Angular Electrode Insertion Depth and Speech Perception in Adults With a Cochlear Implant: A Systematic Review

• Published in: Otology & neurotology Vol. 40; no. 7; pp. 900 - 910
• Main Authors: Heutink, Floris, de Rijk, Simone R, Verbist, Berit M, Huinck, Wendy J, Mylanus, Emmanuel A M
• Format: Journal Article
• Language: English
• Published: United States Copyright by Otology & Neurotology, Inc. Image copyright Wolters Kluwer Health/Anatomical Chart Company 01-08-2019; Lippincott Williams & Wilkins
• Subjects: Adult; Cochlea - surgery; Cochlear Implantation - methods; Cochlear Implants; Deafness - surgery; Humans; Speech Perception - physiology; Treatment Outcome
• ISSN: 1531-7129; 1537-4505
• DOI: 10.1097/MAO.0000000000002298

OBJECTIVE:By discussing the design, findings, strengths, and weaknesses of available studies investigating the influence of angular insertion depth on speech perception, we intend to summarize the current status of evidence; and using evidence based conclusions, possibly contribute to the determination of the optimal cochlear implant (CI) electrode position.
DATA SOURCES:Our search strategy yielded 10,877 papers. PubMed, Ovid EMBASE, Web of Science, and the Cochrane Library were searched up to June 1, 2018. Both keywords and free-text terms, related to patient population, predictive factor, and outcome measurements were used. There were no restrictions in languages or year of publication.
STUDY SELECTION:Seven articles were included in this systematic review. Articles eligible for inclusion(a) investigated cochlear implantation of any CI system in adults with post-lingual onset of deafness and normal cochlear anatomy; (b) investigated the relationship between angular insertion depth and speech perception; (c) measured angular insertion depth on imaging; and (d) measured speech perception at, or beyond 1-year post-activation.
DATA EXTRACTION AND SYNTHESIS:In included studies; quality was judged low-to-moderate and risk of bias, evaluated using a Quality-in-Prognostic-Studies-tool (QUIPS), was high. Included studies were too heterogeneous to perform meta-analyses, therefore, effect estimates of the individual studies are presented. Six out of seven included studies found no effect of angular insertion depth on speech perception.
CONCLUSION:All included studies are characterized by methodological flaws, and therefore, evidence-based conclusions regarding the influence of angular insertion depth cannot be drawn to date.