A comparative study of changes in audiological characteristics when using endoscopic and microscopic stapes surgery in patients with otosclerosis

BACKGROUND: Endoscopic stapes surgery (ESS) is widely used to treat patients with otosclerosis, and accumulating evidence demonstrates that endoscopic stapedotomy is feasible and has similar, and often even better, audiological outcomes compared with microscopic stapedotomy. There is a lack of studies on comparisons of ESS and the audiological outcomes of ESS and microscopic stapes surgery (MSS). Therefore, in the present study, we investigated these to figure out if ESS could be a reasonable alternative treatment for otosclerosis patients. METHODS: This was a cohort study of 65 patients with otosclerosis who underwent ESS (n=30) or MSS (n=35) between 2017 and 2021, whose diagnoses were mainly based on a history of progressive conductive or mixed deafness over 25 dB in the range of 0.25–4 kHz. Preoperative and postoperative audiological evaluation, including air-conduction (AC), bone-conduction (BC) and air-bone gap (ABG), was carried out using pure-tone audiometry and performed within 4 weeks before surgery and from 1–14 months after surgery. RESULTS: Thirty ESS and 35 MSS patients were included. There were no significant differences in preoperative and postoperative pure-tone average AC (AC-PTA), BC-PTA, and ABG-PTA between the 2 groups. Postoperative ABG ≤10 dB was found in 8 ESS patients (60%) and 15 MSS patients (43%) (P=0.168). AC and ABG changes in the low-frequency (LF) and mid-frequency (MF) ranges were greater than those in the high-frequency (HF) range for both groups (P<0.05). Although auditory changes between the 2 groups were similar, MSS appeared to have a better BC-PTA compared with ESS (P=0.049). Shifts in ABG and BC were linearly related to preoperative ABG and BC in both groups, and shifts in AC were linearly related to preoperative AC in the ESS group (P<0.05). CONCLUSIONS: ESS had a similar audiological outcome compared with MSS, and LF and MF hearing improved to a greater degree than HF hearing in both groups in our study. Based on the linear regression analysis in our study, preoperative ABG-PTA was proved to be the most efficient surgical indicator for both types of stapes surgery for patients with otosclerosis.