Endoscopic and Microscopic Tympanoplasty for Adhesive Otitis Media: A Comparative Prospective Analysis

Introduction

Tympanic membrane retraction is a condition that results in medial displacement of the tympanic membrane due to decreased middle ear pressure [1]. It is frequently localized in the posterosuperior quadrant of the pars tensa and pars flaccida [2]. Atrophic changes occur in the middle fibrous layer of the tympanic membrane secondary to prolonged eustachian dysfunction and chronic effusion. This results in atelectasis and adhesive otitis media [3].

Tympanic membrane retractions are often asymptomatic; however, symptoms such as hearing loss, otorrhea, and otalgia may occur due to erosion of the ossicular chain and adjacent structures. Therefore, the retracted membrane should be surgically removed after the onset of symptoms, reinforced by ossicular reconstruction, if necessary [4].

One of the most important reasons for failure in adhesive otitis media surgery is the difficulty in controlling the retraction limits and the high risk of iatrogenic cholesteatoma due to the epithelial residues. Endoscopic surgery provides wider visualization and reduces residues and recurrences [4].

While endoscopes have been used in ear surgery since the 1960s, transcanal endoscopic ear surgery (TEES) has been used in otological practice for only 30 years. TEES was first described by El-Guindy et al in 1992 [5]. Subsequently, Tarabichi et al, Marchioni et al, and Thomassin et al conducted studies on endoscopic ear surgery for cholesteatoma, tympanoplasty, and stapes surgery [6–8].

Tympanoplasty and middle ear surgery for tympanic membrane retraction can be performed endoscopically or microscopically. Although endoscopic tympanoplasty is a one-handed operation, its popularity has been increasing in recent years because it provides a good surgical view and is minimally invasive. One of its important advantages is better visualization of the retrotympanum without bone drilling [9]. In this study, we compared the results of endoscopic and microscopic cartilage tympanoplasties in patients with symptomatic pars tensa retraction and adhesive otitis media. We emphasize that all borders of the adhesive membrane can be evaluated better with the endoscopic approach than with the microscopic approach and that a more effective intervention can be performed under endoscopic vision.

Therefore, this prospective study aimed to compare outcomes and hearing improvement in 51 patients with adhesive otitis media following endoscopic and microscopic tympanoplasty.

Material and Methods

ETHICS STATEMENT:

This study protocol was reviewed and approved by the Ethics Committee of the Kocaeli Derince Hospital (approval number 2021-61). All respondents provided written informed consent before completing the survey and all research carried out in participants was in compliance with the Helsinki Declaration.

PATIENT SELECTION AND INCLUSION/EXCLUSION CRITERIA:

Fifty-one patients with adhesive otitis media who presented to our clinic due to otalgia, otorrhea, or hearing loss between April 2021 and April 2022 were included in this study. All patients underwent otoendoscopic and otomicroscopic examinations, followed by pure-tone audiometry. Retraction pockets were not self-cleaning and contained epithelial debris. Pars flaccida and scutum were normal in all cases. The preoperative jugular bulb, mastoid cells, and ossicular chain were examined using computed tomography. Patients with cholesteatoma and patients younger than 18 years and older than 60 years were excluded. Patients were divided into 2 groups – 26 patients with wide external auditory canal were assigned to Group 1 (endoscopic tympanoplasty, ET), and 25 patients with narrow external auditory canal were assigned to Group 2 (microscopic tympanoplasty, MT). Informed consent was obtained from all patients. The mean air-bone gap (ABG), 0.5, 1, 2, and 4 kHz pure-tone audiometry, and air and bone conduction measurements were taken preoperatively and at 1 year postoperatively in all patients. The postoperative otoendoscopic records of all patients were obtained. Endoscopic and microscopic tympanoplasties were performed by a single surgeon.

SURGICAL EQUIPMENT:

Rigid telescopes (0° and 45°, 14 cm length, and outer diameter of 3 mm) (Karl Storz, Tuttlingen, Germany), an LED light source, a shielded fiberoptic light head set, a 3-chip full HD camera head (Karl Storz, Tuttlingen, Germany), an HD Monitor (Karl Storz, Germany), a conventional ear microsurgical set, and an Opmi Vario S88 surgical microscope (Zeiss, Oberkochen, Germany) were used.

SURGICAL TECHNIQUES:

All patients underwent surgery under general anesthesia. Endoscopic surgeries were performed transcanally, and microscopic surgeries were performed retroauricularly. Before endoscopic surgery, a chondral-perichondral composite graft was harvested from the tragal cartilage. The retracted membrane was removed as much as possible by injecting saline into the tympanic cavity using a dental injector. Subsequently, vertical incisions made at the 12 and 6 o’clock positions were combined with a horizontal incision 5–6 mm from the annulus, and the tympanomeatal flap was elevated. The adhesive membrane was removed from the tympanic cavity, ossiculoplasty was performed if necessary, and the operation was terminated by over-undergrafting with the thinned cartilage (Video 1). In microscopic surgery, approaches similar to endoscopic surgery were applied following retroauricular sulcus incision.

FOLLOW-UP AND AUDIOLOGIC EVALUATION:

The patients were discharged the day after surgery. After 1 week, the external auditory canal tampons were removed, and otoendoscopic and audiometric evaluations were performed 1, 6, and 12 months postoperatively. In the pure-tone audiometric evaluation, bone and air conduction were measured at frequencies of 0.5, 1, 2, and 4 kHz. The ABG was measured. Graft status, the external auditory canal, and healing were evaluated otoendoscopically. Pure-tone audiometric data, ABG, and graft status were compared between endoscopic and microscopic groups at 12 months.

STATISTICAL ANALYSIS:

SPSS (version 20.0; SPSS Inc., Chicago, IL, USA) was used for statistical analysis. Groups were compared using the t test, categorical variables were analyzed using the chi-square test, and p<0.05 was considered significant.

Results

THE DEMOGRAPHIC INFORMATION OF SUBJECTS:

A total of 51 patients with adhesive otitis media were included in this study. ET was performed in 26 patients. The mean age of the patients in the ET group was 36 years (18–50 years). Twenty-five patients underwent MT. The mean patient age was 33 years (20–47 years). There were no significant differences between the 2 groups in terms of age and sex (Table 1).

HEARING AND GRAFT RESULTS:

Otoendoscopic and audiometric evaluations were performed 12 months after surgery. The mean ABG was 24.6 preoperatively and 13.6 postoperatively in the ET group. The mean preoperative and postoperative ABGs in the MT group were 23.6 and 17.8, respectively. Hearing gain in the ABG improved significantly in both groups (p <0.05). When the groups were compared for mean hearing gain in the ABG, the difference was significant (p <0.05). The mean postoperative ABG in the ET group was significantly smaller than that in the MT group. When the postoperative air conduction threshold was evaluated, there was no significant difference between the 2 groups at 4 kHz, whereas a significant difference was observed in the ET group at 0.5, 1, and 2 kHz (Table 2). Postoperative graft failure, otorrhea, and retraction were not observed in any of the patients.

Discussion

Endoscopic and microscopic tympanoplasty are surgical techniques for the treatment of adhesive otitis media. The most challenging aspect of adhesive otitis media surgery is to control the retracted tympanic membrane borders and clean them without leaving any residue. We found that the anatomical and functional results of the endoscopic and microscopic approaches were similar. However, it is essential to highlight that the endoscopic approach exhibits visual superiority, an aspect that is challenging to express statistically.

In tympanic retraction and adhesive otitis media, clear microscopic assessment of the boundaries of the retracted tympanic membrane in the retrotympanum and epitympanum is difficult. External auditory canal curettage, drilling, or scutum curettage may be required to improve visualization. We believe that minimal endoscopic bone removal facilitates visualization and peeling of the retracted membrane adhering to the retrotympanum (Video 2). Bennett et al reported that visualizing the subunits of the middle ear (facial recess, sinus tympani, supratubal recess, and epitympanum) with 0° endoscopes was better than that with microscopy, and this difference was even more pronounced with angled endoscopes [10]. We believe that the membrane adhering to the retrotympanum recesses (facial recess, sinus tympani, posterior sinus and sinus subtympanicus) can be dissected more easily under endoscopic vision (Figures 1–3).

Early retractions are usually clean and observations are sufficient. In more advanced stages, deep retraction may result in infection with keratin deposition. This can lead to ossicular erosion [11]. If the retraction adheres to the middle ear mucosa and ossicular chain, ventilation tube application will be inadequate, and tympanoplasty will be necessary. If the retraction does not extend to the tegmen or antrum, scutum removal is unnecessary [12]. If the retracted membrane adheres to the incudostapedial joint, incus erosion may occur. The pathogenesis of incus necrosis involves decreased blood flow due to pressure of the retracted tympanic membrane. During surgery, the membranes adhering to the ossicles should be carefully dissected, and the epithelium should not be left behind. If the ossicles are excessively manipulated, sensorineural hearing loss can occur [13].

Marchioni et al reported minor intraoperative complications in 34 out of 825 patients who underwent endoscopic ear surgery. Among the 16 patients with chorda tympani damage, 2 had transient facial paralysis, 10 had sensorineural hearing loss, 2 had intraoperative TM rupture, 1 had ossicular chain separation, 1 had a footplate fracture, and 2 had gusher damage [14,15]. In our series, transient facial paralysis was observed in 1 patient, and chorda tympani damage was observed in 1 patient in the ET group. These 2 complications were also observed in the first patients. We believe that complication rates will decrease as we gain experience in this field.

When endoscopic and microscopic ossiculoplasty hearing results were compared in the literature, the hearing gains were found to be similar to those observed in our study. Kuo et al found no significant difference between microscopic and endoscopic tympanoplasty groups in their study of 126 patients [16]. Hsu et al, in a series of 139 cases, reported no significant difference between the microscopic and endoscopic tympanoplasty groups [17]. Zakir et al found no significant difference between microscopic and endoscopic tympanoplasty in terms of overall graft take and ABG closure [18]. In our study, the mean ABG in the endoscopic group was significantly lower than that in the microscopic group. In addition, there were no cases of graft failure in either group at the 12-month follow-up.

Compared with the classic postauricular microscopic approach, TEES has advantages in terms of wide visualization of the surgical field; better evaluation of recesses in the retrotympanum, such as the sinus tympani, posterior sinus, subtympanic sinus and folds, such as the tympanic isthmus and tensor fold; and the absence of a retroauricular incision and soft tissue dissection. Disadvantages include single-handed application, loss of depth sensation, equipment cost, difficulty in bleeding control, and a steep learning curve [19]. We have been performing TEES at our clinic since 2015. In the last 5 years, we have completed surgery of the pars tensa and attic retractions using TEES. Sedat Doğan et al reported longer surgical times for the first 30 TEESs; then durations were similar to microscopic surgeries until 60 procedures; and after 60 cases, the duration of TEES was shorter than that of microscopic surgeries [20]. While the surgical time was longer in our initial procedures, surgical success increased during the subsequent procedures, and the surgical time became considerably shorter.

The limitations of our study are its limited sample size, lack of long-term follow-up, and lack of investigation of the etiology with the patients of isolated pars tensa retraction. A multi-institutional study with several different endoscopic surgeons may be able to provide enough cases to draw more meaningful conclusions on the safety, efficacy, and audiometric outcomes of endoscopic tympanoplasty in adhesive otitis media.

Conclusions

The endoscopic approach for tympanic membrane retractions and adhesive otitis media has both advantages and disadvantages over the microscopic approach. The advantages of this approach include a wide panoramic view, magnification without loss of resolution, not always requiring external auditory canal curettage or canalplasty, no retroauricular incision, and a short surgical time. The disadvantages of this technique include single-handed application, loss of depth perception, high equipment cost, difficulty in bleeding control, and a steep learning curve. For tympanic membrane retraction with a suitable external auditory canal, the endoscopic approach is the preferred method for preventing postoperative morbidity.