be noted before surgery to avoid confusion with problems caused by intraoperative trauma.
- Thickening, calcification of the ear canal – irreversible inflammatory disease.
- Sharp pain response on palpation – middle ear infection?
- Head tilt – severe pain/otitis media/otitis interna?
- Neurologic deficiencies/vestibular dysfunction – otitis interna?
- Facial nerve deficiencies - facial nerve embedded in the horizontal canal/
serious concurrent middle ear disease?
Hearing and TEC-BO
many dogs are already deaf before the procedure but not all.
some reports that dogs may still retain hearing capability after ear canal ablation.
Anesthetic considerations for ear canal ablation. (4)
- Preoperative bloodwork (HCT, TP; electrolytes, BUN, Crea in older)
- Ear surgery often very painful (TECA, canal resections)
- Hydromorphone and morphine may be preferred over butorphanol and buprenorphine.
- Local anesthetics: bupivacaine hydrochloride (open surgical site).
PostOP considerations for ear canal ablation. (3)
- Postoperative constant rate infusions
(e.g. FLK) can be considered. - Elizabethan collar postoperatively
- Normal wound care, sutures removed in
10-14 days
Antibiotic therapy after ear canal ablation.
- Preoperative antibiotics recommended.
- Severe infection treated with systemic and/or topical antibiotics for several weeks before surgery is often performed.
- Cultures of deep tissues taken during surgery from deeper sites are often more useful than preoperative cultures – initial treatment is empirical.
Indications for TECA. (7)
(you should remember min. half of these for the exam)
= Total ear canal ablation
- Chronic otitis media
(non-responsive to medical management) - Severe calcification of the ear cartilage
- Severe epithelial hyperplasia extends beyond the pinna or vertical ear canal.
- Severely stenotic ear canals
- Neoplasia of the ear canal
- Nasopharyngeal/inflammatory polyps (preferably ventral bulla osteotomy) located in the nasopharynx, auditory tube, tympanic cavity, or all three.
- In case lateral ear resection has failed
Materials and special instruments
used in TECA. (5)
- Electrocautery useful (numerous small vessels)
- Small curettes
- Rongeurs of various sizes (pictured)
- Retractors to be used quite superficially
- Culture swabs (both aerobic and anaerobic)
Surgical technique for TECA. (9)
- Animal in lateral recumbency, head elevated; skin prepared for aseptic surgery
- T-shaped incision, continued around the opening of the vertical ear canal
- Dissection around the vertical canal, continued to the level of the external
acoustic meatus - Excision of the horizontal canal attachment to the acoustic meatus (histologic examination?)
- Deep cultures around or just inside the external acoustic meatus obtained
- Careful removal of secretory tissue adherent to the rim of the meatus
- (Lateral bulla osteotomy performed if needed)
- Placement of a Penrose drain if desired (F in image)
- The subcutaneous tissue and skin closed (2 layers)
Modified TECA is
single-pedicle advancement flap at the base of the pinna
May facilitate upright ear carriage (better cosmetic result).
Lateral bulla osteotomy (BO) involves…
the exposure of the middle ear (tympanic cavity) in order to remove debris and tissue, exudate, secretory epithelium.
- Offers less exposure to the tympanic
cavity than a ventral BO. - Preferred in conjunction with TECA
(no need to reposition the patient).
Lateral bulla osteotomy technique (6)
- Tissue bluntly dissected from the lateral aspect of the bulla
- Damaging the external carotid artery and the maxillary vein avoided (they travel just ventral to the bulla)
- The caudal aspect of the middle ear canal exposed by a rongeur
- Curette used to remove infected material (curetting in the rostral (dorsal) or rostromedial area of the tympanic cavity avoided so as not to damage the auditory ossicles or inner ear structures).
- Removal of remaining debris by gently! irrigating the cavity with saline. (flushing too hard can cause vestibular syndrome)
- The subcutaneous tissue and skin closed
Describe Ventral bulla osteotomy (3)
- Performed alone or in conjunction with lateral ear resection
- The technique of choice in cats
with inflammatory polyps - Bilateral procedures can be performed without the need to reposition the patient (place in dorsal recumbancy).
Describe Lateral ear canal resection (4-5)
If you don’t want to remove the entire external ear canal and you don’t need to perform bulla osteotomy - just do lateral ear canal resection. You just remove the entrance/vertical part to the external ear canal, leaving the horizontal part in place.
- Increased drainage, improved ventilation
Indications:
* minimal hyperplasia of the ear canal epithelium
- small neoplasia in the lateral aspect of the vertical canal
- Often not a cure – medical management of the ear likely necessary for the remainder of the animal’s life.
Describe Vertical ear canal ablation
Once again, not removing the entire canal on the vertical part.
- Increased drainage, improved ventilation
Indications:
* diseased vertical canal, normal horizontal canal
- neoplasia in vertical canal
- otitis externa (unresponsive to medical management)
- Often not a cure – medical management of the ear likely necessary for the remainder of the animal’s life but now from a hole in the side instead of the typically part.
Describe Aural hematomas.
- A collection of blood within the cartilage plate of the ear.
- Cause not well understood – appears to be the result of head shaking or scratching at the ear (often underlying problem).
- Initially appear fluid filled, soft, and
fluctuant, but eventually may become
firm and thickened as a result of fibrosis.
Medical management of aural hematomas.
- Needle aspiration (daily?) can be performed, but recurrence likely.
- Use of corticosteroids administered by a variety of routes has been described to treat aural hematomas.
- Corticosteroids directly into the hematoma cavity following drainage
of fluid has successful resolution in over 90% of cases.
Describe Surgical technique for aural hematomas. (6)
- S-shaped incision on the concave surface (exposing the hematoma from end to end)
- Removal of the fibrin clot, irrigation of the cavity
- Placement of 0,75-1 cm sutures (2-0/3-0 monofilament) (parallel to the major vessels)
- Incision not closed (slight gap allows drainage)
- Placement of a light protective bandage over the ear; supporting the ear over the animal’s head (not everyone uses bandages at all tho)
- Removal of the bandage and sutures in 14 to 21 days after scar tissue has formed.
Repair of pinnal defects (cosmetic purpose)
- Small avulsions of the ear margin
– resection of surrounding tissue
to maintain normal contour. - Larger defects – pedicle flap may
be used - Repair should be delayed after
excision of neoplasms until it has been determined that recurrence is unlikely
Describe Neoplasia of the pinna
- Relatively uncommon in dogs and cats.
- Neoplasias may arise from any structure that lines/supports the ear canal.
- Benign/malignant
- Aural tumors tend to be more aggressive in cats than in dogs.
- Any tumor that affects the skin may arise on the pinna
- The most common tumor of the pinna in cats is squamous cell carcinoma (particularly older white cats); metastasis uncommon.
- Others: melanoma, fibrosarcoma, basal cell tumor, fibroma, lymphoma,
histiocytoma, papilloma, mast cell tumor
Suspected pinnal neoplasias must be differentiated from
non-neoplastic lesions such as dermatitis caused by insect bites or immune-mediated lesions.
- Preoperative cytologic studies may help determine whether radical resection is necessary when neoplasia is suspected
- Suspicious lesions should be biopsied (or removed?)
Surgical treatment of pinnal neoplasia.
- Removal of the neoplasm with a wide margin of normal surrounding skin
- May require pinnectomy +/- (vertical) ear canal ablation
- Prognosis variable
- Amputation of the pinna for squamous cell carcinoma of the ear margin may be curative
Surgical technique for pinnal neoplasia.
- Removal of the affected portion of the ear
- Suturing the remaining skin over the
exposed cartilage - If aggressive surgical therapy cannot provide clean margins – adjunctive therapy should be considered (radiation)
Wounds after excising small tumors from the center of the pinna can:
* be closed primarily
* be left open to heal by secondary intention under a bandage
* be closed with the help of skin flaps
