Using video-otoscopy to better manage otitis externa/media in small animal practice

Chronic or recurrent otitis is a common and frustrating disease. A comprehensive approach to identifying and managing all predisposing factors, primary causes, and perpetuating features in each case is the key to successful therapy. In all patients presenting with clinical signs of ear disease, obtain a complete history and perform physical and otoscopic examinations and a cytologic evaluation. Additional testing may include culture and sensitivity, imaging of the tympanic bullae, allergy testing, an elimination diet trial, diagnostics for specific primary diseases (e.g. hypothyroidism), or otoscopy with the patient anesthetized. Further otoscopic evaluation under anesthesia is indicated in patients with suspected foreign bodies, severe acute otitis, purulent otitis, vestibular signs, or recurrent or chronic otitis.

In patients with signs of otitis, video-otoscopy provides several important diagnostic and therapeutic advantages over traditional hand-held diagnostic and operating-head otoscopes. Moreover, video-otoscopy can aid in record keeping and client education.

Improved visualization

Video-otoscopy offers superior optics and magnification to provide greater detail for evaluating the condition of the external canal and tympanic membrane. Even if the membrane was apparently intact on previous evaluation, small perforations and areas of necrosis, sclerosis, or opacification may prompt you to suspect concurrent otitis media. Otitis media was present in 82% of the ears of dogs with continuous or recurrent otitis externa of greater than six months' duration.1 And the tympanic membrane appeared intact in 27 of 38 ears evaluated under anesthesia with a hand-held otoscope.1 With otitis externa, the leading cause of treatment failure is unrecognized concurrent otitis media.2

Enhanced debris removal

The video-otoscope's configuration of lens, light, and working channel allows you to introduce instruments into the ear without shadowing or blocking the visual field, a common problem with operating-head otoscopes. Forceps, curettes, and catheters less than 5 F in diameter can be used to facilitate debris removal and sample collection. For irrigation during examination, sterile saline solution is safe and cost effective, and it permits continued visualization while the probe is immersed. Such visualization is not possible with operating-head otoscopes, because the light from the ear cone's base reflects off the fluid-air interface when the canal is filled with solution. Constant visualization permits you to target debris, enhancing the accuracy and effectiveness of cleaning while minimizing the risk of iatrogenic injury to fragile structures within the tympanic cavity.

Increased accuracy

In the case of otitis media with an apparently intact membrane, the video-otoscope can be used to more accurately direct diagnostic myringotomy and sample collection from the middle ear cavity for cytologic evaluation and culture and sensitivity. Such sample collection is useful because in as many as 89.5% of cases, the species or antibiotic sensitivity of bacteria obtained from the middle ear differs from that obtained from the external canal.,

When performing a myringotomy, be careful to aim for the caudoventral region of the pars tensa, avoiding the germinal epithelium in the area where the malleus attaches. With a video-otoscope, practitioners can perform this technique with more ease and confidence, because lighting and visualization are better.

Summary

The video-otoscope facilitates diagnostic and therapeutic procedures: It improves direct visualization, so you can better assess the external ear's condition and the tympanum's patency. The video-otoscope also allows for more precise sample collection for cytology and culture, biopsy, and myringotomy, and it enhances flushing and debris removal. Photographs and video recordings, other capabilities of video-otoscopes, provide a permanent visual record of the condition of a patient's external canal and tympanum. And a photograph can convey a patient's condition better than a verbal description when you re-evaluate a case, advise a client, or consult a colleague.

References
1. Cole, L.K. et al.: Microbial flora and antimicrobial susceptibility patterns of isolated pathogens from the horizontal ear canal and middle ear in dogs with otitis media. JAVMA 212:534-538;1998.

2. White, P.D.: Medical management of chronic otitis in dogs. Compend. Cont. Ed. 21(8):716-727;1999.