Endoscopic stapes surgery: our clinical experience and learning curve

Objective: The purpose of this study was to assess the audiological results and surgical outcomes of patients who underwent endoscopic stapes surgery (ESS). Methods: This study included 40 consecutive patients who underwent stapes surgery with a fully endoscopic approach at Dr. Ersin Arslan Research and Training Hospital between January, 2015 and April, 2018. We retrospectively evaluated the patients’ audiological results, surgery duration, surgical findings, and complications. To assess the learning curve, participants were divided into two groups based on their date of surgery: first twenty patients (FTPs) and last twenty patients (LTPs). Results: The mean operative duration was 43.4 ± 11.3 minutes among all patients, 51.5 ± 9.2 minutes among FTPs, and 35.3 ± 3.9 minutes among LTPs (p < 0.05). The average air-bone gap (ABG) values were 33.7 ± 8.5 dB preoperatively and 8.7 ± 6.9 dB postoperatively (p < 0.05). The incudostapedial joint (ISJ) of 24 patients (60%) and the stapes footplate of 13 patients (32%) were directly visible without requiring bone curettage. None of the patients experienced major complications, such as facial paralysis or sensorineural hearing loss. Conclusions: The present results show the surgical and audiological outcomes of exclusively endoscopic transcanal stapes surgery, indicating the advantages, limitations, and learning curve for this procedure. ESS appears to be a safe and effective alternative technique that produces reasonable surgical and functional outcomes. Conflict of Interest: The authors declare that they have no conflict of interest. Informed consent: Informed consent was obtained from all individual participants included in the study. 05-Gulsen.indd 281 12/12/19 18:01 282 S. Gulsen et al. of 11 cm. Images were acquired using endoscopes connected to a camera head (Karl Storz, Germany), and transferred to a high-definition monitor located in front of the surgeon. Illumination was provided by an LED light source (Karl Storz, Germany). To reduce bleeding, the external auditory canal was infiltrated with lidocaine and adrenaline solution (Jetokain®, Adeka, Samsun, Turkey). All patients received a polytetrafluoroethylene (PTFE) prosthesis loop (Xomed, Jacksonville, Fla, USA), with a shaft thickness of 0.4 mm, and a length of 4, 4.5, 4.75, or 5 mm based on the distance between the long process of the incus and footplate. In all patients, stapes surgery involved the following steps performed in the same order (Figure 1). (1) Elevation of the tympanomeatal flap. (2) Accessing the middle-ear space by separating the fibrous annulus from the tympanic sulcus. (3) Removal of the scutum (while preserving the chorda tympani nerve) to expose the ISJ and footplate, when necessary. (4) Confirming stapes fixation and ensuring the mobility of the incus and malleus with gentle palpation of ossicles. (5) Separating the ISJ, cutting the stapedial tendon, and removing the stapes superstructure. (6) Evaluation of the distance between the incus long arm and footplate utilizing the measuring rod. (7) Small fenestration of the footplate using 0.4-mm, 0.5-mm, and 0.6-mm perforators, respectively. (8) Insertion of the PTFE prosthesis, and stabilization by placing the gelfoam around the footplate. And finally, (9) restoring the tympanomeatal flap to its original position and packing the external ear canal with gelfoam. Preoperative and postoperative pure-tone audiometry (PTA), surgical findings, complications, and surgery duration were recorded to the patients’ personal files, and retrospectively analysed. Air conduction (AC) and bone conduction (BC) thresholds at frequencies of 0.5, 1, 2, and 4 kHz were measured preoperatively and six months postoperatively. The preoperative and postoperative air-bone gap (ABG) values were calculated, using the averages from the frequencies 0.5, 1, 2, and 4 kHz. To assess the ESS learning curve, patients were divided into two groups based on the date of surgery: first twenty patients (FTPs; n = 20) and last twenty patients (LTPs; n = 20). The parameters used to evaluate the learning curve were operative times and auditory improvements. Statistical analysis was performed using the statistical package for social science (SPSS) microscopic transcanal approach is inconvenient, an endoscope can facilitate stapes surgery and usually enables transcanal surgery. Frequently encountered problems, particularly with the postauricular and endaural approaches, include postoperative pain, sensation of numbness at the auricula, and dysgeusia. With the microscopic transcanal approach, scutum curettage is performed to obtain an adequate view of the incudostapedial joint (ISJ) and footplate, which may result in incus dislocation and chorda tympani injury. In this context, endoscope use in stapes surgery has many advantages, including excellent exposure of stapedial structures and the ISJ, less need for bony resection (canaloplasty and scutum removal), chorda tympani preservation, a panoramic view of the middle ear structures, minimal invasiveness, and almost no postoperative pain. Despite these advantages, endoscopic techniques are limited by the lack of 3-D vision, requirement of experience, prolonged learning curve compared to the microscopic technique, and necessity of performing single-handed surgery. In the present study, we aimed to evaluate the advantages, limitations, and learning curve of the endoscopic transcanal technique for stapes surgery, along with the surgical and functional results. Materials and methods The present study included 40 consecutive patients (23 females and 17 males) who underwent fully endoscopic stapes surgery (ESS) at Dr. Ersin Arslan Training and Research Hospital (tertiary referral centre) between January 2015 and April 2018. The inclusion criteria were having a conductive type of hearing loss without ear discharge, type A tympanogram results, and a poor stapedial muscle reflex. Temporal bone computed tomography was obtained for all patients to determine whether they had any other middle ear pathology blocking sound transmission. The duration of postoperative follow-up ranged from 6 to 12 months (mean, 8.2 months). Informed consent was obtained from all participants, and this study was approved in advance by the local ethical committee. All cases involved primary stapes surgery, performed by the same surgeon. ESS was performed using rigid endoscopes (Karl Storz Endoscopes, Tuttlingen, Germany), with angles of 0 and 30 degrees, diameter of 2.7 mm, and length 05-Gulsen.indd 282 12/12/19 18:01 Endoscopic stapes surgery 283 that postoperative ABG decreased to ≤10 dB in 27 patients (67.5%), decreased to 10-20 dB in 12 patients (30%), and remained >20 dB in 1 patient (2.5%) (Table 2). While the mean preoperative ABG was 33.7 ± 8.5 dB (range: 22-55 dB), the mean postoperative ABG decreased to 8.7 ± 6.9 dB (range: 0-22 dB), showing a statistically significant postoperative ABG improvement (p < 0.05). Moreover, separate analyses of the FTPs and LTPs showed that these groups significantly differed in terms of auditory improvement (Table 1). The average postoperative ABG values were 11.8 dB among FTPs, and 4.9 dB among LTPs (p < 0.05). The overall mean auditory gain (preoperative mean ABG value minus postoperative mean ABG value) was 25 ± 5.2 dB, whereas the postoperative auditory gains were 21.9 dB among FTPs and 28.6 dB among LTPs (p < 0.05). The mean operative time was 43.4 ± 11.3 min (range: 30-75) among all patients, 51.5 ± 9.2 min (range: 41-75 min) among FTPs, and 35.3 ± 3.9 min (range: 30-42 min) among LTPs (Table 1). The mean operative time significantly differed between the FTPs and LTPs (p < 0.05). Moreover, ESS software version 22. Continuous variables were reported as mean ± standard deviation. Preoperative and postoperative air-bone gaps and operative times were compared using the paired sample t-test and independent t-test, respectively. The chisquare test (post-hoc power analysis, 72.41%) was utilized to compare FTPs and LTPs with regards to complication rates, including dysgeusia, pain, and dizziness. A p value < 0.05 was considered to indicate statistical significance.