Sensitivity and Costs of Intraoperative Trans-Impedance Matrix Recordings, Spread of Excitation Functions, and X-ray Imaging in Detecting Cochlear Implant Tip Foldovers.

Objective: Evaluate the sensitivity and financial costs of Trans-Impedance Matrix recordings, Spread of Excitation functions, and x-rays in detecting cochlear implant tip foldovers.

Setting: Tertiary academic medical center.

Patients: 113 ears of 108 patients.

Interventions: Following cochlear implantation and before concluding surgery, intraoperative Trans-Impedance Matrix recordings, Spread of Excitation functions, and x-rays were conducted to evaluate presence of tip foldover.

Main outcome measures: Presence of tip foldover; recording time necessary for and costs of Trans-Impedance Matrix, spread of excitation, and x-rays.

Results: There were six tip foldovers. Trans-Impedance Matrix showed 100% sensitivity, 100% specificity, 100% positive predictive value, and 100% negative predicative value in detecting tip foldovers. Spread of excitation showed 29% sensitivity, 99% specificity, 67% positive predictive value, and 95% negative predicative value. Trans-Impedance Matrix recordings were completed significantly faster than spread of excitation and x-rays. Elimination of x-rays from our intraoperative workflow results in a twofold cost reduction.

Conclusion: Trans-Impedance Matrix recordings have potential great clinical utility in evaluating proper CI placement intraoperatively and reducing costs of surgery while not compromising patient care. Given the low tip foldover rate, a multicenter study is in progress to evaluate the sensitivity, specificity, positive predictive value, and negative predicative value of Trans-Impedance Matrix in a larger dataset. This can provide better guidance to cochlear implant clinics interested in evaluating the impact of using Trans-Impedance Matrix on patient care as well as the economics of reducing use of intraoperative imaging.