Endoscopic ear surgery – a complement to microscopic ear surgery

Abstract

Wullstein, the founder of modern microscopic ear surgery, already used an oto-endoscope intraoperatively. However, it is only after the recent development of modern video-endoscopy with high-definition, 4K, and 3‑dimensional imaging that endoscopically guided surgery of the middle ear is gaining some importance. Key ventilation routes like the isthmus tympani and the epitympanic diaphragm can be visualized far better using an endoscope than with a microscope. Going through the external meatus, surgery of middle ear pathologies is possible without external incision. This type of primary endoscopic ear surgery has to be distinguished from secondary endoscopic ear surgery, where standard microscopic ear surgery is supplemented by endoscopic surgery. Having to hold the endoscope in one hand, surgery has to be performed single-handedly, which is awkward. In cases of extensive bone removal or excessive bleeding, the view through the endoscope lens is obscured; therefore; the endoscope cannot fully substitute the microscope. It is, however, an interesting adjunct to microscopic ear surgery.

Full text

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DOI 10.1007/s00106-016-0268-x
© The Author(s) 2016. This article is availableat
SpringerLink with Open Access.
S. Preyer
Ohrenschwerpunkt Karlsruhe am Diakonissenkrankenhaus, Karlsruhe, Germany
Endoscopic ear surgery –
a complement to microscopic ear
surgery
Microscopic surgery is the gold
standard for surgeries of the middle
ear, mastoid and lateral skull
base. In Germany, microscopic ear
surgery is performed at a very high
level, with very good results with
respect to control of pathologies
and hearing function. Endoscopic
ear surgery is gaining increasing
importance internationally as
an adjunct to microsurgery and
a further development of traditional
microscopic ear surgery. However, in
Germany, endoscopic ear surgery has
not yet gained general acceptance as
a routine procedure.
Background
Although endoscopic ear surgery is still
in its infancy, it is gaining increasing
attention internationally. e first rea-
son for this increasing interest is the pa-
tients’ wish for minimal invasive surgery
to avoid an external incision.
»The quality of endoscopic
images is at least equal to
microscopic visualization
Secondly, endoscopic visualization has
improved significantly during the past
decades due to high-definition (HD)
video imaging and wide-field endoscopy,
such that today, the quality of endoscopic
images is equal or in some aspects maybe
The German versionof this article can be found
under http://dx.doi.org/10.1007/s00106-016-
0251-6.
even superior to microscopic visualiza-
tion.
History
Modern ear surgery is based on use of
the operating microscope to v isualize the
delicate middle ear structures. Our con-
cepts of ear surgery and classification of
tympanoplasty were developedin the 20th
century. ese concepts still determine
surgical procedures today [23].
Ohnsorge at the Würzburg ENT clinic
was the first to describe intraoperative
use of an endoscope [14]. Aer pro-
posalstousetheendoscopefordiagnos-
tic purposes [3,13], Wullstein used an
“ototympanoscope” from the company
Storz with a diameter of 2.7 mm intra-
operatively in 1984. However, the de-
vice had to be held in both hands and
could therefore only be used for a control
look around the corner [30]. Nine years
later, omassin and McKennan inde-
pendently proposed a minimal invasive
approach and use of the endoscope for
second-look surgery aer cholesteatoma
surgery [10,31]. Both surgeons intro-
duced the endoscope into the mastoid
via a small incision within the course of
the retroauricular scar. omassin de-
scribed use of 30 and 70° endoscopes
to reduce residual cholesteatoma in the
tympanic sinus and the retrotympanum
[30]. Inthesameyear,Poeusedtheendo-
scopicapproachto inspectthe round win-
dow for perilymphatic fistulas [19]and,
in 2000, described endoscopic stapedio-
plasty for the first time [18]. Tarabichi
developed endoscopic ear surgery fur-
ther and published two case series with
38 and 165 patients in 1997 and 1999,
respectively, in whom he performed en-
doscopic surgery for cholesteatoma and
perforations of the tympanic membrane
without a microscope [24,25].
Subsequent publications describe two
types of endoscopic ear surgery: a sec-
ondary endoscopic approach, i.e. us-
ing the endoscope for an additional vi-
sual control in microscopic middle ear
surgery [20,31], and primary endos copic
ear surgery, i. e. all steps of surgery are
performed endoscopically [4,6,11,24,
29].
Approach
For endoscopic ear surgery, rigid endo-
scopes with angles ranging from 0 to 70°
and diameters of 2.7 to 4 mm are used.
Initial concerns that the heat at the tip of
the endoscope mightcause tissuedamage
have since been dispersed. It has been
shown that the temperature at the tip of
the endoscope is not as great as initially
estimated, simply because the endoscope
has to be removed from the ear at regular
intervals for cleaning purposes. Clean-
ing the endoscope and applying anti-fog
solution allow time to cool down [20].
During endoscopic ear surgery the
surgeon holds the endoscop e in one hand
while working in the ear with the other
(.Fig. 1). To allow this kind of single-
handed surgery, different surgical instru-
ment companies have developed special
surgical instruments with suction. Since
it is possible to look around corners with
the endoscope, curved ear instruments
have been developed that enable the sur-
geon to also work around corners. To
avoid time delays in special situations,
e. g. heavy bleeding during endoscopic
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Übersichten
Fig. 1 8Setup for endoscopic ea r surgery. aTheready-to-usemicroscopecanbeseenintheupper
left corner. bThe left hand holds the endoscope, while the right hand performs the surgery
Fig. 2 9Endo-
scopic middle ea r
anatomy. ST sinus
tympani,STS sub-
tympanicsinus,
RW round window,
star posterior sinus.
(Figuremodified
from [12] with
permission from
Elsevier)
ear surgery, the operating microscope
should always be ready for use in the
operating room. is allows the surgeon
to change to the microscope at any stage
of the surgery if necessary.
Secondary endoscopic ear surgery
Historically, secondary endoscopic ear
surgery is the older technique and was
developed beforeprimary endoscopic ear
surgery with the intention of improving
the outcome of cholesteatoma surgery
[30]. For viewing around the corner,
30, 45 and 70° endoscopes are used as
an adjunct to the microscope to clear
cholesteatoma from blind spots, i. e. the
epitympanum, retrotympanum, hypo-
tympanum and Eustachian tube orifice
[20,31]. For access to the middle ear or
mastoid, a traditional retroauricular or
endaural approach is used. Pathologies
are removed under the microscope and
the posterior wall of the external meatus
is either preserved or removed [30].
Use of the en dos cop e improves visua l
control around c orners and thus re sults in
reduction of the amount of healthy bone
to be removed and improved preserva-
tion of temporal bone anatomy [1,11,
24].isisparticularlytrueforregions
like the sinus tympani and hypotympa-
num, which are hard to reach micro-
scopically even aer extensive bone re-
moval [28,29]. Systematic endoscopic
anatomic studies have shown that mas-
toid cells which extend posterior to the fa-
cial nerve and below the jugular bulb can-
not be visualized under the microscope
and, therefore, residual cholesteatoma is
oen le behind in these areas [5,12,21,
29].
Primary endoscopic ear surgery
In primary endoscopic ear surgery, the
middle ear is approached via the exter-
nal meatus [25]withoutanexternalskin
incision [1,11,19,24]. is reduces
perioperative so tissue damage.
»The curvature of the
external meatus plays no role in
endoscopy
Sincetheendoscopeispositionedmedial
to the natural curvature of the external
meatus, the view of the middle ear is
much better than when using the mi-
croscope. A short tympanomeatal flap
is elevated in the osseous portion of the
external meatus to access the middle ear
[20]. Later, a small incision may be nec-
essary to harvest gra material, such as
tragal cartilage or muscle fascia. During
surgery, the endoscope remains lateral
to the annulus most of the time, as this
reduces the risk of damaging the delicate
structures in the middle ear. In cases of
large tympanic membrane perforations,
the anatomy and function of the ossic-
ular chain can be judged through the
perforation prior to opening the mid-
dle ear. Aer elevation of the tympa-
nomeatal flap, the oval window can usu-
ally be se en without bone removal, whic h
reduces the risk of damage to the chorda
tympani. Curved instrumentsare needed
for surgical manipulation of the stapes or
the region of the istmus tympani. ese
instruments are different from the typ-
ical straight instruments used for mi-
croscopic surgery [18]. Cholesteatoma
is removed starting in the middle ear
and proceeding into the mastoid, healthy
bone only being removed when needed
for accessibility. Due to the wide field
of vision, less healthy bone needs to be
removedinendoscopicthaninmicro-
scopic surgery. Reconstruction of the
ossicular chain and tympanic membrane
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is performed by traditional techniques;
however, this requires some practice, be-
cause handling the gra materials with
only one hand is more difficult.
Endoscopic ear anatomy
e endoscopic transmeatal approach
to the middle ear allows the surgeon
to see middle ear structures which, in
the past, were hidden from view using
the microscope. An adequate surgical
anatomy had to be developed to describe
endoscopic surgical steps in the middle
ear. It is possible that the changed view
of middle ear anatomy will improve
cholesteatoma surgery, as cholesteatoma
growth normally follows given anatomic
routes and precise knowledge of os-
seous anatomy should therefore improve
its removal. Since 2009, Daniele Mar-
chioni and coworkers have published
several papers on endoscopic middle
ear anatomy and suggest a nomencla-
ture and new classification of structures
according to practical aspects ([4,7–9;
.Fig. 2). ese authors define an upper
and lower retrotympanum, which are
separated from the hypotympanum by
the finiculus (earlier name: sustentacu-
lum promontorii) [5,9]. If the finiculus
is bridge shaped, cholesteatoma can
grow from the round window niche
along infracochlear cells towards the
petrous apex [9]. Of the middle ears
examined in a clinical study of children
undergoing middle ear surgery, 90%
were found to have a bridge-shaped
finiculus, whereas this was the case in
only 60% of adult ears [9]. e upper
and lower retrotympanum are divided
by the subiculum. Marchioni describes
recurrent cholesteatoma as originating
most oen from the subtympanic sinus
between the subiculum and finiculus [5],
particularly when it extends far poste-
rior to the mastoid segment of the facial
nerve or even posterior to it.
Endoscopically, the anterior epitym-
panum and the supratubal recess can al-
ways be visualized and, therefore, the
tensor fold can be accessed for surgical
manipulations [4,8,17]. In 1946, Chatel-
lier and Lemoine described and named
the epitympanic diaphragm, consisting
of the anterior and lateral malleolar liga-
ments, as well as the posterior and lateral
incudal ligaments which separate the epi-
and mesotympanum ([2,17]; .Fig. 3).
Under normal conditions, the epitympa-
num is aerated exclusively via the tym-
panic isthmus [15,21], which is limited
by the tensor tympani tendon anteriorly
and the medial part of the posterior in-
cudal ligament posteriorly. Endoscopi-
cally,itispossibletojudgethepatency
of the tympanic isthmus and to remove
mucosal folds or granulation tissue ob-
structing it. Prussak’s space is ventilated
via the pocket of von Tröltsch posteriorly
and is independent of the epitympanic
space—both anatomically and with re-
spect to ventilation [16].
Epitympanic cholesteatoma
Pathophysiology from an
endoscopic point of view
Based on endoscopic observations of
middle ear ventilation routes, it has
been hypothesized that selective dysven-
tilation of the epitympanum may be
a mechanism for development of epi-
tympanic cholesteatoma [21]: the typical
and not rare finding of an epitympanic
cholesteatoma with a normal tympanic
membrane and positive Valsalva ma-
noeuvre is oen associated with a re-
tracted malleus and a reduced distance
between the handle of the malleus and
the long process of the incus, or with
a blocked tympanic isthmus due to
congenital or acquired mucosal folds or
granulationtissue ([6]; .Fig. 3). Accord-
ing to this new hypothesis, retraction
of the pars tensa of the tympanic mem-
brane and atelectasis of Prussak’s space
are two distinct independent phenomena
leading to cholesteatoma [16].
New therapy possibilities
Performing endoscopic surgery for
epitympanic cholesteatoma allows the
surgeon to check the epitympanic di-
aphragm and the tensor fold. A new
ventilation pathway via the supratubal
recess can be created by dissecting a com-
plete diaphragm and tensor fold ([4,6];
.Fig. 3).
Abstract
HNO DOI 10.1007/s00106-016-0268-x
© The Author(s) 2016. This article is
available at SpringerLink with Open Access.
S. Preyer
Endoscopic ear surgery –
a complement to microscopic
ear surgery
Abstract
Wullstein, the founder of modern
microscopic ear surgery, already used an
oto-endoscope i ntraoperatively. However,
it is only after the recent development
of modern video-endoscopy with high-
definition, 4K, and 3-dimensional imaging
that endoscopically guided surgery of the
middle ear is gaining some importance.
Key ventilation routes like the isthmus
tympani and the epit ympanicdiaphragm
can be visualized far better using an
endoscope than with a microscope. Going
through the external meatus, surgery
of middle ear pathologies is possible
without external incision. This type of
primary endoscopic ear surgery has to be
distinguished from secondary endoscopic
ear surgery, where standard microscopic
ear surgery is supplemented by endoscopic
surgery. Having to hold the endoscope in
one hand, surgery has to be performed
single-handedly, which is awkward. In cases
of extensive bone removal or excessive
bleeding, the view through the endoscope
lens is obscured; therefore; the endoscope
cannot fully substitute the microscope.
It is, however, an interesting adjunct to
microscopic ear surgery.
Keywords
Middle ear surgery · Endoscopic surgical
procedures · Middle ear · Cholesteatoma ·
Tympanoplasty · Video-assisted surgery
It has been proposed that this surgical
manoeuvre might improve ventilation of
the epitympanic space and help in pre-
venting recurrent cholesteatoma. Fur-
thermore, ventilation of the epitympanic
space may be improved by the removal
of mucosal folds and granulation tissue
from the tympanic isthmus [4]. ese
surgical manoeuvres around the corner
can only be performed endoscopically.
us, endoscopicear surgeryopens a new
avenue of functional surgery, with the
goal of also improving ventilation [8].
Extensive bone removal is necessary
tomicroscopicallyremovecholesteatoma
deep in the hypotympanum or far pos-
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Übersichten
Fig. 3 9Endoscopic mid-
dle ear surgery in a patient
with epitympanic dysven-
tilation. aEpitympanic
cholesteatoma with an oth-
erwise normal tympanic
membrane. bMucosal
folds obstructing the isth-
mus tympani. cComplete
epitympanic diaphragm.
dDissection of the an-
terior malleolar foldto
open up the epit ympanic
space for ventilationvia
the supratubal recess.
SPT stapedius tendon,
SH stapes head, ED epi-
tympanic diaphragm,
PE pyramidal eminence
terior in a deep sinus tympani extend-
ing far beyond the facial nerve. By con-
trast, more healthy bone can be preserved
endoscopically and cholesteatoma is re-
moved under good visual control [5,9].
»Improved ventilation of the
epitympanic space can prevent
recurrent cholesteatoma
In 2013, Marchioni et al. proposed
a transmeatal, transtympanal endo-
scopic approach to the internal auditory
meatus as an alternative route to the
traditional translabyrinthine approach
[7]. In their anatomic studies, the inter-
nal auditory meatus and the complete
course of the facial nerve could be ex-
posed transmeatally without an external
skin incision.
Discussion
e basic principles of endoscopic ear
surgery are similar to those of micro-
scopic ear surgery, but the combination
of both extends surgical possibilities.
Basedonherteam’sownexperience
with 37 endoscopicear surgeries—27 pri-
mary and 10 secondary cases—the au-
thor believes that use of the endoscope
improves preservation of the ossicular
chain. e risk for damage of the chorda
tympani is reduced because the oval and
round windows can be visualized endo-
scopically without removal of the scu-
tum. In cases of second-look surgery,
it was possible to look around the cor-
ner and preserve previous reconstruc-
tions of the ossicular chain or cartilage
gras. Removal of cholesteatoma in the
retrotympanum was more reliable with
endoscopic visualization and in one case
with recurrent cholesteatoma in the ex-
tensive hypotympanum, with exposed in-
ternal carotid artery and avery deep pos-
terior retrotympanum, removal was only
possible endoscopically.
e author’s team has performed
transmeatal endoscopic surgery in four
children aged 4–7 years with congeni-
tal cholesteatoma. e ossicular chains
could be preserved in four cases; in one
case, the stapes and incus had already
been destroyed by the cholesteatoma.
Heavy bleeding and extension of disease
posterior to the semicircular canal into
the mastoid limit use of the endoscope,
such that the microscope was used in
these cases. Training of young surgeons
is easier in endoscopic ear surgery be-
cause trainer and trainee have the same
view of the surgical field. It was also
found that the whole team working in
the operating room was more involved
in cases where surgery was performed
endoscopically, as everybody can follow
all surgical steps on the screen “through
the surgeon’s eyes”.
»Endoscopic surgery of
cholesteatoma improves
preservation of the ossicular
chain
In spite of these advantages, endoscopic
ear surgery is spreading only slowly in
Germany. Presumably this is because
new surgical concepts have to be devel-
oped in conjunction witha new approach
to the middle ear and also due tothe lim-
itations of one-handed surgery. Since the
new concepts are sc arce and there are only
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Table 1 Clinical studies on endoscopic ear surgery
Publications in
chronological
order
Number of cases Aim of study Results Type of stu dy
McKennan K.X.
1993 [10]
12 patients Recurrent cholesteatoma
Endoscopic second-look ear
surgery: retroauricular incision
after microscopic canal wall up
surgery
No postope rative loss of sensiti vity
Less morbidity
No complications
Case series
Thomassin J.M. et al.
1993 [31]
80 patients Cholesteatoma
Comparison of A:
44 microscopic canal wall up pro-
cedures with B:
36 combined microendoscopic
canal wall up procedures
Recurrent cholesteatoma at second-look
after 12–18 months:
Group A: 47.7%
Group B: 5.5%
Retrospective study
on two consecuti ve
case series
Tarab ichi M.
1997 [24]
36 patients Cholesteatoma Clinical follow-up:
1 year postoperatively: 29/30 patients no
cholesteatoma
2 years postoperatively 10/13 patients no
cholesteatoma
Second-look after 2 years: 4/6 patients no
cholesteatoma
Case series
Tarab ichi M.
1999 [25]
165 patients 96 tympanoplasties
13 stapesplasties
56 cholesteatomas
88% tympanic membrane perforation
closed,
“Results comparable to literature and
own historical group of patients”
Retrospective study
Poe D.S.
2000 [18]
34 patients Laser-assisted stapedioplasty:
11 stapes mobilisation
17 endoscopi c stapedotomy
6 microscopic stapedotomy
Hearing at 0.5,1,2,3 kHz afte r 6 months as
in historical group of patients
No complications
Improved visualization of anterior crus
and anterior third of footplate with endo-
scope
Prospective study
Tarab ichi M.
2000 [26]
69 ears Cholesteatoma In 3 cases, changeover to mi croscope
with retroauricular incision
Mean follow-up 41 months
6 recurrent cholesteatoma
Retrospective study
Tarab ichi M.
2004 [27]
73 ears Epitympanic cholesteatom a Mean follow-up 43 months:
5 recurrent cholesteatoma
8 recurrent perforations or chain defects
No bone conduction l oss or facial nerve
injury
Case series
Migirov L. et al.
2011 [11]
20 patients Cholesteatoma Clinical follow-up after 1 year:
18 patients no cholesteatoma
12 patients not yet re-examined
Retrospective study
Sarkar S. et al.
2013 [22]
32 patients Stapedotomy:
30 endoscopic
2 microscopic due to gusher
Air–bonegap0.5,1,2,4kHz
Preoperative41.5 + 5.2 dB
3 months postoperatively 10.1 + 3.6 dB
Bone conduction change 0.1 + 0.7 dB
Case series
a limited number of valid clinical stud-
ies showing the benefit of endoscopic ear
surgery (.Table 1), most experiencedear
surgeonsarecautiousofadoptingthenew
technique into clinical routine at present.
Intraoperative use of endoscopes in
middle ear surgery has already opened
up new perspectives in ear surgery, in
spite of the slow spread of the method.
In the future, endoscopic ear surgery will
become an indispensable adjunct to mi-
croscopic ear surgery.
Conclusion
4Transmeatal endoscopic ear surgery
is a promising new technique.
4The transmeatal approach reduces
perioperative soft tissue damage.
4Wide-field 0 and 30 or 70° endo-
scopes allow visualization of hidden
anatomic spaces and working around
corners, i. e. epitympanum, hypo-
tympanum and retrotympanum, for
safe removal of cholesteatoma.
4Visual control of ventilation path-
ways,i.e.tensorfoldandisthmus
tympani, allow surgical manipula-
tions improving air passage to the
epitympanic space.
4Endoscopic anatomic studies indicate
that selective dysventilation of the
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Übersichten
epitympanum may be a mechanism
inducing epitympanic cholesteatoma
in patients with normal Eustachian
tube function.
4In the future, the new endoscopic
approach to middle ear pathologies
will also change the microscopic
approach to the ear.
Corresponding address
Prof. Dr. S. Preyer
Ohrenschwerpunkt Karlsruhe
am Diakonissenkrankenhaus
Diakonissenstr. 28,
76199 Karlsruhe, Germany
hno@diak-ka.de
Compliance with ethical
guidelines
Conflict of interest. S. Preyer is supported in or-
ganizing a workshop on endoscopic ear surgery by
Spiggle & Theiss.
This article does not deal with studies of animals or
humans.
The supplement containingthis ar ticle is not spon-
sored by industry.
Open Access.This articleisdistributed under the terms
of the CreativeCommons Attribution 4.0 International
License (http://creativecommons.org/licenses/by/
4.0/), which permitsunrestricted use, distribution,
and reproduction in any medium, provided you give
appropriate creditto the original author(s) and the
source,provide a link to theCreative Commons license,
and indicate if changes were made.
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