Modiolar coiling, electrical thresholds, and speech perception after cochlear implantation using the Nucleus Contour Advance electrode with the advance off stylet technique

Objective: Perimodiolar electrode arrays were developed in an attempt to improve stimulation of specific neural populations and to decrease electrical thresholds, thereby decreasing power consumption. Postoperative radiographs show that coiling of the arrays is variable. Our previous study explored the relationship between the angle of coiling, threshold levels, and functional outcomes using the Nucleus Contour electrode array. This study compares coiling angle, electrical threshold levels, and speech perception measures with the Nucleus Contour Advance electrode array implanted using the new advance off stylet technique versus the Nucleus Contour electrode array implanted using the standard technique. Study Design: Retrospective review. Setting: University medical center. Patients: Forty-two adults and children with normal cochlear anatomy implanted with the Nucleus CI24RCA electrode using the advance off stylet technique with at least 1-year follow-up. Intervention: Therapeutic. Main Outcome Measures: Computer-aided radiographic analysis of perimodiolar electrode placement, electrical threshold measurements, and speech perception outcome measures at 1 year postimplantation. Results: The degree of modiolar coiling was tighter using the new electrode and technique in comparison with standard insertion technique using the Nucleus Contour electrode array. The tighter coiling tended to result in higher electrical thresholds. Lower speech perception outcome measures tended to correlate with a higher degree of coiling. Conclusion: The Nucleus Contour Advance electrode array combined with the advance off stylet technique resulted in a more consistent perimodiolar position. However, the tighter coiling resulted in statistically significant increased electrical thresholds and decreased speech perception outcomes. This finding may be secondary to multiple factors, not just coiling angle.