Assessment of Angular Insertion-Depth of Bilateral Cochlear Implants Using Plain X-ray Scans

Area of Science:

• Otolaryngology
• Medical Imaging
• Neurosurgery

Background:

• Cochlear implantation is a common treatment for severe hearing loss.
• Accurate measurement of electrode insertion depth is crucial for optimizing hearing outcomes.
• Plain x-ray scans offer a readily available imaging modality.

Purpose of the Study:

• To assess the feasibility and reliability of measuring angular depth of insertion (aDOI) using plain x-ray scans in pediatric cochlear implant patients.
• To evaluate the impact of head positioning on aDOI measurements.
• To determine the symmetry of aDOI between ears in bilateral simultaneous cochlear implantations.

Main Methods:

• Retrospective analysis of intraoperative anterior-posterior and oblique x-ray scans from 50 children (100 ears) who underwent bilateral simultaneous cochlear implantation.
• Three independent observers evaluated and compared aDOI measurements.
• Analysis included inter-rater agreement, effect of head position, and inter-aural symmetry.

Main Results:

• High inter-rater agreement (R=0.99) for aDOI measurements, with small differences (2-7 degrees) among observers.
• A 45-degree head rotation resulted in a median aDOI difference of 14 degrees, showing excellent correlation.
• High asymmetry in aDOI between ears was observed, with a median difference of 39 degrees.

Conclusions:

• Intraoperative plain x-ray assessment of angular depth of insertion is efficient and reliable.
• Head positioning has a minimal impact on measurement accuracy.
• Further research is needed to correlate aDOI and insertion symmetry with functional outcomes.