Introduction
Nasopharyngeal polyps occur in the nasal cavity, oral cavity, nasopharynx, Eustachian tube and tympanic bulla. They often arise in the tympanic bulla, extend down the Eustachian tube and enter the nasopharynx. They can also arise in the nose and extend into the nasopharynx or out of the nasal opening. They can also arise in the middle ear and extend through the tympanic membrane into the external ear canal.
Nasopharyngeal polyps are benign, pedunculated masses that contain or are covered in respiratory epithelium.
They occur most commonly in young cats and the mean age is 1.5 years, but they can also occur in older cats.
Aetiology is though to be congenital in young cats, and as a result of chronic inflammation in older animals, possibly associated with upper respiratory tract infections.
Clinical Signs
Clinical signs depend on the location of the polyp. The condition is usually unilateral, although bilateral cases can occur.
Polyps in the middle ear and external ear lead to signs of otitis interna, media and externa such as: head shaking, ear scratching, vestibular disease, Horner's syndrome, facial nerve paralysis.
Polyps in the naso or oro-pharynx are associated with signs such as: chronic rhinitis, nasal discharge, wheezing, stertor, sneezing and dysphagia, gagging and retching.
Diagnosis
Physical examination: under a light plane of sedation, the soft palate may be seen to be displaced ventrally or the mass may be visualised if the palate is retracted rostrally. Otoscopic examination may reveal masses in the ear canal if the inflammation is not too severe.
Radiography: may reveal a mass in the nasopharyngeal region. The bullae may be thickened if otitis media is present.
CT or MRI provide more detailed information about the mass and help decide on the appropriate treatment.
Treatment
Removal of the polyp is the only method of treatment possible.
Traction-avulsion: under general anaesthesia, the polyp should be grasped as close to the base of the stalk as possible, and pulled with steady, firm traction. For pharnygeal masses the soft palate may need to be retracted, and for ear canal masses the technique can be performed through an otoscope.
Bulla osteotomy: if bulla involvement is detected, this is the preferred method of treatment. A ventral bulla osteotomy is performed, the mass is resected and the epithelial lining of the middle ear is curetted. This increases the chances of removing the base of the mass, thus preventing recurrence.
Ipsilateral Horner's syndrome and facial paralysis can occur following removal, but most cases resolve spontaneously in 1-3 weeks.
Prognosis
The prognosis is good if all the polyp material can be removed. There is usually immediate resolution of the clinical signs.
The traction-avulsion method results in a 40% recurrence rate, and if bulla involvement is found, bulla osteotomy has the best prognosis and the least recurrence.
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References
Lappin, M. (2001) Feline Internal Medicine Secrets Elsevier Health Sciences
Norsworthy, G. (2010) The Feline Patient John Wiley and Sons