The use of endoscopes in Otology can be traced back to the 1950s, when Hungarian scientist and Nobel Laureate Georg von Békésy, working at Harvard University, devised a small-diameter rigid endoscope that was passed through a tympanic membrane perforation to study the ossicles of the middle ear. The use of endoscopes in Otology has evolved considerably from research applications, otoendoscopy, and now endoscopic ear surgery (EES), based on the seminal work of Bruce Mer, Dennis Poe, Jean Marc Thomassin, and Muaaz Tarabichi. Otoendoscopy is defined as the use of a rigid fiberoptic telescope (or distal chip system) to examine the ear, and EES is the use of rigid telescopes to perform transcanal or transmastoid middle ear surgery. Along this spectrum lies office-based otoendoscopy, which refers to the use of endoscopes to facilitate and document the otologic exam and perform basic otologic procedures on awake patients in the office setting. The following chapter serves as a practice guide for otologic providers who are interested in incorporating safe and effective office-based endoscopy into their practice.

Otoendoscopy can be used for the diagnostic examination and management of pathologies of the external auditory canal (EAC), tympanic membrane, middle ear, and even inner ear. In most cases, a rigid 0-degree Hopkins rod telescope (10–18 cm in length, 1.9–4.0 mm in diameter) is coupled to a high-definition (HD) or 4K two-dimensional (2D) digital camera and video screen. The advantages of a rigid telescope over the binocular microscope during the otologic examination include (1) wide-angle view through small anatomic corridors, (2) enhanced depth of field, and (3) improved illumination of small spaces. Accordingly, the endoscope facilitates diagnosis of pathologies ranging from deep retraction pockets and anterior perforations to cholesteatoma.

With a tympanic membrane perforation or myringotomy, a small diameter endoscope (less than 2 mm) may be used to examine the middle ear. This can be useful, for example, to delineate the extent of cholesteatoma, examine the ossicular chain, and evaluate the round window niche to assess for perilymphatic fistula or the presence of a pseudomembrane. ^,

Otoendoscopy can be most safely completed using a 0-degree telescope and provides considerable advantages over otoscopy or microscopy. Although the use of a 30 or 45 degree telescope may be needed in selected cases to examine the depth of retraction pockets, we would caution the use of angled endoscopes only by the most experienced of otologic endoscopists due to the increased risk of inadvertent contact to the sensitive bony EAC .

The benefits of endoscopes can be leveraged for office-based otologic procedures, especially in patients with anatomical barriers such as a narrow or tortuous EAC or a stenotic meatus coupled with a complex mastoid cavity. In such cases, the endoscope enables superior visualization compared to the otoscope or microscope. The transition from otoendoscopy to endoscopic-assisted procedures can be challenging for most otologists who are accustomed to using a speculum to bypass cerumen and the hair of the meatus and guide and stabilize instruments. In addition, the reliance on “motion parallax” to assess depth perception when using 2D endoscopy may be unfamiliar to otologists who are only accustomed to binocular microscopy, unlike most rhinologists who routinely perform 2D-assisted endoscopic sinus surgery.

Endoscopy for digital photography and videography of the ear, cerumen removal, and mastoid cavity debridement using curved suctions and angled dissectors are common applications of otoendoscopy. Endoscopic-assisted transcanal procedures such as myringotomy, tympanostomy tube placement, transtympanic injections for middle and inner ear drug delivery, and even myringoplasty are also possible, but we would recommend that the provider gain technical experience in the operating room first.

Adherence to careful technique is crucial when instituting office-based endoscopy in order to optimize the quality of the examination, the patient comfort and safety, and provider ergonomics. First, the appropriate equipment must be selected and acquired. Various endoscopes are available with differing diameters and lengths. In our practice, we utilize Hopkins rods measuring either 2.7 mm in diameter x 11 cm length or 1.9 mm in diameter × 10 cm length. We find that these scopes balance providing a generous field of view and picture quality with being sufficiently small to be accommodated by most EACs. Another technology that is gaining in popularity and is well-suited to office-based endoscopy is a single-use (disposable) distal chip system. It is a lightweight handheld scope, 2.2 mm in diameter, and has built-in suction, permitting two-handed dissection, which may facilitate some office-based procedures. Other important equipment considerations are the light source and camera system. Any light source, such as xenon, halogen, or light-emitting diode (LED), is acceptable per the surgeon’s preference and institutional availability; however, the power must be kept at <50% to minimize patient discomfort and inadvertent thermal injury to the outer and middle ear. For the camera, we use a three charge-coupled device (3-CCD) HD 2D digital camera as opposed to dated single-chip systems that are prone to oversaturation, “red out,” and compromised image quality. Newer 4K video systems and 3D endoscopic cameras have been introduced with greater resolution and true depth of field when using 3D glasses and a proprietary video monitor, but we strongly believe that 2D HD is adequate for otoendoscopy as well as EES.

Supine patient positioning is essential for safety of otoendoscopy and endoscopic – assisted otologic procedures . The patient should be positioned supine with the head placed against the headrest of the exam chair and tilted slightly toward the opposite side. This enables a more secure patient head position and allows the clinician to stabilize the endoscope on the posterior external auditory meatus, minimizing tremor and hand fatigue. The camera cable and fiberoptic light cords should be supported on the exam chair or headrest and not laying on the ground, to avoid undue tension on the endoscope while being maneuvered within the ear . The 2D HD or 4K video monitor should be positioned directly across from the surgeon to optimize ergonomics during otoendoscopy and especially during an endoscopic-assisted clinic procedure. If possible, the video monitor should be positioned at eye level with the clinician to optimize ergonomic posture and reduce neck strain.

Lastly, a defogging solution is necessary to prevent the endoscope tip from fogging when inserted into the humid environment of the EAC. We have found that hand sanitizer works well for this purpose. Adherence to these principles will facilitate safe, high-quality, and comfortable otoendoscopy in the office.

For all procedures, proper patient selection is critical. The patient should be cooperative and able to tolerate endoscopic manipulation while remaining still. Furthermore, the pathology should be amenable to in-office intervention. For example, perforations amenable to in-office myringoplasty should ideally be central, <30% in size, dry, without extensive myringosclerosis, and without concern for epithelial ingrowth or ossicular discontinuity that would require formal tympanoplasty. Furthermore, the entire margin of the perforation should be visible—this is facilitated by endoscopic visualization, particularly for anteriorly based perforations. With proper patient selection, any of the previously noted procedures may be performed in standard fashion in the office with good results.

Outcomes of office-based endoscopy are favorable, given that it permits excellent wide-angle visualization and examination of the ear. The enhanced depth of field, high magnification, and superior illumination with a rigid telescope compared to microscopy provide an image that significantly enhances patient counseling.

There are few studies specifically evaluating outcomes of office-based endoscopy. On the diagnostic front, one study evaluated otoendoscopy for the diagnosis of otitis media in preterm infants and found it to be very useful with a high degree of concordance with tympanometry results. Another study from Japan looked at office-based transtympanic otoendoscopy to evaluate conductive hearing loss and found that they were able to detect ossicular chain abnormalities, aiding in diagnosis and preoperative planning, and counseling. And lastly, a study by Poe et al. described the use of transtympanic otoendoscopy to evaluate for perilymphatic fistula and even repair this with a blood patch.

On the procedural front, one study evaluated the benefit of otoendoscopy in debriding mastoid cavities. They found that this provided superior exposure and debridement compared to microscopy, allowing removal of material from areas inaccessible with the microscope. Another study described a bilayer porcine submucosa graft technique for in-office myringoplasty, with good closure and audiometric outcomes. Other studies on myringoplasty outcomes, while not necessarily performed in the office, can reasonably be extrapolated to the office setting as they would be able to be performed in the same fashion using office-based otoendoscopic techniques as described above. ^,

There is also much emerging interest and literature on the application of machine learning to otoendoscopic images, for example, to facilitate otitis media diagnosis. Several studies have reported the development of deep learning classification algorithms to diagnose otitis media using an endoscopic image of the tympanic membrane, and have shown that the diagnostic accuracy is superior to that of human clinicians. ^, As this technology is further developed, it could be used to aid in the diagnosis of various other pathologies of the external and middle ear as well. This represents an additional potential use case of office-based otoendoscopy.