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.