Intraoperative auditory brainstem response monitoring during semicircular canal plugging surgery in treatment of Meniere's disease

Background Three semicircular canal plugging (TSCP) is an optimized treatment for intractable Meniere's disease (MD). However, 20-30% of patients experience hearing loss after TSCP, for reasons that remain unclear. Objective To evaluate hearing loss resulting from TSCP. Subjects and methods This study included 12 patients, which were diagnosed with definite MD and consented to TSCP surgery. Intraoperative auditory brainstem response (ABR) was monitored in each surgical procedure. Results After opening the mastoid cavity, the ABR threshold increased to 77.08 +/- 9.88 dB nHL. The ABR threshold almost recovered to preoperative levels, to 68.33 +/- 7.78 dB nHL, after completing TSC outlining. Exposure of three semicircular canal 'blue lines' had little effect on ABR threshold. The most prominent change on hearing loss was observed after mastoid outlining, when 41.67% of patients showed hearing loss >= 10 dB nHL. None of the patients showed a threshold shift >= 10 dB nHL following the last step. Conclusions TSCP operation itself caused little hearing damage. Significance Ruled out hearing loss as a result of the surgery itself. The reason why 20-30% of patients showed hearing loss in 2-year follow-up visit was not clear, although it may be due to serous fibrous labyrinthitis.