Feline inflammatory polyps are not cancerous, but cause major problems for the pet
A simple surgery called polyp traction is a good first line treatment for this condition
Bulla osteotomy may be recommended in some cases
Overall the prognosis is very good following treatment of this condition
The middle ear is a hollow cavity (tympanic bulla) that has two chambers. The dorsal or upper chamber is about one third of the volume of the middle ear and it is bounded by the ear drum on one side, contains the small ear bones called ossicles (stirrup, hammer and anvil), and has a duct or tube called the auditory tube (that drains the middle ear cavity). The ventral chamber consists of the lower portion of the middle ear and it is the larger chamber and is filled with air.
Illustration right: VM = ventromedial compartment of bulla; DL = dorsolateral compartment of bulla; P = promonotory
Feline inflammatory polyps
Feline inflammatory polyps are pedunculated benign fibrous masses that are infiltrated with inflammatory cells. These masses are also known as nasopharyngeal, otopharyngeal, or middle ear polyps and are most commonly found in cats less than 2 years of age. They originate within the auditory tube or from the rostral aspect of the dorsolateral compartment of the tympanic bulla. These polyps may extend either into the pharynx via the auditory tube, the external ear canal via rupture of the tympanic membrane, or both.
Clinical signs may include noisy breathing, difficulty breathing, change of the voice, sneezing, coughing, nasal discharge, difficulty swallowing, shaking the head, vestibular signs (head tilt, continuous back and forth shifting of the eyes), Horner’s syndrome (constricted pupil, drooping upper eyelid, and prolapse of the third eyelid), and creamy or bloody discharge from the external ear canal. A mass in the ear canal and/or throat upon examination (requires anesthesia to do a complete exam).
Patients presenting with an inflammatory polyp should have blood tests performed which includes a complete blood count, chemistry profile, urinalysis, feline leukemia virus test, feline immunodeficiency virus test, chest x-rays, skull x-rays and a complete examination of the ears and throat under general anesthesia. Advanced imaging, such as CT scan may also be helpful in determining if the middle ear is involved with the polyp. The x-ray below left shows a very thickened tympanic bulla. The x-ray below right shows a large polyp (open arrows) in the throat of this cat.
Preparation for surgery
The pet should be fasted prior to surgery, as instructed by the surgical team. Water is usually permitted up to the time of admission to the hospital. The surgical team should be informed of any medications that your pet is currently receiving. Just prior to surgery, your pet will receive a sedative, have an intravenous catheter placed for the administration of intravenous fluids and intravenous medications, be induced under general anesthesia with medication(s), and have a breathing tube (endotracheal tube) placed to allow delivery of oxygen and gaseous anesthesia. If a ventral bulla osteotomy is to be performed, the surgical site will be clipped and cleansed with an anti-septic solution in preparation for surgery. While under general anesthesia, the pet’s breathing will be assisted with a ventilator and vital parameters such as heart rate, respiratory rate, core body temperature, blood pressure, oxygenation of the blood (pulse oximetry), exhaled carbon dioxide (capnography), and heart rhythm (EKG) will be monitored to ensure the pet’s well being. Pain will be controlled both during and after surgery with analgesics (pain-controlling medication). Please note that each surgical and anesthesia team may elect to chose a different, but effective analgesia protocol.
|As a first line treatment, polyp traction may be recommended. This involves grasping the mass with forceps and gently pulling it out of the throat or the ear canal. This procedure requires general anesthesia. About 40% of patients that have this procedure done will have Horner’s syndrome as a complication of the procedure; however, this complication is typically transient. If the polyp is extracted from the throat, the success rate is very high (89 to 100%), but medical therapy must be added to achieve this success rate. The video right demonstrates traction of a polyp from the throat in a cat. An instrument (spay hook) is used to retract the soft palate, the polyp is exposed and grasped with forceps, traction is applied, and the polyp is removed.
|Traction of polyps from the ear canal is about 50% successful when medical therapy is added. The video right demonstrates traction of a polyp from the ear in a cat.|
Medical therapy alone likely will not resolve the problem, but should be used as adjunctive treatment following traction of a polyp. This involves administration of analgesics for 2 to 4 days, administration of an antibiotic such as marbofloxacin or clavamox for 1 month, administration of or corticosteroid (dexamethasone or prednisolone) for 1 month, and administration of a cocktail ear medication (50:50 mix of Baytril/Synotic) into the affected ear canal twice daily for 1 month. This treatment is well tolerated by most cats.
Indications for Ventral bulla osteotomy
In some cases, the middle ear will be surgically entered in order to remove the “root” of the polyp. Ventral bulla osteotomy has a 98% success rate. Indications for surgery are subjective and include the following:
- Pet owner wishes to have only one procedure performed on their feline companion and have the best possible success rate
- Marked radiographic changes of bulla – some cats will still respond to traction and medical therapy
- Polyp extending into the external ear canal – some will still respond to traction and medical therapy
- Polyp is located behind an intact tympanic membrane
- Polyp that has been incompletely removed and remaining portion cannot be removed with forceps via manual traction
- Polyp that has recurred following manual traction removal
Ventral bulla osteotomy
An incision is made on the under side of the head, just behind the lower jaw bone (M) to expose the bulla (B). A thin layer of muscle, is incised over the bulla. Care is taken to avoid transection of large lingual and facial veins (LV and FV) located over along the sides of the bulla. The hypoglossal nerve frequently is seen and can be gently retracted medially.
A Steinman pin is used to make an initial hole in the bulla. The pin should be directed laterally so that the oval promonotory or other vital structures are not penetrated by the pin. A Lempert rongeur is used to continue the bulla osteotomy via the initial hole made with the Steinman pin (illustration right). A sufficient amount of the bulla wall is removed to give good exposure to the ventromedial compartment of the bulla and the septum of the dorsolateral compartment of the bulla.
Care must be taken to not disturb sympathetic nerve fibers (yellow fibers) that pass through the occiptotemporal fissure located on the dorsal caudomedial aspect of the bulla (see illustration right). In cats, these fibers are spread out along the promonatory, run dorsal to the bony septum, and then exit the bulla rostrally via another foramen. The septum is penetrated with a Steinman pin in order to enter the dorsolateral compartment.
A Lempert Rongeur is used to remove the septum. The most dorsal aspect of the septum may be left intact, thus protecting the sympathetic nerves as they pass in this region. Fluid from the bulla and a portion of the polyp should be submitted for culture.
The remaining root of the polyp located in the dorsolateral compartment is removed using a small dental or ear curette. The “root” may be located at the entrance to the auditory tube. Care must be exercised to prevent damage to the sympathetic nerve fibers. The bulla is lavaged with saline, and the muscle layer, subcutaneous layer, and skin are closed routinely. Surgical drains do not need to be placed.
Horner’s syndrome (photo right) is caused by injury to the sympathetic nerves that run through the bulla. It is seen in about 80% of the cats undergoing a bulla osteotomy procedure and about 40% of cats receiving polyp traction. This complication usually resolves within weeks to months after surgery. Polyp recurrence can be reduced with adjunctive medical therapy Vestibular signs (head tilt, continuous shifting of the eyeballs, walking in circles, rolling) are unusual and are typically due to aggressive debridement of the bulla with damage to the semicircular canals of the inner ear. This complication frequently will resolve 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 paralysis are rare. Infection is rare with appropriate antibiotic therapy
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