Round window insertion of precurved electrodes is traumatic

Area of Science:

• Otolaryngology
• Neurosurgery
• Biomedical Engineering

Background:

• Cochlear implantation requires precise electrode insertion to minimize inner ear damage.
• Understanding the impact of surgical approach and electrode design on endocochlear trauma is crucial for improving patient outcomes.

Purpose of the Study:

• To evaluate the incidence of endocochlear trauma associated with different cochleostomy locations and electrode array sizes in a cadaveric model.

Main Methods:

• A cadaveric temporal bone study was conducted using fourteen temporal bones.
• Electrode arrays were inserted via various cochleostomy sites (round window, anterior inferior, superior) and through traditional cochleostomies.
• Two electrode array types, a larger precontoured and a thinner precurved array, were used, with histological analysis performed by a blinded party.

Main Results:

• Seven of fourteen bones exhibited intracochlear trauma.
• Traditional cochleostomies showed no endocochlear trauma (0/4), while other insertion sites had varying trauma rates (up to 100% for superior cochleostomies).
• The thinner electrode array, though associated with less overall trauma (57% vs 42%), demonstrated a higher incidence of tip fold-over (2/7).

Conclusions:

• Traditional cochleostomy is the safest approach, minimizing endocochlear trauma during cochlear implant electrode insertion.
• Electrode array size had a minimal impact on trauma incidence, but thinner arrays posed a risk of distal trauma due to tip fold-over.