Frequency-dependent hearing outcomes with or without preservation of intact ossicular articulations.

Abstract

To determine the frequency-specific benefits of ossicular chain preservation compared to performing disarticulations and reconstructions in transmastoid facial nerve decompression surgery in patients with an intact ossicular chain. A retrospective chart review (January 2007 and June 2018) of patients undergoing transmastoid facial nerve decompression on the intact middle ear for severe facial palsy at a tertiary referral center. Surgery was performed with ossicular chain disarticulation on an as-needed basis using either ossicular chain preservation (without ossicular disarticulation), incudostapedial separation, or incus disarticulation technique. Hearing outcomes were assessed. The 108 patients were included in this study. Among these, 89 patients underwent ossicular chain preservation, 5 underwent incudostapedial separation and 14 underwent incus repositioning. The proportion of patients with a change in the 4-frequency air conduction pure-tone average of less than 10dB was 91%, 60%, and 50%, respectively, for the three surgical techniques; these were significantly different (Fisher's exact test, p < .001). Frequency-specific analysis showed that air conduction was significantly better following the ossicular chain preservation technique compared with the incus repositioning technique at stimulation frequencies lower than 250 Hz and higher than 2000 Hz, and compared with the incudostapedial separation technique at 4000 Hz. Analysis of biometric measures determined on CT images suggested that the feasibility of the ossicular chain preservation technique correlates with incus body thickness on coronal CT images. Ossicular chain preservation is an effective approach for hearing preservation in transmastoid facial nerve decompression or similar surgical procedures.