(861) Multimodal Applications of the Insertion Probe L in Cochlear Implantation

Introduction: Cochlear implantation (CI) in the setting of ossification, prior surgery, or intracochlear pathology presents unique technical challenges in electrode insertion. Depth gauges are commonly used for electrode length assessment, however, the Insertion Probe L (IPL) is a rigid probe with broader intraoperative utility in complex CI cases that have not been well characterized.

Methods: A retrospective case series was conducted at a tertiary academic center reviewing CI surgeries performed from 01/2025 to 01/2026 in which the IPL was utilized. The intervention consisted of intraoperative use of the IPL to assess cochlear patency, insertion trajectory, obstruction, and estimated insertion depth. Primary outcome measures included the intraoperative utility of the probe and its impact on surgical decision-making, including electrode selection. Independent variables included underlying pathology and surgical context prompting probe use.

Results: Eight CI cases employed the IPL in complex settings including cochlear ossification, intracochlear tumor, inflammatory inner ear disease, device failure requiring reimplantation, and prior otologic surgery with fibrosis or cholesteatoma. In ossified cochleae, the probe confirmed scala vestibuli patency and estimated achievable insertion depth, enabling full electrode insertion despite resistance. In revision and reimplantation cases, the probe facilitated creation or confirmation of a patent intracochlear track following device removal, fibrosis, or tip fold-over. In cases of suspected obstruction, the probe assisted in clearance of a cochlear lumen tract when electrode insertion was limited. Probe use informed intraoperative decisions regarding electrode selection and advancement. Full insertion, of the intended electrode, was achieved in all cases with satisfactory intraoperative testing and imaging. No probe-related complications were observed. Limited postoperative speech perception data demonstrated improvement.

Conclusions: The IPL is a versatile intraoperative instrument with multiple practical applications in complex CI surgery.