The natural progression of low-frequency hearing loss in patients who meet hybrid implant system candidacy criteria

Objectives/hypothesis: To investigate the natural progression of hearing loss in patients with high-frequency hearing loss whose audiograms met the criteria for a hybrid cochlear implant (CI).

Study design: Retrospective database review.

Methods: We retrospectively identified patients who met the criteria for a hybrid CI from our audiometric database. We also recorded the etiology of hearing loss in each patient and excluded patients with retrocochlear etiologies, those age <6 years, duration of observation <1 year, or those with a mixed or conductive hearing loss. We calculated the pre-CI progression of residual low-frequency (LF) hearing level in decibels per year and investigated the risk factor of the progression of hearing loss.

Results: A total of 1,083 ears of 944 patients were included in this study. The average rate of hearing loss progression for all etiologies was 1.70 ± 0.10 dB/yr at an average of 250 Hz, 500 Hz, and 1 kHz in the affected ear(s). The progression of hearing loss was 5.0 ± 0.93 dB/yr in patients with Meniere's disease and 3.5 ± 0.76 dB/yr in those with autoimmune disease, both of which were significantly faster than progression rates in other etiologies. In patients with idiopathic, genetic/hereditary, and congenital hearing loss, the progression of hearing loss was 1.46 ± 0.10 dB/yr. Patients with steeply sloping hearing loss experienced significantly faster progression in the ipsilateral ear compared to patients with another audiometric type.

Conclusions: It is suggested that Meniere's disease, autoimmune-mediated inner ear disease, and steeply sloping hearing loss in the ipsilateral ear are risk factors for faster progression of residual LF hearing level.

Level of evidence: 4 Laryngoscope, 130:1299-1303, 2020.