Related Experiment Video
Updated: Aug 8, 2026
Testing a Cochlear Implant Electrode Insertion Training System for Optimal Electrode Array Placement in Different Inner Ear Anatomies
Published on: February 6, 2026
Scalar position characteristics and translocation rates of different lateral wall electrodes within the cochlear
Irumee Pai1,2, Paolo Rondi3, Isobel Morley4
1St. Thomas' Hearing Implant Centre, Guy's and St. Thomas' NHS Foundation Trust, 2nd Floor Lambeth Wing, London, UK. irumee.i.pai@kcl.ac.uk.
Purpose:
This retrospective study systematically compared scalar position characteristics and translocation (STL) rates within the cochlear basal turn (CBT) across three different lateral wall (LW) electrodes.
Methods:
The study included 148 morphologically normal cochleae implanted with Advanced Bionics SlimJ (ABSJ, n = 51), Cochlear Slim Straight (CSS, n = 51), or MED-EL FLEX (MFX, n = 46). Cochlear dimensions (distances A and B) and angular insertion depth (AID) were measured by two observers. Scalar position was assessed on postoperative cone-beam CT at 90°, 180°, 270°, and 360° by three observers using a five-point scale (1-2 = scala vestibuli (SV), 3 = central, 4-5 = scala tympani (ST)).
Results:
Distances A and B were comparable across groups (p > .05). Mean AID was significantly greater for MFX (p < .001). MFX had higher median scalar scores than CSS at every angle (all Bonferroni-adjusted p < .001) and than ABSJ at 180°, 270°, and 360° (adjusted p < .001). ST retention (all four median scores ≥ 3) was observed in 92.2% of ABSJ, 78.4% of CSS, and 100% of MFX cases, while STL (median score decreased to 1-2 and remained ≤ 3) occurred in 7.8%, 15.7%, and 0%, respectively. MFX demonstrated significantly lower STL and higher ST retention rates than CSS (adjusted p = .018 and p < .003, respectively). No independent associations of distance A, distance B, or AID with either STL or ST retention were identified (all p ≥ .54).
Conclusion:
Significant differences in scalar position and STL rates were observed among LW electrodes, with MFX showing the most stable ST placement.
