Insertion forces and intracochlear trauma in temporal bone specimens implanted with a straight atraumatic electrode...

Area of Science:

• Otorhinolaryngology
• Neurosurgery
• Biomedical Engineering

Background:

• Minimizing intracochlear trauma and preserving residual hearing are crucial during cochlear implantation.
• Understanding insertion forces is essential for developing safer cochlear implant electrode insertion techniques.

Purpose of the Study:

• To evaluate insertion forces during manual insertion of a straight atraumatic electrode in human temporal bones.
• To correlate insertion forces with post-implantation histologic findings of intracochlear trauma.

Main Methods:

• Ten fresh frozen human temporal bones underwent canal wall down mastoidectomy.
• A 16-mm straight atraumatic electrode was inserted using a one-axis force sensor to measure insertion forces.
• Histologic evaluation assessed intracochlear trauma, including electrode dislocation.

Main Results:

• Mean insertion force was 0.003 ± 0.005 N.
• Electrode dislocation into the scala vestibuli occurred in 4 out of 10 samples.
• Significantly higher insertion forces were measured at dislocation sites compared to non-traumatized cochleae (p < 0.04).

Conclusions:

• Insertion forces leading to basilar membrane trauma may be lower than previously reported.
• The study suggests that even atraumatic electrodes can cause trauma if insertion forces are not carefully managed.
• These findings emphasize the importance of precise force monitoring during cochlear implant electrode insertion to prevent intracochlear damage.