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This paper is a single-centre review of adult cochlear implants in patients with preserved low-frequency hearing, focusing on the outcomes at 10 months post-implantation, and the rates of electroacoustic stimulation actually used in this group of patients. The centre identified 52 patients (53 implants) who underwent cochlear implantation using standard length electrodes (Medel, Cochlear and Advanced Bionics) and a ‘hearing-preservation’ technique via a minimally traumatic round window insertion. This study acknowledges the difficulties comparing hearing-preservation outcome data between different centres due to a lack of consensus previously, but in this study they have employed the 2018 HEARRING group classification definitions (complete >75%, partial 25-75%, minimal <25%). The results revealed that 30% had complete hearing preservation, 35.8% partial hearing preservation, and 20.8% minimal hearing preservation. In 12 patients there was no hearing preservation post-implantation. The overall mean hearing preservation of 52.9% is less than that identified in paediatric patients treated in the same centre (55.5%). There was a statistically significant increase in hearing thresholds comparing audiograms at three months (89.47dB) and 12 months (94.98dB) which the authors propose may be related to disease progression or postoperative changes (possibly fibrosis) to the cochlear environment. Only two patients in this study went on to use electroacoustic stimulation and they were patients with low frequency hearing in the normal-to-mild range. The main message from these results appears to be that patients who have preserved low-frequency hearing prior to cochlear implantation, and undergo technically successful hearing-preservation surgery, may not obtain the functional benefit of that preserved natural hearing, particularly as time goes on. This is important in preoperative counselling of patient expectations, and an important area for further study.

Hearing Preservation Outcomes With Standard Length Electrodes in Adult Cochlear Implantation and the Uptake of Electroacoustic Stimulation.
Harrison L, Manjaly JG, Ellis W, et al.
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Aileen Lambert

Great Ormond Street Hospital, London, UK.

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