Nasopharyngeal Polyps in Cats
Dr. Nicholas Trout
Your veterinarian will take a careful history asking about head shaking, scratching, pawing or rubbing the ear against objects. There will be questions about balance, walking normally or circling to one side, abnormal movement of the eyes, drooping of the eyelids or prominence of the third eyelid, difficulty judging jumps, clumsiness or falling.
Following a general physical examination your vet will look at your cat's eyes, looking for drooping of the eyelid, small pupil size, prominent third eyelid, which may indicate damage to the nerves either within the middle ear or associated with it. The combination of drooped eyelid, eye set back in the socket, small pupil size and prominent third eyelid is called Horner's Syndrome. It can occur in middle ear disease and is a common complication following bulla surgery, but is usually transient.
No laboratory work is specific for polyps, but it may be helpful to rule out any other diseases prior to a general anesthesia. Testing for feline leukemia and feline immunodeficiency virus would also be appropriate.
For a thorough examination of the pharynx and ear canal, sedation or anesthesia is usually required. This will allow your veterinarian not only look down the throat, but also to pull back the soft palate in order to visualize a polyp. A thorough ear examination can be performed using an otoscope to see if the tympanic membrane (ear drum) is intact or not.
Radiographs (X-rays) of the skull can be helpful and are usually obtained under general anesthesia. A particularly useful view is called an open-mouth view, which highlights the middle ear, the bullae, so that the two sides can be compared. Normally the bullae should contain air and their content should be black on a X-ray.
CT scan or MRI can be useful to define the extent of a mass within the middle ear. For example, in an older cat, other tumors may be considered. The CT or MRI allows determination of invasion into the inner ear, the pharynx and the outer ear, more clearly than regular X-rays. It should be noted that up to 25 percent of animals with middle ear disease do not have any abnormalities seen on their x-rays.
In cases in which there is no evidence of a polyp in the pharynx or in the external ear canal, that is one in which the abnormality is confined to the middle ear alone, myringotomy may be performed to sample the contents of the bulla. Under anesthesia a needle is passed through the ear drum and fluid and cells are obtained for culture and cytology. Appropriate antibiotics can be started. In the case of a primary infection, or an infection secondary to a polyp or other mass in the middle ear, this often fails to provide adequate drainage of infected material, necessitating more aggressive surgery.
When a polyp is present in the pharynx, it can carefully be plucked out, attempting to get as much of the stock as possible. Some success has been reported using this technique, together with a course of steroids.
When X-rays show changes in the bulla, after removing the polyp from the throat, a ventral bulla osteotomy may be performed. This involves shaving under the neck and incising the skin to get access to the appropriate middle ear. The bony bulla is opened and the polyp and infected tissue removed and flushed. A drain may be inserted in the skin incision for a few days.
When the polyp passes through the ear drum, it may be removed by plucking. Alternatively an ear surgery may be performed to allow better access and drainage of the external ear. One such procedure is called a lateral wall resection and is usually reserved for those cases in which outer ear changes are more significant.
Cultures are obtained at the time of surgery and tissue is submitted for evaluation by pathologists.