Endoscopic permeatal “push-through” myringoplasty: hearing gain and graft uptake

Endoscopic myringoplasty allows full visualization of the external ear canal, tympanic membrane, and middle ear without the need to reposition the patient’s head. The endoscope allows accessing hidden areas and structures not properly viewed by the microscope such as sinus tympani, facial recess, and hypotympanum. It also provides sharp, magnified image and shortens the duration of the surgery. The postoperative pain and morbidity are reduced and hence the hospital stay. The aim of this work was to evaluate the efficacy of the endoscopic-assisted permeatal transperforation “push-through” myringoplasty by assessing the graft take rate and hearing results. Our study included twenty patients (14 females and 6 males) with chronic suppurative otitis media without cholesteatoma that underwent endoscopic-assisted permeatal transperforation myringoplasty. The case was considered '”successful'” if there was complete healing of the tympanic membrane and improvement of hearing. Graft uptake success rates were 85% with P-value 0.132. Average air-bone gap (A-B gap) preoperative was 18.20 dB; average A-B gap 1-month postoperative was 7.75 dB. Endoscopic transcanal myringoplasty provided sharp, magnified visualization and operability as it avoids retroauricular skin incision and minimizes surgical procedures to expose hidden areas. There is less bleeding, a shorter operating time, less postoperative morbidity, and minimal postoperative care.


Background
Early applications of the otoendoscope was in secondlook mastoidectomies to avoid postauricular incision during second-look surgery for cholesteatoma. Other applications of endoscopes in ears were examination of the middle ear recesses for residual cholesteatoma during cholesteatoma surgery, specifically the sinus tympani [1].
The role of the otoendoscope has expanded from a tool for diagnosis to the use as the sole visual device in otological surgeries. It provides a wider more comprehensive view from within with decreased tissue damage, at the expense of one-handed technique and loss of depth perception [2].
The use of the otoendoscope in myringoplasty is not only for assessment but also for the repair of the tympanic membrane perforation. It provides a sharp magnified vision. It allows the surgeon to switch easily from a close-up to wide vision just by moving the endoscope back and forth [3].

Methods
This is a prospective study that was conducted on 20 patients admitted at the Otorhinolaryngology Department, Kasr-Al Ainy Hospital, Cairo University suffering from chronic suppurative otitis media without cholesteatoma during the period from August 2019 until February 2020.

Open Access
The Egyptian Journal of Otolaryngology All patients signed a consent for conducting the study. All patients were subjected to a preoperative assessment protocol that included the following: • Full history taking of the ear condition with past history of medical or surgical treatment and history of any general medical conditions and special habits of medical importance • Examination of the ear using the otoscope and otoendoscope to confirm diagnosis of CSOM (safe type) and to detect size and site of drum perforation, ear discharge, condition of the middle ear, and exclude scars of previous operations. Tuning fork tests (Weber & Rinne) were performed. Other ear was examined and assessed. • Nasal and oral examination were carried out to exclude any other diseases or risk factor. • Preoperative audiological assessment including PTA and tympanometry • Routine preoperative laboratory investigations The surgical procedure 1. The surgical procedure was performed under general anesthesia.

2.
A total of 2.7-mm endoscope (0°) was used in all cases. 3. The endoscope was introduced through transcanal route. Wax and debris, if present, were removed from external canal. Visualization and assessment of the perforation, ossicular chain, middle ear mucosa, and eustachian tube opening were performed. 4. Trimming of the perforation edges using a needle and a forceps 5. Round knife was used to curette the under surface of the drum. 6. The perforation size was measured using a 2-mm Rosen round knife ( Fig. 1) 7. The size of perforation was classified into the following: •

Postoperative care
Most patients were discharged on the same day and prescribed a systemic antibiotic and an analgesic. The patients were instructed to avoid any form of straining and avoid introducing water to the ear. Examination of the ear using otoscopy or otoendoscopy was performed in the outpatient clinic on a weekly basis for 1 month and then every 2 weeks for up to 3 months to evaluate the graft uptake and to detect any infection (Fig. 4). Pure tone audiometry was performed 2 months postoperatively. Complete healing of the perforation of the drum, in addition to the improvement in the air-bone gap, was considered a success.
The Statistical Package for Social Science (IBM SPSS) version 20 was utilized to analyze the data in our study. The comparison between two groups was done by using chi-square test, and/or Fisher exact test was used instead of chi-square test when the expected frequency was found less than 5. The p-value was considered significant as the following: • p > 0.05: nonsignificant • p < 0.05: significant • p < 0.01: highly significant

Relation between size of perforation and success of graft take
In small size perforation, graft take was 100%, in medium size perforation, graft take 71.4%, and in large size perforation, graft take 66.7% (Table 3). Graft success rates were 85% with p-value 0.132. In this study, the surgery was considered to be '"successful'" if there was complete healing of the tympanic membrane and improvement of hearing postoperatively (i.e., decrease in the A-B gap). Cases with residual perforation or no hearing improvement postoperatively were considered "failed. " Eighteen patients were considered successful, while 2 patients were considered failed.

Discussion
The endoscopic "push-through" cartilage myringoplasty technique has many advantages: no postauricular incision, no tympanomeatal flap, no ear packing postoperatively, minimal or no pain, 1-day surgery, shorter operation time (20-35 min), and relative low costs.
The endoscope's wide-field vision allows visualization of the entire perforation, and the undersurface of the tympanic membrane can also be assessed. This allows for repair of the perforation without any possibility of an iatrogenic cholesteatoma, unlike the conventional myringoplasty. Furthermore, endoscopic surgery gives better demonstration of the surgical steps, along with viewing of the anatomic structures in the same field, resulting in a better appreciation of their relationship [4].
In our study, the otoendoscope was utilized for inspection of medial surface of the tympanic membrane, as well as the status of ossicular chain. With the aid of the endoscope and curved instruments, removal of epithelial ingrowth from medal surface of tympanic membrane was feasible.
Endoscopic ear surgery is a one-handed technique. The rigid endoscope has to be held in the left hand having the right hand free to operate. This becomes a challenge when there is excessive bleeding. Many solutions can help to reduce the bleeding: preoperative local preparation, low and stable operative blood pressure, local adrenalin, and special instruments with suction [4].
In our series, bleeding presented as a challenge. It was due to contact of the endoscope and instruments with the canal wall. This was more evident in our first cases. Using only one hand for the surgery and suction prompted as   a learning challenge. Maintaining a low stable operative blood pressure and low pulse rate helped reduce bleeding. Adrenaline-soaked cottonoids also helped stop bleeding in the operative field. One other drawback of endoscopic myringoplasty is the difficulty to operate directly off the endoscope leading to neck strain and backache. Therefore, the camera and monitor were always used. This increased the weight of the endoscope, leading to arm fatigue.
Ayache in 2013 reported an uptake rate of 96% in the 1-year follow-up period in 30 cases operated upon [3].
Huang et al. in 2016 had a success rate of 98% in 6 months follow-up period in fifty cases using endoscopic myringoplasty with cartilage graft. His study had a hearing improvement of 8.9 dB in the air-bone gap [7].
Mokbel et al. in 2015 had a graft uptake rate of 100% in type 1 cartilage tympanoplasty in forty ears with a followup period between 6 months and 1 year. He had a postoperative hearing improvement of the air-bone gap of 8.50 ± 1.25 dB [8].
Singh et al. in 2013 with an uptake rate of 92.85% in twenty-eight ears at 2 year follow-up. They had an average postoperative air-bone gap of 15.65 dB [9]. Özgür et al. in 2016, after 6-month follow-up, had a success rate of 92.5% in fifty-three ears with hearing improvement, with a postoperative air-bone gap of 10 ± 7 dB. All of our surgeries were performed by the endoscopic transcanal approach; none needed microscope, nor the postaural or the endaural approach [10]. Usami et al. in 2001, in their study, had twenty-two myringoplasty patients treated with endoscopy with a follow-up period of 1 year. The perforation closure rate was 81.8%, and improvement in air-bone gap after surgery was 14.8 dB [11].
Karhketo et al. in 2001 reviewed the data of twenty-nine endoscopic-assisted myringoplasty patients with a followup time of 1 year. The perforation closure rate was 80%, and improvement in air-bone gap after surgery was 7 dB [12].
Raj et al. in 2001 performed twenty endoscopic transcanal tympanoplasties had a closure rate of 90%, and the postoperative air-bone gap was < 10 dB in 60% of the ears [13].
In the present study, we achieved comparable results with a graft uptake rate of 85%. There was a statistically significant improvement in hearing outcome, with ABG gain of 7.75 ± 4.82.
Unlike the microscope, the endoscope can easily be transported and used in temporary ear surgery locations that take place in far less prepared places. Also, the endoscope costs less than the microscope, so it can be an efficient substitute in the healthcare facilities which cannot afford a microscope.

Drawbacks and limitations of this study
Incorporating the endoscope in ear surgery has a steep learning curve. One-handed technique poses as a challenge. External canal wall injury and bleeding could be troublesome. Availability of camera and monitor is mandatory to avoid back and arm fatigue. Operating on a larger scale for different tympanic membrane perforations regarding the size and site will give a better evaluation of the outcome using this technique.

Conclusion
The endoscope provides a wide and magnified field of vision, the ability to bypass bony overhangs or narrow areas in the external auditory canal with no need for repeated manipulations of the patient's head. The main drawback of the endoscopic ear surgery is that it is a single-handed technique.
Endoscopic push-through technique of cartilage myringoplasty is an effective, minimally invasive, and feasible method with good success rate in terms of graft uptake as well as hearing improvement. It could be considered a first-choice approach for small-and mediumsized tympanic membrane perforations.