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Updated: Apr 3, 2026
Author Spotlight: Advancements in Impedance Monitoring for Cochlear Implant Surgery
Published on: August 4, 2023
Measurement of Cochlear Implant Electrode Position From Intraoperative Post-insertion Skull Radiographs: A Validation
Maja Svrakic1, David R Friedmann, Phillip M Berman
1*Department of Otolaryngology and Communicative Disorders, North Shore Long Island Jewish Medical Center †Department of Otolaryngology ‡Department of Radiology, New York University Langone Medical Center, New York, New York, U.S.A.
Objective:
To validate a method of measuring angular depth of insertion (aDOI) as well as positional depth of each electrode contact in a cochlear implant by using intraoperative postinsertion skull radiographs.
Study Design:
Retrospective review.
Setting:
Tertiary referral center.
Patients:
Intraoperative postinsertion radiographs obtained from 18 cochlear implant recipients were chosen for analysis. One high-resolution computer tomography scan of the head with the electrode in place was also analyzed. One cadaveric temporal bone with an inserted electrode provided additional data for analysis.
Intervention:
aDOI and position of each electrode contact were measured from the radiographs using readily available software. High-resolution computer tomography imaging of the cochlea and electrode were reconstructed in three dimensions and used to simulate head rotation during intraoperative radiographs. The cadaveric temporal bone was imaged by x-ray at various acquisition angles.
Main Outcome Measures:
We evaluated the error introduced in measuring aDOI by assessing intra- and inter-rater variability. We also evaluated the error introduced by x-ray acquisition at nonstandardized angles by analyzing the three-dimensional construct and the cadaveric temporal bone.
Results:
The concordance correlation coefficients for intrarater (0.991) and inter-rater (0.996) variability in aDOI measurement were excellent. The error introduced by nonstandardized x-ray acquisition angles was only -12.5 degrees to +15.8 degrees even at the limits of clinically relevant head rotation.
Conclusions:
The intraoperative postinsertion radiograph is sufficient for estimating positional depth of electrode contacts and the aDOI. This measure is robust in the face of nonstandardized x-ray acquisition angles, and shows good intra- and inter-rater variability.
