Long-term outcomes of stapes surgery.

OBJECTIVE: Hearing improvement following stapes surgery is generally good; however, we sometimes encounter patients where hearing loss gradually progresses over the long term. In this study, we investigated the causes of hearing loss in these cases. METHODS: A total of 30 ears from 23 patients, who underwent stapes surgery at Kitasato University Hospital from 2001 to 2021 and were followed up for ≥5 years, were included in the study. Changes in air conduction (AC) and bone conduction (BC) thresholds were measured, and hearing evaluation was performed by calculating the air-bone gap (ABG) at the mean of 4 frequencies. Cases with a postoperative ABG of ≤10 dB at 6 months after surgery were classified into the following groups according to their hearing changes at 5 years after surgery: Group A (no ABG increase of ≥10 dB and no AC threshold increase of ≥10 dB) and Group B (an ABG increase of ≥10 dB and an AC threshold increase of ≥10 dB). In groups A and B, we examined factors affecting long-term postoperative results. In addition, the patients who underwent reoperation were examined. RESULTS: The AC thresholds 6 months and 5 years after surgery decreased significantly compared with those before surgery (p  <  0.01); however, the BC thresholds 6 months and 5 years after surgery did not vary significantly from those before surgery (p  >  0.05). Group A included 16 ears from 13 patients (53.3%), and Group B included 3 ears from 3 patients (10.0%). There were no significant differences in age, sex, surgical method, piston type, piston length, presence of incudostapedial joint subluxation, computed tomography findings, and preoperative ABGs between groups A and B (p  >  0.05). A total of 6 reoperations were performed in 3 ears from 3 patients, and there were 5 operations with the platinotomy hole to be closed by bone regrowth and 3 operations with the narrowed long process of the incus. CONCLUSION: In 10.0% of the patients who underwent stapes surgery, the ABG improved 6 months after surgery; however, the AC threshold and ABG increased 5 years after surgery. Our findings suggested that piston displacement and the platinotomy hole to be closed by bone regrowth are possible causes of hearing loss in cases where hearing loss progresses in the long term after stapes surgery.