Intraoperative Correlates of Electrode Array Insertion Dynamics and Electrophysiological Parameters Under SmartNav-Guided Cochlear Implantation: An Exploratory Single-Centre Study

Background/Objectives: Real-time intraoperative navigation systems such as SmartNav (Cochlear Ltd., Sydney, Australia) provide objective feedback on electrode array insertion during cochlear implantation, yet it remains unclear whether the parameters they record vary across the device- and patient-level factors a surgeon selects between. This study compared intraoperative insertion dynamics and electrophysiological parameters across electrode array design (CI622 slim-straight versus CI632 slim-modiolar), surgical approach (round window versus cochleostomy), and patient age (children versus adults). Methods: Twenty-nine consecutive implantations in 26 patients (three children implanted bilaterally) performed with SmartNav monitoring were analysed. Insertion angle, insertion speed, total insertion time, the number of contacts (of 22) with in-range impedance, and the number of contacts (of 22) with a measurable neural response telemetry (NRT) response were extracted from device logs and operative records; insertion kinetics were available for 22 of 29 implantations. Distributions were non-normal, so comparisons used the Mann–Whitney U test with rank-biserial effect sizes, Fisher’s exact test, Kruskal–Wallis test, and Spearman correlation. Exploratory multivariable regression, Brown–Forsythe variance testing, bootstrap effect sizes, and outlier-inclusive and one-ear-per-patient sensitivity analyses were additionally applied; no correction for multiple comparisons was made. Results: The CI632 array was advanced faster per electrode than the CI622 (median 0.33 versus 0.56 s/electrode; n = 5 versus 16; p = 0.015; rank-biserial r = −0.75; bootstrap 95% CI −1.00 to −0.38), but the difference was not significant when one implausible outlying value was retained (p = 0.113). Impedance and NRT status were modestly correlated (ρ = 0.388, p = 0.037, uncorrected) and unchanged after adjustment for age band (partial ρ = 0.389), but were not significant in the one-ear-per-patient analysis. The study was unable to detect a difference between age groups or between surgical approaches (five cochleostomies versus 24 round window insertions) in any parameter, and impedance status varied minimally across all strata. Conclusions: Within the limits of a small, unbalanced cohort, SmartNav-derived parameters did not differ detectably across patient age or surgical approach. The data suggest that electrode array design is associated with per-electrode insertion pacing, an observation that depends on a single excluded data point and requires confirmation. The impedance–NRT association is exploratory, is consistent with a chance finding once multiplicity is considered, and should not yet be regarded as an intraoperative integrity signal. No clinical outcome was linked to the intraoperative parameters, so no inference about the clinical superiority of either array or approach can be drawn.