Discussion
cognitive impairment, ’, moderate-to-profound hearing impairment, mild-cognitive impairment, hearing loss, hearing impaired
HEARING LOSS, HEARING IMPAIRED
Cochlear implantation is an effective treatment for moderate-to-profound hearing impairment, and as such implant candidacy has expanded in recent years to include a greater number of older adults [As demonstrated in previous studies, we report here a strong correlation between the maximum comfort levels in a cochlear implant MAP (here, M-Levels) when determined behaviourally compared with those determined with an objective, eSRT based approach. While the global charge rates of the two approaches were not significantly different, the behavioural MAPs featured higher M-Levels along the mid-basal electrodes 6–8 compared with the eSRT MAPs. The cause of this mid-basal enhancement is unclear, and is contrast with prior studies reporting similar, higher behavioural thresholds (Asal A potential explanation for higher behavioural thresholds is the identification that behavioural MAP thresholds tend to increase over the implant users experience with the device after implantation, only stabilizing over 24 months of use [The novel finding in the present work is in the comparison of MAP and speech outcomes with cognitive state, using a variant of the MoCA test appropriate for the hearing impaired (MoCA-HI). In particular, MoCA-HI scores correlated negatively with BKB-SIN scores [This appears to be the first study investigating the sound quality perception of eSRT-based MAPs in adult CI recipients. In this study, MAP sound quality was measured using the HISQUI, which evaluated how well everyday listening tasks were completed with the CI after each two-week trial. Statistically similar mean overall sound quality scores were reported with both methods. As a validated tool of self-perceived CI auditory benefit [The majority of study participants verbally reported a personal preference of the eSRT-based MAP as it provided improved clarity. A potential explanation for the discrepancy in participant preference and sound quality scores may be that the sound quality outcome measure was not sensitive enough to discern subtle clarity differences between MAPs. For example, Question 7 asks participants to rate how well they understand the voices of unfamiliar people over the phone on a 7-point Likert scale from ’Always’ to ’Never’. For CI recipients, phone-related tasks are typically difficult [A potential limitation in the present work is the limited trial duration for each MAP, over a period of 2 weeks. This may not have been sufficient time for the participants to acclimatise to each MAP, which would obscure the potential benefits or drawbacks of the objectively-determined approach. While the optimal trial duration is unclear, prior work has identified experience-related changes to the brain over 8- to 12-weeks following CI programming procedures, a substantially longer time period of acclimatization [A second limitation is the relatively small number of patients with ≤ 23 scores on the MoCA-HI test. This results in a limited population to test the effect of cognitive impairment on programming approaches, and although differences between MoCA-HI score and BKB-SIN result were clear in the present work, suggesting sufficient variability in the measure, an effect of mild-cognitive impairment on programming outcomes may be obscured by the limited patient number. This is further compounded by the wide variability in patient demographics, including age, years of hearing loss and BE3PTA. This was a stated goal of the study, as this variability was chosen as a possible way of capturing differences between MAP outcomes that may have been present only in some subpopulations. However, this raises the possibility of introducing too much variability to enable the detection of real differences in the population.