Discussion
The microscope has been a widely used tool for the otological procedure
and still considered as the gold standard in this field. It provides the
main advantage of bimanual handling along with stereoscopic vision,
better depth perception, and excellent
magnification.15 However, due to its straight line of
vision, it has a drawback of the inability to look around the nooks and
corners of the middle ear cavity like sinus tympani, retrotympanum,
epitympanum and tensor fold area.3,13,16 Anterior
perforation especially in cases with narrow canal or bony overhang needs
postaural approach and/or canaloplasty to perform the tympanoplasty.
Nevertheless, microscopic tympanoplasty for anterior perforation is
still considered as a high-risk case. The reasons for the lower success
rate in the closure of anterior TM perforation are insufficient
visualization, technically challenging procedure, decreased graft
viability due to poor vascularization, inadequate anterior membrane
remnant, and poor stabilization. 17
An endoscope, on the other hand, is a newly emerging tool in the town,
which is gaining popularity in our community. More and more surgeons are
now accepting it to be used for the surgery. Though it was first used by
Mer et al in 1967 as a tool to study the middle ear in cadavers and
animals, it became only famous when Tarabichi et al started to publish
widely and exclusively on transcanal endoscopic ear surgery especially
on myringoplasty and cholesteatoma.1 The scope of the
endoscope in ear surgery is expanding since then, not only limited to
cholesteatoma but ossicular reconstruction, stapes surgery, facial nerve
decompression, and even to excision of vestibular
schwannoma.3 We still need to wait what future brings
us more with the expansion of the use of the endoscope in otology.
Though temporalis fascia is still commonly used as a graft material, it
has been largely replaced by cartilage perichondrium graft especially in
high-risk conditions such as large or subtotal perforations, retraction
pockets, atelectasis, adhesive COM, and
cholesteatoma.5 Among them anterior perforation is
also considered among high risk due to its lack of vascularization,
stability, and support for graft. For this, cartilage-perichondrium
graft is an ideal graft for the surgery due to its stability and
long-term uptake result.12
In this study, we made an objective to evaluate if the endoscope holds
an advantage over the microscope for anterior perforation. Type I
tympanoplasty for anterior perforation using a microscope is difficult
to manage especially if the canal is narrow or the margins are not
adequately visible. We had graft uptake of 81.8% in the microscopic
group and 91.3% in the endoscopic group. The result revealed the
endoscopic group having better uptake outcomes than the microscopic
group however, it was not statistically significant. The mean operative
time was 68.68 ± 18.79 minutes in MT and 61.24 ± 11.18 minutes in ET.
Endoscopic tympanoplasty was faster than the microscopic group and it
was statistically significant.
Though endoscopic tympanoplasty avoids postaural incision, canaloplasty,
mastoid bandaging, it is technically challenging procedure as one must
master surgery using one hand. Even the little blood in the canal can
smudge the scope, making surgery difficult. These factors might be some
of the reasons behind the long surgical duration compared to other
studies. We experienced that with more practice the surgery got faster,
however, endoscopic surgery required a learning curve to overcome. On
the other hand, microscopic tympanoplasty gave the privilege of using
two hands for the surgery. Even if we were doing permeatal microscopic
tympanoplasty, speculum could be snugly fitted into the wide canal, and
still, two hands could easily be used for the procedure which is not
possible at all with the endoscope.
However, the postaural approach required more time to be spent on the
incision and suturing which was easily avoided in endoscopic
tympanoplasty. Thus, we could see that endoscopic ear surgery is
minimally invasive surgery decreasing the operation time, morbidity, and
complications.
A similar study but retrospective was done by Gulsen et
al.18 with an uptake rate of 93.7% in the endoscopic
group and 91.5% in the microscopic tympanoplasty with follow up of less
than 12 months. They had a significant difference in surgical time
between the two groups as well. The overall total surgical time in their
study is lesser than ours. Surgical time depends on the surgeon’s
experience as well as the learning curve.
A retrospective comparative study was also done by Kuo et
al.19 with a graft uptake of 97.3% in the endoscopic
group and 98.2% in the microscopic group but for central perforation.
However, this study had very short follow up of 3 months. The study had
significant difference in surgical time as well.
We could not find other literature that compared prospectively between
microscopic and endoscopic tympanoplasty in anterior perforation. There
are few studies published on total endoscopic transcanal ear surgery for
anterior perforation.
Tseng et al.7 published a retrospective study on
endoscopic transcanal myringoplasty for anterior perforation using
temporalis fascia and/or perichondrium as the graft and had uptake rate
of 93% among 59 patients with a follow up of a minimum of 6 months.
Another study was done by Ozdemir et al.12 on
endoscopic transcanal cartilage tympanoplasty in 104 patients, out of
which 35.6% had anterior quadrant involvement. The graft used was a
tragal perichondrium composite graft and had an uptake rate of 93.2% at
a minimum follow up of 6 months. A similar prospective study carried out
by Mohanty et al.10 on transcanal endoscopic cartilage
myringoplasty for anterior perforation in 87 patients had uptake result
in 91.9% at 1 year follow up which had similar uptake rate as our
result.
A systemic review was published by Visvanathan et
al.20 on techniques of successful closure of anterior
TM perforation. They described various techniques as anterior anchoring,
anterior hitch method, anterior interlay, anterosuperior anchoring,
endoscopic push through, butterfly, lateral graft tympanoplasty, hammock
tympanoplasty, Felix tympanoplasty, and endoscopic transcanal
techniques. The success rate ranged from 87-98% with a minimum follow
up of 6 months.
Other studies describing the techniques for the treatment of anterior
perforation includes the procedure that does not involve raising
tympanomeatal flaps such as endoscopic butterfly-inlay, endoscopic
push-through, and endoscopic transcanal inlay with graft uptake ranging
from 87.5 to 95.5% .11,17,21
There are different studies found in the literature comparing the
operative time between microscopic and endoscopic tympanoplasty. Huang
et al. 22, Choi et al.23, and kaya
el al.24, all compared surgical duration in both
groups and reported as endoscopic tympanoplasty being faster than
microscopic surgery which was statistically significant. However, their
study was done for the central perforation and the study was not
involving exclusively for anterior perforation as in our study.
All the studies mentioned above had significant hearing improvement pre-
and postoperatively, including those studies that used perichondrium and
cartilage perichondrium composite graft. In this study, we raised the
tympanomeatal flap to check the status of the ossicular chain, other
middle ear pathologies, and to perform underlay myringoplasty. This
ensures the stability of graft to avoid lateralization. There were no
postoperative complications noted in both groups.
Nine patients in the MT group required postaural incision to perform the
surgery due to a narrow canal and lack of visualization of the anterior
margin. All the cases in the ET group were completed via a transcanal
approach. It is all because of the wide-angle view of the endoscope
where the anterior margin could easily be seen. This adds up the
advantage of endoscopic surgery to be minimally invasive surgery
preventing complications as well as a financial burden which plays a big
role in a developing country like ours.
There are few limitations of this study which include small sample size,
lack of randomization and short follow up period. This could hamper the
generalizability of the results. In our opinion, the surgeon should also
be blinded during the surgery to decrease the bias especially if the
surgical duration is also considered in the study. The learning curve
could also be the factor that affects the surgical time.