Surgery STAT: Examining options to treat feline inflammatory polyps

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Sep 01, 2009


Catriona MacPhail
Feline inflammatory polyps (nasopharyngeal, middle ear, aural) are benign growths originating from the middle ear of cats and can result in upper-airway obstruction, otitis externa and otitis media.

Polyps are identified by otoscopic and/or nasopharyngeal examination. Diagnostic imaging (skull radiographs, CT) is indicated to document evidence of middle-ear disease. The origin and cause are unknown, but it is thought that polyps arise as a result of prolonged inflammation. It is unclear whether this inflammation initiates or potentiates the development and growth of inflammatory polyps.

Ongoing investigations into infectious-agent association with polyp development have yet to identify a definitive cause.

The two most common methods of polyp removal are by traction and ventral bulla osteotomy (VBO). Traction is effective; however, the owner must be made aware of the potential for recurrence.


Photo 1: Intraoral photograph of a cat with a nasopharyngeal polyp with the soft palate retracted rostrally by a spay hook. (PHOTO: COURTESY OF DR. CATRIONA M. MACPHAIL)
Nasopharyngeal polyps are visualized by retraction of the soft palate using a spay hook or stay suture (Photo 1). Rarely does the soft palate need to be incised for polyp removal.

Auricular polyps are visualized externally or by otoscopic examination. Regardless of location, the polyp is grasped with Allis tissue, alligator, or right-angled forceps and avulsed from its origin. Significant hemorrhage following traction removal is uncommon. A dental mirror or flexible endoscope helps visualize the nasopharynx following polyp removal to look for residual tissue.

Recurrence following removal by traction is reported to be approximately 40 percent; therefore conventional treatment advocates VBO to remove the epithelium of the tympanic bulla for definitive therapy.

However, one study describing prednisolone therapy following traction had a zero recurrence rate in eight cats vs. 64 percent recurrence in 14 cats receiving traction alone.

Response to prednisolone supports an etiology of chronic inflammation. Another study had recurrence in five of 14 (36 percent) cats treated with traction alone, but all of these cats had radiographic evidence of bulla disease. Results of these studies suggest that routine VBO for treatment of inflammatory polyps may not be necessary. Traction plus prednisolone may be a good option, particularly when no clinical signs or radiographic evidence of middle ear disease is present.


Photo 2: Intraoperative photograph of ventral bulla osteotomy. Soft tissues have been retracted using small Gelpi retractors. A hole has been made in the bulla using a large Steinmann pin. (PHOTO: COURTESY OF DR. CATRIONA M. MACPHAIL)
In cases of recurrence or chronic otitis media, exploration of the bulla from a ventral approach (VBO) is recommended. The cat is placed in dorsal recumbency with the head and neck extended over a sandbag or rolled towel. The bulla usually can be palpated through the skin. A small (3-4 cm) longitudinal incision is made over the bulla through skin and subcutaneous tissue. Blunt surgical dissection between the digastricus muscle laterally and the styloglossus and hyoglossus muscles medially, exposes the bulla, and residual tissue is removed from the ventral surface using periosteal elevators.