A Prospective Study of the Effect of Cochlear Implantation on Tinnitus

Previous studies have shown diverse and sometimes even contrary results concerning the effect of cochlear implantation on tinnitus and the factors that can influence this effect. The aim of this prospective questionnaire study was to determine the effects of cochlear implantation on tinnitus and explore which factors can influence the effect of cochlear implantation on tinnitus. Forty-four of the patients implanted in our hospital returned 2 questionnaire packages, i.e., one before the cochlear implantation and one 6 months after implantation. Before implantation, 66% of the patients experienced tinnitus. This study shows that cochlear implantation could help to reduce tinnitus and the tinnitus handicap in at least 28% of the patients with preoperative tinnitus. In 72% of the patients the tinnitus remained after implantation. None of the patients developed tinnitus after implantation. A shorter duration of tinnitus prior to implantation, a more fluctuating type of tinnitus, a higher tinnitus handicap prior to implantation, and a round-window surgical approach might have a positive influence on the effect of cochlear implantation on tinnitus, but further research is necessary to confirm these findings. © 2019 The Author(s) Published by S. Karger AG, Basel Introduction Tinnitus is a very common problem that has existed for centuries; the oldest known written report dates back to the ancient Egyptians and Mesopotamians [Stephens, 1984]. The prevalence of tinnitus in the general population ranges from 5 to 43%, with 12–30% of these patients suffering from tinnitus that lasts for more than 5 min at a time [McCormack et al., 2016]. Of the patients who visit self-help groups because of their tinnitus, 30–42% are willing to use devices if this will significantly reduce their tinnitus, 52–62% are willing to use medication for tinnitus reduction, and 13–38% are even willing to undergo invasive procedures to obtain a significant tinnitus reduction [Tyler, 2012]. Although tinnitus is a phenomenon that has existed for centuries, its exact cause is still not known. There are several hypotheses about the cause of tinnitus. Many hypotheses have in common that central neural mechanisms play a key role in its development. Most of these hypotheses state that tinnitus is caused by maladaptive plastic changes in the central auditory pathways as a reaction to peripheral hearing loss [Cacace et al., 2016]. Within the population of cochlear-implant candidates, the prevalence of tinnitus is between 66 and 86% [Hazell et al., 1995; Quaranta et al., 2004; Baguley and This article is licensed under the Creative Commons AttributionNonCommercial-NoDerivatives 4.0 International License (CC BYNC-ND) (http://www.karger.com/Services/OpenAccessLicense). Usage and distribution for commercial purposes as well as any distribution of modified material requires written permission. Effects of Cochlear Implantation on Tinnitus 357 Audiol Neurotol 2018;23:356–363 DOI: 10.1159/000495132 Atlas, 2007; Andersson et al., 2009; Kompis et al., 2012]. This high prevalence is consistent with the fact that people with hearing impairment are more likely to suffer from tinnitus [Han et al., 2009]. Cochlear implantation is associated with a postoperative reduction of tinnitus loudness and awareness [Ruckenstein et al., 2001; Di Nardo et al., 2007]. Previous studies have shown a positive effect of cochlear implantation on both tinnitus prevalence and the handicap it causes in up to 93% of patients [Ruckenstein et al., 2001; Pan et al., 2009; Kloostra et al., 2015]. Unfortunately, cochlear implantation can also have a negative effect on tinnitus. In some studies, participants have experienced deterioration of their tinnitus or have even developed tinnitus [Kompis et al., 2012; Kloostra et al., 2015; van Zon et al., 2016]. According to previous studies, the number of participants that experience deterioration of tinnitus after cochlear implantation is between 4 and 26% [Kompis et al., 2012]. As cochlear implantation can be of value in reducing both the prevalence of tinnitus and the tinnitus handicap in patients who suffer from severe hearing problems, the aim of this prospective questionnaire study was to determine the effects of cochlear implantation on tinnitus and explore which factors can influence the effect of cochlear implantation on tinnitus. Previous studies have shown very diverse results concerning the effect of cochlear implantation on tinnitus and the factors that can influence this effect [Ruckenstein et al., 2001; Pan et al., 2009; Kompis et al., 2012; Kloostra et al., 2015; van Zon et al., 2016]. For our study, we used several validated questionnaires that enabled us to have a broad view of the effect that cochlear implantation might have on patients who suffer from tinnitus. We also used tinnitus handicap questionnaires to determine how the presence of tinnitus influences daily life in cochlear implant patients. We used a hearing handicap questionnaire to establish whether cochlear implantation, besides improving phoneme scores, also improves hearing abilities in daily life. Last, we included an anxiety and depression questionnaire to assess the influence of tinnitus and hearing loss on these feelings. Materials and Methods Procedure and Inclusion A total of 63 successive CI candidates from the Cochlear Implant North Netherlands (CINN) patient database were asked to participate in this questionnaire study on tinnitus. All of the patients were implanted in the University Medical Center Groningen (UMCG) between 2010 and 2013. All of them were 18 years or older at the time of this study and gave their written, informed consent. As concluded by the Medical Ethics Committee of the UMCG, this study it not subject to Dutch law on Medical-Scientific Research on Humans (Wet Medisch-wetenschappelijk Onderzoek met Mensen, WMO). This study was conducted in accordance with the Declaration of Helsinki and applicable Dutch laws. Surgical Techniques Two surgical approaches, i.e., the round-window insertion technique and the cochleostomy technique, were used for cochlear implantation. In the first technique, electrode insertion is done through the round-window aperture. In the second technique, electrode insertion is also done through the round-window aperture, but the round window is enlarged using a small drill. It is thought that this round-window insertion technique causes less damage to the cochlea. Most commonly, surgeons use the cochleostomy technique instead of the round-window insertion technique due to the sort of electrode that was implanted. The CI422 electrode can be placed using the round-window insertion technique and the CI24RE electrode and the Advanced Bionics electrode can only be placed using the cochleostomy technique. In fewer cases, the reason for using the cochleostomy technique is that the position of the facial nerve makes it impossible to reach the round window. Measures In this prospective study, we sent the participating patients 2 questionnaire booklets. The first booklet was sent when the participant agreed to undergo cochlear implantation. It was thus completed weeks to a couple of months prior to the implantation. This booklet consisted of questions about the preoperative situation. The second booklet was completed 6 months after the patient was implanted and consisted of questions about the postoperative situation. Each booklet contained several questionnaires about tinnitus characteristics, depression/anxiety, and hearing status. Also, the UMCG anamnestic tinnitus questionnaire was included, which contained several questions about the characteristics of the tinnitus and the influence of the CI on tinnitus perception. Further information about audiological tests, the date of implantation, the surgery method, and the processor type was collected from the clinical files of the patients. Questionnaires Abbreviated Profile of Hearing Aid Benefit We used the translated and validated Dutch version of the Abbreviated Profile of Hearing Aid Benefit (APHAB). The APHAB questionnaire assesses hearing ability and discomfort [Cox and Alexander, 1995]. It contains 24 questions that are divided into the following 4 subscales: ease of communication (EC), background noise (BN), reverberation (RV), and aversiveness (AV). The EC scale describes the ability to understand people in various situations. The BN scale describes how background noise affects the ability to understand conversations. The RV scale describes the influence of reverberation/echo in rooms on hearing ability. The AV scale describes the discomfort caused by unpleasant sounds. All of these subscales contain 6 items and the patient is asked to rate all of the questions according to how often situations occur. The 7 different gradations are as follows: always (99% of the time), almost always (87%), generally (75%), half the time (50%), occasionally (25%), seldom (12%), and never (1%).