TABLE 1.
Characteristics of included studies
| Angular Insertion Depth Details | Outcome Measurements | Confounders | |||||||
| First Author Year | Number of Implants, Design, Surgical Approach | Electrodes Implanted | Mean (SD) | Range | Type of Test | Mean (SD) | Range | Collected | Included in Analysis |
| De Seta 2016 | 26 Prospective NRa | M1 | 643 (93) | 510–880 | Fournier word test In quiet @ 70 dB In noise @ SNR +5, SNR +10, SNR+15 | 64 (6) | NRa | Age at implantation, history of hearing loss, hearing aid use, cochlear diameter, cochlear height, electrode to modiolus distance @ 180 and 360 degrees | – |
| Hilly 2016 | 120 Retrospective C | AB1 | 382 (98) | 180–720 | HINT sentence test In quiet @ 60 dB | 76 (26) | NRa | Age at implantation, preoperative outcome score, preoperative residual hearing, number of intracochlear contacts | – |
| Holden 2013 | 114 Prospective C | AB1, AB2, AB3, C2, C3 | NRa | NRa | CNC word test In quiet @ 60 dB | 62 (21) | 3–89 | Age at implantation, educational level, cognitive measures, history of hearing loss, hearing aid use, lip-reading ability, preoperative outcome score, preoperative residual hearing, electrode type, scalar location, basal angular insertion depth, electrode to modiolus proximity | – |
| Marrinan 2004 | 28 Retrospective NRa | C2 | NRa | NRa | CNC word test In quiet @ 70 dB CUNY sentence test In quiet @ 70 dB In noise @ SNR +10 | NRa | NRa | Age at implantation, history of hearing loss, preoperative outcome score | – |
| O’Connell 2016 | 137 107 Retrospective RW 39% ERW 34% C 37% | M1, M2, M3, M4, C1, C3, AB1, AB4 | 420 (99) | 208–715 | CNC word test In quiet @ 60 dB AzBio sentence test In quiet @ 60 dB | 47 (23) 57 (28) | Age at implantation, category of electrode type, surgical approach, cochlear volume, Scalar location | Age at implantation, category of electrode type, surgical approach, cochlear volume, Scalar location | |
| Van der Beek 2005 | 15 Prospective C | AB2 | 439 (73) | 105–559 | CVC word test In quiet @ 65 and 75 dB | NRa | NRa | Age at implantation, Duration of deafness, Preoperative outcome score, Preoperative residual hearing, Electrode to modiolus proximity | - |
| Van der Marel 2015 | 162 Retrospective ERW | AB1, AB2 | 477 (70) | 303–678 | CVC word test In quiet average @ 65 + 75dB | Word score 54 (22) Phoneme score 74 (19) | 0–93 0–97 | Age at implantation, history of hearing loss, preoperative outcome score, electrode to modiolus proximity, linear insertion depth in millimeters | Duration of deafness Preoperative phoneme score Preoperative word score |
aNR, not reported in paper and missing information not able to retrieve after contact with author.