Keywords
endoscope - otology - ear surgery - microscopes
Introduction
The last century witnessed a rapid advancement in otology surgery, especially over
the past few decades, which was helped by the refinement in optics and lighting of
microscopes. However, despite these advancement in microscopy, visualization of the
deeper recesses of middle ear was still limited. The advent of the use of endoscopes
in ear surgeries occurred in the 1980s, but it took time until endoscopes became widely
accepted. Nonetheless, the recent development of various endoscopic surgical instruments
coupled with high resolution cameras has resulted in a growing interest in otoendoscopy.
Therefore, the present study was conducted to assess the level of knowledge and use
of endoscopes among otology surgeons in different parts of India. We have also made
a comparison of their experience with the use of endoscopes and microscopes, alone
or combined, in otological procedures.
Materials and Methods
We designed a questionnaire which was uploaded to a Google form. It contained 18 main
questions (Annex 1) aimed at characterizing the experience of surgeons, the use of endoscopes in ear
surgery, and the perceived advantages of and concerns with endoscopic ear surgery
(EES) techniques, as well as their preference for endoscopes over microscopic or vice
versa based on their experience. After taking consent from the otologists and obtaining
the approval of the institutional Ethics Committee (under no. MAMC/70/05/2022/No.
431), the questionnaire was administered through a link sent via email and WhatsApp
to various otologists. The final dataset included the answers of 354 professionals
from different parts of India, including ear, nose, and throat (ENT) surgeons, and
experienced and novice otologists. The clinicians included were all performing ear
surgery in their practices, and they were identified through ENT groups on social
media.
Results
The study included 354 practitioners who shared their experience and opinions on the
use of endoscopes in the field of otology. In total, 147 (41%) participants had become
consultants 10 years after their residency, 64 (18.1%), after 20 years, and 33 (9.3%),
after 30 years ([Fig. 1]). The remaining participants were senior residents and junior residents in different
years of their training. Ear surgery was performed by343 (97%) of the participants,
but most of them had less than 5 years of experience in EES. The remaining 11 participants
(3%) include junior residents in their initial period of postgraduate training. Almost
90% of the respondents believe that the endoscope has a role to play in ear surgeries
([Fig. 2]). Endoscopes are used in the clinics and operation theaters (OTs) by 74.9% of the
participants, commonly in outpatient procedures, such as like examination under microscope
(endoscope), cautery patching, suction-clearance, intratympanic injections, grommet
insertion, and in surgeries like myringoplasty, ossiculoplasty, stapedotomy, skull
base surgeries, and cochlear implantation ([Fig. 3]). A total of 16.1% (57) of the participants, mostly first-year residents, had never
performed EES or any endoscopic ear procedure. Endoscopes are widely used in cholesteatoma
patients to look for residual disease in areas that are difficult to reach, but, in
the present study, 42.9% of the surgeons stated that endoscopes do not have a role
in cholesteatoma clearance in ear surgery, and the remaining surgeons use endoscopes
either at the beginning or the end of mastoid surgeries, in combination with microscopes
([Fig. 4]). In the present study 42% of the surgeons said that there is less need for revision
surgery in such cases in comparison to surgeries performed only with the aid of the
microscope ([Fig. 5]). According to the respondents, the main advantages of EES are the access to areas
that are hard to reach, safety, early recovery, and cosmesis, and the common complications
observed are injuries to the external auditory canal (EAC, with a rate of 39.3%),
the tympanic membrane (TM; rate: 11.3%), and the facial nerve and chorda tympani.
Endoscopes of various diameters and angulations have been used, but most surgeons
(63%) prefer the 4-mm 0° straight forward HOPKINS telescope (KARL STORZ SE & Co. KG,
Tuttlingen, Germany). The fact that EES is a one-handed surgery was the most common
challenge mentioned by the otology surgeons (83.6%); other challenges reported were
loss of depth perception, fogging of the tip, obstruction in the work space, and issues
with drilling ([Fig 6]). The learning curve in EES is long and 45% of the participants believe it to be
harder compared to microscopes. Almost 83% of the participants believe there should
be specific training to use endoscopes, as well as measures to introduce or encourage
their use.
Fig. 1 Graph showing the participants' experience in the field of otology.
Fig. 2 Graph showing the surgeon's view of the role of the endoscope in otology.
Fig. 3 Graph showing various uses of endoscopes in the clinical practice of otologists.
Fig. 4 Graph depicting the otologist's perception of the role of the endoscope in cholesteatoma
surgery.
Fig. 5 Graph showing the need for revision in endoscopic surgery versus microscopic ear
surgery.
Fig. 6 Graph depicting the different challenges faced by surgeon's during endoscopic ear
surgeries.
Review of the Literature
Introduction of Endoscopes in Otology
In the 1950s, binocular microscopy revolutionized the field of medicine. In 1954,
Hopkins and Kapany[1] first introduced what they termed fibrescope, and, in 1967, Mer et al.[2] used the endoscopes to examine the middle ear. Initially, endoscopes were used in
the ear predominately as an adjunct to microscopes for diagnostic purposes.[3]
[4] Better lighting, image clarity, and wide-angle view provided by endoscopes helped
visualize the middle ear cavity via the transmastoid or transtympanic routes. In the
1990s, as an extension of these anatomic studies, researchers[5] assessed the use of endoscopes as observational tools in cholesteatoma procedures
to evaluate residual or recurrent disease, particularly after canal wall up (CWU)
procedures. Endoscopes were then used to examine the mastoid cavities a few months
after surgery, mainly in CWU procedures as well, to look for any residual disease,
which is known as second look surgery or transcutaneous mastoidoscopy.[5]
[6] Later, flexible endoscopes with smaller diameters were employed to understand the
normal anatomy and physiology of the eustachian tube (ET), and video endoscopy enabled
a meticulous analysis of the tubal dilation process.[7]
[8] In 1999, Klug et al.[9] used the ET as a portal for the endoscope to describe the anatomy of the middle
ear, and surgeons[10] started performing endoscopic ET procedures such as balloon tuboplasty and laser
eustachian tuboplasty.
Better Understanding of the Middle Ear Anatomy
The better understanding of the anatomy of middle ear with the advent of endoscopes
made the surgery of mastoid less invasive and more physiological.[11] Otoendoscopy is the best way to explore and understand all the areas of the middle
ear, especially the ventilation pathways to restore ventilation, which is the main
purpose of mastoid surgeries. Through endoscopy, Marchioni et al.[11] described in detail the anatomy of the middle ear, specifically the retrotympanic
and epitympanic spaces.
Endoscopes – A Teaching Tool
A randomized study with the application of a questionnaire was conducted by Anschuetz
et al.[12] to compare the suitability of using microscope- and endoscope-based methods to teach
the anatomy of the middle ear. The authors[12] concluded that the endoscopic approach was associated with an improved gain in knowledge
compared to the microscopic approach, and they stated that the participants subjectively
preferred the endoscope for educational purposes.
Bowdler and Walsh[13] compared the accessibility of various middle ear subsites using rigid otoendoscopes
with angles of view of 0° and 70° and 4.0 mm and 2.7 mm in diameter respectively,
and operative microscopes. In CWU procedures, 0° endoscopes provided good visualization
of the sinus tympani, facial recess, protympanum, attic, as well as for posterior
tympanotomy, while 70° endoscopes are better for the sinus tympani and ET. Karhuketu[14] reported similar advantages with endoscopes of angle of view of 0°, 30° and 90°
(1.7 mm diameter). Otoendoscopy is often limited by the curvature of the EAC. Mackeith
et al.[15] conducted a study on the thermal properties of the endoscope in otology surgeries
and found that the maximum recorded temperature was of 104.6°C at the tip of a 0°
endoscope with 4 mm in diameter and 18 cm in length,. The smallest recorded temperature
rise was for the 30° endoscope with 3 mm in diameter, 11 cm in length, whose tip reached
only 33.0° C. However, interestingly, the 70° endoscopes produced significantly more
heat than the 30° endoscopes of the same diameter.
Microscopes Versus Endoscopes in Otology
Although modern microscopes provide excellent views of the surgical field, their role
in the visualization of the deeper recesses of the middle ear is limited. These limitations
(which are overcome with the use of endoscopes) include inadequate amount of light
reaching the surgical plane, and the need to drill bone and/or retract soft tissue
to adequately visualize or access the different areas. Transcanal EES (TEES) uses
the EAC as a minimally-invasive surgical portal to access the middle (and inner) ear
disease. When introduced in the 1960s, endoscopes had poor image resolution in comparison
to the operative microscope, which limited its application.[2] But, with the introduction of high-definition (HD) video systems, endoscopes now
provide ultra-high-resolution images of the middle ear, which has expanded their application
in the field of otology.
At the Massachusetts Eye and Ear Infirmary, Cohen et al.[16] introduced a system to classify the use of endoscopes during otologic surgery. Class 1 pertains to the use of endoscopy for inspection without dissection; class 2 involves the combined use of the endoscope and the microscope, and it is subdivided
into classes 2a and 2b, in which the endoscope is used for less than 50% of the dissection
and more than 50% of the dissection respectively; and class 3 pertains to the use of the endoscope for the entire surgery.
Advantages of ESS
The many advantages of the EES, which have led to its increased preference, include:[17]
[18]
[19]
[20]
-
A wide angle of view: the endoscopic view usually includes the whole tympanic ring
and ear canal at the same time. This provides a complete view of the middle ear space,
tympanic membrane, and ear canal without the need to continuously repositioning the
patient's head, as in microscopic ear surgery (MES) ([Fig 7A,B])
-
The endoscope provides better visualization of structures that are lateral to the
viewing axis of the microscope. It is usually necessary to position these structures
at a right angle to the axis of the microscope for adequate visualization, which is
difficult to impossible in certain situations. Due to the dynamic range of endoscope
movement, if required, the 30° scope and the wide-angle 0° scope provide excellent
visualization of hidden structures and possible injuries to them, such as anterior
tympanic membrane perforation, and the retrotympanum, attic and hypotympanum. This
is also possible through a transcanal approach, even when using the 0°, because of
the wide-angle view of the more recent endoscopes.
-
The ability to visualize past the shaft of larger surgical instruments such as drills.
The handle of the instruments may obscure the visualization of structures in MES.
-
It is a great teaching tool.
-
The anatomical variations (tortuous or stenotic ear canal, anterior meatal overhang
etc.) that hamper the view of the entire tympanic membrane during ear surgery can
be overcome by the use of endoscopes.
-
Endoscopes enable close inspection and photodocumentation of the tympanic membrane
perforation, the drum remnant, the ET orifice, the middle ear mucosa, and the ossicular
chain without elevation of tympanomeatal flap.
-
Moreover, the perimeatal route renders postaural incision unnecessary, resulting in
a shorter operative time and lower rates of postoperative pain and morbidity, when
performed by experienced hands.
Fig. 7 (A) Microscopic view of middle ear on the left side. (b) Endoscopic view of the left ear after elevation of the tympanomeatal flap.(Note:
the wide-angle view obtained wirh the endoscope as compared to the microscopic view.
Abbreviations: F, facial nerve; P, pyramid; PC, processus cochleariformis; Pr, promontory;
RW, round window; ST, stapedial tendon; TT, tensor tympani tendon.)
Disadvantages of ESS[19]
[20]
[21]
-
The loss of depth perception and binocular vision, which are easily compensated for
with experience, are a disadvantage of ESS. Even though newer endoscopes might provide
depth perception, this issue is more related to the currently available scopes.
-
The one-handed surgical technique: since one hand is holding the scope, bleeding will
be a concern when proceeding with the next steps of surgery. It is always better to
address the bleeding points at the beginning to make the subsequent surgical steps
easier.
-
The need for surgeon training: acquiring the necessary skills should not be too difficult
for the experienced nasal endoscopist, but it might be hard for established otologists
who lack endoscopic training to make the necessary transition. Training will prevent
inadvertent injuries to middle ear structures and heat trauma.
-
Most of the equipment required is usually available in operating rooms; hence, the
cost is only significant if the earlier nasal endoscopic surgeries are not performed
at the concerned center.
Applications in the Field of Otology
-
Therapeutic Applications
-
➢ Tympanoplasty/ossiculoplasty
Various studies[21]
[22]
[23] on endoscopic transcanal tympanoplasty and cholesteatoma surgeries were performed,
with success rates similar to those of microscopic procedures.
Ravi et al.[24] compared the efficacy of endoscopy and microscopic transcanal inlay butterfly cartilage
tympanoplasty, and the endoscopic groups showed great success rates and improvement
in hearing.
-
➢ Mastoid Surgeries and Second-look Surgeries
Endoscopes have been used by many authors in mastoid surgeries to access the difficult-to-reach
areas, and they help reduce the morbidity of second-look procedures using a postaural
minimally-invasive approach.[6]
-
➢ Neurotology Surgeries
Endoscopes have been used in neurotologic surgeries such as those for vestibular schwannoma,
trigeminal neuralgia, and hemifacial spasm in combination with the microscope.[25] They provide good visualization of the geniculate ganglion and intra-labyrinthine
facial nerve.
-
➢ Endoscopic Stapedotomy
The use of endoscopes in stapedotomy is another novel application of TEES. The advantages
of using endoscopes in stapes surgery include good exposure without drilling the EAC
bone, avoiding chorda tympani manipulation, better visualization of the anterior crus
of the stapes to enable its removal without blind manoeuvres.[26] Singh et al.[27] conducted a prospective study comparing endoscopic and microscopic stapedotomy,
and they concluded that both techniques yield comparable audiological outcomes in
terms of ABG closure, but that the endoscope has a few advantages, such as better
visualization, decreased postoperative pain and dizziness, and minimal handling of
chorda tympani and canal wall curettage.
-
➢ Endoscopic Cochlear Implantation
Cochlear implantation is one of the new applications of endoscopes in the field of
otology, but there are few case series on this topic. In a recent study, Sharma et
al.[28] concluded that the visualization of the round window niche improved with the use
of an otoendoscope with 1.9 mm in diameter for cochleostomy and insertion of the electrode;
a similar conclusion was reached in the study by Jain A et al.[29]
-
Diagnostic Application
Because of their variable size and angulation, endoscopes have been used by otologists
to diagnose and manage various conditions, such as in the assessment of the extent
of retraction pockets and cholesteatoma,[30] ossicular status through the perforation like ossicular discontinuity, and fixation.[31] Endoscopes have negatively impacted the practice of young residents, as described
by Ng et al.;[32] in their study, 84.2% of the residents in programs with exposure to EES “felt that
its introduction had adversely affected their training, with 88.3 per cent of residents
agreeing that faculty members' learning of endoscopic ear surgery had decreased their
hands-on surgical load”.
Discussion
In the field of otorhinolaryngology, the performance of EES has been increasing rapidly.
Looking at the trend for the previous ten years, endoscopes emerged as very promising
tool in the management of ear diseases. In the present study, the 354 specialized
and general ENT surgeons who participated stated that they performed various types
of otological and skull base surgeries with the help of endoscopes. The present study
shows that almost all the institutions in India have introduced endoscopes in their
practice, both in clinics and operation theatres (74.9%). Regarding the perceived
advantages and complications or challenges faced during EES, most of the participants
(45.5%) find endoscopes harder to use than microscopes, while the remaining find endoscopes
are as hard to use (24.9%) or easier (29.7%) to use than microscopes. Most of the
participants believe there should be specific training in the use of endoscopes in
ear surgery; for that, the following measures can be introduced: computer simulation
training, endoscopic temporal bone dissection, and live surgery workshops. Various
education models have shown that a real-time video-assisted modality and non-real-time
surgical training are strongly favored, with an improved learning curve and greater
future opportunities to perform critical aspects of procedures.[33]
With the incorporation of suction into microinstruments, EES could become easier to
learn and perform. However, although the use of the endoscope has been proven to be
of value, particularly in procedures involving hard-to-reach areas with the microscope,
it is still viewed as a complementary method of performing ear surgery, used to augment
the existing methods. This has been demonstrated in the present study as 57% of the
surgeons felt the endoscope plays a complementary role in relation to the microscope.
The present study shows an increasing trend towards the use of endoscopes in surgeries
in the ear and base of the skull. Some of the participants have not yet used endoscopes,
but they believe that they should be introduced in the practice, as well as various
educational models. Several studies have shown that individuals trained with simulators
experience a measurable improvement in terms of operating efficiency, speed, and number
of errors.[34] Devices that use simulation technology could be used for residents to experience
and train for EES.
Endoscopes may have advantages over microscopes in various aspects, but, presently,
they cannot fully replace microscopes.
Conclusion
The present study shows that there has been a rapid increase in the use of endoscopes
in the otology practice in the last few years in India. However, maximum number of
participants showed interest in the learning or introduction of endoscopes in their
practice and suggested the various methods of learning of endoscopes in ear surgery.
So, we can conclude that there has been a definite increase in interest on the part
of otologists in the use of endoscopes in ear surgery, and the future of ontological
procedures looks promising.
-
➢ City/ State of practice:
-
➢ Do you perform ear surgery?
-
➢ Which of the following best describes your current level of specialty training:
-
➢ How long have you been performing endoscopic ear procedures?
-
Less than 5 years
-
10-20 years
-
20-30 years
-
More than 30 years
-
➢ In which setting do you use endoscopes in your practice?
-
➢ Please select the ear surgeries in which you use endoscopes. (Mark all that apply.)
-
➢ How many endoscopic ear procedures have you performed?
-
None
-
1-10
-
11-20
-
21-30
-
31-50
-
51-100
-
More than 100
-
➢ Please select the category which most appropriately describes your use of the endoscope
in cholesteatoma surgery. If you do not use it, please select “Not applicable”.
-
I use an endoscope at the end of the case to assess for residual disease
-
I primarily operate with the microscope, and use the endoscope sparingly to operate
in difficult-to-reach areas
-
I mainly use the endoscope, and reserve the microscope for cases of extensive disease
involving the mastoid
-
I exclusively use the endoscope
-
Not applicable
-
➢ Do you feel the endoscope plays a role in otological surgery?
-
➢ Select all alternatives that apply regarding the perceived advantages of endoscopic
ear surgery.
-
Safety
-
Cost
-
Ease of use
-
Superior visualization of the middle ear
-
More efficiency/Shorter operative time
-
Reduced recurrence/residual disease (cholesteatoma)
-
Better preservation of the ossicle and healthy tissue
-
Lower rate of postoperative morbidity
-
Better cosmesis
-
Faster patient recovery
-
Good teaching tool
-
Accessing difficult-to-reach areas
-
➢ Which of the following complications during endoscopic ear procedure have you come
across? (Mark all that apply.)
-
Tympanic membrane rupture
-
Facial nerve injury
-
Injury to the wall of the external auditory canal
-
Chorda tympani nerve injury
-
Other
-
➢ Which endoscope do you commonly use in your ear surgeries? (Mark all that apply.)
-
1.9-mm/Straight
-
1.9-mm/Angled
-
3-mm/Straight
-
3-mm/Angled
-
4-mm/Straight
-
4mm/Angled
-
➢ In your opinion, what are the challenges faced when switching from the microscope
to the endoscope in ear surgeries? (Mark all that apply.)
-
One-handed surgery
-
Loss of depth perception
-
“Fish Eye” effect/Distortion of field of vision
-
Limited magnification
-
Fogging of the endoscope
-
Obstruction of the working space by the endoscope
-
Application in narrow ear canals
-
Safety issues due to heat dissipation
-
Inadvertent trauma to structures by the tip of the endoscope
-
Access to specialized instruments
-
Problems with bone removal/drilling using the endoscope
-
➢ In your experience, compare the need for revision in procedures performed with endoscopes
alone and with the microscope.
-
Lower in comparison to the microscope
-
Higher in comparison to the microscope
-
Almost same in comparison to the microscope
-
I do not use the endoscope in surgeries
-
➢ In comparison to the microscope, how would you describe your overall learning experience
with the endoscope in ear surgery?
-
I find endoscopic ear surgeries harder than microscopic ear surgeries
-
I find endoscopic ear surgeries easier than microscopic ear surgeries
-
I find endoscopic and microscopic ear surgeries comparable in terms of difficulty
-
➢ Do you feel there is a need for specific technical training in the use of endoscopes
in ENT surgeries?
-
➢ If you have answered “Yes” or “Maybe” to the previous question, please select as
many of the measures mentioned below that you feel need to be introduced/encouraged.
-
Computer simulation training
-
Endoscopic temporal bone dissection
-
Live surgical workshop
-
Training opportunities under dedicated endoscopic ear surgeon
-
Other
-
➢ Mark your opinion regarding the following statement: “I will use endoscopes in ear
surgery in the future.”
-
I am already using them
-
Strongly agree
-
Agree
-
Neutral
-
Disagree
-
Strongly disagree
