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Review Article: Surgical Management of Ear Disease

Ear disease may initially be considered as a dermatological problem. However, when faced with the chronic ‘end-stage’ ear (fig.1) it becomes a surgical challenge, but often a very rewarding one. 

fig.1 chronic hyperplastic otitis externa

Investigations prior to surgery should include a thorough work-up to define an underlying cause if possible.  We routinely offer MRI of the head as part of our investigations as this can be invaluable in terms of surgical planning, particularly where the disease process extends beyond the margins of the ear canal and bulla, or merely to confirm involvement of the bulla where otoscopy / radiology is inconclusive.

Here follows a brief overview of the surgical options commonly employed to manage ear disease.

1. Myringotomy:

A small incision is made in the caudoventral part of the tympanic membrane so that the middle ear can be flushed and material removed. Indications  include pathology of the middle ear, with no associated changes to the external ear canal.  It is therefore performed less often than the more invasive procedures listed below.  Nevertheless, it can be of great help in the management of primary secretory otitis media (PSOM – see case report below), or for collecting samples for microbiological testing.

2. Ventral Bulla Osteotomy:

More commonly used in cats and rabbits as increased musculature ventral to the bullae in the canine makes the approach more difficult in this species. As with the above technique, it is worth considering this procedure if there is pathology within the bulla in the rare absence of associated otitis externa. It is particularly useful for removal of polyps in cats as may result in less hearing loss with reduced patient morbidity.  However, it is not without complications; severe haemorrhage is possible during surgery as there numerous vessels, including the linguofacial vein and a branch of the external carotid running over the bulla ventrally. Damage to the structures of the middle ear with resulting Horner’s syndrome or vestibular signs is also possible.

fig.2 - intraoperative photograph of total ear canal ablation

3. Total ear canal ablation with lateral bulla osteotomy (TECA+LBO, fig.2):

 

This technique is probably the most useful surgical procedure when managing chronic otitis externa, especially where there is proliferation of the epithelium of the external ear canal and lining of the bulla.  It may also be useful when the ear canal is relatively unaffected but there is chronic, antibiotic-resistant otitis media and/ or externa.  TECA+LBO is a technically demanding surgery that should not be undertaken by the inexperienced surgeon as the complication and recurrence rates are notoriously high. These include haemorrhage, damage to the facial nerve and structures of the middle ear, Horner’s syndrome, necrosis of the pinna and sinus tract formation.  However, when performed correctly, TECA+LBO significantly improves the quality of life of the vast majority of patients with chronically painful ears.

fig.3 - diagramatic representation of surgical objectives for lateral wall resection

4. Lateral wall resection (Zepps fig.3, click to enlarge):

 

This procedure is designed to improve ventilation to the remainder of the ear canal.  As much of the inflamed medial lining of the vertical canal is left in place, irritation may persist and require on-going medical management.  Further pathological changes to the remaining tissues can occur despite optimal care, resulting in a disappointing surgical outcome; it is often dismissed in favour of more aggressive techniques.

fig.4 diagramatic representation of surgical objectives for vertical canal ablation

5. Vertical Ear Canal Ablation:

 

An intermediate surgery (fig. 4, click to enlarge) and not as technically demanding as TECA+LBO but only useful when pathology is limited to the vertical canal; i.e. the  horizontal canal and bulla should be disease free for this procedure to be successful.  However, this is not the case in the vast majority of chronically affected animals.

In summary, with chronic ear disease it is unusual for the entire canal including the bulla NOT to be affected; hence the latter two procedures outlined above may be of limited value unless the disease is mild; in which case consideration should be given to further medical management anyway.

Ear disease can be very effectively managed surgically when medical management has failed, especially where more aggressive techniques such as TECA+LBO are used.  These offer rapid relief of suffering for both the animal with a painful ear and the anxious owner, daunted by long-term administration of topical medication to their reluctant pet!