Advantages and disadvantages of endoscopic and microscopic middle ear surgery

1. ENDOSCOPIC
MIDDLE EAR
SURGERY
D R . D I V YA R A A N A
E N T P G

2. “Endoscopicandopticaltechnologicadvancementshavepushedus
towards yet another possible paradigm shift, and as we move into
the 21st Century we continue to explore and define the role of the
endoscopeinearsurgery.”

3. HISTORY OF
OTOENDOSCOPY
• Otologic surgery has progressed rapidly
over the past century .
• Before1920’s : loupes/without microscope
assistance.
• 1950s : Refinement of the binocular
microscopes.
• Late 60’s : use of microscope to visualize
middle ear was introduced.
• Early 1980s : Otoendoscopy was
increasingly used to inspect and diagnose
middle ear disease, particularly residual
disease after canal wall up mastoidectomy
procedures.

4. • Although the fibre-optic endoscope was invented in 1954 by Hopkins,
otoendoscopy only began with the use of the fibre-optic hypodermic
microscope by Long in 1965.
• Mer in 1967 involved practical issues with manoeuvring the great mass
of the microscope to attempt safe passage into the middle ear space.

5. INTRODUCTION
• In otology, the operating microscope
revolutionized ear surgery by improving
the accuracy and safety of operative
procedures.
• Indeed, the use of the microscope with
micro- instruments led to otology
being one of the first fields of minimally
invasive surgery.
• The advantages of the operating
microscope are obvious: it delivers a
stable image in the familiar head-on
view with the ability to vary
magnification while freeing both of the
surgeon’s hands to operate.

6. • However, its straight-line view is also the
microscope’s main limitation as it is unable
to navigate around anatomical corners to
provide a wide and variable direction of
view, unlike the endoscope.
• Modern advances in endoscope design have
provided a new tool for the examination of
anatomical structures in the middle ear and
more challenging applications extend to
neuro-otological operations such as the
removal of acoustic neuromas.

7. The endoscope is slowly emerging as
• a valuable adjunct to the operative microscope &
• the sole means for visualization and performing many routine and
complex otologic procedures for experienced surgeons.
The Endoscope is NOT meant to replace the microscope in all patients
may serve a specialized purpose in selective cases.

8. OTOENDOSCOPY VERSUS THE MICROSCOPE
One advantage of ear endoscopy over otomicroscopy is the wide field of view

10. • During microscopic surgery, the field of view is limited by the narrowest
segment of the ear canal. The use of an endoscope allows one to easily
bypass the narrow segment and look beyond without excising healthy
tissue for exposure.
• An anterior perforation can therefore be repaired entirely transcanal with
an endoscope, without the postauricular incision and canaloplasty often
required with microscopic techniques.

11. Narrow microscopic versus wide endoscopic view.
Cholesteatoma can be removed without extensive bony removal (often
avoiding a mastoidectomy) and without external incisions even with disease
extension beyond the antrum (as long as disease does not extend beyond the
limits of the lateral canal).

12. • Only a small amount of bony scutum needs to be removed to greatly
improve visualisation.
• A few millimetres of exposure is of exponential benefit in
approaches.
• The greatest benefit of the endoscope lies in exposing previously hidden
areas such as the sinus tympani, facial recess and anterior epitympanic
recess.
• On the other hand, the advantages of the otoendoscope are clear in
terms of its maneuverability, proximity of image, wide field of vision and
angle of view.

13. • Its direction of view is also variable and is influenced by the angulation of
endoscope employed, usually 0, 30, 45 or 70 degrees
Anatomy of the middle ear as viewed
with a 0° endoscope.

14. (a) 30° endoscopic view of the sinus tympani.
(b) 45° endoscopic view of the sinus tympani.
(c) 70° endoscopic view of the anterior epitympanum and
tensor tympani.

15. Anatomical classification of the sinus
tympani based on morphology and depth
on axial CT scan.
Type A – limited sinus tympani;
Type B – deep sinus tympani with medial
extension with respect to the facial nerve;
Type C – deep sinus tympani with
posterior extension with respect to the
facial nerve.

16. • Another example of this difference in access between the two techniques
is the facial recess.
• If approached through transcanal endoscopy, it ceases to be a recess and
becomes merely a small depression on the posterior wall of the
mesotympanum that can be reached within minutes of the start of the
operation.
• In contrast, microscopic technique requires a cortical mastoidectomy and
subsequent identification of the facial nerve, providing a limited key- hole
access in the space between the chorda tympani and the facial nerve.

17. Other Main Advantages of EES
1. Using the ear canal as the natural conduit to the tympanic cavity
2. High quality resolution and magnification
3. Restoring normal middle ear & mastoid ventilation routes
4. Preserving as much normal anatomy as possible by minimizing
unnecessary dissection of bone and soft tissue
5. Decreasing the need for drilling
6. Avoidance of postauricular approaches and minimizing damage to
neurovascular structures
7. Avoidance of scar

18. pr: promontory,
jn: Jacobson nerve,
hy: hypotympanum,
fi: finiculus
sst: sinus subtympanicus
se: styloid eminence
pe: pyramidal eminence
st: stapedial tendon
isj: incudostapedial joint
fn: facial nerve
m: manubrium
sp: short process
n: neck of the malleus
ttm: tensor tympani muscle
ttf: tensor tympani fold
ica. Internal carotid artery

20. LIMITATIONS OF OTOENDOSCOPY
One-handed technique
• The one-handed technique of EES is perceived as one of its major
limitations, especially among those who favour microscopic techniques.
• Similar to functional endoscopic sinus surgery (FESS), the non-dominant
hand holds the endoscope, and surgery is performed using the dominant
hand, resulting in a one-handed technique.

21. • The main function of the non-dominant hand in microscopic ear surgery
is to suction the operative field of blood, while the dominant hand
performs the vast majority of the important surgical dissection.
• Haemostasis is therefore essential in the setting of one-handed surgical
techniques. The minimally invasive nature of EES fosters a reduction in
local tissue trauma (less dissection, minimal incisions required) and
hence reduces troublesome bleeding.

22. Lack of depth perception
• Another perceived disadvantage of EES is the two-dimensional nature of the
operative image that limits depth perception.
• The endoscope creates a ‘fish-eye’ optical distortion whereby the periphery of
the operative field is more magnified than the centre.
• The optical distortion created by the endoscope predisposes surgeons to
misjudge distances and make the tympanomeatal flap too short.
• Using a surgical tool (i.e. round knife) to measure distance assists with
overcoming this when getting started with EES.

23. Limited instrumentation
Fogging and smearing of tip of endoscope
Safety considerations specific to EES:
Potential of thermal injury from tip of endoscope:
• Power of light source no greater than 50% and
• A safe distance of >5 mm from inner ear structures
In addition, the learning curve in otoendoscopy means that it will take some time
for the surgeon who is accustomed to an entirely microscopic technique to adapt
accordingly.
Lack of endoscopic experience or indelicate tissue handling may lead to unsafe
advancement during otoendoscopic exploration and possible forceful dislocation
fracture of ossicles

24. SUGGESTIONS FOR OVERCOMING THE LIMITATIONS
OF A ONE-HANDED SURGICAL TECHNIQUE
• Take a hands-on course on EES
• Start with a graded approach to case complexity
• Initial cases should be selected with favourable anatomy
• Start with a zero degree endoscope, and advance to angled scopes as
experience increases.
• Proper operative positioning with arm rests to provide support for both
elbows throughout the case to avoid fatigue and improve manual dexterity.
• Proper positioning of the monitor in a “neck neutral” position to avoid
fatigue.
• If necessary when starting with the technique for the first time elevate the
tympanomeatal flap with the microscope and then switch to the endoscope
upon entering the middle ear.
• Consider purchasing a suction round knife, an instrument that permits
dissection and suction simultaneously.

25. INDICATIONS FOR MIDDLE EAR ENDOSCOPIC SURGERY
DIAGNOSTIC USES:
• Extent of retraction pockets and cholesteatoma
• Ossicular continuity through perforation
• Otoendoscopy through myringotomy
THERAPEUTIC USES:
• Tympanoplasty/ossiculoplasty
• Retraction pocket surgery
• Mastoid surgery
• Minimally invasive second-look combined approach tympanoplasty

26. NEWER APPLICATIONS
• NEUROTOLOGIC SURGERY
• ENDOSCOPIC STAPEDOTOMY
• ENDOSCOPIC COCHLEAR IMPLANTATION

28. CONTRAINDICATIONS & POTENTIAL COMPLICATIONS
• No known absolute contraindications to EES.
• Any otologic case that may be performed via microscopic techniques
may be assisted by the use of an endoscope.
Potential complications of EES are identical to that of traditional
microscopic ear surgery;
• Direct damage to ossicles
• Direct damage to facial nerve
• Heat damage to inner ear
• Heat damage to facial nerve
There is no reason to believe that complications for EES are higher than
microscope-based approaches.

29. ENDOSCOPE SPECIFICATIONS
• Many otologists will use both operating microscope and endoscopes
symbiotically, performing part of their surgery with 2.7mm diameter 0, 30
and 45 degree endocopes and rarely, using the 70 degree endoscope as
well as the 1.9mm endoscopes, especially to pass through the posterior
tympanotomy.
• Others may undertake the majority of their surgery using a 14–18cm long
4mm diameter 0 degree Hopkins rod and endoscope, the very same
endoscope used for sinus surgery. This is known as EES. It is gaining
popularity among some otologists as the advantages of using a longer
and wider endoscope include a wider field of view, as well as the fact that
the surgeon’s hands are farther away from the ear canal and hence less
likely to interfere with one another intra-operatively.

31. CONCLUSION
• The microscope has traditionally been the workhorse of ear surgery but
modern advances in endoscope design and endoscopic surgical
techniques have ushered in a new era for the rigid endoscope as a key
tool in otology.
• The endoscopic benefit of exposing ‘hidden recesses’ and ‘blind spots’
in ear surgery is the primary rationale for the growing support of EES
over the last decade.
• The minimally invasive nature of the endoscopic approach affords
greater healthy tissue preservation and results in patient benefits that
cannot be ignored.