Although medical therapy is often effective in treating otitis externa, chronic otitis externa may progress to end stage otitis necessitating surgical intervention. Unsuccessful medical therapy for otitis externa may be due to the presence of horizontal or vertical ear canal neoplasia or polyps, generalized dermatological disease, simultaneous otitis media, and/or interna or irreversible hyperplastic ear canal disease. Total ear canal ablation combining bulla osteotomy and curettage is the surgical technique of choice in patients that have chronic, non-responsive ear disease that is unsuitable for or non-responsive to lateral ear canal resection.
While total ear canal ablation with bulla osteotomy (“TECA/BO”) may be the technique of choice, it is also a technique that should not be taken lightly, as post-operative complications can and do indeed occur. These complications are attributable to the technical difficulty of the surgical procedure and the potential for post-operative infection because of bacterial contamination of the surgical site, the most common post-operative complications encountered include facial nerve paralysis, head tilt, nystagmus, ataxia, hearing loss, hypoglossal nerve dysfunction, Horner’s syndrome, cellulites, abcessation, fistulation and/or dehiscence, and/or recurrent infection. In the majority of cases, the manifestation of these complications is temporary, however, because of the potential for long-term disability, excellent client communication is essential prior to surgical intervention. In addition, in those cases exhibiting aural manifestations of generalized dermatological disease, the client should be informed that persistent topical and/or systemic therapy may be indicated to control head shaking, pruritus, and odor even after aggressive surgical intervention.
In light of the association of otitis media with chronic end stage otitis externa, bulla osteotomy and curettage is indicated in conjunction with TECA to provide drainage of the tympanic bulla and reduce the post-operative complication rates experienced when TECA is performed alone. The surgical procedures advocated to achieve tympanic drainage are either ventral or lateral bulla osteotomy with curettage. In my experience, lateral bulla osteotomy is preferable to ventral bulla osteotomy because the patient does not have to be re-positioned after the TECA procedure. In addition, less soft tissue dissection is required of both procedures are performed through a single incision. Although it is difficult to perform a valid comparison of the two techniques because of the variability of the clinical features present in each case, the overall rates of recurrence or persistence of drainage appear to be lower when the lateral approach is utilized.
As mentioned previously, a high rate of complications may be observed if excellent attention to detail is not achieved throughout the surgical procedure. Facial nerve dysfunction may result from stretching or transecting the nerve because of its close association with the horizontal ear canal as it exits the stylomastoid foramen. Meticulous dissection of tissues as close to the perichondrium as possible should be performed to help prevent iatrogenic trauma. This perichondrial dissection sounds easier than it is, because the distortion of normal ear anatomy caused by fibrosis, ossification, and perioral abcessation make dissection difficult and may prevent visualization of the nerve. Iatrogenic damage to the structures of the middle and inner ear can occur during bulla curettage resulting in Horner’s syndrome, nystagmus, head tilt, and/or ataxia post-operatively. While affected tissue must be removed to reduce the risk of continued infection, gentle curettage avoiding the dorsomedial compartment of the bulla may help reduce the incidence of neurologic complication.
In an effort to achieve complete yet gentle curettage, I use sterile cotton swabs instead of a curette to remove the inflammatory tissue and associated debris from the bulla. Complete removal of the offending tissue is easily accomplished using the gentle curettage because of the degree of inflammation and infection of the epithelium of the middle ear is such that the tissue usually strips away from the bulla cleanly. Gentle yet copious lavage will usually remove any tags of tissue missed initially. Bacterial contamination of the surgical site is a given and thorough debridement and lavage must be performed to decrease the risk of post-operative sequelae. Cellulitis, drainage, fistulation, and reinfection is usually due to incomplete removal of the infected tissue, inadequate drainage, or primary closure of the surgical site. In order to avoid these complications, I place a penrose drain within the bulla and allow it to exit the ventral aspect of the incision to achieve optimal ventral drainage In addition, the incisional edges of tissue are not primarily closed, but are incompletely opposed with loose tacking sutures to allow the defect to fill in with granulation tissue.
The head is then bandaged and rebandaged as necessary (usually every 2 to 3 days) to prevent the accumulation of blood, pus, or serum within the wound. Drainage is maintained until the drain is non-productive, which is usually by the seventh day post-operatively. At this stage bandages may be changed every 5-7 days until contraction and reepithelialization is complete, which usually takes an addition 7-14 days.
Utilization of complete curettage, thorough debridement, lavage, drainage, and delayed closure affords an excellent opportunity for successful management of chronic otitis externa with a single surgical intervention. If reinfection and fistulation eventually develop, surgical exploration for remnants of infected cartilage or epithelium is required, as antibiotic therapy alone is usually fruitless and only ends up delaying the inevitable. If exploration is performed, a ventral bulla osteotomy is strongly recommended as fibrosis and loss of normal tissue plains makes identification of the facial nerve even more difficult.
In conclusion, TECA/BO and curettage is an effective means of treating end stage otitis externa. Long-term results are usually good to excellent and adherence to the principles outlined above will help minimize the occurrence of the unfortunate complications that can accompany surgical management for this disease.
Dr. Alan Schulman is a renowned Board Certified Veterinary Surgeon. While he is particularly known for his orthopedic, neurologic, and reconstructive surgical expertise, he...+ Learn More
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