Percutaneous cochlear access using bone-mounted, customized drill guides: demonstration of concept in vitro

Area of Science:

• Neurosurgery
• Otolaryngology
• Medical Device Engineering

Background:

• Percutaneous cochlear access is crucial for cochlear implantation.
• Previous methods utilized image guidance with fiducial markers.
• A simpler, more reliable method involves using custom drill guides for predetermined trajectories.

Purpose of the Study:

• To evaluate the efficacy of custom-made, bone-mounted drill guides for percutaneous cochlear access.
• To assess the accuracy and safety of this technique in cadaveric specimens.

Main Methods:

• Eight cadaveric temporal bones were used.
• Custom drill guides were manufactured based on computed tomography (CT) scans, planning a trajectory to the cochlea.
• The drill guide was mounted, and a 1-mm drill bit was passed through the guide.
• The trajectory's accuracy and proximity to critical facial recess structures were measured.

Main Results:

• Accurate percutaneous cochlear access was achieved in 7 out of 8 specimens.
• The drill trajectory successfully reached the cochlea without damaging critical structures in most cases.
• The average shortest distance to the chorda tympani, incus buttress, and facial nerve was recorded, indicating a safe margin.

Conclusions:

• Customized drill guides, based on preintervention radiographic studies, are effective for achieving percutaneous cochlear access.
• This technique offers a simplified and potentially more accurate approach for cochlear access in surgical procedures.