Ear canal ablation, more than palliation (Proceedings)

Disease of the ears is very common in both dogs and cats. Infectious, parasitic, neoplastic, immune related, allergic disease, foreign bodies and trauma may affect the ears. Infectious disease caused by bacteria, fungi, or yeast is very common as well as ear mite infestation. Chronic infectious disease often causes hypertrophy/hyperplasia of skin surrounding the external auditory meatus and within the ear canal. Neoplastic disease such as polyps or ceruminous gland carcinomas are also relatively common in both dogs and cats. Autoimmune disease and allergies (atopy/food hypersensitivity, drug) also may affect the ears.

Medical work-up of ear disease includes complete otoscopic examination and cleaning which usually requires anesthesia of the patient. Cytologic examination and cultures of otic specimens (especially if chronic) are recommended although the value of aerobic culture is questionable. Skin testing, hypoallergenic diets, biopsies and radiographs are indicated in individual cases of ear disease to rule in/out disease entities. Skull/Bullae radiographs or CT imaging are strongly recommended in those animals with suspected neoplastic disease to determine if possible whether the disease is confined to the ear canal or has invaded surrounding soft tissue or the bulla.

Surgical treatment of ear disease involving the vertical and horizontal ear canals have been regarded by some veterinarians as "salvage" or palliative procedures. Lateral ear canal resection, vertical ear canal ablation, and total ear canal ablation have been described as satisfactory surgical treatment modalities for ear disease depending upon the chronicity/severity of disease, the inciting cause, and the anatomic portion of the canal affected. Appropriate and careful case selection for each of these procedures is regarded as critical in ensuring the most positive outcome for the patient and owner.

Lateral Ear Canal Resection

Lateral ear canal resection has a long history in veterinary surgery. Lacroix and Zepp described this procedure and modifications thereto 50+ years ago. Many veterinarians have been taught this surgical procedure during their education as the surgical procedure of choice for animals with ear disease. The purpose of the procedure is to provide drainage of the horizontal ear canal and to alter the environment of the ear canal thereby allowing easier treatment of ear disease. Gregory and Vasseur reported in 1983 that a high percentage of animals having this surgery performed do not respond in a satisfactory fashion (1). This is most likely due to poor case selection; i.e. performing surgery in an animal with chronic skin changes (hypertrophy/hyperplasia) already present, or performing the surgery in an atopic/food allergy patient without treating the underlying disease. Lateral ear resection is intended to aid in therapy and not cure otic disease. Due to the tertiary nature of our caseload we rarely perform this procedure. It is likely that veterinarians in a primary practice may encounter animals more commonly that may benefit from this surgical procedure.

The animal is placed in lateral recumbency and two parallel skin incisions made from the tragohelicine notch and intertragic notch ventrally approximately 1.5x the length of the vertical canal. The incisions are joined ventrally and the skin reflected dorsally and the subcutaneous tissue and parotid salivary gland reflected from the lateral aspect of the ear canal. Scissors are then positioned within the ear canal to incise the vertical canal cartilage rostroventrally and caudoventrally. Care is taken to keep these cuts of uniform width so that at its base the width is approximately that of the horizontal canal. The resulting drainboard is then sutured to skin with 3-0 non-absorbable suture material. In general, I regard this procedure as a "probably won't hurt" operation but have little faith in its efficacy over-all. Complications are not uncommon and consist of partial or total dehiscence of the sutured drain board. Second intention healing or seconday closure is indicated in those patients.

Comment-It is my sense that many owners in spite of extensive preoperative counseling tend to equate surgery with expectations of a "cure" thus owner disappointment following this procedure is possible. Once again, it is necessary that there be a patent ear canal with minimal change to surrounding skin for this procedure to be effective. IT IS RARE FOR US TO PERFORM THIS SURGERY.

Vertical Ear Canal Resection/Ablation

Vertical ear canal ablation is indicated in those animals that have disease of the vertical auditory canal and a patent horizontal ear canal. This procedure has a relatively low complication rate and preserves the horizontal canal and thus in theory, auditory function. Animals having the procedure usually continue to require treatment of ear disease.

The animal is placed in lateral recumbency and a T-shaped skin incision is made encircling the external auditory canal and extending distally to approximately 1 cm ventral to the junction of the vertical and horizontal ear canals. The vertical canal is dissected as close to the perichondrium as possible to the level of the annular cartilage and transected at the junction of the horizontal and vertical canals. Care is taken to avoid the facial nerve although it is usually deep to the proposed level of resection. A single-layer closure of the vertical canal to skin is performed with 3-0 monofilament non-absorbable suture.

Dehiscence of the suture line and stomal stenosis are the most common complications of this procedure occurring in 12% and 3% of cases respectively (2).

Comment-This is a good surgery with good results IF the right patient is selected. The horizontal canal must be free of disease and patent for this surgery to be effective. In most of the cases we see with chronic ear canal disease both the vertical and horizontal ear canals are involved thus eliminating this procedure as a good surgical choice.

Total Ear Canal Ablation and Bulla Osteotomy

Total ear canal ablation (TECA) is the most common surgical procedure performed on canine ears within our practice. Although the procedure has been described as salvage in nature, we find it one of the most rewarding procedures performed for patients and their owners. Removal of the source of pain for the patient and the satisfaction of owners who do not have to medicate chronically diseased odiferous ears results in a good quality of life for the animal and a high degree of owner satisfaction. A relatively high complication incidence including facial nerve paresis/paralysis, chronic fistulation, incisional infection/dehiscence, inner ear disease signs (nystagmus/circling, ataxia), and hemorrhage are minimized with careful and knowledgeable surgical technique. In addition, most complications are short-lived except for facial nerve paralysis or fistulation secondary to incomplete removal of secretory epithelium from the bullae.

Indications for TECA and lateral bulla osteotomy (LBO) include end-stage Otitis Externa, neoplastic disease of the ear canal, and certain congenital malformations. Owners should be counseled closely preoperatively in regards to potential complications. Besides concern with the cosmetic appearance of the ear afterwards (normal pinna but no opening) most owners are concerned about whether the dog will be deaf. Seemingly, many dogs have decreased hearing prior to surgery and while TECA does not improve the hearing dogs usually maintain some sense of hearing afterwards. Careful physical examination is performed especially in regard to facial nerve function. We do not routinely perform skull radiographs prior to TECA/LBO since it rarely alters our therapeutic plan. If however neoplasia is suspected, (unilateral disease in a non-typical geriatric patient, or periaural abscessation) we either radiograph the animal and/or perform computed tomography (CT).

The animal is placed in lateral recumbency and a tear-dropped or modified T incision made around the external auditory meatus and extending down the vertical canal. The incision should encompass all of the hypertrophied tissue on the pinna. Incision and control of hemorrhage with electrocautery around the periphery will assist in visualization of the field. Similarly, placement of retractors, Gelpis or "Star" self-retaining retractors will assist greatly in performing the surgery. If an assistant is available, counter-traction on tissue to be excised aids the surgeon greatly. Dissection is performed as close to the ear canal as possible using a curved hemostat or Freer elevator. The facial nerve leaves the stylomastoid foramen on the caudal aspect of the horizontal canal and should be protected and gently retracted during the procedure. Removal of the canal at the external acoustic meatus is with a scalpel blade incising from caudal to cranial to avoid the nerve. The ventrolateral bulla and opening to the bulla is enlarged using a rongeur and the contents of the bulla gently curretted avoiding the dorsal and dorso-medial aspects of the bulla. Aerobic and anaerobic cultures of the bulla are performed and antibiotics administered intravenously following the cultures. Branches of the external carotid artery and auricular veins are in close proximity to the bullae and represent sources of hemorrhage. Direct pressure and packing-off of the area are most effective in controlling hemorrhage from these vessels if it occurs. Extensive irrigation of the operative site is performed followed by closure of the soft tissue within the surgical wound. In the past, many surgeons have routinely placed passive drains (Penrose) in the surgical wound to provide wound drainage for 24-48 hours. A previous study has led many surgeons to not routinely place drains in these animals. Should drainage be deemed necessary, a loose fitting and carefully placed bandage is used to cover the drain. Bandaging if placed incorrectly may cause constriction of the pharynx and airway obstruction. Antibiotics are continued for 2-4 weeks based on the culture and sensitivity results. Facial nerve paresis/paralysis occurs in approximately 10-30% of animals following TECA but most resolve within 4-6 weeks if the nerve is intact.

A smaller percentage of animals (3-15%) may develop draining tract (s) (fistulas) following the surgery (3). This occurs later in the postoperative period (months to years) in most cases. Animals typically respond temporarily to empirical antibiotic therapy but definitive management usually involves reexploration of the surgical site and bulla for remnants of annular cartilage or incompletely removed epithelium from the acoustic meatus or bulla. The risk of facial nerve damage should be addressed with the owner before reexploation. I prefer a lateral approach and use the base of the zygomatic arch as a general anatomic landmark to lead me to the bulla; reculture of the bulla is indicated at surgery as well as submission of any excised soft tissue or bone for histologic examination. A ventral approach to the bulla has also been used for reparation.

TECA for animals with neoplastic disease has good long-term results if the disease has not spread/invaded outside the ear canal.

Postoperative pain should be treated aggressively in a prospective manner in animals undergoing TECA. We block the great auricular and auriculotemporal nerves during preoperative surgical preparation. Parenteral narcotics are administered during hospitalization and we discharge the animal with oral pain medication such as extended release morphine tablets or Tramadol and NSAIDs.

Comment- Total ear canal ablation and LBO is among the most common procedures we perform. It is also among the BEST procedures we perform for dogs and owners in terms of being FINISHED with a chronic problem. Veterinarians with surgical interest can become capable of performing this procedure by surgical instruction in continuing education laboratories and cadaver practice. In addition to surgical training for the procedure, the time required to perform the surgical procedure should be considered. Preparation of the surgical site is time consuming and depending upon surgeon experience and the extent of diseased tissue, TECA surgical time can range from 45 minutes to 2 hours per ear. In most but not all cases, we elect to perform bilateral TECA when indicated rather than stage the procedures however I know surgeons who routinely stage the procedure because of the time involved.

Nasopharyngeal and Otic Polyps in the Cat

There are many causes of upper airway disease in the cat. Veterinarians are well acquainted with nasal and frontal sinus disease secondary to viral infections. Neoplastic and fungal diseases also may affect the upper airways of cats. Less common pathology such as laryngeal paralysis and tracheal disease has also been described in the cat. In this lecture, we'll characterize and discuss nasopharyngeal and otic polyps which tend to affect young cats (2years or less). Occasionally, we diagnose the disease in middle aged animals which may represent new (de novo) disease or the recurrence of previously treated disease.

I. Nasopharyngeal & Otic Polyps (Inflammatory Polyps)

A. Clinical Signs

May be a history of chronic respiratory or otic disease. No relationship to FELV/FIV status. Clinical signs are related to the location of the primary mass, either respiratory or otic. These polyps arise from the medial aspect of the middle ear chamber (dorsolateral compartment of the bulla). These are slow growing BENIGN masses that may extend out the external ear canal OR through the auditory tube into the nasopharynx. It is generally thought that these polyps arise secondary to chronic inflammation caused by virus or bacteria. It is uncommon to identify a specific cause of the polyp. Congenital origins have been suspected.

Nasopharyngeal Polyps.................................Otic Polyps

Open-mouthed breathing ..............................Head-shaking

Stertorous respiration....................................Pawing at ear

Nasal discharge............................................Otitis externa, media

Sneezing/gagging..........................................Head tilt/Ataxia

Dysphagia......................................................Horner's Syndrome +/-

Otitis +/-........................................................ (Miosis, Ptosis, 3rd eyelid prolapse)

B. Diagnosis/Treatment

1. Sedation or Anesthesia to carefully examine the ear canal and/or the nasopharynx. A spay hook is a handy way to retract the soft palate cranially to examine for masses in the dorsal nasopharynx.

2. Otic polyps have a variable appearance but are usually smooth, pink, and cigar shaped.

3. Lateral skull radiographs may show a large soft tissue dense mass in the nasopharynx displacing the soft palate ventrally however radiographs are primarily taken to look at the bullae and not for polyp diagnosis per se. "Open-mouthed" radiographic views may show increased density within one (most common) bulla. Absence of radiographic signs does not rule out otitis media or the bulla as a source of the polyp.

4. Large nasopharyngeal polyps are easily diagnosed with the animal under anesthesia; the polyp may be palpated dorsal to the soft palate and visualized by retracting the soft palate rostrally with a Snook OVH hook. Stay sutures" can also be used especially if you anticipate incising the soft palate to remove the polyp although this is rarely necessary. In either case, you'll find that the animal needs to be in a relatively deep plane of anesthesia otherwise gagging will result from pharyngeal stimulation. Nasal polyps can be removed by steady traction and twisting of the polyp. The polyp should be removed along with its "stalk" which tapers at one end.

5. Local removal (avulsion) of a nasopharyngeal polyp will result in alleviation of clinical respiratory signs however recurrence rates of 15-50% have been reported if a bulla osteotomy is NOT performed.

Polyps that do recur usually do so within a year however I recently removed a polyp and performed bulla osteotomy in an animal that had a polyp avulsed 5 years previously by another surgeon (same polyp or new growth?). Is there harm/contraindication in avulsing the polyp and waiting to see if it regrows?? Not that I can ascertain or find reported but AGAIN if definitive treatment is desired performing a bulla osteotomy is strongly recommended.

6. Otic polyps usually appear as pink "cigars" growing in the horizontal canal. Cleaning the canal is often necessary to adequately visualize the polyp. Avulsion of the polyp MAY be performed with Alligator forceps however incomplete removal is likely. It has been suggested that recurrence rates following Otic polyp avulsion are higher than for nasopharyngeal polyps. I perform ventral bulla osteotomy followed by avulsion of the ear polyp in all animals with the condition. Following bulla osteotomy, the polyp is easily removed via traction with an Alligator forceps. Some surgeons might perform a lateral ear resection to excise the polyp but this is usually not necessary. Practicing veterinarians have reported to me that lateral ear resection and polyp excision has resulted in "cure" in some of the cases they've operated on.

C. Ventral Bulla Osteotomy

Performance of bulla osteotomy in the cat is quite straightforward as compared to the canine as the bullae can usually be palpated relatively easily.

7. Place the animal in dorsal recumbency with the cervical and ventral facial area prepped for aseptic surgery. Tape the head with 1 inch adhesive tape over the rostral mandibular rami.

8. Make a paramedian 4-6 cm skin incision from the bifurcation of the jugular vein extending rostrally. The incision is centered about the level of the vertical mandibular rami. PALPATE the bulla if possible to center the paramedian incision.

9. Continue the incision through the platysma muscle and use a mosquito hemostat and baby metzenbaums to bluntly and sharply expose the bulla medial to the digastricus muscle. Very small Gelpi retractors are a nice aid in maintaining exposure. Avoid trauma to the hypoglossal nerve and lingual artery medially.

10. Bluntly elevate muscle from the bulla and use an 1/8th inch Steinman pin to open the ventromedial compartment of the bulla. Extend the bulla osteotomy into the dorsolateral compartment of the bulla by removing the ventral septum between the two compartments. The spetum between the two compartments is actually incomplete dorsally so there is communication between the two compartments. Culture bulla contents and use a small currette to remove any tissue within both compartments of the bulla. Some authors recommend culturing for Mycoplasma. Culture results have been variable in different retrospective studies of bulla disease in cats.

11. Lavage the bulla with saline solution. I DO NOT routinely place a drain in these patients at this time and have not encountered problems (to my knowledge) with this approach. Drains in my experience with this surgery produce minimal amounts of fluid.

12. Close the deep musculature with 4/0 absorbable suture and the subcutaneous tissue and skin.

13. EXPECT Horner's syndrome postoperatively which usually resolves within 30 days. Horner's is not pathologic to the animal. I would typically have these animals on Clavamox in the perioperative time period until culture results return.

References

Kapatkin AS, Matthiesen DT, et al : Results of surgery and long term follow-up in 31 cats with nasopharyngeal polyps. J Am Anim Hosp Assoc 26:387-392, 1990

Faulkner JE, Budsberg SC: Results of ventral bulla osteotomy for treatment of Middle ear polyps in cats. J AM Anim Hosp Assoc 26:496-499, 1990.

Smeak D: Ventral bulla osteotomy in cats. In Proceedings of the 12th ACVS Veterinary Symposium, San Diego, 2002, 122-125.

Gregory CR, Vasseur PB: Clinical results of lateral ear resection in dogs. J Am Vet Med Assoc 182: 1087, 1983.

McCarthy RJ, Caywood D: Vertical ear canal resection for end-stage otitis externa in dogs. J Am Anim Hosp Assoc 28: 545, 1992.

Holt D, Brockman D, Sylvestre AM, et al: Lateral exploration of fistulas developing after total ear canal ablations: 10 cases (1989-1993). J Am Anim Hosp Assoc 32: 527, 1996.