Surgical Removal of Feline Inflammatory Polyps
Daniel A. Degner, DVM, DACVS, Animal Surgical Center of Michigan, Burton, Michigan
Feline inflammatory polyps are pedunculated benign fibrous masses that are infiltrated with inflammatory cells. Also known as nasopharyngeal, otopharyngeal, or middle ear polyps, these masses are most commonly found in cats younger than 2 years of age. The masses originate within the auditory tube or from the rostral aspect of the dorsolateral compartment of the tympanic bulla (Figure 1). Polyps may extend into the pharynx via the auditory tube, the external ear canal via rupture of the tympanic membrane, or both.
FIGURE 1 Ventral view of the skull demonstrating the two possible locations of inflammatory polyps: the external ear canal and nasopharynx. Courtesy Dr. Daniel A. Degner
Clinical signs may include stertor, dyspnea, dysphonia, sneezing, coughing, nasal discharge, dysphagia, head shaking, vestibular signs, Horner syndrome, and purulent or bloody external ear canal discharge. Otoscopic and pharyngeal examination may reveal a mass in the ear canal or nasopharynx, respectively. Nasopharynx examination can be performed with rostral retraction of the soft palate with a spay hook.
Diagnosis & Treatment Approach
Diagnostic testing for suspected inflammatory polyps includes CBC, serum biochemistry profile, urinalysis, and FeLV and FIV testing. A complete otoscopic evaluation is performed with the patient under general anesthesia. The soft palate should be retracted rostrally to evaluate the left and right auditory tube ostia for a protruding polyp.
Chest radiography can rule out lower respiratory and metastatic disease (if malignancy is suspected). Skull radiographs —including open-mouth, lateral, lateral oblique (left and right), and ventrodorsal views—are also obtained (Figures 2 and 3). False-negative results are common with bulla radiographs. Computer tomography (CT) is sensitive for the detection of middle ear involvement.
FIGURE 2 Open-mouth radiograph of a cat with inflammatory polyps. Note the thickened bulla (arrow) compared with the contralateral normal bulla.
FIGURE 3 The very large soft tissue density (arrows) in the pharyngeal region of this lateral skull radiograph represents a large inflammatory polyp.
When auditory polyps are confirmed, traction removal followed by medical therapy is often the first line of treatment. If the polyp recurs, a ventral bulla osteotomy may be performed. Clients should be educated regarding the risks associated with both procedures.
Traction removal of nasopharyngeal polyps with medical treatment has a success rate of 89% to 100%, whereas traction removal of polyps extending into the external ear canal with medical therapy has a 50% success rate. The success rate for first-time surgery with ventral bulla osteotomy is about 98%.
Traction Method of Polyp Removal
With nasopharyngeal traction, the soft palate is retracted rostrally with a spay hook. The polyp is grasped with curved mosquito or small right angle forceps, and slow, steady traction is applied until the polyp releases.
With external ear canal traction, otoscopy is performed to identify polyp location within the ear canal. The scope is removed, curved mosquito or alligator forceps are placed into the ear canal to blindly grasp the polyp, and steady traction is applied until the polyp releases.
Analgesics are continued for 2 to 4 days after surgery. Oral antibiotics (eg, marbofloxacin) are administered for up to 1 month based on culture and sensitivity testing. If this information is not available, marbofloxacin at 2 to 4 mg/kg q24h PO is prescribed for 1 month.
Prednisolone 1 to 2 mg/kg/day PO should be administered for 14 days, followed by gradual dosage tapering over 14 days. Alternatively, dexamethasone at 0.25 mg q12h PO for 1 week can be used, then 0.25 mg q24h for 1 week, followed by 0.25 mg q48h for 2 more weeks.
In patients that underwent traction removal of a polyp from the external ear canal, a 50:50 mixture of fluocinolone acetonide–dimethyl sulfoxide (Synotic) and injectable enrofloxacin (Baytril, 22.7 mg/mL; bayer-ah.com) can be made as a topical ear medication administered into the affected ear q12h for 1 month. These medications can potentially be ototoxic, although to date this has not been reported as a complication.
Related Article: Exclusive Video: Polyp Traction in a Cat
Ventral Bulla Osteotomy
Indications
While traction with adjuvant medical therapy is a reasonable first-line treatment, ventral bulla osteotomy may be preferred for several reasons:
The polyp has recurred following manual traction removal and adjuvant medical therapy.
The polyp was incompletely removed, and the remaining portion cannot be removed with forceps via manual traction (Figure 4).
FIGURE 4 This nasopharyngeal polyp has a long thin stalk, which usually indicates that the root of the polyp has been retrieved.
The polyp can be seen behind the intact tympanic membrane.
The client wants the pet to undergo only one procedure with the best possible success rate.
Marked radiographic changes have occurred in the bulla (although some cats will still respond to traction and medical therapy).
The polyp extends into the external ear canal (although some cats will still respond to traction and medical therapy).
Postoperative Care
IV fluids should be continued for 24 to 48 hours or until the patient is eating. Analgesia is effectively maintained with transmucosal (oral) buprenorphine. Antibiotic selection should preferentially be based on culture results and sensitivity testing. If these results are not available, a 4-week course of antibiotics (empiric choice) is prescribed. An Elizabethan collar may be needed until external sutures are removed 10 to 14 days after surgery.
Complications
Learning surgical anatomy can help minimize complications when performing ventral bulla osteotomy. Horner syndrome (Figure 5) is seen in about 80% and 40% of cats undergoing bulla osteotomy and polyp traction removal, respectively. This complication usually resolves within weeks to months after surgery.
FIGURE 5 Horner syndrome in a cat following ventral bulla osteotomy. Note the miotic pupil, drooping upper eyelid, and prolapsed third eyelid.
Vestibular signs are unusual and typically result from aggressive debridement of the bulla with damage to the semicircular canals of the inner ear. This complication frequently resolves with time unless severe irreversible damage to the inner ear has occurred. Vestibular syndrome, when present prior to surgery, likely will not resolve after surgery.
Facial and hypoglossal nerve paralyses are rare. Infection is rare with appropriate antibiotic therapy. Polyp recurrence can be reduced with adjunctive medical therapy.
On the Cutting Edge
A CO2 laser can destroy remnants of the polyp in the middle ear via an aural approach. However, no studies have been published on the efficacy of this technique or any associated side effects.
Related Article: Exclusive Video: Ventral Bulla Osteotomy in a Cat
Step-by-Step: Ventral Bulla Osteotomy
Note: All images show the ventral view and are courtesy Dr. Daniel A. Degner.
What You Will Need
General surgical pack
Small Gelpi (2), ring (1), or Senn (2) retractors
Freer elevator
Suction with Frazier suction tip
Curved mosquito or alligator forceps
Spay hook
5/64” Steinmann pin with Jacobs chuck
Fine curette (ie, dental/ear curette)
Fine Lempert rongeurs or Kerrison up-biting rongeurs
Operating telescopes with 2.5× to 3.5× magnification and an operating headlamp will facilitate performing the procedure.
A ring retractor eliminates need for an assistant.
Steps
Step 1.
Position the patient in ventral recumbency, and place a small rolled towel on the dorsal aspect of the cranial neck. Incise the skin over the palpable extents of the tympanic bulla (B, dotted line). This incision should extend through a thin layer of muscle over the bulla, which includes the platysma and sphincter coli muscles. Be careful to minimize transection of the large lingual (LV) and facial (FV) veins located over the lateral and caudal aspects of the bulla. The hypoglossal nerve (not shown) is frequently visualized and can be gently retracted in a medial direction.
B = bulla, FN = facial nerve, FV = facial vein, L = submandibular lymph node, LV = lingual vein, M = mandible, W = wing of the atlas bone