Recent Advances in Cochlear Implant: A Systematic Review

Abstract

Background: Cochlear implants are implantable device designed to mimic the function of a healthy inner ear. They replace the function of damaged sensory hair cells inside the inner ear to help provide clearer sound than what hearing aids can provide. The patients with cochlear implants benefit from cutting-edge sound processing technology that analyses the surrounding noise and automatically modifies the processors settings for optimum hearing. Advances in the programming of sound processing algorithm have improved the user’s abilities to hear sounds other than speech such as music. This systematic review aims to provide knowledge about the recent advances in cochlear implant instrumentation and mapping strategies. Methods: A comprehensive literature search was conducted across major electronic databases, including PubMed, Google Scholar, Science Direct, ProQuest and Psynet. Studies published between 2012 to 2023 were included if they focused on latest technologies on cochlear implant in terms of instrumentation and mapping strategies. Relevant articles were selected, and their quality was assessed using with Preferred reporting Items for Systematic review and Meta-Analysis (PRISMA). Results: The initial search yielded 3,102 articles, of which 12 met the inclusion criteria. The included studies highlighted the new trends in instrumentation and mapping strategies of cochlear implant. The instrumentation includes the innovative technologies such as SCAN, wireless technology, sound processors, smart application for iPhone and android users and development in electrodes and surgical techniques. In considering, the mapping strategies, evaluating T level, C level and dynamic range which assisted in studying comfortability level of cochlear implant while facing challenging environment composed of speech and other sounds. Conclusion: The findings of this systematic review underline the significance of recent development in cochlear implant. The results from all 12 articles had shown tremendous improvement in recognizing speech and improving quality of life for individuals with sensorineural hearing loss. In addition to that all literature had shown that these new technologies made the user’s seamless and effortless while handling the cochlear implant.

Introduction

I. INTRODUCTION

Sensorineural hearing loss is common type of hearing loss that occurs around the world. According to World Health Organization by 2050 nearly 2.5 billion people are projected to have some degree of hearing loss and at least 700 million will require hearing rehabilitation. The cochlear implant serves a solution for sensorineural deafness and has created a paradigm in the treatment of sensorineural hearing loss. It will have a great impact in brief time. In less than four decades, the cochlear implant has progressed from the first attempt to elicit hearing via direct electrical stimulation of the auditory nerve to a commercially available device that has restored varying degrees of   hearing to thousands of deaf patients.The CI has improved and enhanced to restore hearing through years with the research and developmental activities of manufacturers and audiologist. The sound processor is the one that has undergone continuous modification as it started from the bodyworn type to a single unit processor. Signal processing strategies have seen changes over time which started with simultaneous multichannel analog stimulation to channel specific sequential stimulation that resulted in power consumption and better hearing experience by the CI users. Due to recent advancement, there are MRI compatible implant magnet would assist in trouble free MRI procedures without the need for the surgical removal of the magnet. 

A. Need For The Study

Cochlear implant is the most powerful sensory device which helps in reestablishing hearing. CI has undergone modifications in surgical as well as in terms of technology. In considering, speech perception CI is able to deliver best outcome in research and development of sound processor, electrode array, microphone etc. Hence it is required to review through various studies conducted around the world.

II. METHEDOLOGY

A. Aim

To systematically review the outcomes of literatures that used in recent advances in cochlear implant.

B. Objectives

1. To provide a thorough overview of recent advances in cochlear implant.
2. To understand the patient’s experience derived from modern technologies in cochlear implant.
3. To provide insight about significance of cochlear implant

C. Review Question

The current review of studies was performed with the following review question: “What are the recent advances in cochlear implant instrumentation and mapping strategies?”

1. Criteria For Inclusion Of Literature

a. Literature must be from 2012 to 2023.

b. Studies available in English.

c. Studies contained original data addressing the review/clinical questions.

2. Criteria For Exclusion Of Literature

a. Repeated or duplicate studies.

b. Studies with unclear findings.

c. Studies which are not within inclusion criteria.

D. Search Process

The review was conducted in accordance with Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) standards. Key words like “Cochlear Implant, Speech Perception, Sound Processor, Surgery, Electrode Array, Mapping were the search terms. These search terms were used to look up literature across several databases. PubMed, Google Scholar, Science Direct, ProQuest and PsyNet databases were used to find out the related articles for the review. The PRISMA flow chart has four steps: discovering the articles, screening the articles that have been found, determining their eligibility and choosing the articles for the study. These concluding articles were chosen as qualitative studies that met the requirements for inclusion in the current investigation.

E. Data Extraction

The titles, abstracts and/or research methods that the search techniques returned were screened to identify the studies that met the inclusion and exclusion criteria. The full text of the potential studies was then obtained and reviewed to ascertain their eligibility. A table created for the pre study was used to retrieve the data from the chosen research. The following information was extracted: study population, methodology, participant demographics, evaluation methods and treatment outcome. Data on the eligible articles that met the inclusion and exclusion criteria were also collected including information on the year of publication, kind of publishing, study design, research type, research emphasis, study origin and author details with affiliation.

III. RESULT AND DISCUSSION

A. Selection Of Literature for Systematic Review

Identification of the articles relevant to the current topic was important step and using key words to the different electronic databases, 3102 records were identified. Different database included Google scholar (n=2002), ProQuest (n=498), PubMed (n=450), Research Gate (n=102) and others (n=50). From the total identified articles (3,102), duplicate articles (1,301) were excluded and remaining 1,801 articles were screened for the study. The articles (1,511) that did not match the review topic were also excluded. Remaining 290 articles were taken into consideration for further process and 59 articles were not able to be retrieved and were also not included. 231 articles were assessed for eligibility for inclusion in the current review. Articles that were published (169) earlier than 2012 were also not included. Article published after 2012 (n=50). Finally, only 12 articles fully matched our eligibility criteria and were selected for the study.

These twelve articles are the latest research papers that are published in different journals of audiology between 2012 to 2023. These all papers include the recent advances in cochlear implant instrumentation and mapping strategies.

IV. STUDY DESIGN AND CHARACTERISTICS

Papers selected for the current review were all pre and post-test research design depending on comparative, observational, training survey and experimental study (Table 1). What are the recent advances in cochlear implant instrumentation and mapping strategies are listed in Table 1. Zhou, Wang, Zheng, Yu and Meng (2020) included 19 participants in which 11 were 2 weeks experienced CI users and 8 were 5-10 min CI users. Ceulaer, Pascoal ,Vanpoucke, Govaerts (2017), included a group of 13 adult CP900 recipients participated. Chang, Jung, Sun, Hung, Hsu, Jen, Chiu, Ting; Yu, Hui, Wu, Hung (2022), included 20 adult CI recipients. Shaul, Chanan, Weder, Stefan, Tari, Sylvia, Marc, Leary, Stephen, Briggs, Robert (2020), included all patients receiving the CI532 implant before June 2018. McJunkin, Jonathan, Durakovic, Nedim, Herzog, Jacques, Buchman, Craig (2018), included 117 adult CI patients.

Valimaa, Kunnari, Sar, Aarnisalo, Dietz, Aarno, Hyvarinen, Antti, Laitakari, Jaakko, Mykkanen, Sari, Rimmanen, Satu,Salonen, Jaakko, Sivonen, Ville, Tennila, Tanja, Tsupari, Teija, Vikman, Sari, Virokannas,Nonna,Nevala, Tolonen, Kaisa, Tuohimaa, Krista, Lopponen, Heikki (2022),  included the participants comprised 56 children: 28 children in the BiHA group and 28 children in the BiCI group. Kurz, Rak, Hagen (2022), included twenty adult SONNET users were fitted with the SONNET 2 audio processor was sample size. Kolberg, Sheffield (2015), included total of 11 adults with Advanced Bionics CIs were recruited. MacPhail, Connell, Totten, Gray, Pisoni, Yates, Nelson (2022), included slim lateral wall electrode (SLW) 52 and patients with slim modiolar electrode (SME) 37. Dincer, Alessandro, Ballantyne, Portanova, Greco, Mancini (2022), included Eleven post lingually deafened bimodal listeners. Perreau, Tyler, Frank, Watts, Mancini (2021), included 14 using the ReSound Tinnitus Relief app to evaluate its acceptability and effectiveness in reducing their tinnitus. Incerti,  Ching, Hou, Buynder, Flynn and Cowan (2018), included 161 children. Figure 1: shows the diagram that illustrates the PRISMA (Moher, Liberati, Tetzlaff & Altman, (2020), process of identification, screening and selection of the articles for the present study.

Conclusion

The current systemic review focussed on recent trends in instrumentation and mapping strategies of cochlear implant. The instrumentation includes the innovative technologies such as SCAN, wireless technology, sound processors, smart application for iPhone and android users and development in electrodes and surgical techniques. In considering, the mapping strategies, evaluating T level, C level and dynamic range which assisted in studying comfortability level of cochlear implant while facing challenging environment composed of speech and other sounds. Through past decades cochlear impl